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Patel S, Rizvi SSA, Choi JH, Horan DP, Weber MP, Maynes EJ, Luc JGY, Aburjania N, Entwistle JW, Morris RJ, Massey HT, Tchantchaleishvili V. Management and outcomes of left ventricular assist device-associated endocarditis: a systematic review. Ann Cardiothorac Surg 2019; 8:600-609. [PMID: 31832350 DOI: 10.21037/acs.2019.04.04] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Left ventricular assist device (LVAD)-associated endocarditis remains poorly studied, especially in newer continuous-flow LVADs (CF-LVADs). The aim of this review was to assess outcomes of patients with LVAD-associated endocarditis, as stratified by CF-LVAD and pulsatile LVAD (P-LVAD) use as well as by different interventions and pathogen types. Methods An electronic search was performed to identify studies in the English literature on LVAD-associated endocarditis. Results Overall, 16 articles with 26 patients were included; seven had CF-LVADs and 19 had P-LVADs; time to development of endocarditis was 91 days (152 vs. 65 days, respectively, P=0.05). Eleven of 25 patients were treated with antibiotics only. Remaining 14 patients received antibiotics, however, they also underwent additional surgical intervention. One patient was treated with embolization alone for mycotic aneurysm and was therefore excluded. At a median follow-up time of 344 days post implant, there was no difference in overall mortality between CF-LVAD and P-LVAD-associated endocarditis patients (57.9% vs. 42.9%, P=0.81). Patients who underwent additional surgical intervention had higher overall survival compared to those treated with antibiotics alone (71.4% vs. 27.3%, P=0.07); with no difference in outcomes amongst those who underwent surgical device exchange as compared to heart transplantation (80.0% vs. 66.7%; P=0.23). Conclusions Compared to patients with P-LVADs, CF-LVAD patients appeared to be resistant to early development of LVAD-associated endocarditis. There was a trend towards high survival observed amongst patients who underwent additional surgical intervention as compared to those treated with antibiotics alone, with no difference amongst surgical device exchange as compared to heart transplantation. Advantages of additional surgical intervention vs. medical therapy alone deserves further exploration to determine its applicability in CF-LVADs.
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Affiliation(s)
- Sinal Patel
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Syed Saif Abbas Rizvi
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Jae Hwan Choi
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Dylan P Horan
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Matthew P Weber
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Elizabeth J Maynes
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Jessica G Y Luc
- Division of Cardiovascular Surgery, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nana Aburjania
- Division of Infectious Diseases, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - John W Entwistle
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Rohinton J Morris
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Howard T Massey
- Division of Cardiac Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Konstantinou K, Keeble TR, Kelly PA, Alsanjari O, Napp LC, Karamasis GV, Davies JR. Protected percutaneous coronary intervention with Impella CP in a patient with left main disease, severe left ventricular systolic dysfunction and established hemolysis. Cardiovasc Diagn Ther 2019; 9:194-199. [PMID: 31143642 DOI: 10.21037/cdt.2019.02.06] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The use of the Impella device in patients with left ventricular (LV) systolic impairment undergoing left main (LM) percutaneous coronary intervention (PCI) has been growing exponentially. Data from observational studies and registries demonstrate that Impella-assisted high-risk PCI is safe and effective with a low rate of peri-procedural complications. Hemolysis is a potential limitation of virtually all mechanical circulatory support devices and a small incidence of hemolysis has been associated with Impella use. The safety and feasibility of Impella use in patients with established hemolysis has not been previously evaluated. We report the first described case in the literature of Impella-assisted left main stem (LMS) PCI in a patient with severe LV systolic dysfunction and autoimmune hemolytic anemia (AIHA). Despite the patient's high bleeding risk (active hemolysis, thrombocytopenia, impaired renal function, use of steroids), Impella placement and PCI were successfully performed without complication. Haemoglobin, bilirubin and lactate dehydrogenase (LDH) levels were closely monitored peri-procedurally with no evidence of exacerbation of the patient's hemolysis. We briefly discuss the mechanism of Impella-induced hemolysis and factors that can exacerbate hemolysis.
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Affiliation(s)
- Klio Konstantinou
- Department of Cardiology, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals, Basildon, UK.,Anglia Ruskin University School of Medicine, Faculty of Medical Science, Chelmsford, UK
| | - Thomas R Keeble
- Department of Cardiology, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals, Basildon, UK.,Anglia Ruskin University School of Medicine, Faculty of Medical Science, Chelmsford, UK
| | - Paul A Kelly
- Department of Cardiology, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals, Basildon, UK
| | - Osama Alsanjari
- Department of Cardiology, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals, Basildon, UK.,Anglia Ruskin University School of Medicine, Faculty of Medical Science, Chelmsford, UK
| | - L Christian Napp
- Cardiac Arrest Centre, Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany
| | - Grigoris V Karamasis
- Department of Cardiology, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals, Basildon, UK.,Anglia Ruskin University School of Medicine, Faculty of Medical Science, Chelmsford, UK
| | - John R Davies
- Department of Cardiology, Essex Cardiothoracic Centre, Basildon and Thurrock University Hospitals, Basildon, UK.,Anglia Ruskin University School of Medicine, Faculty of Medical Science, Chelmsford, UK
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Zhang Y, Hu S, Zhou JY, Sun HS, Zhang H, Zheng Z, Zhu XD, Li GR, Gui XM, Zhan Z, Jin DH. Design and performance testing of an axial-flow ventricular assist device developed at the Fu Wai Hospital in Beijing. Int J Artif Organs 2018; 31:983-7. [PMID: 19089800 DOI: 10.1177/039139880803101108] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Purpose Various ventricular assist devices (VADs) have been developed for clinical use in recent years. The aim of a multidisciplinary research team at the Fuwai Hospital of the Peking Union Medical College is to design and develop an axial flow left ventricular assist device (LVAD) for adults. Methods Using Computational Fluid Dynamics (CFD), the inflow characteristics of the axial flow pump were analyzed. After CFD analysis, the axial pump was fabricated using a 5-axis, computer numerical control (CNC) milling machine. Performances of the pump both in vitro and in vivo were tested. Results This VAD, which was developed after numerous CFD analyses for the flow characteristics of the pump, is 58.5 mm long, 30 mm wide and weighs 120 g. The pump can deliver 5 lpm for pressures of 100 mmHg over 8500 rpm. The NIH value was 0.01 g/100 L. The hemolysis, which was evaluated in an in vivo test, was a bit higher than the normal value, but remained within an acceptable range. Conclusions Performance of the pump in vitro and in vivo was considered sufficient for an LVAD. Further design improvements are being undertaken in terms of hemolysis and thrombosis to improve the biocompatibility of the pump.
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Affiliation(s)
- Y. Zhang
- Research Center for Cardiovascular Regenerative Medicine, Fu Wai Hospital, Beijing - China
- Department of Cardiovascular Surgery, Fu Wai Hospital, Beijing - China
| | - S.S. Hu
- Research Center for Cardiovascular Regenerative Medicine, Fu Wai Hospital, Beijing - China
- Department of Cardiovascular Surgery, Fu Wai Hospital, Beijing - China
| | - J.-Y. Zhou
- Research Center for Cardiovascular Regenerative Medicine, Fu Wai Hospital, Beijing - China
| | - H.-S. Sun
- Department of Cardiovascular Surgery, Fu Wai Hospital, Beijing - China
| | - H. Zhang
- Research Center for Cardiovascular Regenerative Medicine, Fu Wai Hospital, Beijing - China
- Department of Cardiovascular Surgery, Fu Wai Hospital, Beijing - China
| | - Z. Zheng
- Research Center for Cardiovascular Regenerative Medicine, Fu Wai Hospital, Beijing - China
- Department of Cardiovascular Surgery, Fu Wai Hospital, Beijing - China
| | - X.-D. Zhu
- Department of Cardiovascular Surgery, Fu Wai Hospital, Beijing - China
| | - G.-R. Li
- Research Center for Cardiovascular Regenerative Medicine, Fu Wai Hospital, Beijing - China
- Department of Cardiovascular Surgery, Fu Wai Hospital, Beijing - China
| | - X.-M. Gui
- School of Jet Propulsion, Beijing University of Aeronautics and Astronautics, Beijing - China
| | - Z. Zhan
- School of Jet Propulsion, Beijing University of Aeronautics and Astronautics, Beijing - China
| | - D.-H. Jin
- School of Jet Propulsion, Beijing University of Aeronautics and Astronautics, Beijing - China
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Gurvits GE, Fradkov E. Bleeding with the artificial heart: Gastrointestinal hemorrhage in CF-LVAD patients. World J Gastroenterol 2017; 23:3945-3953. [PMID: 28652649 PMCID: PMC5473115 DOI: 10.3748/wjg.v23.i22.3945] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 04/10/2017] [Accepted: 05/09/2017] [Indexed: 02/06/2023] Open
Abstract
Continuous-flow left ventricular assist devices (CF-LVADs) have significantly improved outcomes for patients with end-stage heart failure when used as a bridge to cardiac transplantation or, more recently, as destination therapy. However, its implantations carries a risk of complications including infection, device malfunction, arrhythmias, right ventricular failure, thromboembolic disease, postoperative and nonsurgical bleeding. A significant number of left ventricular assist devices (LVAD) recipients may experience recurrent gastrointestinal hemorrhage, mainly due to combination of antiplatelet and vitamin K antagonist therapy, activation of fibrinolytic pathway, acquired von Willebrand factor deficiency, and tendency to develop small intestinal angiodysplasias due to increased rotary speed of the pump. Gastrointestinal bleeding in LVAD patients remains a source of increased morbidity including the need for blood transfusions, extended hospital stays, multiple readmissions, and overall mortality. Management of gastrointestinal bleeding in LVAD patients involves multidisciplinary approach in stabilizing the patients, addressing risk factors and performing structured endoluminal evaluation with focus on upper gastrointestinal tract including jejunum to find and eradicate culprit lesion. Medical and procedural intervention is largely successful and universal bleeding cessation occurs in transplanted patients.
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Computational Analysis of Pumping Efficacy of a Left Ventricular Assist Device according to Cannulation Site in Heart Failure with Valvular Regurgitation. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:6930482. [PMID: 28115981 PMCID: PMC5221291 DOI: 10.1155/2016/6930482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 11/04/2016] [Accepted: 12/05/2016] [Indexed: 11/18/2022]
Abstract
Mitral valve regurgitation (MR) causes blood to flow in two directions during contraction of the left ventricle (LV), that is, forward into the aorta and backward into the left atrium (LA). In aortic valve regurgitation (AR), leakage occurs from the aorta into the LV during diastole. Our objective is to analyze the contribution of a left ventricular assist device (LVAD) to MR and AR for the following two different cannulation sites: from the LA to the aorta (LAAO) and from the LV to the aorta (LVAO). Using a computational method, we simulated three ventricular conditions (normal [HF without valvular regurgitation], 5% MR, and 5% AR) in three groups (control [no LVAD], LAAO, and LVAO). The results showed that LVAD with LAAO cannulation is appropriate for recovery of the MR heart, and the LVAD with LVAO cannulation is appropriate for treating the AR heart.
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Abstract
Ventricular assist devices (VADs) have revolutionized longterm care for patients with congestive heart failure. These patients represent about 1% of the adults in the United States, considering that heart failure is a contributing factor in more than 250,000 deaths annually. It has been estimated that about 60,000 patients per year in the United States could benefit from heart transplantation or long-term mechanical support. Because of the short supply of donor hearts for transplant, assist devices have become of great value. At least four assist devices are clinically available, and two other devices are being investigated. Because cardiopulmonary bypass is required for implantation of these devices, anesthetizing these critically compromised patients requires extensive monitoring, skillful anesthetic management, and expert postoperative care.
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Affiliation(s)
- Ibrahim El-Magharbel
- Department of Anesthesiology, Santa Monica UCLA Medical Center, Los Angeles, CA 90095-1778, USA
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7
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Abstract
Controller algorithms are an important feature for assessment of ventricular assist device performance. Flow estimation is one algorithm implemented in the HeartWare continuous-flow ventricular assist device pump system. This parameter estimates flow passing through the pump and is calculated using speed, current, and hematocrit. In vitro and in vivo studies were conducted to assess the algorithm accuracy. During in vitro testing, three pumps were tested in four water-glycerol solutions at 37°C with viscosities equivalent to hematocrits of 20, 30, 40, and 50%. By using a linear regression model, a correlation coefficient of >0.94 was observed between measured and estimated flow for all conditions. In vivo studies (n = 9) were conducted in an ovine model where a reference flow probe was placed on the outflow graft and speed was adjusted from 1,800 to 4,000 revolutions per minute. During in vivo experiments, estimated pump flow (mean, minimum, and maximum) was compared with measured pump flow. The best-fit linear regression equation for the data is y = 0.96x + 0.54, r = 0.92. In addition, waveform fidelity was high (r > 0.96) in normal (i.e., nonsuction) cases where flow pulsatility was >2 L/min. The flow estimation algorithm demonstrated strong agreement with measured flow, both when analyzing average waveform magnitude and fidelity.
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Ibrahim M, Kilic A, Atluri P. Left Ventricular Assist Devices and Small Body Surface Area – A Clinical Concern? –. Circ J 2016; 80:1901-2. [DOI: 10.1253/circj.cj-16-0749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michael Ibrahim
- Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania
| | - Arman Kilic
- Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania
| | - Pavan Atluri
- Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania
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Grimm JC, Magruder JT, Kemp CD, Shah AS. Late Complications Following Continuous-Flow Left Ventricular Assist Device Implantation. Front Surg 2015; 2:42. [PMID: 26347873 PMCID: PMC4541033 DOI: 10.3389/fsurg.2015.00042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 08/03/2015] [Indexed: 12/20/2022] Open
Abstract
Left ventricular assist devices have become standard therapy for patients with end-stage heart failure. They represent potential long-term solutions for a growing public health problem. However, initial enthusiasm for this technology has been tempered by challenges posed by long-term support. This review examines these challenges and out current understanding of their etiologies.
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Affiliation(s)
- Joshua C Grimm
- Division of Cardiac Surgery, The Johns Hopkins Hospital , Baltimore, MD , USA
| | - J Trent Magruder
- Division of Cardiac Surgery, The Johns Hopkins Hospital , Baltimore, MD , USA
| | - Clinton D Kemp
- Division of Cardiac Surgery, The Johns Hopkins Hospital , Baltimore, MD , USA
| | - Ashish S Shah
- Division of Cardiac Surgery, The Johns Hopkins Hospital , Baltimore, MD , USA
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10
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Characteristics of gastrointestinal bleeding after placement of continuous-flow left ventricular assist device: a case series. Dig Dis Sci 2015; 60:1859-67. [PMID: 25616611 DOI: 10.1007/s10620-015-3538-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 01/12/2015] [Indexed: 12/14/2022]
Abstract
BACKGROUND Medical management of patients with continuous-flow left ventricular assist devices (LVADs) remains challenging for the gastroenterologist given their high risk of gastrointestinal bleeding (GIB) and need for continuous anticoagulation. AIMS Our aim was to better characterize LVAD patients who presented with a GIB at our facility and delineate the prevalence, presentation, time to diagnosis, management, and therapeutic endoscopic interventions, including small bowel tools that may offer additional benefit. METHODS We retrospectively reviewed adult patients (>18 years) who underwent LVAD implantation at our tertiary care facility between October 2011 and October 2013. Electronic medical records were reviewed for presenting symptoms, average days to initial and repeat GIB, hospital course, and techniques that led to diagnosis and hemostasis. RESULTS Eighteen patients underwent LVAD implantation, of which 61 % presented with a GIB for a total of 20 presentations (1.8 per patient). Mean time to initial GIB was 154 days. Patients required an average of 1.8 endoscopic procedures per admission. Esophagogastroduodenoscopy (EGD) and push enteroscopy (PE) were more likely to lead to a diagnosis, and EGD was the most commonly used diagnostic tool at initial presentation. Sixty percent of patients who initially received EGD presented with a recurrent GIB and required PE, which was diagnostic and therapeutic for small bowel angiodysplasias in 80 % of cases. CONCLUSION We found a higher GIB rate compared with prior studies. Bleeding events were associated with multiple procedures and interventions. We recommend an algorithmic approach to LVAD patients who bleed. Our experience suggests that PE is warranted at initial presentation in order to achieve hemostasis, prevent recurrent GIB, and decrease subsequent readmission rates.
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11
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Sheriff J, Girdhar G, Chiu WC, Jesty J, Slepian MJ, Bluestein D. Comparative efficacy of in vitro and in vivo metabolized aspirin in the DeBakey ventricular assist device. J Thromb Thrombolysis 2015; 37:499-506. [PMID: 24043375 DOI: 10.1007/s11239-013-0997-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Ventricular assist devices (VADs) are implanted in patients with end-stage heart failure to provide both short- and long-term hemodynamic support. Unfortunately, bleeding and thromboembolic complications due to the severely disturbed, dynamic flow conditions generated within these devices require complex, long-term antiplatelet and anticoagulant therapy. While several studies have examined the effectiveness of one such agent, aspirin, under flow conditions, data comparing the efficacy of in vitro and in vivo metabolized aspirin is lacking. Two sets of studies were conducted in vitro with purified human platelets circulating for 30 min in a flow loop containing the DeBakey VAD (MicroMed Cardiovascular, Houston, TX, USA): (a) 20 μM aspirin was added exogenously in vitro to platelets isolated from aspirin-free subjects, and (b) platelets were obtained from donors 2 h (n = 14) and 20 h (n = 13) after ingestion of 1,000 mg aspirin. Near real-time platelet activation state (PAS) was measured with a modified prothrombinase-based assay. Platelets exposed to aspirin in vitro and in vivo (metabolized) showed 28.2 and 25.3 % reduction in platelet activation rate, respectively, compared to untreated controls. Our results demonstrate that in vitro treatment with antiplatelet drugs such as aspirin is as effective as in vivo metabolized aspirin in testing the effect of reducing shear-induced platelet activation in the VAD. Using the PAS assay provides a practical in vitro alternative to in vivo testing of antiplatelet efficacy, as well as for testing the thrombogenic performance of devices during their research and development.
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Affiliation(s)
- Jawaad Sheriff
- Department of Biomedical Engineering, Stony Brook University, T15-090 Health Sciences Center, Stony Brook, NY, 11794-8151, USA
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Woolley JR, Kormos RL, Teuteberg JJ, Bermudez CA, Bhama JK, Lockard KL, Kunz NM, Wagner WR. Preoperative liver dysfunction influences blood product administration and alterations in circulating haemostatic markers following ventricular assist device implantation. Eur J Cardiothorac Surg 2014; 47:497-504. [PMID: 24810756 DOI: 10.1093/ejcts/ezu183] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVES Preoperative liver dysfunction may influence haemostasis following ventricular assist device (VAD) implantation. The Model for End-stage Liver Disease (MELD) score was assessed as a predictor of bleeding and levels of haemostatic markers in patients with currently utilized VADs. METHODS Sixty-three patients (31 HeartMate II, 15 HeartWare, 17 Thoratec paracorporeal ventricular assist device) implanted 2001-11 were analysed for preoperative liver dysfunction (MELD) and blood product administration. Of these patients, 21 had additional blood drawn to measure haemostatic marker levels. Cohorts were defined based on high (≥18.0, n = 7) and low (<18.0, n = 14) preoperative MELD scores. RESULTS MELD score was positively correlated with postoperative administration of red blood cell (RBC), platelet, plasma and total blood product units (TBPU) , as well as chest tube drainage and cardiopulmonary bypass time. Age and MELD were preoperative predictors of TBPU by multivariate analysis. The high-MELD cohort had higher administration of TBPU, RBC and platelet units and chest tube drainage postimplant. Similarly, patients who experienced at least one bleeding adverse event were more likely to have had a high preoperative MELD. The high-MELD group exhibited different temporal trends in F1 + 2 levels and platelet counts to postoperative day (POD) 55. D-dimer levels in high-MELD patients became elevated versus those for low-MELD patients on POD 55. CONCLUSIONS Preoperative MELD score predicts postoperative bleeding in contemporary VADs. Preoperative liver dysfunction may also alter postoperative subclinical haemostasis through different temporal trends of thrombin generation and platelet counts, as well as protracted fibrinolysis.
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Affiliation(s)
- Joshua R Woolley
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA The Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Robert L Kormos
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA The Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA Department of Cardiovascular Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jeffrey J Teuteberg
- The Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Christian A Bermudez
- The Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA Department of Cardiovascular Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jay K Bhama
- The Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA Department of Cardiovascular Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kathleen L Lockard
- The Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Nicole M Kunz
- The Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - William R Wagner
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA Department of Cardiovascular Surgery, University of Pittsburgh, Pittsburgh, PA, USA
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Bansal S, Sai-Sudhakar CB, Whitson BA. Outcomes of continuous flow ventricular assist devices. World J Surg Proced 2014; 4:1-8. [DOI: 10.5412/wjsp.v4.i1.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/19/2013] [Accepted: 02/18/2014] [Indexed: 02/06/2023] Open
Abstract
Heart transplantation is commonplace, the supply is limited. Many exciting changes in the field of mechanical circulatory support have occurred in the past few years, including the axial flow pump. Left ventricular assist device (LVAD) therapy is ever evolving. As the use of LVAD therapy increases it is important to understand the indications, surgical considerations and outcomes.
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Abstract
Today's healthcare delivery system is challenged with an escalating number of heart failure patients who have exhausted medical therapy and overwhelmed the limits of organ transplantation. Scientific and technological advances over the last 20 years have now brought new surgical options to this vast patient population, ranging from ventricular restoration surgery to surgical gene therapy and beyond. This article reviews the myriad of surgical options that are available to these patients, their benefits and shortcomings, as well as potential future directions.
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DeBakey ME, Teitel ER. Use of the MicroMed®DeBakey VAD®for the treatment of end-stage heart failure. Expert Rev Med Devices 2014; 2:137-40. [PMID: 16293049 DOI: 10.1586/17434440.2.2.137] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Congestive heart failure poses a serious health risk to millions of Americans. Medical therapy for advanced stages of this condition has offered a minimal benefit and surgical treatment through transplantation is limited by the donor organ shortage. Although left ventricular assist devices may represent the future of therapy for this disease, the first generation of these pumps are limited by a number of factors that restrict their use to only the sickest of patients. The development and clinical use of the MicroMed DeBakey VAD represents a paradigm shift in the field of heart disease, supporting the notion that mechanical assistance can be achieved with continuous flow pumps. Axial flow devices, such as the DeBakey VAD, may open new doors for smaller patients and children, as well as improve the current standard of care for adults who require long-term circulatory support.
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Affiliation(s)
- Michael E DeBakey
- DeBakey Heart Center, Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
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16
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Rodriguez LE, Suarez EE, Loebe M, Bruckner BA. Ventricular assist devices (VAD) therapy: new technology, new hope? Methodist Debakey Cardiovasc J 2013; 9:32-7. [PMID: 23519193 DOI: 10.14797/mdcj-9-1-32] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ventricular assist devices are commonly utilized in the treatment of end-stage heart failure. Advances in continuous flow technology have improved efficiency, size, implantability, extended support, and overall patient outcomes. This has led to an expanded role of left ventricular assist device (LVAD) clinical use and applications. This review describes the advances and current state of LVAD devices and provides a future outlook for this technology.
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Affiliation(s)
- Limael E Rodriguez
- Methodist DeBakey Heart & Vascular Center, The Methodist Hospital, Houston, Texas, USA
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17
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Abstract
Systolic heart failure is a problem of substantial magnitude worldwide. Over the last 25 years great progress has been made in the medical management of heart failure with the recognition of the benefits of beta-adrenergic blockade, modulation of the renin-angiotensin and mineralocorticoid axes and judicious diuretic therapy. In addition, cardiac resynchronization therapy and prophylactic implantation of cardiac defibrillators have been responsible for measurable benefits in terms of functional status and dysrhythmia-related mortality, respectively. Unfortunately, progressive cardiac dysfunction often results in activity limitation, symptoms at rest, hospital admission, end-organ dysfunction and death despite maximal implementation of standard therapies. Heart transplantation has been a dramatic and effective therapy for end-stage heart failure, but it remains limited by a shortage of donor organs, strict criteria defining acceptable recipients and often unsatisfactory long-term success. Mechanical alternatives to support the failing circulation have been sought for the last 50 years. The history of device development has been marked in general by the slow progress achieved by a few dedicated and persevering pioneers. In the past decade, however, evolving technology has dramatically changed the field and broadened the options for the treatment of advanced heart failure. This review will detail the important milestones and the current state of the art, with an emphasis on implantable devices for intermediate to long term support.
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18
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A novel mathematical model of activation and sensitization of platelets subjected to dynamic stress histories. Biomech Model Mechanobiol 2013; 12:1127-41. [PMID: 23359062 DOI: 10.1007/s10237-013-0469-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 01/07/2013] [Indexed: 02/07/2023]
Abstract
Blood recirculating devices, such as ventricular assist devices and prosthetic heart valves, are burdened by thromboembolic complications requiring complex and lifelong anticoagulant therapy with its inherent hemorrhagic risks. Pathologic flow patterns occurring in such devices chronically activate platelets, and the optimization of their thrombogenic performance requires the development of flow-induced platelet activation models. However, existing models are based on empirical correlations using the well-established power law paradigm of constant levels of shear stress during certain exposure times as factors for mechanical platelet activation. These models are limited by their range of application and do not account for other relevant phenomena, such as loading rate dependence and platelet sensitization to high stress conditions, which characterize the dynamic flow conditions in devices. These limitations were addressed by developing a new class of phenomenological stress-induced platelet activation models that specifies the rate of platelet activation as a function of the entire stress history and results in a differential equation that can be directly integrated to calculate the cumulative levels of activation. The proposed model reverts to the power law under constant shear stress conditions and is able to describe experimental results in response to a diverse range of highly dynamic stress conditions found in blood recirculating devices. The model was tested in vitro under emulated device flow conditions and correlates well with experimental results. This new model provides a reliable and robust mathematical tool that can be incorporated into computational fluid dynamic studies in order to optimize design, with the goal of improving the thrombogenic performance of blood recirculating devices.
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Peura JL, Colvin-Adams M, Francis GS, Grady KL, Hoffman TM, Jessup M, John R, Kiernan MS, Mitchell JE, O'Connell JB, Pagani FD, Petty M, Ravichandran P, Rogers JG, Semigran MJ, Toole JM. Recommendations for the use of mechanical circulatory support: device strategies and patient selection: a scientific statement from the American Heart Association. Circulation 2012; 126:2648-67. [PMID: 23109468 DOI: 10.1161/cir.0b013e3182769a54] [Citation(s) in RCA: 260] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Third-generation continuous flow left ventricular assist devices. INNOVATIONS-TECHNOLOGY AND TECHNIQUES IN CARDIOTHORACIC AND VASCULAR SURGERY 2012; 5:250-8. [PMID: 22437454 DOI: 10.1097/imi.0b013e3181ee77a1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tremendous advances have been made in the treatment of end-stage heart failure patients with left ventricular assist devices (LVADs). An important factor playing a role in the improved clinical outcomes is the development of continuous flow, rotary LVADs. New technology using magnetic levitation and hydrodynamic suspension to eliminate contact bearings offers the potential of more durable and efficacious mechanical circulatory blood pumps. Clinical trials evaluating these novel "third-generation" LVADs are in progress.
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Milla F, Pinney SP, Anyanwu AC. Indications for Heart Transplantation in Current Era of Left Ventricular Assist Devices. ACTA ACUST UNITED AC 2012; 79:305-16. [DOI: 10.1002/msj.21313] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Role of echocardiography in the perioperative management of mechanical circulatory assistance. Best Pract Res Clin Anaesthesiol 2012; 26:199-216. [DOI: 10.1016/j.bpa.2012.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2012] [Accepted: 02/01/2012] [Indexed: 11/23/2022]
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Girdhar G, Xenos M, Alemu Y, Chiu WC, Lynch BE, Jesty J, Einav S, Slepian MJ, Bluestein D. Device thrombogenicity emulation: a novel method for optimizing mechanical circulatory support device thromboresistance. PLoS One 2012; 7:e32463. [PMID: 22396768 PMCID: PMC3292570 DOI: 10.1371/journal.pone.0032463] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 01/27/2012] [Indexed: 12/22/2022] Open
Abstract
Mechanical circulatory support (MCS) devices provide both short and long term hemodynamic support for advanced heart failure patients. Unfortunately these devices remain plagued by thromboembolic complications associated with chronic platelet activation--mandating complex, lifelong anticoagulation therapy. To address the unmet need for enhancing the thromboresistance of these devices to extend their long term use, we developed a universal predictive methodology entitled Device Thrombogenicity Emulation (DTE) that facilitates optimizing the thrombogenic performance of any MCS device--ideally to a level that may obviate the need for mandatory anticoagulation. DTE combines in silico numerical simulations with in vitro measurements by correlating device hemodynamics with platelet activity coagulation markers--before and after iterative design modifications aimed at achieving optimized thrombogenic performance. DTE proof-of-concept is demonstrated by comparing two rotary Left Ventricular Assist Devices (LVADs) (DeBakey vs HeartAssist 5, Micromed Houston, TX), the latter a version of the former following optimization of geometrical features implicated in device thrombogenicity. Cumulative stresses that may drive platelets beyond their activation threshold were calculated along multiple flow trajectories and collapsed into probability density functions (PDFs) representing the device 'thrombogenic footprint', indicating significantly reduced thrombogenicity for the optimized design. Platelet activity measurements performed in the actual pump prototypes operating under clinical conditions in circulation flow loops--before and after the optimization with the DTE methodology, show an order of magnitude lower platelet activity rate for the optimized device. The robust capability of this predictive technology--demonstrated here for attaining safe and cost-effective pre-clinical MCS thrombo-optimization--indicates its potential for reducing device thrombogenicity to a level that may significantly limit the extent of concomitant antithrombotic pharmacotherapy needed for safe clinical device use.
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Affiliation(s)
- Gaurav Girdhar
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Michalis Xenos
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Yared Alemu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Wei-Che Chiu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Bryan E. Lynch
- MicroMed Cardiovascular Inc., Houston, Texas, United States of America
| | - Jolyon Jesty
- Department of Hematology, Stony Brook University, Stony Brook, New York, United States of America
| | - Shmuel Einav
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
| | - Marvin J. Slepian
- Sarver Heart Center, University of Arizona, Tucson, Arizona, United States of America
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America
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Ensor CR, Paciullo CA, Cahoon WD, Nolan PE. Pharmacotherapy for Mechanical Circulatory Support: A Comprehensive Review. Ann Pharmacother 2011; 45:60-77. [DOI: 10.1345/aph.1p459] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Objective To provide a comprehensive review of the pharmacotherapy associated with the provision of mechanical circulatory support (MCS) to patients with end-stage heart failure and guidance regarding the selection, assessment, and optimization of drug therapy for this population. Data Sources: The MEDLINE/PubMed, EMBASE, and Cochrane databases were searched from 1960 to July 2010 for articles published in English using the search terms mechanical circulatory support, ventricular assist system, ventricular assist device, left ventricular assist device, right ventricular assist device, biventricular assist device, total artificial heart, pulsatile, positive displacement, axial, centrifugal, hemostasis, bleeding, hemodynamic, blood pressure, thrombosis, antithrombotic therapy, anticoagulant, antiplatelet, right ventricular failure, ventricular arrhythmia, anemia, arteriovenous malformation, stroke, infection, and clinical pharmacist. Study Selection And Data Extraction: All relevant original studies, metaanalyses, systematic reviews, guidelines, and reviews were assessed for inclusion. References from pertinent articles were examined for content not found during the initial search. Data Synthesis: MCS has advanced significantly since the first left ventricular assist device was implanted in 1966. Further advancements in MCS technology that occurred in the tatter decade are changing the overall management of end-stage heart failure care and cardiac transplantation. These pumps allow for improved bridge-to-transplant rates, enhanced survival, and quality of life. Pharmacotherapy associated with MCS devices may optimize the performance of the pumps and improve patient outcomes, as well as minimize morbidity related to their adverse effects. This review highlights the knowledge needed to provide appropriate clinical pharmacy services for patients supported by MCS devices. Conclusions: The HeartMate II clinical investigators called for the involvement of pharmacists in MCS patient assessment and optimization. Pharmacotherapeutic management of patients supported with MCS devices requires individualized care, with pharmacists as part of the team, based on the characteristics of each pump and recipient.
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Affiliation(s)
- Christopher R Ensor
- Cardiothoracic Transplantation and Mechanical Circulatory Support; Clinical Assistant Professor, School of Pharmacy, University of Maryland; Department of Pharmacy, Comprehensive Transplant Center, The Johns Hopkins Hospital, Baltimore, MD
| | - Christopher A Paciullo
- Cardiothoracic Surgery Critical Care, Department of Pharmacy, Emory University Hospital, Atlanta, GA
| | - William D Cahoon
- Cardiology; Clinical Assistant Professor, School of Pharmacy, Virginia Commonwealth University, Virginia Commonwealth University Health System; Department of Pharmacy, Medical College of Virginia Hospitals, Richmond, VA
| | - Paul E Nolan
- College of Pharmacy, University of Arizona; Senior Clinical Scientist, The University Medical Center, Tucson, AZ
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Hematologic effects of continuous flow left ventricular assist devices. J Cardiovasc Transl Res 2010; 3:618-24. [PMID: 20835786 DOI: 10.1007/s12265-010-9222-6] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 08/30/2010] [Indexed: 12/16/2022]
Abstract
The extent of hematologic effects of the new continuous flow left ventricular assist devices (CF-LVAD) has not been studied. Recent clinical studies have demonstrated that hemolysis and thrombosis are not common during CF-LVAD support, however, the incidence of bleeding remains a concern. The rate of postoperative bleeding is similar to that of the prior generation pulsatile LVAD, but gastrointestinal bleeding due to angiodysplasia and arteriovenous malformations is more common and appears to be related to the blood flow rheology of these devices. New evidence suggests that acquired von Willebrand's disease develops in some patients due to the reduction in high molecular weight (HMW) multimers of von Willebrand's factor (vWF). Similar to acquired von Willebrand's disease seen in patients with aortic stenosis, the shear stress of the CF-LVAD may cause proteolysis of the HMW multimers of vWF. In addition to acquired von Willebrand's disease, there is activation of the fibrinolytic system and a loss of platelet numbers and function during CF-LVAD support. The hematologic responses during CF-LVAD support are constantly changing, and antiplatelet therapy may need to be adjusted accordingly. Considerable research is needed to better define the complex hematologic effects during CF-LVAD support. Screening of patients for angiodysplasia and von Willebrand's disease before CF-LVAD implant may allow for effective preemptive treatment. Because bleeding causes significant morbidity for this population, more effective treatment strategies need to be developed.
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Nguyen DQ, Thourani VH. Third-Generation Continuous Flow Left Ventricular Assist Devices. INNOVATIONS-TECHNOLOGY AND TECHNIQUES IN CARDIOTHORACIC AND VASCULAR SURGERY 2010. [DOI: 10.1177/155698451000500402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Duc Q. Nguyen
- Division of Cardiothoracic Surgery, Joseph B. Whitehead Department of Surgery, Emory University School of Medicine, Atlanta, GA USA
| | - Vinod H. Thourani
- Division of Cardiothoracic Surgery, Joseph B. Whitehead Department of Surgery, Emory University School of Medicine, Atlanta, GA USA
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Rogers JG, Aaronson KD, Boyle AJ, Russell SD, Milano CA, Pagani FD, Edwards BS, Park S, John R, Conte JV, Farrar DJ, Slaughter MS. Continuous flow left ventricular assist device improves functional capacity and quality of life of advanced heart failure patients. J Am Coll Cardiol 2010; 55:1826-34. [PMID: 20413033 DOI: 10.1016/j.jacc.2009.12.052] [Citation(s) in RCA: 456] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Revised: 12/18/2009] [Accepted: 12/21/2009] [Indexed: 02/06/2023]
Abstract
OBJECTIVES This study sought to assess the impact of continuous flow left ventricular assist devices (LVADs) on functional capacity and heart failure-related quality of life. BACKGROUND Newer continuous-flow LVAD are smaller and quieter than pulsatile-flow LVADs. METHODS Data from advanced heart failure patients enrolled in the HeartMate II LVAD (Thoratec Corporation, Pleasanton, California) bridge to transplantation (BTT) (n = 281) and destination therapy (DT) (n = 374) trials were analyzed. Functional status (New York Heart Association [NYHA] functional class, 6-min walk distance, patient activity scores), and quality of life (Minnesota Living With Heart Failure [MLWHF] and Kansas City Cardiomyopathy Questionnaires [KCCQ]) were collected before and after LVAD implantation. RESULTS Compared with baseline, LVAD patients demonstrated early and sustained improvements in functional status and quality of life. Most patients had NYHA functional class IV symptoms at baseline. Following implant, 82% (BTT) and 80% (DT) of patients at 6 months and 79% (DT) at 24 months improved to NYHA functional class I or II. Mean 6-min walk distance in DT patients was 204 m in patients able to ambulate at baseline, which improved to 350 and 360 m at 6 and 24 months. There were also significant and sustained improvements from baseline in both BTT and DT patients in median MLWHF scores (by 40 and 42 U in DT patients, or 52% and 55%, at 6 and 24 months, respectively), and KCCQ overall summary scores (by 39 and 41 U, or 170% and 178%). CONCLUSIONS Use of a continuous flow LVAD in advanced heart failure patients results in clinically relevant improvements in functional capacity and heart failure-related quality of life.
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Alba AC, Delgado DH. The future is here: ventricular assist devices for the failing heart. Expert Rev Cardiovasc Ther 2009; 7:1067-77. [PMID: 19764860 DOI: 10.1586/erc.09.86] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mechanical circulatory support is an important adjunct to the management of patients with advanced heart failure. Technological advances in this area have improved overall survival and decreased the incidence of complications. In addition, they have expanded the population suitable for this therapy. The challenge for clinicians is to translate the clinical evidence into the selection of the most appropriate device that will benefit an individual patient. This paper will review ventricular assist devices currently available and their clinical indications.
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Affiliation(s)
- Ana C Alba
- Heart Failure and Transplantation, University Health Network, NCSB 11C-1201, 585 University Avenue, Toronto, ON, M5G 2N2, Canada.
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Ye SH, Johnson CA, Woolley JR, Oh HI, Gamble LJ, Ishihara K, Wagner WR. Surface modification of a titanium alloy with a phospholipid polymer prepared by a plasma-induced grafting technique to improve surface thromboresistance. Colloids Surf B Biointerfaces 2009; 74:96-102. [PMID: 19647420 PMCID: PMC2811089 DOI: 10.1016/j.colsurfb.2009.06.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 06/26/2009] [Accepted: 06/29/2009] [Indexed: 11/29/2022]
Abstract
To improve the thromboresistance of a titanium alloy (TiAl(6)V(4)) surface which is currently utilized in several ventricular assist devices (VADs), a plasma-induced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) was carried out and poly(MPC) (PMPC) chains were covalently attached onto a TiAl(6)V(4) surface by a plasma induced technique. Cleaned TiAl(6)V(4) surfaces were pretreated with H(2)O-vapor-plasma and silanated with 3-methacryloylpropyltrimethoxysilane (MPS). Next, a plasma-induced graft polymerization with MPC was performed after the surfaces were pretreated with Ar plasma. Surface compositions were verified by X-ray photoelectron spectroscopy (XPS). In vitro blood biocompatibility was evaluated by contacting the modified surfaces with ovine blood under continuous mixing. Bulk phase platelet activation was quantified by flow cytometric analysis, and surfaces were observed with scanning electron microscopy after blood contact. XPS data demonstrated successful modification of the TiAl(6)V(4) surfaces with PMPC as evidenced by increased N and P on modified surfaces. Platelet deposition was markedly reduced on the PMPC grafted surfaces and platelet activation in blood that contacted the PMPC-grafted samples was significantly reduced relative to the unmodified TiAl(6)V(4) and polystyrene control surfaces. Durability studies under continuously mixed water suggested no change in surface modification over a 1-month period. This modification strategy shows promise for further investigation as a means to reduce the thromboembolic risk associated with the metallic blood-contacting surfaces of VADs and other cardiovascular devices under development.
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Affiliation(s)
- Sang Ho Ye
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Carl A. Johnson
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Joshua R. Woolley
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Heung-Il Oh
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Lara J. Gamble
- Departments of Bioengineering and NESAC/BIO, University of Washington, Seattle, WA 98195, USA
| | - Kazuhiko Ishihara
- Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - William R. Wagner
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15219, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15219, USA
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Lim KM, Kim IS, Choi SW, Min BG, Won YS, Kim HY, Shim EB. Computational analysis of the effect of the type of LVAD flow on coronary perfusion and ventricular afterload. J Physiol Sci 2009; 59:307-16. [PMID: 19387788 PMCID: PMC10717237 DOI: 10.1007/s12576-009-0037-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 03/29/2009] [Indexed: 11/26/2022]
Abstract
We developed a computational model to investigate the hemodynamic effects of a pulsatile left ventricular assist device (LVAD) on the cardiovascular system. The model consisted of 16 compartments for the cardiovascular system, including coronary circulation and LVAD, and autonomic nervous system control. A failed heart was modeled by decreasing the end-systolic elastance of the ventricle and blocking the mechanism controlling heart contractility. We assessed the physiological effect of the LVAD on the cardiovascular system for three types of LVAD flow: co-pulsation, counter-pulsation, and continuous flow modes. The results indicated that the pulsatile LVAD with counter-pulsation mode gave the most physiological coronary blood perfusion. In addition, the counter-pulsation mode resulted in a lower peak pressure of the left ventricle than the other modes, aiding cardiac recovery by reducing the ventricular afterload. In conclusion, these results indicate that, from the perspective of cardiovascular physiology, a pulsatile LVAD with counter-pulsation operation is a plausible alternative to the existing LVAD with continuous flow mode.
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Affiliation(s)
- Ki Moo Lim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Hyoja-dong, Chuncheon, Gangwon-do Republic of Korea
| | - In Su Kim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Hyoja-dong, Chuncheon, Gangwon-do Republic of Korea
| | - Seong Wook Choi
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Hyoja-dong, Chuncheon, Gangwon-do Republic of Korea
| | - Byung Goo Min
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Hyoja-dong, Chuncheon, Gangwon-do Republic of Korea
| | - Yong Soon Won
- Department of Thoracic and Cardiovascular Surgery, College of Medicine, Soonchunhyang University, Bucheon, Gyeonggi-do Republic of Korea
| | - Heon Young Kim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Hyoja-dong, Chuncheon, Gangwon-do Republic of Korea
| | - Eun Bo Shim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Hyoja-dong, Chuncheon, Gangwon-do Republic of Korea
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Sato K, Orihashi K, Kurosaki T, Tokumine A, Fukunaga S, Ninomiya S, Sueda T. Analysis of flow patterns in a ventricular assist device: a comparative study of particle image velocimetry and computational fluid dynamics. Artif Organs 2009; 33:352-9. [PMID: 19335412 DOI: 10.1111/j.1525-1594.2009.00726.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In order to develop a diaphragm-type ventricular assist device (VAD), we studied the flow field change following structural modifications. We devised a center flow-type pump by putting a small projection on the center of the housing and/or diaphragm to provide a center in the flow field, and examined the following four types of VADs: N type without a projection, D type with a projection on the diaphragm, H type with a projection on the housing, and DH type with projections on both the diaphragm and housing. Computational fluid dynamics (CFD) was used for flow simulation. Particle image velocimetry (PIV) was also used to verify the reliability of the CFD method and to determine how the flow field changes in the presence of a projection. The results of the PIV and CFD analyses were comparable. The placement of a projection on the housing was most effective in rectifying the flow field.
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Affiliation(s)
- Katsutoshi Sato
- Department of Surgery, Division of Clinical Medical Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
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Dispositivos de asistencia ventricular de tipo axial. CIRUGIA CARDIOVASCULAR 2009. [DOI: 10.1016/s1134-0096(09)70158-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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In vivo experimental testing of the FW axial blood pump for left ventricular support in Fu Wai Hospital. ASAIO J 2009; 55:28-32. [PMID: 19092667 DOI: 10.1097/mat.0b013e31818f592f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
A fully implantable, axial flow blood pump has been developed in Fu Wai Hospital aiming for clinical use. This ventricular assist device (VAD), which was developed after numerous CFD analyses for the flow characteristics of the pump, is 58.5-mm long, 30-mm wide (including DC motor), and weighs 240 g. The pump can deliver 5 L/min for pressures of 100 mm Hg over 8,000 rpm. In this study, short-term hemocompatibility effects of the axial left ventricular assist device (LVAD) (FW blood pump) were evaluated in four healthy sheep. The device was implanted into the left ventricular apex of beating hearts. The outflow graft of each device was anastomosed to the descending aorta. The hemolysis, which was evaluated in vivo by free hemoglobin value, was below 30 mg/dL. Evaluation of serum biochemical data showed that implantation of the FW blood pump in sheep with normal hearts did not impair end organ function. Gross and microscopic sections of kidney, liver, and lung revealed no evidence of microemboli. Performance of the pump in vivo was considered sufficient for a LVAD, although further design improvement is necessary in terms of hemolysis and antithrombosis to improve biocompatibility of the pump.
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Hernandez AF, Shea AM, Milano CA, Rogers JG, Hammill BG, O'Connor CM, Schulman KA, Peterson ED, Curtis LH. Long-term outcomes and costs of ventricular assist devices among Medicare beneficiaries. JAMA 2008; 300:2398-406. [PMID: 19033590 PMCID: PMC2629048 DOI: 10.1001/jama.2008.716] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
CONTEXT In 2003, Medicare expanded coverage of ventricular assist devices as destination, or permanent, therapy for end-stage heart failure. Little is known about the long-term outcomes and costs associated with these devices. OBJECTIVE To examine the acute and long-term outcomes of Medicare beneficiaries receiving ventricular assist devices alone or after open-heart surgery. DESIGN, SETTING, AND PATIENTS Analysis of inpatient claims from the Centers for Medicare & Medicaid Services for the period 2000 through 2006. Patients were Medicare fee-for-service beneficiaries who received a ventricular assist device between February 2000 and June 2006 alone as primary therapy (primary device group; n = 1476) or after cardiotomy in the previous 30 days (postcardiotomy group; n = 1467). MAIN OUTCOME MEASURES Cumulative incidence of device replacement, device removal, heart transplantation, readmission, and death, accounting for censoring and competing risks. Patients were followed up for at least 6 months and factors independently associated with long-term survival were identified. Medicare payments were used to calculate total inpatient costs and costs per day outside the hospital. RESULTS Overall 1-year survival was 51.6% (n = 669) in the primary device group and 30.8% (n = 424) in the postcardiotomy group. Among primary device patients, 815 (55.2%) were discharged alive with a device. Of those, 450 (55.6%) were readmitted within 6 months and 504 (73.2%) were alive at 1 year. Of the 493 (33.6%) postcardiotomy patients discharged alive with a device, 237 (48.3%) were readmitted within 6 months and 355 (76.6%) were alive at 1 year. Mean 1-year Medicare payments for inpatient care for patients in the 2000-2005 cohorts were $178,714 (SD, $142,549) in the primary device group and $111,769 (SD, $95,413) in the postcardiotomy group. CONCLUSIONS Among Medicare beneficiaries receiving a ventricular assist device, early mortality, morbidity, and costs remain high. Improving patient selection and reducing perioperative mortality are critical for improving overall outcomes.
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Abstract
Mechanical circulatory support is becoming an alternative therapeutic option for patients in cardiogenic shock or advanced cardiac failure who cannot be improved by maximal medical therapy. More than 30 years of engineering development and clinical research have led to a level of efficacy and reliability of ventricular assist devices, which allows promotion of this approach for the most difficult patients. Uses include a gaining-time strategy as a bridge to cardiac transplantation or recovery of native cardiac function, as well as permanent support with the device. The large variety of devices permits every cardiac surgical unit, even those not used to cardiac transplantation, to propose this option to the patient. Recent experience with small silent implantable pumps suggests that the pioneering period of mechanical circulatory support is probably over, and the time has come for precise prospective trials to optimize both patient selection and the timing for utilization. In countries where cardiac transplantation has not developed, there is now an easily accessible technique for management of patients with cardiac failure.
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Affiliation(s)
- Daniel Loisance
- Hôpital Henri Mondor, Service de Chirurgie Thoracique et Cardiovasculaire, 51 Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France.
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Mechanical Circulatory Device Thrombosis: A New Paradigm Linking Hypercoagulation and Hypofibrinolysis. ASAIO J 2008; 54:351-8. [DOI: 10.1097/mat.0b013e31817f3e03] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Frazier OH, Jacob LP. Small pumps for ventricular assistance: progress in mechanical circulatory support. Cardiol Clin 2008; 25:553-64; vi. [PMID: 18063159 DOI: 10.1016/j.ccl.2007.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Compared with earlier models, current pumps are much smaller, simpler, and more efficient, offering long-term or even permanent support. They fit a wider size range of patients and are less invasive to implant. Because they have few moving parts, they are less susceptible to infection and failure. Additionally, they offer much greater patient comfort, allowing a relatively normal lifestyle. This article focuses on the current state of continuous-flow pumps for both temporary and long-term use in treating acute and chronic heart failure.
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Affiliation(s)
- O H Frazier
- Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX, USA.
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Miller LW, Pagani FD, Russell SD, John R, Boyle AJ, Aaronson KD, Conte JV, Naka Y, Mancini D, Delgado RM, MacGillivray TE, Farrar DJ, Frazier OH. Use of a continuous-flow device in patients awaiting heart transplantation. N Engl J Med 2007; 357:885-96. [PMID: 17761592 DOI: 10.1056/nejmoa067758] [Citation(s) in RCA: 1355] [Impact Index Per Article: 75.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND The use of left ventricular assist devices is an accepted therapy for patients with refractory heart failure, but current pulsatile volume-displacement devices have limitations (including large pump size and limited long-term mechanical durability) that have reduced widespread adoption of this technology. Continuous-flow pumps are newer types of left ventricular assist devices developed to overcome some of these limitations. METHODS In a prospective, multicenter study without a concurrent control group, 133 patients with end-stage heart failure who were on a waiting list for heart transplantation underwent implantation of a continuous-flow pump. The principal outcomes were the proportions of patients who, at 180 days, had undergone transplantation, had cardiac recovery, or had ongoing mechanical support while remaining eligible for transplantation. We also assessed functional status and quality of life. RESULTS The principal outcomes occurred in 100 patients (75%). The median duration of support was 126 days (range, 1 to 600). The survival rate during support was 75% at 6 months and 68% at 12 months. At 3 months, therapy was associated with significant improvement in functional status (according to the New York Heart Association class and results of a 6-minute walk test) and in quality of life (according to the Minnesota Living with Heart Failure and Kansas City Cardiomyopathy questionnaires). Major adverse events included postoperative bleeding, stroke, right heart failure, and percutaneous lead infection. Pump thrombosis occurred in two patients. CONCLUSIONS A continuous-flow left ventricular assist device can provide effective hemodynamic support for a period of at least 6 months in patients awaiting heart transplantation, with improved functional status and quality of life. (ClinicalTrials.gov number, NCT00121472 [ClinicalTrials.gov].).
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Remmelink M, Sjauw KD, Henriques JPS, de Winter RJ, Koch KT, van der Schaaf RJ, Vis MM, Tijssen JGP, Piek JJ, Baan J. Effects of left ventricular unloading by Impella recover LP2.5 on coronary hemodynamics. Catheter Cardiovasc Interv 2007; 70:532-7. [PMID: 17896398 DOI: 10.1002/ccd.21160] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVES We studied the effects of LV unloading by the Impella on coronary hemodynamics by simultaneously measuring intracoronary pressure and flow and the derived parameters fractional flow reserve (FFR), coronary flow velocity reserve (CFVR), and coronary microvascular resistance (MR). BACKGROUND Patients with compromised left ventricular (LV) function undergoing high-risk percutaneous coronary intervention (PCI) may benefit from LV unloading. Limited information is available on the effects of LV unloading on coronary hemodynamics. METHODS Eleven patients (mean LV ejection fraction of 35 +/- 11%) underwent PCI during LV support by the LV unloading device (Impella Recover LP2.5). Intracoronary measurements were performed in a nonstenotic coronary artery after the PCI, before and after adenosine-induced hyperemia at four different support levels (0-2.5 L/min). RESULTS Aortic and coronary pressure increased with increasing support levels, whereas FFR remained unchanged. Baseline flow velocity remained unchanged, while hyperemic flow velocity and CFVR increased significantly with increasing support levels (61 +/- 24 to 72 +/- 27 cm/sec, P = 0.001 and 1.88 +/- 0.52 to 2.34 +/- 0.63, P < 0.001 respectively). The difference between baseline MR and hyperemic MR significantly increased with increasing support levels (1.28 +/- 1.32 to 1.89 +/- 1.43 mm Hg cm(-1) sec, P = 0.005). CONCLUSIONS Unloading of the LV by the Impella increased aortic and intracoronary pressure, hyperemic flow velocity and CFVR, and decreased MR. The Impella-induced increase in coronary flow, probably results from both an increased perfusion pressure and a decreased LV volume-related intramyocardial resistance.
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Affiliation(s)
- Maurice Remmelink
- Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Abstract
OBJECTIVE Mechanical support of the circulation is necessary when heart failure becomes refractory to medical support and is typically applied when organ dysfunction occurs as a result of hypoperfusion. However, in timing the intervention, it is important to apply mechanical support before multiple organ failure occurs. The objective of this work is to review the current strategies for mechanical circulatory support in patients with refractory cardiac failure. DESIGN A review of the use of mechanical circulatory support is presented for patients with refractory cardiac failure. PATIENTS Data are taken from human studies that were selected to best exemplify the results that may be obtained from various forms of mechanical circulatory support. INTERVENTIONS Commonly applied forms of mechanical support include mechanical ventilatory support, intraaortic balloon counterpulsation, and hemodialysis or ultrafiltration. If these measures fail, mechanical support of the circulation with ventricular assist devices is possible in specialized centers with expertise in the implantation and management of these devices. The decision to pursue mechanical circulatory support in the critically ill patient is based on the cause of acute decompensation, the potential reversibility of the condition, and the possibility for other treatments to improve the underlying condition or, in highly selected cases, heart transplantation. Newer forms of ventricular assistance that require less surgery are becoming available and may allow use in a broader range of critically ill patients. MAIN RESULTS There is a range of means to mechanically support the circulation in patients with advanced heart failure. CONCLUSIONS A variety of means to support the circulation have found application in the treatment of patients with refractory heart failure. More work is required to best identify populations who will benefit from the therapy and to refine the therapy to reduce associated risks.
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Affiliation(s)
- John P Boehmer
- Department of Medicine, The Pennsylvania State University College of Medicine, The Penn State Hershey Medical Center, Hershey, PA, USA
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Catena E, Milazzo F, Montorsi E, Bruschi G, Cannata A, Russo C, Barosi A, Tarelli G, Tartara P, Paino R, Vitali E. Left ventricular support by axial flow pump: the echocardiographic approach to device malfunction. J Am Soc Echocardiogr 2006; 18:1422. [PMID: 16376778 DOI: 10.1016/j.echo.2005.04.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2005] [Indexed: 11/28/2022]
Abstract
Axial flow pumps have gained increased acceptance in recent years as a bridge to heart transplantation and, more recently, as destination therapy. As left ventricular (LV) assist device dysfunction will be increasingly prevalent, the aim of our work was to introduce an echocardiographic management protocol as a guide to recognize the causes of pump failure. In this article we describe the echocardiographic approach to 5 episodes of malfunction of an axial flow pump (DeBakey, MicroMed Technology Inc, Houston, Tex) in 4 patients: 4 episodes caused by thrombosis of LV assist device and one caused by abnormal increase of systemic vascular resistance. In our experience, echocardiography played a pivotal role in clinical management of LV assist device failure. It allowed us to: assess patency and position of inflow and outflow cannulae; research the source of thromboembolic material; assess adequate LV filling and unloading; and optimize right ventricular function, volume replacement therapy, and pharmacologic support.
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Affiliation(s)
- Emanuele Catena
- Division of Cardiothoracic Anesthesia and Intensive Care, Department of Cardio-Thoracic Surgery A. De Gasperis, Niguarda Cà Granda Hospital, Milan, Italy.
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Minden HH, Lehmann H, Meyhöfer J, Butter C. Transradial unprotected left main coronary stenting supported by percutaneous Impella® Recover LP 2.5 assist device. Clin Res Cardiol 2006; 95:301-6. [PMID: 16598397 DOI: 10.1007/s00392-006-0371-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 01/23/2006] [Indexed: 10/24/2022]
Abstract
Percutaneous coronary intervention (PCI) has been increasingly applied to patients with severely depressed left ventricular function and complex coronary lesions. The availability of hemodynamic support devices offers a promising option to reduce PCI-related complications in high-risk procedures. We report the case of a 79-year-old man who suffered from unstable angina. The coronary angiogram revealed multivessel disease including a significant distal left main (LM) stenosis. Additionally, the patient had a history of chronic lymphatic leukemia with immune hemolysis. Therefore, the patient was considered to be at exceptionally high mortality risk in case of cardiac surgery. We decided to perform a percutaneous revascularization of the LM supported by the Impella Recover LP 2.5 assist device. This case report discusses the principles of indications, technique and complications of this new addition to interventional cardiology.
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Affiliation(s)
- H H Minden
- Immanuel Diakonie Group, Heart Center Brandenburg in Bernau, Department of Cardiology, Bernau, Germany.
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Holman WL, Pamboukian SV, Blood M, Tallaj JA, McGiffin DC, Kirklin JK. Managing Device Infections: Are We Progressing or Is Infection an Insurmountable Obstacle? ASAIO J 2005; 51:452-5. [PMID: 16156312 DOI: 10.1097/01.mat.0000169120.48527.87] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
This article reviews infections that occur in patients with implanted mechanical circulatory support devices and presents recent data for signs of progress in controlling the incidence and impact of these infections. Two types of comparisons are used to examine this question. First, the outcomes of patients with HeartMate vented electric left ventricular assist devices (VADs) (Thoratec Corp, Pleasanton, CA) implanted during the REMATCH Trial are compared with the outcome of more recent patients who received this pump as destination therapy. Second, the outcome of patients who received a smaller left VAD (e.g., an axial flow VAD) or a fully implanted left VAD are reported and contrasted with results from the REMATCH era. Data are presented to support the hypothesis that improvements in patient selection, patient management, device durability, and device design have resulted in lower rates of infection and infection-related death for patients who require mechanical circulatory support.
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Affiliation(s)
- William L Holman
- Department of Surgery, University of Alabama at Birmingham, Birmingham AL, USA
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Patel SM, Throckmorton AL, Untaroiu A, Allaire PE, Wood HG, Olsen DB. The Status of Failure and Reliability Testing of Artificial Blood Pumps. ASAIO J 2005; 51:440-51. [PMID: 16156311 DOI: 10.1097/01.mat.0000169083.90253.3c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Artificial blood pumps are today's most promising bridge-to-transplant, bridge-to-recovery, and destination therapy solutions for patients with congestive heart failure. There is a critical need for increased reliability and safety as the next generation of artificial blood pumps approach final development for long-term destination therapy. To date, extensive failure and reliability studies of these devices are considered intellectual property and thus remain unpublished. Presently, the Novacor N100PC, Thoratec VAD, and HeartMate LVAS (IP and XVE) comprise the only four artificial blood pumps commercially available for the treatment of congestive heart failure in the United States. The CardioWest TAH recently received premarket approval from the US Food and Drug Administration. With investigational device exemptions, the AB-180, AbioCor, LionHeart, DeBakey, and Flowmaker are approved for clinical testing. Other blood pumps, such as the American BioMed-Baylor TAH, CorAide, Cleveland Clinic-Nimbus TAH, HeartMate III, Hemadyne, and MagScrew TAH are currently in various stages of mock loop and animal testing, as indicated in published literature. This article extensively reviews in vitro testing, in vivo testing, and the early clinical testing of artificial blood pumps in the United States, as it relates to failure and reliability. This detailed literature review has not been published before and provides a thorough documentation of available data and testing procedures regarding failure and reliability of these various pumps.
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Affiliation(s)
- Sonna M Patel
- Department of Biomedical Engineering University of Virginia, Charlottesville, VA, USA
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Voigt O, Benkowski RJ, Morello GF. Suction Detection for the MicroMed DeBakey Left Ventricular Assist Device. ASAIO J 2005; 51:321-8. [PMID: 16156293 DOI: 10.1097/01.mat.0000169118.21639.da] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The MicroMed DeBakey Ventricular Assist Device (MicroMed Technology, Inc., Houston, TX) is a continuous axial flow pump designed for long-term circulatory support. The system received CE approval in 2001 as a bridge to transplantation and in 2004 as an alternative to transplantation. Low volume in the left ventricle or immoderate pump speed may cause ventricular collapse due to excessive suction. Suction causes decreased flow and may result in patient discomfort. Therefore, detection of this critical condition and immediate adaptive control of the device is desired. The purpose of this study is to evaluate and validate system parameters suitable for the reliable detection of suction. In vitro studies have been performed with a mock loop allowing pulsatile and nonpulsatile flow. Evidence of suction is clearly shown by the flow waveform reported by the implanted flow probe of the system. For redundancy to the implanted flow probe, it would be desirable to use the electronic motor signals of the pump for suction detection. The continuously accessible signals are motor current consumption and rotor/impeller speed. The influence of suction on these parameters has been investigated over a wide range of hydrodynamic conditions, and the significance of the respective signals individually or in combination has been explored. The reference signal for this analysis was the flow waveform of the ultrasonic probe. To achieve high reliability under both pulsatile and nonpulsatile conditions, it was determined that motor speed and current should be used concurrently for suction detection. Using the amplified differentiated current and speed signals, a suction-detection algorithm has been optimized, taking into account two different working points, defined by the value of the current input. The safety of this algorithm has been proven in vitro under pulsatile and nonpulsatile conditions over the full spectrum of possible speed and differential pressure variations. The algorithm described herein may be best utilized to provide redundancy to the existing flow based algorithm.
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Takatani S, Matsuda H, Hanatani A, Nojiri C, Yamazaki K, Motomura T, Ohuchi K, Sakamoto T, Yamane T. Mechanical circulatory support devices (MCSD) in Japan: current status and future directions. J Artif Organs 2005; 8:13-27. [PMID: 15951976 DOI: 10.1007/s10047-004-0284-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2004] [Indexed: 10/25/2022]
Abstract
The current status and future directions of mechanical circulatory support devices (MCSDs) in Japan are reviewed. Currently used clinical MCSDs, both domestic and imported systems and continuous flow devices that are coming into the clinical arena are emphasized. Clinical MCSDs include the extracorporeal pulsatile Toyobo and Zeon systems and the implantable Novacor and HeartMate I VE. A thorough review is presented of single-ventricle continuous flow MCSDs such as the Terumo DuraHeart and the SunMedical EVAHEART and the biventricular Miwatec/Baylor systems that are on the horizon. The future directions in management of end-stage cardiac patients with MCSDs are discussed, focusing on (1) device selection - pulsatile versus continuous flow devices; (2) single-ventricle support, biventricular support, or replacement; (3) bridge to transplantation, destination therapy, or bridge to recovery; and (4) government regulatory processes and the medical industry. We hope to promote the quality of life (QOL) of end-stage cardiac patients as well as the medical industry in Japan.
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Affiliation(s)
- Setsuo Takatani
- Department of Artificial Organs, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Surugadai, Kanda, Chiyoda-ku, Tokyo, 101-0062, Japan.
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Watanabe N, Masuda T, Iida T, Kataoka H, Fujimoto T, Takatani S. Quantification of the Secondary Flow in a Radial Coupled Centrifugal Blood Pump Based on Particle Tracking Velocimetry. Artif Organs 2005; 29:26-35. [PMID: 15644080 DOI: 10.1111/j.1525-1594.2004.29012.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Secondary flow in the centrifugal blood pump helps to enhance the washout effect and to minimize thrombus formation. On the other hand, it has an adverse effect on pump efficiency. Excessive secondary flow may induce hemolytic effects. Understanding the secondary flow is thus important to the design of a compact, efficient, biocompatible blood pump. This study examined the secondary flow in a radial coupled centrifugal blood pump based on a simple particle tracking velocimetry (PTV) technique. A radial magnetically coupled centrifugal blood pump has a bell-shaped narrow clearance between the impeller inner radius and the pump casing. In order to vary the flow levels through the clearance area, clearance widths of 0.25 mm and 0.50 mm and impeller washout holes with diameters of 0 mm, 2.5 mm, and 4 mm were prepared. A high-speed video camera (2000 frames per second) was used to capture the particle images from which radial flow components were derived. The flow in the space behind the impeller was assumed to be laminar and Couette type. The larger the inner clearance or diameter of washout hole, the greater was the secondary flow rate. Without washout holes, the flow behind the impeller resulted in convection. The radial flow through the washout holes of the impeller was conserved in the radial as well as in the axial direction behind the impeller. The increase in the secondary flow reduced the net pump efficiency. Simple PTV was successful in quantifying the flow in the space behind the impeller. The results verified the hypothesis that the flow behind the impeller was theoretically Couette along the circumferential direction. The convection flow observed behind the impeller agreed with the reports of other researchers. Simple PTV was effective in understanding the fluid dynamics to help improve the compact, efficient, and biocompatible centrifugal blood pump for safe clinical applications.
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Affiliation(s)
- Nobuo Watanabe
- Department of Artificial Organs, Institute of Biomaterial and Bioengineering, Tokyo Medical and Dental University, Chiyoda-ku, Tokyo, Japan
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Nam KW, Chung J, Choi SW, Kim WE, Sun K, Min BG. Development of counterpulsation algorithm for a moving-actuator type pulsatile LVAD. Int J Artif Organs 2004; 27:882-90. [PMID: 15560682 DOI: 10.1177/039139880402701009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A pulsatile left ventricular assist device (LVAD) was used to support the aortic blood pumping function of an injured left ventricle, and as a result helped its recovery. It is important to observe a left ventricle's pumping status and to adjust the operating status of a LVAD to reduce the left ventricle's pumping load and thus to enhance its recovery. To observe the left ventricle's pumping status, an electrocardiogram (ECG) signal is generally used because it is a result of the natural heart's blood pumping function. In this paper, we describe the development of an ECG based counterpulsation control algorithm that prevents simultaneous aortic blood co-pumping by a left ventricle and a moving-actuator type pulsatile LVAD and as a result, reduces the natural heart's pumping load. In addition, to verify the algorithm's applicability for LVAD control we designed three ECG based automatic pump control algorithms that use a developed counterpulsation control algorithm. These algorithms control the operating status of a LVAD automatically and, at the same time, maintain a counterpulsing status. The results of in vitro experiments show that the counterpulsing effect between a left ventricle and a LVAD was successfully produced and that the newly designed automatic pump control algorithms met their own control purposes with a counterpulsing effect.
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Affiliation(s)
- K W Nam
- Interdisciplinary Program of Medical and Biological Engineering Major, Seoul National University, Seoul - Korea
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