The presence of coronary tandem lesions poses a significant challenge for the accurate diagnosis and management of coronary artery diseases. This study set out to provide a deeper understanding of the haemodynamic interactions between tandem obstructive coronary lesions and their impact on different haemodynamic diagnostic parameters. Using a computational fluid dynamic model, validated against in vitro laboratory experiments, we investigated the various combinations of moderate and severe stenoses interchangeably located in the proximal and distal segments of the artery. The investigation was conducted using two diagnostic parameters: one hyperaemic-based, i.e., FFR, and one rest-based, i.e., iFR, technique, both of which are commonly used to assess the physiological significance of coronary stenoses. The three main findings of this work are: (a) the recovery distance (the immediate local distance affected by the presence of stenosis) is much shorter for the rest-measured diagnostic parameter compared with the hyperaemic-measured diagnostic parameter; (b) pressure drop measurements immediately downstream of the stenotic sections overestimate the significance of stenoses, and (c) the presence of a moderate stenosis downstream of a severe stenosis increases FFR value (faster FFR recovery). These findings enhance our understanding of the diagnostic accuracy of hyperaemic-based and rest-based physiological diagnostic coronary assessments and the nuances of using these different techniques when assessing tandem coronary stenoses. This understanding can help inform tailored therapeutic approaches for the management of coronary artery disease.

Revascularization decision-making for saphenous vein grafts (SVGs) relies on angiographic lesion severity estimation, as studies on fractional flow reserve (FFR) for detecting ischemia in SVGs are scarce.

To compare FFR and quantitative coronary angiography (QCA) of SVGs against myocardial perfusion imaging (MPI) and to establish an optimal FFR threshold for SVGs.

This cross-sectional registry study included symptomatic patients with prior coronary artery bypass grafting who underwent single-photon emission computed tomography, positron emission tomography, or stress perfusion cardiac magnetic resonance imaging and had FFR measurements of ≥ 1 SVGs. We matched the myocardial territory supplied by the SVGs to ischemia on MPI. The optimal FFR threshold for SVGs was determined using the Youden index. Diagnostic performance measures were calculated and compared for FFR (0.80 and the optimal threshold) and for QCA (diameter stenosis ≥ 50%).

This study included 80 patients (mean age 73 ± 7 years, 68 [85%] male) with 94 SVGs, of which 38 (40%) supplied ischemic myocardium. Areas under the curve between FFR and QCA were comparable (0.73 vs. 0.65, p = 0.181). The optimal cutoff value of FFR was 0.94. FFR ≤ 0.94 showed higher sensitivity (63%) and negative predictive value (75%) compared to FFR ≤ 0.80 (32% [p < 0.001] and 64% [p = 0.007]) and QCA (37% [p = 0.002] and 65% [p = 0.021]), but with lower specificity (75%) than FFR ≤ 0.80 (84%, p = 0.021). Positive predictive value and overall accuracy were similar across all methods.

FFR and QCA had comparable moderate diagnostic performance for detecting SVG failure determined by MPI. The optimal FFR cutoff in SVGs is higher than 0.80, resulting in higher sensitivity and negative predictive value compared to FFR ≤ 0.80 and QCA, at the expense of reduced specificity.

Optimizing decision-making remains essential in the management of stable coronary artery disease (CAD). Recent studies of the pullback pressure gradient (PPG), a novel tool for evaluating CAD patterns, have demonstrated that the effectiveness of percutaneous coronary intervention (PCI) is strongly influenced by the baseline CAD pattern (focal vs diffuse). The capacity of PPG to predict the success of PCI provides a means to better inform decision-making, revascularization strategies and, potentially, improve clinical outcomes.

Vascular steal refers to the diversion of blood flow between collateral vessels that share a common inflow restricted by arterial stenosis. Blood is diverted from the high-pressure to the low-pressure, low-resistance system. Vascular steal is associated with anatomical bypass or vasodilation in the collateral network and is called "the arterial steal". However, we have demonstrated that in the presence of an outflow gradient (e.g., intra-extracranial), blood is shunted to a lower pressure system, a phenomenon we term "venous steal". Using Thevenin's equivalent, we generalized the concept of venous steal to apply it to any region of the vascular system with increased outflow pressure. Both arterial steal, caused by increased collateral network conductivity, and venous steal, resulting from lower collateral outflow pressure, reduce compartment perfusion. This occurs indirectly by increasing flow and the pressure gradient across the arterial stenosis, lowering the segmental compartment perfusion pressure-the difference between post-stenotic (inflow) and compartmental (outflow) pressures. Venous steal diverts blood flow from compartments with elevated pressure, such as intracranial, subendocardial, the ischemic core, and regions of focal edema due to inflammation, trauma, or external compression. In shock and low-flow states, it contributes to regional blood flow maldistribution. Treatment of venous steal addresses inflow stenosis, increased compartmental pressure and systemic loading conditions (arterial and venous pressure) to reverse venous steal malperfusion in the ischemic regions.

Coronary heart disease (CHD) is one of the leading causes of mortality worldwide. It is primarily caused by myocardial ischemia and hypoxia resulting from atherosclerotic plaques in the coronary arteries, leading to symptoms such as angina. The severity of CHD determines the treatment approach, which may include medication or interventional therapy. Therefore, accurately assessing the severity of myocardial ischemia is crucial for effective CHD management. In recent years, fractional flow reserve (FFR), derived from the relationship between flow and pressure, has gained widespread recognition for providing valuable information to guide coronary revascularization. Pressure guidewires equipped with pressure sensors at their tips are the most commonly used tools for clinical FFR assessment. These wires measure vessel pressure to determine the severity of coronary lesions. However, during their use, issues such as signal drift, tip breakage, core wire fractures, and coating detachment may occur. This article reviews the historical development of pressure guidewires, examines the general structure of two commonly used pressure guidewires available in the market, highlights typical issues encountered during clinical use, and proposes corresponding solutions.

Monocytes are heterogeneous immune cells that play a crucial role in the inflammatory response during atherosclerosis, influencing the progression and outcome of the disease. In the pathogenesis of atherosclerotic diseases, such as coronary artery disease (CAD), monocytes not only serve as the initial sensors of endogenous and exogenous pathogenic factors, but also function as intermediators that bridge the circulatory system and localized lesions. In the bloodstream, heterogeneous monocytes, acting as sentinels, are rapidly recruited to atherosclerotic lesions, where they exhibit a heightened capacity to respond to various pathological stimuli upon detecting signals from damaged vascular endothelial cells. Clinical studies have demonstrated that the heterogeneity of monocytes in CAD patients presents both diversity and complexity, varying across different disease subtypes and pathological stages. This review explores the heterogeneity of monocytes in CAD, focusing on alterations in monocyte subset numbers, proportions, and the expression of functional receptors, as well as their correlations with clinical features. Additionally, we propose strategies to enhance the clinical utility value of monocyte heterogeneity and outline future research directions in the field of CAD. With the widespread application of high-parameter flow cytometry and single-cell sequencing technologies, it is anticipated that a comprehensive understanding of monocyte heterogeneity in CAD will be achieved, enabling the identification of disease-specific monocyte subtypes. This could offer new opportunities for improving the diagnosis and treatment of CAD.

Safe deferral of revascularisation is a key aspect of physiology-guided percutaneous coronary intervention (PCI). While recent evidence gathered in the FAVOR III Europe trial showed that quantitative flow ratio (QFR) guidance did not meet non-inferiority to fractional flow reserve (FFR) guidance, it remains unknown if QFR might have a specific value in revascularisation deferral.

We aimed to evaluate the safety of coronary revascularisation deferral based on QFR as compared with FFR.

Patients randomised in the FAVOR III trial in whom PCI was deferred in at least one coronary artery, based on QFR or FFR>0.80, were included in the present substudy. The primary outcome was the 1-year rate of major adverse cardiac events (MACE), with results reported for two subsets of deferred patients: (1) any study lesion deferral and (2) complete study lesion deferral.

A total of 523 patients (55.2%) in the QFR group and 599 patients (65.3%) in the FFR group had at least one coronary revascularisation deferral. Of these, 433 patients (82.8%) and 511 (85.3%) patients, respectively, had complete study lesion deferral. In the "complete study lesion deferral" patient group, the occurrence of MACE was significantly higher in QFR-deferred patients as compared with FFR-deferred patients (24 [5.6%] vs 14 [2.8%], adjusted hazard ratio [HR] 2.07, 95% confidence interval [CI]: 1.07-4.03; p=0.03). In the subgroup of "any study lesion deferral", the MACE rate was 5.6% vs 3.6% (QFR vs FFR), adjusted HR 1.55, 95% CI: 0.88-2.73; p=0.13.

QFR-based deferral of coronary artery revascularisation resulted in a higher incidence of 1-year MACE as compared with FFR-based deferral.

Fractional flow reserve (FFR) derived from coronary angiography, referred to as ICA-FFR, is a less-invasive alternative for invasive FFR measurement based on computational fluid dynamics. Blood flow into side branches influences the accuracy of ICA-FFR. However, properly compensating for side branch flow in ICA-FFR analysis is challenging. In this study, we proposed a physiological side branch flow model to comprehensively compensate side branch flow for ICA-FFR analysis with no need for reconstructing side branch geometry.

the physiological side branch flow model employed a reduced-order model to calculate the pressure distribution in vessel segments. The main coronary artery (without side branches) was delineated and divided based on bifurcation nodes. The model compensates for flow to invisible side branches within each segment and flow to visible side branches at each bifurcation node. Lastly, ICA-FFR based on physiological side branch flow model (ICA-FFR) was calculated from a single angiographic view. Functional stenosis is defined by FFR 0.80.

Our study involved 223 vessels from 172 patients. Using invasive FFR as a reference, the Pearson correlation coefficient of ICA-FFR was 0.93. ICA-FFR showed a high AUC (AUC = 0.96) and accuracy (91.9) in predicting functional stenosis.

The proposed model accurately compensates for flow to side branches without their geometry in ICA-FFR analysis. ICA-FFR analysis exhibits high feasibility and diagnostic performance in identifying functional stenosis.

Risk stratification of patients with symptomatic nonobstructive coronary artery disease remains uncertain. Our study assessed the clinical value of single-vessel, multivessel, and 3-vessel computational angiography-derived fractional flow reserve (caFFR) measurement in patients with nonobstructive coronary artery disease.

We enrolled patients with ≤50% stenosis with a caFFR value ≥0.8 in all 3 coronary arteries on coronary angiography. The sum of caFFR values in the 3 vessels was computed for each patient. Patient stratification was based on the median value of the following criteria: single-vessel analysis, multivessel analysis, and 3-vessel analysis. The primary end point of this study was major adverse cardiac events at 5 years, defined as a composite of cardiac death, myocardial infarction, and ischemia-driven revascularization. A total of 490 patients were included. The 5-year major adverse cardiac event rates in single-vessel analysis were statistically insignificant between low- and high-caFFR groups (left anterior descending artery [P=0.163]; left circumflex artery [P=0.797]; right coronary artery [P=0.127]). In multivessel analysis, patients in the multiple-vessel low-caFFR group (with 2-3 vessels lower than median value of all coronary arteries) showed an increased risk of 5-year major adverse cardiac events compared with patients in the single-vessel low-caFFR group (0-1 vessel) (hazard ratio [HR], 2.648 [95% CI, 1.141-6.145]; P=0.023). In 3-vessel analysis, patients in the low 3-vessel caFFR group demonstrated a greater 5-year major adverse cardiac event risk than the high 3-vessel caFFR group (HR, 2.43 [95% CI, 1.087-5.433]; P=0.031).

We demonstrated that both multiple-vessel and 3-vessel caFFR measurements serve as valuable prognostic indicators for risk assessment in patients with nonobstructive coronary artery disease.

Continuous intravenous adenosine triphosphate (ATP) administration is the standard method for inducing maximal hyperemia in fractional flow reserve (FFR) measurements. Several cases have demonstrated fluctuations in the ratio of mean distal coronary pressure to mean arterial pressure (Pd/Pa) value during ATP infusion, which raised our suspicions of FFR value inaccuracy. This study aimed to investigate our hypothesis that Pd/Pa fluctuations may indicate inaccurate FFR measurements caused by insufficient hyperemia. We examined 57 consecutive patients with angiographically intermediate coronary lesions who underwent fractional flow reverse (FFR) measurements in our hospital between November 2016 and September 2018. Pd/Pa was measured after continuous ATP administration (150 μg/kg/min) via a peripheral forearm vein for 5 min (FFRA); and we analyzed the FFR value variation in the final 20 s of the 5 min, defining 'Fluctuation' as variation range > 0.03. Then, 2 mg of nicorandil was administered into the coronary artery during continued ATP infusion, and the Pd/Pa was remeasured (FFRA+N). Fluctuations were observed in 23 of 57 patients. The cases demonstrating discrepancies of > 0.05 between FFRA and FFRA+N were observed more frequently in the fluctuation group than in the non-fluctuation group (12/23 vs. 1/34; p < 0.0001). The discrepancy between FFRA and FFRA+N values was smaller in the non-fluctuation group (mean difference ± SD; -0.00026 ± 0.04636 vs. 0.02608 ± 0.1316). Pd/Pa fluctuation with continuous ATP administration could indicate inaccurate FFR measurements caused by incomplete hyperemia. Additional vasodilator administration may achieve further hyperemia when Pd/Pa fluctuations are observed.

Invasive fractional flow reserve (FFR) measurement is the gold standard method for coronary artery disease (CAD) diagnosis. FFR-CT exploits computational fluid dynamics (CFD) for non-invasive evaluation of FFR, simulating coronary flow in virtual geometries reconstructed from computed tomography (CT), but suffers from cost-intensive computing process and uncertainties in the definition of patient specific boundary conditions (BCs). In this work, we investigated the use of time-averaged steady BCs, compared to pulsatile to reduce the computational time and deployed a self-adjusting method for the tuning of BCs to patient-specific clinical data.

133 coronary arteries were reconstructed form CT images of patients suffering from CAD. For each vessel, invasive FFR was measured. After segmentation, the geometries were prepared for CFD simulation by clipping the outlets and discretizing into tetrahedral mesh. Steady BCs were defined in two steps: (i) rest BCs were extrapolated from clinical and image-derived data; (ii) hyperemic BCs were computed from resting conditions. Flow rate was iteratively adjusted during the simulation, until patient's aortic pressure was matched. Pulsatile BCs were defined exploiting the convergence values of steady BCs. After CFD simulation, lesion-specific hemodynamic indexes were computed and compared between group of patients for which surgery was indicated and not. The whole pipeline was implemented as a straightforward process, in which each single step is performed automatically.

Steady and pulsatile FFR-CT yielded a strong correlation (r = 0.988, p < 0.001) and correlated with invasive FFR (r = 0.797, p < 0.001). The per-point difference between the pressure and FFR-CT field predicted by the two methods was below 1 % and 2 %, respectively. Both approaches exhibited a good diagnostic performance: accuracy was 0.860 and 0.864, the AUC was 0.923 and 0.912, for steady and pulsatile case, respectively. The computational time required by steady BCs CFD was approximatively 30-folds lower than pulsatile case.

This work shows the feasibility of using steady BCs CFD for computing the FFR-CT in coronary arteries, as well as its computational and diagnostic performance within a fully automated pipeline.

Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital heart disease, potentially leading to myocardial ischemia and adverse cardiac events. As the sole presence of AAOCA does not always imply a revascularization, a detailed anatomical and functional analysis is crucial for clinical decision-making. Currently, invasive coronary angiography is the gold-standard method for a thorough hemodynamic assessment of AAOCA. However, due to its invasive nature, the development of noninvasive diagnostic alternatives is desired.

In the NARCO trial, patients with AAOCA will undergo coronary computed tomography angiography (CCTA) to assess anatomical high-risk features followed by a vessel-based (i.e. invasive measurement with fractional flow reserve and intravascular imaging under a dobutamine-volume challenge) and a myocardium-based (i.e. nuclear imaging) ischemia testing. Comparison of noninvasive and invasive imaging will be performed. Additionally, explorative analysis of post-processing advanced computational fluid dynamics (CFD) and 3D printing will be performed to unravel the pathophysiologic mechanism of myocardial ischemia in AAOCA.

Our primary aim is to define characteristics of anatomical high-risk features (using CCTA) to rule out noninvasively hemodynamically relevant anomalous vessels in AAOCA patients. The secondary aim is to investigate the underlying pathophysiology of AAOCA-related hemodynamic relevance using advanced techniques such as CFD and 3D printing.

The NARCO trial will help to optimize AAOCA patient selection for revascularization by improving risk stratification and ruling out hemodynamic relevance noninvasively and, therefore, preventing unnecessary downstream testing and/or costly interventions in patients with AAOCA.

Functional coronary angiography (FCA) is a novel modality for assessing the physiology of coronary lesions, going beyond anatomical visualization by traditional coronary angiography. FCA incorporates indices like fractional flow reserve (FFR) and instantaneous wave-free ratio (IFR), which utilize pressure measurements across coronary stenoses to evaluate hemodynamic impacts and to guide revascularization strategies. In this review, we present traditional and evolving modalities and uses of FCA. We will also evaluate the existing evidence and discuss the applicability of FCA in various clinical scenarios. Finally, we provide insight into emerging evidence, current challenges, and future directions in FCA.

The development of percutaneous coronary intervention (PCI) has been one of the greatest advances in cardiology and has changed clinical practice for patients with coronary artery disease (CAD). Despite continuous improvements in operators' experience, techniques, and the development of new-generation devices, significant challenges remain in improving the efficacy of PCI, including calcification, bifurcation, multivascular disease, stent restenosis, and stent thrombosis, among others. The present review aims to provide an overview of the current status of knowledge of endovascular revascularization in CAD, including relevant trials, therapeutic strategies, and new technologies addressing particular scenarios that can impact the prognosis of this vulnerable population.

Coronary heart disease is the leading cause of mortality in the United States, and data indicates that 805,000 Americans will face a new or recurrent myocardial infarction (MI) attack every year. Frailty, a conceptual syndrome categorized by a functional decline that occurs with aging, has been linked to adverse health outcomes in cardiovascular disease and all cardiac-related procedures in general. It is therefore reasonable to deliberate that more conservative medical therapy or medical management should be considered in the frail population when managing acute coronary syndrome. This course of action has, in fact, been documented in clinical practice. However, the recent Functional Assessment in Elderly MI Patients with Multivessel Disease trial, in which all subjects were 75 years of age or above, indicated that the more invasive complete revascularization approach may be favorable over incomplete or culprit-only revascularization in patients with acute MI. In this review, we will discuss coronary heart disease and review guidelines and procedures for culprit lesion identification, including electrocardiogram procedures, coronary angiography, intravascular ultrasound, fractional flow reserve, and instantaneous fractional flow reserve. We then discuss the concept of complete vs culprit-only/incomplete coronary revascularization and staging. Following this, we will delve into recent trials discussing complete vs culprit-only revascularization, emphasizing the insights gleaned from this latest trial within this special frailty cohort which warrants special consideration.

Fractional Flow Reserve (FFR) is used to characterize the functional significance of coronary artery stenoses. FFR is assessed under hyperemic conditions by invasive measurements of trans-stenotic pressure thanks to the insertion of a pressure guidewire across the coronary stenosis during catheterization. In order to overcome the potential risk related to the invasive procedure and to reduce the associated high costs, three-dimensional blood flow simulations that incorporate clinical imaging and patient-specific characteristics have been proposed.

Most CCTA-derived FFR models neglect the potential influence of the guidewire on computed flow and pressure. Here we aim to quantify the impact of taking into account the presence of the guidewire in model-based FFR prediction.

We adopt a CCTA-derived FFR model and perform simulations with and without the guidewire for 18 patients with suspected stable CAD.

Presented results show that the presence of the guidewire leads to a tendency to predict a lower FFR value. The FFR reduction is prominent in cases of severe stenoses, while the influence of the guidewire is less pronounced in cases of moderate stenoses.

From a clinical decision-making point of view, including of the pressure guidewire is potentially relevant only for intermediate stenosis cases.

Fractional flow reserve is widely used in coronary disease management, with a threshold of 0.80. However, similar thresholds are unclear in functional assessment of intracranial atherosclerotic stenosis (ICAS).

To investigate the potential threshold values in functional assessment of ICAS by studying the relation between pressure-derived indexes and perfusion parameters derived from arterial spin labeling (ASL).

Patients were consecutively screened between June 2019 and December 2020. The translesional gradient indices were measured by pressure guidewire under resting-state conditions and recorded as mean distal/proximal pressure ratios (Pd/Pa) and translesional pressure difference (Pa-Pd). Preoperative and postoperative cerebral blood flow (CBF) bilaterally and the relative cerebral blood flow ratio (rCBF) were measured and recorded by ASL imaging. Patients were defined as having reversible hemodynamic insufficiency only if the preoperative rCBF was <0.9 and the postoperative rCBF≥0.9. Preoperative and postoperative Pd/Pa or Pa-Pd values of those patients were used to calculate the threshold.

Twenty-five patients (19 men, 6 women) with a mean age of 56.7±9.4 years were analyzed. Seventeen patients (68%) had lesions at the M1 segment of the middle cerebral artery, eight patients (32%) had lesions in the intracranial internal carotid artery. In 14 of the 25 patients, the preoperative rCBF was <0.9 and the postoperative rCBF≥0.9. Cut-off values of Pd/Pa=0.81 and Pa-Pd=8 mm Hg were suggested to be associated with hemodynamic insufficiency.

In a highly selected subgroup with ICAS, cut-off values of translesional pressure gradients (Pd/Pa=0.81 or Pa-Pd=8 mm Hg) were preliminarily established, which may facilitate clinical decision-making in the management of ICAS.

The coronary artery constitutes a vital vascular system that sustains cardiac function, with its primary role being the conveyance of indispensable nutrients to the myocardial tissue. When coronary artery disease occurs, it will affect the blood supply of the heart and induce myocardial ischemia. Therefore, it is of great significance to numerically simulate the coronary artery and evaluate its blood supply capacity. In this article, the coronary artery lumped parameter model was derived based on the relationship between circuit system parameters and cardiovascular system parameters, and the blood supply capacity of the coronary artery in healthy and stenosis states was studied. The aortic root pressure calculated by the aortic valve fluid-structure interaction (AV FSI) simulator was employed as the inlet boundary condition. To emulate the physiological phenomenon of sudden pressure drops resulting from an abrupt reduction in blood vessel radius, a head loss model was connected at the coronary artery's entrance. For each coronary artery outlet, the symmetric structured tree model was appended to simulate the terminal impedance of the missing downstream coronary arteries. The particle swarm optimization (PSO) algorithm was used to optimize the blood flow viscous resistance, blood flow inertia, and vascular compliance of the coronary artery model. In the stenosis states, the relative flow and fractional flow reserve (FFR) calculated by numerical simulation corresponded to the published literature data. It was anticipated that the proposed model can be readily adapted for clinical application, serving as a valuable reference for diagnosing and treating patients.

Myocardial ischaemia results from insufficient coronary blood flow. Computed virtual fractional flow reserve (vFFR) allows quantification of proportional flow loss without the need for invasive pressure-wire testing. In the current study, we describe a novel, conductivity model of side branch flow, referred to as 'leak'. This leak model is a function of taper and local pressure, the latter of which may change radically when focal disease is present. This builds upon previous techniques, which either ignore side branch flow, or rely purely on anatomical factors. This study aimed to describe a new, conductivity model of side branch flow and compare this with established anatomical models.

The novel technique was used to quantify vFFR, distal absolute flow (Qd) and microvascular resistance (CMVR) in 325 idealised 1D models of coronary arteries, modelled from invasive clinical data. Outputs were compared to an established anatomical model of flow. The conductivity model correlated and agreed with the reference model for vFFR (r = 0.895, p < 0.0001; ＋0.02, 95% CI 0.00 to ＋ 0.22), Qd (r = 0.959, p < 0.0001; -5.2 mL/min, 95% CI -52.2 to ＋13.0) and CMVR (r = 0.624, p < 0.0001; ＋50 Woods Units, 95% CI -325 to ＋2549).

Agreement between the two techniques was closest for vFFR, with greater proportional differences seen for Qd and CMVR. The conductivity function assumes vessel taper was optimised for the healthy state and that CMVR was not affected by local disease. The latter may be addressed with further refinement of the technique or inferred from complementary image data. The conductivity technique may represent a refinement of current techniques for modelling coronary side-branch flow. Further work is needed to validate the technique against invasive clinical data.

A medical tool is a general instrument intended for use in the prevention, diagnosis, and treatment of diseases in humans or other animals. Nowadays, sensors are widely employed in medical tools to analyze or quantify disease-related parameters for the diagnosis and monitoring of patients' diseases. Recent explosive advancements in sensor technologies have extended the integration and application of sensors in medical tools by providing more versatile in vivo sensing capabilities. These unique sensing capabilities, especially for medical tools for surgery or medical treatment, are getting more attention owing to the rapid growth of minimally invasive surgery. In this review, recent advancements in sensor-integrated medical tools are presented, and their necessity, use, and examples are comprehensively introduced. Specifically, medical tools often utilized for medical surgery or treatment, for example, medical needles, catheters, robotic surgery, sutures, endoscopes, and tubes, are covered, and in-depth discussions about the working mechanism used for each sensor-integrated medical tool are provided.

Coronary computed tomography angiography (CCTA)-based fractional flow reserve (CT-FFR) allows for noninvasive determination of the functional severity of anatomic lesions in patients with coronary artery disease. The aim of this study was to intra-individually compare CT-FFR between photon-counting detector (PCD) and conventional energy-integrating detector (EID) CT systems.

In this single-center prospective study, subjects who underwent clinically indicated CCTA on an EID-CT system were recruited for a research CCTA on PCD-CT within 30 days. Image reconstruction settings were matched as closely as possible between EID-CT (Bv36 kernel, iterative reconstruction strength level 3, slice thickness 0.5 mm) and PCD-CT (Bv36 kernel, quantum iterative reconstruction level 3, virtual monoenergetic level 55 keV, slice thickness 0.6 mm). CT-FFR was measured semi-automatically using a prototype on-site machine learning algorithm by two readers. CT-FFR analysis was performed per-patient and per-vessel, and a CT-FFR ≤ 0.75 was considered hemodynamically significant.

A total of 22 patients (63.3 ± 9.2 years; 7 women) were included. Median time between EID-CT and PCD-CT was 5.5 days. Comparison of CT-FFR values showed no significant difference and strong agreement between EID-CT and PCD-CT in the per-vessel analysis (0.88 [0.74-0.94] vs. 0.87 [0.76-0.93], P = 0.096, mean bias 0.02, limits of agreement [LoA] -0.14/0.19, r = 0.83, ICC = 0.92), and in the per-patient analysis (0.81 [0.60-0.86] vs. 0.76 [0.64-0.86], P = 0.768, mean bias 0.02, LoA -0.15/0.19, r = 0.90, ICC = 0.93). All included patients were classified into the same category (CT-FFR > 0.75 vs ≤0.75) with both CT systems.

CT-FFR evaluation is feasible with PCD-CT and it shows a strong agreement with EID-CT-based evaluation when images are similarly reconstructed.

Modern coronary intervention requires integration of angiographic, physiologic, and intravascular imaging. This article describes the use and techniques needed to understand coronary physiology pullback data and how use it to make revascularization decisions. The article describes instantaneous wave-free ratio, fractional flow reserve, and the data that support their use and how they differ when used in tandem disease. Common practical mistakes and errors are discussed together with a brief review of the limited published research data.

Despite the now routine integration of invasive physiologic systems into coronary catheter laboratories worldwide, it remains critical that all operators maintain a sound understanding of the fundamental physiologic basis for coronary pressure assessment. More specifically, performing operators should be well informed regarding the basis for hyperemic (ie, fractional flow reserve) and nonhyperemic (ie, instantaneous wave-free ratio and other nonhyperemic pressure ratio) coronary pressure assessment. In this article, we provide readers a comprehensive history charting the inception, development, and validation of hyperemic and nonhyperemic coronary pressure assessment.

This study aimed to design an end-to-end deep learning model for estimating the value of fractional flow reserve (FFR) using angiography images to classify left anterior descending (LAD) branch angiography images with average stenosis between 50 and 70% into two categories: FFR > 80 and FFR ≤ 80. In this study 3625 images were extracted from 41 patients' angiography films. Nine pre-trained convolutional neural networks (CNN), including DenseNet121, InceptionResNetV2, VGG16, VGG19, ResNet50V2, Xception, MobileNetV3Large, DenseNet201, and DenseNet169, were used to extract the features of images. DenseNet169 indicated higher performance compared to other networks. AUC, Accuracy, Sensitivity, Specificity, Precision, and F1-score of the proposed DenseNet169 network were 0.81, 0.81, 0.86, 0.75, 0.82, and 0.84, respectively. The deep learning-based method proposed in this study can non-invasively and consistently estimate FFR from angiographic images, offering significant clinical potential for diagnosing and treating coronary artery disease by combining anatomical and physiological parameters.

Grading of carotid stenosis is routinely performed with non-invasive techniques, such as carotid ultrasound (CUS) and computerized tomography angiography (CTA), which have limitations in grading definition. Moreover, the actual hemodynamic impact of a stenosis remains poorly defined. Preliminary studies explored the application of the resting full-cycle ratio (RFR), measured with pressure wire (PW), but the correlation between RFR and morphological/hemodynamic parameters is still undefined. This study aims to test the correlation between RFR and CUS-CTA-DSA based degree of stenosis, to define the suitability of RFR as carotid stenosis index.

We included patients with symptomatic carotid stenosis receiving carotid artery stenting (CAS), between November 2022 and May 2023. We performed CUS and PW measurements before and after stenting, at four different sites (trans-lesion, distal cervical, petrous and supraclinoid internal carotid artery [ICA] segments). We compared CUS and PW parameters by Pearson's or Spearman test for continuous variables.

Among 15 patients included the mean stenosis degree was 81.3%. Trans-lesion RFR was significantly higher than other sites (0.72 ± 0.2 trans-lesion vs. 0.69 ± 0.18 distal cervical ICA vs. 0.66 ± 0.2 petrous ICA vs. 0.6 ± 0.2 intracranial ICA, p < 0.05). All RFR values significantly increased after treatment; the highest relative increase was registered at stenosis site (0.72 ± 0.2 pre-stent vs. 1.01 ± 0.1 post-stent, p < 0.01). Trans-lesion RFR was significantly associated with the CTA and DSA stenosis degree and CUS measurements.

Pressure wire in carotid artery stenosis seems safe and suitable. Resting full-cycle ratio has a significant correlation with CUS values and stenosis degree and might be used as carotid stenosis index during CAS.

Coronary angiography has a limited ability to predict the functional significance of intermediate coronary lesions. Hence, physiological assessment of coronary lesions, via fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR), has been introduced to determine their functional significance. An accumulating body of evidence has consolidated the role of physiology-guided revascularization, particularly among patients with stable ischemic heart disease. The use of FFR or iFR to guide decision-making in patients with stable ischemic heart disease and intermediate coronary lesions received a class I recommendation from major societal guidelines. Nevertheless, the role of coronary physiology testing is less clear among certain patients' groups, including patients with serial coronary lesions, acute coronary syndromes, aortic stenosis, heart failure, as well as post-percutaneous coronary interventions. In this review, we aimed to discuss the utility and clinical evidence of coronary physiology (mainly FFR and iFR), with emphasis on those specific patient groups.

Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital coronary anomaly with the potential to cause myocardial ischemia and adverse cardiac events. The presence of AAOCA anatomy itself does not necessarily implicate a need for revascularization. Therefore, the purpose of this review is to assess how noninvasive comprehensive anatomic- and physiologic evaluation may guide patient management.

The assessment of AAOCA includes an accurate description of the anomalous origin/vessel course including anatomical high-risk features such as a slit-like ostium, proximal narrowing, elliptic vessel shape, acute take-off angle, intramural course, and possible concomitant coronary atherosclerosis and hemodynamics. Various cardiac imaging modalities offer unique advantages and capabilities in visualizing these anatomical and functional aspects of AAOCA. This review explored the role of noninvasive multimodality imaging in the characterization of AAOCA by highlighting the strengths, limitations, and potential applications of the current different cardiac imaging methods, with a focus on the pathophysiology of myocardial ischemia and stress testing protocols.

Graft occlusion after coronary artery bypass grafting (CABG) has been associated with competitive flow of native coronary arteries.

To assess with coronary computed tomography angiography (CCTA) graft occlusion and coronary artery disease (CAD) progression of native vessels after CABG and their relationship with angiography-derived vessel fractional flow reserve (vFFR) performed before surgery.

Between 2006 and 2018, serial vFFR analyses were obtained before CABG in each major native coronary vessel from two institutions. All patients underwent follow-up CCTA.

In 171 consecutive patients, serial preoperative angiograms were suitable for vFFR analysis of 298 grafted and 59 nongrafted vessels. Median time between CABG and CCTA was 2.1 years. Preoperative vFFR was assessed in 131 left anterior descending artery (LAD), 132 left circumflex artery (LCX) and 94 right coronary aretry (RCA) and was less than 0.80 in 255 of 298 bypassed vessels. Graft occlusion was observed at CCTA in 28 of 298 grafts. The median preoperative vFFR value of native coronaries was higher in occluded compared with patent grafts (0.75 vs. 0.60, P < 0.001) and was associated with graft. The best vFFR cut-off to predict graft occlusion was 0.67. Progression of CAD was higher in grafted than in nongrafted vessels (89.6 vs. 47.5%, P < 0.001). Pre-CABG vFFR predicted disease progression of grafted native vessels (AUC = 0.83).

Preoperative vFFR derived from invasive coronary angiography was able to predict graft occlusion and CAD progression of grafted coronary arteries.

Coronary angiography-derived fractional flow reserve (caFFR) is a novel computational flow dynamics (CFD)-derived assessment of coronary vessel flow with good diagnostic performance. Herein, we performed a retrospective study to evaluate the reproducibility of caFFR findings between observers and investigate the diagnostic performance of caFFR for coronary stenosis defined as FFR ≤0.80, especially in the grey zone (0.75≤caFFR ≤0.80).

A total of 150 patients (167 coronary vessels) underwent caFFR (with FlashAngio used for calculation of flow variables) and subsequent invasive fractional flow reserve (FFR) measurements. Outcomes, including reproducibility, were compared for vessels in and outside the grey zone.

The correlation of caFFR findings was good between the two laboratories (r = 0.723, p<0.001). The AUC of ROC were both high for caFFR-CoreLab1 and caFFR-CoreLab2 (0.975 and 0.883). The diagnostic accuracy, sensitivity, specificity, and negative and positive predictive values were not significantly different between the two laboratories (p>0.05). caFFR had a strong correlation with measures to FFR (r=0.911, p<0.001). There was no systematic difference between caFFR and FFR on Bland-Altman analysis in and outside the grey zone. There was no difference in diagnostic accuracy between the grey and non-grey zones in the prediction of FFR ≤0.80 (p=0.09).

The inter-observer reproducibility for caFFR was high, and the diagnostic accuracy of caFFR was good compared to that of FFR.

During fractional flow reserve (FFR) measurements, distal coronary pressure (Pd) can be influenced by hydrostatic pressure changes resulting from the height difference (HD) between the coronary ostium and the location of the distal pressure sensor.

We investigated the effect of aortocoronary HD on the FFR measurements in each coronary artery.

In this retrospective cohort study, we analyzed 257 patients who underwent FFR measurements and coronary computed tomography (CCTA) within a year. Using CCTA, we measured HD as the vertical distance between the coronary ostium and a matched point of the distal coronary pressure sensor identified on coronary angiography.

The location of the Pd sensor was higher than the coronary ostium in the left anterior descending artery (LAD) (-4.64 ± 1.15 cm) and lower than the coronary ostium in the left circumflex artery (LCX) (2.54 ± 1.05 cm) and right coronary artery (RCA) (2.03 ± 1.28 cm). The corrected FFR values by HD were higher in the LAD (0.78 ± 0.09 to 0.82 ± 0.09, P<0.01) and lower in the LCX and RCA than the original FFR values (0.87 ± 0.07 to 0.85 ± 0.08, P<0.01; 0.87 ± 0.10 to 0.86 ± 0.10, P<0.01, respectively). Using an FFR cut-off value of 0.8, the concordance rates between the FFR and corrected FFR values were 77.8%, 95.2%, and 100% in the LAD, LCX, and RCA, respectively.

HD between the coronary ostium and the distal coronary pressure sensor may affect FFR measurements and FFR-guided treatment decisions for coronary artery disease.

Epicardial coronary stenosis may lead to myocardial ischaemia, and the resulting obstructive coronary artery disease is one of the leading causes of death. CT-derived fractional flow reserve (CT-FFR) has been clinically shown to be an effective method for the noninvasive assessment of coronary artery stenosis. However, this method has the problem that the measurement result is affected by the selected measurement position.

This study was to obtain a novel flow-based approach to coronary CTFFR (CTQFFR), which was not affected by the measurement location.

This study established healthy-assumed coronary arteries based on narrowed coronary arteries. Based on the assumption that the microvascular resistance remains unchanged in the short term after coronary stenosis treatment, the blood flow in the stenotic coronary artery and the healthy-assumed coronary artery was obtained by numerical simulation, and the CTQFFR based on the blood flow ratio was calculated. The functional relationship between CTQFFR and FFR was fitted by the results of 20 cases.

In this study, the functional relationship between CTQFFR and FFR was fitted by a quadratic curve, and the variance was 0.8744; the functional relationship between CTQFFR and pressure-based approach to coronary CTFFR (CTPFFR) was fitted by a primary curve, and the variance was 0.9971. There was coronary artery growth in all 20 cases. Preliminary validation results using 10 cases showed 100% accuracy in determining whether coronary artery stenosis required for clinical intervention. The relative error of the coefficient with the results proposed in a previous study was 0.316%.

This study proposes a new method for calculating coronary CTFFR, namely, coronary CTQFFR, which is the flow ratio between stenotic coronary and healthy-assumed coronary. This method solves the problem that the downstream CTFFR of coronary stenosis is related to the selected location, which effectively improves the CTFFR at the critical value (CTFFR= 0.8) near reliability. Preliminary research results show that the method obtained in this study has a high accuracy for determining whether there is significant coronary stenosis. However, large multi-centre validation for the feasibility of this method was necessary in our future work.

Despite considerable improvement in diagnostic modalities and therapeutic options over the last few decades, the global burden of ischemic heart disease is steadily rising, remaining a major cause of death worldwide. Thus, new strategies are needed to lessen cardiovascular events. Researchers in different areas such as biotechnology and tissue engineering have developed novel therapeutic strategies such as stem cells, nanotechnology, and robotic surgery, among others (3D printing and drugs). In addition, advances in bioengineering have led to the emergence of new diagnostic and prognostic techniques, such as quantitative flow ratio (QFR), and biomarkers for atherosclerosis. In this review, we explore novel diagnostic invasive and noninvasive modalities that allow a more detailed characterization of coronary disease. We delve into new technological revascularization procedures and pharmacological agents that target several residual cardiovascular risks, including inflammatory, thrombotic, and metabolic pathways.

Epicardial adipose tissue (EAT) is directly related to coronary artery disease (CAD), but little is known about its role in hemodynamically significant CAD. Therefore, our goal is to explore the impact of EAT volume on hemodynamically significant CAD.

Patients who underwent coronary computed tomography angiography (CCTA) and received coronary angiography within 30 days were retrospectively included. Measurements of EAT volume and coronary artery calcium score (CACs) were performed on a semi-automatic software based on CCTA images, while quantitative flow ratio (QFR) was automatically calculated by the AngioPlus system according to coronary angiographic images.

This study included 277 patients, 112 of whom had hemodynamically significant CAD and showed higher EAT volume. In multivariate analysis, EAT volume was independently and positively correlated with hemodynamically significant CAD [per standard deviation (SD) cm3; odds ratio (OR), 2.78; 95% confidence interval (CI), 1.86-4.15; P < 0.001], but negatively associated with QFRmin (per SD cm3; β coefficient, -0.068; 95% CI, -0.109 to -0.027; P = 0.001) after adjustment for traditional risk factors and CACs. Receiver operating characteristics curve analysis demonstrated a significant improvement in predictive value for hemodynamically significant CAD with the addition of EAT volume to obstructive CAD alone (area under the curve, 0.950 vs. 0.891; P < 0.001).

In this study, we found that EAT volume correlated substantially and positively with the existence and severity of hemodynamically significant CAD in Chinese patients with known or suspected CAD, which was independent of traditional risk factors and CACs. In combination with obstructive CAD, EAT volume significantly improved diagnostic performance for hemodynamically significant CAD, suggesting that EAT could be a reliable noninvasive indicator of hemodynamically significant CAD.

The landscape of interventional cardiology is ever evolving. Contemporary practice has shifted from a stenosis-centred approach to the total characterisation of both the epicardial and microcirculatory vessels. Microcirculatory dysfunction plays an important role in the pathophysiology of acute and chronic coronary syndromes, and characterisation of the microcirculation has important clinical consequences. Accordingly, the invasive diagnosis of microcirculatory dysfunction is becoming a key feature of the interventional cardiologist's toolkit. This review focuses on the methodology underpinning the invasive diagnosis of microvascular dysfunction and highlights the indices that have arisen from these methodologies.

Ischaemic heart disease results from insufficient coronary blood flow. Direct measurement of absolute flow (mL/min) is feasible, but has not entered routine clinical practice in most catheterization laboratories. Interventional cardiologists, therefore, rely on surrogate markers of flow. Recently, we described a computational fluid dynamics (CFD) method for predicting flow that differentiates inlet, side branch, and outlet flows during angiography. In the current study, we evaluate a new method that regionalizes flow along the length of the artery.

Three-dimensional coronary anatomy was reconstructed from angiograms from 20 patients with chronic coronary syndrome. All flows were computed using CFD by applying the pressure gradient to the reconstructed geometry. Side branch flow was modelled as a porous wall boundary. Side branch flow magnitude was based on morphometric scaling laws with two models: a homogeneous model with flow loss along the entire arterial length; and a regionalized model with flow proportional to local taper. Flow results were validated against invasive measurements of flow by continuous infusion thermodilution (Coroventis™, Abbott). Both methods quantified flow relative to the invasive measures: homogeneous (r 0.47, P 0.006; zero bias; 95% CI -168 to +168 mL/min); regionalized method (r 0.43, P 0.013; zero bias; 95% CI -175 to +175 mL/min).

During angiography and pressure wire assessment, coronary flow can now be regionalized and differentiated at the inlet, outlet, and side branches. The effect of epicardial disease on agreement suggests the model may be best targeted at cases with a stenosis close to side branches.

Microvascular resistance reserve (MRR) is a new index to assess coronary microvascular (dys)function, which can be easily measured invasively using continuous thermodilution. In contrast to coronary flow reserve (CFR), MRR is independent of epicardial coronary disease and hemodynamic variations. Its measurement is accurate, reproducible, and operator independent.

The aim of this study was to establish the range of normal values for MRR and to determine an optimal cutoff point.

In this exploratory study in 214 patients with angina and no obstructive coronary artery disease, after excluding significant epicardial disease, all physiological parameters, such as fractional flow reserve, index of microvascular resistance, CFR, absolute blood flow, absolute microvascular resistance, and MRR, were measured. On the basis of concordant positive or concordant negative results of index of microvascular resistance and CFR, subgroups of patients were defined with high probability of either normal (n = 122) or abnormal (n = 24) microcirculatory function, and MRR was studied in these groups.