Isolated double-chambered right ventricle in an adult: A case report

Abstract

BACKGROUND

Double-chambered right ventricle (DCRV) is a rare congenital heart defect defined by an abnormal muscular band creating high-pressure proximal and low-pressure distal chambers. This case report adds to the medical literature by highlighting the importance of early recognition and diagnosis of DCRV to prevent right ventricular failure.

CASE SUMMARY

A 26-year-old female was diagnosed with DCRV after presenting with exertional dyspnea and easy fatigue. Following close clinical monitoring, surgical resection of the right ventricular muscle bundle resulted in significant symptomatic improvement.

CONCLUSION

Timely identification of DCRV is critical to prevent complications and progressive right ventricular failure.

Key Words: Double-chambered right ventricle; Muscle bundle; Congenital heart disease; Right ventricular outflow tract obstruction; Case report

Core Tip: Early detection of double-chambered right ventricle (DCRV) is essential for optimal patient outcomes. Close monitoring and tailored interventions are necessary to address the complexities associated with DCRV and prevent potential complications, particularly the development of right ventricular failure. A multidisciplinary approach involving cardiologists, cardiac surgeons, and other specialists is key to providing comprehensive care for patients with DCRV.

INTRODUCTION

Double-chambered right ventricle (DCRV) is a rare congenital heart defect, accounting for only about 0.5%-2% of all cases. It occurs when hypertrophied muscle bundles divide the right ventricle into high- and low-pressure chambers, which is frequently associated with a ventricular septal defect[1]. It is also associated with conditions such as pulmonary valve stenosis or subaortic stenosis. DCRV primarily occurs in children, with isolated adult cases being rare[2]. DCRV was first described in 1867 as a constriction of the proximal infundibulum[3]. The condition itself was first treated surgically in 1962 by Lucas et al[4] through a partial ventriculotomy[5].

Adult presentation of this congenital heart defect can be under-recognized due to its varied clinical presentation and absence of other associated congenital cardiac defects[6,7]; although, trans-thoracic echocardiogram is a reliable method for establishment of the diagnosis of DCRV[8,9]. A recent cohort study by Amano et al[9] found that, with appropriate surgical management, DCRV carries an excellent long-term prognosis.

CASE PRESENTATION

Chief complaints

A 26-year-old woman presented with a 6-month history of progressive exertional dyspnea, fatigability, and chest pain after physical exertion.

History of present illness

The patient’s symptoms were mainly exertional, including progressive shortness of breath, fatigue, and chest pain triggered by physical activity. Her marked limitation in physical activity was consistent with New York Heart Association class III heart failure. She had no history of palpitation or syncope, and reported no additional systemic symptoms.

History of past illness

The patient reported no significant past medical history.

Personal and family history

The patient reported no significant personal and family history.

Physical examination

Cardiovascular examination revealed normal first and second heart sounds accompanied by a loud, harsh holosystolic murmur at the left sternal border, with palpable thrill.

Laboratory examinations

Laboratory examinations were non-contributory.

Imaging examinations

Electrocardiogram showed sinus rhythm at 60 bpm and right-axis deviation, as well as signs of right ventricular overload (Figure 1). Trans-thoracic echocardiography revealed a DCRV due to a prominent right ventricular muscle bundle creating a tunnel-like obstruction [Figure 2A-C and Video, Video trans-thoracic echocardiogram (modified parasternal short-axis view) using combined two-dimensional and color Doppler imaging, demonstrating a double-chambered right ventricle with a tunnel-like obstruction. Color-Doppler demonstrating turbulence of flow across the right ventricular muscle bundle. Flattening of the ventricular septum at mid-systole indicates a hypertensive proximal right chamber]. The proximal chamber was hypertensive, with an estimated peak gradient (PG) across the orifice of 132 mmHg, indicating severe right ventricular outflow tract (RVOT) obstruction (Figure 2D). Moderate tricuspid regurgitation (TR) was noted with an estimated PG of 65 mmHg (Figure 2E). There was no pressure gradient between the distal right ventricle chamber and the main pulmonary artery; the interventricular septum was intact, and the left ventricular function was normal.

Figure 1  12-lead electrocardiogram showing sinus rhythm at 60 bpm with right-axis deviation, and T wave inversion in the right pericardial and inferior leads.

Figure 2 Echocardiographic features of double-chambered right ventricle with right ventricular obstruction and Doppler assessment. A: Trans-thoracic echocardiogram, parasternal modified short-axis view (at mitral valve level) demonstrating a double-chambered right ventricle with a tunnel-like obstruction (arrow) due to a prominent right ventricular muscle bundle and right ventricular hypertrophy. The arrow highlights a right ventricular muscle bundle that forms the tunnel-like obstruction; B: Trans-thoracic echocardiogram, parasternal modified short-axis view demonstrating a double-chambered right ventricle with a tunnel-like obstruction (arrow) due to a prominent right ventricular muscle bundle. The arrow highlights a right ventricular muscle bundle that forms the tunnel-like obstruction; C: Color-Doppler demonstrating turbulence of flow across the right ventricular muscle bundle; D: Continuous-wave Doppler across the area of obstruction (intra-cavity), with an estimated peak gradient of 132 mmHg; E: Continuous-wave Doppler across the tricuspid valve, with an estimated peak gradient of 65 mmHg. dRV: Distal right ventricular chamber; LV: Left ventricular cavity; pRV: Proximal right ventricular chamber.

Intra-operative transesophageal echocardiography showed a significant reduction in RVOT obstruction, indicated by decreased TR and a reduced RVOT gradient with an estimated PG of 20 mmHg. Only mild TR with an estimated PG of 29 mmHg remained (Figure 3).

Figure 3 Intra-operative trans-esophageal echocardiography showing resolution of right ventricular outflow tract obstruction and reduced tricuspid regurgitation gradient. A: Intra-operative trans-esophageal echocardiography (trans-esophageal echocardiography; mid-esophageal, 0°) revealed a significant decrease in the tricuspid regurgitation gradient, decreasing from 65 mmHg to 29 mmHg; B: Two-dimensional trans-gastric trans-esophageal echocardiography view at 0° demonstrating alleviation of right ventricular outflow tract obstruction.

FINAL DIAGNOSIS

DCRV causing severe RVOT obstruction.

TREATMENT

The patient underwent surgical resection of the obstructing right ventricular muscle bundle via the right atriotomy approach. Intraoperatively, an anomalous fibrotic and hypertrophied muscle was found at the infundibulum opening (infundibular ostium); no other cardiac lesions were identified.

OUTCOME AND FOLLOW-UP

The immediate post-operative course was smooth, with no experience of surgical complications. Echocardiogram imaging demonstrated significant reduction in RVOT obstruction and TR. Follow-up echocardiography at the first clinic visit and at 6 months post-operation confirmed sustained hemodynamic improvement (Figure 4). The patient reported resolution of her symptoms, with no limitations in her daily activities.

Figure 4 Post-operative trans-thoracic echocardiography showing resolution of right ventricular outflow tract obstruction and marked reduction in pressure gradient. A: Post-operative trans-thoracic echocardiography, parasternal short-axis view demonstrating laminar flow across the right ventricular outflow tract; B: Continuous-wave Doppler across the right ventricular outflow tract showing a reduction in post-operative right ventricular outflow tract gradient from 132 mmHg to almost 20 mmHg.

DISCUSSION

DCRV is a rare congenital heart defect characterized by division of the right ventricle into two chambers by abnormal muscular bundles. It is frequently associated with other heart anomalies, of which VSD is most common. Other potential associated defects include pulmonary valve stenosis, atrial septal defect, aortic valve regurgitation, persistent left superior vena cava, ruptured sinus of Valsalva aneurysm, tetralogy of Fallot, transposition of the great arteries, and Ebstein’s anomaly. Therefore, a meticulously performed trans-thoracic echocardiogram is often sufficient to establish the diagnosis of DCRV. However, alternative causes of RVOT obstruction should be carefully excluded through comprehensive evaluation of the pulmonary valve and subvalvular area. In addition, detailed assessment of the interventricular septum should be carried out to identify associated VSD and to exclude anterior deviation of the outlet septum, which may suggest more complex congenital cardiac abnormalities such as tetralogy of Fallot. It is uncommon for DCRV to occur as an isolated finding, completely independent of other associated cardiac anomalies[6]. However, a recent case report highlighted the need to consider isolated DCRV in adults, noting that while rare, it may be under-recognized due to its varied presentation[7].

DCRV is characterized by progressive right ventricular obstruction caused by hypertrophied muscle bundles. This process, often linked to a VSD, results from a combination of muscle hypertrophy and endocardial fibrosis. Patients often present with a range of symptoms, including fatigue, dyspnea, syncope, or palpitations from transient arrhythmias. Primary treatment is surgical, generally involving resection of the anomalous muscular bundle and correction of associated cardiac defects. The timing of surgery is determined by the severity of the obstruction and the presence of coexisting anomalies. Observation is appropriate in the absence of significant lesions, provided the intracavitary systolic gradient does not exceed 40 mmHg and the obstruction remains non-progressive[1,2,8,9].

Several classification systems have been proposed for DCRV; however, a simpler classification was described by Galiuto et al[10] which categorizes DCRV into two distinct types based on the mechanism of intracavitary obstruction. Type 1 is characterized by the presence of an anomalous muscular bundle traversing the right ventricle cavity and producing an obstruction, whereas type 2 results from marked hypertrophy of the parietal and septal muscle components without a discrete anomalous bundle. Based on the echocardiographic and intraoperative findings, our case was deemed consistent with type 1 DCRV (as the obstruction was caused by an anomalous muscular bundle within the right ventricle).

In previous reports, most documented cases of DCRV were diagnosed in adolescence or early adulthood, and occasionally accompanied by other congenital defects. Examples include Garg et al[2], who described an adult patient with isolated DCRV in 2020; Park et al[6], who detailed an asymptomatic young adult in 2011; and Chellappan et al[11], who reported an intact septum in a 13-year-old in 2016. Conversely, our case is distinct due to the patient’s age at diagnosis and the complete absence of associated cardiac defects.

In the cohort reported on by Amano et al[9], patients who had undergone surgical correction were followed up for over a decade. The absence of deaths and reoperations during this period highlighted the long-term durability of the procedure. Echocardiogram-obtained data provided evidence of no recurrence of right ventricular obstruction, with significantly reduced systolic pressures maintained immediately after surgery and throughout the follow-up period. These findings underscore that surgical intervention not only alleviates the hemodynamic burden caused by the obstruction but also provides sustained functional improvement with no or minimal complication over decades of follow up[9].

CONCLUSION

DCRV is a rare congenital anomaly with variable clinical presentations especially in adults, often leading to misdiagnoses. Our case illustrates that DCRV can present as an isolated pathology with no recognizable associated cardiac defects. Prompt identification and surgical repair of this anomaly generally lead to an excellent long-term clinical outcome.