Role of Echocardiograghy in Treating a Case of Double Chamber Right Ventricle with Delayed Presentation.

The clinical diagnosis of double chamber right ventricle (DCRV) is not straightforward. Clinical history, clinical examination, 12-lead electrocardiogram, chest X-ray, and Echocardiography (echo) contribute to morphological diagnosis. Cardiac catheterization is essential for hemodynamic evaluation. A thorough presurgical workup helps the cardiac surgeon to choose the appropriate surgical approach and timing of surgery in an individual case. We present a case of a DCRV who presented to us in the fifth decade of life. Echo confirmed the morphological diagnosis and cardiac catheterization complemented the exact pull back gradient across the obstruction in the right ventricle. This patient was suggested muscle bundle resection and ventricular septal defect closure using right atrial approach.

Introduction

Double-chambered right ventricle (DCRV) is a rare clinical diagnosis at the age of the fifth decade of life.[1] The male:female ratio at birth is 2:1. An anomalous muscle bundle separates the right ventricle (RV) into a higher proximal pressure chamber (inlet and apex together), and a dilated low distal pressure chamber (infundibular portion of RV just below the pulmonary valve). A small subaortic ventricular septal defect (VSD) is seen in >90% of cases, communicating left ventricular (LV) outflow tract and distal chamber. The muscle bundle grows in size over time though it is identifiable in the early part of childhood. Similar to ambiguity of clinical diagnosis, there are several hypotheses which explain the development of the hypertrophied obstructive bundle in the subinfundibular portion of RV. Maron et al.[2] suggested that increased blood flow VSD would stimulate localized muscular hypertrophy based on microscopic observations of muscular cells resected from the supraventricular crest. Wong et al.[3] proposed superior displacement of the moderator band (known as the septomarginal trabecula) caused the obstruction based on echocardiographic (echo) measurements. Alva et al.[4] described the anomalous muscle bundle as the accentuated septoparietal trabecula. The degree of obstruction increases with age up to 4-fold over a period of 6 years[5] which explains the patients with late presentation have features of significant obstruction with right heart failure. All symptomatic patients and all asymptomatic patients with gradient more 40 mmHg should be operated.[1] A detail evaluation before surgery is to define the exact level of obstruction, invasive gradient, VSD, degree of left to right shunt, and any other associated defect which help the operating surgeon to choose an appropriate surgical approach.[6]

Case Report

A 48-year-old man presented with gradual worsening of dyspnea on exertion for the last 15 years. He was married having 3 children. He used to smoke and drink. He was manual labor. The recent onset of giddiness on exertion brought him to hospital. He was in sinus rhythm with normal blood pressure. Room air SPO2 was 94%. His neck veins were distended with the regular beeping of prominent a-wave just above the clavicle. There was no cyanosis, clubbing or dysmorphic feature. Abdominal palpation showed soft and tender enlargement of the liver. Cardiac palpation revealed no RV heave. Auscultation revealed a pansystolic murmur of Grade-3/6 along the left sternal border which was loudest at the 4th left intercostal space without selective propagation to cardiac apex or left shoulder. Twelve-lead electrocardiogram (ECG) revealed RV hypertrophy and right atrial enlargement, but no tall T in the right sided V3 (RV3) lead [Figure 1a and b]. Chest X-ray revealed normal situs, RV apex, dilated right atrium (RA) and there was no oligemia despite dilated infundibulum of RV [Figure 2]. Transthoracic echo showed RV hypertrophy, severe obstruction of the outflow tract (RV outflow tract) and severe high-pressure tricuspid regurgitation (TR). The main pulmonary artery (MPA) was 2.8 cm in diameter. There was no evidence of pulmonary valvular stenosis or incompetence [Video 1]. The LV was of normal size and function. The echo gradient was not reliable because echo beam was not aligning with the jet emerging from the site of obstruction. The gradient was also confounded by severe TR. Although the pathological diagnosis was conclusive by echo, cardiac catheterization was done to find the gradient across the subinfundibular stenosis. Invasive gradient was 175 mmHg. RV angiogram in swallow left anterior oblique with cranial angulation (cranial) view was consistent with echo [Videos 2–5]. The coronary angiogram showed mild coronary arterial disease and nondominant left circumflex coronary artery. Hemodynamic study showed the pressures measured in mmHg: RA-7; RV-190; RV end diastolic pressure-10; distal chamber-20; pulmonary artery pressure-15/2/7; pulmonary capillary wedge pressure-4; femoral artery (FA)-150/80/108; LV-140/0–10 and saturation in percent: Inferior vena cava-80; RA-59; superior vena cava-53; pulmonary artery-59; FA-94.

Figure 1

Twelve-lead electrocardiogram suggests right ventricular hypertrophy; right atrial enlargement and absence of early transition (a) and absence of tall T-wave in right ventricular 3 lead (b).

Figure 2

Chest X-ray posterior anterior projection (view) shows right ventricular type of apex (1), right atrial enlargement; full of pulmonary bay (2) despite significant right ventricular outflow tract obstruction and oligemic lung fields (3).

This patient underwent successful muscle bundle resection and VSD closure through right atrial approach. Postoperative follow-up was echo based and uneventful.

Discussion

When evaluating an adult with symptoms and signs of primary right heart failure in the elderly people, cardiologists should make an effort to consider DCRV as one of the differential diagnosis though it is rare in the later age of life.[1] The most common symptom is dyspnea on exertion due to low cardiac output in adult in the contrary to accidental detection or asymptomatic presentation in the usual age of presentation, i.e. 11–20 years of age.[78] Neither inheritance pattern nor any risk factors have been described earlier as a causal association in this condition. A palpable pulsation in left 3rd and 4rth intercostal space which corresponds to dilated infundibulum, normal split of the second heart sound with normal respiratory variation, a normal intensity of pulmonic component, a diffuse thrill over the precordium and a holosystolic murmur with maximum intensity at left lower sternal border are suggestive of DCRV. However, at this level, our case had no parasternal lift and no thrill. The possible explanation for these unusual findings is the associated severe TR valve and VSD in the presence of RV dysfunction. Systolic murmur in Ebstein's anomaly and pink tetralogy of Fallot (TOF) may be considered in the preferred differential diagnosis in such situation. The typical fullness of pulmonary bay due to infundibular dilatation was well delineated in our case which was well seen in the chest X-ray. Twelve-lead ECG may show upright T-wave in RV3 lead in 30%–40% cases due to RV hypertrophy[9] but was not seen in our case. Sometimes, subcostal echo window is preferable to transthoracic windows for proper visualization of the site of obstruction in DCRV. Echo is helpful for anatomical diagnosis in 70%–80% of cases.[10] However, the hemodynamic significance of gradient by cardiac catheterization really helps in deciding timing of the surgery in younger age. In this index case, significantly structurally abnormal RV, severe RV dysfunction, significant TR were the major hindrance for proper alignment echo beam exactly to the jet emerging from the site of obstruction in the RV. Therefore, invasive hemodynamic study was done to disclose the significant DCRV gradient. In our case, the abnormally hypertrophied muscle bundle was seen as a wedge-shaped filling defect with speckles of calcification in the RV angiogram in left lateral and anterior-posterior projection with shallow cranial angulation. Although our patient who had no other significant associated cardiovascular anomalies, the coexisting lesions may be subaortic stenosis, pulmonary valve stenosis, double-outlet RV, TOF, anomalous pulmonary venous drainage, complete or corrected transposition of the great vessels, pulmonary atresia with intact septum and Ebstein's anomaly and (rarely) anomalous coronary vessels which should be ruled out by sequential segmental analysis during vigilant echo. Sporadic cases have been described in patients with Down syndrome and Noonan syndrome. Noninvasive imaging such as contrast enhanced computed tomography and magnetic resonance imaging with three-dimensional printing may improve diagnosis in future.[111213]

Resection of the anomalous muscle can be approached through a right atriotomy, a right ventriculotomy, or a combined transatrial–transpulmonary incision.[6] The right atriotomy and the combined transatrial–transpulmonary incisions are the most commonly used approaches. Right ventriculotomy is usually avoided to reduce ventricular arrhythmias or RV dysfunction. However, it can still be used in patients whose obstructions are severe and too bulky to be excised through right atriotomy. The option to choose a preferable surgical approach can be well decided preceding to surgery is possible by proper evaluation as in our case.

Conclusion

Through echo supports, the morphological diagnosis of DCRV with delayed presentation; however, the gradient across RV outflow tract by echo is unreliable because of improper alignment of echo beam to the jet from the site of obstruction. Disfigured RV significantly hypertrophied muscle bundle with fibrosis with or without calcification, significant TR and dysfunction of RV are the major limitation to find proper gradient by echo in such patients. Therefore, invasive hemodynamic study is must to rule out significant gradient.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.