Currently, the methods for detection of DCRV with VSD, besides echocardiography are Cardiac catheterization, cardiac CT and cardiac MRI (Figure 2, 3, 4).

DCRV is a rare condition seen in only 0.5-2.0% of all cases of congenital heart disease and is most frequently encountered in infants and children [2, 3, 10]. While cases have been found in adults, these might be due to missed diagnoses during infancy rather than novel onset later in life [2, 11].

An isolated DCRV is very rare, representing only in 6.2% of the patients, while approximately 80-90% of the DCRV cases are associated with various congenital heart defects, with ventricular septal defect (VSD), in particular, a perimembranous type VSD, being the most common. According to Hoffman, the most frequent associated congenital heart defect in DCRV patients was VSD, which accounted for 84.4%, followed by membranous subaortic stenosis (31.3%) [2].

DCRV can also be an associated anomaly of Williams’s syndrome. [12].This anomaly is often diagnosed during childhood and adolescence, while very few were found in adults [13]. Here, we are presenting a rare case report of a 7-month male child suffering from DCRV along with the co-existence of unorthodox and non-conventional large apical muscular VSD.

Figure 2: Cardiac catheterisation and RV angiography in a patient with DCRV, in lateral view the two chambers within the right ventricle, divided by hypertrophied septoparietal musculature. RV |,proximal RV chamber,RV ||, distal RV chamber , RA - right atrium, PA - pulmonary artery, PV - pulmonary valve.

The vaccination of mother and child was appropriately carried out, at the date of presentation to us.

There was no history of maternal risk factors for CHD (morbid obesity, diabetes, febrile illness, smoking, alcohol intake, teratogenic drugs use, or radiation exposure).

On deep interrogation, the parents informed that the child was having recurrent chest infections, failure to thrive and chest retractions during chest infections.

On clinical examination he was weighing 5.5 kg, weight 42 cm, BP 90/60 mmHg, Pulse rate 113/min, RR 25/min and SPO2 99% at room air. The child was of average built mildly tachypneic and irritable (Figure 5), without any evident chest retractions, cyanosis, clubbing or signs of heart failure. There was an absence of musculoskeletal anomalies. All the peripheral pulses were normally palpable without any radio-femoral delay.

Meanwhile, the respiratory system, central nervous system and abdomen were also examined and no abnormality was detected.

Figure 5: In our case - a 7-month male child afflicted with DCRV and Large apical VSD.

Figure 8: Suprasternal view - There are left aortic arch without any evidence of COA or PDA.

In the modified SX view (Figure 9), a distinctive large apical muscular VSD of size 7.4 mm was precisely delineated.

Moreover, in the apical 4CH and modified 4CH view, we could clearly demarcate an apical VSD communicating with the RV apex, along with a notable and pronounced anomalous muscle bundle (AMB) (Figures 10 and 11 respectively), lying just proximal to the apical VSD.

This AMB divided RV into two chambers: 1) small RV apical chamber (lower chamber) and 2) normal-sized basal RV chamber (upper chamber), consisting of RV inflow and RV inflow and RV cavity.

RV apex was resembling, as if it is a continuation of the apical region of LV, because of the presence of large conspicuous VSD. 

Figure 9: Modified SX view - Arrows demarcate an apical large VSD communicating with RV apex, ** asterix - denotes LV apex.

Color Doppler echocardiography (CDE) on dual mode imaging revealed spectacular and magnificent echo images with laminar flow across large apical VSD and turbulent, mosaic pattern flow across AMB (Figure 12)

In the right coloured panel, 2 angulated arrows point to the non-turbulent left to right flow across VSD and 3 angulated arrows indicate a highly turbulent mosaic pattern flow across AMB.

On CDE the direction of blood flow was from left to right across the VSD and subsequently from the lower, apical RV chamber to the upper, basal RV chamber across a severely restricting AMB.

This direction of flow is in contrast to the usual flow in DCRV- from the RV base to the RV apex (Figure 13).

Figure 13: An anatomical illustration of DCRV showing a pattern of blood flow (in green colour) in a usual patient.

The image distinctly shows that the RV blood flows from a proximal high-pressure chamber (basal chamber) into a distal low-pressure chamber (apical chamber) via a restrictive AMB

On CW doppler, the peak velocity of the VSD jet was 1.69 m/sec with a peak gradient of 11.4 mmHg (Figure 14)

Figure 16. SX View at the level of AO valve.

The pulmonary valve is normal and the main and branch pulmonary arteries are dilated. RVOT - right ventricular outflow tract, PVA - pulmonary valve annulus, MPA - main pulmonary artery, LPA - left pulmonary artery, RPA - right pulmonary artery, AO - aorta.

There was concentric hypertrophy of the RV without any dilatation and normal RV systolic function. The left ventricle was of normal size and the systolic function was also normal, LVEF 69%.

Because of the presence of a large apical VSD with restrictive AMB, with significant symptoms, the parents were advised that the child should undergo corrective surgery, in the form of patch closure of VSD and resection of AMB, at a tertiary care centre.

case, the muscle band in the RV apex divided the right ventricle into 2 chambers: 1) proximal chamber consisting of both RV inflow and RV cavity and 2) distal small RV apical chamber which was in communication with the left ventricular cavity via large non-restrictive apical muscular ventricular septal defect. The haemodynamic consequences and symptoms of the large non-restrictive ventricular septal defect were curtailed by the restrictive muscle band in the right ventricle. Overall clinically, echocardiographically and hemodynamically condition behaved like restrictive ventricular septal defect with left to right shunt.

The small apical muscular ventricular septal defect can close spontaneously but larger defects often persist and need treatment [19]. Though a number of cases of anomalous muscle band with typical DCRV have been reported in the literature; our case is atypical because of the presence of a proximal low-pressure chamber and a distal high-pressure RV apical chamber, which is just in contrast to the usual cases reported in the literature [5].

There was been one similar case reported in the literature, where an 11-year-old asymptomatic girl was found to have an apical muscular ventricular septal defect that was large but behaved like a small defect because of the restrictive flow across the anomalous muscle bundles in the right ventricular apex, and the patient was kept under medical follow up [20].

In the literature search, we also found another anatomically similar case wherein a 48-year-old male, echocardiography and magnetic resonance imaging revealed a large apical ventricular septal defect with separation of the right ventricular apex from the remaining RV by excessive trabeculations, thereby leading to the elimination of left to right shunt across the VSD. Physiologically there was no hemodynamic disturbance so the patient was kept under medical follow-up [21].

Therefore, this type of apical VSD along with apical muscle bands constitutes a rare and distinct type of morphology and physiology, and treatment needs to be individualized based on the hemodynamic disturbance it causes. Our patient was significantly symptomatic, hence we advised the parents of the child to seek an opinion from the department of Pediatric Cardiac Surgical unit of a tertiary care centre, for surgical resection of AMB with patch closure of the apical VSD.