Title
UNMASKING THE HIDDEN CHAMBERS: A DIAGNOSTIC CHALLENGE IN A PATIENT WITH DOWN'S SYNDROME AND DOUBLE CHAMBERED RIGHT VENTRICLE
Introduction
Double chambered right ventricle (DCRV) is a rare congenital/acquired cardiac anomaly that anatomically divides right ventricle (RV) into high-pressure (proximal) and low-pressure (distal) chambers, found in 0.5-2% of congenital heart disease cases. There are many causes, some of them being from anomalous muscle bands, hypertrophied trabecular tissue, or an aberrant moderator band, and it is often associated with other congenital defects, such as a ventricular septal defect (VSD) or tetralogy of Fallot (TOF). DCRV can also develop postnatally due to progressive hypertrophic changes in the RV's muscular structures.
Clinical Case
26-year-old female with Down syndrome came with dyspnea and dizziness. Initial vital signs were BP 136/84 mmHg, HR 87 bpm, RR 25 cycles/min, SpO2 80%, requiring supplemental oxygen. Exam revealed dysmorphic facial features, respiratory distress, rales, & holosystolic murmur with thrill. Electrocardiogram showed right bundle branch block and deep T wave inversions. Brain natriuretic peptide was 860 pg/ml. Transthoracic echocardiogram (TTE) revealed a large peri membranous VSD, double-chambered right ventricle with near cavity obliteration in systole, severe biventricular hypertrophy and subaortic membrane present just above the VSD. Peak gradient across pulmonary valve (PV) 121mmHg concerning for PV stenosis. She was treated medically for her heart failure and subsequently underwent surgery with right ventricular (RV) muscle resection, ventricular septal defect (VSD) repair with Gore Tex patch, subaortic membrane resection and creation of atrial septal fenestration. At 3 month follow up, despite TTE revealing failure of Gore Tex patch and recurrence of small VSD, patient remained acyanotic and asymptomatic with improved functional status.
Discussion
Our case was initially misdiagnosed as tetralogy of Fallot (TOF), a common misinterpretation of DCRV due to similar presentation. It is crucial to understand anatomical and hemodynamic differences in these two conditions. Location of VSD often helps with making associations. In TOF, the VSD jet is directed to the low-pressure chamber as opposed to isolated VSD, that is directed to the high-pressure chamber. Increased pressure gradient across PV is often misinterpreted as PV stenosis and pulmonary flow can help isolate TOF vs DCRV. TOF is associated with low flow across PV as opposed to isolated VSD. Surgery confirmed normal PV and annulus in this case. Although TTE was sufficient to diagnose this case, it is recommended to pursue additional imaging studies like transesophageal echocardiogram/cardiac MRI to prevent missing additional anomalies prior to surgical interventions. Surgical approach is the preferred treatment strategy. Accurate differentiation between DCRV & TOF is crucial for management, highlighting the need for comprehensive imaging evaluations