(245) Uncommon Cause of Right Ventricular Failure: A Case Report of Sinus Venosus Atrial Septal Defect

Introduction: Sinus Venosus atrial septal defect (SVASD) is an infrequent congenital heart disease, accounting for 4 to 11% of all atrial septal defects (ASD). Caused by a defective wall between superior vena cava and right-sided pulmonary veins and is commonly associated with anomalous pulmonary venous return (APVR). It can cause exertional dyspnea, atrial arrhythmias, volume overload and pulmonary hypertension (pHTN). Diagnosing SVASD can be challenging, since typically not seen in transthoracic echocardiography or tomography scans and is often discovered incidentally in transesophageal echocardiography (TEE).

Description: A 79-year old female as medical history of coronary artery disease, chronic respiratory failure on 4LNC, pHTN and right ventricular (RV) dysfunction, prior pulmonary embolism (PE), restrictive lung disease (RLD) due to scoliosis, and atrial fibrillation (Afib) admitted with dyspnea and acute hypoxemic respiratory failure. Initial chest tomography ruled out PE and showed pulmonary edema, thus managed with diuresis. Evaluated by cardiology, that opted for TEE and cardioversion (CV) followed by watchman device placement. Immediately after CV, her course was complicated by worsening hypoxemia and intensive care unit admission for impending respiratory arrest. Due to concerns of shunting, revision of TEE, SVASD with bidimensional shunting and severely dilated RV was seen. She was transferred to quaternary hospital for right and left heart catheterization (RLHC) and surgical planning. RLHC was consistent with SVASD and partial APVR and pre and post capillary pHTN. Shunt fraction of 2.2 and mixed venous oxygen 54-57% favored surgical correction but deemed high risk due to severe RLD, thus to proceed with rehabilitation in preparation surgical management.

Discussion: This case highlights the need for a high level of suspicion when severe hypoxemia and RV dilation is present, as SVASD is typically not seen in TTE or tomography scans. Initial stabilization involves prompt recognition and volume control with diuresis. The decision for surgery is based on degree of symptoms, shunting and pHTN but limited if RV dysfunction is seen as surgery may not reflex increased quality of life, necessitating an individualized approach, especially in frail and critically ill patients.