Giant Heart in L-TGA with Ebstein-like Tricuspid Valve and Coarctation of the Aorta

Description of Clinical Presentation: A 16-year-old female with congenital transposition of the great arteries and severe post-ductal coarctation of the aorta (CoAo) had a prenatal diagnosis of CoAo that was surgically repaired in the neonatal period without subsequent re-coarctation. Additional findings included a muscular ventricular septal defect and an Ebstein-like malformation of the tricuspid valve.
She persisted in NYHA functional class II, reporting exertional fatigue, and was maintained on anticongestive therapy. From the age of 12, she developed recurrent episodes of symptomatic atrial flutter, temporarily reverting to sinus rhythm after electrical cardioversion. An electrophysiological study revealed multiple arrhythmic foci, which could not be successfully ablated. Despite antiarrhythmic therapy, she required repeated hospitalizations for rhythm-induced heart failure decompensation.

Diagnostic Techniques and Their Most Important Findings: Serial echocardiograms demonstrated severe tricuspid regurgitation due to deficient leaflet coaptation, with progressive left atrial (LA) enlargement. The right ventricle (RV), functioning as the systemic ventricle, was dilated and hypertrophied but had preserved systolic function. Proximal dilation of the left pulmonary artery branch (LPAB) was also noted. The subpulmonary left ventricle (LV) exhibited abnormal segmental contractility and mildly depressed systolic function. Computed tomography revealed an anomalous origin of the anterior descending coronary artery from the right coronary artery.

Cardiac magnetic resonance (CMR) imaging was performed using a 1.5T scanner. Cine steady-state free precession MRI sequences were used for structural and functional evaluation, and late gadolinium enhancement imaging was performed 10–15 minutes post-contrast to assess for fibrosis. Flow quantifications of atrioventricular valves were done. Quantitative measurements adhered to the Society for Cardiovascular Magnetic Resonance recommendations.
CMR imaging confirmed normal indexed volumes of the right atrium and LV, although the latter had a borderline ejection fraction. The LPAB showed a Z-score of +5.1. The LA was severely dilated, with an indexed volume seven times the upper limit of normal. The RV displayed marked architectural abnormalities, indexed volumes were three times the upper normal limits, and it had mildly reduced systolic function. Tricuspid annular dilation was associated with severe regurgitation (regurgitant fraction 80%).

Learning Points from this Case: This case highlights the essential role of CMR imaging in patients with complex congenital heart disease, allowing accurate assessment of chamber volumes, ventricular mass, and function, and structural abnormalities, even in severely enlarged and distorted ventricles. Quantification of tricuspid regurgitation by CMR provides important prognostic information in patients with valvular disease and complex anatomy that cannot be fully characterized by echocardiography.

Steady-state free precession – 2-chamber view: Left atrial enlargement (arrowhead) with dilated and hypertrophied right ventricle (arrow with tail).
Steady-state free precession – 4-chamber view: Marked left atrial enlargement (arrowhead), anterior leaflet downward displacement of tricuspid valve (dashed arrow), and hypertrophied right ventricle (arrow with tail).
Steady-state free precession – ventricular short axis: Dilation and hypertrophy of the right ventricle (arrow with tail), with ventricular septal deviation toward the left ventricle (dashed arrow).