Fetal Diagnosis of Right Ventricular Aneurysm Associated With Supraventricular Tachycardia With Left Bundle-Branch Block Aberrancy
A36-week female fetus was referred for evaluation because of an irregular heart rate and a prenatal ultrasound that suggested an abnormal tricuspid valve and dilated right ventricle (RV). Fetal echocardiography demonstrated frequent atrial ectopy and an increased cardiothoracic ratio due to a relatively thin-walled, poorly contracting aneurysmal portion of the RV basal region and free wall (Figure 1). Maternal digoxin therapy was initiated. The baby was born at a gestational age of 37 weeks and weighed 4778 g. Transthoracic echocardiography confirmed the prenatal findings. Angiography demonstrated a large, trabeculated, poorly contracting RV chamber lateral to the tricuspid valve, covering and partially compressing the right atrium. Electrocardiography demonstrated frequent premature ventricular contractions and nonsustained supraventricular tachycardia with left bundle-branch block aberrancy, possibly because the RV aneurysm physically contacted the right atrium and functioned as an accessory connection (Figure 2). Sinus rhythm was achieved with amiodarone therapy. MRI and magnetic resonance angiography revealed aneurysmal dilatation of the RV basilar portion and proximal outflow tract (Figure 3). The RV free wall had hypertrophic areas interspersed with areas of thinning without obvious fatty infiltration. The patient was maintained on digoxin, amiodarone, and low-molecular-weight heparin. She remained asymptomatic and in sinus rhythm at follow-up. Echocardiography at 4 months of age revealed improved RV function; anticoagulation therapy was discontinued.
The differential diagnosis of prenatally detected RV aneurysm includes Uhl’s anomaly, arrhythmogenic RV dysplasia, atrialized RV myocardium in Ebstein’s anomaly, congenital absence of the right pericardium, and postischemic aneurysm. This case most likely represents an atypical presentation of arrhythmogenic RV dysplasia and demonstrates a potentially unique cardiac rhythm disturbance of supraventricular tachycardia with left bundle-branch block aberrancy due to physical contact of the aneurysm with the right atrial myocardium.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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