Fetal right ventricular aneurysm caused by chronic progressive myocardial ischemia

Congenital ventricular aneurysm in the fetal heart is rare and little is known about its etiology. We report a case of right ventricular (RV) free-wall aneurysm secondary to myocardial ischemia confirmed by postmortem histological examination. During routine ultrasound examination at 25 weeks' gestation in a healthy 33-year-old pregnant woman, gravida 2 para 1, a large thin-walled outpouching of the RV free wall was identified in the fetus which had previously appeared normal at 20 weeks. The RV apex had normal thickness (Figure 1a,b) and there was no additional cardiac structural abnormality. RV systolic function was impaired due to the hypokinetic aneurysmal free wall. Left ventricular systolic function was good with normal Doppler filling patterns, but a prolonged left ventricular Tei index (0.57). Ductal flow was bidirectional and predominantly right to left. Diastolic functional parameters were normal on pulsed-wave Doppler assessment of tricuspid inflow, hepatic vein and ductus venosus flow. Cardiac rhythm was sinus and there was no hydrops. In view of the potential adverse outcome, including risk of heart failure and thromboembolism, the parents opted for termination of pregnancy at 28 weeks. On postmortem examination of the fetus, an aneurysmal dilatation (25 × 15 × 5 mm) of the RV free wall filled by an adherent blood clot was observed. The left ventricle was normal and the ventricular septum was intact. The foramen ovale was dilated. The RV myocardium consisted of attenuated myocardial bundles, haphazardly intermingled with broad bands of collagen fibers. Coronary arteries in close association with the aneurysm showed significant luminal narrowing from fibrointimal hyperplasia and medial hypertrophy (Figure 1c–e). There was no adipose infiltration and no evidence of myocarditis or viral inclusions. The histological appearances suggested extensive RV ischemic damage secondary to progressive chronic myocardial insufficiency. Fetal cardiac aneurysms and diverticula are rare with poorly described long-term outcomes1. When located in the right heart, causes are speculated to be secondary to myocardial injury caused by a coronary event, infection or, even rarer, arrhythmogenic RV cardiomyopathy or Uhl's anomaly2, 3. The cause is often unproven and the outcome challenging to predict, which makes counseling extremely difficult. To our knowledge, this is the first case with supported causative histological evidence. Our case had occlusion of proximal to mid-right coronary artery (RCA) territory which caused myocardial injury and fibrous remodeling/infiltration. The echocardiographic appearance of the poorly contracting RV free wall corresponds to the territorial supply of the RCA. The cause may have been in-situ thrombosis or a paradoxical embolism. Myocardial infarction in the fetus often results in devastating consequences. Of those surviving to birth, the neonatal mortality may be as high as 80%4. Recovery of cardiac function is unlikely as this often relies on the patency of the coronary artery to resume perfusion and reverse remodeling. Transplantation is a potential therapeutic option, however, organ availability is scarce and the waiting list attrition is high. With histological evidence, we have gained novel insight into the pathological mechanism of fetal RV aneurysm, which may help with targeted management options in the future. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.