Parallel Running Two-way Right Ventricles as a Cause of Refractory Right Heart Failure.

Abstract

From the viewpoint of developmental biology, the right ventricle is composed of three portions, the inlet, the outlet, and the apical trabecular portion. Bloodstream flows in from the inlet, passes through the trabecular portion, and flows out from the outlet. Here we report the unique muscular division of the right ventricle, which divided the apical trabecular portion from the rest of the right ventricle. This unique division was different from double chambered right ventricle (DCRV), an occasionally observed muscular division of the right ventricle, in the lack of intraventricular pressure gradient. We report the successful diagnosis of this unique division of the right ventricle, which looks like parallel running two-way right ventricles, with imaging modalities. A 59-year-old man presented with a 15-year history of refractory right heart failure accompanied by leg oedema and dyspnoea on exertion. He underwent surgical thoracotomy 10 years ago to remove a right atrial thrombosis in association with the highly enlarged right atrium; however, his subjective symptoms and oedema persisted following the surgery. Electrocardiogram is shown in Supplementary Figure 1. Transthoracic echocardiography revealed muscular division of right ventricle, suggesting the diagnosis of DCRV (Figure 1A). Usually, diagnosis of DCRV is made by proving the existence of muscular stenosis within right ventricle and consequent intraventricular pressure gradient via imaging modalities and right heart catheterisation [1]. Right heart