Apical ventricular septal defect with reverse bidirectional transseptal flow: a sign of restriction within the right ventricle.

Apical ventricular septal defects (VSD) may spontaneously become restricted or may even close following tissue outgrowth within the right ventricle in the region of the apical muscle bundles. We report a case of spontaneous restriction of an apical VSD localized within the right ventricle in the region of prominent apical trabeculae, in which pulsed Doppler interrogation showed an unusual pattern of bidirectional blood flow across the VSD, with right to left flow in systole and left to right in diastole. Angiography confirmed these unusual aspects. This reverse bidirectional transseptal flow is due to the physiological incorporation of the apical part of the right ventricular cavity in the left ventricle and may be, in the absence of right outflow obstruction, a sign of restriction of the VSD inside the right ventricle.