In vivo measurement of ventricular geometry during fibrillation

Both experimental and modeling studies have shown that ventricular geometry plays a role in the efficacy of defibrillation shocks. This study uses transthoracic echocardiography to measure the temporal changes in the geometry of the right ventricle (RV) during an episode of ventricular fibrillation (VF). The results show that the RV is characterized by a linear increase in short axis length and cross sectional area during the first 20 seconds of VF. Perimeter and long axis lengths showed no significant changes and a qualitative analysis of the left ventricle found no detectable geometric changes. These findings suggest that further study of changes in cardiac geometry and their effects on shock efficacy may be needed to fully understand the implications of this phenomena on catheter based defibrillation systems.