Direct mechanical ventricular assistance during ventricular fibrillation

Abstract

A technique of direct mechanical ventricular assistance (DMVA) has been available since 1966. Ventricular assistance is provided by a glass cup lined with a Silastic diaphragm. It is held on the cardiac ventricles by suction. Alternating positive and negative pressure in the space between the cup and the diaphragm provides a pumping mechanism for blood flow. DMVA was compared to closed chest massage (CCM) and open chest massage (OCM) during ventricular fibrillation in six dogs. Each technique was applied for 10 minutes. Three dogs had CCM followed by OCM and then DMVA. Three dogs had only OCM and DMVA. Blood pressure and cardiac output were measured. All variables were calculated as a percentage of pre-ventricular-fibrillation values. Mean blood pressure was 19.7% with CCM, 39.8% with OCM, and 55.1% with DMVA. Systolic blood pressure was 25.8% with CCM, 51.9% with OCM, and 64.0% with DMVA. Diastolic blood pressure was 17.3% with CCM, 37.3% with OCM, and 48.9% with DMVA. Cardiac output was 13.8% with CCM, 37.1% with OCM, and 58.0% with DMVA. For each variable, OCM produced statistically higher values than did CCM. DMVA produced statistically higher values than did OCM for all variables. These preliminary results suggest that DMVA may be superior to currently available methods of cardiac massage during ventricular fibrillation.