Direct mechanical ventricular actuation for cardiac arrest in humans. A clinical feasibility trial.

Direct mechanical ventricular actuation (DMVA) is a non-blood-contacting method of biventricular cardiac massage which may be applied expediently for total circulatory support. The purpose of this study was to assess the feasibility of DMVA application for patients suffering refractory cardiac arrest. Following informed consent, DMVA was applied in 22 patients. Vascular access for hemodynamic monitoring was possible in only 12 patients, whose outcomes serve as the basis for this report. The mean age of the patients was 48.2 +/- 4.2 years (seven men; five women). The average time from witnessed cardiac arrest to DMVA application was 81 +/- 9 minutes. Application took less than two minutes from the time of skin incision and resulted in immediate hemodynamic improvement. Systolic and diastolic blood pressures averaged 78 +/- 4 and 41 +/- 4 mm Hg, respectively, with a mean cardiac output of 3.14 +/- 0.18 L/min during a mean of 228 +/- 84 minutes of circulatory support (range, 25 minutes to 18 hours). In selected cases the device was temporarily removed for 2 to 3 minutes and open-chest cardiac massage (OCCM) performed at similar compression rates. DMVA increased arterial pressures 65 percent and cardiac output 190 percent compared to OCCM. Initial arterial pH (7.12 +/- 0.04) improved by the time the device was removed (7.24 +/- 0.05). Serum lactate levels decreased from 18.0 +/- 2.3 mumol/L to 14.9 +/- 2.9 mumol/L. Four patients were successfully defibrillated: two had inadequate cardiac function and died within 1 h, and two were successfully resuscitated, but later died from cardiac failure and respiratory insufficiency. Another patient regained normal neurologic function during DMVA and was successfully bridged to cardiopulmonary bypass for emergent coronary artery bypass grafting, but died later from myocardial infarction. There were only two complications: (1) a cardiac laceration during pericardiotomy (1/22 patients); and (2) a ventricular rupture during OCCM (1/22). No complication resulted from the device. We found DMVA to be a feasible method for acute cardiovascular stabilization in victims suffering refractory cardiac arrest. Human clinical trials employing earlier DMVA application are required to determine its resuscitative potential.