Cardiac pathology following resuscitative circulatory support. Direct mechanical ventricular actuation versus cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) is currently advocated for treating refractory cardiac arrest. Direct Mechanical Ventricular Actuation (DMVA) is an alternative method that does not contact the blood and has other unique advantages for providing resuscitative circulatory support, including rapid application and relative technical simplicity. The purpose of this study was to assess pathologic changes in the heart following resuscitation with either CPB or DMVA. Dogs (n = 22) received 1 hr of CPB (n = 11) or DMVA (n = 11) following a 12.5 min cardiac arrest. All deaths [4/11 (CPB) vs. 2/11 (DMVA), p = 0.31] occurred during the initial 24 postoperative hours. At 7 days, survivors had magnetic resonance imaging to determine cardiac ejection fraction [46% (CPB) vs. 51% (DMVA), p = 0.39], as well as the presence of cardiac wall motion abnormalities [50% (CPB) vs. 33% (DMVA), p = 0.57] and gross cardiac lesions [17% (CPB) vs. 17% (DMVA)]. The survivor's hearts were then extirpated, fixed, and examined for gross lesions [2/7 (CPB) vs. 0/9 (DMVA), p = 0.17]. Transmural sections of the anterior and posterior papillary muscles were histologically evaluated. The severity and extent of epicardial fibrosis and focal myocyte necrosis did not differ between groups. These data demonstrate that DMVA does not cause more myocardial trauma than CPB when used to provide resuscitative circulatory support. Therefore, the unique attributes of DMVA may improve resuscitation outcome in patients who suffer refractory cardiac arrest, without additional risk of cardiac injury.