Regional blood cardioplegic reperfusion during total vented bypass without thoracotomy: a new concept.

This study tests the hypothesis that immediate functional recovery is possible after 2 to 3 hours of regional ischemia by control of the conditions of reperfusion (i.e., total vented bypass) and the composition of the reperfusate (substrate-enriched blood cardioplegic solution) by either central cannulation with thoracotomy or peripheral cannulation without thoracotomy. Total vented bypass could be established successfully in each of 14 experiments (100%) in which the peripheral cannulation method was tested. Regional function (evaluated by ultrasonic crystals in open-chest animals) recovered comparably when substrate-enriched blood cardioplegic solution was given either globally or regionally (46% versus 36%) and total vented bypass was accomplished by either central cannulation or peripheral cannulation technique (i.e., left ventricle decompressed through a transaortic vent catheter, right atrium cannulated through the femoral vein, femoral artery perfusion). In contrast, systolic bulging persisted (-23% control systolic shortening) following normal blood reperfusion in beating, working hearts. Controlled reperfusion (either global or regional) also minimized postischemic edema (81% versus 83% water content, p less than 0.05). The effectiveness of controlled reperfusion (substrate-enriched blood cardioplegic solution during total vented bypass) versus uncontrolled reperfusion (normal blood in beating, working hearts) was assessed also in closed-chest dogs with 3 hours of regional ischemia (i.e., balloon inflation in the left anterior descending coronary artery). Results after controlled reperfusion showed complete recovery of contractility (as shown by echocardiography) at 24 hours, in comparison with only minimal recovery in three of eight dogs receiving uncontrolled reperfusion, and minimal histochemical damage (less than 5% triphenyltetrazolium chloride nonstaining), in comparison with 34% necrosis after uncontrolled reperfusion. These studies suggest that control of the reperfusion conditions and reperfusate composition can be achieved comparably in either the catheterization laboratory or the operating room, and a proposed clinical model for the treatment of patients with acute myocardial infarction is presented for evaluation.