VENTRICULAR-FUNCTION AFTER NORMOTHERMIC VERSUS HYPOTHERMIC CARDIOPLEGIA

Warm cardioplegia produced by essentially continuous infusion has been used as an alternative to traditional cold intermittent infusion tech niques during cardiac surgery, but its effects on postoperative left v entricular function have not been defined. We performed a randomized c linical trial to assess the effects of warm and cold blood cardioplegi a on load-independent indices of ventricular function. Fifty-three pat ients were randomized to warm (n = 27) or cold (n = 26) cardioplegia. Myocardial oxygen consumption, lactate production, adenine nucleotides , and adenine nucleotide degradation products were measured during car dioplegia and reperfusion. In 13 patients per group, pressure-volume l oops were constructed and ventricular function was assessed 3 hours af ter the operation. Warm cardioplegia resulted in greater myocardial la ctate production but improved recovery of oxygen consumption during re perfusion. Depletion of adenosine triphosphate was similar between gro ups, but total adenine nucleotides (adenosine triphosphate + adenosine diphosphate + adenosine monophosphate) fell further during warm cardi oplegia. Cold cardioplegia was associated with an accumulation of aden osine diphosphate and adenosine monophosphate. Creatine kinase MB isoe nzyme release was reduced in the warm group. Three hours after the ope ration, end-systolic elastance and preload-recruitable stroke work ind ex were increased after warm cardioplegia, and early diastolic relaxat ion was also increased. Increased systolic function after warm cardiop legia may have been related to improved myocardial protection, elevate d arterial lactate concentrations, or increased circulating catecholam ine levels. Altered diastolic compliance in the warm group may reflect greater active relaxation during early diastolic filling.