Right ventricular function after normothermic versus hypothermic cardiopulmonary bypass

Abstract

Normothermic systemic perfusion in patients undergoing cardiopulmonary bypass may compromise myocardial hypothermia, a mainstay for preservation of ventricular function during iatrogenic cardiac arrest. The right ventricle is the area of the heart most susceptible to rewarming. We prospectively evaluated myocardial rewarming and indexes of right ventricular function in 30 patients undergoing coronary artery bypass grafting randomized to receive moderate hypothermic (bladder temperature 25 degrees C) or normothermic perfusion and multidose cold blood cardioplegia during cardiopulmonary bypass. All patients had significant stenosis (> 70%) of the right coronary artery, and in 27 of 30 the right coronary artery was revascularized. A right ventricular ejection fraction/volumetric catheter was used to assess right ventricular function by right ventricular ejection fraction and a preload (right ventricular end-diastolic volume) normalized right ventricular stoke work index in the prebypass and postbypass periods. Findings included the following: (1) Greater rewarming of all areas of the heart occurs with normothermic bypass, with the mean temperature difference at the end of each intracardioplegic period ranging from 4.0 degrees to 6.3 degrees C warmer than with hypothermic bypass; (2) the right ventricle was not more susceptible to rewarming than the posterior left ventricle or interventricular septum in either group; (3) right ventricular function did not differ between groups at any time in the study, including the immediate postarrest period; and (4) right ventricular function was preserved and equivalent to the prebypass baseline. We conclude that the moderate myocardial rewarming that occurs with normothermic perfusion does not compromise right ventricular preservation in patients with right coronary artery disease undergoing revascularization with multidose cold blood cardioplegia to maintain electromechanical arrest.