Inadequate Cardioplegic Protection with Obstructed Coronary Arteries

Abstract

To determine the contribution of complete cardioplegia to the preservation of left ventricular (LV) function, we put ultrasonic transducers in the anterior and posterior walls of the left ventricle in 18 dog hearts.The dogs were subjected to global ischemia for 60 minutes at 28"C, and the speed of segment shortening (dlldt) and percent of systolic shortening of the two wall regions before and after ischemic manipulations were measured.When cardioplegic perfusion was uniform, there was no significant difference between the anterior and posterior walls in any of the variables measured, and global LV function (stroke work) was well preserved.However, when the left anterior descending coronary artery was occluded during cardioplegic infusion, there was significant dysfunction after reperfusion of the anterior wall: without perfusion, the anterior segments recovered only 41% (5.9114.3mm1 sec) of preischemic dlldt, while the perfused anterior segments retained 78% (11.4114.6 mmlsec) of control dUdt ( p < 0.05).The experimental anterior regions regained only 36% of preischemic systolic shortening, while the anterior segments in the homogeneously perfused hearts were indistinguishable from internal controls ( p < 0.01).Regionally inadequate cardioplegic protection during coronary artery bypass graft operation may contribute to perioperative infarction and LV dysfunction, and appropriate timing of anastomoses to ensure early cardioplegic perfusion of all ischemic myocardium is important.Cardioplegia has been identified as an effective adjunct in the preservation of myocardial architecture [4, 10, 111, metabolic activity [ll,