Myocardial performance early after aorto-coronary bypass surgery. Cardioplegic arrest versus coronary perfusion.
Haemodynamic adaptation was studied during the first 10 h after aorto-coronary bypass surgery. In a control group of 12 patients the heart was fibrillating and perfused during cardiopulmonary bypass (at 30 degrees C), and in 11 patients cold cardioplegic arrest was used. The first 4--5 h were characterized by rewarming, with increasing oesophageal temperature, cutaneous vasoconstriction and elevated systemic vascular resistance (SVR). A phase of vasodilation followed. In the control group the oxygen uptake index increased by 57% during rewarming, but the cardiac index (CI) was constant (about 2.9 l . min-1.m-2). The arterio-venous oxygen content difference (AVDo2) therefore increased (max. 3.0 mmol . l-1). The postoperative left ventricular performance was better and the serum levels of aspartate aminotransferase (ASAT) during the first 2 days postoperatively were lower in the cardioplegic patients than in the controls, indicating more efficient myocardial preservation. In the cardioplegic-hypothermic group, CI was constant at about 3.2 l . min-1.m-2 (significantly higher than in the control group) and AVDo2 remained normal during the rewarming period. The heart rate was lower initially in the cardioplegic patients than in the controls, implying a favourable influence on myocardial oxygen consumption. The better myocardial function in the cardioplegic-hypothermic group was associated with an only moderately increased SVR. This suggests that the elevated SVR in the control group could have been due to myocardial depression.
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D001831:Body Temperature; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D005260:Female; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D010101:Oxygen Consumption; D013318:Stroke Volume; D014655:Vascular Resistance