Comparison of isothermic and cold cardioplegia in cardiac surgery in Salem District

ABSTRACT

Background: Perioperative myocardial damage is one of the most common causes of morbidity and mortality after heart surgery. The improvement of the technique of myocardial preservation has contributed greatly to significant advances in cardiac surgery. However, serious questions remain regarding the use of warm versus cold cardioplegia, blood versus crystalloid cardioplegia, antegrade versus retrograde delivery and intermittent versus continuous perfusion. Cardioplegic solution is the means by which the ischemic myocardium is protected from cell death. This is achieved by reducing myocardial metabolism through a reduction in cardiac workload and by the use of hypothermia. Chemically, the high potassium concentration present in most cardioplegic solutions decreases the membrane resting potential of cardiac cells. The normal resting potential of ventricular myocytes is about -90 mV. Materials and methods: The study was conducted in the Department of Cardiothoracic Surgery, Government Mohan Kumaramangalam Medical College Hospital from 2016-2017. Thirty patients were selected and divided into two equal groups. Group I, Isothermic blood cardioplegia, patients were cooled to 30˚C, and cardioplegia given at the same temperature as circulating blood in cardiopulmonary bypass and repeated at 20 minutes. The cardioplegic heat exchanger was not utilized in the cardiopulmonary bypass circuit. In group II, conventional cold cardioplegia, patients were cooled to 28-30˚C. Cardioplegia was given at 7-10˚C and was repeated every 30 minutes. To assess myocardial metabolic activity, myocardial oxygen consumption (MVO2), myocardial glucose uptake, myocardial lactate, and acidosis were measured, using arterial and coronary venous blood samples. Results: Mean cardiopulmonary bypass time was significantly shorter receiving isothermic blood cardioplegia (69 v/s 96 minutes). Serum lactate after cardiopulmonary bypass in isothermic blood Pon. A. Rajarajan. Comparison of isothermic and cold cardioplegia in cardiac surgery in Salem District. IAIM, 2019; 6(3) 266-271. Page 267 cardioplegia was lower (1.9 v/s 2.9). There was less metabolic acidosis in the isothermic group (pH 7.37 v/s 7.34). Glucose uptake was higher in the isothermic group. Myocardial contractile function was slightly better in the isothermic group (Ejection Fraction -62 v/s 60 %). Conclusion: The aim of myocardial protection during heart surgery was to preserve myocardial function while providing a bloodless and motionless operating field. In the early stage, myocardial protection was obtained by decreasing myocardial oxygen demand as a consequence of hypothermia. Although intermittent cold cardioplegia perfusion is associated with excellent clinical outcomes in cardiac surgery, this standard technique results in myocardial hypothermia, ischemia and a delay in the recovery of postoperative myocardial metabolism and function. Myocardium utilizes more oxygen and glucose after isothermic cardioplegia, but lactate and acid production were less.