Is there any Benefit from Adding Single-Dose Cardioplegia to Topical Cooling of the Ischaemic Myocardium in Aortic Valve Replacement Operations?

Abstract

The myocardial oxygen extraction, lactate metabolism and cardiac performance were studied after topical cold myocardial ischaemia (TCI) with or without associated cold potassium cardioplegia (CPL) in aortic valve replacement (AVR) patients. There were no such differences between the CPL + TCI-group and the TCI-group in the postischaemic coronary sinus blood oxygen tension, coronary sinus blood haemoglobin oxygen saturation, arterial-coronary sinus blood oxygen content difference, arterial-coronary sinus blood lactate difference, CI-PCWP or LVSWI-PCWP relationship that could be attributed to the cardioplegia. The coronary sinus blood oxygen values did not indicate any gradually developing postischaemic disturbances in the myocardial oxygen utilization. There was, however, a marked myocardial lactate washout and production in both groups five and ten minutes after initiation of reperfusion after ischaemia. There was a marked increase in the CI after bypass in the CPL + TCI-group, and the cardiodepression at late post-operative stages was minimal in both groups according to the CI-PCWP and LVSWI-PCWP relationship. These results suggest that the topical cooling technique used provides a degree of protection of the myocardial energy metabolism and function that cannot be further improved by adding single-dose cardioplegia by means of the direct coronary cannulation method used here.