The end of the cold era: from intermittent cold to intermittent warm bloodcardioplegia

Background: A major reduction in the energy demand of the myocardium result s from the electromechanical arrest, and cooling contributes to a lesser de gree to this reduction. It is from this assumption that strategies of myoca rdial protection, utilizing warm blood cardioplegic induction, followed by cold cardioplegia with terminal warm reperfusion before removal of the aort ic cross clamp, became established as optimal myocardial protection. Contin uous normothermic perfusion 'closed the loop' by avoiding myocardial ischem ia and linking warm induction and terminal reperfusion. A series of laborat ory and clinical data confirmed the benefits of warm heart surgery on myoca rdial function and metabolism. The disadvantages of continuous warm blood c ardioplegia including disturbance of the operative field, led surgeons to a dminister warm hyperkalaemic blood intermittently as a new cardioplegic str ategy. Methods: This review examines the laboratory and clinical data with reference to the intermittent warm blood cardioplegia, to establish its exp erimental basis and place in clinical practice. Conclusions: Experimental o bservation and clinical application have established intermittent warm bloo d cardioplegia as a practical, effective and cheap myocardial protection te chnique, particulary with reference to coronary artery surgery. (C) 1998 El sevier Science B.V. All rights reserved.