CORONARY SINUS PRESSURE AND ARTERIAL VENTING DO NOT AFFECT RETROGRADECARDIOPLEGIA DISTRIBUTION

Retrograde techniques for the administration of cardioplegia solutions are of interest because of their relative practical convenience, and because of the possibility that they provide better delivery to myocar dial regions jeopardized by coronary stenosis than can be achieved wit h traditional antegrade techniques. This study was designed to test th e following three hypotheses about how the distribution of cardioplegi a by retrograde techniques might be optimized: (1) venting an occluded coronary artery improves the distribution of cardioplegia to the myoc ardial region originally supplied by it; (2) increasing the coronary s inus perfusion pressure makes the distribution of cardioplegia through the myocardium more uniform; and (3) increasing the driving pressure, as achieved by increasing the coronary sinus perfusion pressure or oc cluding a left coronary artery, improves the distribution of now to th e right ventricular free wall and interventricular septum. Tracer micr ospheres infused retrogradely with cardioplegia solution into canine h earts in vitro showed that the distribution of now through the coronar y sinus is consistently and significantly nonuniform, and is not signi ficantly altered by coronary arterial occlusion and venting, or by inc reases in coronary sinus perfusion pressure.