RETROGRADE CORONARY SINUS PERFUSION PROVIDES NONHOMOGENEOUS MYOCARDIAL BLOOD-FLOW

The ability of retrograde cardioplegia to protect the right ventricle has been questioned. Canine myocardial circulation was assessed by inf using colored microspheres through the coronary sinus. The relative fl ow index (RFI), a normalized measure of tissue blood flow, was determi ned for 76 sections of myocardium. Three distinct flow regions were ev ident from the measurements. A paucity of blood flow through some basa l sections of the right ventricle (RFI = 0.23 +/- 0.19) was found to b e significantly different (p < 0.005) from regions of the heart with n ormal flow (RFI = 1.12 +/- 0.06). Selections from the right ventricula r apex demonstrated augmented flow (RFI = 3.72 +/- 1.18). These data i ndicate that retrograde coronary perfusion provides nonuniform flow an d under some conditions may provide inadequate perfusion to portions o f the right ventricle.