Effects of 1:1, 1:2 or 1:3 intra-aortic balloon counterpulsation/heart support on coronary haemodynamics and cardiac contractile efficiency in an animal model of myocardial ischaemia/reperfusion.

OBJECTIVES The effects of operational modes of intra-aortic balloon pumping (IABP) on coronary haemodynamics and oxygen delivery/demand ratio are unknown and were investigated in an experimental model of myocardial ischaemia reperfusion. METHODS Healthy swine (n = 24) underwent 120-minute ligation of the left anterior descending coronary artery followed by 24 h of reperfusion and were randomly assigned to have IABP 1:1 (n = 6), IABP 1:2 (n = 6), IABP 1:3 (n = 6) in the descending aorta or to no IABP implantation (n = 6) 5 min after the onset of reperfusion. Systolic (CBF(Sys)) and diastolic (CBF(Dia)) coronary blood flow, systolic (CR(Sys)) and diastolic (CR(Dia)) coronary resistances and endocardial viability ratio (EVR), as an expression of the oxygen delivery/demand ratio, were measured at 30 min, 1, 6, 12 and 24 h after coronary reperfusion, respectively. RESULTS IABP at the 1:1 operational mode significantly increased CBF(Dia) and EVR, and reduced CR(Dia) throughout the experiment. Contrastingly, IABP at 1:3 mode resulted in a significant reduction in CBF(Dia), in a steady increase in CR(Dia), in a steady reduction in O(2) delivery and a constant increase in O(2) demand over time. IABP at the 1:2 mode had no overall effect on assessed parameters. CONCLUSIONS IABP at the 1:1 mode enhanced coronary haemodynamics and cardiac contractile efficiency in an acute animal model of coronary ischaemia/reperfusion. On the contrary, IABP support set at the 1:2 or 1:3 modes failed to provide benefit. Progressive reduction in balloon inflation with a 1:1 mode instead of decreasing the heart/IABP operational ratio might represent a better IABP withdrawal protocol and is currently under investigation.