Evidences for Inotropic Effects Induced by Simultaneous Antegrade and Retrograde Myocardial Perfusion in a Swine Model: Potential Applications for ECMO

Cardioplegia is administered via retrograde perfusion into the coronary sinus. We created a pig beating-heart model of self-myocardial retroperfusion (SMR) that used the venous pathway to boost the left ventricle's myocardial oxygenation. Then, in comparison to a single antegrade myocardial supply, we sought to assess if the combination of antegrade and retrograde myocardial perfusion with oxygenated blood may cause hemodynamic and cardiac responses. Eight pigs were assigned to receive SMR with antegrade physiological LAD perfusion at the same time. After closure of the left azygos vein (LAV), SMR was performed using a bypass line between the ascending aorta and the coronary sinus to provide selective retrograde perfusion of the great cardiac vein with oxygenated blood. Cardiac output (CO), maximal pressure in the LV (Pmax in-LV), stroke volume (SV), left ventricular ejection fraction (LVEF), diastolic durations (DD), heart rate (HR), and arterial systemic pressure were monitored with conductance catheters. These data were collected during the antegrade physiological myocardial perfusion (baseline period) and during a simultaneous antegrade and retrograde perfusion (SMR). SMR with simultaneous antegrade LAD perfusion showed inotropic properties with significant improvements in CO, SV, Pmax in-LV and LVEF (p<0.0001) compared with baseline values. Histology confirmed no evidences of tissular injuries. The selective retrograde perfusion of the great cardiac vein with oxygenated blood (SMR), paired with antegrade physiological LAD perfusion, demonstrated clear abilities to activate inotropic effects, bringing up new possibilities for cardiac assistance.