| Abstract: | Myocardial infarction following coronary occlusion limits the effectiveness of emergency coronary artery bypass operations. We designed and evaluated a transvenously introduced balloon-tipped catheter and an electrocardiogram-activated pumping system for perfusing ischemic myocardium by retrograde pulsation of oxygenated blood into the coronary veins during diastole. Balloon deflation during systole allowed for normal venous drainage. Four groups of dogs (n = 26) were instrumented with sonomicrometry crystals and catheters to measure regional and global left ventricular function. Two groups of dogs had chronic left ventricular (LVH) produced by prior aortic banding (left ventricular mass 174 gm versus 115 gm for control dogs of equal body weight, p less than or equal to 0.05). The left anterior descending coronary artery (LAD) was occluded for 40 minutes; after 10 minutes left ventricular function was severely depressed in all groups (less than or equal to 0.05 compared to baseline). Groups 1 (normal left ventricle, n = 8) and 2 (LVH, n = 5) had no further therapy for the following 30 minutes. Groups 3 (normal left ventricle, n = 8) and 4 (LVH, n = 5) received 30 minutes of coronary vein retroperfusion (CVRP) 10 minutes following the LAD occlusion. CVRP restored 37% of systolic shortening, whereas there was no restoration of systolic shortening in control dogs (p less than or equal to 0.001). All other physiological and hemodynamic parameters including heart rate, cardiac output, aortic pressure, dP/dt, and left ventricular dilatation were normalized during CVRP while remaining severely depressed in control dogs (p less than or equal to 0.05). Following restoration of arterial flow at 40 minutes, 10 of 13 CVRP-treated dogs recovered normal left ventricular function while only two of 13 untreated dogs survived. CVRP offers a transvenous approach for modifying myocardial ischemia prior to emergency coronary artery bypass grafting. |
