Synchronized retroperfusion of coronary veins for circulatory support of jeopardized ischemic myocardium.

A retroperfusion system was developed that augments retrograde delivery of arterial blood into an acutely ischemic myocardial region during diastole and facilitates coronary venous drainage in systole. An electrocardiogram-synchronized, gas-actuated bladder pump propels retroperfusate through an autoinflatable balloon catheter whose tip is placed within the regional coronary vein that drains the ischemic myocardium. Experiments were performed in 26 closed chest dogs with 4 hour intracoronary balloon occlusion of the proximal left anterior descending coronary artery. An untreated control series consisted of 13 dogs; the remaining 13 dogs were treated with retroperfusion, which was initiated after the first hour of acute coronary occlusion. Synchronized retroperfusion resulted in a significant 37 +/- 10 per cent (mean +/- standard error of the mean) decrease in left ventricular end-diastolic pressure from 11 +/- 2 to 5 +/- 21 mm Hg, a 20 +/- 4 percent decrease in peak systolic pressure (140 +/- 7 to 110 +/- 6 mm Hg) and a 25 +/- 6 percent reduction in systemic vascular resistance (3,880 +/- 340 to 2,380 +/- 300 dynes sec cm-5). Ischemic region intracoronary S-T segment elevation decreased 40 +/- 15 percent, and potassium loss was reduced 92 +/- 22 percent. Partial pressure of oxygen measured distal to the coronary occlusion decreased 36 +/- 2 percent, suggesting oxygen delivery to and extraction by the jeopardized ischemic myocardium. Ventriculography in four dogs revealed an increase in left ventricular ejection fraction and reversal of ischemic segment dyskinesia by synchronized retroperfusion. A nitro-blue tetrazolium study of 10 excised hearts indicated that 3 hours of synchronized retroperfusion significantly reduced the size of ischemic injury to 3.3 +/- 2 percent of the left ventricle (versus 16.2 +/- 5 percent in the untreated control group). In addition, retroperfusion appeared to correct ischemic arrhythmias. The experimental data suggest that this treatment is capable of improving cardiac function and salvaging jeopardized myocardium. Clinical application is envisioned as a prompt temporary emergency support for acute and profound ischemic dysfunction not readily treatable by other interventions.