Reduction of myocardial infarct size: comparison between left atrial and left ventricular bypass.

Abstract

A controlled study was undertaken to quantitate and compare the effect of left ventricular bypass (LVB) and left atrial bypass (LAB on left ventricular infarct volume (LVIV). After baseline studies, the left anterior descending coronary artery in each of 30 mongrel dogs was ligated 1-1.5 cm from its origin. After baseline ischemic studies, control dogs (group 1--10 dogs), LAB dogs (group 2--10 dogs), and LVB dogs (group 3--10 dogs) were monitored for four hours. Final infarct size was determined by the nitroblue tetrazolium staining technique. Heart rate, mean arterial pressure, and total systemic flow (TSF) showed no significant difference between control and left heart bypass groups. In group 1, the LVIV was 27.7 +/- 6.5 g/100 g left ventricle (LV). In group 2, left heart bypass (LHB) flow was 90 +/- 4% of TSF. The pressure time index (PTI) was 2845 +/- 52 mm Hg-sec/min. The PTI demonstrated no significant difference from cntrols. In group 2, LVIV was 22.5 +/- 6.0 g/100 g LV. LVIV was reduced 18.8% from controls (p less than 0.08). In group 2, LHB was complete. Left ventricular decompression (group 3) resulted in a PTI of 328 +/- 76 mm Hg-sec/min. The PTI was significantly different (p less than 0.001) from groups 1 and 2. The LVIV was 12.6 +/- 5.1 g/100 g LV. LVIV was reduced 54.5% from controls (p less than 0.001) and 44.0% from group 2 (p less than 0.001). These results suggest that LVB may be useful, not only in supporting the circulation in the patient with myocardial infarct and cardiogenic shock, but also in limiting infarct size.

The Impact of Pump Speed and Inlet Cannulation Site on Left Ventricular Unloading with a Rotary Blood Pump

“…A similar conclusion, however, was drawn earlier by Pennock et al. (23), and Dennis et al. and Pierce et al.…”

Cannula Selection and Cannulation Techniques for Nonpulsatile Mechanical Ventricular Assistance

“…Left ventricular apex inflow cannulation optimizes left ventricular unloading (12) and results in a greater reduction in myocardial oxygen consumption than does left atrial inflow cannulation (13). Left ventricular to aortic bypass has also been shown to reduce the size of an evolving myocardial infarction when compared with left atrial to aortic bypass (13,14). As cardiac transplantation became reestablished in the early 1980s, an added advantage in patients requiring a mechanical bridge to transplantation was that a left ventricular apex cannula site could be removed in its entirety at the time of recipient cardiectomy .…”

Left-Ventricular Unloading by Transvalvular Axial Flow Pumping in Experimental Cardiogenic Shock and during Regional Myocardial Ischemia

“…Other authors reported on a significant reduction of infarct size using left heart bypass with direct drain age of the left ventricle in experimental myo cardial infarction [11,12]. However, with the exception of some successful use in weaning from cardiopulmonary bypass, application of these systems in patients with cardiogenic shock after myocardial infarction has been problematic requiring thoracotomy and re mained without major clinical success, so far.…”