Skeletal muscle–powered ventricle: Effects of size and configuration on ventricular function

Abstract

The optimal size and configuration of skeletal muscle-powered ventricles are still undetermined. This study was aimed at comparing three types of skeletal muscle-powered ventricle: (A) a small size (15 ml capacity) double-layered pump, (B) a small size (15 ml capacity) single-layered pump, and (C) a large size (40 to 60 ml capacity) single-layered pump constructed sequentially with the same untrained latissimus dorsi muscle of 12 mongrel dogs. The skeletal muscle-powered ventricle was connected to a mock circulation system, the stroke volumes against 40 to 160 mm Hg of afterload at 5 to 60 mm Hg of preload were measured, and the stroke work was computer analyzed on line. Raising the preload from 5 to 60 mm Hg increased the peak isovolumic developed pressure (A) from 91.3 +/- 11.0 to 215.6 +/- 26.1 mm Hg, (B) from 92.8 +/- 12.0 to 166.3 +/- 19.0 mm Hg, and (C) from 32.3 +/- 5.2 to 121.4 +/- 15.5 mm Hg (p < 0.05, C versus A and B). Similarly, the stroke volume (stroke work) against an afterload of 120 mm Hg increased (A) from 3.8 +/- 0.5 ml (0.22 +/- 0.04 x 10(6) ergs) to 14.5 +/- 1.1 ml (1.05 +/- 0.11 x 10(6) ergs), (B) from 4.5 +/- 0.7 ml (0.30 +/- 0.08 x 10(6) ergs) to 10.7 +/- 0.9 ml (0.63 +/- 0.08 x 10(6) ergs), and (C) from 1.8 +/- 0.5 ml (0.09 +/- 0.04 x 10(6) ergs) to 24.0 +/- 3.6 ml (1.94 +/- 0.41 x 10(6) ergs) (p < 0.05, C versus B at 5 mm Hg of preload; p < 0.05, C versus A and B at preloads > or = 30 mm Hg). At low preloads (5 to 15 mm Hg) both small pumps generated a significantly larger stroke volume (stroke work) than the large pump, whereas at high preloads (> or = 30 mm Hg) the large pump generated a significantly larger stroke volume (stroke work) than the small pumps. It is concluded that under physiologic preload, B (small single-layered pump) performs better than or at least as well as A (small double-layered pump) and C (large single-layered pump), despite being constructed with only one half of the muscle mass used for either A or C.