Skeletal muscle ventricles as left atrial-aortic pumps: short-term studies.
In 5 dogs, skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle and placed in the left hemithorax. After a 3-week vascular delay period, SMVs were electrically preconditioned with 2-Hz stimulation for 6 weeks. At a second operation, SMVs were connected between the left atrium and thoracic aorta by afferent and efferent aortic root homografts, and stimulated to contract in a 1:2 diastolic mode. At a mean left atrial pressure of 12.4 +/- 1.3 mm Hg and a burst stimulation frequency of 33 Hz, SMV stroke volume was initially 43% of that of the native left ventricle, achieving a flow equivalent to 21% of cardiac output (194 +/- 38 versus 902 +/- 85 mL/min). At 50-Hz stimulation, this figure rose to 27% (246 +/- 41 mL/min; p less than 0.05). Skeletal muscle ventricle power output (the product of stroke work and contraction rate) at 33 Hz was 0.016 +/- 0.003 W, increasing to 0.024 +/- 0.004 W at 50 Hz (p less than 0.05), corresponding to 14% and 22%, respectively, of left ventricular power output (0.11 +/- 0.012 W). After 4 hours of continuous pumping, four of the SMVs were still generating flows of more than 70% of starting values and more than 60% of initial power output. This study demonstrates that SMVs can function in the systemic circulation at physiologic left atrial preloads.
Hooper
T L
TL
Division of Cardiothoracic Surgery, Wayne State University, Detroit, Michigan 48225.
Niinami
H
H
Hammond
R L
RL
Lu
H
H
Ruggiero
R
R
Pochettino
A
A
Stephenson
L W
LW
D000818:Animals; D001011:Aorta / Q000601:surgery; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D006325:Heart Atria / Q000601:surgery; D006352:Heart Ventricles / Q000601:surgery*; D006439:Hemodynamics; D008722:Methods; D009119:Muscle Contraction; D009132:Muscles / Q000637:transplantation*; D010138:Pacemaker, Artificial