Intrathoracic Skeletal Muscle Ventricles: A Feasibility Study

For skeletal muscle ventricles (SMVs) to be applied clinically, it is likely that they will have to be placed within the chest. Ease of subsequent connection to the circulation, and avoidance of significant lung compression, are factors that could influence SMV size and shape in a way that may prejudice their ability to pump effectively at physiological preloads. In five dogs, specially designed SMVs were constructed from the latissimus dorsi muscle, and placed in the apex of the left hemithorax. After a 3-week delay, the muscle was preconditioned electrically by 2-Hz continuous stimulation for 6 weeks. At a later thoracotomy, this positioning of SMVs permitted easy surgical access to the heart and great vessels. SMVs were then connected to a mock circulation device for functional evaluation. As right-sided pumps, at a preload of 10 mmHg, SMVs generated a stroke volume (SV) and stroke work (SW) exceeding that of the native right ventricle (SV = 8.9 ± 0.8 vs 7.9 ± 0.6 mL; SW = 0.44 ± 0.03 vs 0.20 ergs x 106). As left-sided pumps, also at a preload of 10 mmHg, SMV SV, and SW was roughly half that of the left ventricle (SV = 3.7 ± 0.2 vs 7.9 ± 0.6 mL; SW = 0.29 ± 0.03 vs 0.57 ± 0.05 ergs x 106). SMVs may conveniently be positioned inside the chest, where they have the potential to function as left or right heart assist devices.