Kochamba G, Desrosiers C, Dewar M, Chiu R C
Division of Cardiovascular and Thoracic Surgery, Montreal General Hospital/McGill University, Que, Canada.
Ann Thorac Surg. 1988 Jun;45(6):620-5. doi: 10.1016/s0003-4975(10)64762-5.
To enable long-term studies of a totally implantable cardiac assist device powered by transformed fatigue-resistant skeletal muscle, we developed a dual-chamber extraaortic counterpulsator implanted, 2 of which fluid for power transfer. Six dogs had our dual-chamber extraaortic counterpulsator implanted, 2 of which had undergone prior transformation of their latissimus dorsi muscle. The blood pump, with a Dacron graft at each end, was anastomosed end-to-side and parallel to the thoracic aorta, allowing continuous blood flow to minimize thrombus formation caused by stasis and turbulence. The blood pump was powered by a hydraulic bulb placed beneath the latissimus dorsi muscle. The latissimus dorsi muscle was stimulated to contract during diastole using a synchronized burst electrical stimulator. The ratio of diastolic pressure time product over systolic time tension index, which reflects the myocardial oxygen supply and demand ratio, was calculated from ascending aortic pressure tracings. A consistent increase in this ratio of 44% in 4 dogs with nontransformed latissimus dorsi muscle and of 70% in 2 dogs with transformed latissimus dorsi muscle was obtained when the device was activated. Preliminary chronic implantation studies using a Medtronic cardiomyostimulator (Model SP1005) as the burst stimulator for our dual-chamber extraaortic counterpulsator produced an average augmentation in aortic diastolic pressure of 34 mm Hg for up to six days. Our results indicate that, with further refinement of this device, a long-term totally implantable cardiac assist device powered by endogenous skeletal muscle will be feasible.
为了对由转化后的抗疲劳骨骼肌驱动的完全植入式心脏辅助装置进行长期研究，我们开发了一种双腔体外主动脉反搏器，其中有两个腔用于动力传输。六只狗植入了我们的双腔体外主动脉反搏器，其中两只之前已对其背阔肌进行了转化。血泵两端各有一个涤纶移植物，与胸主动脉进行端侧吻合且平行放置，以实现持续血流，将因血流淤滞和湍流导致的血栓形成降至最低。血泵由置于背阔肌下方的液压球囊驱动。使用同步脉冲电刺激器在舒张期刺激背阔肌收缩。根据升主动脉压力曲线计算反映心肌氧供需比的舒张压时间乘积与收缩期时间张力指数之比。当该装置启动时，4只背阔肌未转化的狗的这一比值持续增加了44%，而两只背阔肌已转化的狗增加了70%。使用美敦力心脏刺激器（型号SP1005）作为我们双腔体外主动脉反搏器的脉冲刺激器进行的初步慢性植入研究，在长达六天的时间里使主动脉舒张压平均升高了34毫米汞柱。我们的结果表明，随着该装置的进一步完善，由内源性骨骼肌驱动的长期完全植入式心脏辅助装置将是可行的。
