MUSCLE-POWERED AND PNEUMATIC-POWERED COUNTERPULSATING LVADS - A PILOT-STUDY

There is a worldwide interest in supporting the failing heart with a s keletal muscle by either wrapping it around the natural heart (dynamic cardiomyoplasty) or by constructing a skeletal muscle ventricle (SMV) used for counterpulsation. Conventional cardiomyoplasty in many clini cs carries an operative mortality rate of 15-20% partly because it req uires 6 weeks to train the muscle to contract continually. A flexible, pear-shaped blood pump with an inflatable air chamber was designed an d made around which a muscle can be wrapped. The advantage of our desi gn is that it can also be driven by pneumatic power, immediately suppo rting the circulation of a seriously ill patient while that patient is still on the operating table. After a period of time to allow for rev ascularization and the subsequent training of the muscle, the external pneumatic power can be gradually discontinued. Then the assisted pati ent becomes tether-free. If, at any time, the muscle power fails, the pneumatic-powered mechanism can be reactivated. In the preferred appro ach, the blood pump is connected to the aorta for diastolic counterpul sation. A muscle can either be wrapped around the blood pump directly, or around one of two separate muscle pouches connected to the blood p ump. To facilitate surgery, a large pouch is inserted under the muscul us latissimus dorsi, which is connected to a blood pump. When stimulat ed, the muscle will contract over the pouch compressing it and providi ng power to the blood pump. If it is found that the pressure generated in the pouch cannot meet the aortic blood pressure, it can be augment ed by using a pressure amplifier. An amplifier has been designed and c onstructed that can be incorporated into the pouch under the musculus latissimus dorsi. Once again. an external pneumatic power source could be used to drive this system while the muscle is being trained. We ca n make our pouches and pumps available to surgeons for experimental wo rk if they are willing to test them.