Surgery – Cardiac augmentation
Patent
1997-03-05
1999-03-30
Kamm, William E.
Surgery
Cardiac augmentation
A61N 1362
Patent
active
058881867
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention is related to medical devices. More specifically, the present invention is related to a device for converting muscle power into alternative forms of body work.
BACKGROUND OF THE INVENTION
The idea of using endogenous skeletal muscle as an energy source for cardiac assistance is not new. Many investigators have demonstrated that untrained skeletal muscle can provide circulatory support for short periods of time (minutes to hours). However, early studies were plagued by rapid muscle fatigue which discouraged the use of skeletal muscle as a long-term energy source for biomechanical assistance. This ultimately prompted researchers to explore the possibility of conditioning skeletal muscle via chronic electrical stimulation.
The ultimate objective of chronic myostimulation is to transform muscle to a fatigue-resistant state so that it performs much like the myocardium, which is an oxidative muscle capable of continuously pumping blood. Both cardiac and skeletal muscle contain contractile proteins which transform chemical energy into mechanical work, but skeletal muscle comprises several types of muscle cells with different physiologic and metabolic characteristics. These contractile fibers may be either glycolytic (fatigue-susceptible) or oxidative (fatigue-resistant). Slow-twitch muscle is generally oxidative, while more powerful fast-twitch muscle can be either glycolytic or oxidative. In order to utilize skeletal muscle for long-term circulatory assist, a conditioning scheme is needed to convert these fibers from glycolytic to oxidative metabolism.
The feasibility of converting fast-twitch muscle fibers to fatigue-resistant slow-twitch fibers was demonstrated by Salmons and Sreter in the mid-70s. (Salmons, S., and Sreter, F. Significance of impulse activity in the transformation of skeletal muscle type. Nature, vol. 263, 30-34, 1976). Since then, interest in skeletal muscle conditioning has increased and has become a major subject of current studies. (Sreter, F., Pinter, K., Jolesz, F., and Mabuchi, K., Fast to slow transformation of fast muscles in response to long-term phasic stimulation. Experimental Neurology, vol. 75, 95-102, 1982; Macoviak, J., Stephenson, L., Armenti, F., Kelly, A., Alavi, A., Mackler, T., Cox, J., Palatianos, G., and Edmunds, L., Electrical conditioning of in situ skeletal muscle for replacement of myocardium. J. Surgical Research, vol. 32, 429-439, 1982). Recently, both Frey and Dewar have shown that a short train or "burst" of pulses is effective in producing a sustained contraction with complete conversion of skeletal muscle to fatigue-resistant fibers. (Frey, M., Thoma, H., Gruber, H., Stohr, H., Huber, L., Havel, M., and Steiner, E. The chronically stimulated muscle as an energy source for artificial organs. Eur. Surgical Research, vol. 16, 232-237, 1984; Dewar, M., and Chiu, R. Cardiomyoplasty and the pulse-train stimulator. Biomechanical Cardiac Assist, Futura Publ. Co., 43-58, 1986).
This knowledge has led to a myriad of new techniques designed to utilize the transposition of conditioned contractile tissue. Applications include cardiomyoplasty, diastolic counterpulsation, and using the muscle as an energy source to drive cardiac assist devices. To date, most attempts to harvest this new power source have involved wrapping a muscle flap around the heart, aorta or prosthetic conduit, or shaping the muscle into a neo-ventricle. (Magovern, G., Park, S., Kao, R., Christlieb, I., and Magovern, Jr., G. Dynamic cardiomyoplasty in patients. J. Heart Transplantation, vol. 9, 258-263, 1990; Pattison, C., Cumming, D., Williamson, A., Clayton-Jones, D., Dunn, M., Goldspink, G., and Yacoub, M. Aortic counterpulsation for up to 28 days with autologous latissimus dorsi in sheep. J. Thoracic Cardiovascular Surgery, vol. 102, 766-773, 1991; Mannion, J., Hammond, R., and Stephenson, L. Hydraulic pouches of canine latissimus dorsi; potential for left ventricular assistance. J. Thoracic Cardiovascular Surgery, vol. 91, 534-544, 1986; Hammond, R., B
REFERENCES:
patent: 4453537 (1984-06-01), Spitzer
patent: 5098369 (1992-03-01), Hgilman et al.
Magovern James A.
Trumble Dennis R.
Allegheny-Singer Research Institute
Kamm William E.
Schwartz Ansel M.
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