COUPLING OF SKELETAL-MUSCLE TO A PROSTHESIS FOR CIRCULATORY SUPPORT

A durable bond between the end of skeletal muscles and prosthetic stru ctures could, with appropriate linkage, allow circulatory support powe r by synchronous and/or sequential contraction of several in situ cond itioned muscles. Potential advantages relative to a myoplasty wrap inv olve 1) less traumatic dissection, 2) efficient linear force developme nt, 3) selectable contraction rate, 4) greater stroke work, 5) indepen dent control of muscle pre-load and end diastolic pressure, and 6) ind ependent control of duration of muscle tension and ejection time. Howe ver, no existing means of tissue-prosthetic bonding appears adequate. Practicality would demand that full tension bearing capacity by the bo nd take no longer than muscle conditioning. A prosthesis was developed to achieve those goals. As scaled for this study, it is made of 7,200 -7,800 unspun, unplaited, 22 to 26 pm diameter polyester fibers swaged into four taper needles for weaving through distal muscle. The other end is formed into a polyurethane sheathed kernmantel cord for distal fixation. Devices were implanted in six 3 to 4 kg rabbits (unilateral posterior tibial tendon replacement, random side selection with contra lateral dissection/closure controls), and their tensile strength was t ested at 30 days. All healed well; leg movements were normal after 1 w eek. Limbs were frozen at -70 degrees C between death and testing. Con trol failure occurred at 243 +/- 94 N and experimental at 163 +/- 44 N (p = 0.065, t-test); highest estimated requirement was 17.2 N. Interf ace strength was adequate by 30 days. Continued investigations, addres sing other questions, are warranted.