EFFECTS OF DIMINISHED PULSATILE PERFUSION ON THE MECHANICAL PROPERTIES AND VASO-RESPONSE OF BOVINE LEFT EXTERNAL CAROTID ARTERY

The purpose of this work was to test the effects of diminished pulse on the mechanical properties and vasoresponse of bovine arteries. A segment was harvested at the time of implant of a continuous flow ventricular assist device. The goal was to maintain pump flow ∼ 50% of cardiac output. Another segment was removed at necropsy (after 30 days). The vessels were implanted into an ex-vivo perfusion system. Compliance was assessed by measuring external diameter change over a pressure pulse (P = 120/80 mmHg). The vessels were then tested to failure in a tensile testing device. Young's modulus, yield strength, and ultimate strength were derived from the data. The results of the work do not indicate a statistically significant change in vasoresponse or mechanical properties between arteries removed at baseline and at necropsy from the pump-implanted animals. However, the data suggests several trends occurring in the pump-implanted: the compliance (C) decreases (p < 0.25) the ultimate strength (US) of the tissue increases (p < 0.18) and the % constriction increases (p < 0.25). Statistical comparisons were also made between controls (n=2) and the implanted cows (n=7) at necropsy. The C in the controls is greater than in the implants (p < 0.06) The US of the arteries taken from the implanted cows is significantly greater than the sham controls at necropsy (p < 0.05). Further research i s required to verify if these observed trends are indeed significant.