Five month study of percutaneous heart valves in the systemic circulation of sheep using a novel model of aortic insufficiency.

AIMS: To study the 5 month performance of a balloon-expandable percutaneous heart valve (PHV) in the systemic circulation of animals.

METHODS AND

RESULTS

Moderate-to-severe (>/= grade 3) aortic insufficiency was created in 14 juvenile sheep using a bioptome device. A 23mm PHV was implanted distal to the left subclavian artery (1.78+/-0.18 cm2 area, 27+/-2 mmHg closing gradient). Valve performance was followed angiographically (baseline, 21 weeks) and echocardiographically (baseline, 6, 14, 21 weeks). Animals were euthanized at 21 weeks or at the first sign of valve dysfunction. Four animals died of acute procedural complications (aortic perforation, mitral valve damage, hemothorax, and sheath dissection of brachio-cephalic artery). One animal with a rotated PHV (secondary to aortic dissection) was euthanized at 6 weeks; 3 animals were euthanized at weeks 6 and 14 because of decreased leaflet mobility (normal PHV at autopsy, decreased mobility related to halothane-induced hypotension). Six animals with normal PHV function (1.68+/-0.12 cm2 area, 23+/-4mmHg closing gradient) were euthanized at 21 weeks; pathologic examination revealed no significant PHV abnormalities. Native aortic valve insufficiency was grade 2-4 at 21 weeks.

CONCLUSION

PHV function remains satisfactory to 21 weeks in the descending aorta. This animal model is valid for chronic study of PHV in the systemic circulation.