Objectives: To perform intravascular imaging of atherosclerotic human coronary conduits in an animal model under conditions of flow and cardiac motion that approximate those encountered in vivo.
Background: Given the lack of animal models of vulnerable plaque, a model which would allow imaging of human disease and simulate coronary motion and blood flow could advance the development of emerging technologies to detect vulnerable plaques.
Methods: Human coronary segments from adult cadaver hearts were prepared as xenografts. In anesthetized Yorkshire pigs (45-50 kg) the chest was opened and the exposed aorta and right atrium were cannulated and attached in an end-to-end fashion to the human coronary xenograft, forming an aorto-atrial conduit. The xenograft was fixed to the anterior wall of the heart to simulate motion. Angiography and intravascular ultrasound (IVUS) of each graft were performed.
Results: Twelve human coronary grafts (10 from right coronary segments) were prepared and implanted successfully in seven animals. All animals tolerated the procedure. The average graft length was 39 +/- 2.3 mm. Blood flow rates distal to the graft were >100 ml/min in nine grafts. IVUS was performed in all 12 grafts and documented expansion of arterial (6.9%) and luminal (9.3%) dimensions during the cardiac cycle (P < 0.001 for both). There was a wide range of coronary atherosclerotic pathology within the grafts, including intimal thickening, fibrocalcific plaque, and deep lipid pools.
Conclusion: This human-to-porcine coronary xenograft model allows intravascular imaging of human coronary pathology under conditions of blood flow and motion, and may be used to develop technologies aimed at identifying high-risk plaques.