Large animal model of chronic pulmonary hypertension.

A large animal model is needed to study artificial lung attachment in a setting simulating chronic lung disease with significant pulmonary hypertension (PH). This study sought to create a sheep model that develops significant PH within 60 days with a low rate of mortality. Sephadex beads were injected in the pulmonary circulation of sheep every other day for 60 days at doses of 0.5, 0.75, and 1 g (n = 10, 10, 7). Mean pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac output were obtained every 2 weeks. In the 0.5, 0.75, and 1-g groups, 90, 70, and 14.3% of sheep completed the study, respectively, with the remainder experiencing heart failure. By the 60th day, pulmonary vascular resistance had increased (p < 0.01) from 0.89 +/- 0.3 to 3.2 +/- 0.9 mm Hg/(L/min) and from 0.9 +/- 0.3 to 4.3 +/- 3.2 mm Hg/(L/min) in the 0.5 and 0.75-g groups, respectively. Significant right ventricular hypertrophy was observed in the 0.75-g group but not in the 0.5-g group. Data from the 1-g group were insufficient for analysis due to high mortality. Thus, the 0.5 and 0.75-g groups generate significant PH, but the 0.75-g group is a better model of chronic PH in lung disease due to the development of right ventricular hypertrophy.