A Simulation-Based Comparison of Human, Porcine and Ovine Pulmonary Artery Hemodynamics. Evaluating the Suitability of Large Animal Models for Endopulmonary Device Evaluation from a Hemodynamics Point of View

In the field of cardiovascular device development, new devices such as heart valves, stents or pressure probes for long term heart failure monitoring are subject to animal trials to evaluate their safety and efficacy. For such applications, swine and sheep are the animal models of choice owed to their similarities to humans with regards to heart size, weight and ventricular kinetics. However, clinical aspects regarding the choice of animal model revolve mainly around anatomical similarities as well as the ability to induce the desired pathology. In the case of pulmonary artery pressure sensors, both swine and sheep appear to be suitable candidates for animal trials since both animals have been used for pre-clinical evaluation. Hemodynamic aspects however, although equally important for device performance, appear rather underrepresented in current research and it remains uncertain whether anatomical similarities between humans and animal model in the region of interest translate to hemodynamic similarities. To provide insight whether pulmonary artery hemodynamics in large animal models are indeed comparable to those in humans, this work presents a computational fluid dynamics-based study on pulmonary artery hemodynamics for humans, swine and sheep. A total of 28 human, 41 porcine and 14 ovine transient simulations of pulmonary artery hemodynamics were performed based on subject-specific geometries reconstructed from computed tomography data. The distributions of wall shear stress (WSS) and oscillatory shear index (OSI) within the cohorts were then compared to assess hemodynamic similarity. Distributions of time averaged WSS were found to be similar between humans and sheep (median 1.2 vs. 1.5 Pa, interquartile range (IQR) 0.8 Pa vs. 0.6 Pa, Wilcoxon rank sum test p = 0.42) but were significantly different for swine (median 1.7, IQR 0.5, p < 0.05), whereas OSI was significantly different for sheep and swine (0.17 ± 0.04 vs. 0.14 ± 0.03 and 0.09 ± 0.02). between sheep and humans. In summary, pulmonary artery vessel wall stresses of both animal models appear broadly similar to humans, however, sheep seem to have a notable edge over swine in our study.