Comparative Anatomy of Aortic and Mitral Valves in Human, Ovine, Canine and Swine Hearts

Abstract

Introduction: Pathologies such as ischemic mitral regurgitation reportedly result from a variety of factors including annular dilatation, left ventricular remodeling, papillary muscle position, and atrial factors. Additionally, the anatomical relationship of the mitral (MV) and aortic valves (AV) has led to investigations into the coupled kinetics of these valves in both normal and pathological states. Studies investigating these topics have utilized both human subjects as well as swine, ovine, and canine models. It can be difficult to compare data across such studies, due to specific anatomical differences. Hypotheses: Comparative anatomical analyses of animal models with human anatomy will better elucidate swine, canine and ovine research investigating ischemic mitral regurgitation. Methods: Human (n = 8), canine (n = 10), swine (n = 10), and ovine (n = 10) perfusion fixed hearts were measured using a Microscribe® 3D digitizing arm (3DX, Immersion Corp., San Jose, CA) while suspended from the ascending aorta within a rigid support structure. Four points were digitized on the mitral annulus, and six points were digitized on the aortic valve surrounding the cusps. Finally, the center of each valve and the most apical point within the left ventricle (LVA) were digitized. 3D distances between these points were calculated and analyzed statistically (ANOVA with Bonferroni correction). Results and Conclusions: Significant differences were not observed between the ovine, canine, or swine hearts in any of the dimensions assessed, but were observed between animal and human hearts (Table 1). The ovine mitral annular dimensions most closely resembled those of the human heart, although all models were significantly smaller in right/left diameters. The LV inflow and outflow dimensions, as measured from the MV and AV to the LVA, also demonstrated important anatomical differences between models. Namely, the canine hearts had significantly shorter LV inflow and outflow tracts compared to human hearts. The swine and ovine LV inflow and outflow tracts were similar in size, but smaller than those in the human hearts examined. Human AV diameters were greater than the animal species, but most closely resemble the swine AV diameters.