Comparative Analysis of Morphological and Morphometric Features of Human, Pig, Calf, and Sheep Aortic Valves: A Cross-sectional Study

Abstract

Introduction: The aortic valve plays a critical role in maintaining unidirectional blood flow from the left ventricle into the aorta, ensuring efficient circulation throughout the body. Comprising three cusps-the left coronary, right coronary, and non-coronary cusps-the intricate anatomy of the aortic valve is essential for its proper function. The scarcity of aortic valve homografts for transplantation has led to increased interest in studying readily available sources for suitable and durable xenografts. Aim: To compare the morphological and morphometric characteristics of the aortic valves in humans with those in pigs, calves, and sheep. Materials and Methods: The present cross-sectional study was conducted over a three-week period in July 2022. Aortic valves were collected from humans, pigs, calves, and sheep. Five human hearts were obtained from the Anatomy Department of Adichunchanagiri Institute of Medical Sciences, BG Nagar. Additionally, five hearts each from calves, pigs, and sheep were obtained from a nearby abattoir. The hearts were then fixed in a 10% formaldehyde solution for approximately 18 hours. All fat and muscle surrounding the aorta were removed, and the aorta with intact valves was dissected. An incision was made between the left coronary and non-coronary aortic cusps to measure the individual cusps. Morphological and morphometric measurements, including annulus diameter, cusp height, commissural distances, and length of the lunula, were taken using a vernier calliper. The obtained values were statistically compared using paired t-test. Results: The mean values of various measurements of human aortic valves were found to be similar to those of pig aortic valves. Both humans and pigs have three aortic cusps, namely the left, right, and non-coronary cusps. The mean diameter of the aortic annulus in humans was 2.18 cm, while in pigs it was 2.28 cm. The height of the left and right cusps in both human and pig aortic valves was approximately 1.6 cm, whereas the height of the non-coronary cusp was 1.64 cm in humans and 1.38 cm in pigs. The external inter-commissural distance of the left cusp was 2.48 cm, and that of the right cusp was 2.58 cm in both humans and pigs. The external inter-commissural distance of the non-coronary cusp was 2.4 cm in humans and 2.36 cm in pigs. The length of the lunula and internal inter-commissural length of the aortic cusps in humans were relatively similar to those in pigs. However, when compared to measurements in cows and sheep, significant variations were observed. Conclusion: The study findings provide valuable insights into the potential suitability of pig aortic valves for xenograft transplantation and their implications for cardiac surgical procedures.

Keywords

• cusps
• histology
• transplantation
• xenograft