Characterisation of myocardial bridges in pigs: a comparative anatomical analysis with the human heart.

Abstract

Few studies have been conducted in pigs concerning the presence of myocardial bridges (MB) on the coronary arteries and their branches, and some of them have evaluated small samples. The objective of this study was to characterise MB in pigs of commercial breeds. One hundred and fifty eight hearts of pigs destined to the slaughterhouse with stunning method were studied. The coronary arteries were perfused with polyester resin (palatal 85% and styrene 15%) and then subjected to potassium hydroxide infusion to remove the subepicardial fat. Ninety three MB were found in 67 (42.4%) specimens, 43 (46%) of which were located on branches of the right coronary artery, 38 (41%) on branches of the left coronary artery and 12 (13%) on both vessels. The MB occurred in 26 (38.8%) females and 41 (61.2%) males, but the difference was not statistically significant (p = 0.23). Single MB were most common (70%), followed by the presence of 2 (21%) MB in different vessels. the subsinusal interventricular artery was the vascular structure with the largest number of MB (46.2%), with its middle third being the most compromised segment (79%). The mean length of the MB was 11.23 ± 5.67 mm and the thickness of the suprapontine myocardium was 1.13 ± 0.48 mm. The frequency, localisation, and length of the MB reported in pigs are consistent with the findings of the present study, whereas in humans the MB involve mainly the anterior interventricular artery and are longer.