Papillary muscles: morphological differences and their clinical correlations

The complex architecture of the papillary muscles (PMs) of the ventricles plays a crucial role in cardiac function and pathology. This comparative study aimed to examine the differences in PMs morphology between the right and left ventricles, focusing on their number, location, and shape. A total of 38 grossly normal hearts from donated bodies were dissected, and the number, location, and shape of PMs in both ventricles were observed. In this study, the left ventricle predominantly exhibited a single PM with 71.05% on the sternocostal surface and 57.89% on the diaphragmatic surface. The right ventricle showed a higher prevalence of single PM, at 89.47% on the sternocostal surface and 63.16% on the diaphragmatic surface. Broad-based shape of the PM emerged as the predominant variant, constituting 55.26% and 44.73% on the sternocostal and diaphragmatic surfaces of the left ventricle, respectively. In contrast, conical-shaped PM predominated in the right ventricle. Unique findings included "H" and "b" shaped muscles, conjoint PMs were observed exclusively in the left ventricle, and small papillary projections with direct tendinous cord attachment in the right ventricle. A distinct webbed shaped configuration of PM was exclusively observed in the right ventricle in only one specimen. No significant difference (P=0.84) was noted in muscle bellies between ventricular surfaces. This study emphasizes the complexity and variability in PM morphology, highlighting the importance of a thorough understanding of these structures for cardiothoracic surgeons, radiologists, and cardiologists to enhance interventional techniques.