Study of Anatomical Variations of Mitral Papillary Muscles and their Significance: A Cadaveric Study from Southern India

Abstract

introduction: Papillary Muscles (PaM) are the muscular components of the mitral apparatus and include a small portion of the wall of the Left Ventricle (LV). There are Anterolateral Papillary Muscles (ALPM) and Posteromedial Papillary Muscles (PMPM) that are usually single, though may be seen in groups or as accessory PaM. The mitral papillary muscle is usually conical in shape with a single base and single apex, though they may also be pyramidal, fan-shaped or broad-apexed which may influence the passage of blood flow. Various patterns like bifid-apexed, perforated or long PaM may also be present with variable length. Alterations in the left ventricular shape and size may lead to disturbances in the Mitral Valve (MV) function. A papillary muscle, like the MV complex is unique and differs in morphology from one individual with high variability. Due to above mentioned reasons, knowledge of variations of mitral papillary muscle is crucial. Aim: To study variations in the morphology of mitral PaM in terms of length, number, shape and pattern in adult human cadaveric hearts. Materials and Methods: A total of fifty adult heart specimens, without gross deformity, were taken from the Institute of Anatomy, Madras Medical College and studied by conventional dissection method. The presence of mitral PaM, their number, length, shape and pattern were studied. A data sheet was made using Microsoft excel software and the mean, percentages and mode of variables were calculated. Results: In the present study, it was found that the two mitral PaM, namely anterolateral and PMPM were present in all the specimens. PMPM had a mean length of 21.6±4 mm and were longer than ALPM that had a mean of 18.9±3.97 mm. PMPM (68%) were mostly present in groups and ranged between one and four whereas the ALPM was predominantly single (76%). Most AMPM (56%) and PMPM (60%) were cone shaped. A 40% of ALPM and 60% PMPM had single, undivided base with an undivided apex. Conclusion: Considerable variations in number, shape, pattern and length of the PaM observed in the present study correlated with the findings of most other studies done previously. The data obtained may be useful for radiologists and cardio-thoracic surgeons.