A Comparative Study of Number and Position of Papillary Muscles and Clinical Significance

Introduction: Papillary muscles are the conical muscle masses project into the cavity of ventricle and are inserted into the valve cusps by chordae tendinae.They prevent the cusps from being forced back into the atrium during ventricular contraction.Their number and positions are highly variable.An anomalous papillary muscle can act as an ectopic foci.Hence these variations should be assessed before any operative intervention on the valve.Present study aim to analyse these variations in detail.Materials and Methods: This is a descriptive observational study to analyse the variations in number and position of papillary muscles in ventricles of 100 adult human hearts ranging in age from 17 to 80 years obtained from autopsy specimens.The methodology used was the dissection method according to standard autopsy techniques.The data obtained were quantified as frequencies (in %).Results: Of the 100 hearts studied, the right ventricle consisted of the usual three groups of papillary muscles in 84% of hearts whereas the remaining 16% of hearts had only two groups (rudimentary SPMs).The left ventricle consisted of two groups of papillary muscles in 73% of hearts ; three groups in 23%; four groups in 4% and none of the hearts contained single papillary muscle.Regarding the positions, the right ventricle had APMs in anterobasal position, the PPMs in posterobasal position and SPMs was located close to ventricular septum and no extra group of papillary muscles were found.In left ventricle, 73% of hearts had APMs and PPMs in anterolateral and posteromedial positions respectively, whereas in 27% (23% and 4%) hearts, the extra group of papillary muscles (third group and fourth group) were interlinked to PPMs and was situated in posterolateral position.Conclusion: These findings suggest that the variations in number and positions of papillary muscles should be anticipated before any operative intervention on the valvular apparatus.