Disparity in Morphology of Papillary Muscles of the Mitral Valve Complex With Surgical Significance

Abstract

Background: The mitral valve apparatus, consisting of the mitral valve leaflets and commissures and subvalvular apparatus-papillary muscles and chordae tendinae; is one of the most complex and intricately designed structures present in the human body and therefore the understanding of anatomical variations of papillary muscles becomes important for surgical interventional procedures, in response to the increasing incidence of valvular heart defects. The aim of the cadaveric analysis was to identify the disparity in the morphometry of the papillary muscles of the mitral valve complex. Therefore this study was taken up with an effort to extend the concepts previously presented as well as to overcome deficiencies in the knowledge of gross architecture and positional nomenclature of the papillary muscles.Materials and methods: Fifty formalinized cadaveric hearts were the material for study. Papillary muscles of left ventricle were classified according to a system developed by Berdajs et al., (2005), by precisely measuring shapes lengths and widths. Results:The significant outcome of this study indicates that no two papillary muscles out of the 50 specimens had the same size, shape or position. All the hearts had two distinct groups of muscles -anterolateral and posteromedial. Specific analysis of each group revealed data regarding the muscles. In the antero-lateral group of the specimens, the maximum height and width of the muscles was 37.40mm and 17.06mm respectively and in the postero-lateral group, 33.86 and 26.90mm respectively. Conical shaped muscles were the most commonly found muscles owing to the minimum obstruction posed by them to blood flow.Implication: Better understanding of morphological variations can help cardiothoracic surgeons to customize surgical procedures according to the papillary muscle pattern of the individual patient.

Morphological variations and morphometry of the papillary muscles of the mitral valve – a cadaveric study

“…[3 -10] Therefore, rupture of a papillary muscle group, following infarction of the adjoining ventricular wall, will lead to heavy regurgitation as the half of the support of each leaflet is lost. [10] There is considerable variation in the morphology of papillary muscle. Victor and Nayak presented a classification of 100 cases of papillary muscles in self-explanatory figurative language as conical, mammillated, flat topped, grooved, wavy, stepped etc.…”

“…[3] Shape of the muscle influence the passage of blood flow. [8,10] Conical shape of muscles facilitate smooth cardiovascular physiology. [10] Chances of left ventricular outflow tract obstruction is higher in muscles with broad apex, increase in number and size.…”

“…[8,10] Conical shape of muscles facilitate smooth cardiovascular physiology. [10] Chances of left ventricular outflow tract obstruction is higher in muscles with broad apex, increase in number and size. [8,10] On the other hand, if there are only two papillary muscle in the ventricle, an ischemic event affecting one papillary muscle will lead to severe valve impairment than heart with multiple bellies.…”

“…[10] Chances of left ventricular outflow tract obstruction is higher in muscles with broad apex, increase in number and size. [8,10] On the other hand, if there are only two papillary muscle in the ventricle, an ischemic event affecting one papillary muscle will lead to severe valve impairment than heart with multiple bellies. [8] Morphological variation of papillary muscles has a tremendous effect on selection of homograft on replacement of valve with homograft.…”