Morphology of papillary muscles in the ventricles of heart - a review and meta-analysis

To review the morphology of papillary muscles in both the ventricles of heart.The articles were collected from databases such as MEDLINE etc. using Google as the search engine. Keywords used were papillary muscle morphology, papillary muscle dimensions, papillary muscle blood supply, papillary muscle histology, papillary muscle development and papillary muscle biomechanical properties. Studies were included if they assessed the aforesaid features of papillary muscles. Thirty-four studies were included in the review. Meta-analysis was done for number of right and left ventricular papillary muscles and dimensions of right ventricular papillary muscles. The data obtained from these studies was synthesized, pooled and all analyses were performed using R Statistical Software (v4.1.2; R Core Team 2021) with R package meta version 5.5-0.Marked difference existed between papillary muscles of right and left ventricles. In right ventricle, one anterior (76%), one posterior (38%) and one septal (30%) papillary muscle were most common. In left ventricle, one anterior (46%) and two posterior papillary muscles (26%) were most common. In both the ventricles, commonly observed gross appearances of papillary muscles were conical and flat-topped. Papillary muscles were lengthier in left ventricle than right ventricle. Anterior papillary muscle was 1.36cm long, 1.36cm broad and 0.64cm thick in right ventricle. It was the largest in both right and left ventricles.The morphology and measurements of papillary muscles vary significantly. Thorough knowledge of these variations will help surgeons to determine appropriate surgical repair procedures for the valve and subvalvular apparatus.