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BACKGROUND: Mitral valve chordae tendineae (CTs) are filaments of connective tissue that attach the mitral valves to the papillary muscles, which contract and cause tension on these chordae, so as not to allow separation of the valves during left ventricular systoles. The morphological particularities of CTs not only facilitate understanding of the genesis of mitral valve diseases, but also provide the basis for improvement of surgical techniques.
OBJECTIVE: To evaluate some morphological aspects of mitral valve CTs and papillary muscles, including number, distribution, type and macroscopic texture.
MATERIAL AND METHODS: An anatomical descriptive study on mitral valve CTs and papillary muscles was conducted on 27 hearts from human fetuses. The CTs were dissected via a longitudinal incision adjacent to the interventricular septum, and were viewed using a binocular stereoscopic microscope and documented via photographs. The following variables were analyzed: number and anatomical distribution of papillary muscles, number of heads per group of papillary muscles and number of CTs per muscle head. The CTs were classified in accordance with the methodology proposed by Lam (1970) and Gunnal et al. (2015).
RESULT: In 27 mitral valves, a total of 827 CTs was found, and “true chorda” was the predominant type of chorda. Approximately 717 CTs originated from the 497 muscle heads. These chordae and muscle heads were shared approximately equally among the papillary muscle groups, with similar chorda/head proportions. The number of CTs per head in the papillary muscle groups ranged from 0 to 6 chordae/head. There were 663 chordae with tendinous macroscopic texture and 84 with simultaneously tendinous and membranous texture.
CONCLUSION: Mitral valve CTs were predominantly of true type, with similar distributions among papillary muscle groups; and the false chordae that were found were more commonly fixed in the posterior papillary muscle group. The CTs generally originated in the apexes of the papillary muscle groups, with variations in the numbers of muscle heads and the numbers of chordae per head. The main macroscopic texture of the CTs was tendinous, complemented by occurrences of chordae with simultaneously tendinous and membranous texture.