Background and aim of the study: Advances in echocardiography have awoken new interest in the tricuspid valve, which otherwise has been largely ignored by cardiologists and surgeons. These advances demand a precise terminology for the description of the tricuspid valve's different anatomic structures in health and disease. While simple nomenclatures have been developed for the mitral valve, no such system has been described for the tricuspid valve.
Methods: In order to develop a tricuspid valve terminology similar to the existing mitral valve nomenclature, a study of 50 porcine hearts was conducted. The study was designed not as a strict anatomical description but rather as a search for common parameters between both valves. The findings were based on the traditional understanding that the tricuspid valve has three main leaflets and three papillary muscles. The leaflets were defined according to their heights (free edge to base) and their chordal insertions. The papillary muscles were grouped according to the distribution of their chords to a commissure and its contiguous main leaflets.
Results: In all hearts, three main leaflets were found: septal (S), anterior (A), and posterior (P), associated with a variable number of commissural leaflets (C). Three groups of papillary muscles could be identified: anteroseptal with a mean of 1.78 muscles (range: 1-4), anteroposterior with 1.08 muscles (range: 1-4), and posteroseptal with 2.42 muscles (range: 1-5). Each group was identified (counterclockwise) with the numerals 1 (anteroseptal), 2 (posteroseptal), and 3 (anteroposterior). Each half of the leaflets and their corresponding commissures were identified by the initial letter of their classic name (S, A, P, or C) and their supporting papillary muscle group (1, 2, or 3).
Conclusion: This system provides a method for reporting echocardiographic and surgical findings for the tricuspid valve. The system parallels previously described mitral valve nomenclature. This unified terminology should facilitate the precise recording of echocardiographic and surgical data.