Original articles Anatomic study of the tricuspid valve in children L.-R. Gerola, N. Wafae, M.-C. Vieira, Y. Juliano, R. Smith and J.-C. Prates Department of Morphology of the Federal University of São Paulo, Brasil Received September 09, 1999 / Accepted in final form March 03, 2001 Key words: Tricuspid - Heart valve - Child - Anatomic Correspondence to: L.-R. Gerola Abstract We performed an anatomic study of the right atrioventricular valve in children under one year of age using a conservative method of dissection of the heart valve. The main aspects studied were the number of cusps and their morphometric characteristics, such as the width of the base and the depth of the cusps. Other parameters studied were the number of papillary muscles, number of tendinous cords, and diameter of the fibrous ring and the last one were divided in three regions, anterior, posterior and septal for localization of cusps. Our results showed that the number of cusps varied from two to four. Three cusps was the commonest finding and the fourth cusp, if present, was classified as anterolateral in location. The anterior and septal cusps had bases bigger than those of the posterior and anterolateral cusps the septal cusp was deeper than the others and the number of tendinous cords was greater for the anterior and septal cusps than for the posterior and anterolateral cusps. In addition, the posterior region showed great variability in 35.7% it was occupied by undeveloped valve tissue and the posterior valve in these cases was located anteriorly. Anatomic studies of the human right atrioventricular valve have an extensive literature. Classic anatomic studies describe the right atrioventricular valve as tricuspid and form the starting point for other investigations. This classic description and some specialized works postulate three cusps in the right atrioventricular valve anterior, septal and posterior. On the other hand, Zeren et al [23] published a case of a quinticuspid right atrioventricular valve and Wafae et al [21] stated that this valve usually consists of four cusps. Additionally, many studies report commissural or accessory cusps [2, 4, 8, 11, 12, 13, 16, 19, 22]. All these studies relate to anatomical analysis in adults a specific study of the tricuspid valve in children is uncommon. Recently, there has been a great development of heart operations for the treatment of congenital heart disease and most of these operations have been done through the right atrium [1, 9]. Therefore, we believe that it is important to understand the anatomic characteristics of the right atrioventricular valve and its variations in children. In another study, our group established morphologic criteria for characterization of the cusps of the right atrioventricular valve [21 ], we have now applied these criteria to study the right atrioventricular valve in children, in order to determinate the main characteristics of the right atrioventricular valve in children under the age of one year. Material and methods Fifty hearts of children less than a year old with no macroscopic evidence of rheumatic and congenital lesions or other conditions that could cause alterations to the valve apparatus were selected. This material was provided by the Autopsy Service of Federal University of São Paulo with parental permission for autopsy and subsequent study. The hearts were from 23 male and 27 female subjects whose weight ranged from 2.1 kg to 10.0 kg (median 3.5, mean 4.1), only six children weighed more than 6 kg. The mean age was 1 month and the median 3.1 months. Dissection of the myocardium was carried out from the right atrioventricular fibrous ring to the origin of the papillary mm., preserving the integrity of the valve apparatus as a whole (Fig. 1).