Objective: The purpose of this study was to determine the proportions among the segments of the human tricuspid valve annulus. Methods: A descriptive autopsy study was made of 30 human hearts without fixation, within six hours of death, without congenital or acquired lesions and without tricuspid regurgitation. Tricuspid valve insufficiency was excluded by the infusion of pressurized water in the right ventricle with the pulmonary valve closed. Digital images of the tricuspid ring in its anatomical position and after flattening were analyzed by specific software. The mean measurements and ratios were compared in the two different situations. Results: The mean measurements of the perimeter, septal and antero-posterior segments of the tricuspid ring in the anatomical position were: 105 mm (± 12.7), 30.6 mm (± 3.7) and 74 mm (± 9.4), respectively. When flattened, the mean measurement of the perimeter was 117.5 mm (± 13.3) and the sizes of the septal, anterior and posterior segments were 32 mm (± 3.7), 46.3 mm (± 8.3) and 39.1 mm (± 8.5), respectively. The mean ratio between the antero-posterior and septal segments was 2.43 (± 0.212) in the anatomical position and when flattened it was 2.67 (± 0.304). Statistical differences were observed in the measurements of the perimeter (p<0.0001), septal segment (p=0.003) and antero-posterior segment (p<0.0001) in both situations. Statistical differences also occurred in the ratios between the antero-posterior and septal segments (p=0.0005). Conclusions: The proportion between the septal and antero-posterior segments of the normal human tricuspid valve is 1:2.43. Flattening the tricuspid ring to measure the segments, changes the values and the ratios between them.213262271Revuelta, J.M., (2003) The Forgotten Funcional Tricuspid Insufficiency: Is Valve Repair Necessary?, , http://www.ctsnet.org/sections/innovation/valvetechnology/articles/ article-9.html, In My Opnion Jun [acesso em 16 de junho de 2003]Disponível emFrater, R., Tricuspid insufficiency (2001) J Thorac Cardiovasc Surg, 122 (3), pp. 427-429King, R.M., Schaff, H.V., Danielson, G.K., Gersh, B.J., Orszulak, T.A., Piehler, J.M., Surgery for tricuspid regurgitation late after mitral valve replacement (1984) Circulation., 70 (3 PART2), pp. I193-7Waller, B.F., Howard, J., Fess, S., Pathology of tricuspid valve stenosis and pure tricuspid regurgitation - Part III (1995) Clin Cardiol, 18 (4), pp. 225-230Kirklin, J.W., Pacífico, A.D., Surgery for acquired valvular heart disease (1973) N Engl J Med, 288 (4), pp. 194-199Deloche, A., Guerinon, J., Fabiani, J.N., Morillo, F., Caramanian, M., Carpentier, A., Étude anatomique des valvupathies rhumatismales tricuspidiennes. Application à l'étude des différentes valvuloplasties (1973) Ann Chir Thorac Cardiovasc, 12 (4), pp. 343-349Silver, M.D., Lam, J.H., Ranganathan, N., Wigle, E.D., Morphology of the human tricuspid valve (1971) Circulation, 43 (3), pp. 333-348Jatene, F.B., Koike, M.K., Monteiro, R., Veronezi, S.C., Magalhães, M.H.G., Jatene, A.D., Avaliação anatômica da valva tricúspide (1992) Rev Bras Cir Cardiovasc, 7 (1), pp. 22-27Andrade, N.M.M., Tinois, E., Vieira, R.W., Braile, D.M., Petrucci Jr., O., Oliveira, P.P.M., Coeficientes de proporcionalidade nas valvas atrioventriculares: Estudo anatômico dos segmentos valvares em indivíduos normais (2005) Braz J Cardiovasc Surg, 20 (3), pp. 255-260Curti, H.J., Sanches, P.C., Carvalhal, S.S., Cardiac rigor mortis (1985) Arq Bras Cardiol, 45 (6), pp. 439-446Eckner, F.A.O., Brown, B.W., Overll, E., Glagov, S., Alteration of the gross dimensions of the heart and its structures by formalin fixation. A quantitative study (1969) Virchows Archiv Abt A Pathol Anat, 346, pp. 318-329Tei, C., Pilgrim, J.P., Shah, P.M., Ormistom, J.A., Wong, M., The tricuspid valve annulus: Study of size and motion in normal subjects and in patients with tricuspid regurgitation (1982) Circulation, 66 (3), pp. 665-671Ubago, J.L., Figueroa, A., Ochoteco, A., Colman, T., Duran, R.M., Duran, C.G., Analysis of the amount of tricuspid valve anular dilatation required to produce functional tricuspid regurgitation (1983) Am J Cardiol, 52 (1), pp. 155-158Hueb, A.C., (2000) Análise Comparativa Dos Anéis Valvares Atrioventriculares Esquerdo e Direito Na Cardiomiopatia Dilatada de Diferentes Etiologias: Um Estudo Anatômico, , [Tese de Doutorado]. São Paulo;Universidade de São PauloHueb, A.C., Jatene, F.B., Moreira, L.F.P., Pomerantzeff, P.M., Kallás, E., Oliveira, S.A., Ventricular remodeling and mitral valve modifications in dilated cardiomyopathy: New insights from anatomic study (2002) J Thorac Cardiovasc Surg, 124 (6), pp. 1216-1224McCarthy, P.M., Does the intertrigonal distance dilate? Never say never (2002) J Thorac Cardiovasc Surg, 124 (6), pp. 1078-1079Carpentier, A., Deloche, A., Hanania, G., Forman, J., Sellier, P., Piwnica, A., Surgical management of acquired tricuspid valve disease (1974) J Thorac Cardiovasc Surg, 67 (1), pp. 53-65Kay, J.H., Maselli-Campagna, G., Tsuji, K.K., Surgical treatment of tricuspid insufficiency (1965) Ann Surg, 162 (1), pp. 53-58De Vega, N.G., La anuloplastia selectiva, regulable y permanente (1972) Rev Esp Cardiol, 25 (6), pp. 555-556Carpentier, A., Deloche, A., Dauptain, J., Soyer, R., Bloundeau, P.H., Piwnica, A., A new reconstructive operation for correction of mitral and tricuspid insufficiency (1971) J Thorac Cardiovasc Surg, 61 (1), pp. 1-13Carvalho, R.G., Mulinari, L.A., Giublin, P.R., Mulasky, J.C., Silva Jr., A.Z., Lopes, L.R., Emprego do anel de Gregori na posição invertida para o tratamento da insuficiência tricúspide: Experiência inicial (1998) Rev Bras Cir Cardiovasc, 13 (2), pp. 152-157Braile, D.M., Ardito, R.V., Pinto, G.H., Santos, J.L.V., Zaiantchick, M., Souza, D.R.S., Plástica mitral (1990) Rev Bras Cir Cardiovasc, 2 (2), pp. 86-98McCarthy, J.F., Cosgrove III, D.M., Tricuspid valve repair with the Cosgrove-Edwards Annuloplasty System (1997) Ann Thorac Surg, 64 (1), pp. 267-268McCarthy, P.M., Bhudia, S.K., Rajeswaran, J., Hoercher, K.J., Lytle, B.W., Cosgrove, D.M., Tricuspid valve repair: Durability and risk factors for failure (2004) J Thorac Cardiovasc Surg, 127 (3), pp. 674-685Fukuda, S., Song, J.M., Gillinov, A.M., McCarthy, P.M., Daimon, M., Kongsaerepong, V., Tricuspid valve tethering predicts residual tricuspid regurgitation after tricuspid annuloplasty (2005) Circulation, 111 (8), pp. 975-979