Anatomy and clinical importance of the triangle of Koch.

Abstract

The triangle of Koch occupies the atrial component of the muscular AV septum. The tissue of AV node and the “slow” and “fast” pathway of the AVNRT are incorporated in the triangle, which makes this area clinicaly important. The aim of this study was to present the morphology and clinical importance of the triangle of Koch. The study consists of two parts: basic and clinical. In the basic part, 100 human hearts fixed in formaldehyde were examined using common anatomical and histological methods. The numerical features of the triangle of Koch were measured in two different ways. In the clinical part of the study, the analysis was made on 100 patients who were tested and treated in the Electrophysiological laboratory of the Institute for Heart Diseases in Skopje. Using the data of patients weight and height, the numerical features of the triangle were calculated. The results obtained were statistically analysed. The first type of measuring, in the basic part of the study, gave the following mean values of the length of the sides of the triangle of Koch: side a (a1) 26.1 ± 3.1 mm, side b (b1) 20.8 ± 3.6 mm and side c (c1) 24.5 ± 2.5 mm. The mean value of the area of the triangle (P1) was 256.2 ± 67.6 mm2. According to the second type of measuring the following numerical features of the triangle were obtained: side a (a2) 20.8 ± 2.5 mm, side b (b2) 13.9 ± 2.8 mm and side c (c2) 19.8 ± 2.4 mm. The mean value of the area of the triangle (P2) was 139.47 ± 37.28 mm2. In the clinical part of the study, mean value of the length of the side a (a3) was 28.5 ± 2.7 mm, side b (b3) 12.9 ± 1.2 mm and side c (c3) 21.1 ± 2.7 mm. The mean value of the area of the triangle (P3) was 116.6 ± 12.3 mm2. Knowledge of the variations of numerical features of the triangle of Koch is fundamental for successful catheter placement in electrophysiological studies and radiofrequent catheter ablations.