Dimensions and muscular architecture of the triangle of Koch

The variability in the arrangement of the superficial atrial muscle fibers in the areas of the triangle of Koch may be one of the factors influencing the route for impulses entering the AV node. The purpose of this study was to present the dimensions of the triangle of Koch and to describe the arrangement of the subendocardial atrial muscle fibers that form the approaches to the AV node, in and around the area of the triangle of Koch. The examination was made on 50 human hearts got obtained after autopsies of patients older than 18 years, died from no cardiac reasons, and fixed in 10% formaldehyde. The dimensions of the triangle of Koch were measured using the caliper. For the analyzing of the arrangement of the subendocardial muscle fibers, the right atrium was divided into four areas and the atrial endocardium was carefully peeled. The mean value of the area of the triangle of Koch (P) was 261.65 +/- 52.30 mm2 (min 160.00; max 375.00), the length of side a, was 24.14 +/- 14.2.53 mm (min 18; max 29), side b, was 20.12 +/- 2.42 mm (min 15; max 25) and side c, was 25.80 +/- 2.83 mm (min 20; max 31). The analyzing of the arrangement of the subendocardial superficial muscle fibers showed that 36 of the specimens had approximately precise patterns of fiber orientation within the areas of the right atrium. Variations in the fiber orientation were observed in 14 specimens. The knowledge of the anatomic features, dimensions and the architecture of the subendocardial muscle fibers of the triangle of Koch is the essential for both successful investigation and interpretation of the electrophysiological basis of heart dysrithmic diseases.