[Anatomical variations of Koch's triangle in patients with atrioventricular nodal reentrant tachycardia: usefulness of the left anterior oblique view].

OBJECTIVES

Several anatomical distances of Koch's triangle including the ablation site were measured and correlated with clinical features and slow pathway potentials in patients with atrioventricular nodal reentrant tachycardia to improve the avoidance of complete atrioventricular block.

METHODS

Sixty consecutive patients (24 males and 36 females, mean age 47 +/- 12 years) with successfully eliminated atrioventricular nodal reentrat tachycardia were studied. The distances between the His-bundle area and the base of the coronary sinus ostium (Dis HBE-CS) and the distances between the successful ablation site and the base of the CS ostium (Dis SP-CS) were measured in both right anterior oblique and left anterior oblique views, and used to define the dimensions of Koch's triangle. The relationship between the slow pathway potentials at the successful ablation site and anatomical distances was estimated.

RESULTS

The Dis HBE-CS in the right anterior oblique view was negatively correlated with patient age (r = -0.759, p < 0.001) and body mass index. In contrast, the Dis HBE-CS in the left anterior oblique view had only weak correlations with patient age and body mass index. The mechanism of the short Dis HBE-CS in the right anterior oblique view in elderly obese patients tended to change the shape of the tricuspid annulus from a circle to an ellipse, compressed by the ascending aorta and diaphragma. The Dis SP-CS in the right anterior oblique view associated with the low frequency potential (Haissaguerre's slow pathway potential) was longer than that associated with the high frequency potential (Jackman's slow pathway potential).

CONCLUSIONS

Elderly obese patients had shorter distances between the proximal His-bundle area and the base of the coronary sinus ostium in the right anterior oblique view. In contrast, the Dis HBE-CS in the left anterior oblique view was not so narrow. Therefore, slow pathway ablation can be performed safely without complicated complete atrioventricular block, using both the slow pathway potential guided approach and the anatomical guided approach, especially in the left anterior oblique view.