Comparison of coronary sinus morphology in patients with and without atrioventricular nodal reentrant tachycardia by intracardiac echocardiography.

INTRODUCTION: Dual AV nodal physiology is the electrophysiologic substrate for AV nodal reentrant tachycardia (AVNRT), but the anatomic basis for this arrhythmia remains to be elucidated. Atrial flutter (AFL) has been shown to be more frequently inducible in patients with AVNRT.

METHODS AND RESULTS: A 3.2-French, 20-MHz intracardiac ultrasound (ICUS) catheter was introduced into the coronary sinus (CS), and two-dimensional ICUS images were recorded during transducer pullback in 21 patients with AVNRT and 18 control patients. Three-dimensional reconstruction of the CS was created using the TomTec Imaging system. The area of the CS lumen at 15 mm within the CS ostium (os) was not significantly different in patients with and without AVNRT (54.4 +/- 34.7 mm2 vs 39.1 +/- 28.5 mm2). However, the area of the CS os was significantly larger in patients with AVNRT than in those without (112.1 +/- 60.9 mm2 vs 71.7 +/- 44.4 mm2, P < 0.05). Three-dimensional morphology of the CS os revealed flaring in patients with AVNRT, giving it a "windsock" appearance. Sustained AFL was induced in 10 of 21 patients with AVNRT, but in none of 18 control patients (P < 0.005).

CONCLUSION: The CS os was significantly wider in patients with AVNRT than in those without. These findings may have important implications for arrhythmia pathogenesis in AVNRT as well as AFL.