Background: Some supraventricular tachycardias could be ablated from the non-coronary sinus of Valsalva (NSV). However, the characteristics of the NSV electrograms have not been clarified.
Methods and results: A quantitative analysis of the NSV electrograms was performed in 5 patients with tachycardias arising from near the atrioventricular node (AVN) and the His-bundle region, and in 20 control subjects. In another 7 control subjects, the NSV electrograms were compared with those recorded at the left and right sinus of Valsalva (LSV and RSV). The NSV electrograms during sinus rhythm had a larger atrial amplitude than ventricular amplitude, and the ratio of the atrial amplitude to the ventricular amplitude was usually >1, which was apparently different from the LSV and RSV electrograms. A tiny but distinct His-bundle deflection was sometimes recorded at the NSV during sinus rhythm while it was not during the tachycardia. The distance to the His-bundle region in the anteroseptal right atrium was shorter from the NSV than from the RSV or LSV.
Conclusions: The precise identification of the catheter position at the NSV is possible using the characteristics of the electrograms. Much attention should be paid during ablation to the NSV because of its vicinity to the AVN and His-bundle region.