VT from the Aortic Sinus of Valsalva
Abstract & Commentary
Synopsis: A significant proportion of patients with outflow tract tachycardia have initiation from a site reachable from the aortic sinus of Valsalva. Map-guided radiofrequency ablation can effectively eliminate these arrhythmias.
Source: Kanagaratnam L, et al. J Am Coll Cardiol. 2001;37:1408-1414.
Kanagaratnam and colleagues describe unusual electrophysiologic findings in a group of 12 patients with recurrent ventricular tachycardia (VT) arising from the left ventricular outflow tract who were referred to their laboratories for ablation.
The 12 patients described in this report comprised 18% of all patients who were referred for radiofrequency ablation for VT with a left bundle branch block morphology and inferior axis during the period of the study. At electrophysiologic study, pace mapping and activation mapping during ventricular tachycardia were performed first in the right ventricular outflow tract, the typical site of origin. If no successful ablation site was found, left ventricular outflow tract mapping was next performed. When the site of origin was still not identified, either epicardial mapping or supravalvular mapping in the region of the sinus of Valsalva was performed. When a paced QRS identical to the clinical VT was identified, radiofrequency ablation was then performed.
The study group included 7 women and 5 men with a mean age of 27 ± 10 years. Structural heart disease had been excluded in all patients. The ECG had a left bundle branch block pattern with small R waves in V1 and an early transition to a dominant R in V2 or V3. Isoproterenol and/or phenylephrine infusion was required for VT initiation in all patients. Mapping in the right ventricular outflow tract and in the left ventricular outflow tract below the aortic leaflets failed to show a perfect QRS match. Although early activation times could be found using epicardial mapping, mapping in the region of the aortic sinus of Valsalva showed the earliest local activation times and the best pace maps. However, once the appropriate site was identified, a single radiofrequency application effectively eliminated the arrhythmia. Follow-up showed that all 12 patients remained tachycardia free over a period of 8 ± 2.6 months. No complications from the procedures were noted.
Kanagaratnam and colleagues conclude that a significant proportion of patients with outflow tract tachycardia have initiation from a site reachable from the aortic sinus of Valsalva. Map guided radiofrequency ablation can effectively eliminate these arrhythmias.
Comment by John P. DiMarco, MD, PhD
Radiofrequency ablation has become the therapy of choice for highly symptomatic patients with normal hearts and several types of ventricular tachycardia. The most common type has a left bundle branch block morphology and an inferiorly directed axis. The second most common pattern of VT in patients with normal hearts has a right bundle branch block pattern with left axis deviation and arises from the inferior left ventricular septum. A small number of patients with VT with a morphology resembling left bundle branch block with an inferior axis have been reported in whom successful ablation from the right ventricular outflow tract has not been possible. Some of these patients have left ventricular outflow tract sites of origin but in other cases, ablation using standard techniques in that region have not been successful. Some authors have reported successful ablation of this form of VT with epicardial lesions placed either directly or using a branch of a small cardiac vein.
In this paper, Kanagaratnam et al show another approach for ablating VT in these patients. They have excellent success and eliminated tachycardia in all 12 patients by delivering energy in an aortic sinus of Valsalva.
Patients in this series were highly symptomatic and failed multiple attempts of therapy. Kanagaratnam et al were fortunate in that they did not have any complications related to their procedure. Ablation in or above in the area of the aortic valve entails a significant possibility for creating valvular damage, atrioventricular block by damaging the bundle of His which runs through this area, or coronary artery occlusion if energy is delivered in a coronary orifice. Any of these complications could be catastrophic. Therefore, despite the excellent results reported here, the procedure should be reserved for only extremely highly symptomatic patients in whom the risk is justified.
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