Radiofrequency catheter ablation of nonsustained ventricular tachycardia and frequent ventricular premature contractions from left ventricular outflow tract

Objective To observe the results of radiofrequency catheter ablation for nonsustained ventricular tachycardia (NSuVT) and frequent premature ventricular contractions (PVCs) originating from left ventricular outflow tract,and also to discuss the indication for radiofrequency ablation. Methods Frequent severely symptomatic NSuVT and frequent PVCs in five patients were refractory to antiarrhythmic drugs.Radiofrequency catheter ablation was performed in these patients when the site of NSuVT and PVCs origin was identified with pace mapping technique. Results In all five patients,both NSuVT and PVCs shared the same electrocardiographic morphology,a pattern of atypical right bundle branch block with an inferior axis.From the site of left ventricular outflow tract just beneath the left coronary cusp of aortic valve,a local activation time 314 ms earlier than the onset of PVCs was recorded,and 12lead pace mapping demonstrated concordance with the NSuVT in 11(one patient) to 12 (four patients) ECG leads.NSuVT and PVCs were not inducible in all five patients after delivery of radiofrequency energy at this site.During a followup period of 136 months,NSuVT and PVCs recurred only in one patient,and the symptoms of the other four patients was singnificantly improved. Conclusion Radiofrequency catheter ablation is a safe and effective treatment for patients with nonsustained ventricular tachycardia and frequent premature ventricular contractions originating from left ventricular outflow tract.Appropriate selection of patients is very important.