The Electrophysiologic Characteristics And Radiofrequency Catheter Ablation Of Idiopathic Ventricular Arrhythmias Originating From The Papillary Muscles

Background Most of idiopathic left ventricular inflow tract ventriculartachycardia(VT) are the fascicles of left bundle branch VT which can besuccessfully cured by catheter ablation. Recently，some abroad literatures reportthe ablation of the VT or premature ventricular contractions(PVCs） originatingfrom the papillary muscles in left or right ventricle. It’s difficult and challengeeven unsuccessful to ablate these Ventricular arrhythmias (VA) because the baseof the papillary muscles is large，the anatomy of the papillary muscles is varietal，and it’s very difficult to locate the ablation catheter at the target when mappingand ablating. The recurrent rate is high to60%. Recently，there is rare internalreport of these VAs.Object To report the electrocardiographic and electrophysiological characteristics and the results of radiofrequency catheter ablation of idiopathicVAs originating from the papillary muscles (PAM) in the left or right ventricle.Methods Thirty-four sequential patients(27men, aged from4to66years)underwent catheter ablation of idiopathic left ventricular inflow tract VT or PVCsin Shenyang Northern Hospital.2of them are recurrent patients. We reportadditionally1patient with PVCs arising from the Septal PAM of the rightventricle. There are no evidence of structural heart disease all judged by sternite,surface electrocardiogram(ECG), echocardiogram and part of then judged byventriculography and coronary arteriongraphy. Eight patients (7men, aged from4to66years) underwent catheter ablation of idiopathic VA originating from thepapillary muscles judged by electrophysiological study and ventriculography. Sixpatients had ventricular tachycardia (VT) and2patients had frequent prematureventricular contractions (PVCs).Results In the8patients, there were6patients whose VA originated from theposterior PAM of the left ventricle, and there were2patients whose VAoriginated sepatately from the anterior PAM of the left ventricle and the septalPAM of the right ventricle. Compared to idiopathic left ventricular fascicular VT,the VA originating from the posterior PAM of the left ventricle had wider QRSduration (145±21ms vs.115±11ms, P＜0.05). Catheter ablation of these VA wasmore difficult. In4recurrent patients whose initial ablation was performed byusing nonirrigated4mm-tip catheter, the VAs were eventually eliminated byusing irrigated-tip catheter in3patients and nonirrigated4mm-tip catheter in1four-year-old boy. In the other4patients, the irrigated-tip catheter was directlyused at the first procedure and acute success was obtained in all the4patients.During follow-up, the VAs recurred in only1of the4patients. No complicationshave been found in the patients. Conclusion Some VA might originate from the PAMs, and these VA had somespecific characteristics in surface ECG. Radiofrequency catheter ablation of theseVA was more difficult in almost all the cases, and the recurrence rate was alsohigher. Catheter ablation using saline irrigated-tip catheter might increase thesuccess rate.