Electroanatomic Substrate of Idiopathic Left Ventricular Tachycardia

Abstract

Background-An abnormal potential (retroPP) from the left posterior Purkinje network has been demonstrated during sinus rhythm (SR) in some patients with idiopathic left ventricular tachycardia (ILVT). We hypothesized that this potential can specifically be identified and be a critical substrate for ILVT. Methods and Results-In 9 patients with ILVT and 6 control patients who underwent mapping of the left ventricle during SR using 3-dimensional electroanatomic mapping, an area with retroPP was found within the posterior Purkinje fiber network only in patients with ILVT. The earliest and latest retroPP was 185.4Ϯ57.4 and 465.2Ϯ37.3 ms after Purkinje potential; in the other patient with ILVT, an entire left ventricle mapping demonstrated a slow conduction area and passive retrograde activation along the posterior fascicle during ILVT. ILVT was noninducible in 3 patients after SR mapping. Diastolic potentials critical for ILVT during ILVT coincided with the earliest retroPP during SR in 7 patients. Mechanical termination of ILVT occurred in 5 patients. A single radiofrequency pulse was applied at the site with mechanical translation in 5 patients and the site with diastolic potential in 2 patients, and 3 radiofrequency pulses were delivered to the site with the earliest retroPP in the other 3 patients without inducible ILVT after SR mapping. No ILVT was inducible during control stimulation, and none recurred during follow-up of 9.1Ϯ5.1 months. Conclusion-In patients with ILVT, abnormal retroPP within the posterior Purkinje fiber network is a common finding.The earliest retroPP critical for ILVT substrate can be used for guiding successful ablation.

Pleomorphic ventricular tachycardia originating from Purkinje fiber network of left anterior fascicle

“…The left posterior fascicular Purkinje fiber-related reentrant VT is one of the most popular idiopathic VTs [1][2][3][4][5] . This VT is verapamil-sensitive and its QRS morphology is a RBBB configuration with left axis deviation.…”

“…Ouyang et al has reported that the earliest diastolic potential during the sinus rhythm detected around the left posterior fascicle can be substrate for idiopathic left ventricular tachycardia with a RBBB configuration and left-axis deviation 5 . They called that potential as retro PP, because these abnormal potentials may represent a retrograde Purkinje activation with slow conduction over a Purkinje-Purkinje or Purkinjeventricular-Purkinje connection attributable to unidirectional block 5 .…”

“…3C). Induction of VT converted the delayed potential 5 to the dp, and the morphology of QRS complex was altered in accordance with the change in the dp-V interval (Figs. 3A and 3B).…”

“…Idiopathic ventricular tachycardia (VT) with a right bundle branch block (RBBB) and left-axis deviation originating from the area of left posterior fascicle has been wellknown [1][2][3][4][5] . In rare instances, idiopathic left anterior fascicular VT has also been demonstrated 6 .…”

“…In rare instances, idiopathic left anterior fascicular VT has also been demonstrated 6 . Both VTs are verapamil-sensitive, and ablation of the diastolic potential representing the Purkinje potential has been effective in eliminating the VTs [3][4][5][6][7][8] . In the present case report, a patient with recurrent syncope and palpitation demonstrated pleomorphic VTs 9 originating from the Purkinje fiber network of left anterior fascicle, in which the critical diastolic potentials and delayed potentials were identified during the VTs and sinus rhythm.…”