Electrocardiographic and electrophysiologic characteristics of anteroseptal, midseptal, and posteroseptal accessory pathways.
BACKGROUND
Approximately 30% of all accessory pathways (APs) are located in the septal area, and understanding the electrocardiographic and electrophysiologic of these APs is crucial for safe and effective ablation of these pathways.


OBJECTIVE
In this study, the electrocardiographic and electrophysiologic characteristics of anteroseptal, midseptal, and posteroseptal APs were investigated in detail to elucidate unique electrical properties of APs in each location.


METHODS
From April 2002 to October 2006, a total of 120 patients with a septal AP-mediated tachycardia were enrolled in the study. A detailed examination including electrocardiographic analysis and electrophysiologic study was performed in all patients.


RESULTS
A total of 120 patients, including 98 patients with posteroseptal APs, 14 patients with anteroseptal APs, and 8 patients with midseptal APs, were studied. The anteroseptal APs could be differentiated from the midseptal APs by the 2 or more positive delta waves in inferior leads, whereas there is significant overlap in electrocardiographic features of midseptal and posteroseptal APs. The mean tachycardia cycle length was significantly shorter in patients with midseptal AP compared with those with anteroseptal and posteroseptal APs (284 +/- 49 ms vs 342 +/- 46 ms vs 350 +/- 68 ms, P = .03). The AH interval during tachycardia was also shorter in patients with midseptal APs (149 +/- 16 ms vs 200 +/- 51 ms vs 168 +/- 48 ms, P = .04). The patients with posteroseptal AP had a significantly higher incidence of atrial fibrillation (35%) than those with either midseptal (12%) or anteroseptal (14%) APs (P = .04). The patients with posteroseptal APs also had a significantly shorter antegrade effective refractory period of the AP (276 +/- 54 ms) than those with either midseptal (313 +/- 71 ms) or anteroseptal (325 +/- 61) APs (P = .036).


CONCLUSIONS
Electrocardiographic analysis is a reliable method for differentiation of the anteroseptal from the midseptal APs, whereas the same is not true for the midseptal and posteroseptal APs. Midseptal APs were characterized by faster orthodromic tachycardia, whereas posteroseptal APs had a higher inducibility of atrial fibrillation.
Haghjoo
Majid
M
Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran. majid.haghjoo@gmail.com
Kharazi
Ali
A
Fazelifar
Amir Farjam
AF
Alizadeh
Abolfath
A
Emkanjoo
Zahra
Z
Sadr-Ameli
Mohammad Ali
MA
D000328:Adult; D001281:Atrial Fibrillation / Q000503:physiopathology*; D001283:Atrioventricular Node; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D004594:Electrophysiology; D005260:Female; D006325:Heart Atria / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006346:Heart Septum / Q000503:physiopathology*; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors; D013610:Tachycardia / Q000503:physiopathology*; D016896:Treatment Outcome