title: Atrial electrogram amplitude and efficacy of cavotricuspid isthmus ablation for atrial flutter.
abstract: Large atrial electrogram amplitudes recorded in the cavotricuspid isthmus (CTI) may reflect thick atrial musculature. For this reason, in patients with atrial flutter, the efficacy of an application of conventional radiofrequency energy may be related to the amplitude of the local atrial electrogram. In 100 consecutive patients (mean age 59 +/- 13 years) with atrial flutter, contiguous applications of radiofrequency energy were delivered in the CTI. The criterion for complete CTI block was the presence of widely split double potentials (>110 ms) along the entire ablation line during pacing from the coronary sinus and posterolateral right atrium. The atrial electrogram amplitude was measured before and after applications of radiofrequency energy at sites of gaps in the ablation line. Complete CTI block was achieved in 90 (90%) of the 100 patients. The mean atrial electrogram amplitudes at gap sites where an application of radiofrequency energy did and did not result in complete block were 0.36 +/- 0.42 and 0.67 +/- 0.62 mV, respectively (P < 0.01). The positive and negative predictive values (for complete block) of a >/=50% decrease in electrogram amplitude after an application of radiofrequency energy were 100% and 35%, respectively. The mean atrial electrogram amplitude is larger at CTI sites where complete isthmus block cannot be achieved with conventional radiofrequency energy. The efficacy of conventional radiofrequency ablation may be improved by identifying areas in the CTI where the voltage is relatively low.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ozaydin
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tada
authors.forename: Aman
authors.initials: A
authors.lastname: Chugh
authors.forename: Christoph
authors.initials: C
authors.lastname: Scharf
authors.forename: Steve W K
authors.initials: SW
authors.lastname: Lai
authors.forename: Frank
authors.initials: F
authors.lastname: Pelosi
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Knight
authors.forename: Fred
authors.initials: F
authors.lastname: Morady
authors.forename: Hakan
authors.initials: H
authors.lastname: Oral
mesh_terms: D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery*; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria; D006327:Heart Block / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged