Atrial Tachycardia Arising From the Right Atrial Inferoseptum Masquerading as Common Atrial Flutter

Abstract

ost focal atrial tachycardias (ATs) originate from the right atrium (RA), the orifice of the pulmonary veins or the mitral annulus in the left atrium, 1-8 and radiofrequency (RF) catheter ablation has become an effective curative therapy. [1][2][3][4][5][6][7][8][9] In the RA, AT often originates along the crista terminalis, para-Hisian region, or from the inferoseptum, including the ostium of the coronary sinus (CS). [1][2][3][4][5][6][7] We describe 2 cases of AT arising from the RA inferoseptum. The remarkable characteristics of the tachycardia were that it masqueraded as isthmus-dependent, common atrial flutter (AFL). Case Reports Patient 1A 34-year-old woman with a 1-year history of incessant, exercise-induced palpitation attacks was admitted for evaluation of the tachycardia. A "saw-tooth" pattern in the inferior leads, and negative P-wave polarity in lead V6 and positive in lead V1 during the tachycardia with a cycle length of 210 ms mimicked common AFL (Fig 1A). After informed consent was obtained, catheter ablation was performed. At the beginning of the procedure, the patient had a normal sinus rhythm. The activation sequence across the cavo-tricuspid isthmus was in a clockwise direction during pacing from the CS ostium with a cycle length of 600 ms. The tachycardia could not be induced by programmed atrial stimuli. However, it could be induced by isoproterenol infusion, with a warm-up and cool-down phenomena, suggesting that the mechanism of this AT was automaticity. Activation mapping demonstrated a counterclockwise activation sequence around the tricuspid annulus during the tachycardia ( Fig 1B). The earliest atrial activation was found at a site near the CS ostium. The ablation catheter became stabilized at that site after clockwise torquing the catheter against the RA inferoseptum, away from the CS ostium. The local electrograms at that site exhibited double potentials, and a small, first potential preceded the atrial potential recorded at the CS ostium by 41 ms (Fig 2A). The tachycardia was eliminated by a single application of RF energy at that site. In the right anterior oblique view, the successful ablation site was posterior to the superior rim of the CS ostium, and corresponded to the Eustachian ridge (ER) (Fig 2B). The P-wave morphology and polarity during pacing from the successful ablation site were almost identical to those of the clinical tachycardia. During the tachycardia, a counterclockwise activation sequence was observed around the tricuspid annulus. However, during pacing from the ablation site with a longer cycle length of 600 ms after the ablation, the activation sequence across the isthmus was in the clockwise direction (Fig 2C). The patient was discharged without the need for medications and has done well with no AT recurrence during a 2-year follow-up period. Patient 2A 75-year-old man presented with a 2-year history of recurrent episodes of palpitation attacks. From the electrocardiographic findings recorded during the palpitations, he was diagnosed with common AFL. An intrav...

Swallowing‐Induced Atrial Tachyarrhythmias: Prevalence, Characteristics, and the Results of the Radiofrequency Catheter Ablation

“…Radiofrequency catheter ablation (RFCA) has been developed as a curative treatment for supraventricular tachyarrhythmias. [36][37][38][39] Recently, several cases of the swallowing-induced tachyarrhythmias have been reported. 33,34 We also reported the utility of the noncontact mapping system for ablating swallowing-induced arrhythmias in two cases.…”

“…Radiofrequency catheter ablation (RFCA) has been developed as a curative treatment for supraventricular tachyarrhythmias 36‐39 . Recently, several cases of the swallowing‐induced tachyarrhythmias have been reported 33,34 .…”

Focal atrial tachycardia arising from the cavotricuspid isthmus with saw-tooth morphology on the surface ECG: electrocardiographic and electrophysiologic characteristics

“…Balbato et al described that typical AFL ECG was a good predictor of CTI-dependent AFL, but in about 10% of typical AFL ECG, a non-CTI AFL was identified [8,9]. Waldo and Okumura et al described that the surface ECG of atrial flutter was dependent on the activation sequence of the LA [10].…”