Counterclockwise Atrial Flutter Research Articles

Hybrid pharmacologic and ablative therapy: a novel and effective approach for the management of atrial fibrillation.

Maintenance of sinus rhythm in patients with recurrent atrial fibrillation is often difficult to achieve with pharmacologic therapy. Complex catheter ablative procedures are being developed, but efficacy and safety issues remain to be clarified. We hypothesized that combined pharmacologic and simple ablative therapies in a targeted subset of patients will improve success in the treatment of atrial fibrillation. We identified 13 patients (mean age 61.5 +/- 16.2 years) with atrial fibrillation who converted to electrocardiographic atrial flutter during antiarrhythmic drug treatment. Surface ECG suggested "typical" atrial flutter in 11 patients and "atypical" atrial flutter in 2. Intracardiac mapping and entrainment studies revealed 9 patients had counterclockwise isthmus-dependent atrial flutter, and the remaining 4 had complex activation patterns, suggesting the presence of multiple wavefronts. All 9 patients with typical atrial flutter underwent successful ablation. None of the 4 patients with complex activation patterns had successful ablation. Patients were followed for recurrences of atrial arrhythmias via clinic visits, record review, and interviews. In patients who underwent successful ablation and continued on antiarrhythmic drugs, 88.9% remain in sinus rhythm after a mean follow-up of 14.3 +/- 6.9 months (range 1 to 28). In patients who experience conversion of atrial fibrillation to atrial flutter during antiarrhythmic drug treatment, ablation and continuation of pharmacologic therapy is a safe and effective means of achieving and maintaining sinus rhythm.

Three-dimensional mapping of the common atrial flutter circuit in the right atrium.

The full circuit of common atrial flutter using conventional methods of sequential or multielectrode activation mapping is not completely understood. We performed three-dimensional right atrial endocardial activation mapping during common counterclockwise atrial flutter in 17 patients (16 men, 1 woman; mean age, 53+/-11 years) by using the Cordis-Biosense EP Navigation system and assessed the distribution of estimated conduction velocities and double and fractionated potentials. ECG flutter wave morphologies were compared with activation patterns. Points (91+/-29) were sequentially acquired covering 88+/-11% of the flutter cycle length of 239+/-22 ms. A wide and variable posterior zone of double and fractionated potentials coincided with blocking and colliding wave fronts and formed the posterior limit of the circuit. A progressively widening septal (sep) wave front ascending from just beyond the coronary sinus ostium, passed cranially as a broad front anterior to the superior vena cava (SVC) in 14 patients, whereas fusion around the SVC formed the superior (sup) limb of the circuit in 3. Bounded anteriorly by the tricuspid valve, the wave front descended down the lateral (lat) aspect of the right atrium before completing the circuit in all cases through the inferior vena cava-tricuspid annulus isthmus. The estimated conduction velocity in the medial isthmus (0.6+/-0.3 m/s) was lower than in the other limbs of the circuit (sup=1+/-0.5 m/s, lat=1+/-0.5 m/s, sep=0.9+/-0.4 m/s, P=.05). Double and fractionated potentials were constant and more prevalent in the posterior right atrium. ECG flutter wave morphology did not correlate with three-dimensional activation maps. Interindividual variations occur in the right atrial circuit of common atrial flutter, with constant activation through the cavotricuspid isthmus. A variable zone of block forms the posterior limit. Fusion around the SVC can occur, and ascending medial septal activation does not follow a consistent pattern.

Electrophysiologic characteristics and radiofrequency catheter ablation in patients with clockwise atrial flutter.

Although the mechanism and radiofrequency catheter ablation of counterclockwise (typical) atrial flutter have been studied extensively, information about the electrocardiographic and electrophysiologic characteristics and effects of radiofrequency ablation in patients with clockwise atrial flutter is limited. Thirty consecutive patients with clinically documented paroxysmal clockwise atrial flutter were studied. Endocardial recordings and entrainment study using a "halo" catheter with 10 electrode pairs in the right atrium were performed. Radiofrequency energy was applied to the inferior vena cava-tricuspid annulus (IVC-TA) and/or coronary sinus ostium-tricuspid annulus (CSO-TA) isthmus to evaluate the effects of linear catheter ablation. Eighteen patients had both counterclockwise and clockwise atrial flutters, and 12 patients had only clockwise atrial flutter. Both forms of atrial flutter had similar flutter cycle lengths (232 +/- 30 vs 226 +/- 25 msec, P = 0.526) but reverse activation sequences. Right atrial pacing at a cycle length 20 msec shorter than the flutter cycle length from the CSO-TA isthmus, IVC-TA isthmus, and the area between the two isthmuses revealed concealed entrainment with stimulus-to-P wave intervals of 32 +/- 19, 95 +/- 14, and 50 +/- 17 msec (P = 0.022) in the counterclockwise form, and 110 +/- 12, 40 +/- 20, and 60 +/- 15 msec (P = 0.018) in the clockwise form. In clockwise atrial flutter, 20 patients with biphasic P waves in the inferior leads had the presumed exit site of slow conduction area located at the low posterolateral right atrium; 10 patients with positive P waves in the inferior leads had the presumed exit site located at the mid-high posterolateral right atrium. Among the 18 patients with both forms of atrial flutter, linear ablation lesions directed at the IVC-TA isthmus eliminated both forms of atrial flutter in 14 patients; in the remaining 4 patients, CSO-TA linear lesions eliminated the counterclockwise form and IVC-TA lesions eliminated the clockwise form. Among the 12 patients with the clockwise form only, CSO-TA linear lesions eliminated flutter in 2 and IVC-TA linear lesions eliminated flutter in 10 patients. Successful ablation was confirmed by creation of bidirectional conduction block in the IVC-TA and/or CSO-TA isthmus during pacing from the proximal coronary sinus and right posterolateral atrium sandwiching the linear lesions. During the follow-up period of 17 +/- 8 months, 2 patients had recurrence of clockwise atrial flutter, 1 patient had new onset of atypical atrial flutter, and 2 patients had new onset of atrial fibrillation. Counterclockwise and clockwise atrial flutters may have overlapping slow conduction areas with different exit sites. Radiofrequency catheter ablation using the linear method directed at the IVC-TA and CSO-TA isthmuses was feasible and effective in treating both forms of atrial flutter.

Electrocardiographic patterns and results of radiofrequency catheter ablation of clockwise type I atrial flutter.

Counterclockwise right atrial propagation is usually observed in common atrial flutter, but little is known regarding flutter with clockwise right atrial rotation. The aim of this study is to describe the ECG characteristics and results of catheter ablation of atrial flutter with clockwise right atrial rotation. Among the 38 patients with type I atrial flutter in this study population, right atrial impulse propagation was counterclockwise in 20 and clockwise in 8. In the remaining 10 patients, both clockwise and counterclockwise patterns were seen. Clinical and ECG parameters associated with clockwise flutter were compared to those of 28 cases of counterclockwise atrial flutter. Ablation was performed in 11 of 18 cases using a technique identical to that used for counterclockwise flutter. A classical "sawtooth" pattern of the flutter wave was observed in 28 of 28 counterclockwise and 14 of 18 clockwise flutter. A shorter plateau phase, a widening of the negative component of the F wave in the inferior leads, and a negative F wave in V1 were the most consistent findings in clockwise flutter. Coronary sinus recording always showed septal to lateral left atrial impulse propagation. Ablation was successful in 11 of 11 cases of clockwise flutter in whom this procedure was performed, with 9.5 +/- 11.6 radiofrequency pulses delivered between the tricuspid valve and the coronary sinus ostium (n = 5) or the inferior vena cava (n = 5), and in the proximal coronary sinus (n = 1). After a follow-up of 46.6 weeks, two recurrences of clockwise flutter were encountered, which were successfully treated with a second session. Contrary to commonly accepted concepts, clockwise rotation of atrial flutter is not an infrequent phenomenon and can mimic counterclockwise rotation. It can also be successfully ablated by radiofrequency pulses.