Atrial Flutter Mapping and Ablation I

Endocardial mapping has led to a detailed knowledge of reentry mechanisms in atrial flutter. Multipolar and deflecting tip catheters allow recording local electrograms from multiple areas of the right atrium, and from the coronary sinus. In common flutter, with the typical "sawtooth" pattern, there is circular activation of the right atrium in a "counterclockwise" direction, descending in the anterior and lateral walls, and ascending in the septum and posterior wall. Superior and inferior vena cava, linked by a "line" of functional block in the posterolateral wall, make the central obstacle for circular activation. The cranial and caudal turning points are the atrial "roof," and the isthmus between the inferior vena cava and the tricuspid valve. Complex conduction patterns, probably including slow conduction are detectable in the low septal area, around the coronary sinus. Atypical flutter, without the sharp negative deflections of common flutter, sometimes shows circular activation in the right atrium, rotating in the opposite direction of common flutter (clockwise). Other atypical flutters show no circular right atrial activation, and only partial data from coronary sinus activation, combined with the response to atrial stimulation (entrainment) allow the diagnosis of left atrial reentry, without a precise delimitation of the circuits. In patients having undergone cardiac surgery, atypical flutter may be based on reentry around surgical scars. To our knowledge, the mechanism of type II flutter has not been disclosed in humans.     

Relation Between Left Atrial Size and Secondary Atrial Arrhythmias After Successful Catheter Ablation of Common Atrial Flutter

Catheter ablation ptovides an effective cure for patients with typical atrial flutter. However, these patients may have the potential to develop atrial tachyarrhythmias other than common atrial flutter. This study examines clinical and echocardiographic predictors for the occurrence of uncommon atrial flutter or atrial fibrillation after abolition of common atrial flutter. The study population comprised 17 patients (12 men, 5 women, age 32–74 years) who underwent successful radiofrequency catheter ablation of common atrial flutter. Common atrial flutter did not recur in any patient during a median follow-up time of 8 (range 1–25) months. Within a median of 7 (range 1–223) days, however, symptomatic atrial tachyarrhythmias occurred in 8 of 17 patients (47%): uncommon atrial flutter (n = 4); atrial fibrillation (n = 3); and both uncommon atrial flutter and atrial fibrillation in one patient. Preablation left atrial volume was significantly larger in patients who developed secondary arrhythmias compared with patients who remained in sinus rhythm (57.9 ± 15.6 vs 43.7 ± 16.4 cm³, P < 0.05). Enlarged left atrial volume dichotomized at 51 cm³ independently predicted postablation atrial arrhythmias (x²=5.11, rel. risk = 5.3, P < 0.05). On Kaplan-Meier analysis, time to occurrence of postablation atrial arrhythmias was significantly shorter in patietits with enlarged left atrium (P < 0.02). In conclusion, symptomatic uncommon atrial flutter and atrial fibrillation develops in a substantial proportion of patients after successful ablation of common atrial flutter. Out of a series of clinical and echocardiographic parameters, preablation left atrial size is the best predictor for the occurrence of these postablation atrial arrhythmias.     

Atrial Flutter: Lessons from Surgical Interventions (Musing on Atrial Flutter Mechanism)

We report our experience with seven patients who underwent direct surgical ablation of problematic common flutter. Intraoperative mapping was obtained in four patients. Surgical techniques varied over time. A circular incision of the right atrium was performed in the first patient. Two patients had epicardial cryoablation of the isthmus between the inferior vena cava and the tricuspid valve annulus. Four patients had extensive endocardial cryoablation of the isthmus. There were no immediate postoperative complications. One patient had atrial fibrillation 2 months postoperatively and underwent a corridor operation 1 year later. The other six patients are free of arrhythmias without antiarrhythmic drugs. Surgical ablation confirmed that the common form of atrial flutter is associated with a right atrial macroreentrant circuit. One of our intraoperative endocardial maps suggested that variant reentrant circuits can be associated with variant forms of flutter.     

Use of a New Non-Fluoroscopic Three-Dimensional Mapping System in Type I Atrial Flutter Ablation

We studied 40 patients who underwent cavo-tricuspid isthmus ablation for typical counterclockwise atrial flutter with cooled tip catheters between 2001 and 2003. Complete bi-directional isthmus block was created in all patients. A new, three-dimensional (3D), non-fluoroscopic mapping system was used in 20 patients (test group), and conventional fluoroscopy in 20 others (conventional group), using anatomic and electrophysiologic criteria in both groups. We measured the total procedure, ablation procedure, and overall fluoroscopy times, and the total number of radiofrequency (RF) applications delivered in the two groups. The overall fluoroscopy time was shorter in the test group (mean 8.8 minutes, range 2–17 minutes) than the conventional group (29.7 minutes, range 12–57 minutes; P < 0.001). Though the overall procedure time was similar in both groups (92.5 ± 28.6 minutes vs 106.5 ± 20.9 minutes; P = 0.067) the ablation duration (25.1 ± 6.6 minutes versus 43.3 ± 19.6 minutes; P = 0.0051) and the total RF applications (10.6 ± 9.4 versus 16.4 ± 9.4; P = 0.044) were smaller in the test group. The use of a new, 3D non-fluoroscopic mapping system markedly reduced the fluoroscopy exposure during typical atrial flutter ablation. It was also associated with a significant reduction in ablation time and in the number of RF applications. Since atrial flutter ablation is one of the most frequently performed procedures, this system may significantly reduce the overall amount of radiation exposure in high-volume laboratories.     

Atrial and Ventricular Pressures in Atrial Flutter

The hemodynamic effects of atrial flutter (AF) are unknown. The purpose of the present study was to investigate the changes in atrial and ventricular pressures after induction of AF. In 23 patients with paroxysmal AF (age 59 ± 9 years), a hemodynamic study was performed both during sinus rhythm and after induction of the tachyarrhythmia. During AF, 13 patients showed a fixed 2:1 AV conduction and 10 patients showed variable conduction. Mean right and left atrial pressures increased (P < 0.001) and right and left ventricular end-diastolic pressures decreased (P < 0.001) after induction of AF. Roth the increase in mean atrial pressures and the decrease in ventricular end-diastolic pressures were present either in the patients with fixed 2:1 AV (heart rate: 133 ± 15 beats/min) or in those with variable conduction (heart rate 96 ± 15 beats/min), but were more marked in the former. AF produces an impairment of atrial function, as evidenced by the increase in mean atrial pressures and reduction in ventricular end-diastolic pressures in the absence of an elevated heart rate. The mechanisms responsible for the increase in mean atrial pressures are unknown; however, atrial contractions against closed AV valves seem to play an important role.     

Overdrive and Programmed Atrial Electrostimulation in the Study of the Electrogenetic Mechanism of Atrial Flutter in Man

The response of atrial flutter (AF) to programmed atrial stimulation (PAS) (13 cases) and overdrive atrial pacing (OAP) ws studied in a total of 18 patients. During PAS the return cycle was equal to the basic cycle of AF in six patients, shorter in one patient, and slightly longer in six; it was never compensatory. ATrial flutter terminated in two patients by PAS and by OAP in three. In 4 patients, PAS resulted in an acceleration of the AF rate, followed by spontaneous interruption within 2 seconds. In the remaining patients, the stimulation either converted the AF into an uncommon type of AF (two patients) or into atrial fibrillation that was followed by spontaneous return to sinus rhythm. In two patients it was possible to reproduce the AF with PAS; in one of the patients another type of AF was induced. Some of the data observed suggest a re-entry circuit as the electrogenetic mechanism responsible for AF in man.     

Shift of Atrial Reentrant Tachycardia with Transient Entrainment to an Uncommon and a Common Type of Atrial Flutter

Atrial reentrant tachycardia (ART) which demonstrated transient entrainment shifted to an uncommon type of atrial flutter (AF) with premature atrial stimulation, and then returned to ART spontaneously, Subsequently, this ART shifted to a common type of AF by rapid atrial pacing, which was further transformed into an uncommon type of AF and finally terminated by rapid atrial pacing. The mechanism of AF in clinical cases is still controversial, but in this case, AF, both uncommon and common types, is considered due to macro-reentry within the atria. To explain (he shift of ART to AF and mutual transformation between common and uncommon type of AF, we made a schematic figure of reentry loop within (he atria of ART and AF.     

Focal Right Atrial Dysplasia and Atrial Flutter in a Patient with Myotonic Dystrophy

Focal dysplasia of the right atrium was identified postmortem in a 22-year-old man with myotonic dystrophy and sudden death. Antemortem cardiac abnormalities included a single syncopal episode associated with atrial flutter with exercise-induced 1:1 atrioventricular conduction, sinus node dysfunction, and mild mitral valve prolapse. Pathologically there was only mild conduction system disease and the ventricular myocardium was normal. Right atrial dysplasia, previously unreported in myotonic dystrophy, appears to have been an arrhythmogenic lesion in this patient, serving as a morphological substrate for reentry.     

Atrial Flutter Mapping and Ablation II. Radiofrequency Ablation of Atrial Flutter Circuits

The definition of the anatomical substrate of reentry in at rial flutter has allowed the recognition of narrow, critical areas of the circuit, where radiofrequencv ablation can interrupt reentry. In common flutter the isthmus between the inferior vena cava and the tricuspid valve appears the best target, but ablation between the coronary sinus and tricuspid valve can also be effective in some cases. In atypical flutter using the same circuit as common flutter in a “clockwise” direction, ablation of the same isthmus is effective. Flutter interruption is the main objective, but it does not mean complete isthmus ablation. If flutter remains inducible, new applications are delivered in the isthmus, until it is made noninducible. Complications are rare. Despite attaining noninducibility, flutter may recur, and new procedures may he needed to prevent recurrence. Atrial fibrillation can occur in up to 30% of the cases during follow-up, but it is generally well controlled with antiarrhythmic drugs, that were ineffective to treat flutter before ablation. In reentry circuits based on surgical atrial scars, ablation of an isthmus between the scar and the inferior vena cava can also be effective. Left atrial circuits are not known well enough to guide successful ablation.     

Persistent Atrial Fibrillation Converts to Common Type Atrial Flutter during CFAE Ablation

Background: Catheter ablation of persistent and long‐standing persistent atrial fibrillation (AF) is still challenging. So far different ablation techniques have been reported, including pulmonary vein isolation, additional linear lesions, ablation of complex fractionated atrial electrograms (CFAE), and combinations of these techniques. During ablation of CFAE, the occurrence of left atrial (LA) tachycardia is well known. The occurrence of right atrial flutter on the other hand is less well described. Methods: Here, we report three patients who had been ablated because of symptomatic persistent atrial fibrillation. Summary: In all patients, AF changed into a cavotricuspid isthmus = dependent right atrial flutter during ablation of CFAE in the LA. (PACE 2010; 33:304–308)     

The Induction of Atrial Flutter and Fibrillation and the Termination of Atrial Flutter by Esophageal Pacing

In patients with Wolff-Parkinson-White syndrome (WPW), it is important to assess the ventricular response during atrial flutter or fibrillation since conduction across the accessory pathway during these atrial rhythms may cause hemodynamic impairment or life-threatening ventricular arrhythmias. We have recently reported the effective use of an esophageal electrode in pacing the atrium. In this study we praspectively assessed the ability to induce atrial flutter and fibrillation by esophageal pacing in 23 patients with WPW or other electrophysiological abnormalities. An esophageal bipolar electrode with 29 mm interelectrode distance was positioned in the esophagus to record the most rapid and largest esophageal electrogram (mean distance of 36.6 ± 2.9 cm (SD) from the nares). Pacing was performed at cycle lengths of 40–340 ms (mean 166 ± 72), pulse durations of 7.0–9.9 ms, and currents of 10–25 mA. Atrial flutter alone was induced in 6 patients, fibrillation alone in 11 patients, and both arrhythmias in 5 patients, In one patient neither flutter nor fibrillation was induced by esophugeal pacing, and fibrillation was induced only with difficulty using intracavitary pacing. Of the 11 patients with flutter, the arrhythmia was terminated in 8 by esophageal pacing at cycle lengths of 160–220 ms fmean 176 ± 18 ms). All patients tolerated the procedure well with only mild to moderate discomfort. Therefore, esophageal pacing appears to offer an effective, well tolerated method of initiating atrial fibrillation and flutter and terminating atrial flutter and offers a potentially useful noninvasive method of following patients serially.     

Importance of Tachycardia Cycle Length for Differentiating Typical Atrial Flutter from Scar‐Related in Adult Congenital Heart Disease

Background: Radiofrequency catheter ablation (RFCA) for intraatrial reentrant tachycardia (IART) in congenital heart disease (CHD) remains difficult. Methods: Thirty‐four consecutive adult patients (age, 37.6 ± 12.8 years; male, 21) with previously repaired CHD and IART underwent an electrophysiological study and RFCA. CHD included atrial septal defect (ASD, n = 14), tetralogy of Fallot (n = 11), ventricular septal defect (n = 4), pulmonary atresia (n = 2), atrioventricular septal defect (n = 1), transposition of the great arteries (n = 1), and double‐outlet right ventricle (n = 1). Results: Duration of CHD repair to IART onset was 19.1 ± 8.5 years. Thirty and four patients had single‐ and double‐loop reentrant tachycardia, respectively. Among the total of 38 IARTs, which were mapped, 22 (57.9%) and 13 (34.2%) IARTs were cavotricuspid isthmus (CTI)‐dependent atrial flutter (AFL) and scar‐related AFL, respectively. Typical AFL electrocardiography findings including definite sawtooth appearance in inferior leads and positive F wave in lead V1 were observed in only 12 of 21 patients (57.1%) with CTI‐dependent AFL. CTI‐dependent AFL had a significantly longer tachycardia cycle length (TCL) than scar‐related AFL (267.6 ± 34.4 ms and 235.9 ± 37.0 ms, respectively; P = 0.031). TCL > 250 ms had 79% sensitivity as the cutoff value for differentiating CTI‐dependent from scar‐related AFL. The acute success rates of RFCA in CTI‐dependent and scar‐related AFLs were 85.7% and 90.0%, respectively. The recurrence rates in CTI‐dependent and scar‐related AFLs were 11.1% and 11.1%, respectively, during a follow‐up of 21.2 ± 28.3 months. Conclusions: CTI‐dependent AFL was the most common IART in adult patients with repaired CHD and was easily manageable by RFCA. TCL might help to differentiate CTI‐dependent AFL from other IARTs. (PACE 2012;35:1338–1347)     

Combined Transesophageal Left Atrial Pacing and Antiarrhythmic Therapy in the Treatment of Atrial Flutter

In order to terminate atrial flutter (AF) overdrive transesophageal left atrial pacing (TELAP) was performed in 760 patients with paroxysmal AF. There were 315 women and 415 men (mean age 59 years). In 260 patients, TELAP was used in an outpatient setting. Approximately half of the patients (51 %) had coronary artery disease and/or arterial hypertension, and 23% of the patients had no structural heart disease. The duration of AF ranged between 1 hour and 1 month. TELAP was performed in 312 patients without any antiarrhythmic drug (AAD) administration (group I) and in 448 patients after administration of AAD (procainamide and/or amiodarone) in conventional doses (group II). TELAP resulted in immediate return of sinus rhythm in 85 patients (27%) of group I and in 222 patients (50%) of group II (P < 0.001). TELAP converted AF to atrial fibrillation (AFIB) in 185 of group I and in 214 (48%) of the group II patients (P < 0.01). In addition, within 1–2 days after TELAP AFIB converted to sinus rhythm spontaneously or after AAD in 87 patients of group I (28%) and in 84 (19%)of the group II patients (P < 0.01). In general, sinus rhythm was restored in 172 (55%) of the group I and in 306 (68%) of the group II patients (P < 0.005). AF was converted to AFIB in 98 (31 %) of the group I and in 130 (29%) of the patients in group II patients (NS). TELAP was ineffective in 42 (13.5%) of the group I and in 12 (3%) of the group II patients (P < 0.001). TELAP was an effective noninvasive method for the treatment of recent onset AF. Our experience showed that after TELAP, sinus rhythm was restored in most of the patients with paroxysmal AF within 1–2 days. In some patients TELAP converted AF to AFIB, making it easier to control the heart rate with AAD. Treatment with AAD before TELAP increased its effectiveness.     

Ablation of Atrial Flutter in a Patient with a Tricuspid Valve Replacement after Endocarditis

Myocardial scars from heart surgery are a source of tachycardia, eventually causing late morbidity and sudden death. In general, catheter ablation has been shown to be an effective therapy for various rhythm disorders, but it has been rarely described after atrioventricular valve replacement. We report on a 45-year-old man who developed atrial flutter after implantation of a tricuspid valve bioprosthesis. An electrophysiological investigation revealed typical type-I counterclockwise atrial flutter that was successfully terminated by catheter ablation. A sinus rhythm was restored and remained stable during the course of treatment; the valvular function was not diminished. It is demonstrated that safe mapping and ablation of typical atrial flutter is possible after a tricuspid valve replacement.     

Uncommon Atrial Flutter: Characteristics, Mechanisms, and Results of Ablative Therapy

Thirty-seven patients with atrial flutter were studied with catheter mapping and radiofrequency ablation. Uncommon atrial flutter occurred in 20 out of 37 (54%) patients. Atrial endocardial mapping showed two types of uncommon atrial flutter. In 15 patients (group I) it was characterized by a single clockwise circuit whereas in 5 patients (Group II) it was characterized by the presence of more than one circuit and/or localized atrial fibrillation. RFA ablation was acutely successful in 14 out of 15 patients (93%) in Group I and in 2 oat of 5 (40%) patients in Group II. On long-term follow-up a significantly larger number of patients in Group I versus Group II (86% vs 20%) remained free of atrial flutter recurrence. We conclude that uncommon atrial flutter is a heterogeneous entity involving one or more reentrant circuits. Uncommon atrial flutter with multiple circuits may not be suitable for RFA.     

Radiofrequency Ablation of Atrial Flutter and Atrial Tachycardias in Patients with Permanent Indwelling Catheters

The presence of chronic indwelling leads in the area targeted for RF ablation may pose a technical challenge and reduce the chance of success of the ablation. In addition, application of lesions in close proximity to pacemaker leads or other permanent catheters could affect their function. Fourteen patients referred for RF ablation of atrial flutter/fibrillation and atrial tachycardia, who had a permanent dual chamber pacemaker (10 patients), ICD (1 patient), or both (3 patients) were studied to assess the safety, efficacy, and effects of the ablative procedure on device function. Lead impedance, R and P wave amplitude, and pacing threshold of the defibrillator and pacemaker were measured before and after ablation. The procedure was successful in all patients. In one patient who underwent both atrial flutter and atrial fibrillation ablation, the atrial pacing threshold increased from 1.0 preablation to 2.0 V postablation. No P wave was detectable after ablation. In another patient, the P wave amplitude went from 4.0 to 2.0 mV postablation. In both patients the device converted to the power reset mode. No changes were observed in the remaining patients. Postablation defibrillator testing showed no malfunction. Follow-up reinterrogation of the devices revealed no alterations. In conclusion: (1) RF ablation of atrial flutter and/or tachycardia is feasible even in patients with multiple chronic atrial and ventricular indwelling catheters; and (2) RF applications in close proximity of defibrillator and pacing catheters does not appear to alter their function unless lesions are produced in the area surrounding the distal pacing electrode.     

Type II Atrial Flutter Interruption with Transesophageal Pacing: Use of Propafenone and Possible Change of the Substrate

Type II atrial flutter (AFII) is an arrhythmia which usually cannot be interrupted by atrial pacing: the underlying mechanism is considered to be a leading circle without an excitable gap. We investigated whether the administration of propafenone, an antiarrhythmic drug, which primarily decreases conduction velocity, has a beneficial effect on AFII interruption using transesophageal pacing. Twelve patients with an AFII were randomized into 2 groups in which pacing was performed without treatment (group A) or two hours after the administration of 600 mg of oral propafenone (group B). Sinus rhythm was attained in 0 of 6 patients in group A and in 4 of 6 patients in group B (P < 0.05). The baseline mean cycle length was the same in both groups (175 ± 7 (A) vs 168 ± 8 ms (B); it lengthened significantly after the administration of propafenone (219 ± 33 vs 168 ± 8 ms; P < 0.05). Propafenone did not significantly lengthen the cycle in the two patients in whom interruption of the arrhythmia was impossible. Our data show that propafenone has a facilitating effect on atrial pacing only when it significantly prolongs the cycle length of the arrhythmia, possible expression of a conversion of AFII into type I, with an anatomical substrate and an excitable gap allowing arrhythmia capture and interruption. In the two patients in whom sinus rhythm was not restored, the absence of a direct dependence of the cycle length on the change in conduction velocity induced by propafenone may be explained by the persistence of a functionally determined circuit, resistant to atrial pacing.     

Long-Term Results of Hybrid Therapy in Patients with Atrial Fibrillation Who Develop Atrial Flutter During Flecainide Infusion

The flecainide infusion test has been proposed to screen candidates for hybrid pharmacological and ablation therapy. We report the long-term follow-up of 154 consecutive patients with paroxysmal or persistent atrial fibrillation (AF) who developed atrial flutter (AFL) during flecainide infusion (IC AFL), treated with inferior vena cava-tricuspid annulus isthmus catheter ablation and oral flecainide (hybrid therapy). Over a mean of 54.1 ± 13.1 months 82 patients (53%) remained free of AF and AFL. Flecainide was discontinued because of adverse effects in 6 patients (4%). A history of persistent AF, and the documentation of ≥1 spontaneous AFL episode before the flecainide test were independent predictors of successful hybrid therapy. In patients with paroxysmal AF without documented spontaneous AFL, the long-term efficacy of hybrid therapy was 38.5% (P = 0.03). The flecainide infusion test reliably detects candidates for hybrid therapy. The efficacy of this therapy is maintained over the long-term with a high patient compliance.