Atypical atrial flutters

Pacemaker lead-related macroreentrant atrial tachycardia

Macroreentrant atrial circuits are frequently associated with scarring. Previous reports have shown the possible development of scar tissue that is adjacent to pacemaker (PM) leads. However, reports of PM lead-related reentrant tachycardia are scarce. We report the case of a 63-year-old woman who presented with macroreentrant atrial tachycardia (MAT), related to the atrial trajectory of an old single-lead ventricular PM, that was successfully treated with radiofrequency ablation after an conventional electrophysiological study ruled out isthmus-dependent atrial flutter and provided sufficient data to confirm this diagnosis.This report presents a case of MAT originating around the trajectory of a PM lead, probably because of scar tissue that developed adjacent to the lead. Experimental studies have already shown that interstitial atrial fibrosis may develop adjacent to a ventricular single-lead. This finding suggests that MAT develops in patients with this specific condition. Recognizing this condition is important for managing these arrhythmias and performing safe ablation with the preservation of PM lead integrity.

Current treatment options for atrial flutter and results with cryocatheter ablation

Rhythm disturbances arising in the upper chambers of the heart are not uncommon. They are associated with a heavy burden of illness for the affected individual, as well as society in general. Atrial flutter, a re-entrant atrial tachycardia, is one such rhythm disturbance. The objective of this review article is twofold: first, to provide a brief insight into atrial flutter and the typical treatments for this arrhythmia in clinical practice; and second, to give an in-depth account of cryocatheter ablation as a relatively new treatment option for this potentially debilitating condition. The many recent clinical studies documenting the use of cryocatheter ablation for treatment of atrial flutter are presented, and their results briefly discussed. Overall, as cryocatheter ablation embeds itself among the arsenal of treatments for atrial flutter, the promising results from clinical studies appear destined to elevate cryocatheter ablation to a premier position among the treatment options for atrial flutter.

Interatrial mechanical dyssynchrony shown by tissue doppler imaging during atrial flutter

Although regular supraventricular tachycardia is traditionally classified on the basis of P-wave morphology, diagnostic accuracy is limited to information obtained from surface electrocardiography. Intracardiac electrophysiology is a conclusive although invasive diagnostic method. We report a case of regular supraventricular tachycardia with a heart rate of 162 bpm. M-mode echocardiography of the interatrial septum clarified both the atrial rate and the ventricular response ratio. Tissue Doppler M-mode imaging demonstrated the delay between the posterior wall motion of the left and right atrium. Although it deserves further study, transthoracic echocardiography may provide useful information in addition to electrocardiography.

Outpatient electrical cardioversion of atrial fibrillation: 8 years' experience. Analysis of shock-related arrhythmias

BACKGROUND

Outpatient electrical cardioversion (EC) of atrial fibrillation is currently the standard of care. Shock-related arrhythmias may be particularly deleterious in this setting. Preoperative identification of high-risk patients may be very useful.

METHODS

A retrospective analysis was made of 543 consecutive elective EC procedures in 457 outpatients over an 8-year period in a university cardiological institute. The protocol included adequate anticoagulation, intravenous anesthesia, direct current shock, and a direct observation after a shock to detect procedure-related complications. No patients were excluded due to severity of pathology or comorbidities. Clinical characteristics, energy delivered, medications, arrhythmic phenomena, and predictors of success and complications were analyzed.

RESULTS

Of 543 ECs performed, 88.2% restored sinus rhythm, which persisted at discharge in 83.2%. No anesthesia-related complications were detected. No thromboembolic complications were detected. Use of a biphasic cardioverter was the only predictor of success (P = 0.0001). The bradyarrhythmic complication rate was 1.5%. No ventricular arrhythmic events were detected. Atrial flutter was present in five of eight patients who developed complications versus 44 of 535 patients who had no complications (P < 0.0005), and prosthetic heart valves in four of eight complicated versus 40 of 535 uncomplicated cases (P = 0.0044). The combination of atrial flutter and prosthetic heart valve was found in four of eight complicated versus 11 of 535 uncomplicated cases (P < 0.0005).

CONCLUSION

Shock-related arrhythmias are essentially bradyarrhythmias. Atrial flutter and previous cardiac surgery identify a subgroup of patients at high risk of postshock bradyarrhythmic complications.

Prediction of the atrial flutter circuit location from the surface electrocardiogram

Identification of atypical atrial flutter (AFL) (non-cavo-tricuspid isthmus-dependent) prior to the electrophysiology laboratory is potentially useful because it allows appropriate procedural planning and enables discussion of the likely success rates and risks of the procedure with the patient. Typical counterclockwise AFL has a stereotypic appearance, the electrocardiogram (ECG) is predictive of the diagnosis in the majority of cases, and ablation procedures are associated with a high degree of safety and success. Atypical right atrial and left AFLs have a highly variable flutter wave morphology and may appear atypical, resemble typical flutter or appear to be focal in origin. Targeting these complex and often multiple re-entrant circuits is aided by expertise and use of electroanatomic mapping systems. This review will address whether there are clues from the 12-lead ECG which assist in the localization of AFL circuits.

Clinical prediction of cavotricuspid isthmus dependence in patients referred for catheter ablation of "typical" atrial flutter

INTRODUCTION

Typical atrial flutter (AFL) can be cured by catheter ablation of the cavotricuspid isthmus (CTI). The surface electrocardiogram (ECG) is not always diagnostic of isthmus dependence of AFL. The aim of this study was to evaluate clinical parameters for the prediction of isthmus-dependent AFL.

METHODS AND RESULTS

Sixty consecutive adult patients without suspected atriotomy-related AFL, congenital heart disease, or previous AFL ablation, referred for catheter ablation of presumed typical AFL were studied. All patients had distinct flutter waves in the inferior leads, suggestive of CTI-dependent AFL, either on presentation to the electrophysiology (EP) lab or documented on prior ECG. Electrophysiology study was performed in the standard fashion. Patients who presented to the EP laboratory not in AFL underwent arrhythmia induction with a burst pacing protocol. A clinical history of persistent AFL (P = 0.0001) and existence of AFL on presentation to the EP laboratory (P = 0.0001) were strong predictors of CTI dependence. History of atrial fibrillation (P = 0.19), structural heart disease (P = 0.6), hypertension (P = 0.4), and previous cardiac surgery (P = 0.5), as well as the nature of AFL-related symptoms (P = 0.5), were not predictors of CTI-dependent AFL documented during EP study.

CONCLUSION

In patients with ECG suggestive of typical AFL, the presence of persistent rather than paroxysmal AFL and presentation to the EP laboratory in AFL are strong predictors of CTI-dependent AFL. A paroxysmal pattern of AFL predicts noninducibility of CTI-dependent AFL during EP study. CTI ablation may therefore be less effective in these patients.

Atypical flutter: a review

Understanding of typical flutter circuits led the way to the study of other forms of macroreentrant tachycardias of the atria, and to their treatment by catheter ablation. It has become evident that the ECG classification of atrial flutter and atrial tachycardia by a rate cutoff and the presence or absence of isoelectric baselines between atrial deflections is not a valid indicator of tachycardia mechanism. Macroreentrant circuits where activation rotates around large obstacles are the most common arrhythmias found in patients with atypical forms of flutter or atrial tachycardia, especially after surgery for congenital heart disease, however, focal mechanisms can also be found. Large areas of low voltage electrograms, suggestive of severe myocardial damage (fibrosis or infiltration) can be found in many atypical macroreentrant tachycardias at the center of the circuit. Many of these circuits can be mapped precisely, critical isthmuses can be defined, and effective catheter ablation can be performed. The need to match activation maps with anatomy precisely, makes computer assisted, anatomically precise mapping a useful tool. Entrainment techniques have to be used sparingly to avoid tachycardia interruption. In complex cases, ablation can be done in sinus rhythm, after definition of conducting channels between low voltage areas and scars or anatomic obstacles. Long-term prognosis is uncertain and depends on the underlying pathology.