A comparison of transoesophageal atrial pacing and direct current cardioversion for the termination of atrial flutter: a prospective, randomised clinical trial

Transesophageal echocardiography of intracardiac thrombus in congenital heart disease and atrial flutter: the importance of thorough examination of the Fontan

Transesophageal echocardiography (TEE) is used in atrial flutter or fibrillation (AFF) before electric cardioversion to detect intracardiac thrombi. Previous studies have described the use of TEE to diagnose intracardiac thrombi in the left atrium and left atrial appendage, which has an incidence of 8 % among patients without congenital heart disease (CHD). In their practice the authors have noted a significant incidence of intracardiac thrombi in other structures of patients with CHD and AFF. This study aimed to determine the incidence and location of intracardiac thrombi using TEE in patients with CHD requiring electric cardioversion of AFF and to compare the use of TEE and transthoracic echo (TTE) to detect intracardiac thrombus in this population. A retrospective chart review of TEE and TTE findings for all patients with CHD who had electric cardioversion of AFF at our institution from 2005 to 2013 was conducted. The diagnosis, presence, and location of intracardiac thrombus were determined. The TEE and TTE results were compared. The study identified 27 patients with CHD who met the study entry criteria at our institution between 2005 and 2013. Seven of these patients had a single ventricle with Fontan palliation. All the patients presented with AFF and had TEE before electric cardioversion. No patients were excluded from the study. The patients ranged in age from 2 to 72 years (median, 21 years) and weighed 17-100 kg (median, 65 kg). The duration of AFF before TEE and attempted cardioversion ranged from 1 day to 3 weeks (median, 3.5 days). Intracardiac thrombus was present in 18 % (5/27) of the patients and in 57 % (4/7) of the Fontan patients with AFF. No embolic events were reported acutely or during a 6-month follow-up period. Among patients with CHD who present with AFF, a particularly high incidence of intracardiac thrombi is present in the Fontan patients that may be difficult to detect by TTE. Thorough TEE examination of the Fontan and related structures is indicated before electric cardioversion of AFF. The incidence of intracardiac thrombus in CHD patients is more than double that reported in non-CHD patients.

Effect of chronic amiodarone therapy on excitable gap during typical human atrial flutter

INTRODUCTION

Class I antiarrhythmic drugs increase duration of the excitable gap (EG) during typical atrial flutter whereas intravenous class III drugs decrease the EG. The effect of chronic oral amiodarone therapy on the EG is unknown.

METHODS AND RESULTS

EG was prospectively determined by introducing a premature stimulus and analyzing the response pattern during typical atrial flutter in 30 patients without antiarrhythmic drugs and in 20 patients under chronic oral amiodarone therapy. EG was calculated by the difference between the longest coupling interval leading to resetting and the effective atrial refractory period (EARP). A fully EG was defined by the portion of EG where the response curve of the return cycles was flat. A partially EG was defined by the portion of EG where the return cycle increases while coupling interval decreases. A resetting response curve was constructed by plotting the duration of the return cycle against the value of the coupling interval. Cycle length (CL; 222 +/- 17 vs 267 +/- 20 msec, P < 0.0001), EARP (128 +/- 16 vs 152 +/- 18 msec, P < 0.0001), and EG (54 +/- 19 vs 70 +/- 21 msec, P = 0.01) were significantly longer in patients taking amiodarone than in controls. Compared to CL, the relative part of the EARP (57 +/- 7 vs 57 +/- 6%, P = 0.96) and EG (24 +/- 7 vs 26 +/- 8%, P = 0.41) were comparable in both groups. The fully EG was larger in patients under chronic amiodarone therapy than in controls (39 +/- 21 vs 26 +/- 20 msec, P = 0.03). Neither duration of the partially EG (28 +/- 15 vs 31 +/- 15 msec, P = 0.42) nor slope of the ascending portion of the resetting response curve (1.15 +/- 0.5 vs 1.13 +/- 0.4 msec/msec, P = 0.71) differed between the two groups.

CONCLUSION

EG in patients under chronic amiodarone therapy is significantly larger than in controls, mainly because of a longer fully EG. This observation may be explained by opposite effects on conduction velocity and refractoriness.

A comparison of 50-J versus 100-J shocks for direct-current cardioversion of atrial flutter

BACKGROUND

Direct-current cardioversion remains the gold standard for restoration of sinus rhythm in patients with atrial flutter. Although an initial energy of 50 J is recommended, the optimal energy settings have not been evaluated in a large series of contemporary patients.

METHODS

We compared the outcome of cardioversion with 50 J versus 100 J in 330 consecutive patients with atrial flutter. Initial energy was based on attending physician preference. One hundred sixty patients received 50 J and 170 patients received 100 J.

RESULTS

Patients in both groups did not differ significantly in age, sex, weight, body mass index, duration of the arrhythmia, postoperative status, presence and type of structural heart disease, or use of antiarrhythmic drugs. Patients in the 100-J group had more first shock conversion (85% vs 70%; P =. 001), fewer total shocks (1.2 +/- 0.5 vs 1.4 +/- 0.7; P =.001), and less induction of atrial fibrillation (2% vs 11%; P =.002). There were no significant differences in overall restoration of sinus rhythm, cumulative energy delivered, anesthetic dose, and procedure room time. On multivariate analysis, delivery of 100 J was the strongest predictor of first shock success (odds ratio 2.6, 95% confidence interval 2.13 to 3.16; P <.001).

CONCLUSION

An initial energy of 100 J is more efficient for restoration of sinus rhythm in patients with atrial flutter.

Intracardiac overdrive pacing as a treatment of atrial flutter in a horse

A five-year-old warmblood mare with atrial fibrillation was treated with quinidine sulphate. The atrial rhythm changed to atrial flutter and, because there were toxic effects, the treatment was discontinued. Seven months after the occurrence of the atrial flutter, treatment with a rapid atrial pacing technique restored a normal sinus rhythm. One year after the pacing therapy the horse was still in sinus rhythm and had been brought back into training.

Efficacy of intravenous propafenone in termination of atrial flutter by overdrive transesophageal pacing previously ineffective

Fifty patients with symptomatic type I atrial flutter in whom termination of the arrhythmia with transesophageal stimulation was unsuccessful were randomized to undergo a repeat procedure after intravenous propafenone (n = 25) or placebo (n = 25). Immediate sinus rhythm recovery rate was 36% in the propafenone group and 4% in the placebo group (p = 0.005), indicating that intravenous propafenone increases the rate of successful transesophageal stimulation and can be used when a first attempt at conversion is ineffective.

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.

Direct-current cardioversion for the conversion of atrial flutter

Hemodynamically stable atrial flutter should be treated with direct-current cardioversion using 200 J as an initial setting. This can be accomplished in an outpatient setting, saving the cost of hospitalization and avoiding the hazards of drug therapy.

Atrial flutter termination by overdrive transesophageal pacing and the facilitating effect of oral propafenone

Transesophageal overdrive atrial pacing is effective and safe for atrial flutter termination. The influence of antiarrhythmic drug therapy on this procedure is controversial. In this study, we investigated whether oral propafenone may facilitate this procedure. Thirty patients with type I atrial flutter were randomized into 2 groups in which transesophageal pacing was attempted: group A, without treatment; and group B, after oral administration of propafenone 600 mg. Transesophageal pacing was effective in interrupting atrial flutter in 53% of patients (8 of 15) in group A and in 87% of patients (13 of 15) in group B. A significant lengthening of the flutter cycle was observed with respect to the baseline in patients given propafenone (261 +/- 23 vs 217 +/- 25, p < 0.01). Sinus rhythm resumed at a shorter paced cycle in group A patients (166 +/- 13 vs 187 +/- 14 ms, p < 0.01). The transesophageal threshold for stable atrial capture was significantly lower in group A (20.5 +/- 0.2 vs 23.3 +/- 1.2, p < 0.01). In no patient was the threshold for atrial capture higher than the pain threshold. We did not observe abrupt enhancement of atrioventricular conduction. We conclude that propafenone is effective and safe when used with transesophageal pacing in the termination of atrial flutter. The slowing effect of the drug on intraatrial conduction and the possible stabilizing effect on the reentry circuit appear to be outweighed by the positive effect of propafenone on the excitable gap of the circuit, facilitating its capture and accounting for the beneficial effect of the drug on arrhythmia termination.

Conversion of atrial flutter in pediatric patients by transesophageal atrial pacing: a safe, effective, minimally invasive procedure

Atrial reentry tachycardia, often termed atrial flutter, is an arrhythmia that is uncommon in the general pediatric population but is seen frequently in patients with congenital heart disease. One goal in treating the arrhythmia is to terminate it, returning the atrium to its underlying rhythm. This report describes the use of transesophageal atrial pacing to attempt termination of atrial reentry in 102 pediatric patients (158 episodes). The patients ranged in age from 1 hour to 41.5 years. Conversion was successful for 112 (71%) of 158 episodes. Six of the 112 episodes required an infusion of procainamide after initial attempts at pacing led to atrial fibrillation. There were no significant differences between the ages of patients or the duration of the tachycardia in comparing successful versus unsuccessful conversions. In contrast, the atrial cycle lengths for the successfully converted tachycardias were significantly greater than for unsuccessful attempts. Transesophageal atrial pacing is a safe and effective means of terminating atrial flutter in the pediatric population. It is minimally invasive, it can often be performed in an outpatient setting, and the technique may occasionally be facilitated by infusion of intravenous procainamide.

Clinical utility and the predictors of outcome of overdrive transesophageal atrial pacing in the treatment of atrial flutter

Transesophageal atria pacing (TEAP) using a pill electrode was performed in 49 patients with atrial flutter. The responses observed were (1) immediate sinus rhythm in 17 (35%), (2) delayed sinus rhythm in 13 (27%), (3) atrial fibrillation in 11 (22%), and (4) no success in 8 (16%) patients. Sinus rhythm was thus restored in 30 patients (61%). In group A, 12 of 17 patients (p < 0.05) had coronary artery disease. The patients in group D had echocardiographic evidence of right atrial enlargement (2.56 +/- 0.29 cm, p = 0.007), left atrial enlargement (4.6 +/- 0.12 cm, p < 0.0001), right ventricular dilatation (3.41 +/- 0.45 cm, p < 0.05), left ventricular dilatation (6.39 +/- 0.66 cm, p < 0.05), and depressed left ventricular ejection fraction (32 +/- 7%, p < 0.05). Optimal pacing rate (375 +/- 54 beats/min) was 41% higher than the mean atrial flutter rate (266 +/- 37 beats/min) for cardioversion to immediate sinus rhythm. Pacing current strength and the pulse width had no influence on the final outcome. On the basis of the result of the initial attempt, patients undergoing TEAP repetitively had an almost predictably similar outcome on the subsequent attempts. Thus, normal sinus rhythm could be resumed in most patients with atrial flutter by TEAP. It does not require general anesthesia and can be performed even in patients who have undergone digitalization, when a direct-current countershock may be of some concern.