Atrioventricular nodal reentrant tachycardia with multiple discontinuities in the atrioventricular node conduction curve: immediate success rates of radiofrequency ablation and long-term clinical follow-up results as compared to patients with single or no AH-jumps

Catheter ablation via the left atrium for atrioventricular nodal reentrant tachycardia: A narrative review

Background

Since 1996, it has been recognized that catheter ablation for atrioventricular nodal reentrant tachycardia (AVNRT) may require an approach through the left atrium.

Objective

The purposes are to present a case report and to provide a comprehensive narrative review on this topic.

Methods

A literature review of all articles that provided detailed information on patients who underwent catheter ablation via the left atrium for AVNRT was performed. The primary search queried PubMed using Medical Subject Headings (MeSH) terms "atrioventricular nodal reentrant tachycardia" and "left." The secondary search was performed by manual review of reference lists and Google Scholar citations of manuscripts retrieved by the primary search. The review was limited to the English language.

Results

The searches yielded 30 articles that described 79 patients. A case report was added. Therefore, the final review consisted of 80 patients. The prevalence of left atrial ablation for patients with AVNRT undergoing catheter ablation at tertiary care centers was approximately 1%. Failed right atrial ablation, with or without coronary sinus ablation, was the most common indication for left atrial ablation. Pooled data from 3 cohort studies estimated the acute success rate for radiofrequency ablation of the slow pathway at the septal or inferoparaseptal segments of the mitral valve annulus after failed right-sided ablation to be 90%. There were no reports of atrioventricular block requiring permanent pacemaker implantation.

Conclusion

Catheter ablation of the slow pathway via the left atrium is an important technique for AVNRT cases that are refractory to conventional ablation.

Radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia in children and adolescents: a single center experience

Purpose

Atrioventricular nodal reentry tachycardia (AVNRT) is less common in pediatric patients than in adult patients. Thus, data for pediatric AVNRT patients are insufficient. Hence, we aimed to analyze the patient characteristics, treatment, and any recurrences in pediatric AVNRT patients.

Methods

We reviewed the records of 50 pediatric AVNRT patients who had undergone radiofrequency catheter ablation (RFCA) between January 1998 and December 2016 at a single regional center. The patients were aged ≤18 years.

Results

Among 190 pediatric patients who underwent RFCA for tachyarrhythmia, 50 (26.3%; mean age, 13.4±2.6 years) were diagnosed as having AVNRT by electrophysiological study. Twenty-five patients (25 of 50, 50%) were male. Twenty patients (20 of 50, 40%) used beta-blockers before RFCA. All patients had no structural heart disease except 1 patient with valvular aortic stenosis and coarctation of the aorta. RFCA was performed using the anatomic approach under fluoroscopic guidance. The most common successfully ablated region was the midseptal region (25 of 50, 50%). Slow pathway (SP) ablation and SP modulation were performed in 43 and 6 patients, respectively. Complication occurred in 1 patient with complete atrioventricular block. During follow-up, 6 patients had recurrence of supraventricular tachycardia, as confirmed by electrocardiography. Among them, 5 underwent successful ablation at the first procedure. In 1 patient, induction failed during the first procedure.

Conclusion

RFCA is safe and effective in pediatric AVNRT patients. However, further research is needed for establishing the endpoints of ablation in pediatric AVNRT patients and for identifying risk factors by evaluating data on AVNRT recurrence after RFCA.

Cardiac electrophysiology in mice: a matter of size

Over the last decade, mouse models have become a popular instrument for studying cardiac arrhythmias. This review assesses in which respects a mouse heart is a miniature human heart, a suitable model for studying mechanisms of cardiac arrhythmias in humans and in which respects human and murine hearts differ. Section I considers the issue of scaling of mammalian cardiac (electro) physiology to body mass. Then, we summarize differences between mice and humans in cardiac activation (section II) and the currents underlying the action potential in the murine working myocardium (section III). Changes in cardiac electrophysiology in mouse models of heart disease are briefly outlined in section IV, while section V discusses technical considerations pertaining to recording cardiac electrical activity in mice. Finally, section VI offers general considerations on the influence of cardiac size on the mechanisms of tachy-arrhythmias.

P wave dispersion predicts recurrence of paroxysmal atrial fibrillation in patients with atrioventricular nodal reentrant tachycardia treated with radiofrequency catheter ablation

BACKGROUND

Paroxysmal atrial fibrillation (AF) recurs in up to one-third of patients with atrioventricular nodal reentrant tachycardia (AVNRT) treated with slow pathway ablation. Therefore, identification of patients at risk for recurrence of AF after slow pathway ablation is important because of the necessity for additional therapies. The purpose of this study was to determine whether successful slow pathway ablation influences P wave parameters and whether these parameters predict the recurrence of paroxysmal AF in patients with both AVNRT and paroxysmal AF after ablation.

METHODS

Thirty-six patients with AVNRT and documented paroxysmal AF (Group 1) were compared to 36 age-matched controls with AVNRT only (Group 2). P wave durations and P dispersion were measured before and after ablation.

RESULTS

No significant differences were observed between P wave parameters observed before and after ablation. Maximum P wave durations (Pmax) and P dispersion (Pdisp) were significantly higher in Group 1 than in Group 2 (P < 0.001 for both) whereas minimum P wave durations did not differ between groups, both before and after ablation. Ten patients (28%) in Group-1 had recurrence of AF during a mean follow-up of 34 +/- 11 months. Univariate predictors of AF recurrence were Pdisp > or =35.5 ms (P < 0.010), left atrial diameter >40 mm (P < 0.010), mitral or aortic calcification (P < 0.010), Pmax > or =112 ms (P < 0.050), valvular heart disease (P < 0.050), and atrial vulnerability (induction of AF lasting >30 second) after ablation (P < 0.050). However, only Pdisp > or =35.5 ms (P < 0.050) and left atrial diameter >40 mm (P < 0.010) were independent predictors of AF recurrences.

CONCLUSION

This study suggests that P wave dispersion could identify patients with AVNRT susceptible to recurrence of AF after slow pathway ablation.

Characteristics of Slow Pathway Conduction After Successful AVNRT Ablation

BACKGROUND

AV node slow pathway conduction can persist following successful ablation for AV node reentrant tachycardia (AVNRT). We hypothesized that careful examination of AV nodal conduction curves before and after effective AVNRT ablation in patients with persistent slow pathway conduction could shed light on this apparent paradox.

METHODS AND RESULTS

Thirty patients (age 40.9 +/- 14.3; 8 male) were included. AV node function curves were created based on pre- and postablation atrial extrastimulus testing. Analysis of slow pathway function curves demonstrated significant decrease in AH for any given coupling interval after ablation (mean difference -68.1 [-94.5, -41.7] P < 0.001), graphically indicated by downward displacement of the curve. In addition, mean slow pathway effective refractory period (ERP) increased from 247.9 +/- 36.1 msec to 288.6 +/- 56.0 msec (P < 0.001); mean maximum AH interval decreased from 361.3 +/- 114.2 msec to 306.9 +/- 65.2 msec (P = 0.013); mean difference in minimum and maximum AH interval during slow pathway conduction decreased (from 94.5 +/- 75.8 msec to 59.6 +/- 46.2 msec (P = 0.016). Finally, mean difference between the fast and slow pathway effective refractory periods, the span of coupling intervals over which slow pathway conduction occurred, decreased (from 113.9 +/- 61.4 msec to 63.2 +/- 41.5 msec, P = 0.001).

CONCLUSIONS

Ablation, which successfully eliminates inducible and spontaneous AVNRT in the presence of persistent slow pathway conduction, is associated with significantly altered slow pathway conduction characteristics, indicating the presence of a damaged or different slow pathway after ablation, incapable of sustaining tachycardia.

Atrioventricular Nodal Reentrant Tachycardia with Paroxysmal Atrial Fibrillation: Clinical and Electrophysiological Features and Predictors of Atrial Fibrillation Recurrence Following Elimination of Atrioventricular Nodal Reentrant Tachycardia

INTRODUCTION

Clinical and electrophysiological characteristics of patients with atrioventricular nodal reentrant tachycardia (AVNRT) and paroxysmal atrial fibrillation (AF) have not been studied in a large patient cohort. We aimed to define the clinical features and cardiac electrophysiological characteristics of these patients, and to examine the incidence and identify predictors of AF recurrences after elimination of AVNRT.

METHODS AND RESULTS

Thirty-six patients with AVNRT and documented paroxysmal AF (Group 1) and 497 patients with AVNRT alone undergoing ablation in the same period (Group 2) were studied. There were no significant differences between groups regarding clinical features, except age, which was higher in Group 1 (p<0.001). Presence of atrial vulnerability (induction of AF lasting>30 seconds) and multiple AH jumps (>or=50 ms) before ablation were significantly more prevalent in Group 1 (p<0.001, p=0.010 respectively). During follow-up of 34 +/- 11 months, AF recurred in 10 patients (28%) in Group 1, while 2 patients in Group 2 (0.4%) developed paroxysmal AF (p<0.001). Univariate predictors of AF were: left atrial diameter>40 mm (p=0.001), presence of mitral or aortic calcification (p=0.003), atrial vulnerability after ablation (p=0.015) and valvular disease (p=0.042). However, independent predictors of AF recurrences were left atrial diameter>40 mm (p=0.002) and the presence of atrial vulnerability after ablation (p=0.034).

CONCLUSION

In patients with both AVNRT and paroxysmal AF, the recurrence rate of AF after elimination of AVNRT is 28%. Left atrial diameter greater than 40 mm and atrial vulnerability after elimination of AVNRT are independent predictors of AF recurrences in the long term.

Atrioventricular Nodal Reentrant Tachycardia Ablated From Left Atrial Septum Clinical and electrophysiological characteristics and long-term follow-up results as compared to conventional right-sided ablation

Radiofrequency catheter ablation or modification of the slow pathway is almost always performed on the right atrial side of the interatrial septum, however, this is not possible in rare cases. We evaluated the clinical and electrophysiological characteristics and long-term follow-up results of patients whose AVNRT could only be ablated from the left posterior atrial septum after repeated unsuccessful attempts on the right atrial side and to observe if they differ from those undergoing ablation with the conventional right-sided approach. Of 587 cases with symptomatic typical AVNRT, 9 patients (1.5%) in whom RF energy delivered to the right atrial septum with the integrated approach failed to ablate or modify the slow pathway were enrolled in the study group (group 1) while the others served as controls (group 2). There was no significant difference between the groups regarding clinical characteristics, dual AV nodal physiology, sinus cycle lengths, AH and HV intervals, procedural complication rates, or recurrence rates in the mean follow-up duration of 34 +/- 11 months. Only tachycardia cycle length (TCL) was significantly higher in group 1 than in group 2, which was mainly due to the difference in AH intervals (P < 0.001 for both). Slow pathway ablation was performed at the posteroseptal aspect of the mitral annulus in 6 and the midseptal aspect in 2 cases. In 1 case, attempts at ablation on the left atrial septum also failed. When the conventional right-sided approach fails to ablate or modify the slow pathway conduction, left-sided ablation can safely and effectively be employed, with success rates and long-term follow-up results comparable to the conventional right-sided approach.