Absence of a resetting phenomenon suggests that a sling works as a part of the supraventricular tachycardia circuit involving twin atrioventricular nodes: A case of corrected transposition of the great arteries

Atypical sites of twin atrioventricular nodes in a rare form of univentricular heart

Twin atrioventricular nodes (AVNs) associated with complex tachycardias has been described in a heart with discordant atrioventricular (AV) connection. The present case had twin AVNs (approximately 3 o'clock and 8 o'clock position) of sole AV annulus with absent right AV connection. It is a first report demonstrated the twin AVNs identified at atypical sites associated with a univentricular heart with single inlet connection.

Multicenter Outcomes of Catheter Ablation for Atrioventricular Reciprocating Tachycardia Mediated by Twin Atrioventricular Nodes

OBJECTIVES

This study sought to describe the electrophysiologic properties and catheter ablation outcomes for T-AVRT.

BACKGROUND

Although catheter ablation for atrioventricular (AV) reciprocating tachycardia via twin AV nodes (T-AVRT) is an established entity, there are few data on the electrophysiological properties and outcomes of this procedure.

METHODS

An international, multicenter study was conducted to collect retrospective procedural and outcomes data for catheter ablation of T-AVRT.

RESULTS

Fifty-nine patients with T-AVRT were identified (median age at procedure, 8 years [interquartile range, 4.4-17.0 years]; 49% male). Of these, 55 (93%) were diagnosed with heterotaxy syndrome (right atrial isomerism in 39, left atrial isomerism in 8, and indeterminate in 8). Twenty-three (39%) had undergone Fontan operation (12 extracardiac, 11 lateral tunnel). After the Fontan operation, atrial access was conduit or baffle puncture in 15 (65%), fenestration in 5 (22%), and retrograde in 3 (13%). Acute success was achieved in 43 (91%) of 47 attempts (targeting an anterior node in 23 and posterior node in 24). There was no high-grade AV block or change in QRS duration. Over a median of 3.8 years, there were 3 recurrences. Of 7 patients with failed index procedure or recurrent T-AVRT, 6 (86%) were associated with anatomical hurdles such as prior Fontan or catheter course through an interrupted inferior vena cava-to-azygous vein continuation (P = 0.11).

CONCLUSIONS

T-AVRT can be targeted successfully with low risk for recurrence. Complications were rare in this population. Anatomical challenges were common among patients with reduced short and long-term efficacy, representing opportunities for improvement in procedural timing and planning.

Retrograde sharp potential resembling the his-bundle electrogram: is this a case of atrioventricular re-entrant tachycardia involving twin atrioventricular nodes with the anterior node exhibiting only retrograde conduction?

A 2-year-old male with right isomerism was referred for supraventricular tachycardias. Atrial pacing study revealed that anterograde conduction was only through the posterior atrioventricular node. During the mapping of ventriculoatrial conduction, we identified a sharp potential resembling a His-bundle electrogram with a decremental property at the anterior wall of the common atrium. Catheter ablation for the potential eliminated the anterior ventriculoatrial conduction, thereby indicating retrograde activation of the possible anterior atrioventricular node.

Impact of preoperative electrophysiological intervention on occurrence of peri/postoperative supraventricular tachycardia following Fontan surgery

BACKGROUND

Little is known about the effects of preoperative electrophysiological study (EPS) and catheter ablation (CA) in Fontan surgery candidates with supraventricular tachycardia (SVT).

OBJECTIVE

The purpose of this study was to investigate the clinical impact of EPS-guided intervention in Fontan surgery candidates with preceding SVT events.

METHODS

A total of 109 consecutive patients with a history of SVT before Fontan surgery were divided into 3 groups: 44 in whom EPS with CA was attempted (CA group); 21 in whom EPS without CA was attempted (EPS group); and 44 in whom EPS was not performed (N group). The incidence and diagnosis of SVT, acute success rate of CA, and risk factors of peri/postoperative SVT were retrospectively investigated.

RESULTS

The total incidence of SVT within 1 year after Fontan surgery was 34% (n = 37), with 91% of cases occurring within 1 month. Among the 71 SVT incidences diagnosed with EPS, 31 were atrioventricular reentrant tachycardias (AVRTs) involving twin atrioventricular nodes, 12 were atrioventricular nodal reentrant tachycardias, 12 were atrial tachycardias, 7 were orthodromic AVRTs via the accessory pathway, 7 were atrial flutters, and 2 were junctional tachycardias. The acute success rate of CA was 91% (48/53). The rate of peri/postoperative atrioventricular reciprocating SVT was significantly lower in the CA group than in the N or EPS group (11% vs 43% or 43%; P <.05). No/unsuccessful CA significantly increased the risk of peri/postoperative SVT in multivariate analysis (odds ratio 4.43; 95% confidence interval 1.69-11.59).

CONCLUSION

Preoperative CA reduces peri/postoperative SVT occurrence in Fontan surgery candidates at high risk for SVT.

Electrophysiology Study for Complex Supraventricular Tachycardia in Congenital Heart Disease Patients With Single-Ventricle Physiology

BACKGROUND

Supraventricular tachycardia (SVT) is common in complex congenital heart disease (CCHD) patients with single-ventricle physiology and may cause hemodynamic deterioration. We reported the outcomes of catheter ablation for such complex SVT in these single-ventricle CCHD patients.

METHODS AND RESULTS

Patients with single-ventricle physiology (defined as CCHD patients) who received electrophysiology studies and catheter ablation between 1995 and 2015 were studied. We enrolled 30 CCHD patients (18 with right atrial isomerism, 5 with left atrial isomerism, and 7 with other CCHDs; 17 male, 13 female). The age of onset of clinical SVT was 6.7 years (±4.7 years). Electrophysiology studies and ablation were performed at age 7.1 years (±3.9 years); body weight was 20.7 kg (±10.0 kg). Twin atrioventricular nodes were present in 60% of patients (right atrial isomerism, 72.2%; left atrial isomerism, 40%; other CCHDs, 42.9%). Manifested preexcitation was noted in 10% of patients. SVT was induced in 21 patients. Twin atrioventricular nodal reentrant tachycardia was the most common (57.1%), followed by atrioventricular reentrant tachycardia (28.6%), junctional tachycardia (14.3%), and atrioventricular nodal reentrant tachycardia (9.5%). Multiple arrhythmias were common (33.3%), particularly in patients with atrioventricular reentrant tachycardia (50%). Ablation successfully eliminated SVT in 12 of 14 patients (85.7%), with a recurrence rate of 16.7% during 6 years of follow-up.

CONCLUSIONS

Transcatheter ablation of complex SVT substrates, including minor atrioventricular node of twin atrioventricular nodal reentrant tachycardia, accessory pathways of atrioventricular reentrant tachycardia, and a slow pathway of atrioventricular nodal reentrant tachycardia, is effective in CCHD patients. The limitations are limited vascular access and the risk of atrioventricular block.