Atypical Atrioventricular Nodal Reentry Research Articles

Low-voltage bridge strategy to guide cryoablation of typical and atypical atrioventricular nodal re-entry tachycardia in children: mid-term outcomes in a large cohort of patients.

In the current literature, results of the low-voltage bridge (LVB) ablation strategy for the definitive treatment of atrioventricular nodal re-entry tachycardia (AVNRT) seem to be encouraging also in children. The aims of this study were (i) to prospectively evaluate the mid-term efficacy of LVB ablation in a very large cohort of children with AVNRT, and (ii) to identify electrophysiological factors associated with recurrence. One hundred and eighty-four children (42% male, mean age 13 ± 4 years) with AVNRT underwent transcatheter cryoablation guided by voltage mapping of the Koch's triangle. Acute procedural success was 99.2% in children showing AVNRT inducibility at the electrophysiological study. The overall recurrence rate was 2.7%. The presence of two LVBs, a longer fluoroscopy time and the presence of both typical and atypical AVNRT, were found to be significantly associated with an increased recurrence rate during mid-term follow-up. Conversely, there was no significant association between recurrences and patient's age, type of LVB, lesion length, number of cryolesions or catheter tip size. The LVB ablation strategy is very effective in AVNRT treatment in children. Recurrences are related to the complexity of the arrhythmogenic substrate.

Delta of the local ventriculo-atrial intervals at the septal location to differentiate tachycardia using septal accessory pathways from atypical atrioventricular nodal re-entry.

Tachycardia mediated by septal accessory pathways (AP) and atypical atrioventricular nodal re-entry (AVNRT) require careful electrophysiologic evaluation for differential diagnosis. We aim to describe the differential behaviour of local ventriculo-atrial (VA) intervals which predicts the tachycardia mechanism. The local VA intervals at the para-Hisian septum were measured under three different situations: (i) tachycardia; (ii) sustained entrainment from the right ventricular apex (RVA); and (iii) continuous pacing from the RVA during sinus rhythm. Differences were computed as follows: Δ-VAentr = VA during entrainment - VA during tachycardia; and Δ-VApac = VA while pacing during sinus rhythm - VA during tachycardia. In contrast to AVNRT, we hypothesized that an invariable retrograde conduction through the septal AP will keep the result of the subtractions close to 0 ms in cases of ortodromic atrioventricular re-entrant tachycardia (AVRT). We analysed 55 atypical AVNRT (45% posterior type) and 82 AVRT (10 anteroseptal, 18 para-Hisian, 12 mid-septal, and 42 posteroseptal). Δ-VAentr was longer for AVNRT (98.5 ± 40.3 ms) compared with septal AP (-5.7 ± 19.3 ms; P < 0.001). A value of 50 ms showed 98.7% sensitivity and 92% specificity (AUC 0.99; 95% CI 0.98-1). According to physiological criteria, a negative Δ-VAentr remains unobserved in the case of AVNRT (positive predictive value 100% for septal AP). Δ-VApac was also longer for AVNRT (66.5 ± 14.6 ms) compared with septal AP (-9.7 ± 3.3 ms; P < 0.001). A value of 50 ms showed 100% sensitivity and 74% specificity (AUC 0.86; 95% CI 0.76-0.93). Delta of the local VA intervals enables distinction between atypical AVNRT and AVRT mediated by septal AP.

Transseptal puncture for radiofrequency catheter ablations of left-sided arrhythmias in a paediatric population.

Puncturing the atrial septum is frequently used in adults. In children, the transseptal puncture is less common, technically more demanding, and the rate of complications is not well described. We studied the feasibility and safety of this procedure in a retrospective analysis of 157 consecutive children undergoing transseptal puncture for radiofrequency catheter ablation of left atrial targets in two tertiary-care centres between 2005 and 2013. The median age of the patients at intervention was 12.5 years (1.1-18 years), with median weight of 42 kg (range 9.0-97.0 kg). Pre-excitation was found in 102 procedures, accessory pathway with exclusively retrograde conduction in 41, focal atrial tachycardia in nine, left-sided permanent junctional/reciprocating tachycardia-like accessory pathways in three, and atypical atrioventricular nodal re-entry tachycardia in two. All the procedures were guided by fluoroscopy. Additional imaging by transoesophageal echocardiography was used in three patients. Successful transseptal puncture was possible in 99.4% of the cases, ablation in 97.4%. The median time, including mapping and radiofrequency ablation, was 120 minutes (range 60-450), the median fluoroscopy time 10.8 minutes (range 1.8-75), and the median radiation dose 3 Gy cm2 (range 0.3-35). In total, five patients (3.2%) had a recurrent arrhythmia during the observation period of a median of 40 months (range 1-103). No complications associated with the transseptal puncture were observed. Transseptal puncture is a feasible and safe procedure in children. This access allows successful and efficient radiofrequency ablation of arrhythmia of the left atrium in the vast majority of the patients and might be considered as the first-line approach in this population.

Differential Responses of the Septal Ventricle and the Atrial Signals During Ongoing Entrainment: A Method to Differentiate Orthodromic Reciprocating Tachycardia Using Septal Accessory Pathways From Atypical Atrioventricular Nodal Reentry.

Differential diagnosis between tachycardia mediated by septal accessory pathways (AP) and atypical atrioventricular nodal reentry can be challenging. We hypothesized that an immediate versus delayed pace-related advancement of the atrial electrogram, once the local septal parahisian ventricular electrogram (SVE) has been advanced, may help in this diagnosis. We focused on differential timing between SVE and atrial signals at the initiation of continuous right ventricular apical pacing during tachycardia. SVE advancement preceding atrial reset was defined as SVE advanced by the paced wave fronts while atrial signal continued at the tachycardia cycle. We analyzed 51 atypical atrioventricular nodal reentry (45% posterior type) and 80 AP tachycardias (anteroseptal [10], parahisian [18], midseptal [12], and posteroseptal [40]). SVE advancement preceding atrial reset was observed in 98% of atrioventricular nodal reentries during 4±1.1 cycles; this phenomena was observed in 6 (8%) of the atrioventricular reentrant tachycardia mediated by septal AP (P<0.001; sensitivity 98%; specificity 93%; positive predictive value 90%; negative predictive value 99%) and lasted 1 single cycle (P<0.001). Right posteroseptal AP tachycardias were distinctly characterized by atrial reset preceding SVE advancement (with ventricular fusion; specificity 100%; positive predictive value 100%). In 11 cases, it was impossible to achieve sustain entrainment. In all of them, the differential responses at the entrainment attempt allowed for appropriate diagnosis. The differential response of the SVE and the atrial electrogram at the initiation of continuous right ventricular apical pacing during tachycardia effectively distinguishes between atypical atrioventricular nodal reentry and atrioventricular reentrant tachycardia mediated by septal APs.

Simplified Automated Right Ventricular Overdrive Pacing for Rapid Diagnosis of Supraventricular Tachycardia

Objectives: The purpose of this study was to prospectively evaluate the feasibility and diagnostic value of right ventricular overdrive pacing (RVOP) during supraventricular tachycardia (SVT) using a 2-catheter approach with automatic pacing from the right ventricular inflow (RVIT) and outflow tract (RVOT). Methods: One hundred and thirty-six consecutive patients (with 138 arrhythmias, mean age 36 ± 20 years, range 4-95) were enrolled in this study. Only coronary sinus and ablation catheters were used. RVOP was delivered from RVIT and then from RVOT. Each attempt consisted of 10 synchronized beats delivered at a cycle length of 10-40 ms longer than the tachycardia cycle length. Results: RVOP was sufficient to confirm the transition zone within the first 9 beats in the majority of SVTs. Atrial perturbation (acceleration, delayed) in the transition zone was detected in all patients with orthodromic atrioventricular (AV) reentry. Patients with typical AV nodal reentry, atypical AV nodal reentry and atrial tachycardia did not show atrial timing perturbation during fusion complexes of RVOP. Conclusions: Synchronized RVOP from RVIT or RVOT is an easy and accurate method for the quick and reliable differential diagnosis of SVT in various clinical settings, particularly when only a limited number of catheters are used.

P-174 Detailed Electroanatomical Mapping of Slow and Intermediate Pathway in Atypical Atrioventricular Nodal Reentry Tachycardia

P-174 Detailed Electroanatomical Mapping of Slow and Intermediate Pathway in Atypical Atrioventricular Nodal Reentry Tachycardia

724-4 Coexistence of Typical and Atypical Atrio-ventricular Nodal Reentry: Evidence for Multiple Pathways of Slow Conduction

The nature of the atrio-ventricular nodal (AVN) reentry circuit is still a source of debate. We studied two patients in which both typical (slow-fast, SF) AVN reentrant tachycardia and atypical (fast-slow, FS) AVN reentrant echoes could be elicited with atrial and ventricular stimulation respectively. Discontinuous antegrade and retrograde AVN curves were present in both patients, as shown below: The earliest atrial activation during SF reentry was recorded at the His bundle electrogram, while during FS reentry it was recorded anterior and inferior to the coronary sinus ostium. A single radiofrequency (RF) application at the earliest atrial site during FS reentry eliminated both the FS echoes and the retrograde discontinuous curve, while maintaining a discontinuous antegrade curve (figure) and SF reentry (non sustained in one patient and sustained in the other patientl. In the latter patient, complete elimination of the slow pathway and SF reentry was achieved by further RF applications approximately 1 cm above the ablation site for FS reentry. Prevention of atypical AVN echoes does not necessarily abolish the typical form of AVN reentry. This suggests that the atypical form is not simply a “reverse” of the typical form of AVN reentry.