Propagation Mapping Wave Collision Correlates to the Site of Successful Ablation During Voltage Mapping in Atrioventricular Nodal Reentry Tachycardia

Transcatheter ablation of atrioventricular nodal reentry tachycardia in children and congenital heart disease in the era of 3D mapping

Atrioventricular nodal reentrant tachycardia (AVNRT) is a common supraventricular tachycardia in children and congenital heart disease (CHD) patients. Nowadays, in large enough children, chronic treatment for symptomatic and recurrent AVNRT episodes relies on transcatheter ablation. Indeed, many three-dimensional (3D) mapping strategies and ablation techniques have been developed and it helped to increase success rates and to reduce complications. Therefore, this study aimed to perform an updated comprehensive review of the available literature regarding contemporary management of AVNRT in children. A literature search was performed using Google Scholar, PubMed, Springer, Ovid, and Science Direct. We found that in recent times many investigations have demonstrated that 3D mapping systems allow to localize more precisely the ablation substrate, with minimal use of fluoroscopy. The most frequently employed mapping strategies are the low-voltage bridge strategy together with the search for the SP potential and the Sinus Rhythm Propagation Map with the identification of areas of Wave Collision or Pivot Points. For transcatheter ablation in pediatric settings, radiofrequency (RF) ablation was first used in the 1990s, while cryoablation was introduced in 2003 and nowadays represents the most used energy for AVNRT ablation in this population. Indeed, its specific features, such as reversible cryomapping, cryoadhesion and the precision in lesion delivery, made this technique very appealing to decrease complications and fluoroscopy time. As regards AVNRT in CHD patients, it represents the third most common form of arrhythmia in children with CHD. However, in this subgroup ablation remains challenging and experience limited, since anatomy may be atypical and the areas of ablation less predictable or less accessible.

Comparative utility of omnipolar and bipolar electroanatomic mapping methods to detect and localize dual nodal substrate in patients with atrioventricular nodal reentrant tachycardia

BACKGROUND

Catheter-based slow pathway modification (SPM) for atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed at empiric sites using anatomical landmarks and test ablation feedback within the triangle of Koch (TK). While studies have described more tailored techniques such as bipolar low voltage bridge (LVB) and wavefront collision identification, few have systematically compared the diagnostic yields of each and none have investigated whether omnipolar mapping technology provides incremental benefit. The objective of this study was to compare the utility of omnipolar and bipolar-derived qualitative and quantitative measurements in identifying and localizing dual AVN substrate in patients with versus without AVNRT.

METHODS

A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023.

RESULTS

Thirteen AVNRT cases (median age 16.1 years, 512 TK points) were compared to nine non-AVNRT controls (median age 15.7 years, 332 TK points). Among qualitative variables, an omnipolar activation vector pivot, defined as a ≥45 degree change in activation direction within the TK, had the highest positive (81%) and negative predictive values (100%) for identifying AVNRT cases and had a median distance of 1 mm from SPM sites. Among quantitative variables, the optimal discriminatory performance for successful SPM sites was observed using bipolar voltage restricted to a peak frequency >340 Hz (c statistic 0.75).

CONCLUSIONS

Omnipolar vector pivot analysis represents an automated, annotation-independent qualitative technique that is sensitive and specific for AVNRT substrate and co-localizes with successful SPM sites. Bipolar voltage quantitatively describes SP anisotropy better than omnipolar voltage, and the addition of peak frequency signal analysis further optimizes the selection of SPM sites.

A novel approach to typical atrioventricular nodal reentrant tachycardia with high-resolution mapping using the CARTO 3 cardiac mapping system

BACKGROUND

We hypothesized that high-resolution activation mapping during sinus rhythm (SR) in Koch's triangle (KT) can be used to describe the most delayed atrial potential around the atrioventricular node and evaluated whether ablation targeting of this potential is safe and effective for the treatment of patients with typical atrioventricular nodal reentrant tachycardia (AVNRT).

METHODS

We conducted a prospective, non-randomized, observational study using high-resolution activation mapping from the sinus node to KT with a PENTARAY or OCTARAY catheter using the CARTO 3 cardiac mapping system (Biosense Webster) during SR in 62 consecutive patients (22 men; age [mean ± standard deviation] = 55 ± 14 years) treated for typical AVNRT at our institution from August 2021 to March 2023.

RESULTS

In all cases, the most delayed atrial potential was observed near the His potential within KT. Ablation targeting of this potential helped successfully treat each case of AVNRT, with a junctional rhythm observed at the ablation site. Initial ablation was deemed successful in 55/62 patients (89%); in the remaining seven patients, lesion expansion resolved AVNRT. One procedural complication occurred, namely, a transient atrioventricular block lasting 45 s. One patient experienced a transient tachycardic episode by the 1-month follow-up, but no further episodes were noted up to the 1-year follow-up.

CONCLUSION

Activation mapping at KT during SR with the high-resolution CARTO system clearly revealed the most delayed atrial potential near the His potential within KT. Targeting this potential was a safe and effective treatment method for patients with typical AVNRT in our study.

Voltage and propagation mapping: New tools to improve successful ablation of atrioventricular nodal reentry tachycardia

INTRODUCTION

Mapping system is useful in ablation of atrioventricular nodal reentry tachycardia (AVNRT) and localization of anatomic variances. Voltage mapping identifies a low voltage area in the Koch triangle called low-voltage-bridge (LVB); propagation mapping identifies the collision point (CP) of atrial wavefront convergence. We conducted a prospective study to evaluate the relationship between LVB and CP with successful site of ablation and identify standard value for LVB.

MATERIALS AND METHODS

Three-dimensional (3D) maps of the right atria were constructed from intracardiac recordings using the ablation catheter. Cut-off values on voltage map were adjusted until LVB was observed. On propagation map, atrial wavefronts during sinus rhythm collide in the site representing CP, indicating the area of slow pathway conduction. Ablation site was selected targeting LVB and CP site, confirmed by anatomic position on fluoroscopy and atrioventricular ratio.

RESULTS

Twenty-seven consecutive patients were included. LVB and CP were present in all patients. Postprocedural evaluation identified standard cut-off of 0.3-1 mV useful for LVB identification. An overlap between LVB and CP was observed in 23 (85%) patients. Procedure success was achieved in all patient with effective site at first application in 22 (81%) patients. There was a significant correlation between LVB, CP, and the site of effective ablation (p = .001).

CONCLUSION

We found correlation between LVB and CP with the site of effective ablation, identifying a voltage range useful for standardized LVB identification. These techniques could be useful to identify ablation site and minimize radiation exposure.

High-density "APLE" Mapping-Activation, Propagation, Low Voltage, and Electrogram Evaluation with the HD Grid for Atrioventricular Nodal Re-entry Tachycardia Ablation

This is the first case series to evaluate high-density mapping of the triangle of Koch (TOK) using the HD Grid to guide slow-pathway ablation integrating activation, propagation (with wave collision), low-voltage signals, and atrial electrogram appearance. We will describe our technique and the results in this case series. Using three-dimensional mapping and the HD Grid, patients underwent high-density voltage mapping of the TOK. Ablation site selection was based on properties during sinus rhythm with late activation, at or above the propagation wave collision, over low voltage, and with appropriate electrogram appearance. Five patients underwent mapping of the slow pathway using the HD Grid. Their median age was 14 years, their median weight was 54.1 kg, and their median height was 161.5 cm. The TOK was mapped with the HD Grid for a median of 3 min. The procedure was successful in all patients using this technique. The median lesion number to the site of success was 3, with a median total number of cryotherapy lesions of 11. No radiation was used. There were no recurrences. Using activation, propagation wave, low voltage, and electrogram appearance when mapping for slow-pathway localization and ablation with the HD Grid can be successful, results in high-density maps, and is relatively faster.

Beyond Anatomy: Use of Sinus Propagation Mapping to Identify the Slow Pathway for Cryoablation in Pediatric Patients

Slow pathway modification via cryoablation is a common treatment of atrioventricular nodal re-entrant tachycardia (AVNRT) in pediatric patients. Sinus propagation mapping (SPM) is a tool that has been used to augment identification of the AVNRT slow pathway. We hypothesize that the use of SPM will decrease the total number of ablations performed and decrease the number of ablations until the slow pathway is successfully modified without a significant increase in procedure time. We conducted a retrospective review of patients who underwent cryoablation for AVNRT from August 2016 through March 2021. We excluded patients >21 years of age, those who underwent radiofrequency ablation; those with prior AVNRT ablation, additional pathways, or arrhythmias; and those with congenital heart disease. Out of 122 patients identified by the IMPACT database query, 103 met the inclusion criteria. Fifty-two patients (50.5%) had SPM completed during their procedures. The median number of ablations needed until successful slow pathway modification was two ablations in patients who underwent SPM and four ablations in the non-SPM group (P = .03). There was no significant difference in the total number of ablations between groups. The median total procedural time was longer in the SPM group (152 vs. 125 min; P = .01). SPM can be utilized to further improve the successful treatment of AVNRT with cryotherapy by lowering the number of ablations needed until successful slow pathway modification. However, the technique requires some additional time to collect sufficient data points to create the sinus map.

Catheter ablation of atrioventricular nodal reentrant tachycardia, when AVNRT presented as a fetus or infant

BACKGROUND

Atrioventricular nodal reentrant tachycardia (AVNRT) does not commonly present during infancy. Although relative safety of catheter ablation of AVNRT has been demonstrated in pediatrics, this procedure is rarely indicated in children <15 kg.

METHODS

Retrospective review of seven cases of AVNRT that presented in children younger than 1 year of age and required catheter ablation for definitive management. Electrophysiology (EP) study was planned with two or three catheters. Area of ablation determined by voltage mapping, propagation sinus wave collision and slow pathway potential location. Ablation performed with cryothermal energy. No fluoroscopy was used.

RESULTS

Presentation ranged from 36 weeks of gestation to 11 months of age. Two presented in fetal life and two in the neonatal period. The median age of ablation was 20 months (range 17-31 months). The median weight at ablation was 11.4 kg (range 8.9-14.9 kg). Median follow-up time was 16 months. All had typical AVNRT. The median tachycardia cycle length was 216 ms. 100% successful rate using cryoablation. No complications. No recurrence of tachycardia during the follow-up period.

CONCLUSION

Slow AV nodal pathway cryoablation may be safely performed, with good short and medium-term outcomes in patients under 15 kg.

Combination of slow pathway late activation maps and voltage gradient maps in guidance of atrioventricular nodal reentrant tachycardia cryoablation

BACKGROUND

The optimal strategy for electroanatomic mapping-guided cryoablation of atrioventricular nodal reentry tachycardia (AVNRT) remains unclear.

OBJECTIVE

The purpose of this study was to investigate the effectiveness of slow pathway late activation mapping (SPLAM) and voltage gradient mapping for AVNRT cryoablation.

METHODS

From June 2020 to February 2022, all consecutive patients with AVNRT underwent SPLAM to define the wave collision point and voltage gradient mapping to define the low-voltage bridge (LVB). Conventional procedures performed from August 2018 to May 2020 served as control.

RESULTS

The study and control groups comprised 36 patients (age 16.5 ± 8.2 years) and 37 patients (age 15.5 ± 7.3 years), respectively. Total procedural times were comparable, and acute success rates were 100% in both groups. Compared to controls, the number of cryomapping attempts (median 3 vs 5; P = .012) and cryoablation applications (median 1 vs 2; P <.001) were significantly lower in the study group. At median follow-up of 14.6 and 18.3 months, recurrence rates were 5.6% (2 patients) and 10.8% (4 patients) in the study and control groups (P = .402), respectively. Mapping of the Koch triangle took 11.8 ± 3.6 minutes, during which 1562 ± 581 points were collected. In SPLAM, wave collision points were defined and compatible with the final successful lesion sites in all patients, including those with multiple slow pathways. LVB could not be defined in 6 patients (16.7%), and LVB was not compatible with the final successful lesion in another 6 (16.7%).

CONCLUSION

For AVNRT cryoablation, SPLAM could effectively guide the localization of slow pathway ablation sites and was particularly beneficial in patients with multiple slow pathways.

Non-fluoroscopic Techniques for Catheter Ablation of Typical Atrioventricular Nodal Re-entry Tachycardia in a Pediatric Patient with Atypical Venous Anatomy

Catheter ablation of the slow pathway to the atrioventricular node is generally a safe and effective treatment for atrioventricular nodal re-entry tachycardia (AVNRT). However, congenital anomalies of the inferior vena cava and superior draining veins can limit traditional catheter approaches to the right heart from femoral venous access and distort local anatomy within the triangle of Koch, necessitating alternative electrophysiology (EP) mapping and ablation strategies. Despite the widespread availability of non-fluoroscopic 3-dimensional imaging systems, many providers still rely on venography to describe unusual cardiovascular anatomy and fluoroscopy to position EP catheters when mapping and ablating the slow pathway. Herein, we report our experience with a pediatric patient with inducible AVNRT and atypical venous anatomy in whom slow pathway ablation was performed successfully without the use of fluoroscopy. In addition, we describe the modification of a novel mapping technique for targeting the slow pathway for ablation.

Ripple Mapping: A precise tool for atrioventricular nodal reentrant tachycardia ablation

INTRODUCTION

Ablation for atrioventricular nodal reentrant tachycardia (AVNRT) classically utilizes evaluation of signal morphology within the anatomic region of the slow pathway (SP), which involves subjectivity. Ripple Mapping (RM) (CARTO-3© Biosense Webster Inc, Irvine, CA) displays each electrogram at its 3-dimensional coordinate as a bar changing in length according to its voltage-time relationship. This allows prolonged, low-amplitude signals to be displayed in their entirety, helping identify propagation in low-voltage areas. We set out to evaluate the ability of RM to locate the anatomic site of the slow pathway and assess its use in guiding ablation for AVNRT.

METHODS

Patients ≤18 yrs with AVNRT in the EP laboratory between 2017 and 2021 were evaluated. RM was performed to define region of SP conduction in patients from 2019-2021, whereas standard electro-anatomical mapping was used from 2017-2019. All ablations were performed using cryo-therapy. Demographics, outcomes and analysis of variance in number of test lesions until success were compared between groups.

RESULTS

A total 115 patients underwent AVRNT ablation during the study; 46 patients were in the RM group and 69 were in the control group. There were no demographic differences between groups. All procedures, in both groups, were acutely successful. In RM group, 89% of first successful lesions were within 4mm of the predicted site. There was significantly reduced variability in number of test lesions until success in the RM group (p=0.01).

CONCLUSIONS

RM is a novel technique that can help identify slow pathway location, allowing for successful ablation of AVNRT with decreased variability. This article is protected by copyright. All rights reserved.

Slow-pathway visualization by using voltage-time relationship: A novel technique for identification and fluoroless ablation of atrioventricular nodal reentrant tachycardia

BACKGROUND

Atrioventricular nodal reentrant tachycardia (AVNRT) is treatable by catheter ablation. Advances in mapping-system technology permit fluoroless workflow during ablations. As national practice trends toward fluoroless approaches, easily obtained, reproducible methods of slow-pathway identification, and ablation become increasingly important. We present a novel method of slow-pathway identification and initial ablation results from this method.

METHODS AND RESULTS

We examined AVNRT ablations performed at our institution over a 12-month period. In these cases, the site of the slow pathway was predicted by latest activation in the inferior triangle of Koch during sinus rhythm. Ablation was performed in this region. Proximity of the predicted site to the successful ablation location, complication rates, and patient outcomes were recorded. Junctional rhythm was seen in 40/41 ablations (98%) at the predicted site (mean, 1.3 lesions and median, 1 lesion per case). One lesion was defined as 5 mm of ablation. The initial ablation was successful in 39/41 cases (95%); in two cases, greater or equal to 2 echo beats were detected after the initial ablation, necessitating further lesion expansion. In 8/41 cases (20%), greater than one lesion was placed during initial ablation before attempted reinduction. Complications included one transient heart block and one transient PR prolongation. During follow-up (median, day 51), one patient had lower-extremity deep-vein thrombosis and pulmonary embolus, and one had a lower-extremity superficial venous thrombosis. There was one tachycardia recurrence, which prompted a redo ablation.

CONCLUSIONS

Mapping-system detection of late-activation, low-amplitude voltage during sinus rhythm provides an objective, and fluoroless means of identifying the slow pathway in typical AVNRT.