Focal atrial tachycardias from the parahisian region: Strategies for mapping and catheter ablation

A novel endocardial activation-derived predictor for focal paraseptal atrial tachycardias: evidence from a multicenter cohort study

BACKGROUND

The electrocardiogram-based algorithm for predicting para-septal atrial tachycardia (PSAT) is limited by the significant overlaps in the P-wave morphology originating from various para-septal sites.

OBJECTIVE

The aim of this study was to investigate the endocardial activation characteristics of PSAT and to seek an endocardial activation-derived predictor for the ablation site.

METHODS

Forty-four patients (11 males, average 62.6±14.7 years) with PSAT ablation in four tertiary medical centers were assigned into three groups according to the ablation site: right atrial (RA) para-Hisian region (Group 1, n=10), the noncoronary cusp (NCC) (Group 2, n=13) and left atrial (LA) para-septal areas (Group 3, n=21). Multiple-chamber activation mapping was performed guided by a 3D navigation system. The discrepancies in the earliest activation time between two of three chambers (ΔRA-LA, ΔRA-NCC and ΔLA-NCC) were calculated in each group and used for pairwise comparisons.

RESULTS

There was significant difference in ΔRA-LA, ΔRA-NCC, and ΔLA-NCC compared among three groups. ΔRA-LA was the only parameter which could consistently predict the ablation site of PSAT with good accuracy (AUC 1.000, sensitivity 100%/ specificity 100%, and cut-off value 7ms for predicting right para-Hisian or NCC ablation; AUC 0.974, sensitivity 92.3%/specificity 95.2%, and cut-off value -4 ms for predicting NCC or left para-septal ablation). Based on two cut-off values, A two-step algorithm was developed to predict the ablation site of PSAT with positive predictive value of 95.4% and negative predictive value of 97.0%.

CONCLUSIONS

ΔRA-LA is a useful endocardial activation-derived parameter for predicting the successful ablation site of PSAT.

Focal atrial tachycardias originating from the aorta-mitral continuity: Anatomical and electrophysiological characteristics

BACKGROUND

The aorta-mitral annulus conjunction (AMC) is an uncommon site of origin of focal atrial tachycardias (ATs). Hence, the electrophysiological and ablation target characteristics are poorly described.

OBJECTIVE

The purpose of this study was to describe the characteristics of AMC AT in detail.

METHODS

The study enrolled 650 patients with AT, 21 (3.2%) of whom had AT originating from the AMC. A comprehensive evaluation, including electrocardiography, electrophysiology study, computed tomography scan, and intracardiac echocardiography, was performed.

RESULTS

The majority (90.5%) of ATs occurred spontaneously. The mean age of this group was 48.9 ± 21.6 years, with 12 being female (57.1%). Seventeen patients had a typical biphasic P wave with a prominent positive component. The earliest activation site in the right atrium was near the His bundle, with average activation -10.3 ± 6.0 ms preceding the P wave. The successful ablation targets were distributed as follows: 1 case at 9 o'clock, 6 cases at 10 o'clock, 7 cases at 11 o'clock, 6 cases at 12 o'clock, and 1 case in the left coronary cusp. The local AMC potential differed from the commonly perceived annular potential and was characterized by a large A and a small V (atrial-to-ventricular ratio > 1). The angle of encroachment on the left atrial anterior wall, compressed by the left coronary cusp, was significantly smaller in the AMC AT group than in the control group, which may have contributed to the arrhythmia substrate (141.7° ± 11.5° vs 155.2° ± 13.9°; P = .026).

CONCLUSION

A new strategy for mapping AMC ATs has been introduced. The ablation target should have an atrial-to-ventricular ratio of >1.

Discrimination of atypical atrioventricular nodal reentrant tachycardia from atrial tachycardia by the V-A-A-V response

INTRODUCTION

The electrophysiological discrimination between fast-slow (F/S-) atrioventricular (AV) nodal reentrant tachycardia (NRT) and atrial tachycardia (AT) originating from the interatrial septum remains challenging. While a V-A-A-V response may occur immediately after ventricular induction or entrainment of either tachycardia, the electrophysiological dissimilarities in that response between the two tachycardias remain unclear. The purpose of this study was to identify a diagnostic indicator discriminating F/S-AVNRT from AT by examining the difference in the V-A-A-V response between the two tachycardias.

METHODS

This retrospective study included 17 patients with F/S-AVNRT [7 with common-form F/S-AVNRT using a typical slow pathway (SP) and 10 with superior type F/S-AVNRT using a superior SP] and 10 patients with reentrant AT. All 27 patients presented with long RP supraventricular tachycardia and an initial V-A-A-V response upon ventricular induction or entrainment. The V-A-A-V response in patients with F/S-AVNRT was due to dual atrial responses. We measured the interval between the first (A1) and second atrial electrogram (A2) of V-A-A-V and calculated ΔAA by subtracting A1-A2 from the tachycardia cycle length.

RESULTS

V-A-A-V responses were observed most often upon ventricular induction of F/S-AVNRT (6±5 times) as well as AT (6±6 times; P = 0.87). The V-A-A-V response upon ventricular entrainment was observed in a single patient with F/S-AVNRT versus 10 all patients with AT (P<0.001). ΔAA ranged between -80 and 228 ms in F/S-AVNRT and between -184 and 26 ms in AT. A ΔAA >26 ms predicted a diagnosis of F/S-AVNRT with a 76% sensitivity and 100% specificity, while a ΔAA ←80 ms predicted a diagnosis of AT with a 50% sensitivity and 100% specificity.

CONCLUSIONS

ΔAA is a useful, confirmatory, diagnostic indicator of F/S-AVNRT versus AT associated with the V-A-A-V response. This article is protected by copyright. All rights reserved.

Outcomes of Different Ablation Approaches for Para-Hisian Accessory Pathway and Ablation Safety at Each Site

Background

This study describes the electrophysiologic characteristics of the para-hisian accessory pathway (AP), the outcome of different ablation approaches, and ablation safety at different sites.

Method

A total of 120 patients diagnosed as para-hisian AP were included in this study. The electrophysiologic characteristics and outcomes at different ablation sites were analyzed.

Results

In total, 107 APs and 13 APs were diagnosed as right anteroseptal (RAS) and right midseptal (RMS), respectively. The significant ECG difference between RAS and RMS was lead III, which mainly manifested as positive and negative delta waves, respectively. Catheter trauma to AP was recorded in 21 of 120 (17.5%) patients. The recurrence rate of direct ablation at the “bumped” sites was higher than the conventional ablation method (37.5 vs. 14.1 %, p = 0.036). For RAS APs, there was no significant difference in the success rate between the inferior vena cava (IVC) and superior vena cava (SVC) approaches (76.6 vs. 73.3%, p = 0.63). The RAS was separated into three regions: (1) Site 1: superior part above the real “His” recorded site with far-field “His” potential; (2) Site 2 (true para-hisian): the site with near-field “His” potential; and (3) Site 3: inferior part below the biggest real “His” with far-field “His” potential. Mid-septal was defined as an area that is bounded anteriorly by His recording location and posteriorly by the roof of coronary sinus (CS) ostium. The incidence of atrioventricular (AV) conduction injury at different sites was as follows: 3 of 6 (50%) at Site 2, 4 of 13 (30.8%) at RMS, 7 of 34 (20.6%) at Site 3, and 3 of 46 (6.5%) at Site 1. Even if ablation was performed at the atrial side of the para-hisian region, the right bundle branch block (RBBB) was caused in 6 patients (5%).

Conclusion

Ablation via IVC or SVC was comparative for para-hisian APs, but not for the noncoronary cusp (NCC) approach. The AV conduction injury risk ranks as follows: Site 2 > RMS > Site 3 > Site 1. RBBB could be caused while ablating at the atrial side, which could further demonstrate the His bundle longitudinal dissociation theory.

Efficacy of Catheter Ablation From the Non-Coronary Aortic Cusp of Verapamil-Sensitive Atrial Tachycardia Arising Near the Atrioventricular Node

BACKGROUND

Efficacy of catheter ablation from the non-coronary aortic cusp (NCC) of verapamil-sensitive atrial tachycardia arising near the atrioventricular node (AVN-AT) has yet to be fully clarified.

OBJECTIVE

We elucidated the determinant of an effective AVN-AT ablation from the NCC.

METHODS

After identifying the earliest atrial activation site (EAAS) during tachycardia, the direction of the slow conduction zone (SCZ) of reentry circuit was identified by demonstrating manifest entrainment in 26 AVN-AT patients. Catheter ablation was initially performed from the NCC irrespective of the local activation time. If the NCC ablation was ineffective, catheter ablation was performed targeting the SCZ entrance. Then the anatomical relationship between the SCZ and successful ablation site was elucidated.

RESULTS

NCC catheter ablation terminated AVN-AT in 14 patients (NCC Group) but not in 12 (Non-NCC Group). Catheter ablation targeting the SCZ entrance terminated all Non-NCC Group ATs. The local activation time at the NCC relative to the EAAS did not differ between the NCC and Non-NCC Groups (10.1±6.5 vs. 11.2±4.8 msec, p=0.6333). The direction of the SCZ was posterior to the EAAS in all NCC Group patients, however, it was postero-lateral (n=5) and lateral to the EAAS (n=7) in the Non-NCC Group, suggesting that the SCZ existed in the direction of the NCC in NCC Group but was away from the NCC in Non-NCC Group.

CONCLUSION

A close proximity between the NCC and SCZ of the reentry circuit, but not the local activation time at the NCC, determined the efficacy of NCC catheter ablation in AVN-ATs.

Intracardiac Echocardiography to Guide the Ablation of Parahisian Arrhythmias

Arrhythmias from the perinodal region have been described for accessory pathways (APs), atrial tachycardias (AT), premature ventricular complexes (PVCs), and ventricular tachycardia (VT). The parahisian (PH) region encompasses anatomic structures that include the atrioventricular (AV) node and His-Bundle (HB). These locations are at high-risk for inducing AV block during catheter ablation in the electrophysiology laboratory. PH arrhythmias were initially defined as having sites of origin within 10 mm of the largest HB potential (>0.1 mV) recording site, but more recent definitions have included any site that has an HB potential at the ablation site. Intracardiac echocardiography (ICE) use offers real-time visualization of the catheter tip-to-tissue contact and can monitor for acute complications during atrial and ventricular procedures. ICE also enables a broad appreciation of real-time cardiac structures, which is invaluable in navigating the complex anatomy of the PH region.

[Catheter ablation of supraventricular tachycardia]

Supraventricular tachycardias (SVT) are common, with atrioventricular nodal reentry tachycardias (AVNRT) being the most common paroxysmal supraventricular tachycardia. The pathophysiological understanding and the catheter ablation of SVTs have developed steadily in recent years. For example, dividing AVNRT into "typical" and "atypical" depending on the HA-, VA-interval and AH/HA ratio is recommended. Because of higher rates of recurrences after cryoablation, radiofrequency ablation has prevailed in AVNRT. The current ESC guidelines for SVTs recommend the ablation of accessory pathways in asymptomatic high-risk patients and it is now a Class I recommendation. There is no recommendation for the access in left-sided accessory pathways. However, a transseptal compared to transaortic approach seems more promising in acute success. The use of a three-dimensional (3D) mapping system leads to a reduction of the fluoroscopy times and procedure duration. Ablation of focal atrial tachycardia remains challenging despite the use of 3D electroanatomical mapping systems. However, new technologies such as high-density (HD) multipoint mapping systems can be helpful. HD mapping systems also allow a better understanding of left and right atrial macroreentry tachycardia after previous ablation or cardiac surgery and in primary nature. However, in all technological advances, a proficient understanding of the basic techniques in electrophysiology, such as entrainment mapping, is mandatory.

Focal atrial tachycardia ablation: Highly successful with conventional mapping

BACKGROUND/OBJECTIVE

Radiofrequency catheter ablation (RFCA) of focal atrial tachycardia (FAT) traditionally is guided by conventional endocardial mapping of earliest atrial activation; however, more recently electro-anatomical mapping is heralded as a more effective, albeit more expensive, tool to guide ablation. Herein we present the results of conventional mapping-guided RFCA. Apropos, we conducted a literature search of studies reporting > 10 FAT patients submitted to RFCA.

METHODS AND RESULTS

Conventional mapping-guided RFCA, performed in 63 FAT patients (aged 42.4 + 17.3 years; 14 with incessant tachycardia and 12 with tachycardiomyopathy (TCM)), was successful in 61 (96.8%) patients, applied for single foci in 59 (93.7%) and two foci in 4 patients, right (n = 46) or left sided (n = 17). The earliest atrial activation time at the ablation site was 41.3 ± 16.2 ms. Fluoroscopy time averaged 27.3 + 18.7 min, and procedure lasted 2.6 + 1.7 h. Complications occurred in two patients (sinus pauses in one needing a pacemaker and a large inguinal hematoma in one). Over 29.0 + 22.9 months, four patients (6.5%) had recurrences, of whom three were successfully re-ablated. All patients with TCM showed gradual improvement to normalization over 4-6 months. Literature search showed that RFCA success is equally high when guided with either conventional (88.5%) or electro-anatomical mapping (90%) with similar recurrences (9.6% vs. 9.5%).

CONCLUSION

Conventional mapping-guided RFCA of FAT had high success (96.8%) with low complication (3.2%) and recurrence rates (6.5%). TCM was fully reversible. These results are comparable to those achieved with the more expensive electro-anatomical mapping, which may be reserved for more complex cases or for those failing the conventional approach.