Pacemapping of the triangle of Koch: a simple method to reduce the risk of atrioventricular block during radiofrequency ablation of atrioventricular node reentrant tachycardia

Evaluation of the input site and characteristics of the antegrade fast pathway based on three-dimensional bi-atrial stimulus-ventricle mapping

Purpose

Previous studies examined the right atrial (RA) input site of the antegrade fast pathway (AFp) (AFpI). However, the left atrial (LA) input to the atrioventricular (AV) node has not been extensively evaluated. In this study, we created three-dimensional (3-D) bi-atrial stimulus-ventricle (St-V) maps and analyzed the input site and characteristics of the AFp in both the RA and LA.

Methods

Forty-four patients diagnosed with atrial fibrillation or WPW syndrome were included in this study. Three-dimensional bi-atrial St-V mapping was performed using an electroanatomical mapping system. Sites exhibiting the minimal St-V interval (MinSt-V) were defined as AFpIs and were classified into seven segments, four in the RA (F, S, M, and I) and three in the LA (M1, M2, and M3). By combining the MinSt-V in the RA and LA, the AFpIs were classified into three types: RA, LA, and bi-atrial (BA) types. The clinical and electrophysiological characteristics were compared.

Results

AFpIs were most frequently observed at site S in the RA (34%) and M2 in the LA (50%), and the BA type was the most common (57%). AFpIs in the LA were recognized in 75% of the patients. There were no clinical or electrophysiological indicators for predicting AFpI sites.

Conclusions

Three-dimensional bi-atrial St-V maps could classify AFpIs in both the RA and LA. AFpIs in the LA were frequently recognized. There were no significant clinical or electrophysiological indicators for predicting AFpI sites, and 3-D bi-atrial St-V mapping was the only method to reveal the precise AFp input site.

Coronary artery anatomy in peri-crux cordis area on computed coronary tomography angiography

Background

The peri-crux area is an anatomical structure of the heart. Unfortunately, important information on this area mainly derives from autopsy heart with a small, under-representative sample size, resulting in limited clinical applications. Furthermore, little has been done to standardize the definition of the peri-crux area on coronary computed tomography angiography (CCTA) images or to investigate coronary artery anatomy wherein potential values are attracting experienced inventional cardiologists in terms of the revascularization strategies. The current study aimed to identify the peri-crux cordis area and to observe coronary artery anatomical distributions in this area on CCTA.

Methods

A total of 1,006 consecutive patients undergoing CCTA exams were enrolled. We delineated the peri-crux cordis area based on the posterior interatrial sulcus, posterior interventricular sulcus (PIS), left and right posterior atrioventricular groove on the diaphragmatic surface of the heart. Then we observed the coronary artery distributions in the peri-crux cordis area in different sexes.

Results

We have defined the peri-crux cordis area according to the anatomical landmarks on the diaphragmatic surface of the heart on CCTA images. We have observed 8 coronary artery distributions in the peri-crux cordis area. Right dominance has 4 types (types 1-4); left, 1 type (type 0) and balanced, 3 types (types 5-7). Out of the 1,006 cases, the type 1 is commonest with 834 cases (82.9%). There are no statistically significant differences in terms of coronary dominances and coronary artery distributions in the peri-crux cordis area between sexes (P>0.05).

Conclusions

We have defined the peri-crux cordis area utilizing the anatomical landmarks of the heart on CCTA images, where 8 types of coronary artery distributions have been identified. The current study may provide interventional cardiologists with useful information on recognition of coronary artery dominance, use of collateral channels for revascularization of chronic total occluded lesions, and evaluation of prognosis in patients with coronary artery disease (CAD).

Incidence and Mechanism of Dislocated Fast Pathway in Various Forms of Atrioventricular Nodal Reentrant Tachycardia

BACKGROUND

The incidence and mechanism of the dislocated antegrade fast pathway (A-FP) were examined in various forms of atrioventricular nodal reentrant tachycardia (AVNRT).

METHODS AND RESULTS

To localize the A-FP, 5 atrial sites comprising the inferior coronary sinus ostium (CSOS), apex of the triangle of Koch (A-TOK), and 3 equidistant sites on the atrioventricular junction extending from A-TOK to CSOS (site S, M, and I) were pace mapped at 100 beats/min in 71 patients with slow-fast (n=49), fast-slow (n=7) and slow-intermediate (n=15) forms of AVNRT. The site with the shortest interval between the stimulus and His potential recorded at the A-TOK (shortest St-H) was defined as the A-FP site. The A-FP was located at A-TOK in 31 patients (nondislocated group), and inferior to A-TOK in 40 patients (site S in 26, M in 13, and I in one patient; dislocated group). There was no significant difference in the location of the A-FP among the 3 forms of AVNRT. Although the shortest St-H did not differ between groups, the St-H at A-TOK in the dislocated group was significantly longer than that in the nondislocated group. Additionally, the His potential preceding that of the A-TOK was observed more frequently inferior to the A-TOK in the dislocated group than in the nondislocated group, suggesting that the A-FP dislocation was accompanied by displacement of the His bundle.

CONCLUSIONS

Dislocated A-FP was frequently and uniformly observed among various forms of AVNRT, and is probably caused by inferior displacement of the entire atrioventricular node - His bundle apparatus.

Atrial activation during atrioventricular nodal reentrant tachycardia: Studies on retrograde fast pathway conduction

BACKGROUND

Detailed right and left septal mapping of retrograde atrial activation during typical atrioventricular nodal reentrant tachycardia (AVNRT) has not been undertaken and may provide insight into the complex physiology of AVNRT, especially the anatomic localization of the fast and slow pathways.

OBJECTIVES

The purpose of this study was to investigate the pattern of retrograde atrial activation during typical AVNRT by means of right-sided and left-sided septal mapping and implementation of pacing maneuvers for separating atrial and ventricular electrograms recorded during tachycardia.

METHODS

Twenty-two patients with slow-fast AVNRT were studied by means of simultaneous His-bundle recordings from the right and left sides of the septum. Patterns of retrograde atrial activation were recorded during tachycardia following specific pacing maneuvers and during right ventricular apical (RVA) pacing at the tachycardia cycle length.

RESULTS

The pattern of retrograde atrial activation could be mapped in 17 of 22 patients during AVNRT. In 9 (53%) patients, the earliest retrograde atrial activation was recorded on the left side of the septum, in 3 (17%) patients on the right side, and in 5 (29%) patients both right and left atrial septal electrograms occurred simultaneously. Stimulus to atrial electrogram times recorded during RVA pacing in 14 patients were 138.5 ms from the right His bundle, 134.5 ms from the left His bundle, and 148.0 ms from the ostium of the coronary sinus (P <.001). The predominant site of earliest retrograde atrial activation during RVA pacing was the left side of the septum (10 patients [71%]). Only 8 (57%) of 14 patients demonstrated concordance in the pattern of retrograde atrial activation during AVNRT and RVA pacing.

CONCLUSION

Earliest retrograde atrial activation during AVNRT is most often recorded on the left side of the septum. Breakthrough of atrial activation may be discordant from that observed during RVA pacing.

Transvenous radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia and its pitfalls: A rationale for cryoablation?

Today, radiofrequency (RF) catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is accompanied by a high success, a low recurrence, and a low complication rate. Despite the fact that over the years this technique has been refined, several shortcomings still remain. In this overview, the most important pitfalls in the treatment of AVNRT with RF energy are discussed. Cryotherapy has the ability to overcome some of them. Both ice mapping and cryo-adherence are important characteristics of this energy source to study prospective ablation sites before a definitive and irreversible lesion is created. Theoretically, this could lead to less applications with less tissue damage and abolish the risk for permanent conduction disturbances. The early experience with this technique will be described. Until now, it still has to be proven that in a large cohort of patients, cryotherapy is at least as effective, and safer than RF.

Classification and differential diagnosis of atrioventricular nodal re-entrant tachycardia

Recent evidence on atrioventricular nodal re-entrant tachycardia has identified several types of this common arrhythmia, with potential therapeutic implications. This article reviews the relevant new information, discusses the differential diagnosis of atrioventricular nodal re-entrant tachycardia, and summarizes the electrophysiological criteria for classification of the various forms of the arrhythmia.

Pace mapping of Koch's triangle reduces risk of atrioventricular block during ablation of atrioventricular nodal reentrant tachycardia

INTRODUCTION

Slow pathway (SP) ablation of AV nodal reentrant tachycardia (AVNRT) can be complicated by second- to third-degree AV block. We assessed the usefulness of pace mapping of Koch's triangle in preventing this complication.

METHODS AND RESULTS

Nine hundred nine consecutive patients undergoing radiofrequency ablation of AVNRT were analyzed. Group 1 (n=487) underwent conventional slow pathway ablation. Group 2 (n=422) underwent ablation guided by pace mapping of Koch's triangle, which located the anterogradely conducting fast pathway (AFP) based on the shortest St-H interval obtained by stimulating the anteroseptal, midseptal, and posteroseptal aspects of Koch's triangle. In group 2, AFP was anteroseptal in 384 (91%), midseptal in 33 (7.8%), and posteroseptal or absent in 5 (1.2%). In 32 of 33 patients with midseptal AFP, slow pathway ablation was performed strictly in the posteroseptal area. In 4 of 5 patients with posteroseptal or no AFP, retrograde fast pathway was ablated. Two patients refused ablation. Persistent second- to third-degree AV block was induced in 7 (1.4%) of 487 group 1 patients versus 0 (0%) of 422 group 2 patients (P=0.038). Ablation was successful in all patients in whom ablation was performed.

CONCLUSION

Pace mapping of Koch's triangle identifies patients in whom the AFP is absent or is abnormally close to the slow pathway. In these cases, guiding ablation helps to avoid AV block.