Classification, Electrophysiological Features and Therapy of Atrioventricular Nodal Reentrant Tachycardia

Relationship between the atrial-activation pattern around the triangle of Koch and successful ablation sites in slow-fast atrioventricular nodal reentrant tachycardia

Background

The precise details of atrial activation around the triangle of Koch (ToK) remain unknown. We evaluated the relationship between the atrial-activation pattern around the ToK and success sites for slow-pathway (SP) modification ablation in slow-fast atrioventricular reentrant tachycardia (AVNRT).

Methods

Thirty patients with slow-fast AVNRT who underwent successful ablation were enrolled. Atrial activation around the ToK during sinus rhythm was investigated using ultra-high-density mapping pre-ablation. The relationships among features of atrial-activation pattern and success sites were examined.

Results

Of 30 patients (22 cryoablation; 8 radiofrequency ablation), 26 patients had a collision site of two wavefronts of delayed atrial activation within ToK, indicating a success site. The activation-search function of Lumipoint software, which highlights only atrial activation with a spatiotemporal consistency, showed non-highlighted area on the tricuspid-annulus side of ToK. In 23 of the patients, a spiky potential was recorded at that collision site outside the Lumipoint-highlighted area. Fifteen cryoablation patients with a success site coincident with a collision site outside the Lumipoint-highlighted area had significantly more frequent disappearances of SP after initial cryoablation (46.7% vs. 0%, p = .029), fewer cryoablations (3.7 ± 1.8 vs. 5.3 ± 1.3, p = .045), and shorter procedure times (170 ± 57 vs. 228 ± 91 min, p = .082) compared to the seven cryoablation patients without such sites. Four patients had transient AV block by ablation inside the Lumipoint-highlighted area with fractionated signals, but no patient developed permanent AV block or recurrence post-procedure (median follow-up: 375 days).

Conclusions

SP modification ablation at the collision site of atrial activation of the tricuspid-annulus side along with a spiky potential could provide a better outcome.

Narrow Complex Tachycardia

This case report presents the electrocardiogram findings of a patient in their 50s with sudden onset, severe palpitations lasting for 2 hours.

Junctional Tachycardia

Junctional tachycardia (JT) is typically considered to have an automatic mechanism originating from the distal atrioventricular node. When there is 1:1 retrograde conduction via the fast pathway, JT would resemble the typical form of atrioventricular nodal re-entrant tachycardia (AVNRT). Atrial pacing maneuvers have been proposed to exclude AVNRT and suggest a diagnosis of JT. However, after excluding AVNRT, one should consider the possibility of an infra-atrial narrow QRS re-entrant tachycardia, which can exhibit features that resemble AVNRT as well as JT. Pacing maneuvers and mapping techniques should be performed to assess for infra-atrial re-entrant tachycardia before concluding that JT is the mechanism of a narrow QRS tachycardia. Distinguishing JT from typical AVNRT or infra-atrial re-entrant tachycardia has notable implications regarding the approach to ablation of the tachycardia. Ultimately, a contemporary review of the evidence on JT raises some questions as to the mechanism and source of what has traditionally been considered JT.

Quantitative assessment of the fast pathway in atrioventricular nodal reentrant tachycardia

BACKGROUND

Mathematical modelling has allowed calculation of the length of the slow and fast pathways in typical atrioventricular nodal reentrant tachycardia (AVNRT). The length of the slow pathway has been correlated with the measured length of the right inferior extension in human histologic specimens, but no histology data exist about the fast pathway.

METHODS

In preparations of cadaveric human hearts, the AV node was identified, and the site of the fast pathway was projected according to both existing evidence and results of our electroanatomic mapping. This permitted measurement of the length of the fast pathway as a limb of the tachycardia circuit.

RESULTS

Measurements of the length of the projected area of the fast pathway on histology specimens were performed in 8 hearts. The estimated length of the fast pathway was 39.6 ± 5.8 mm (range: 30.4-45.9 mm). These numbers are comparable to those produced by mathematical calculations of the length of the fast pathway.

CONCLUSIONS

Typical AVNRT uses a circuit from the AV node to the septal isthmus of an average size of 5-6 cm, confined within the pyramid of Koch.

Electrogram characteristics at successful cryoablation sites in slow-fast atrioventricular nodal reentrant tachycardia

PURPOSE

Cryoablation is a safe alternative to radiofrequency (RF) ablation for slow-fast atrioventricular reentrant tachycardia (AVNRT); however, optimal electrogram parameters for site selection remain unknown. We retrospectively investigated local electrograms for slow pathway (SP) modification in cryoablation.

METHODS

Forty-five consecutive patients with slow-fast AVNRT who underwent cryoablation using a 6-mm-tip catheter were enrolled. Electrogram parameters for sites of successful SP modification (success-sites) were investigated; these included the interval between atrial activation at His and the last deflection of SP potential, defined as the His(A)-SPP interval. In 8 patients, 3-dimensional mapping by multi-electrode catheter was performed pre-ablation for more detailed SP assessment.

RESULTS

Twenty-seven of 45 patients had successful SP modification by 1 cycle of freeze-thaw-freeze cryoablation at a single site with a low amplitude and fragmented SP potential. Among a total of 76 cryoablation sites in all patients, the His(A)-SPP interval at success-sites (45 sites) was significantly longer than that at unsuccess-sites (31 sites) (86 ± 9 vs.78 ± 10 msec, p < 0.0001). The AV amplitude ratio was not significantly different between success-and unsuccess-sites (0.21 ± 0.22 vs.0.25 ± 0.23, p = 0.429). The cutoff value of the His(A)-SPP interval for successful cryoablation was 82 msec with a sensitivity of 0.67 and specificity of 0.71 (AUC: 0.739; 95%CI: 0.626-0.852; p < 0.0001). Three-dimensional mapping in all 8 patients showed that sites with the most delayed atrial activation and the last deflection of the fragmented SP potential within the Koch's triangle coincided with success-sites.

CONCLUSION

A longer His(A)-SPP interval and fractionated SP potential were characteristics of successful cryoablation for SP modification in slow-fast AVNRT.

[Ablation of cardiac arrhythmias using a three-dimensional electro-anatomical mapping system in the Instituto Nacional Cardiovascular - INCOR]

Objective

To describe the initial experience in ablation of cardiac arrhythmias using 3D mapping at the Instituto Nacional Cardiovascular INCOR (Lima, Peru).

Methods

A retrospective descriptive study was carried out. During February 2020, data was collected from the medical records of all patients in whom ablation was performed using 3D mapping from July 2017 to December 2019. This procedure was performed in patients with symptomatic arrhythmia refractory to antiarrhythmic therapy.

Results

Data were collected from 123 patients (median age: 46 years, 64.2% male), who had a median time of illness of 6 years. Among the arrhythmias treated, 19% had atrial fibrillation, 17.5% atrial tachycardia, 17.5% idiopathic ventricular arrhythmias, 16.6% Wolf Parkinson White syndrome / Atrioventricular reentrant tachycardia, 11.1% ventricular arrhythmias of the His-Purkinje conduction system, 9.5% scar related ventricular tachycardia associated, 6.4% atrial flutter and 2.4% intranodal tachycardia. The median fluoroscopy time was 26 minutes. Ablation was acutely successful in 95.9% of cases, acute complications were observed in 4.8%, and recurrence-free survival during the first year of follow-up was 74%.

Conclusions

Our experience in ablation of cardiac arrhythmias using 3D mapping had a high acute success rate, low frequency of complications, and one-year recurrence-free survival of 74 %.

Arrhythmias and Conduction Disturbances in Autoimmune Rheumatic Disorders

Rhythm and conduction disturbances and sudden cardiac death are important manifestations of cardiac involvement in autoimmune rheumatic diseases (ARD), which have a serious impact on morbidity and mortality. While the underlying arrhythmogenic mechanisms are multifactorial, myocardial fibrosis plays a pivotal role. It accounts for a substantial portion of cardiac mortality and may manifest as atrial and ventricular arrhythmias, conduction system abnormalities, biventricular cardiac failure or sudden death. In patients with ARD, myocardial fibrosis is considered to be the hallmark of cardiac involvement as a result of inflammatory process or to coronary artery occlusive disease. Myocardial fibrosis constitutes the pathological substrates for reentrant circuits. The presence of supraventricular extra systoles, tachyarrhythmias, ventricular activity and conduction disturbances are not uncommon in patients with ARDs, more often in systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, inflammatory muscle disorders and anti-neutrophil cytoplasm antibody-associated vasculitis. In this review, the type, the relative prevalence and the underlying mechanisms of rhythm and conduction disturbances in the emerging field of cardiorheumatology are provided.

Delayed radiofrequency ablation efficacy in slow pathway ablation: a case report

BACKGROUND

The delayed effect of radiofrequency (RF) ablation was described in cases of accessory pathway and premature ventricular contraction ablation, as well as delayed atrioventricular (AV) block after slow pathway ablation.

CASE SUMMARY

We report a case of a female patient with AV nodal re-entry tachycardia (AVNRT), in whom the first electrophysiology study ended with acute failure of slow pathway ablation, despite using long steerable sheath, both right and left-sided ablation with >15 min of RF energy application and repeatedly achieving junctional rhythm. Six weeks afterwards, during scheduled three-dimensional electroanatomical mapping procedure, there was no proof of dual AV nodal conduction nor could the tachycardia be induced. Also, the patient did not have palpitations between the two procedures nor during the 12-month follow-up period.

DISCUSSION

This case illustrates that watchful waiting for delayed RF ablation efficacy in some cases of AVNRT ablation could be reasonable, in order to reduce the risk of complications associated with slow pathway ablation.

Antegrade slow pathway mapping of typical atrioventricular nodal reentrant tachycardia based on direct slow pathway capture

BACKGROUND

Radiofrequency (RF) ablation of typical atrioventricular nodal reentrant tachycardia (tAVNRT) is performed without revealing out the location of antegrade slow pathway (ASp). In this study, we studied a new electrophysiological method of identifying the site of ASp.

METHODS

This study included 19 patients. Repeated series of very high-output single extrastimulations (VhoSESts) were delivered at the anatomical slow pathway region during tAVNRT. Tachycardia cycle length (TCL), coupling interval (CI), and return cycle (RC) were measured and the prematurity of VhoSESts [ΔPM (= TCL - CI)] and the prolongation of RCs [ΔPL (= RC - TCL)] were calculated. Pacing sites were classified into two categories: (i) ASp capture sites [DSPC(+) sites], where two different RCs were shown, and ASp non-capture sites [DSPC(-) sites], where only one RC was shown. RF ablation was performed at DSPC(+) sites and/or sites with catheter-induced mechanical trauma (CIMT) to ASp.

RESULTS

DSPC(+) sites were shown in 13 patients (68%). RF ablation was successful in all patients without any degree of atrioventricular block nor recurrence. Total number of RF applications was 1.8 ± 1.1. Minimal distance between successful ablation sites and DSPC(+)/CIMT sites and His bundle (HB) electrogram recording sites was 1.9 ± 0.8 mm and 19.8 ± 6.1 mm, respectively. ΔPL of more than 92.5 ms, ΔPL/TCL of more than 0.286, and ΔPL/ΔPM of more than 1.565 could identify ASp with sensitivity of 100%, 91.1%, and 88.9% and specificity of 92.9%, 97.0%, and 97.6%, respectively.

CONCLUSIONS

Sites with ASp capture and CIMT were close to successful ablation sites and could be useful indicators of tAVNRT ablation.

[Supraventricular tachycardia - ECG interpretation and clinical management]

Supraventricular tachycardia (SVT) is a very common cause of hospital admission and its diagnostic and treatment may be difficult sometimes. While vagal maneuvers or intravenous adenosis administration during 12-lead ECG recording should be performed in hemodynamically stable patients for diagnosis and treatment, hemodynamically unstable patients should be carioverted immediately. The new ESC guideline (2019) on diagnosis and clinical management of SVT significantly upgrades catheter ablation and gives it a new preferential status. For example, in patients with symptomatic recurrence, atrioventricular nodal re-entrant tachycardia should be ablated due to the very low risk of AV block. Furthermore, catheter ablation should also be offered as first-line therapy to patients with reentrant and focal arrhythmias. The diagnosis and therapy of tachycardiomyopathy is of particular importance and treatment should incorporate the ablation of the underlying supraventricular tachycardia. The therapy of supraventricular tachycardia during pregnancy should be free of antiarrhythmic medication, especially in the first trimester. If ablation is necessary during pregnancy, only fluoroscopy-free mapping systems should be used. This review covers aspects of ECG diagnosis and guideline-based treatment of SVT.

Impact of Catheter Ablation for Atrial Arrhythmias on Repeat Cardioversion in Adults With Congenital Heart Disease

BACKGROUND

Atrial tachyarrhythmias (AAs) are the main source of morbidity and mortality in adult congenital heart disease (ACHD). Direct-current cardioversion (DCCV) is an effective method to acutely terminate AAs, but many patients require repeated DCCV. Little is known about the impact of radiofrequency catheter ablation (RFCA) of AAs on the incidence of repeated DCCV in patients with ACHD. The purpose of this study was to evaluate the impact of RFCA on the incidence of DCCV in patients with ACHD.

METHODS

A total of 157 patients with ACHD undergoing DCCV in our hospital from 2011 to 2018 (female n = 76 [48.4%], mean age 37.8 ± 12.5 y), were reviewed. The median follow-up period was 31.8 months (interquartile range 16.3-55.1 mo).

RESULTS

Out of the total of 157 patients, 102 (65.0%) underwent RFCA for AAs, and 55 (35.0%) were treated without RFCA. Successful RFCA with termination of AAs during ablation was 62.7%. More than one-half of the patients had complex forms of CHD (62.4%). During follow-up, 57 patients (55.9%) who had RFCA developed recurrence of AAs, and 36 patients (35.2%) underwent repeated DCCV. Thirty-three (60.0%) out of 55 patients without RFCA required repeated cardioversion. Compared with patients without RFCA, RFCA significantly reduced the need for repeated DCCV by 40% (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.23-0.80; P = 0.009). In multivariate analysis, successful RFCA was associated with reduced risk of DCCV (HR 0.41, 95% CI 0.19-0.92; P = 0.031).

CONCLUSIONS

AAs remain common despite RFCA in patients with ACHD. Nevertheless, RFCA is associated with a marked reduction in the need for repeated DCCV.

Left sided ablation for Atrioventricular Nodal Re-entrant Tachycardia: Frequency, Characteristics and Outcomes

Background

Left-sided ablation, targeting left inferior AV nodal extensions, is thought to be necessary for success in a small proportion of atrioventricular nodal re-entrant tachycardia (AVNRT) ablations; however Indian data are scarce in this regard.

Methods

Consecutive cases of AVNRT undergoing slow pathway ablation in a single centre over an 18-month period were retrospectively analyzed. Left-sided ablation at the posteroseptal mitral annulus was performed if right-sided ablation failed to abolish AVNRT.

Results

From January 2017 to June 2018, out of 215 consecutive supraventricular tachycardia (SVT) cases, 154 (71.6%) were AVNRT (47.1 ± 13.1 years, 46.1% male). Trans-septal ablation was required in 5 (3.2%) cases (mean age 48.8 ± 9.4 years; 4 female, 1 male); all with typical (slow-fast) form of AVNRT. Compared with cases needing only right-sided ablation, radiofrequency time (50.8 ± 16.9 vs. 9.9 ± 8.5 min; p = 0.005) and procedure time (166.0 ± 35.0 vs 79.6 ± 35.9 min; p = 0.004) were significantly longer for trans-septal cases, while baseline intervals and tachycardia cycle length were not significantly different. Junctional ectopy was seen in only 2 of the 5 cases during left-sided ablation, but acute success (non-inducibility) was obtained in 3 cases. There were no instances of AV block. Over mean follow-up of 12.2 ± 4.0 months, clinical recurrence of AVNRT occurred in one case, while others remained arrhythmia-free without medication.

Conclusion

Left-sided ablation was required in a small proportion of AVNRT ablations. Trans-septal approach targeting the posteroseptal mitral annulus was safe and yielded good mid-term clinical success.

A unified theory for the circuit of atrioventricular nodal re-entrant tachycardia

Atrioventricular nodal re-entrant tachycardia (AVNRT) is the most common regular tachycardia in the human, but its exact circuit remains elusive. In this article, recent evidence about the electrophysiological characteristics of AVNRT and new data on the anatomy of the atrioventricular node, are discussed. Based on this information, a novel, unified theory for the nature of the circuit of the tachycardia is presented.

Diagnosis and treatment of atrioventricular nodal reentrant tachycardia: a case report illustrating clinical management and ablation strategy

BACKGROUND

Atrioventricular nodal reentrant tachycardia (AVNRT) is a common supraventricular arrhythmia that is frequently encountered in an otherwise healthy patient population. Recent guidelines of the European Society of Cardiology underline the role of catheter ablation in the long-term management of these patients.

CASE SUMMARY

This case describes the clinical presentation and treatment options in a patient with typical slow/fast AVNRT, the most common subform of AVNRT, where antegrade conduction occurs over the slow pathway and retrograde conduction over the fast pathway. The ablation strategy in these patients is illustrated based on intracardiac recordings in combination with per-procedural three-dimensional imaging.

DISCUSSION

Atrioventricular nodal reentrant tachycardia is a common arrhythmia with good prognosis but significant impact on quality of life of affected patients. Catheter ablation should be considered early as it can be performed safely and with a very high success rate.

Fast pathway ablation in a patient with PR prolongation

The classical form of typical atrioventricular node reentrant tachycardia (AVNRT) is a "slow-fast" pathways tachycardia, and the usual therapy is an ablation of the slow pathway since it carries a low risk of atrioventricular (AV) block. In patients with long PR interval and/or living on the anterograde slow pathway, an alternative technique is required. We report a case of a 42-year-old lady with idiopathic restrictive cardiomyopathy, persistent atrial fibrillation status post pulmonary vein isolation, and premature ventricular complex ablation with a systolic dysfunction, who presented with incessant slow narrow complex tachycardia of 110 bpm that appeared to be an AVNRT. Her baseline EKG revealed a first-degree AV block with a PR of 320 ms. EP study showed no evidence of anterograde fast pathway conduction. Given this fact, the decision was to attempt an ablation of the retrograde fast pathway. The fast pathway was mapped during tachycardia to its usual location into the anteroseptal region, then radiofrequency ablation in this location terminated tachycardia. After ablation, she continued to have her usual anterograde conduction through slow pathway and the tachycardia became uninducible. In special populations with prolonged PR interval or poor anterograde fast pathway conduction, fast pathway ablation is the required ablation for typical AVNRT.

Should fast pathway ablation be reconsidered in typical atrioventricular nodal re-entrant tachycardia?

INTRODUCTION

Atrioventricular nodal re-entry tachycardia (AVNRT) is the most common, regular narrow-complex tachycardia. The established treatment is catheter ablation of the AV nodal slow pathway (SP). However, in a select group of patients with long PR intervals in sinus rhythm, SP ablation can lead to AV block due to the absence of robust anterograde conduction through the fast pathway (FP). This report aims to demonstrate that AV nodal FP ablation is a reasonable approach in patients with AVNRT and poor or absent anterograde FP conduction.

METHODS AND RESULTS

Standard electrophysiology study techniques were used in the electrophysiology laboratory. Catheter ablations were performed using radiofrequency energy. Mapping of intracardiac activation was performed with electroanatomical mapping systems. Outcomes were assessed acutely during the procedure and during routine clinical follow-up. Six patients with first-degree AV block and recurrent AVNRT who underwent ablation of their tachycardia at our institution are presented. One patient underwent ablation of AV nodal SP resulting in high-degree AV block necessitating pacemaker implantation. The remaining five patients underwent ablation of the AV nodal FP guided by electroanatomical mapping of the earliest atrial activation in tachycardia. These five had successful treatment of the tachycardia with preservation of anterograde AV nodal conduction. Mapping and ablation approach to eliminate retrograde FP conduction are described.

CONCLUSION

In select patients with AVNRT and poor anterograde FP conduction, retrograde FP ablation is reasonable and is less likely to result in AV block and pacemaker dependency.

Utility of low-dose adenosine triphosphate sensitivity in slow-fast atrioventricular nodal reentrant tachycardia

PURPOSE

Low-dose adenosine triphosphate (LD-ATP) is useful for diagnosing ATP-sensitive atrial tachycardia. However, the clinical implications of the sensitivity of LD-ATP in atrioventricular nodal reentrant tachycardia (AVNRT) still remain unknown. This study aimed to evaluate the mechanism of LD-ATP sensitivity in slow-fast AVNRT.

METHODS

We estimated the sensitivity of LD-ATP in slow-fast AVNRT by a 2-4-mg ATP intravenous injection during the tachycardia. We evaluated the atrial-His (A-H) interval, tachycardia termination mode, prevalence of a lower common pathway (LCP), and successful ablation site in slow-fast AVNRT with LD-ATP sensitivity. LCPs were defined as His-atrial interval differences of at least 5 ms between that during ventricular pacing at the tachycardia cycle length and that during the tachycardia.

RESULTS

Twenty-eight patients (mean age = 58 ± 11 years old, 18 females) with slow-fast AVNRT, who underwent catheter ablation of the antegrade slow pathway, were enrolled. Seventeen of 28 (61%) patients had LD-ATP sensitivity defined as termination of the tachycardia and/or a prolongation of the A-H interval of over 30 ms after an LD-ATP injection. The patients with LD-ATP sensitivity had a significantly higher prevalence of an LCP than those without (15/17 vs0/11, P < 0.0001). The successful ablation site in the LD-ATP sensitive group was significantly closer to the His bundle area than that in the LD-ATP nonsensitive group (13.3 ± 3.8 vs 20.5 ± 5.4 mm; distance to His bundle area in the left anterior oblique fluoroscopic view, P < 0.0001).

CONCLUSIONS

LD-ATP sensitivity in slow-fast AVNRT may suggest the existence of an LCP. The successful ablation site in patients with LD-ATP sensitivity could be closer to the His bundle region.

Catheter Ablation of Atrioventricular Nodal Re-entrant Tachycardia: Facts and Fiction

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Impact of Radiofrequency Ablation and Antiarrhythmic Medications on the Quality of Life of Patients with Supraventricular Tachycardias: Preliminary Validation of the Greek Version of the Umea22 (U22) Questionnaire

Objective

This study aims to (i) translate, culturally adapt, and preliminarily validate the arrhythmia-specific Umea22 (U22) questionnaire and (ii) assess the impact of radiofrequency (RF) ablation and medical treatment on the quality of life of patients with supraventricular tachycardias (SVTs).

Methods

A total of 140 patients with atrioventricular nodal re-entry tachycardia (AVNRT) and atrioventricular re-entry tachycardia (AVRT) were enrolled in the study. Of these, 100 patients underwent RF ablation (group A) and 40 patients were managed with antiarrhythmic medications (group B). Health-related quality of life (HRQoL) was assessed for both groups using the Short Form-36 Health Survey (SF-36) and the arrhythmia-specific Umea22 (U22) questionnaire at baseline and 3-month follow-up. Exploratory and confirmatory factor analyses were performed to assess the validity of the U22 questionnaire. Univariate comparisons of HRQoL scores between study timepoints and multivariate regression analyses adjusting for baseline confounders were conducted.

Results

The factor analysis of the U22 questionnaire yielded a six-factor model (“burden of spells”; “heart contractility”; “character of spells”; “general/non-specific feeling”; “other specific somatic symptoms”; “fear”) with acceptable fit results. Patients of group A showed significant improvement in all SF-36 and U22 scores at 3 months' follow-up compared to baseline (all p<0.05). Patients of group B presented deterioration of the total SF-36 score (p=0.001) and improvement of certain U22 measures, namely, well-being (p=0.004), heartbeat speed, and intensity during arrhythmia spells (p<0.0001 for both measures) at 3 months' follow-up, compared to baseline. Employment status, male sex, and urban residence emerged as important predictors.

Conclusion

The Greek version of the U22 questionnaire is a valid tool to assess SVT-related symptoms. RF ablation appears to exert more pronounced beneficial outcomes on HRQoL of patients with SVTs compared to medical treatment. Prompt referral of patients with SVTs to specialist centers may favorably affect their quality of life and should be encouraged.