Selective atrial vagal denervation guided by spectral mapping to treat advanced atrioventricular block

Cardioneuroablation: Three different approaches

Cardioneuroablation (CNA) is an emerging therapy for patients with vasovagal syncope with predominant cardioinhibitory responses. The procedure targets the neuromyocardial connections localized in specific regions of the right and left atrium as well as the adjacent ganglionated plexi (GP) providing parasympathetic innervation to the sinus and atrioventricular nodes. The target regions for CNA can be determined with various techniques, which result in heterogenous procedural approaches and endpoints in different centers specialized in this procedure. In this review we summarize the rationale and details of the procedural approach for three different techniques for CNA, namely: CNA controlled by extra-cardiac vagal stimulation, CNA guided by analysis of fractionated electrograms, and an anatomical approach to CNA.

A study on the therapeutic effect of zero-ray cardiac autonomic ganglion ablation on vasovagal syncope in a special occupational young population

Background

This study aims to evaluate the safety and efficacy of zero-ray radiofrequency ablation of the cardiac autonomic ganglionic plexus (GP) for treating vasovagal syncope (VVS) in young individuals undergoing high-intensity physical training.

Methods

We retrospectively analyzed data from 35 young individuals with recurrent syncope (≥3 syncopal episodes within the year prior to the procedure) who underwent GP ablation at our hospital between May 2021 and January 2023. Among them, 33 (94.3%) were male, with a mean age of 22.7 ± 4.6 years. Systemic diseases and/or organic heart conditions that could cause syncope were excluded through comprehensive examinations upon admission. GP ablation was performed in patients with a positive upright tilt test. During the procedure, zero-ray septal puncture was guided by intracardiac ultrasound, and the GP was localized using the anatomical approach (AA) as the ablation target. The ablation endpoint was defined as an increase in heart rate to approximately 90 beats per minute. The safety and efficacy of the procedure were assessed by comparing preoperative and postoperative data, including heart rate, sinus node recovery time, atrioventricular (AV) Wenckebach point, heart rate variability (HRV), deceleration capacity of the heart (DC), and the occurrence of arrhythmias.

Results

No intraoperative or postoperative complications were observed with zero-ray intracavitary ultrasound-guided GP ablation. Postoperatively, the sinus node recovery time and AV Wenckebach point were significantly shorter compared to preoperative values (P < 0.001). Both the postoperative mean ECG heart rate and the 12-month postoperative Holter mean heart rate were significantly higher than preoperative levels (P < 0.001). Additionally, sDANN-24, rMSSD, and deceleration capacity (DC) were significantly reduced postoperatively (P < 0.001). The follow-up period ranged from a minimum of 15 months to a maximum of 35 months. Within one year after surgery, two cases experienced a single episode of syncope, and one case reported a single episode of a syncopal premonitory aura. In the patient with a syncopal premonitory aura, outpatient ECG and Holter monitoring showed no abnormalities. The patient who experienced syncope was readmitted for further evaluation, including ECG, Holter monitoring, and an upright tilt test, which was negative. Two postoperative cases (one with a syncopal premonitory aura and one without syncope) exhibited second-degree type II AV block on Holter monitoring, which occurred during nocturnal sleep. Despite this, both groups were able to continue high-intensity physical training with significant symptomatic improvement.

Conclusions

Zero-ray cardiac GP ablation is a radiation-free, minimally invasive, safe, and effective treatment for young VVS patients undergoing high-intensity physical training.

A new stepwise approach to minimize phrenic nerve injury during cryoballoon pulmonary vein isolation

BACKGROUND

A phrenic nerve injury (PNI) during cryoballoon (CB) pulmonary vein isolation (PVI) continues to represent a limitation of this technique. The objective of this study was to develop a novel technique with the aim of reducing the incidence of PNI.

METHODS

We performed a retrospective analysis of data from two hospitals in patients with symptomatic, drug-resistant atrial fibrillation (AF) over 7 years to evaluate the incidence and clinical characteristics of PNI during cryoballoon PVI. Patients in the intervention group were treated with a new technique consisting of the following consecutive steps: (A) phrenic nerve stimulation near stimulation threshold instead of 10 V stimulation; (B) advanced ablation to the right superior pulmonary vein (PV) using a pre-freezing technique; (C) "pulling away" of the CB after vein isolation and/or after reaching - 40 °C for both right PVs. Two subtypes of PNI were studied: persistent (no recovery to discharge) and transient (recovery to discharge) PNI.

RESULTS

Nine hundred patients with a mean age of 62.3 (± 10.9) years (38% female) were analyzed. Transient PNI occurred in 8/250 patients (3.2%) in the intervention group compared to 39/750 patients (6%) in the control group (p = 0.09). Persistent PNI occurred in one patient (0.4%) in the intervention group compared to 18 (2.8%) in the control group (p = 0.03). Any PNI occurred in 9 patients in the intervention group (3.6%) compared to 57 patients (8.8%) in the control group (p = 0.008).

CONCLUSION

In this retrospective analysis, a new cryo-PVI technique significantly reduces the incidence of PNI, particularly persistent PNI.

Ablation of myocardial autonomic ganglion plexus in the treatment of bradyarrhythmia A one-arm interventional study

OBJECTIVES

To study the complications and effectiveness of the treatment of chronic arrhythmias with cardiac Ganglion Plexus (GP) ablation, and to explore the value of the treatment of chronic arrhythmias with GP ablation.

METHODS

This study was a one-arm interventional study of patients from the first hospital of Xinjiang Medical University and the People's Hospital of Xuancheng City admitted (09/2018-08/2021) because of bradyarrhythmia. The left atrium was modeled using the Carto3 mapping system. The ablation endpoint was the absence of a vagal response under anatomically localized and high-frequency stimulation guidance. Postoperative routine follow-up was conducted. Holter data at 3-, 6-, and 12-months were recorded.

RESULTS

Fifty patients (25 male, mean age 33.16 ± 7.89 years) were induced vagal response by either LSGP, LIGP, RAGP, or RIGP. The heart rate was stable at 76 bpm, SNRT 1.092s. DC, DR, HR, SDNN, RMSSD values were lower than that before ablation. AC, SSR, TH values were higher than those before ablation, mean heart rate and the slowest heart rate were significantly increased. There were significant differences in follow-up data between the preoperative and postoperative periods (all p < 0.05). All the patients were successfully ablated, and their blood pressure decreased significantly. No complications such as vascular damage, vascular embolism and pericardial effusion occurred.

CONCLUSIONS

Left Atrial GP ablation has good long-term clinical results and can be used as a treatment option for patients with bradyarrhythmia.

Cardioneuroablation for vasovagal syncope: insights on patients' selection, centre settings, procedural workflow and endpoints-results from an European Heart Rhythm Association survey

AIMS

Cardioneuroablation (CNA) is a catheter-based intervention for recurrent vasovagal syncope (VVS) that consists in the modulation of the parasympathetic cardiac autonomic nervous system. This survey aims to provide a comprehensive overview of current CNA utilization in Europe.

METHODS AND RESULTS

A total of 202 participants from 40 different countries replied to the survey. Half of the respondents have performed a CNA during the last 12 months, reflecting that it is considered a treatment option of a subset of patients. Seventy-one per cent of respondents adopt an approach targeting ganglionated plexuses (GPs) systematically in both the right atrium (RA) and left atrium (LA). The second most common strategy (16%) involves LA GP ablation only after no response following RA ablation. The procedural endpoint is frequently an increase in heart rate. Ganglionated plexus localization predominantly relies on an anatomical approach (90%) and electrogram analysis (59%). Less utilized methods include pre-procedural imaging (20%), high-frequency stimulation (17%), and spectral analysis (10%). Post-CNA, anticoagulation or antiplatelet therapy is prescribed, with only 11% of the respondents discharging patients without such medication. Cardioneuroablation is perceived as effective (80% of respondents) and safe (71% estimated <1% rate of procedure-related complications). Half view CNA emerging as a first-line therapy in the near future.

CONCLUSION

This survey offers a snapshot of the current implementation of CNA in Europe. The results show high expectations for the future of CNA, but important heterogeneity exists regarding indications, procedural workflow, and endpoints of CNA. Ongoing efforts are essential to standardize procedural protocols and peri-procedural patient management.

Ganglionated Plexus Ablation Procedures to Treat Vasovagal Syncope

Vasovagal syncope (VVS) refers to a heterogeneous group of conditions whereby the cardiovascular reflexes normally controlling the circulation are interrupted irregularly in response to a trigger, resulting in vasodilation, bradycardia, or both. VVS affects one-third of the population at least once in their lifetime or by the age of 60, reduces the quality of life, and may cause disability affecting certain routines. It poses a considerable economic burden on society, and, despite its prevalence, there is currently no proven pharmacological treatment for preventing VVS. The novel procedure of ganglionated plexus (GP) ablation has emerged rapidly in the past two decades, and has been proven successful in treating syncope. Several parameters influence the success rate of GP ablation, including specific ablation sites, localization and surgical techniques, method of access, and the integration of other interventions. This review aims to provide an overview of the existing literature on the physiological aspects and clinical effectiveness of GP ablation in the treatment of VVS. Specifically, we explore the association between GPs and VVS and examine the impact of GP ablation procedures as reported in human clinical trials. Our objective is to shed light on the therapeutic significance of GP ablation in eliminating VVS and restoring normal sinus rhythm, particularly among young adults affected by this condition.

Twenty-five years of research on syncope

Over the last 25 years, the Europace journal has greatly contributed to dissemination of research and knowledge in the field of syncope. More than 400 manuscripts have been published in the journal. They undoubtedly improved our understanding of syncope. This symptom is now clearly differentiated from other forms of transient loss of consciousness. The critical role of vasodepression and/or cardioinhibition as final mechanisms of reflex syncope is emphasized. Current diagnostic approach sharply separates between cardiac and autonomic pathways. Physiologic insights have been translated, through rigorously designed clinical trials, into non-pharmacological or pharmacological interventions and interventional therapies. The following manuscript is intended to give the reader the current state of the art of knowledge of syncope by highlighting landmark contributions of the Europace journal.

Long-Term Outcome of Cardiac Denervation Procedures: The Anatomically Guided Septal Approach

BACKGROUND

Functional bradycardia is a challenging condition that affects a healthy population. Ganglionated plexus ablation has emerged as a therapeutic alternative to avoid a pacemaker.

OBJECTIVES

The purpose of this study is to evaluate long-term effects of anatomically guided cardiac denervation.

METHODS

This is a prospective longitudinal study that included 36 patients with symptomatic functional bradycardia. Electroanatomic reconstruction of both atria was carried out, and the main septal ganglionated plexi were anatomically located and targeted.

RESULTS

Ablation endpoints were: 1) heart rate increment; 2) Wenckebach cycle length shortening; and 3) atrio-Hisian (AH) interval shortening. A sinus node denervation was obtained in all patients with an increment of 21.6% in the mean heart rate. All patients presented a negative atropine test after ablation. Twenty-eight (77.7%) patients presented immediate sings of atrioventricular node denervation, with a shortening of 15.6% of mean Wenckebach cycle length and 15.9% of the mean AH interval. All heart rate variability parameters showed a significant reduction after 12 months, enduring after 18 months. Thirty (83.3%) patients remained free of events after a mean follow-up of 52.1 ± 35.2 months. One patient (2.77%) presented acute sinus node artery occlusion during ablation with persistent sinus dysfunction and had a pacemaker implantation; 3 (8.3%) other patients evolved with sinus tachycardia, and 4 (11.1%) patients presented syncope recurrence during follow-up, 3 (8.3%) of them requiring a pacemaker implantation. No other tachyarrhythmia was observed.

CONCLUSIONS

The anatomically guided septal approach is an effective technique for syncope prevention, promoting long-lasting autonomic changes. No significant proarrhythmia effect has been observed during the long-term follow-up.

Bradyarrhythmia in a marathonist: Cardiac vagal denervation as alternative treatment

Although not routinely used, cardioneuroablation or modulation of the cardiac autonomic nervous system has been proposed as an alternative approach to treat young individuals with enhanced vagal tone and significant atrioventricular (AV) disturbances. We report the case of a 42-year-old athlete with prolonged ventricular pauses associated with sinus bradycardia and paroxysmal episodes of AV block (maximum of 6.6 s) due to enhanced vagal tone who was admitted to our hospital for pacemaker implantation. Cardiac magnetic resonance and stress test were normal. Although he was asymptomatic, safety concerns regarding possible neurological damage and sudden cardiac death were raised, and he accordingly underwent electrophysiological study (EPS) and cardiac autonomic denervation. Mapping and ablation were anatomically guided and radiofrequency pulses were delivered at empirical sites of ganglionated plexi. Modulation of the parasympathetic system was confirmed through changes in heart rate and AV nodal conduction properties associated with a negative cardiac response to atropine administration. After a follow-up of nine months, follow-up 24-hour Holter revealed an increase in mean heart rate and no AV disturbances, with rare non-significant ventricular pauses, suggesting that this technique may become a safe and efficient procedure in this group of patients.

Initial Experience with Fractionation Mapping in the Identification of Vagal Ganglionated Plexus During Cardioneuroablation

This is a series case report of five symptomatic patients presented with diagnosis of sinus bradycardia, first and second degrees atrioventricular (AV) blocks, that were referred to pacemaker implantation. During the screening, a functional cause for the bradycardia and AV blocks were documented by treadmill stress test, 24-hour Holter monitoring and atropine test. After the confirmation of the diagnosis, patients were submitted to cardioneuroablation on an anatomical basis supported by a tridimensional electroanatomical fractionation mapping software. The technique and the acute and short-term results of the cardioneuroablation are described.

Clinical analysis of cardiac autonomic ganglion plexus ablation for bradyarrhythmia: Research protocol for an intervention study

OBJECTIVE

This study aimed to explore the safety and effectiveness of selective cardiac autonomic ganglion plexus (GP) ablation on patients with bradyarrhythmia. The heart is controlled by its own intrinsic and central autonomic nerves. Increased cardiac vagal tone leads to sinus node dysfunction and atrioventricular conduction disorders, resulting in bradyarrhythmia. Pacemaker implantation can relieve the symptoms of arrhythmia caused by bradycardia, but it is not easy for patients to accept a pacemaker implantation as a form of treatment. Therefore, more and more attention has been paid to cardiac vagus nerve ablation.

METHODS

In this study, 20 patients who met the inclusion criteria of GP ablation in the First Affiliated Hospital of Xinjiang Medical University from November 2019 to June 2020 were enrolled. Biochemical and other related examinations along with electrophysiological examinations were conducted before ablation, and then cardiac GP ablation was performed. The patients were followed up 3 times at 3, 6, and 12 months after the operation.

RESULTS

The minimum HR and mean HR were significantly increased after treatment with cardiac autonomic GP ablation (p<0.01). Moreover, the SDNN (Standard deviation of Normal-to-Normal Intervals) and RMSSD (Root mean square successive differences between successive R-R intervals) was significantly decreased after treatment with cardiac autonomic ganglion plexus ablation for 6 months and 12 months (p<0.01).

CONCLUSION

Cardiac GP ablation is relatively simple and easy to implement in units that have performed radiofrequency ablation for bradyarrhythmias. This procedure can be performed without any new equipment. Some patients with bradycardia may not have a permanent pacemaker implantation and may go in for additional treatment options.

Long-Term Evaluation of the Vagal Denervation by Cardioneuroablation Using Holter and Heart Rate Variability

Background:

Several disorders present reflex or persistent increase in vagal tone that may cause refractory symptoms even in a normal heart patient. Cardioneuroablation, the vagal denervation by radiofrequency ablation of the neuromyocardial interface, was developed to treat these conditions without pacemaker implantation. A theoretical limitation could be the reinnervation, that naturally grows in the first year, that could recover the vagal hyperactivity. This study aims to verify the vagal denervation degree in the chronic phase after cardioneuroablation. Additionally, it intends to investigate the arrhythmias behavior after cardioneuroablation.

Methods:

Prospective longitudinal study with intrapatient comparison of 83 very symptomatic cases without significant cardiopathy, submitted to cardioneuroablation, 49 (59%) male, 47.3±17 years old, having vagal paroxysmal atrial fibrillation 58 (70%) or neurocardiogenic syncope 25 (30%), New York Heart Association class<II and absence of significant comorbidities. Cardioneuroablation was performed in both atria by interatrial septum puncture, with irrigated conventional catheter and electroanatomic reconstruction. Ablation targeted the neuromiocardial interface by fragmentation mapping (AF-Nests) using the velocity fractionation software, conventional recording, and anatomic localization of the ganglionated plexi. Heart rate variability (time and frequency domain) and arrhythmias were compared by 24h-Holter, before, and 1 year and 2 years after cardioneuroablation. In a 40 month follow-up, 80% of patients were asymptomatic.

Results:

Time- and frequency-domain heart rate variability demonstrated significant decrease in all autonomic parameters, showing an important parasympathetic and sympathetic activity reduction at 2-year post-cardioneuroablation ( P <0.001). There was no difference in heart rate variability between the 1-year and 2-year post-cardioneuroablation ( P >0.05) suggesting that the reinnervation has halted. There was also an important reduction in all bradyarrhythmias and tachyarrhythmias pre-cardioneuroablation versus post-cardioneuroablation ( P <0.01).

Conclusions:

There is an important and significant vagal and sympathetic denervation after 2 years of cardioneuroablation with a significant reduction in bradyarrhythmia and tachyarrhythmia in the whole group. There were no complications.

Long-Term Follow-Up of Cardioneuroablation to Treat Second-Degree Block After Slow Pathway Ablation

We present the long-term follow-up of a 31-year-old woman who underwent cardioneuroablation (for atrioventricular (AV) block. Slow pathway ablation was performed in September 2017 with normal follow-up until April 2018, when the patient started noticing symptoms of palpitations at rest, and the electrocardiogram showed a Mobitz I AV block. A cardiac stress test and 24-h Holter monitoring demonstrated first- and second-degree block and normal AV conduction during times of higher heart rate. (Level of Difficulty: Advanced.)

Cardioneuroablation in the Management of Vasovagal Syncope, Sinus Node Dysfunction, and Functional Atrioventricular Block - Techniques

Cardioneuroablation is an emerging therapy to treat vasovagal syncope, functional atrioventricular block and sinus dysfunction. Currently, there are several effective approaches due to the complex modulation of autonomic nervous system. In this review, we describe techniques of this innovative therapy based on published literature and our experiences.

Role of Ganglionated Plexus Ablation in Atrial Fibrillation on the Basis of Supporting Evidence

The role of the autonomic nervous system (ANS) in the onset and maintenance of atrial fibrillation (AF) may be related to autonomic imbalance. The ANS may cause specific cellular electrophysiological phenomena, such as, shortening of the atrial effective refractory periods (ERPs) and ectopy based on firing activity in pulmonary vein myocytes. High frequency stimulation of atrial ganglionated plexi (GPs) may cause an increase in ERP dispersion and induce AF. Autonomic modification strategies by targeting GPs with catheter ablation have emerged as new targets. Various strategies have been used to detect location of GPs.However, it is still not clear which is the best method to localize GPs, how many GPs should be targeted, and what are the long-term consequences of these therapies. In this review, we discuss available evidence on the clinical impact of GP ablation to treat AF.

Relation of Fractionated Atrial Potentials With the Vagal Innervation Evaluated by Extracardiac Vagal Stimulation During Cardioneuroablation

BACKGROUND

Vagal hyperactivity is directly related to several clinical conditions as reflex/functional bradyarrhythmias and vagal atrial fibrillation (AF). Cardioneuroablation provides therapeutic vagal denervation through endocardial radiofrequency ablation for these cases. The main challenges are neuromyocardium interface identification and the denervation control and validation. The finding that the AF-Nest (AFN) ablation eliminates the atropine response and decreases RR variability suggests that they are related to the vagal innervation.

METHOD

Prospective, controlled, longitudinal, nonrandomized study enrolling 62 patients in 2 groups: AFN group (AFN group 32 patients) with functional or reflex bradyarrhythmias or vagal AF treated with AFN ablation and a control group (30 patients) with anomalous bundles, ventricular premature beats, atrial flutter, atrioventricular nodal reentry, and atrial tachycardia, treated with conventional ablation (non-AFN ablation). In AFN group, ablation delivered at AFN detected by fragmentation/fractionation of the endocardial electrograms and by 3-dimensional anatomic location of the ganglionated plexus. Vagal response was evaluated before, during, and postablation by 5 s noncontact vagal stimulation at the jugular foramen, through the internal jugular veins (extracardiac vagal stimulation [ECVS]), analyzing 15 s mean heart rate, longest RR, pauses, and atrioventricular block. All patients had current guidelines arrhythmia ablation indication.

RESULTS

Preablation ECVS induced sinus pauses, asystole, and transient atrioventricular block in both groups showing a strong vagal response (P=0.96). Postablation ECVS in the AFN group showed complete abolishment of the cardiac vagal response in all cases (pre/postablation ECVS=P<0.0001), demonstrating robust vagal denervation. However, in the control group, vagal response remained practically unchanged postablation (P=0.35), showing that non-AFN ablation promotes no significant denervation.

CONCLUSIONS

AFN ablation causes significant vagal denervation. Non-AFN ablation causes no significant vagal denervation. These results suggest that AFNs are intrinsically related to vagal innervation. ECVS was fundamental to stepwise vagal denervation validation during cardioneuroablation. Visual Overview A visual overview is available for this article.

Cardioneuroablation: Catheter Vagal Denervation as a New Therapy for Cardioinhibitory Syncope

The vasovagal syncope is the most frequent cause of transient loss of consciousness, especially in young people without significant heart disease. The malignant cardioinhibitory form is caused by abrupt and intense vagal reflex with or without defined triggers. Refractory cases to preventive measures and pharmacological handling has been treated with definitive pacemaker implantation. Besides showing questionable results, pacemaker implantation is highly rejected by young patients. In the late 1990s, we proposed specific vagal denervation by catheter ablation and spectral mapping, for paroxysmal AF, functional bradyarrhythmias and severe cases of malignant cardioinhibitory syncope giving rise to cardioneuroablation. Recently, many authors worldwide have been reproducing the cardioneuroablation results where elimination or significant reduction of the vagal response were observed, which abolished symptoms in more than 75% of patients followed up to 14 years, without complications. Therefore, cardioneuroablation has shown to be a real therapeutic option in malignant syncope cardioinhibitory and in any exclusive vagal mediated bradyarrhythmia without the need for pacemaker implantation.

Cardioneuroablação: A Denervação Vagal por Cateter Como Nova Terapia para Síncope Cardioinibitória

A síncope vasovagal é a causa mais frequente de perda transitória de consciência, especialmente em jovens sem doença cardíaca significativa. A forma cardioinibitória maligna é causada por reflexo vagal abrupto e intenso com ou sem gatilhos definidos. Casos refratários a medidas preventivas e manuseio farmacológico foram tratados com implante definitivo de marcapasso. Além de apresentar resultados questionáveis, o implante de marcapasso é altamente rejeitado por pacientes jovens. No final dos anos 1990, propusemos uma denervação vagal específica por ablação do cateter e mapeamento espectral para FA paroxística, bradiarritmias funcionais e casos graves de síncope cardioinibitória maligna dando origem à cardioneuroablação. Recentemente, muitos autores em todo o mundo vêm reproduzindo os resultados da cardioneuroablação, onde se observou eliminação ou redução significativa da resposta vagal, o que aboliu sintomas em mais de 75% dos pacientes acompanhados por até 14 anos, sem complicações. Portanto a cardioneuroablação tem se mostrado uma verdadeira opção terapêutica na síncope cardioinibitória maligna e em qualquer bradiarritmia vagal exclusiva mediada sem a necessidade de implante de marcapasso.

Right anterior ganglionated plexus: The primary target of cardioneuroablation?

BACKGROUND

Catheter ablation of ganglionated plexus (GP) as cardioneuroablation in the left atrium (LA) has been used to treat vasovagal syncope (VVS).

OBJECTIVE

The purpose of this study was to assess the effects of ablation of GPs on heart rate and to observe the acute, short-term, and long-term effects after cardioneuroablation.

METHODS

A total of 115 consecutive patients with VVS who underwent cardioneuroablation were enrolled. GPs of the LA were identified by high-frequency stimulation and/or anatomic landmarks being targeted by radiofrequency catheter ablation.

RESULTS

During ablation of right anterior ganglionated plexus (RAGP), heart rate increased from 61.3 ± 12.2 bpm to 82.4 ± 14.7 bpm (P <.001), whereas during ablation of other GPs only vagal responses were observed. During follow-up of 21.4 ± 13.1 months (median 18 months), 106 participants (92.2%) had no recurrence of syncope or presyncope. Holter data showed that minimal heart rate significantly increased at all follow-up time points (all P<.05), and mean heart rate remained higher than baseline 12 months after ablation (P = .001).

CONCLUSION

Cardioneuroablation via GP ablation in the LA effectively inhibited the recurrence of VVS. Ablation of RAGP could increase heart rate immediately and for the long term. This unique phenomenon may provide a new potential approach for treatment of neural reflex syncope or bradyarrhythmias.

Potential usage of cardioneuroablation in vagally mediated functional atrioventricular block

An increase in parasympathetic tone may be the main cause of some transient or permanent atrioventricular block cases. Some of these patients, defined as vagally mediated functional atrioventricular block, may be severely symptomatic and refractory to conventional therapies and may necessitate cardiac pacing. Cardioneuroablation is a relatively new strategy for management of patients with excessive vagal activation based on radiofrequency catheter ablation of main ganglionated plexi around the heart. Present review was dedicated to discuss potential usage of cardioneuroablation in patients with vagally mediated functional atrioventricular block.

Targets and End Points in Cardiac Autonomic Denervation Procedures

BACKGROUND

Autonomic denervation is an alternative approach for patients with symptomatic bradycardia. No consensus exists on the critical targets and end points of the procedure. The aim of this study was to identify immediate end points and critical atrial regions responsible for vagal denervation.

METHODS AND RESULTS

We enrolled 14 patients (50% men; age: 34.0±13.8 years) with cardioinhibitory syncope, advanced atrioventricular block or sinus arrest, and no structural heart disease. Anatomic mapping of ganglionated plexuses was performed, followed by radiofrequency ablation. Heart rate, sinus node recovery time, Wenckebach cycle length, and atrial-His (AH) interval were measured before and after every radiofrequency pulse. Wilcoxon signed-rank test was used for comparison. Significant shortening of the R-R interval (P=0.0009), Wenckebach cycle length (P=0.0009), and AH intervals (P=0.0014) was observed after ablation. The heart rate elevation was 23.8±12.5%, and the Wenckebach cycle length and AH interval shortening was 18.1±11% and 24.6±19%, respectively. Atropine bolus injection (0.04 mg/kg) did not increase heart rate further. Targeting a single spot of the left side (64% of the patients) or right side (36%) of the interatrial septum was observed to be responsible for ≥80% of the final R-R and AH interval shortening during ablation.

CONCLUSIONS

Targeting specific sites of the interatrial septum is followed by an increase in heart rate and atrioventricular nodal conduction properties and might be critical for vagal attenuation. The R-R interval, Wenckebach cycle length, and AH interval shortening, associated with a negative response to atropine, could be considered immediate end points of the procedure.

Differential effect of ganglionic plexi ablation in a patient with neurally mediated syncope and intermittent atrioventricular block

AIMS

In patients with severe neurally mediated syncope (NMS), radiofrequency catheter ablation (RFA) of ganglionic plexi (GP) has been proposed as a new therapeutic approach. Cardio-inhibitory response during NMS is usually related to the sinoatrial (SA) and less frequently to atrioventricular (AV) node. Differential effect of GP ablation on SA and AV node is poorly understood.

METHODS AND RESULTS

We report a case of a 35-year-old female with frequent symptomatic episodes of advanced AV block treated by anatomically guided RFA at empirical sites of GPs. After RFA at the septal portion of the right atrium-superior vena cava junction, heart rate accelerated from 62 to 91 beats/min and PR interval prolonged from 213 to 344 ms. Sustained first-degree AV block allowed to observe directly the effects of subsequent RFA on the AV nodal properties. Subsequent RFA at right- and left-sided aspects of the inter-atrial septum had no further effect on heart rate and PR interval. Ablation at the inferior left GP was critical for restoration of normal AV conduction (final PR interval of 187 ms). No bradycardia episodes were observed by implantable loop recorder during the follow-up of 10 months and the patient was symptomatically improved.

CONCLUSION

This is the first clinical case showing the differential effect of GP ablation on SA and AV nodal function, and critical importance of targeting the GP at the postero-inferior left atrium. The successful procedure corroborates clinical utility of ablation treatment instead of pacemaker implantation in selected patients with cardio-inhibitory NMS.