Quantitative assessment of transient autonomic modulation after single-shot pulmonary vein isolation with pulsed-field ablation.

INTRODUCTION: Pulmonary vein isolation (PVI) with thermal energy is characterized by concomitant ablation of the surrounding ganglionated plexi (GP). Pulsed-field ablation (PFA) selectively targets the myocardium and seems associated with only negligible effects on the autonomic nervous system (ANS). However, little is known about the dynamic effects of PFA on the GP immediately after PVI. This study sought to investigate the degree and acute vagal modulation induced by the FarapulseTM PFA system during PVI compared with single-shot thermal ablation. METHODS: A total of 76 patients underwent first-time PVI with either FarapulseTM PFA (PFA group, n = 40) or cryoballoon ablation (thermal ablation group, n = 36) for paroxysmal atrial fibrillation (AF). The effect on the ANS in the two groups was assessed before and after PVI with extracardiac vagal stimulation (ECVS). To capture any transient effects of PFA on the ANS, in a subgroup of PFA patients ECVS was repeated at three predefined timepoints: (1) before PVI (T0); (2) immediately after PVI (T1); and (3) 10 min after the last energy application (T2). RESULTS: Despite similar baseline values, the vagal response induced by ECVS after PVI almost disappeared in the thermal ablation group but persisted in the PFA group (thermal group: 840 [706-1090] ms, p < .001 compared to baseline; PFA group: 11 466 [8720-12 293] ms, p = .70 compared to baseline). Intraprocedural vagal reactions (defined as RR increase >50%, transitory asystole, or atrioventricular block) occurred more frequently with PFA than thermal ablation (70% vs. 28%, p = .001). Moreover, heart rate 24 h post-PVI increased more with thermal ablation than with PFA (16.5 ± 9.0 vs. 2.6 ± 6.1 beats/min, p < .001). In the subgroup of PFA patients undergoing repeated ANS modulation assessment (n = 11), ECVS demonstrated that PFA determined a significant acute suppression of the vagal response immediately after PVI (p < .001 compared to baseline), which recovered almost completely within 10 min. CONCLUSION: PVI with the FarapulseTM PFA system is associated with only transitory and short-lasting vagal effects on the ANS which recover almost completely within a few minutes after ablation. The impact of this phenomenon on AF outcome needs to be further investigated.

Renal nerve stimulation identifies aorticorenal innervation and prevents inadvertent ablation of vagal nerves during renal denervation.

PURPOSE: Recently we reported the use of renal nerve stimulation (RNS) during renal denervation (RDN) procedures. RNS induced changes in blood pressure (BP) and heart rate are not fully delineated yet. We hypothesized that electrical stimulation of the sympathetic nerve tissue in the renal artery would lead to an increase in BP and vagal stimulation would cause a decrease in BP. We report the different patterns of BP and heart rate responses elicited by RNS prior to RDN. METHODS: 35 patients with drug-resistant hypertension were included. RNS was performed under general anesthesia at four sites in the right and left renal arteries, both before and immediately after RDN. RNS-induced BP and heart rate changes were monitored. RESULTS: A total of 289 RNS sites in 35 patients were analyzed. An increase in systolic BP of >10 mmHg was regarded as a positive BP response to RNS. This pattern of response was observed in 180 sites (62%). 86 RNS sites (30%) showed an indifferent response with BP changes ≤10 mmHg. At 13 sites (4.5%) RNS elicited a decrease in BP up to -8 mmHg. However, 10 RNS sites (3.5%) showed a pronounced vagal response with hypotension and sinus cycle lengths ranging between 4224-10272 milliseconds. These sites were distributed among two patients. CONCLUSION: RNS identified sympathetic and parasympathetic nerve tissue in the renal arteries. RNS can be potentially used to map nerve bundles and guide selective ablation of sympathetic nerve fibers and prevent inadvertent ablation of parasympathetic nerve tissue during RDN.

Pulsed field ablation of the right superior pulmonary vein prevents vagal responses via anterior right ganglionated plexus modulation.

BACKGROUND: Pulsed field ablation (PFA) is selective for the myocardium. However, vagal responses and reversible effects on ganglionated plexi (GP) are observed during pulmonary vein isolation (PVI). Anterior-right GP ablation has been proven to effectively prevent vagal responses during radiofrequency-based PVI. OBJECTIVE: The purpose of this study was to test the hypothesis that PFA-induced transient anterior-right GP modulation when targeting the right superior pulmonary vein (RSPV) before any other pulmonary veins (PVs) may effectively prevent intraprocedural vagal responses. METHODS: Eighty consecutive paroxysmal atrial fibrillation patients undergoing PVI with PFA were prospectively included. In the first 40 patients, PVI was performed first targeting the left superior pulmonary vein (LSPV-first group). In the last 40 patients, RSPV was targeted first, followed by left PVs and right inferior PV (RSPV-first group). Heart rate (HR) and extracardiac vagal stimulation (ECVS) were evaluated at baseline, during PVI, and postablation to assess GP modulation. RESULTS: Vagal responses occurred in 31 patients (78%) in the LSPV-first group and 5 (13%) in the RSPV-first group (P <.001). Temporary pacing was needed in 14 patients (35%) in the LSPV-first group and 3 (8%) in the RSPV-first group (P = .003). RSPV isolation was associated with similar acute HR increase in the 2 groups (13 ± 11 bpm vs 15 ± 12 bpm; P = .3). No significant residual changes in HR or ECVS response were documented in both groups at the end of the procedure compared to baseline (all P >.05). CONCLUSION: PVI with PFA frequently induced vagal responses when initiated from the LSPV. Nevertheless, an RSPV-first approach promoted transient HR increase and reduced vagal response occurrence.

Autonomic Responses During Acute Anterior Versus Inferior Myocardial Infarction: A Systematic Review and Meta-Analysis.

Autonomic responses elicited by myocardial infarction vary depending on the site of injury, but accurate assessment using heart rate variability during the acute phase is limited. We systematically searched PubMed without language restrictions throughout July 2023. We reviewed studies reporting autonomic indices separately for anterior and inferior infarcts, followed by a meta-analysis of those reporting the standard deviation of the inter-beat interval between normal sinus beats during the initial 24 hours after the onset of symptoms. Six studies were included, comprising 341 patients (165 anterior, 176 inferior infarcts), all with satisfactory scores on the Newcastle-Ottawa quality scale. The estimated average of the standardized mean difference (based on the random-effects model) was -0.722 (95% confidence intervals: -0.943 to -0.501), which differed from zero (z=-6.416, p<0.0001). This finding indicates sympathetic and vagal dominance during acute anterior and inferior infarcts, respectively, with excessive responses likely contributing to early arrhythmogenesis. Despite the amelioration of autonomic dysfunction by revascularization, infarct location should be considered when commencing ß-adrenergic receptor blockade, especially after delayed procedures.

Ultrasound-guided extracardiac vagal stimulation-New approach for visualization of the vagus nerve during cardioneuroablation.

BACKGROUND: Fluoroscopy-guided extracardiac vagal stimulation (ECVS) from the internal right and left jugular veins (RIJV and LIJV) is routinely used to document vagal response (sinus arrest and/or atrioventricular block) during cardioneuroablation. Ultrasound-guided ECVS allows direct visualization and selective stimulation of the vagus nerve (VN). OBJECTIVES: The objectives of this study were to assess the feasibility of ultrasound-guided ECVS and to compare it with fluoroscopy-guided ECVS. METHODS: The study group consisted of 48 patients (25 men [52%]; mean age 38 ± 15 years) in whom fluoroscopy-guided ECVS and ultrasound-guided ECVS were performed. For fluoroscopy-guided ECVS, a pacing electrode was introduced into the RIJV and into the LIJV up to the level of the jugular foramen under fluoroscopic guidance. For ultrasound-guided ECVS, the VN and electrode were visualized using ultrasonography. Partial vagal response was defined as induction of sinus arrest or atrioventricular block, whereas full vagal response was defined as induction of both. RESULTS: ECVS was performed in all patients from the RIJV and in 45 from the LIJV. Visualization of the VN using ultrasound was possible in 44 patients (92%). During ECVS from the RIJV, partial vagal response was obtained in 39 (81%) using fluoroscopy-guided ECVS vs 45 (94%) using ultrasound-guided ECVS (not significant) whereas full vagal response was obtained in 27 patients (56%) using fluoroscopy-guided ECVS vs 40 (83%) using ultrasound-guided ECVS (P = .0071). For ECVS from the LIJV, partial vagal response was achieved in 40 (89%) vs 44 (98%) patients (not significant) whereas full vagal response was achieved in 30 (67%) vs 40 (89%) patients (P = .021) (fluoroscopy-guided ECVS vs ultrasound-guided ECVS, respectively). CONCLUSION: Ultrasound-guided ECVS is feasible and full vagal response is achieved significantly more frequently than using fluoroscopy-guided ECVS.

Does a Vagal Response Indicate Cardiac Autonomic Modulation and Improve the Therapeutic Effect of Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation? Insights from Cryoballoon Ablation.

Background: The incidence and influence of vagal response (VR) observed during cryoballoon-based pulmonary vein isolation (CBA-based PVI) on the cardiac autonomic nervous system (CANS) and ablation outcomes in paroxysmal atrial fibrillation (PAF) remain unknown. Methods: 296 patients were treated with a 28 mm second-generation cryoballoon (Medtronic). A total of 74 patients without structural heart disease and concomitant diseases were chosen for a detailed CANS assessment with a heart rate variability (HRV) analysis. All patients were screened over a 2-year post-ablation period. Results: VR was detected in 30% of patients and included sinus arrest (64%) or severe sinus bradycardia (46%). The presence of VR was not related to PV ostial dimension, patient clinical characteristics or intraprocedural ablation details. CANS modulation, manifesting as increased median HR and decreased HRV parameters with intact sympatho-vagal balance occurred independently of VR presence or absence and sustained for at least 12 months following ablation. VR was not related with more intensive CANS modulation and did not translate into better ablation outcomes when compared to the non-VR group (74% vs. 71% at 12 months and 69% vs. 65% at 24 months respectively). Conclusions: VR is frequent during CBA-based PVI for PAF and unrelated to any additional clinical benefit.

Recurrent Episodes of Paroxysmal Supraventricular Tachycardia Triggered by Dyspepsia: A Rare Case of Gastrocardiac Syndrome.

Supraventricular tachycardia (SVT) refers to the narrow complex tachycardia originating at or above the bundle of His. Several risk factors are associated with the development and recurrence of SVT, but its association with gastric problems, especially dyspepsia, is relatively rare. We report the case of a 54-year-old female who presented to the emergency room (ER) with palpitations, which were diagnosed as an episode of paroxysmal supraventricular tachycardia (PSVT). She had a history of PSVT in the past, along with hypertension and dyspepsia. After thorough history and examination, dyspepsia was identified as the common trigger of her PSVT episodes, pointing towards the likelihood of gastrocardiac symptoms. Therefore, an appropriate regimen of beta-blockers, proton pump inhibitors (PPIs), and anti-foaming agents (simethicone) was prescribed to manage her symptoms with the plan to perform a catheter ablation later.

Asystole During Nasopharyngeal Swab: Is COVID-19 to Blame?

The use of nasopharyngeal (NP) swab sampling for the detection of various respiratory pathogens has been a standard procedure in medicine for many years. While this is a fairly common procedure, there has been a significant increase in utilization recently due to the SARS-CoV-2 pandemic. We describe a case of a 40-year-old SARS-CoV-2 positive patient with no prior cardiac history who developed asystole while an NP swab was being used to obtain a sample for a SARS-CoV-2 assay. Return of normal sinus rhythm was achieved with chest compressions alone. The incident was deemed to have been an exaggerated vagal response to intranasal stimulation; better known as the trigeminocardiac reflex. This is the first reported case describing asystole during use of an NP swab. This case occurred in a patient with no known cardiac disease and highlights the potential importance of the arrhythmogenic nature of COVID-19 that could potentiate the vagal response in susceptible individuals undergoing NP sampling.

The impacts of the ganglionated plexus ablation sequence on the vagal response, heart rate, and blood pressure during cardioneuroablation.

AIMS: Cardioneuroablation is an emerging and promising therapy to treat vasovagal syncope (VVS). The aim of this study was to assess the characteristics of vagal response (VR), heart rate (HR), and blood pressure (BP) during cardioneuroablation with different sequences of ganglionated plexus (GPs) catheter ablation and clarify the regulatory mechanism of cardiac GPs of the left atrium. METHODS: A total of 28 patients with VVS who underwent cardioneuroablation were prospectively enrolled and randomly assigned to 2 groups according to the ablation order of GPs. Group A: Left superior GP (LSGP) - Left inferior GP (LIGP) - Right inferior GP (RIGP) - Right anterior GP (RAGP); Group B: RAGP - LSGP - LIGP - RIGP. RESULTS: In Group A, the VR in LSGP, LIGP, RIGP, and RAGP during ablation was observed in 11 (78.6%), 5 (35.7%), 4 (28.6%) and 2 (14.3%) cases, respectively. In contrast, in Group B, the VR in RAGP, LSGP, LIGP, and RIGP was observed in 2 (14.3%), 1 (7.1%), 0 (0%) and 0 (0%) cases, respectively. BP reduction during procedure was observed eight times in Group A and once in Group B (P = 0.013). In both groups, the HR increased significantly during ablation of the RAGP (all P < 0.001). CONCLUSION: The sequence of GPs ablation during cardioneuroablation affected the occurrence rate of VR and BP reduction during cardioneuroablation. The RAGP was a critical target to increase HR and inhibit VR and BP reduction during procedure, indicating that it may be a key GP in regulation of the cardiac vagal activity.

Cough syncope whilst driving - An unusual yet serious presentation.

Cough is a common symptom of cardiorespiratory pathology, yet its vasomotor effects are underappreciated. We report a case of a 45-year-old male who had a Cough Syncopal event resulting in a road traffic collision. Although he was unhurt and fully recovered, we believe there is need for greater understanding of this unusual sequence of events.

Sympathetic and Vagal Responses Elicited by Acute Stress in Rats.

Introduction Acute emotional stress triggers autonomic responses that affect sympathovagal balance. However, the temporal pattern of changes in each autonomic arm during stress and recovery remains unclear. Therefore, we analyzed separately sympathetic and vagal activity, elicited by acute unpredictable stress in a rat model. Methods Continuous electrocardiographic recording was performed during (32 minutes) and after (two hours) successive use of restraint and air-jet stress in 10 rats, whereas five rats served as controls. Sympathetic and vagal indices were calculated non-invasively after heart rate variability analysis. Voluntary motion was quantified during recovery, as an index of continuing anxiety. Results The sympathetic nervous system index increased during stress and remained elevated during the initial stage of recovery. The parasympathetic nervous system index decreased immediately after the onset of stress and remained low throughout the observational period. During recovery, voluntary activity was more pronounced in the stress group than in the controls. Conclusion Successive restraint and air-jet stress in rats increased sympathetic activity and decreased vagal activity. These changes displayed only partial recovery post-stress and were accompanied by enhanced voluntary motion. Our findings may be important in the evaluation of the cardiac electrophysiologic implications of autonomic changes elicited by acute emotional stress.

A case of prolonged sinus arrest for 5 minutes after Cryo-balloon ablation to the left superior pulmonary vein.

A 63-year-old man was referred to our hospital for his palpitation due to atrial fibrillation. He was admitted for catheter ablation. Cryoablation was applied to the left superior pulmonary vein for 180 seconds, and its potential disappeared in 22 seconds. The lowest temperature was -45°C. Suddenly, sinus arrest was observed 1 minute after the completion of freezing. The right ventricle was paced but no atrial potential was observed for 5 minutes until normal sinus rhythm resumed. We report a case of severe sinus arrest after cryoablation to the left pulmonary vein.

Endothelin receptors in the brain modulate autonomic responses and arrhythmogenesis during acute myocardial infarction in rats.

AIMS: Endothelin has been implicated in various processes in the brain, including the modulation of sympathetic responses. The present study examined the pathophysiologic role of brain endothelin-receptors in the setting of acute myocardial infarction, characterized by high incidence of ventricular tachyarrhythmias. MAIN METHODS: We investigated the effects of intracerebroventricular administration of antagonists of endothelin-receptors ETA, ETB, or both, during a 24 h-observation period post-coronary ligation in (n = 70) rats. Continuous recording was performed via implanted telemetry transmitters, followed by arrhythmia-analysis and calculation of autonomic indices derived from heart rate variability. The regional myocardial electrophysiologic properties were assessed by monophasic action potentials and multi-electrode recordings. KEY FINDINGS: Sympathetic-activity was decreased and vagal-activity was enhanced after intracerebroventricular ETA-receptor blockade, thus attenuating regional myocardial repolarization inhomogeneity. As a result, the incidence of ventricular tachyarrhythmias was markedly lower in this group. Such effects were also observed after intracerebroventricular blockade of ETB-, or both, ETA- and ETB-receptors, although to a lesser extent. SIGNIFICANCE: ETA-receptors in the brain modulate sympathetic and vagal responses and alter arrhythmogenesis during evolving myocardial necrosis in rats. These findings provide insights into arrhythmogenic mechanisms during acute myocardial infarction and call for further investigation on the role of endothelin in the central autonomic network.

Heart Rate Variability Responses of Individuals With and Without Saline-Induced Obstructive Sleep Apnea.

STUDY OBJECTIVES: Postoperative development of obstructive sleep apnea (OSA) has been attributed to the fluid overloaded state of patients during the postoperative period. In this context, alterations in cardiac autonomic regulation caused by OSA may explain the increased postoperative risk for adverse cardiovascular events. This study tests the hypothesis that individuals with fluid overload-induced OSA will experience autonomic dysregulation, compared to those without fluid overload-induced OSA. METHODS: Twenty-one normotensive, nonobese (mean body mass index 24.5 kg/m2) males (mean age 37 years) underwent a sleep study. Participants were randomly assigned to infusion with saline during sleep either at the minimum rate (control) or as a bolus of 22 mL/kg body weight (intervention). Participants were blinded to the intervention and crossed over to the other study arm after 1 week. Measures of heart rate variability were calculated from electrocardiography recordings presaline and postsaline infusion in the intervention arm. Heart rate variability measures computed were: standard deviation of the RR interval; root mean square of successive differences; low-frequency, high-frequency, and total power; and the ratio of low-frequency to high-frequency power. RESULTS: Although presaline infusion values were similar, postsaline infusion values of the standard deviation of the RR interval and high-frequency power were lower in the group whose apnea-hypopnea index increased in response to saline infusion, compared to the group whose apnea-hypopnea index did not increase in response to saline infusion (P < .05 for both). CONCLUSIONS: Fluid overload-induced OSA is accompanied by a reduction in heart rate variability, consistent with vagal withdrawal. Future work should explore autonomic dysregulation in the postoperative period and its association with adverse events.

Vagal response in cryoballoon ablation of atrial fibrillation and autonomic nervous system: Utility of epicardial adipose tissue location.

BACKGROUND: Mechanism and effects of vagal response (VR) during cryoballoon ablation procedure on the cardiac autonomic nervous system (ANS) are unclear. The present study aimed to evaluate the relationship between VR during cryoballoon catheter ablation for atrial fibrillation and ANS modulation by evaluating epicardial adipose tissue (EAT) locations and heart rate variability (HRV) analysis. METHODS: Forty-one patients with paroxysmal atrial fibrillation (11 with VR during the procedure and 30 without VR) who underwent second-generation cryoballoon ablation were included. EAT locations and changes in HRV parameters were compared between the VR and non-VR groups, using Holter monitoring before ablation, immediately after ablation and one month after ablation. RESULTS: The total EAT volume surrounding the left atrium (LA) in the VR and non-VR groups was 29.0±18.4 cm3 vs 27.7±19.7 cm3, respectively (p=0.847). The VR group exhibited greater EAT volume overlaying the LA-left superior pulmonary vein (PV) junction (6.1±3.6 cm3 vs 3.6±3.3 cm3, p=0.039) than the non-VR group. HRV parameters similarly changed following ablation in both the groups. EAT volume overlaying LA-right superior PV junction was significantly correlated with the relative changes in root-mean-square successive differences (r=-0.317, p=0.043) and high frequency (r=-0.331, p=0.034), immediately after the ablation. CONCLUSIONS: Changes in HRV parameters following ablation were similarly observed in both the groups. EAT volume on the LA-PV junction is helpful for interpretation of VR occurrence and ANS modulation.

Vagal response during pulmonary vein isolation: Re-recognized its characteristics and implications in lone paroxysmal atrial fibrillation.

BACKGROUND: The role of autonomic innervation around the pulmonary vein (PV) antrum in the genesis of atrial fibrillation (AF) has been demonstrated but the characteristics of radiofrequency induced vagal response (VR) in the PV antrum and its clinical impact on pulmonary vein isolation (PVI) for paroxysmal AF need to be further elucidated. METHOD: Of 995 consecutive patients with symptomatic paroxysmal AF undergoing PVI at a single center over a 2-year period, 516 met exclusion criteria and the remaining 479 patients, 156 positive VR (PVR) and 323 negative VR (NVR), underwent 12-month follow-up. The primary endpoint was freedom from AF or other sustained atrial tachycardia (AT), verified by monthly visits and electrocardiographic monitoring. The frequency-domain analysis was performed to evaluate the autonomic activity before and after the procedure. RESULTS: VR was most commonly elicited during PVI at the LSPV roof (65.4%) and anterior RSPV (44.9%, with a >5s sinus pause in 37/70 [52.8%] cases). Compared with the NVR group, ablation was associated with reduced AF recurrence at 12 months in the PVR (hazard ratio: 0.53, 95% confidence interval: 0.22-0.89). Furthermore, the PVR group showed a significantly abbreviated AF cycle length at the left PV, and significantly lower HF and LF parameters with stable LF/HF ratio during follow-up. CONCLUSION: Complete elimination of vagal response, most commonly elicited by radiofrequency application around the roof of LSPV and anterior RSPV, appeared associated with reduced 12-month recurrence of AF and with marked heart rate variability changes consistent with autonomic nervous withdrawal.