Conduction Block Research Articles

Efficacy and safety of a novel hexaspline pulsed field ablation system in patients with paroxysmal atrial fibrillation: the PLEASE-AF study.

Pulsed field ablation (PFA) is an emerging non-thermal ablative modality demonstrating considerable promise for catheter ablation of atrial fibrillation (AF). However, these PFA trials have almost universally included only Caucasian populations, with little data on its effect on other races/ethnicities. The PLEASE-AF trial sought to study the 12-month efficacy and the safety of a multi-electrode hexaspline PFA catheter in treating a predominantly Asian/Chinese population of patients with drug-refractory paroxysmal AF. Patients underwent pulmonary vein (PV) isolation (PVI) by delivering different pulse intensities at the PV ostium (1800 V) and atrium (2000 V). Acute success was defined as no PV potentials and entrance/exit conduction block of all PVs after a 20-min waiting period. Follow-up at 3, 6, and 12 months included 12-lead electrocardiogram and 24-h Holter examinations. The primary efficacy endpoint was 12-month freedom from any atrial arrhythmias lasting at least 30 s. The cohort included 143 patients from 12 hospitals treated by 28 operators: age 60.2 ± 10.0 years, 65.7% male, Asian/Chinese 100%, and left atrial diameter 36.6 ± 4.9 mm. All PVs (565/565, 100%) were successfully isolated. The total procedure, catheter dwell, total PFA application, and total fluoroscopy times were 123.5 ± 38.8 min, 63.0 ± 30.7 min, 169.7 ± 34.6 s, and 27.3 ± 10.1 min, respectively. The primary endpoint was observed in 124 of 143 patients (86.7%). One patient (0.7%) developed a small pericardial effusion 1-month post-procedure, not requiring intervention. The novel hexaspline PFA catheter demonstrated universal acute PVI with an excellent safety profile and promising 12-month freedom from recurrent atrial arrhythmias in an Asian/Chinese population with paroxysmal AF. ClinicalTrials.gov Identifier: NCT05114954.

Conductive block copolymer elastomers and psychophysical thresholding for accurate haptic effects.

Electrotactile stimulus is a form of sensory substitution in which an electrical signal is perceived as a mechanical sensation. The electrotactile effect could, in principle, recapitulate a range of tactile experience by selective activation of nerve endings. However, the method has been plagued by inconsistency, galvanic reactions, pain and desensitization, and unwanted stimulation of nontactile nerves. Here, we describe how a soft conductive block copolymer, a stretchable layout, and concentric electrodes, along with psychophysical thresholding, can circumvent these shortcomings. These purpose-designed materials, device layouts, and calibration techniques make it possible to generate accurate and reproducible sensations across a cohort of 10 human participants and to do so at ultralow currents (≥6 microamperes) without pain or desensitization. This material, form factor, and psychophysical approach could be useful for haptic devices and as a tool for activation of the peripheral nervous system.

Computational study of transcatheter aortic valve replacement based on patient-specific models-rapid surgical planning for self-expanding valves.

Transcatheter aortic valve replacement (TAVR) is a minimally invasive interventional solution for treating aortic stenosis. The complex post-TAVR complications are associated with the type of valve implanted and the position of the implantation. The study aimed to establish a rapid numerical research method for TAVR to assess the performance differences of self-expanding valves released at various positions. It also aimed to calculate the risks of postoperative paravalvular leak and atrioventricular conduction block, comparing these risks to clinical outcomes to verify the method's effectiveness and accuracy. Based on medical images, six cases were established, including the aortic wall, native valve and calcification; one with a bicuspid aortic valve and five with tricuspid aortic valves. The parameters for the stent materials used by the patients were customized. High strain in the contact area between the stent and the valve annulus may lead to atrioventricular conduction block. Postoperatively, the self-expanding valve maintained a circular cross-section, reducing the risk of paravalvular leak and demonstrating favorable hemodynamic characteristics, consistent with clinical observations. The outcomes of the six simulations showed no significant difference in valve frame morphology or paravalvular leak risk compared to clinical results, thereby validating the numerical simulation process proposed for quickly selecting valve models and optimal release positions, aiding in TAVR preoperative planning based on patients'geometric characteristics.

Wavefront curvature analysis derived from preprocedural imaging can identify the critical isthmus in patients with postinfarcted ventricular tachycardia

BackgroundWhere activation wavefront curvature is convexly shaped, functional conduction block can occur. ObjectiveThe purpose of this study was to determine whether left ventricular (LV) wall thickness determined from contrast-enhanced computed tomography (CT) is useful in localizing such areas in clinical postinfarction reentrant ventricular tachycardia (VT). MethodsWe evaluated data from 6 patients who underwent catheter ablation for postinfarction VT. CT imaging with inHEART processing was conducted 1–3 days before electrophysiological (EP) study to determine LV wall thickness (T). Activation wavefront curvature was approximated as ΔT/T, where ΔT represents wall thickness change. During EP study, bipolar LV VT electrograms were acquired using a high-density mapping catheter, and activation times were determined. Maps of T, ΔT/T, and VT activation were subsequently compared using statistical analyses. ResultsTwo of 6 cases exhibited dual circuit morphologies, resulting in a total of 8 VT morphologies analyzed. The LV wall near the VT isthmus location tended to be thin, on the order of a few hundred micrometers. Regions of largest ΔT/T partially coincided with the lateral isthmus boundaries where electrical conduction block occurred during VT. ΔT/T at the boundaries, measured from imaging, was significantly larger compared to values at the isthmus midline and to the global LV mean value (P <.001). ConclusionWavefront curvature measured by ΔT/T and caused by source–sink mismatch is dependent on ventricular wall thickness. Areas of high wavefront curvature partly coincide with and may be helpful in locating the VT isthmus in infarct border zones using preprocedural imaging analysis.

Efficacy of a surgical cardiac ablation clamp using nanosecond pulsed electric fields: An acute porcine model

ObjectiveTo examine the effectiveness of a recently developed nonthermal technology, nanosecond pulse-field ablation (nsPFA), for surgical ablation of the atria in a beating heart porcine model. MethodsSix pigs underwent sternotomy and ablation using an nsPFA parallel clamp. The ablation electrodes (53 mm long) were embedded in the jaws of the clamp. Nine lesions per pig were created in locations chosen to be representative of the Cox-maze procedure. Four lesions were intended to electrically isolate parts of the atrium: the right atrial appendage, left atrial appendage, right pulmonary veins, and left pulmonary veins. For these lesions, exit block testing was performed both after ablation and before euthanasia; the time between the 2 tests was 3.3 ± 0.5 hours (range, 2-4 hours). Using purse string sutures, 5 more lesions were created up to the superior vena cava, down to the inferior vena cava, across the right atrial free wall, and at 2 distinct locations on the left atrial free wall. The clamp delivered a train of nanosecond duration pulses, with a total duration of 2.5 seconds, independent of tissue thickness. The heart tissue was stained with 1% triphenyltetrazolium chloride after a dwelling period of 2 hours. Subsequently, each lesion was cross sectioned at 5-mm intervals to assess the ablation depth and transmurality. In some sections, transmurality could not be established on the basis of triphenyltetrazolium chloride staining alone; for these lesions, Gomori-trichrome stains were used, and the histologic sections were evaluated for transmurality. ResultsThe ablation time was 2.5 seconds per lesion, for a total of only 22.5 seconds ablation time to create 9 lesions. A total of 53 lesions were created, resulting in 388 separate histologic sections. Transmurality was established in 386 sections (99.5%). Mean tissue thickness was 3.1 ± 1.5 mm (range, 0.2-8.6 mm). Exit block was confirmed in 23 of the 24 lesions (96%) postablation and 23 of 24 (96%) before the animals were humanely killed. Over the course of the procedure, neither pulse-induced arrhythmias nor any other complications were noted. ConclusionsThe novel nsPFA clamp device was effective in creating acute conduction block and transmural lesions in both the right and left atria in an acute porcine model. This nonthermal energy source has great potential to both shorten procedural time and enable effective ablation in the beating heart.

Risk of Pacemaker Implantation After Aortic Root Replacement With and Without Valve Preservation

BackgroundWe compared the outcomes of aortic root replacement by composite valve grafts (CVG) and valve-sparing root replacement (VSRR) operations, with an emphasis on postoperative conduction block and the need for permanent pacemaker implantation (PPM). MethodsFrom 1997 to 2023, 1712 consecutive patients underwent ARR by VSRR (501 [29%]) or CVG (1211 [71%]) at a high-volume aortic center. ResultsPatients undergoing CVG were older (59 ± 14 vs 49 ± 14 years, P < .001), with more cardiovascular comorbidities. Compared with CVG, there were more women undergoing VSRR (17% vs. 13%, P = .042) and more patients with connective tissue disease (22% vs 7.3%, P < .001). Multivariable analysis found that the risk for PPM was higher after CVG compared with VSRR (6.5% vs 1.2%; odds ratio [OR], 2.83; 95% CI, 1.23-7.69; P = .024). Other variables associated with PPM include older age (OR, 1.03; 95% CI, 1.01-1.05; P = .006) preoperative renal impairment (OR, 2.69; 95% CI, 1.24-5.6; P = .010), previous operation (OR, 2.76; 95% CI, 1.29-5.62; P = .007), and bicuspid aortic valve (OR, 3.63; 95% CI, 2.13-6.33; P < .001). Among the CVG population, patients who are at increased risk are especially those with some degree of aortic stenosis (OR, 2.06; 95% CI, 1.18-3.61; P = .011). Patients who required PPM had no additive risk for long-term mortality (hazard ratio, 1.01; 95% CI, 0.47-2.17; P = .986); however, they were more likely to have reduced ejection fraction (29.3% vs 16%, P = .014). ConclusionsThe incidence of PPM after ARR is low, but rates were higher after CVG compared with VSRR.

The Combination of Hyperuricemia and Elevated High-Sensitivity C-Reactive Protein Increased the Risk of Cardiac Conduction Block.

This study aimed to explore the impact of a combination of hyperuricemia (HUA) and excessive high-sensitivity C-reactive protein (hs-CRP) levels on the likelihood of developing cardiac conduction block (CCB). Additionally, it sought to assess whether the influence of uric acid (UA) on CCB is mediated by hs-CRP. A prospective study was executed utilizing data from the Kailuan cohort, including 81,896 individuals initially free from CCB. The participants were categorized into four groups depending on the existence of HUA and low-grade inflammation (hs-CRP>3 mg/L). Cox regression analysis was employed to ascertain hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of incident CCB. A mediation analysis was performed to determine if hs-CRP functioned as a mediator in the connection between UA levels and the incidence of CCB. During a median observation period of 11.8 years, we identified 3160 cases of newly occurring CCB. Compared with the low UA/low CRP group, the combination of HUA and low-grade inflammation elevated the CCB risks (HR:1.56, 95% CI:1.22-1.99), atrioventricular block (AVB) (HR:1.88, 95% CI:1.27-2.77), and right bundle branch block (HR:1.47, 95% CI:1.02-2.12), respectively. Mediation analysis revealed that in the HUA group, compared with the non-HUA group, the risk of CCB elevated by 14.0%, with 10.3% of the increase mediated through hs-CRP. HUA combined with elevated hs-CRP increasedthe risk of CCB, especially AVB. The connection between UA and the CCB risk was partly mediated by hs-CRP.

Midterm follow-up results of implantation of a fully biodegradable ventricular septal defect occluder.

Ventricular septal defect (VSD) is a prevalent congenital cardiac anomaly. By enhancing the occluder design and optimizing procedural approaches, the indications for VSD closure can be broadened while minimizing associated complications. The utilization of fully biodegradable occluder holds promising potential in resolving conduction block issues encountered during VSD closure. This study aims to compare the results of the fully biodegradable occluder with the metal occluder in transoesophageal echocardiography-guided VSD closure via lower sternal level minor incision at the interim follow-up, and to find risk factors for the occurrence of electrocardiographic and valvular abnormalities postoperatively. We reviewed the postoperative and 3-year follow-up data of all patients who underwent the randomized controlled study of VSD closure from January 1 to November 7, 2019 in the Second Xiangya Hospital of Central South University. The safety and efficacy of the procedure were assessed and compared between the 2 groups by electrocardiogram and echocardiography results, and the risk factors for the occurrence of postoperative electrocardiogram and valve abnormalities were studied with Logistic regression analysis. Twelve and fifteen patients underwent VSD closure with the metallic occluder and the fully biodegradable occluder, respectively. All patients survived during the follow-up period without major complications such as atrioventricular block, significant residual shunt, too rapid absorption of the occluder, and significant valvular regurgitation. There were no significant differences in the results of electrocardiograph and color Doppler ultrasonography the metal occluder group and the fully biodegradable occluder group 1, 2, and 3 years after operation (all P>0.05). The size of the occluder were risk factors for tricuspid regurgitation at 2 and 3 years postoperatively, and the difference between the occluder size and the VSD defect size were risk factors for tricuspid regurgitation at 2 years postoperatively (P<0.05). This study adequately demonstrates the safety and efficacy of fully biodegradable occluders in small VSD closure and shows the same postoperative effects as conventional nitinol occluders.

Source-sink mismatch and conduction block: simulation study

Abstract Background Source-sink mismatch is one of the key concepts in arrhythmia mechanism such as relationship between pulmonary veins and the left atrium in atrial fibrillation. We sought to find the condition for conduction block in various geometries. Methods To simulate cardiac atrial tissue, the finite element method was used to discretize the governing equation in a 2D mesh. We evaluated under the following conditions: 6 sizes of source width (0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mm), 64 types of angle (θ) at the junction (30-330 degrees), 3 conditions of conduction velocity (CV) (x0.5, x0.75, and x1 of normal CV of atrial myocardium). Results Conduction block was not observed with source width &amp;gt; 0.5 mm in any settings. In reduced CV condition, conduction block was not observed in θ &amp;lt; 300 degrees when source width &amp;gt; 0.3 mm. The higher CV, conduction block was observed in the narrower θ. In cases of CV of x1.0 and x0.75, conduction block was observed in θ &amp;lt; 180 degrees when source width &amp;lt; 0.3 mm. The smaller source width, conduction block was observed in the narrower θ. The wider θ, the easier conduction block occurred. Conclusion Conditions for conduction block due to source-sink mismatch are as follows: smaller source width, higher CV, and wider θ. Source with width &amp;gt; 0.5 mm may not be associated with source-sink mismatch in the atrial tissue. CV slowing by antiarrhythmic drugs can be effective in the aspect of source-sink mismatch.

Manifestation of conduction block zones by substrate mapping evaluated under multidirectional pacing during ventricular tachycardia ablation

Abstract Introduction Catheter ablation (CA) has proven to be effective therapy for ventricular tachycardia (VT) in patients with structural heart disease. However, activation mapping during VT is often limited in case of non-inducible, non-sustained or hemodynamically tolerable. It has been reported that a substrate-based approach for identifying conduction block and slow-conducting sites during sinus rhythm and ventricular pacing is promising strategies for CA. However, detailed analysis on the effectiveness of substrate mapping with multidirectional pacing to identify critical isthmus in unmappable VT have been lacking. Purpose The purpose of the present study was to evaluate the effectiveness of substrate mapping with multidirectional pacing in VT ablation. Methods From April 2022 to July 2023, 7 consecutive patients (4 men, age 62±9years) who underwent CA of VTs at our institute were enrolled. Isochronal late activation mapping (ILAM) was performed during sinus rhythm, right ventricular (RV) and left ventricular (LV) pacing. Cardiovascular magnetic resonance were performed in 3 of 7 cases to assess the distribution of myocardial late gadolinium enhancement. For catheter ablation, 2Fr electrode catheter was inserted into the anterior interventricular vein (AIV) at the distal site of the coronary sinus. LV pacing was performed using an electrode catheter placed in the AIV. ILAM were constructed by annotating the last deflection of each electrogram. Results In the 7 patients, 5 had ischemic cardiomyopathy and 2 had non-ischemic cardiomyopathy (Figure 1). During sinus rhythm, a deceleration zone (DZ) was identified in only 1 of 7 cases, consistent with linear conduction block. RV pacing demonstrated DZ in 3 of 7 cases. LV pacing revealed DZ in 6 of 7 cases, all of which had conduction blocks. U-shaped conduction blocks, which was not detectable in activation mapping during sinus rhythm, was newly identified in 29% of RV pacing, 71% of LV pacing. Combined RV and LV pacing unmasked the U-shaped conduction block in 86% of the cases. Only in case 7, activation mapping of VT with a cycle length of 470ms could be performed, and VT isthmus activation was observed in the area surrounded by the U-shaped conduction block (Figure 2). In other cases, the clinical VTs were unmappable because of the hemodynamic instability with tachycardia cycle length of approximately 300 milliseconds. Eventually, VTs became non-inducible in 3 of 5 cases in which induction was performed after the CA. During the follow-up period of 7±5 months, 6 of 7 cases remained free from any VT episodes. One patient showed small amount of pericardial effusion after CA. However, there were no life-threatening complications in any patients. Conclusion Substrate mapping using several different wavefront vectors in unstable VTs unveiled conduction block zones that might be potential ablation target sites for VT.Figure 1Figure 2

Effect of atrial extrasystoles in electrophysiological properties in heart failure patients

Abstract Background Patients with heart failure (HF) most likely have an extensive arrhythmogenic substrate which increases vulnerability to atrial fibrillation (AF). Conduction disorders underlying this increased AF vulnerability -hidden during sinus rhythm- may be unmasked by spontaneous atrial extrasystole (AES). Objective The aim of this study is to investigate the impact of AES on potential arrhythmogenic electrophysiological properties in patients with HF and AES. Methods Intraoperative epicardial mapping of the right and left atrium (RA, LA), Bachmann’s bundle (BB) and pulmonary vein area (PVA) was performed in 132 patients (10 with HF and 122 without HF). Differences in unipolar potential morphologies and conduction disorders during SR and spontaneous AES were determined. Results A median of 1 (1–3) AES per patient were included. In patients with HF, AES were associated with lower median potential voltages (1.94mV versus 4.02mV, P&amp;lt;0.001), more low voltage areas (10.98% versus 4.97%, P=0.004) and a higher number of short double potentials (28.5% versus 13.0% of short double potentials, P&amp;lt;0.001) compared to patients without HF. Comparing differences (AES - SR) in parameters between patients with and without HF, there was a larger increase in long double potentials (+5.32% versus +0.31%, P&amp;lt;0.001), fractionated potential (+4.18% versus +0.49%, P=0.001), conduction block (+3.39% versus +0.63%, P=0.002) and continuous conduction delay and block (+6.72% versus +1.74%, P=0.001) in HF patients. Conclusions In HF patients, AES cause lower unipolar potentials voltages and more conduction disorders than in patients without HF. Differences in arrhythmogenic properties between sinus rhythm and atrial extrasystoles are more pronounced in HF patients. These results suggest that HF patients have hidden arrhythmogenic substrates that can be uncovered by AES and may explain the increased AF vulnerability.

A proposed index of myocardial staining for vein of marshall ethanol infusion

Abstract Background Mitral isthmus(MI) conduction block is a fundamental step in anatomical approach treatment for persistent atrial fibrillation(PeAF). However, MI block is hardly achievable with endocardial ablation only. Retrograde ethanol infusion(EI) into the vein of Marshall(VOM) facilitates MI block. Fluorographic myocardial staining(MS) during VOM-EI could be helpful in predicting procedural alcoholization outcome even if its role is qualitatively assessed in the routine. Purpose The aim was to quantitatively assess MS during VOM-EI and to evaluate its association with MI block achievement. Methods Consecutive patients undergoing catheter ablation for PeAF at our Institution from February 2022 to May 2023 were considered. Patients with identifiable VOM were included. A proposed index of MS(MSI) was retrospectively calculated in each included patient. Correlation of MSI with low voltage zones(LVZ) extension after VOM-EI and its association with MI block achievement were assessed. Results 42 patients out of 49 (85.8%) had an identifiable VOM. MI block was successfully achieved in 35 patients out of 42 (83.3%). MSI was significantly associated with the occurrence of MI block (OR 1.24 (1.03 – 1.48); p = 0.022). A higher MSI resulted in reduced ablation time (p = 0.014) and reduced radiofrequency applications (p = 0.002) to obtain MI block. MSI was also associated with MI block obtained by endocardial ablation only (OR 1.07 (1.02 – 1.13); p = 0.002). MSI was highly correlated with newly formed LVZ extension (r = 0.776; p = 0.001). Conclusion In our study cohort, optimal MSI predicts MI block and facilitates its achievement with endocardial ablation only.Myocardial stainingSpline plots

Validating peak frequency mapping for atrial far-field electrogram detection: insights from a pulmonary vein isolation model

Abstract Introduction Effective pulmonary vein isolation (PVI) is the cornerstone of AF ablation, and conduction block from the atrium to the pulmonary veins (PV) is the accepted method to demonstrate it. However, far-field electrograms may make challenging to establish whether PVI has been achieved. Purpose This study aimed to evaluate whether peak frequency (PF) mapping can effectively identify far-field electrograms in the superior PVs following a redo PVI procedure. Methods Left atrium and PV activation and voltage bipolar 3D electroanatomical maps were generated using a steerable catheter with a 16-grid-patterned electrode configuration (HD-Grid) during coronary sinus pacing, both before and after the redo PVI. PF maps were developed offline using specialized experimental software. Only reconnected superior PVs from the redo PVI procedure were included in the analysis. Results Twenty consecutive patients (mean age 63±12 years, 12 male) were prospectively enrolled in the study, with 15 presenting reconnected PVs after the redo PVI. Conduction gaps were identified in the superior PVs of 9 patients (7 in the left superior PV, 5 in the right superior PV). Following the redo PVI, both voltage (0.96±1.1 mV vs. 0.49±1.21, P&amp;lt;0.01) and PF (285±134 vs. 153±112 Hz, P&amp;lt;0.001) were significantly reduced in both superior PVs. This reduction was more prominent in the right superior PV (0.83±0.75 vs. 0.20±0.39 mV, 299±159 vs. 132±116 Hz) than in the left superior PV (1.08±1.32 vs. 0.83±1.67 mV, 272±105 vs. 178±101 Hz). High-voltage (&amp;gt;0.3 mV) electrograms remained prevalent in the right (12%) and left (37%) superior PVs after the redo PVI. However, high PF (&amp;gt;250 Hz) electrograms significantly decreased following PVI in both the right (64% before vs. 6% after PVI) and left (66% before vs. 22% after PVI) PVs. Only a small percentage (5.3% in the right PV and 12% in the left PV) of all electrograms exhibited both high voltage and high PF following the PVI (see figure). Conclusion PF mapping proves to be a valuable tool in distinguishing far-field electrograms from atrial activity in the PVs, offering additional insights to complement voltage mapping, particularly in the context of redo PVI procedures.

Systematic right ventricular electrophysiologic evaluation in patients with repaired tetralogy of Fallot before pulmonary valve replacement

Abstract Introduction Adults with repaired tetralogy of Fallot (rToF) are prone to develop ventricular tachycardia (VT) in adulthood, due to reentry related to slowly conducting anatomical isthmuses (SCAI). Pulmonary valve replacement (PVR) in patients without history of VT, may lead to obliteration of unrecognized SCAI with subsequent catheter ablation failure; electrophysiologic study is thus recommended before PVR. A systematic evaluation of the topology of SCAI in this population is, however, scant. Methods Consecutive rToF patients undergoing PVR with native right ventricular outflow tract were studied with pre-PVR EPS. Electroanatomical mapping with systematic evaluation of all possible anatomical isthmuses (AI) with pacemapping, activation mapping in sinus/paced rhythm and bipolar voltage mapping was performed (AI1: anterior scar/patch to tricuspid annulus; AI2: anterior scar to pulmonary annulus; AI3: pulmonary annulus to ventricular septal defect – VSD- patch; AI4: VSD to tricuspid annulus). Conduction velocity (CV) across all documented AI was calculated (ratio between the distance among the nearest point with bipolar voltage &amp;gt;1.5 mV and their difference in activation timing). Ventricular programmed stimulation was performed at 2 sites (apex and outflow tract) with drive train ad 600/400 ms, up to three extrastimuli until refractoriness or induction, during baseline and isoproterenol infusion. Radiofrequency catheter ablation (RFCA) was performed in all patients with inducible VT and/or SCAI, aiming at conduction block across the SCAI validated with differential pacing. Results Between May 2023 and November 2023, 10 patients with rToF and 1 double outlet right ventricle were studied (73% males, age 46±10 years; 54% with a previous shunt, 46% with a previous transannular patch, 27% pulmonary valvotomy and infundibular boring; median age at surgery 4 years, interquartile range 3-6). EPS was positive for inducible VT in 4 patients (mean cycle length 297 ms, 3 with left bundle branch morphology and 1 right bundle branch morphology, all inferior axis) and polymorphic VT in 1. AI1 was present in 5 patients, AI2 in 5, AI3 in 7, AI 4 in 2. At least 1 SCAI was present in 7 patients (64%), 2 SCAI in 3 patients (43% of patients with SCAI; in every patient SCAI3+SCAI2 in 2 and SCAI 4 in 1 patient). There were no SCAI1; there were 3 SCAI 2 (mean CV 0.43 m/s), 4 SCAI 3 (mean CV 0.3 m/s), 1 SCAI 4 (CV 0.4 m/s). RFCA was performed in 8 patients; acute success was achieved in all patients, achieving bidirectional conduction block across treated SCAI and non-inducibility of VT. Conclusions SCAI are often present in rToF candidate to PVR and without clinical history of spontaneous VT, involving prevalently SCAI3 and SCAI2. Inducible VT is not sufficient as a marker of arrhythmic risk and SCAI should be better sought for. RFCA of SCAI with bidirectional conduction block is acutely highly efficacious.

Ablation of hemodynamically unstable ventricular tachycardia guided by ultra-high density pacemapping and PASO correlation map, a multi-center clinical trial

Abstract Background Due to hemodynamic instability during ventricular tachycardia (VT), obtaining a complete electroanatomic map is often difficult if not impossible. Pace-mapping has progressed but still lacks precision and may not reveal sufficient details for complete ablation of the potential critical isthmus. Purpose We hypothesized that a novel strategy of combining ultra-high density (HD) pace-mapping using the PASO algorithm and Carto system to match the induced/clinical VT may aid in the reconstruction of the VT critical isthmus and effective VT ablation leading to reduce the risks of VT recurrence. Methods This was a prospective, multi-center trial conducted between January 2021 and July 2023. We enrolled 30 patients with ischemic heart disease and scar mediated recurrent VT clinically indicated for ablation. Following induction of clinical VT, we performed ultra-HD pace-mapping (5-10 mm distance between pacing points) of the identified ventricular substrate. Using PASO Module, a pacing correlation map (PCM) was constructed based on the percentage match to the induced VT. Using the PCM and the measured stimulation to electrogram intervals, the potential VT critical isthmus was reconstructed. Radiofrequency ablation was carried out to completely transect the delineated isthmus. Post ablation, repeat HD mapping and ablation was performed, until the PASO % correlation dropped from &amp;gt;93% to &amp;lt;70%, indicating at least uni-directional (orthodromic to the perceived VT circuit) conduction block through the ablation line. Follow-up data, including ICD interrogations were collected via chart review. Outcomes were compared to 60 propensity-score matched patients with an ICD who were enrolled in the Ranolazine in High-Risk Patients with Implanted Cardioverter-Defibrillators (RAID) trial who did not undergo VT ablation and served as the control group. The primary endpoint was the first occurrence of any VT at 1-year of follow-up. Results Patients enrolled had a mean age of 69 ± 9 years and 13% were women. Propensity matched patients from the RAID trial had similar baseline clinical characteristics to patients who underwent VT ablation (Table). At 1 year follow up, there was a significantly lower cumulative probability of VT/VF recurrent events in the patients who underwent PCM guided ablation as compared with the control group (17% vs 69%, respectively; log-rank p&amp;lt;0.001 Figure). There were no serious procedure related complications with all patients remaining free of adverse events or death at 30 days. Conclusion Our findings suggest that ablation for unstable or unmappable VT is enhanced by ultra-high density pace-mapping to reconstruct the potential VT circuit and is associated with a significantly lower rate of recurrent VT as compared with patients managed with aggressive and escalating medical therapy.Cumulative probability of ICD therapyBaseline clinical characteristics

P.062 Normal NCS in 42-year-old man with PMP22 duplication

Background: Charcot Marie Tooth disease is a polygenic disorder with cannonical features of distal amyotrophy, acrohypesthesia, and tight tendoachilles of either axonal (type 2) or demeylinating (type 1) varieties. Type 1 CMT patients are required to possess conduction slowing of a sufficient degree to qualify as demyelinating. Presented is a middle-aged man with an unremarkable neurologic exam and normal electrophysiology. Methods: Standard electrophysiological techniques were employed to obtain the nerve conduction data (Natus Nicolet EDX AT2; Middleton, WI, USA). Repeated next generation sequencing and deletion/duplication analyses were performed. Results: The nerve conduction studies showed no evidence of demyelination in the upper or lower extremeties. The duplication error was confirmed with repeat testing. The heterozygous PMP22 gene duplication encompassed the entire coding sequence involving exons 1-5. Conclusions: CMT1A accounts for the vast majority of dysmyelinating hereditary neuropathies. Phenotypic variability is well described. Presentations include (a) classic conduction slowing, (b) intermediate slowing, (c) conduction block, (d) HNPP-like, (e) absent CMAPs, and (f) normal NCSs in young infants. This is the first case of a neurologically intact adult with CMT1A. Cryptogenic genetic modifier-effect(s) are posited as a possible explanation of the lack of penetrance. Identifying the nature of this modification may prove instructive for future therapies.

Temporal evolution of His bundle pacing thresholds: a sub-study of the PACE-CONDUCT trial

Abstract Background His bundle pacing (HBP) has become a valuable alternative for cardiac resynchronization therapy, offering physiological pacing. This substudy of the PACE-CONDUCT trial aimed to explore the influence selective and non-selective HBP on threshold height. We assessed these parameters in patients with both normal conduction and bundle branch block conduction. Methods Our study included 61 consecutive patients with a median age of 73 years, who underwent a successful HBP implantation for indications such as sick sinus syndrome, AV Block 2 type 2, binodal disease, and ablate and pace therapy prior to AV-node ablation. Among these patients, 18 exhibited QRS durations exceeding 150 ms, indicating a complete and broad bundle branch block which made them candidates for cardiac resynchronization therapy (CRT). All patients received HBP implantation with the assistance of a 3D electroanatomical system. This system allowed for low-fluoroscopic, atraumatic evaluation of the His bundle (HB) area, presenting the His voltage as a color-coded map for precise electrode placement. Results The feasibility of bundle branch correction is generally accepted in selective HBP distal to the site of block, albeit associated with higher threshold values and potentially lower battery duration. Our analysis encompassed 61 patients who underwent HBP implantation, with 23 patients (37,7%) exhibiting selective HBP and 38 (62,3%) non-selective HBP. Remarkably, 10 out of the 23 patients with selective HBP demonstrated a complete bundle branch block correction after HBP implantation even with a basal QRS durations exceeding 150 ms. We evaluated HBP thresholds at implantation, one day post-implantation, and one month post-implantation, correlating these data with selective and non-selective HBP. Threshold values were converted to volts per millisecond (volts × milliseconds) for analysis. Statistical analysis conducted with IBM SPSS 29.0 revealed a significant difference at the day of implantation, indicating higher threshold capture in selective HBP compared to non-selective HBP (one-sided p-value: &amp;lt; 0.01, two sided p value 0.01). However, this difference could not be sustained at the one-day and one-month threshold follow-ups, suggesting normalization of the selective HBP threshold. Conclusion In our study, the initially higher threshold in selective HBP normalized within 24 hours compared to non-selective HBP. Additionally, our study demonstrated the feasibility of selective His pacing in patients with complete bundle branch block and broad QRS durations. These findings provide insights into HBP optimization and encourage further investigations with larger patient cohorts to validate our observations and enhance patient care in the realm of cardiac pacing.Threshold trend

Trans-catheter cryoablation of parahisian accessory pathways: a single centre experience

Abstract Introduction Transcatheter radiofrequency (RF) ablation of perinodal accessory pathways (parahisian/midseptal APs) is still challenging especially in young patients due to a high risk for inadvertent atrioventricular block (AVB) requiring permanent pacing. Recently, cryo-ablation (CA) has evolved as an RF alternative, thanks to a safer profile and a better catheter stability. Purpose To evaluate the safety, efficacy and outcomes of CA in patients with parahisian/midseptal APs. Methods 73 pts undergoing a first ablation of septal APs at our institution were retrospectively analyzed. Among these, we selected 20 patients with a diagnosis of para-hisian/midseptal AP confirmed by EP study (EPS) and 3D-electro-anatomic mapping (EAM), ablated using cryoenergy. Before delivering CA, a cryomapping (CM) at the target AP site was performed at −30°C using a 6- mm-tip catheter. Successful CM was defined as: (1) loss of delta wave in case of manifest pre-excitation, (2) termination of a sustained AVRT, (3) retrograde conduction block through the AP during ventricular pacing in case of concealed AP. CA was initiated following successful CM, at a temperature of −75°C for 300 s with an additional "bonus" CA application (300s). Acute procedural endpoint was permanent complete abolition of AP conduction; long-term clinical endpoint was defined as no recurrence of delta wave or AVRT on serial ECG monitoring at follow-up (1, 6, 12 months). RESULTS Baseline characteristics are summarized in Fig. 1. Fifty-five % were pediatric patients, only 3/20 presented a structural HD. Up to 90% of the patients experienced a symptomatic AVRT, while delta-wave was present at baseline ECG in 19/20 patients. EPS combined with 3D-EAM showed a para-hisian AP in 80% and a mid-septal AP in 20%. Mean distance between His bundle electrogram and AP site was 5.72 mm (4-6.8 mm, Fig. 2). Orthodromic AVRT was induced in all the 20 pts. Maen procedural and fluoroscopy times were, respectively, 103.4 ± 26.4 and 3.15± 1.76 min . Acute success was achieved in 20/20 patients (100%) with AP block of conduction obtained within few seconds (&amp;lt;10s) after a mean CM number of 3.3 ± 1.2 (Fig. 2). Two patients developed transient 2:1 AV block and 1 patient transient RBBB during CM, with immediate recovery within 20s from CM termination. No peri-procedural complications or permanent AV block were observed. One patient had an early AP re-conduction (6 hours later) and was successfully re-ablated the following day. During a mean FU of 361 ± 34 days, only two patients (10%) experienced an AVRT recurrence and underwent a second successful CA. Conclusions Cryoablation of parahisian and midseptal APs is a safe and effective alternative to RF, resulting in a low risk of recurrence over 12-months-follow-up with no incidence of permanent AV block. A near-zero fluoroscopy approach combining CA and 3D-EAM is feasible and should be considered especially in very young patients with parahisian APs.Fig. 1Fig. 2

Feasibility and safety of cavotricuspid isthmus ablation using exclusive intracardiac echocardiography guidance: a proof-of-concept, observational trial

Abstract Introduction Catheter ablation is the preferred treatment for typical atrial flutter (AFl), although it can pose challenges due to anatomical abnormalities. The integration of 3D electroanatomical mapping systems (EAMS) has notably diminished the need for fluoroscopy in AFl ablation procedures. Intracardiac echocardiography (ICE) has also demonstrated advantages in reducing radiation exposure during AFl ablation. Nevertheless, there is a lack of evidence on the feasibility of ICE-guided, zero-fluoroscopy AFl ablation without the use of EAMS. Methods In this prospective study, we enrolled 80 patients with CTI-dependent AFl. The initial 40 patients underwent ablation guided by standard fluoroscopy along with ICE (Standard ICE group), whereas the remaining 40 patients underwent zero-fluoroscopy ablation exclusively using ICE (Zero ICE group). Procedure outcomes, including acute success, procedural duration, fluoroscopy duration, radiation dose, and any associated complications, were compared between the groups. Results Both groups achieved a 100% acute success rate. In the Zero ICE group, the zero-fluoroscopy approach was successfully executed in 39 out of 40 cases (97.5%). There were no significant differences in procedure time (55.5 (46.5; 66.8) min vs. 51.5 (44.0; 65.5), p=0.50) and puncture to first ablation time (18 (13.5; 23) min vs. 19 (15; 23.5) min, p=0.50) between the groups. The Zero ICE group had significantly lower fluoroscopy time (57 (36.3; 90) sec vs. 0 (0; 0) sec, p&amp;lt;0.001) and dose (3.17 (2.27; 5.63) mGy vs. 0 (0; 0) mGy, p&amp;lt;0.001 compared to the Standard ICE group. Total ablation time was longer in the Standard ICE group (597 (447; 908) sec vs. 430 (260; 750), p=0.02), but total ablation energy (22458 (14836; 31116) Ws vs. 17043 (10533; 29302) Ws, p=0.10) did not differ significantly. First-pass bidirectional conduction block of the CTI and acute reconnection rates were comparable between the groups. No complications or recurrences were noted during the follow-up period. Conclusion ICE-guided, zero-fluoroscopy CTI ablation for AFl using only ICE is feasible and safe. This method effectively eliminates radiation exposure without compromising procedural duration, total ablation time, or acute success rates.isthmus ablation by ICE

Feasibility and safety of left atrial roof ablation with the third-generation visually guided laser balloon

Abstract Background The roof area ablation beyond pulmonary vein (PV) isolation (PVI) using a cryoballoon has been widely performed for patients with atrial fibrillation (AF). However, the feasibility of roof area ablation using a visually guided laser balloon (VGLB) remains to be elucidated. Purpose This study aims to investigate the feasibility and safety of additional roofline creation by VGLB ablation alone in patients with AF. Methods A total of 30 patients with AF (paroxysmal AF=15, persistent AF=15) who underwent VGLB ablation from March 2023 to August 2023 were analyzed retrospectively. VGLB ablation was performed using a third-generation VGLB. After initial circular ablation, VGLB was inflated to a larger size to extend and fuse the isolation area at the roof portion during the superior PVs occlusion. The complete conduction block of the left atrial (LA) roof was assessed by the differential pacing methods and the high-resolution mapping system at the end of the procedure. Results Acute success in complete roofline creation was achieved in 70% of patients. The PVI time was 21.6±5.5 minutes, and additional roof ablation time was 8.7±3.5 minutes, respectively. The anatomical LA roof length was significantly shorter in patients with successful roofline generation than without (30.4±7.2mm vs. 42.9±4.0mm, P&amp;lt;0.001). A cut-off value of 40.2mm for the LA roof length calculated by a receiver operating characteristic curve predicted a successful construction of the LA roofline with the highest sensitivity of 94.7%, specificity of 83.3%, and the area under the curve was 0.94 (95% confidence interval, 0.35-0.99). No complications occurred during laser energy titration at the roof area. Conclusion The roofline creation using a third-generation VGLB is possible with acceptable safety concerns. The length of the LA roof≤40.2mm was a predictor of the successful LA roofline generation.Fluoroscopic and endoscopic imageVoltage map after ablation