Ablation Of Right Ventricular Outflow Tract Research Articles

PO-05-067 THE USE OF THE HIS BUNDLE LOCAL ACTIVATION TIME IN OUTFLOW TRACT PREMATURE VENTRICULAR CONTRACTIONS TO ASSIST IN LOCALIZATION

Localization of premature ventricular contractions (PVCs) from the outflow tract regions based upon ECG localization criteria may prove challenging based upon cardiac rotation and surface lead placement. Multiple studies describe ECG parameters based upon axis and precordial R wave transition for distinction of left (LVOT) vs right ventricular outflow tract (RVOT) site of origin. No previous studies describe intracardiac fiducial points to assist in site discrimination for PVC origin between LVOT, RVOT, and intramyocardial sites. Assessment of PVC timing at the His bundle region (HB) as a predictor for area of origin of a premature ventricular contraction. Timing at the area of the HB could help discriminate LVOT, RVOT, and intramural PVCs and guide ablation strategy. We performed retrospective analysis of 30 consecutive patients who underwent a PVC ablation from July 2021 until present day. During index mapping, placement of a multipolar catheter in the HB yielded local activation timing (LAT) for PVCs, and the HB was marked on the mapping system . The timing of a PVC was recorded as well as the area of successful ablation. Of the 30 patients 10 were female and 20 male with an average age of 60 years. The average EF was 52%. 10 patients had coronary artery disease 9 had ICDs. 10 Patients with successful LVOT ablation had HB LAT average of -6 msec +/- 12msec. 8 Patients with successful RVOT ablation had HB LAT average of 32 msec +/-11msec. 12 patients with successful intramyocardial ablation had HB LAT of 45 msec +- 8 msec. The difference between LVOT HB LAT and RVOT HB LAT was statically significant P<0.001. The difference between LVOT HB LAT and intramyocardial HB LAT was statistically significant P<0.001. The difference between RVOT HB LAT and intramyocardial HB LAT was statistically significant P<0.0062. Use of the HB as an intracardiac fiducial point for LAT assists with accurate localization and successful ablation of PVCs originating from the outflow tracts.

Post-ablation augmentation of skin sympathetic nerve activity predicts a poor outcome of idiopathic ventricular arrhythmias

BackgroundThe neuromodulation effect after ventricular arrhythmia (VA) ablation is unclear. The study aimed to investigate skin sympathetic nerve activity (SKNA) changes in patients receiving catheter ablations for idiopathic VA. MethodsOf 43 patients with drug-refractory symptomatic VA receiving ablation, SKNA was continuously recorded for 10 min during resting from electrocardiogram lead I configuration and bipolar electrodes on the right arm 1 day before and 1 day after ablation. ResultsTwenty-two patients with acute procedure success and no recurrence during follow-ups were classified as sustained success group (group 1). Other 21 patients were classified as failed ablation group (group 2). Baseline SKNA showed no significant difference between the two groups. Post-ablation SKNA in group 2 was significantly higher than in group 1. In patients with ablation involved right ventricular outflow tract (RVOT), the post-ablation SKNA was also significantly higher in group 2. In contrast, there was no difference in post-ablation SKNA between groups in patients receiving non-RVOT ablation. ConclusionThe neuromodulation response after RVOT ablation may correspond to the sympathetic nerve distribution at RVOT. Augmentation of sympathetic activity after VA ablation indicates an unsuccessful VA suppression, especially in patients receiving ablation of RVOT VA.

Contact- versus noncontact-guided ablation of the right ventricular outflow tract arrhythmias: A propensity score matched analysis.

There are unique advantages and disadvantages in the choice of contact mapping (CM) versus noncontact mapping (NCM) systems during ablation of right ventricular outflow tract (RVOT) arrhythmias. This study compared acute procedural success and clinical outcomes in matched patients undergoing CM- versus NCM-guided RVOT ablation. A total of 167 consecutive patients with idiopathic RVOT ventricular arrhythmias underwent NCM- or CM-guided ablation. Propensity scoring was used to match each patient undergoing NCM-guided ablation to one control patient undergoing CM-guided ablation. A total of 120 patients were included in this final analysis. If initial ablation was acutely unsuccessful in either group, patients crossed over to the other group. Ablation was acutely successful in 47 of 60 (78.3 %) patients in the NCM group and 55 of 60 (91.7%) in the CM group (P=.002). Thirteen NCM patients required CM and two CM patients crossed over to utilize NCM (P=.002). Procedural duration, fluoroscopy time, and dose in NCM were greater than that in CM (P<.05, respectively). However, procedural complications were not different between two groups. During a mean follow-up of 51 ± 20.6 months, 51 of the 60 NCM patients remained free of arrhythmia, while 48 of the 60 CM patients had no recurrent arrhythmias (P=.47). Contact mapping, compared to NCM, is the superior initial technique to guide RVOT arrhythmia ablation due to a higher procedural success without the need to switch to alternative mapping techniques and shorter procedural and fluoroscopic times.

Impact of catheter-tissue contact force on lesion size during right ventricular outflow tract ablation in a swine model.

BackgroundThe catheter-tissue contact force (CF) is one of the significant determinants of lesion size and thus has a considerable impact on the effectiveness of ablation procedures. This study aimed to evaluate the impact of CF on the lesion size during right ventricular outflow tract (RVOT) ablation in a swine model.MethodsTwelve Guangxi Bama miniature male pigs weighing 40 to 50 kg were studied. After general anesthesia, a ThermoCool SmartTouch contact-sensing ablation catheter was introduced to the RVOT via the femoral vein under the guidance of the CARTO 3 system. The local ventricular voltage amplitude and impedance were measured using different CF levels. We randomly divided the animals into the following four groups according to the different CF levels: group A (3–9 g); group B (10–19 g); group C (20–29 g); and group D (30–39 g). Radiofrequency ablations were performed at three points in the free wall and septum of the RVOT in power control mode at 30 W for 30 s while maintaining the saline irrigation rate at 17 mL/min. At the end of the procedures, the maximum depth, surface diameter, and lesion volume were measured and recorded. A linear regression analysis was performed to determine the relationship between continuous variables.ResultsA total of 72 ablation lesions were created in the RVOT of the 12 Bama pigs. The maximum depth, surface diameter, and volume of the lesions measured were well correlated with the CF (free wall: β = 0.105, β = 0.162, β = 3.355, respectively, P < 0.001; septum: β = 0.093, β = 0.150, β = 3.712, respectively, P < 0.001). The regional ventricular bipolar voltage amplitude, unipolar voltage amplitude, and impedance were weakly positively associated with the CF (β = 0.065, β = 0.125, and β = 1.054, respectively, P < 0.001). There was a significant difference in the incidence of steam pops among groups A, B, C, and D (free wall: F = 7.3, P = 0.032; septum: F = 10.5, P = 0.009); and steam pops occurred only when the CF exceeded 20 g. Trans-mural lesions were observed when the CF exceeded 10 g in the free wall, while the lesions in the septum were non-trans-mural even though the CF reached 30 g.ConclusionsCF seems to be a leading predictive factor for the size of formed lesions in RVOT ablation. Maintaining the CF value between 3 and 10 g may be reasonable and effective for creating the necessary lesion size and reducing the risk of complications, such as steam pops and perforations.

Clinical and electrophysiological characteristics of ventricular arrhythmias arising from pulmonary cusps.

IntroductionVentricular arrhythmias (VAs) have been successfully ablated from the pulmonary sinus cusps establishing pulmonary artery (PA) as a distinct site of arrhythmic foci. The aim of the present study was to determine the clinical presentation, electrocardiographic, and ablation characteristics of PA‐VAs.MethodsThirty consecutive patients with right ventricular outflow tract (RVOT)‐type VAs were included in this retrospective study. Three‐dimensional electroanatomic mapping was performed in all patients. Mapping was performed initially in RVOT, and later within the PA. Mapping was performed in the PA if there was no early activation, unsatisfactory pace‐map, or ablation in RVOT were unsuccessful. All PA‐VAs were mapped and ablated by looping the catheter in a reverse U fashion.ResultsAmong 30 patients, 8 (26.6%) patients VAs were successfully ablated within PA. Electrocardiography (ECG) revealed that the QRS duration was significantly wider in the PA‐VAs group compared to the RVOT‐VAs group (155 ± 14.14 vs 142.40 ± 8.12 ms, P < .01). Mapping by reversed U method of PA‐VAs revealed earlier activation (55 ± 9.66 vs 12.00 ± 8.61 ms, P < .01) in PA compared to RVOT. An isolated discrete prepotential was present at the successful site in 50% (n = 4).ConclusionPulmonary artery‐VAs are an important subset of VA originating from the outflow tract. They have a wider baseline QRS duration compared to RVOT‐VAs. Presence of a prepotential aids in the identification of a successful ablation site. Mapping utilizing the reversed U method can help in localization and successful ablation of PA‐VAs.

Feasibility of zero or near zero fluoroscopy during catheter ablation procedures.

Awareness of risks associated with radiation exposure to patients and medical staff has significantly increased. It has been reported before that the use of advanced three-dimensional electroanatomical mapping (EAM) system significantly reduces fluoroscopy time, however this study aimed for zero or near zero fluoroscopy ablation to assess its feasibility and safety in ablation of atrial fibrillation (AF) and other tachyarrhythmias in a "real world" experience of a single tertiary care center. This was a single-center study where ablation procedures were attempted without fluoroscopy in 34 consecutive patients with different tachyarrhythmias under the support of EAM system. When transseptal puncture (TSP) was needed, it was attempted under the guidance of intracardiac echocardiography (ICE). Among 34 patients consecutively enrolled in this study, 28 (82.4%) patients were referred for radiofrequency ablation (RFA) of AF, 3 (8.8%) patients for ablation of right ventricular outflow tract (RVOT) ventricular extrasystole (VES), 1 (2.9%) patient for ablation of atrioventricular nodal reentry tachycardia (AVNRT), 2 (5.9%) patients for typical atrial flutter ablation. In 21 (62%) patients the en- tire procedure was carried out without the use of fluoroscopy. Among 28 AF patients, 15 (54%) patients underwent ablation without the use of fluoroscopy and among these 15 patients, 10 (67%) patients required TSP under ICE guidance while 5 (33%) patients the catheters were introduced to left atrium through a patent foramen ovale. In 13 AF patients, fluoroscopy was only required for double TSP. The total procedure time of AF ablation was 130 ± 50 min. All patients referred for atrial flutter, AVNRT, and VES of the RVOT ablation did not require any fluoroscopy. This study demonstrates the feasibility of zero or near zero fluoroscopy procedure including TSP with the support of EAM and ICE guidance in a "real world" experience of a single tertiary care center. When fluoroscopy was required, it was limited to TSP hence keeping the radiation dose very low.

Hybrid thoracoscopic epicardial ablation of right ventricular outflow tract in patients with Brugada syndrome

Abnormal delayed electrograms (EGMs) from the anterior wall of the right ventricular outflow tract (RVOT) epicardium have become the ablation target in Brugada syndrome (BrS). The aim of this study was to analyze the safety, feasibility, and efficacy of a novel hybrid thoracoscopic approach to perform epicardial RVOT radiofrequency ablation in BrS. Thirty-six patients with BrS (26 men (72.2%); mean age 36.6±15.8 years; range 3-63 years) who underwent hybrid thoracoscopic epicardial ablation of RVOT from January 2016 to April 2018 were included in this study. Two expert electrophysiologists analyzed the EGMs during ajmaline challenge and guided the surgeon to perform ablation. Ajmaline challenge was repeated after 1 month to assess the absence of the BrS electrocardiographic pattern. Patients were followed by remote monitoring and outpatient visits every 6 months. The elimination of all abnormal EGMs was achieved in 94.4% of patients. After a mean follow-up of 16 ± 8 months (range 6-30 months), freedom from ventricular arrhythmias was obtained in 7 (77.8%) patients in secondary prevention 9/36 (25%) and in 24 (100%) patients in primary prevention 24/36 (75%). Major complications were observed in 1 patient (2.8%), who experienced late cardiac tamponade. Hybrid thoracoscopic epicardial RVOT ablation in BrS is a safe and feasible approach, allowing direct visualization of ablation during radiofrequency delivery. Because of ventricular arrhythmia recurrences, implantable cardioverter-defibrillator implantation is still mandatory in patients treated in secondary prevention and with high risk.

Microstructural substrate in RVOT for Brugada syndrome

Brugada syndrome is linked to ventricular fibrillation (VF), a precursor to sudden cardiac death. This patient population suffers from electrical abnormalities originating from the right ventricular outflow tract (RVOT). The mechanisms underlying such arrhythmic activity remain unclear, but clinical electrophysiological observations have indicated conduction abnormalities in the RVOT. To mimic sub-clinical epicardial microstructural defects in the RVOT to provide a substrate for conduction delay as a possible mechanism of BrS. Dual coronary-perfused left and right ventricular wedge preparations were studied in 20 pigs (35–45 kg). Patchy microlesions were created through an array of ablation needles in either the RVOT, right ventricle (RV) or both (DOUBLE ablation) and compared to a control group in the absence of ablation. Paced and arrhythmic activity were assessed by optical mapping of the epicardial surface in the presence and absence of the sodium channel blocker, flecainide. At baseline, the action potential duration (APD80) is shorter in the RVOT region compared to the RV free wall (209.8 ms ± 26.91 vs. 212.6 ± 37.19, P = 0.026). APD80 of the RVOT is prolonged by ablation (228.1 ms ± 23.02 for RVOT ablation and 231.2 ms ± 27.18 for double ablation vs 202.5 ms ± 45.37 for RV ablation and 209.8 ms ± 26.91 for control, P < 0.0001). Arrhythmia complexity was greatest in the RVOT ablation group compared to control (dominant frequency 8.016 Hz ± 1.286 vs. 5.834 Hz ± 1.726, P = 0.0191). Rotors were preferentially clustered to the ablation area in the RVOT ablation group compared to control. Microstructural defects in the RVOT provides the substrate for sustained ventricular arrhythmias.

Two Different Left Bundle Branch Block Patterns of Premature Ventricular Contraction Originating from Right Coronary Cusp

A 52 year-old woman presented at the emergency center in our hospital for syncope. She had previously been diagnosed with right ventricular outflow tract (RVOT) ventricular tachycardia at a private clinic 15 years previously. Her electrocardiogram indicated frequent premature ventricular contractions (PVCs), with all the observed PVCs exhibiting left bundle branch block patterns and inferior axis. Majority of PVCs had a positive QRS complex in lead I, but a small number of PVCs exhibited a negative QRS complex in lead I. How- ever, RVOT ablation failed to eliminate the PVCs. Instead, the PVCs were mitigated with radiofrequency catheter ablation at the right coronary cusp.

Fibrosis, Connexin-43, and Conduction Abnormalities in the Brugada Syndrome

BackgroundThe right ventricular outflow tract (RVOT) is acknowledged to be responsible for arrhythmogenesis in Brugada syndrome (BrS), but the pathophysiology remains controversial. ObjectivesThis study assessed the substrate underlying BrS at post-mortem and in vivo, and the role for open thoracotomy ablation. MethodsSix whole hearts from male post-mortem cases of unexplained sudden death (mean age 23.2 years) with negative specialist cardiac autopsy and familial BrS were used and matched to 6 homograft control hearts by sex and age (within 3 years) by random risk set sampling. Cardiac autopsy sections from cases and control hearts were stained with picrosirius red for collagen. The RVOT was evaluated in detail, including immunofluorescent stain for connexin-43 (Cx43). Collagen and Cx43 were quantified digitally and compared. An in vivo study was undertaken on 6 consecutive BrS patients (mean age 39.8 years, all men) during epicardial RVOT ablation for arrhythmia via thoracotomy. Abnormal late and fractionated potentials indicative of slowed conduction were identified, and biopsies were taken before ablation. ResultsCollagen was increased in BrS autopsy cases compared with control hearts (odds ratio [OR]: 1.42; p = 0.026). Fibrosis was greatest in the RVOT (OR: 1.98; p = 0.003) and the epicardium (OR: 2.00; p = 0.001). The Cx43 signal was reduced in BrS RVOT (OR: 0.59; p = 0.001). Autopsy and in vivo RVOT samples identified epicardial and interstitial fibrosis. This was collocated with abnormal potentials in vivo that, when ablated, abolished the type 1 Brugada electrocardiogram without ventricular arrhythmia over 24.6 ± 9.7 months. ConclusionsBrS is associated with epicardial surface and interstitial fibrosis and reduced gap junction expression in the RVOT. This collocates to abnormal potentials, and their ablation abolishes the BrS phenotype and life-threatening arrhythmias. BrS is also associated with increased collagen throughout the heart. Abnormal myocardial structure and conduction are therefore responsible for BrS.

GW24-e2281 Magnetic versus manual catheter navigation for mapping and ablation of right ventricular outflow tract ventricular arrhythmias: a randomised controlled study

ObjectivesThere has been no randomised controlled study to prospectively compare the performance and clinical outcomes of remote magnetic control (RMC) versus manual catheter control (MCC) during ablation of right ventricular...

Magnetic versus manual catheter navigation for mapping and ablation of right ventricular outflow tract ventricular arrhythmias: A randomized controlled study

No randomized controlled study has prospectively compared the performance and clinical outcomes of remote magnetic control (RMC) vs manual catheter control (MCC) during ablation of right ventricular outflow tract (RVOT) ventricular premature complexes (VPC) or ventricular tachycardia (VT). The purpose of this study was to prospectively evaluate the efficacy and safety of using either RMC vs MCC for mapping and ablation of RVOT VPC/VT. Thirty consecutive patients with idiopathic RVOT VPC/VT were referred for catheter ablation and randomized into either the RMC or MCC group. A noncontact mapping system was deployed in the RVOT to identify origins of VPC/VT. Conventional activation and pace-mapping was performed to guide ablation. If ablation performed using 1 mode of catheter control was acutely unsuccessful, the patient crossed over to the other group. The primary endpoints were patients' and physicians' fluoroscopic exposure and times. Mean procedural times were similar between RMC and MCC groups. The fluoroscopic exposure and times for both patients and physicians were much lower in the RMC group than in the MCC group. Ablation was acutely successful in 14 of 15 patients in the MCC group and 10 of 15 in the RMC group. Following crossover, acute success was achieved in all patients. No major complications occurred in either group. During 22 months of follow-up, RVOT VPC recurred in 2 RMC patients. RMC navigation significantly reduces patients' and physicians' fluoroscopic times by 50.5% and 68.6%, respectively, when used in conjunction with a noncontact mapping system to guide ablation of RVOT VPC/VT.

The Application Of The 256-slice Multi-Detector Computed Tomography (MDCT) With Minimally Added Contrast Volume| technique for RVOT Ablation Planning In Brugada Syndrome

OBJECTIVE: To prove that the modified MDCT technique (single scan with minimally added contrast volume technique) can be used effectively in the right ventricular outflow tract (RVOT) and coronary artery structure demonstration and assessment before RVOT ablation with acceptable-readable image quality in cases of Brugada syndrome. MATERIALS AND METHODS: We retrospectively analyzed image quality of Brugada Syndrome patients who were planned for RVOT ablation and underwent 256-slice MDCT scanning using both conventional and modified techniques, i.e. minimally added contrast volume technique with iodinated contrast injection. The quality of the images obtained from MDCT using the modified technique was assessed in terms of acceptability and readability by the criteria of CT attenuation value of the region of interest (ROI) equal to or more than 250 HU (Hounsfield Unit). RESULTS: Between 2009 and 2012, a total of 13 Brugada syndrome patients (13 males mean age of 44.2 + 10.87 years old, mean weight 63.61 + 9.6 kg) who were planned for RVOT ablation were enrolled. All these patients underwent MDCT to demonstrate RVOT and coronary artery structure for pre-ablation planning. Nine of thirteen patients underwent 256-slice MDCT using the ECG-gated modified, minimally added contrast volume technique. All these nine patients provided the RVOT and coronary artery images that met acceptable-readable criteria, CT attenuation value &gt; 250 HU). Four of thirteen patients underwent 256-slice MDCT scan using conventional technique of CTA for pulmonary artery. RVOT images of two patients and the coronary artery images of another two patients who underwent 250-slice MDCT scan using ECG-gated conventional technique of CTA for pulmonary artery did not meet the acceptable-readable criteria (HU &lt; 250). The analysis showed the optimum contrast volume used in modified technique in our hospital was the value of calculated volume plus 10-15 ml and the total volume was not less than 60 ml for patients weighing 50-75 kilograms, regardless of heart rate, and we would recommend that it should not be less than 60 ml, otherwise image quality is detrimentally affected. Comparing to the MDCT, using the conventional technique in a separate scan to demonstrate RVOT and coronary artery, the exposure dose of radiation of the modified technique was as same as ECG-gated CTA for pulmonary artery scan only and the total contrast dose was also reduced by about one third. CONCLUSION: Using modified minimally added contrast volume technique with the 256-slice MDCT is very convenient and can be used effectively in demonstrating RVOT and coronary artery for RVOT ablation planning in Brugada’s syndrome cases with acceptable and readable image quality

Catheter ablation of right ventricular outflow tract tachycardia: a simplified remote-controlled approach

Manual mapping and ablation of right ventricular outflow tract (RVOT) tachycardia may be associated with cardiac perforation and complicated by mechanically induced ventricular extrasystoles (VESs). The aim of this study was to assess remote-controlled magnetic (RCM) mapping and ablation of RVOT ventricular tachycardia (VT)/VES utilizing a soft magnetic catheter. Mapping and ablation of RVOT VT/VES were performed using the magnetic navigation system (MNS, Niobe II, Stereotaxis, St Louis, MO) in conjunction with a cardiodrive motor unit (Stereotaxis). A soft magnetic catheter (Celsius RMT, 4 mm solid tip, Biosense Webster, Diamond Bar, CA) was navigated to the RVOT using a sequence of pre-installed magnetic vectors. The primary endpoint was defined as successful RCM VT/VES ablation. Other parameters observed included RCM RVOT accessibility, mapping-induced mechanical VES, fluoroscopy time, complications, and arrhythmia recurrence. Thirteen consecutive patients (mean age: 50 ± 14 years; 10 females, 6 RVOT VT) underwent RCM mapping and ablation. The RVOT was reached in all patients utilizing solely the MNS. Successful RCM RVOT ablation was achieved in {12 of 13} (92.3%) patients. Mean procedure and fluoroscopy times were 116.5 ± 48.9 and 7.5 ± 4.3 min, respectively. Catheter-induced VES during RVOT mapping were observed in {1 in 13} patients (7.7%, three VES). No complications occurred. During a mean follow-up of 252 ± 211 days, clinical arrhythmia recurrence was observed in {1 in 13} (7.7%) patients. Automatic RCM RVOT access is feasible, while RVOT mapping and ablation appear to be safe, fast, and effective. The soft magnetic catheter rarely induces mechanical VES.

Ablation of Nonsustained or Hemodynamically Unstable Ventricular Arrhythmia Originating From the Right Ventricular Outflow Tract Guided by Noncontact Mapping

Conventional activation or pacemapping is effective in guiding ablation of ventricular tachyarrhythmia originating from right ventricular outflow tract (RVOT). However, in selected patients with hemodynamically unstable or nonsustained tachycardia, noncontact mapping may be an effective alternative method to guide ablation in RVOT. Five patients with symptomatic hypotension during ventricular tachycardia (VT) or nonsustained tachyarrhythmia originating from the RVOT had radiofrequency ablation guided by noncontact mapping. All patients had a history of syncope and the tachyarrhythmias were refractory to antiarrhythmic therapy. Four patients had spontaneous sustained VT of a cycle length from 250 to 300 ms and one had symptomatic ventricular ectopic beats. Two patients were diagnosed to have arrhythmogenic right ventricular cardiomyopathy (ARVC). Sustained VT with hypotension was induced in two patients and nonsustained VT in three patients. Isopotential color maps were used to locate the earliest activation site of the tachyarrhythmia in RVOT. Three patients had tachyarrhythmia exit sites at the septal region and two at lateral region of RVOT. Low voltage area and diastolic activity were detected in the two patients with ARVC. Radiofrequency ablation guided by noncontact mapping was performed during sinus rhythm in all patients. The number of ablation attempts ranged from 1 to 14. After follow-up for 12 +/- 5.8 months, there was no recurrence of tachyarrhythmia and syncope in all five patients. Noncontact mapping is a safe and effective alternative method to guide ablation of hemodynamically unstable or nonsustained ventricular arrhythmia originating from RVOT.