Ventricular Ablation Research Articles

Non fluoroscopic ablation of different arrhythmic structures in an electrophysiology unit. Assessment of efficiency and security.

Electroanatomical mapping systems (EMS) reduce fluoroscopy dose for the ablation. Higher costs and longer procedure times are the drawbacks associated with EMS. Our objective was to validate the efficiency of the EMS. To demonstrate that using EMS is more efficient and as secure as the traditional system of ablation. From April 2013 to June 2018, all patients were included into two groups, according to the intention of ablation with or without fluoroscopy. Right, left, supraventricular and ventricular ablation were included. We compared procedure variables (fluoroscopy, radiofrequency and procedure times, ablation results, complication rates and costs of the procedure) that included material and detrimental effect of fluoroscopy. A total of 105 were included in the fluoroscopy group and 287 in the without fluoroscopy group. We found an important reduction in time and radiation dose in all the ablation procedures studied, without increasing the procedure time. No differences in ablation results nor complications rate were found. We found lower costs in the flutter ablation without fluoroscopy, similar costs in the right focal tachycardia ablation group and higher costs in the without fluoroscopy group for the AVNRT and left accessory pathway. When detrimental effect of fluoroscopy was added, all procedures without fluoroscopy were significantly more efficient than the ones performed with it. Ablation without fluoroscopy is a technique as safe and effective as the conventional technique. Our study suggests that the radiation dose delivered to the patient and staff might be reduced, without increasing the total procedure time, being even more efficient.

Acute effect of outflow tract premature ventricular complex ablation on QT dispersion, Tp-e interval and Tp-e/QT ratio

Background There is limited data regarding the effect of idiopathic premature ventricular complexes (PVC) on myocardial repolarisation. Most of PVC’s originate from right and left ventricular outflow tracts (RVOT and LVOT). Aim The aim of this study is to evaluate the acute effect of outflow tract PVC ablation on electrocardiographic repolarisation markers. Methods A total of 180 patients (49.2 ± 13.6 years, 74 male) without any exclusion criteria who had undergone outflow tract PVC ablation between 1 January 2015 and 1 November 2018 constituted our study population. Electrocardiographic recordings that had been obtained before and after ablation procedure on the same day were retrospectively evaluated for the QTc dispersion, Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio. Significance of difference between pre- and postablation values was tested. Results There was no significant difference regarding QTc dispersion between pre- and post-ablation state (36.5 ± 20.9 vs. 35.3 ± 16.4 ms, p: NS). However, Tp-e and Tp-e/QT values in all lateral precordial derivations were observed to decrease significantly after PVC ablation (in the respective order on derivation V5: 104.0 ± 21.6 ms vs. 91.1 ± 14.8 ms, p<.001 and 0.26 ± 0.05 vs. 0.23 ± 0.04, p<.001). Conclusions Based on these observations, it may be suggested that frequent outflow tract PVC’s increase transmural dispersion of repolarisation and this effect is attenuated by catheter ablation in the acute phase. Results of further prospective studies are required for evaluation of the long term effects of PVC ablation on myocardial repolarisation.

Ventricular Arrhythmias

Ventricular arrhythmias are common in all forms of heart disease and are an important cause of cardiac arrest and sudden death. Many ventricular arrhythmias are benign but may serve as a marker for underlying disease or its severity. Others are life threatening. The significance of an arrhythmia is determined by the specific characteristics of the arrhythmia and the associated heart disease, and these features guide evaluation and therapy. This review discusses various mechanisms and types of ventricular arrhythmias and management based on clinical presentation (including patients with symptomatic arrhythmia and increased risk of sudden death without arrhythmia symptoms). Genetic arrhythmia syndromes, such as abnormalities of repolarization and the QT interval, catecholaminergic polymorphic ventricular tachycardia (VT), and inherited cardiomyopathies, are discussed in depth. Under the rubric of management of ventricular arrhythmias, drug therapy for ventricular arrhythmias, implantable cardioverter-defibrillators (ICDs), and catheter ablation for VT are also covered. Tables chart out guideline recommendations for ICD therapy, drugs for the management of ventricular arrhythmias, and indications and contraindications for catheter ablation of ventricular arrhythmias. Electrocardiograms are provided, as well as management algorithms for ventricular arrhythmias based on patient presentation, and an algorithm for identifying patients with systolic heart failure and left ventricular ejection less than or equal to 35% who are candidates for consideration of an ICD for primary prevention of sudden cardiac death. This review contains 5 figures, 8 tables, and 61 references. Keywords: Ventricular arrhythmias, implanted cardioverter-defibrillator (ICD), Ventricular tachycardia (VT), Premature Ventricular Contractions (PVC), Myocardial Infarction (MI), Brugada syndrome, Arrhythmogenic right ventricular cardiomyopathy (ARVC), electrocardiographic (ECG)

Ventricular arrhythmia ablation lesions detectability and temporal changes on cardiac magnetic resonance.

Cardiac magnetic resonance (CMR) characteristics of ventricular radiofrequency ablation (RFA) lesions have only been incompletely defined. To determine the detectability and imaging characteristics of ventricular RFA lesions in an unselected patient cohort undergoing ventricular arrhythmia ablation. A retrospective chart review (n=249) identified 36 patients with either pre-/postablation CMR (n=14) or only postablation CMR (n=22). Ablation lesions could be identified in 50% (n=18) of patients. Nonvisualized lesions had more preexisting transmural late gadolinium enhancement(LGE) >75% at the ablation sites (21%vs 0.0%, P=.042), more prevalent ICD artifact (50%vs 0%, P=.001), and lower ejection fraction (35.8 ± 14.2%vs 45.3 ± 13.4%, P=.048). Early CMR imaging demonstrated a central "black" signal void (microvascular obstruction [MVO], n=12, 67%) up to 32 days post-RFA, whereas late imaging showed a homogenously "white" gadolinium enhancement pattern (n=6, 33%). MVO was only observed in nonfibrotic myocardium without preexisting LGE (n=12) but was not observed in the scar with preexisting LGE (n=3, P=.002) suggesting different wash-in/wash-out kinetics in scar/nonscar myocardium. Signal intensity (1909vs 2534, P=.009) and contrast-to-noise ratio (-7.8vs 16.3, P=.009) were significantly different between MVO and LGE lesions, respectively. Ventricular ablation lesions visualization is negatively affected by preexisting transmural scar, ICD artifact, and low ejection fraction. The transition of "black" MVO appearance to "white" LGE appearance on CMR occurs around 1 month following ablation, suggesting a change in histological characteristics of ablation lesions. This may affect the utility of CMR in the evaluation of the ventricular lesions, when undergoing real-time or repeat VT ablations.

Ventricular Arrhythmia Ablation With the Use of Non-Invasive ECG Imaging Technology

Ventricular Arrhythmia Ablation With the Use of Non-Invasive ECG Imaging Technology

HRS / EHRA / APHRS / LAHRS experts’ position paper on ventricular arrhythmia ablation in 2019

This article discusses some of the key issues outlined in the latest experts position paper regarding the ventricular ablation.

Use of a radiofrequency guidewire to simplify workflow for left atrium access: a case series.

Transseptal puncture (TSP) is widely used in catheter-based cardiac procedures to gain left atrial access, but its workflow has remained largely unchanged in the last 50years. This study evaluated the safety and efficacy of a novel, simplified technique for TSP with a radiofrequency (RF)-powered guidewire that eliminates multiple exchanges required with standard needles. TSP was performed in 84 patients undergoing left-sided procedures (72 atrial fibrillation ablations [32 RF, 40 cryoballoon], 4 atrial tachycardia ablations, 2 ventricular arrhythmia ablations, 6 left atrial appendage closure) utilizing a stiff, exchange length RF guidewire. Under fluoroscopic and echocardiographic guidance, the RF guidewire was used to facilitate septal puncture with RF energy and provide a rail for advancing catheters to the left atrium without exchange. All procedures were performed under general anesthesia or sedation. TSP was achieved in all patients with no complications. The RF guidewire allowed catheters to be tracked back up to the superior vena cava without exchange in cases where another dropdown was desired to locate a preferred puncture site. The stiffness of the wire provided adequate support to advance all sheaths to the left side regardless of outer diameter. TSP was performed safely and successfully for various left heart procedures with a RF guidewire that served as an RF transseptal device and a stiff guidewire. This allowed for a more efficient and potentially safer technique without the need for re-wiring or an over the wire sheath exchange. This provides substantial savings in both time and materials.

Continuation of Antiarrhythmics Following Ventricular Tachycardia Catheter Ablation

Continuation of Antiarrhythmics Following Ventricular Tachycardia Catheter Ablation

Novel Irrigated Temperature-Controlled Lattice Ablation Catheter for Ventricular Ablation: A Preclinical Multimodality Biophysical Characterization.

Ventricular tachycardia ablation is often limited by insufficient lesion creation. A novel radiofrequency catheter with an expandable lattice electrode has a larger surface area capable of delivering higher currents at a lower density to potentially increase lesion dimensions without overheating. This 8F bidirectional irrigated catheter (Sphere-9, Affera Inc) has a 9 mm spherical lattice tip ("lattice") with an effective surface area 10-fold larger than standard linear catheters. Nine surface thermocouples provide temperature feedback to a proprietary high-current generator operating in a temperature-controlled mode. Ex vivo phase: in 11 bovine hearts, unipolar ablation at 30, 60, and 120 seconds was compared between the lattice (Tmax60°C) and a standard linear irrigated-tip catheter (40 W) at contact force of 10 g. In 5 porcine hearts, bipolar ablation was compared between the catheters (Tmax60°C versus 40 W; 60 seconds). In vivo phase: in 9 swine, ventricular ablation at Tmax60°C versus 40 W was performed for 60 seconds. In addition, direct tissue temperature at 3- and 7-mm tissue depth was measured in a thigh muscle preparation. Ex vivo: lattice produced deeper lesions at 30, 60, and 120 seconds application duration (6.7±1.3 versus 4.8±1.2 mm; 8.3±1.4 versus 5.4±0.8 mm; 10.0±1.6 versus 6.1±1.6 mm, respectively, P≤0.001 for all). Bipolar lesions were deeper (15.8±4.1 versus 10.5±1.4 mm, P<0.001) and more likely to be transmural (80% versus 0%, P=0.002). In vivo: lattice produced deeper lesions (10.5±1.4 versus 6.5±0.8 mm, P≤0.001). Tissue temperature at 7 mm was higher with the lattice (+15.1±2.4°C; P<0.001). The steam-pop occurrence was lower with the lattice (total: 4% versus 18%, P=0.02; in vivo 0% versus 14.2%, P=0.13). This novel radiofrequency system produces larger ventricular lesions compared with standard irrigated catheters and at a lower risk of tissue overheating. This may improve the efficacy of ventricular tachycardia ablation procedures while reducing the number of applications and procedural duration.

Temperature-Controlled Radiofrequency Ablation Using Irrigated Catheters: Maximizing Ventricular Lesion Dimensions While Reducing Steam-Pop Formation.

The goal of this study was to examine the safety and efficacy of radiofrequency ablation (RFA) with irrigated catheters operated in a temperature-controlled mode for ventricular ablation. Techniques to increase RFA dimensions are associated with higher risk for steam-pops. A novel irrigated catheter with circumferential thermocouples embedded in its ablation surface provides real-time surface temperature data. This study hypothesized that RFA operated in a temperature-controlled mode may allow maximizing lesion dimensions while reducing the occurrence of steam-pops. RFA with an irrigated catheter incorporating surface thermocouples was examined in 6 swine thigh muscle preparations and 15 beating ventricles at higher (50 W/60 s, Tmax50oC) and lower (50 W/60 s, Tmax45oC) temperature limits. Biophysical properties, lesion dimensions, and steam-pop occurrence were compared versus RFA with a standard catheter operated in power-control mode at higher (50 W/60 s) and lower (40W/60 s) power, and additionally at high power with half-normal saline (50 W/60 s). In the thigh muscle preparation, lesion depth and width were similar between all groups (p=0.90 and p=0.17, respectively). Steam-pops were most frequent with power-controlled ablation at 50 W/60s (82%) and least frequent with temperature-controlled ablation at 50 W/60 s, Tmax45oC (0%; p<0.001). In the beating ventricle, lesiondepth was comparable between all RFA settings (p=0.09). Steam-pops were most frequent using power-controlled ablation at 50 W/60s (37%) and least frequent with temperature-controlled ablation at 50 W/60 s, Tmax45oC (7%; p<0.001). Half-normal saline had no incremental effect on lesion dimensions at 50W in either the thigh muscle or the beating heart. RFA using a novel irrigated catheter with surface thermocouples operated in a temperature-controlled mode can maximize lesion dimensions while reducing the risk for steam-pops.

1831 Pericardioesophageal Fistula Formation Following Ventricular Tachycardia Ablation: Case Presentation With Discussion of Incidence and Treatment

INTRODUCTION: Cardioesophageal fistulas following radiofrequency ablation (RFA) for atrial fibrillation is a rare but increasingly recognized complication of the procedure with an estimated annual incidence rate of 0.03-0.04%. While atrioesophageal fistulas require surgical management, pericardialesophageal fistulas can often be conservatively managed. The fistula formation is believed to be due to the inflammatory cascade initiated from thermal injury and subsequent degradation of tissue boundaries. Though reported following atrial ablation, it has not been reported with ventricular ablation. Here, we present a case of pericardioesophageal fistula following RFA for ventricular tachycardia. CASE DESCRIPTION/METHODS: 61-year-old male presented to the emergency department complaining of fever, chest pain and dyspnea following inferolateral wall ablation and scar homogenization two weeks prior. He had a history of cardiomyopathy with AICD placement and refractory ventricular tachycardia due to ischemic heart disease. CT angiogram ruled out PE but demonstrated a pneumopericardium, later confirmed by echocardiogram. He subsequently developed signs of sepsis with profound hypotension requiring pressor support and underwent a pericardial window and indwelling pericardial drain placement. Due to fibrinous septations, tPA was infused to facilitate the purulent drainage. Fluid cultured from the pericardial window grew Staphylococcus epidermis and gram-negative bacilli. EGD was preformed with a 2 cm diameter pericardioesophageal fistula 4 cm above the GE junction and 36 cm distal to the incisors. He had a fully covered esophageal stent placed given poor nutritional status and poor surgical candidacy. His hospital course was further complicated by vent dependent respiratory failure, acute renal failure, recurrent DVTs with an upper GI bleed due to a contained rupture of an esophageal hematoma necessitating the placement of an IVC filter. Follow-up endoscopy two months following placement demonstrated stent migration but a healed pericardioesophageal fistula. DISCUSSION: This case demonstrates the importance of considering pericardioesophageal fistula as a complication of ventricular ablation. Treatment options are variable and they are often managed endoscopically as a temporizing measure until surgery can be safely performed. Here, we report the first case, to our knowledge, of pericardioesophageal fistula following ventricular ablation successfully managed with supportive measures.

P3816Cost-effectiveness of ventricular tachycardia catheter ablation: limitations in the current trial evidence base

Abstract Introduction Randomised clinical trials (RCTs) have suffered from criticisms including a lack of generalisability as well as a lack of cost-effectiveness analysis of the different interventions being studied. Such analyses are used by organisations including the UK's National institute for Health and Care Excellence (NICE) to inform system-level decisions regarding which treatments are funded. There is the potential for a growing chasm to exist between what is the latest innovation in cardiology and what can be afforded. Purpose To evaluate the cost-effectiveness of ventricular tachycardia (VT) catheter ablation versus anti-arrhythmic drug (AAD) therapy in ischemic heart disease. Methods A decision-analytic Markov model was used to calculate the costs and health outcomes of catheter ablation or AAD treatment of VT for a hypothetical cohort of patients with ischaemic cardiomyopathy andan implantable cardioverter defibrillator (ICD). Model inputs where informed using RCT-level evidence [Table 1] wherever possible. Costs were calculated from a UK perspective. Results Catheter ablation vs. AAD therapy had an incremental cost-effectiveness ratio (ICER) of £144,150 (€161,448) per quality adjusted life year (QALY) gained, over a five-year time horizon. The ICER for a ten-year time horizon was £75,074 (€84,083) and £69,986 (€78,384) over the cohort's lifetime. Using probabilistic sensitivity analyses to account for model parameter uncertainty, the likelihood of catheter ablation being cost-effective was only 11%, assuming a willingness to pay threshold of £30,000 used by the NICE [Figure 1]. Table 1. Summary of RCT level source data used to inform Markov model inputs Name of trial SMASH VT VTACH SMS CALYPSO VANISH VISTA Sample size 128 110 111 27 259 118 Mean age 67 66 67 64 68 66 Control AAD AAD AAD AAD AAD Clinical ablation Intervention Ablation Ablation Ablation Ablation Ablation Substrate ablation Length of follow up 22 months 24 months 28 months 6 months 28 months 12 months Mortality (%) 11% [AAD] 7% [AAD] 19% [AAD] 14% [AAD] 28% [AAD] 15% [C-ablation] vs. vs. vs. vs. vs. vs. 9% [Ablation] 10% [Ablation] 17% [Ablation] 15% [Ablation] 27% [Ablation] 9% [S-Ablation] Readmission (%) 19% [AAD] 55% [AAD] 44% [AAD] 50% [AAD] 31% [AAD] 32% [C-ablation] vs. vs. vs. vs. vs. vs. 12% [S-ablation] 6% [Ablation] 33% [Ablation] 39% [Ablation] 38% [Ablation] 25% [Ablation] Cost-effectiveness acceptability curve Conclusion Catheter ablation of VT is unlikely to be cost-effective compared with AAD therapy alone in patients with ischaemic cardiomyopathy implanted with an ICD based on pooled trial evidence. However, better designed studies incorporating detailed and more frequent quality of life assessment are needed to advise health policy in this field and to provide more informed cost-effectiveness analyses. Acknowledgement/Funding NIHR Academic Clinical Fellowship

P992Incidence, predictors, and success of ventricular tachycardia catheter ablation in arrhythmogenic right ventricular cardiomyopathy (ARVC): A long-term cohort study from the Nordic ARVC registry

Abstract Background Catheter ablation may reduce ventricular tachycardia (VT) burden in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients. However, little is known about factors predicting need for ablation and various outcomes have been reported. Purpose We sought to investigate predictors and use of VT ablation and to evaluate the post-procedural outcome in ARVC patients. Methods We studied 435 patients from the Nordic ARVC registry including 220 probands with definite ARVC according to the 2010 task force criteria and 215 mutation-carrying relatives identified through cascade screening. Patients were followed until first-time VT ablation, death, heart transplantation, or January 1st 2018. Additionally, patients undergoing VT ablation were further followed from the time of ablation for recurrent ventricular arrhythmias. Results Cumulative use of VT ablation was 4% (95% CI 3%-6%) and 11% (95% CI 8%-15%) after 1 and 10 years. All procedures were performed in probands in whom the cumulative use was 8% (95% CI 5%-12%) and 20% (95% CI 15%-26%). In adjusted analyses restricted to probands, only young age predicted need for ablation. In patients undergoing ablation, risk of recurrent arrhythmias was 59% (95% CI 44%-71%) and 74% (95% CI 59%-84%) 1 and 5 years after the procedure. Despite high recurrence rates, the burden of ventricular arrhythmias was reduced after ablation (p=0.0042). Young age, use of several antiarrhythmic drugs and inducibility to VT immediately after ablation were associated with an unfavorable outcome. Conclusions Twenty percent of ARVC probands developed a clinical indication for VT ablation within 10 years after diagnosis whereas mutation-carrying relatives were without such need. Although the burden of ventricular arrhythmias decreased after ablation, risk of recurrence was substantial.

P1883Arrhythmias in transplanted hearts: Lessons from Europes largest cohort of patients who underwent orthotopic heart transplantation

Abstract Introduction Cardiac arrhythmias are regulary seen in patients following orthotopic heart transplantation (OHT). So far, there is no data available about the prevalence in a large cohort. Methods We retrospectively screened our database for subjects with OHT who received inpatient or outpatient treatment in our center between January 2000 and December 2018. All these patients were carefully reviewed with special attention to rhythm disturbances after successful transplantation. Results We identified a total number of 1890 subjects with history of OHT being treated in our center during the pre-defined time-period. The prevalence of supraventricular tachycardias was as follows: atrial fibrillation/atypical flutter and atrial ectopy 10%, AV-node-re-entry tachycardia 3%, typical atrial flutter 2% and higher degree AV-Block or Sick-Sinus-Syndrom (SSS) was 6%. Sustained ventricular tachycardia or ventricular premature contractions were present in 2%. Regarding the patients with arrhythmias, 13% received catheter ablation for arrhythmias, thereof 53% an atrial ablation (24% left atrial ablation), the remainder received a ventricular ablation. Conclusion In this very large cohort and following a long observational time, there was a higher incidence of atrial arrhythmias in patients following OHT as reported in healthy subjects with an emphasis on atrial fibrillation and flutter. This data gives a valuable background information on morbidity following OHT.

Nationwide survey on the current practice of ventricular tachycardia ablation.

We performed a nationwide survey on the current practice of ventricular tachycardia catheter ablation in Italy during the year 2016. Among 145 operators participating in the survey, 58 (40.0%) did not perform any ventricular tachycardia ablation in 2016. Among those performing ventricular tachycardia ablation, 9 operators (6.2%) performed only right ventricular endocardial catheter ablation, 52 (35.9%) performed endocardial catheter ablation both in the right and left ventricle (LV) and 26 (17.9%) performed both endocardial and epicardial LV catheter ablations. Seventy operators (89.7%) among the 78 performing LV and epicardial ablations treated patients with ischemic cardiomyopathy; ablations in the setting of other causes were less frequently performed. The following were considered as minimum requirements for ventricular tachycardia ablation: presence of a three-dimensional mapping system (120 operators, 82.8%), ICU in the hospital (118 operators, 81.4%), operator's training in high volume centers (93 operators, 64.1%). Twenty-eight operators (19.3%) performed catheter ablation in patients with electrical storm only after hemodynamic stabilization, 41 operators (28.3%) also during the acute phase and 9 operators (6.2%) never performed catheter ablation in electrical storm patients; the remaining 67 operators did not perform ventricular tachycardia ablation at all, or performed ablations only in the right ventricle. The present survey provides a snapshot of the current invasive treatment of ventricular tachycardia by catheter ablation. The procedure, especially in the setting of ischemic cardiomyopathy, is performed nationwide. Complex cases, including those with electrical storm, should be managed within a preestablished integrated network of regional referral centers able to transfer patients as soon as possible.

Effect of ventricular premature catheter ablation on diastolic function in elderly patients

Objective To observe whether catheter ablation for ventricular premature complexes (PVC) has an effect on ventricular diastolic function in elderly patients. Methods Elderly patients older than 65 years of age who underwent catheter ablation from March 2012 to May 2015 for idiopathic ventricular premature complexes were enrolled.Preoperative echocardiography was performed using E/e′ for left ventricular diastolic function and venous brain natriuretic peptide (BNP) levels were measured.All patients underwent catheter ablation under the guidance of a three-dimensional mapping system.Cardiac ultrasound and BNP levels were repeated 6 months after ablation, and 24-hour electrocardiogram was performed to confirm ventricular premature complexes. Results There were a total of 89 patients with idiopathic ventricular premature complexes (PVC) who underwent catheter ablation.81 cases were successed at 6 months, with a success rate of 91.0%.At 6 months after ablation, the E/e′ values were significantly lower ((15.3±5.2) vs (10.2±3.2), (P 0.05). Conclusion The number of premature ventricular beats is associated with left ventricular diastolic function, and ventricular premature catheter ablation can improve left ventricular diastolic function in elderly PVC patients. Key words: Ventricular premature complexes; Catheter ablation; Diastolic function; Brain natriuretic peptide; The aged

Development of a novel ablation hood to prevent systemic embolization of microbubbles and particulate emboli.

Atrial fibrillation ablation results in microbubbles and particulate emboli formation. We aimed to develop and test the early feasibility of a novel ablation hood to contain microbubbles and particulate emboli with the ultimate goal of preventing systemic embolization. In seven canines, we developed, iterated, and tested a novel retractable hood that can cover the catheter-tissue ablation site. The number and volume (nL) of microbubbles formed during ablation with and without the hood was measured using an extracorporeal circulation loop. Wilcoxon's signed-rank test was used to compare the number of bubbles detectedwith and without the hood. The hood reduced systemic embolization of microbubbles in 21/28 (75%) of ablations. Both atrial and ventricular ablations showed a statistically significant reduction in bubble number (476 ± 811 without hood vs 173 ± 226 with hood, p = 0.02; 2669 ± 1623 without hood vs 1417 ± 970 with hood, p = 0.04, respectively) and bubble volume (3.3 ± 7.6nL without hood vs 0.2 ± 0.56nL with hood, p = 0.006; 6.1 ± 5.2nL without hood vs 1.9 ± 1.4nL with hood, p = 0.05, respectively). Use of a novel hood to cover the ablation catheter at the site of catheter-tissue contact has the potential to provide a means to reduce systematic embolization of microbubbles. Further work is required to examine particulate emboli, but these data show the early feasibility of this design concept.

P391Predicting the success of ventricular ablation: the role of sympathetic perfusion/innervation mismatch

P391Predicting the success of ventricular ablation: the role of sympathetic perfusion/innervation mismatch

Surgical ablation of ventricular tachycardia in patients with repaired tetralogy of Fallot†.

Life expectancy of patients with repaired tetralogy of Fallot is normal until adulthood, when it becomes burdened by major complications such as cardiac arrhythmias and heart failure. Ventricular tachycardia (VT), associated with electrical conduction abnormalities in anatomical isthmuses, is the most common complication and is refractory to medical therapy. The arrhythmogenic sources can be surgically ablated during reoperations for pulmonary valve incompetence. The purpose of our study is to evaluate the safety and effectiveness of surgical radiofrequency ablation during PVR and its long-term impact on the occurrence of cardiac events. A total of 118 patients with repaired tetralogy of Fallot underwent reoperation for pulmonary valve regurgitation in IRCCS-Policlinico San Donato between January 2002 and February 2016. Twenty patients with risk factors for ventricular arrhythmia underwent EP testing and were found positive. The mean QRS duration was 178 ms. Right ventricular dysfunction was present in all the patients, and 20% had associated tricuspid regurgitation. The cohort (N = 20), with positive EP study, underwent pulmonary valve replacement and concomitant intraoperative ventricular surgical radiofrequency ablation, targeting the slow conducting isthmuses identified during preoperative electroanatomical mapping. All patients were reviewed at 1 month, 3 months and 6 months with clinical evaluation, echocardiography, ECG and implantable cardioverter-defibrillator interrogation. At 6 months, a postoperative electrophysiological study was performed in all patients, and a cardioverter defibrillator was implanted as primary preventive measure in patients with residual inducible VT. Pulmonary valve replacement and surgical ventricular radiofrequency ablation were performed in all cases. One patient died while on V-V extracorporeal membrane oxygenation (ECMO) due to respiratory failure. There was no late mortality. Follow-up was complete with a median of 6.5 years. During the postoperative EPS study, inducible VT was found in 15.7% of patients who received an implantable cardioverter-defibrillator, whereas VT could no longer be induced in the remaining patients. No procedure-related complication was observed, and freedom from ventricular arrhythmia was 94% and 89.5% at 1 year and 5 years, respectively. Pulmonary regurgitation and right ventricular dysfunction correlate with VT and SCD, but valve replacement alone does not reduce the risk of ventricular tachyarrhythmias. Intraoperative ventricular ablation during reoperation for pulmonary regurgitation prevents the occurrence of ventricular arrhythmias in the early and medium term. Accordingly, this technique may be proposed as a safe associated procedure in selected patients.

Characterization of edema after cryo and radiofrequency ablations based on serial magnetic resonance imaging.

Radiofrequency (RF) and cryoablation are routinely used to treat arrhythmias, but the extent and time course of edema associated with the two different modalities is unknown. Our goal was to follow the lesion maturation and edema formation after RF and cryoablation using serial magnetic resonance imaging (MRI). Ventricular ablation was performed in a canine model (n = 11) using a cryo or an irrigated RF catheter. T2-weighted (T2w) edema imaging and late gadolinium enhancement (LGE)-MRI were done immediately (0 day: acute), 1 to 2 weeks (subacute), and 8 to 12 weeks (chronic) after ablation. After the final MRI, excised hearts underwent pathological evaluation. As a result, 45 ventricular lesions (cryo group: 20; RF group: 25) were evaluated. Acute LGE volume was not significantly different but acute edema volume in cryo group was significantly smaller (1225.0 ± 263.5 vs 1855.2 ± 520.5 mm3 ; P = 0.01). One week after ablation, edema still existed in both group but was similar in size. Two weeks after ablation there was no edema in either of the groups. In the chronic phase, the lesion volume for cryo and RF in LGE-MRI (296.7 ± 156.4 vs 281.6 ± 140.8 mm3 ; P = 0.73); and pathology (243.3 ± 125.9 vs 214.5 ± 148.6 mm3 ; P = 0.49), as well as depth, was comparable. When comparing cryo and RF lesions of similar chronic size, acute edema is larger for RF lesions. Edema resolves in both cryo and RF lesions in 1 to 2 weeks.