Irrigated Ablation Catheter Research Articles

Radiofrequency Catheter Ablation Targeting the Vein of Marshall in Difficult Mitral Isthmus Ablation or Pulmonary Vein Isolation.

The ligament of Marshall may hinder the creation of mitral isthmus (MI) block or pulmonary vein (PV) isolation (PVI) in radiofrequency (RF) catheter ablation of atrial fibrillation (AF). We aimed to assess the benefit of RF ablation targeting the vein of Marshall (VOM) in failed cases of MI block or PVI. We reviewed the medical records of patients who underwent RF ablation targeting the VOM after failed MI ablation or left PVI using the conventional method, which included circumferential point-by-point ablation around the PV antrum and carina for PVI, and endocardial MI and epicardial distal coronary sinus (CS) ablation for MI block. The VOM was identified by using selective VOM venography with an external irrigation RF ablation catheter. RF ablation targeting the VOM was performed with RF application at the ostium of the VOM inside the CS or at the endocardial region facing the VOM course. During the set period, CS venography was performed in 42 patients after failure of left PVI (n = 5) or MI block (n = 37). Under CS venography, the VOM was visualized in 22 of 42 patients (MI = 19 and PVI = 3). During selective venography of the VOM, no procedure-related complication was observed. RF application targeting the VOM successfully achieved MI block in 13 patients (68.4%) and PVI in 2 patients (66.7%). Selective VOM venography using an irrigated ablation catheter is feasible and safe. RF ablation targeting the VOM may provide additional benefit in failed cases of MI block or PVI.

Abstract 13166: Externally Irrigated Radiofrequency Ablation With Low Osmolarity Irrigant for the Treatment of Cardiac Arrhythmias

Introduction: Certain cardiac arrhythmias arise from deep or thick myocardium and may be refractory to standard external irrigated ablation. Externally irrigated ablation (EIA) is generally performed with normal saline (NS) as the infusing irrigant. Recent data suggest that larger ablation lesions can be created by decreasing the irrigant osmolarity. Hypothesis: We sought to evaluate the use of half normal saline (HNS) as the irrigant in externally irrigated ablation under ex vivo and in vivo conditions. Methods: Bovine myocardium was placed in a circulating saline bath in an ex vivo model. Two externally irrigated ablation catheters were oriented across from each other, with myocardium in between. Sequential unipolar ablations with HNS were performed at 50 Watts for 60 seconds, and ablation lesions were compared to using NS or HNS irrigation. In addition, a retrospective analysis was performed of all ablations using HNS completed at the University of Colorado from 2015-2016. Results: In vivo porcine ablations with HNS irrigation generated larger lesions, compared to control ablations using standard NS irrigation, and there was no increased incidence of steam pops (Figure 1). Clinically, 7 cases were identified that utilized HNS as the irrigant in EIA for refractory arrhythmias (1 atrial tachycardia, 6 VT/PVC cases). Acute success was achieved in 7/7 of procedures, with no recurrences at a mean follow up of 109 days. There were no complications (Figure 2). Conclusions: By decreasing irrigant osmolarity and charge density in EIA through the use of HNS, larger ablation lesions can be created to target deep arrhythmia circuits refractory to standard ablation.

16-30: Radiofrequency ablation of right-sided accessory pathways in children: how have 3-D mapping systems and cool-tip catheters changed success, fluoroscopy time and recurrence?

Aims: Catheter ablation of right-sided accessory pathways (AP) still presents a challenge with lower success and higher recurrence rates. We evaluated the use of a 3-dimensional mapping (3-D) system in combination with irrigated-tip ablation catheter (ITC) compared to a conventional fluoroscopic/non- irrigated tip catheter approach in patients <18 years undergoing radiofrequency ablation (RFA) for right-sided APs with regard to acute procedural success, fluoroscopy time/dosage, safety and recurrence rate. Methods and results: A retrospective analysis of all patients <18 years undergoing RFA for right-sided APs from May 2004 to December 2014 was performed. In 2010, our approach had changed from conventional fluoroscopy/non- irrigated tip catheters to the use of a 3-D mapping system in combination with irrigated- tip catheter ablation. A total of 105 children (56.2% male) age 4.0–17.9 years (mean 13.4 ± 2.9 years) with 107 right-sided accessory pathways were included in the study. In 15 patients, congenital heart disease was present (Ebstein anomaly n = 8). Preexcitation was overt (n = 75) or concealed (n = 32). AP localization was right free wall (n = 54) or septal (n = 53). The most common AP site was the posteroseptal region (44.9%). Patients were divided into 2 groups. Group 1 included 53 patients (50.5%) undergoing RFA with the use of a 3D mapping system and ITC whereas Group 2 consisted of 52 patients (49.5%) with a conventional fluoroscopic approach/non- irrigated ablation catheter. Study endpoints were acute procedural success rate, fluoroscopy time/dosage, safety and recurrence rate. Radiofrequency catheter ablation was performed acutely successful in 101 of 107 accessory pathways (94.3%). Acute success rates did not differ between Group 1 (94.3%) and Group 2 (94.2%). Procedure time was shorter in the 3-D/ITC Group (mean 129.4 min versus mean 170.9 min; p = 0.001). Fluoroscopy time (mean 12.8 min vs. mean 22.9 min; p = 0.004) and fluoroscopy dose (mean 329.7 cGycm2 vs. mean 756.3 cGycm2 p = 0.009) were also lower in the 3-D/ITC group compared to the conventional group. Overall mortality was 0%. Complications occurred in 5 patients (4.8%) with one major complication in Group 2 (pericardial haemorrhage). Minor vascular complications at the puncture site were observed in 3 patients (2.9%). One patient from Group 2 with a midseptal location pathway developed first-degree atrioventricular block. AP recurrence after an initially successful ablation was observed in 12/101 cases (11.8%). The use of a 3-D system/ITC was associated with a significantly lower AP recurrence rate (6.0% Group 1 vs. 18.4% Group 2; p < 0.05). Conclusion: The use of a 3-D mapping system in combination with irrigated-tip catheter ablation (3-D/ITC) for the ablation of right- sided accessory pathways in children and adolescents is associated with a reduced procedure and fluoroscopy time as well as fluoroscopy dosage. The recurrence rate is significantly lower using 3-D/ITC compared to a conventional approach. The combination of 3-D mapping and irrigated tip catheter ablation might therefore be considered as preferred approach for the ablation of right-sided APs in this age group.

Acute and Mid-Term Results after Pulmonary Veins Isolation Using a Novel Circular Irrigated Multielectrode Mapping and Ablation Catheter (nMARQ)

Background: Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation in both paroxysmal and persistent AF. However, this procedure is still challenging and time consuming. Objective: The aim of this study was to present our approach for PVI using a novel circular irrigated multielectrode mapping and ablation catheter (nMARQTM) and to present acute and mid-term results. Methods: The study included 31 consecutive patients with symptomatic AF (4 had persistent and 27 had paroxysmal AF) who underwent PVI using the nMARQTM catheter. Circular ablation was guided by CT image integrated into fast anatomical map and by intra cardiac echo. Isolation of pulmonary veins was identified using the nMARQTM catheter if it was possible to advance it into the veins, otherwise Lasso catheter was used. Patients were followed up to 20 months. Results: PVI was achieved in 119 (98%) out of 121 pulmonary veins identified, and final PVI was obtained in 30 (97%) out of 31 patients. Lasso catheter was needed for PVI confirmation in 16 (52%) patients. Touch up ablation using standard catheter guided by Lasso catheter was needed in 4 (13%) patients. Pericardial tamponade occurred in 1 patient who was treated with pericardiocentesis. No other major complications were detected. During follow-up (mean 15.9 ± 3.6 months, range 9 - 20 months), 4 (13%) patients had recurrence of atrial tachyarrhythmia. Conclusion: PVI using the novel nMARQTM catheter is safe with good acute and mid-term efficacy. Long term follow up trials are needed.

Renal Sympathetic Denervation in Mild to Moderate Chronic Kidney Disease Patients with Chronic Heart Failure Refractory to Cardiac Resynchronization Therapy: A Safety Evaluation Study

Background: Heart failure (HF) is a challenging disease to control. Chronic overactivation of the sympathetic nervous system occurs early in HF and chronic kidney disease (CKD). The aim of this study was to evaluate the safety and effects of renal sympathetic denervation (RSD) in reducing lesions on the heart and kidneys in patients with CKD and HF refractory to cardiac resynchronization therapy (CRT). Methods and results: Twenty-one patients were included and treated with a standard irrigated cardiac ablation catheter. RSD was performed by a unique operator. All the patients included in the study had HF in functional New York Health Association (NYHA) class III, were refractory to CRT, and had mild-to-moderate CKD. Data were obtained at baseline, and at 6 and 12 months of follow-up. RSD was safe and feasible to perform in this population. No changes in blood pressure were observed during this period. At baseline, patients walked 172.4 ± 26.4 m during a 6-minute walk test, increasing to 209.4 ± 29.1 m at 12 months post RSD (p<0.001). All echocardiographic parameters evaluated improved at 6 (p<0.001) and 12 months (p<0.001) after RSD. Estimated glomerular filtration rate improved from 67.4 ± 20.5 mL/min/1.73 m2 at baseline to 87.8 ± 17.9 mL/min/1.73 m2 at 12 months post procedure (p<0.001). At 12 months after RSD, 42% of patients were in functional NYHA class I, 50% were in functional class II, and 8% remained in functional NYHA class III. Conclusions: RSD seemed to be safe, feasible, and effective, resulting in an improvement in echocardiographic parameters, 6-minute walk test distance, renal function, and functional NYHA class in mild-to-moderate CKD patients with HF refractory to CRT.

Reduction of Fluoroscopic Exposure Using a New Fluoroscopy Integrating Technology in a 3D-Mapping System During Pulmonary Vein Isolation With a Circular Multipolar Irrigated Catheter.

Pulmonary vein isolation (PVI) is a cornerstone therapy in patients with atrial fibrillation (AF). With increasing numbers of PVI procedures, demand arises to reduce the cumulative fluoroscopic radiation exposure for both the physician and the patient. New technologies are emerging to address this issue. Here, we report our first experiences with a new fluoroscopy integrating technology in addition to a current 3D-mapping system. The new fluoroscopy integrating system (FIS) with 3D-mapping was used prospectively in 15 patients with AF. Control PVI cases (n = 37) were collected retrospectively as a complete series. Total procedure time (skin to skin), fluoroscopic time, and dose-area-product (DAP) data were analyzed. All PVI procedures were performed by one experienced physician using a commercially available circular multipolar irrigated ablation catheter. All PVI procedures were successfully undertaken without major complications. Baseline characteristics of the two groups showed no significant differences. In the group using the FIS, the fluoroscopic time and DAP were significantly reduced from 571 ± 187 seconds versus 1011 ± 527 seconds (P = 0.0029) and 4342 ± 2073 cGycm(2) versus 6208 ± 3314 cGycm(2) (P = 0.049), respectively. Mean procedure time was not significantly affected and was 114 ± 31 minutes versus 104 ± 24 minutes (P = 0.23) by the FIS.The use of the new FIS with the current 3D-mapping system enables a significant reduction of the total fluoroscopy time and DAP compared to the previous combination of 3D-mapping system plus normal fluoroscopy during PVI utilizing a circular multipolar irrigated ablation catheter. However, the concomitant total procedure time is not affected. Thus, the new system reduces the radiation exposure for both the physicians and patients.

Abstract 16285: Routine Use of 3D Mapping and Irrigated Ablation Improves Outcomes of Pulmonary Vein Antral Isolation Among Patients With Persistent AF

Bckground: Pulmonary Vein Antrum Isolation (PVAI) is a widely accepted treatment option in Atrial Fibrillation (AF). However, despite procedural advancements, post-PVAI AF recurrences remain a common challenge. We thought to investigate whether the addition of routine 3D electroanatomical mapping and routine use of irrigated ablation catheters (IC) vs 8 mm tip catheters made an impact on the outcomes of PVAI guided by intracardiac echocardiography (ICE) and a decapolar circular mapping catheter (CMC) alone. Methods: Patient and procedural data were collected for 884 AF consecutive patients undergoing PVI at a single Canadian center during 2004 - 2014 (469 patients in 2004-2009, Group 1vs. 415 patients in 2010-2014, Group 2). Group 1 patients received PVAI guided by ICE and CMC. All Group 2 patients had PVAI guided by ICE, CMC and 3D mapping with the use of irrigated tip ablation catheters. Mean ages for Groups 1 and 2 were = 58.6 ± 10.0 and 61.0 ± 10.7 years respectively (p= 0.001). Mean follow up time was 17.1 ± 18.8 months for Group 1 and 14.1± 9.7 months for Group 2 (p=0.003). ECG and ambulatory monitoring was performed at 1, 3, 6, and 12 months. Recurrences ≤ 3 months post-PVI were considered Early (ER), while recurrences after 3 months post-PVI were considered Late (LR). Using survival analysis, rates of LR stratified by AF type [Paroxysmal AF (PAF) vs. Non-PAF (NPAF)] were compared between the two cohorts Results: ER rate was lower in Group 2 vs. Group 1 (36.8% vs. 44.7%, P=0.05) in patients with PAF and for those with NPAF (54.8% vs. 66.9%, P=0.03). LR rates did not differ between the Groups among PAF patients (62.5% in Group 1 vs. 57.3% in Group 2, P=0.16), but improved significantly for the NPAF patients (55.6% in Group 1 vs. 37.9% in Group 2 , P=0.002). Conclusion: Late recurrence of AF post-PVI has dramatically improved since 2010 for patients with persistent AF following routine addition of 3D mapping to ICE and CMC, while substituting an irrigated for an 8mm ablation catheter.

Usefulness of intracardiac echocardiography during pulmonary vein isolation with the novel multipolar irrigated ablation catheter (nMARQ™).

Previous studies reported the usefulness of an irrigated circular radiofrequency ablation catheter (nMARQ(TM), Biosense Webster) for pulmonary vein isolation (PVI). We evaluated the role of intracardiac echocardiography (ICE) to optimize the manipulation of nMARQ(TM) catheter. Thirty-seven patients (pts), (mean age 55 ± 12 years; 28 males) were enrolled to perform PVI. All pts underwent PVI with the nMARQ(TM) catheter. In 20 pts (group 1), we utilized ICE to guide nMARQ(TM) catheter positioning at the PV ostia; in the other 17 pts (group 2), nMARQ(TM) catheter was positioned at the PV ostia guided by fluoroscopy and TissueConnect(TM) technology. Radiofrequency (RF) applications were significantly lower in group 1 compared to group 2 [left PVs: 6 (range 3 to 12) in group 1 and 12 (range 5 to 16) in group 2 (p < 0.001); right PVs: 7 (range 4 to 14) in group 1 and 10 (range 5 to 16) in group 2 (p = 0.04)]; similarly regarding the time of RF delivery [left PVs: 318 ± 194 s in group 1 vs. 542 ± 104 s in group 2 (p < 0.001); right PVs: 410 ± 270 s in group 1 vs. 550 ± 156 s in group 2 (p = 0.05)]. Fluoroscopy time (23 ± 9 min vs. 28 ± 5 min; p = 0.05), procedural time (83 ± 23 min vs. 160 ± 42 min; p < 0.001), and radiation dose (109 ± 20 Gy/cm(2) vs. 127 ± 29 Gy/cm(2); p = 0.04) were significantly lower in group 1 compared to group 2. ICE might be a useful tool to guide nMARQ(TM) catheter position in the left atrium during atrial fibrillation (AF) ablation procedures.

Efficacy evaluation of renal denervation with a standard irrigated cardiac ablation catheter in a 44 years old male with refractory hypertension: a case report

Background: Central hemodynamics and arterial stiffness evaluations are important for cardiovascular risk. The behavior of central blood pressure (CBP), and pulse wave velocity (PWV) during 24 hours is not well known. Objective: To investigate CBP and PWV in relation to brachial BP in 24 hours, awake and sleep periods in normotensive and untreated hypertensive individuals from 18 to 50 years old. Methods: A total of 104 subjects (60 females (57.7%) and 44 males (42.3%)), 48 (46.2%) individuals between 18 and 35 years old and 56 (53.8%) individuals between 36 and 50 years old were included. Exclusion criteria were: use of antihypertensive drugs, body mass index 35 kg/m, eGFR <60 ml/min, diabetes and smoking. All were submitted to clinical and laboratory evaluation; office BP was measured using a oscillometric sphygmomanometer OMRON, model HEM-705CP, and 24h monitoring brachial BP, CBP, Augmentation Index (AIx) and PWV were obtained with the Mobil-O-Graph equipment (DINA MAP cardios ESI GmbH, Stolberg, Germany). Results: The study population showed a mean age of 36.99 8:53 years, BMI 25.80 3.82kg/m, and prevalence of hypertension 32.7%. Office BP means were: systolic BP (SBP) 130.45 17.28mmHg and diastolic BP (DBP) 80.11 10.39mmHg. Awake brachial was lower than office BP (p<0.001, difference between office SBP and awake SBP 1⁄4 11.17 14.21mmHg, and of office DBP and awake DBP 1⁄4 1.76 7.88mmHg). Systolic CBP was lower than brachial SBP in 24h, and awake and sleep periods (p<0.001, differences were 8.49 2.72mmHg, 9.35 3.42mmHg and 5.68 2.96mmHg between brachial SBP and systolic CBP in 24h, awake and sleep periods, respectively). Conversely, diastolic CBP was slightly higher than brachial DBP in 24h, awake and sleep periods (p<0.001, differences were 0.91 1.59mmHg, 1.55 1.78mmHg and 0.82 1.53mmHg between brachial SBP and diastolic CBP in 24h, awake and sleep periods, respectively). There were significant reductions between awake and sleep periods for systolic and diastolic CBP, for AIx and for PWV (p<0.001, differences were 5.62 7.13mmHg, 10.14 7.01mmHg, 3.85 9.07mmHg and 0.19 0.25mmHg for systolic CBP, diastolic CBP, AIx, and PWV, respectively). Conclusion: In normotensive and untreated hypertensive young adults, awake brachial BP was lower than office BP and systolic CBP means were lower than brachial BP, but diastolic CBP means were higher than brachial DBP. Reductions between awake and sleep periods were observed in the CBP, AIx and PWV means, similarly to what is observed with brachial BP, but with lower averages.

Ablation of atrial fibrillation and esophageal injury: Role of bipolar and unipolar energy using a novel multipolar irrigated ablation catheter.

The circular nMARQ ablation catheter is a useful tool for pulmonary vein isolation (PVI). Some studies reported a high incidence of esophageal lesions by using this catheter. The primary aim of this study was to compare the effects on the esophageal wall of bipolar and unipolar energy applied by the nMARQ ablation catheter during AF ablation. Forty patients (mean age 53 ± 8 years; 26 [65%] men) were enrolled to perform PVI for symptomatic atrial fibrillation. Thirty patients underwent PVI with the nMARQ catheter (group 1) and 10 patients with the ThermoCool Surround Flow catheter (group 2). The procedures were performed with the CARTO3 system. All patients received an esophageal temperature probe. In group 1, we delivered unipolar energy on the left posterior wall with power between 15 and 18 W or bipolar energy with power at 15 W. In group 2, unipolar energy was delivered on the posterior atrial wall at 20-25 W power. All patients underwent esophagoscopy the day after the procedure. No patients had procedural complications. In group 1, bipolar energy was associated with a lower esophageal temperature increase as compared with unipolar energy (0.6°C [range 0-2.2°C] vs 2.1°C [range 0.8-2.9°C]; P < .001). Unipolar energy was associated with a similar temperature increase in the 2 groups (1.9°C [range 0.8-2.9°C] in group 1 vs 1.7°C [range 0.7-2.9°C] in group 2; P = .49). No patient had esophageal injury. The use of the nMARQ catheter for PVI is feasible and safe. The use of 15 W for bipolar energy or 15-18 W for unipolar energy is an optimal strategy to avoid esophageal injury with this new catheter.

Medical device postapproval safety monitoring: where does the United States stand?

A recent Food and Drug Administration (FDA) proposal aims to speed the evaluation process for new high-risk medical devices that are intended to address unmet medical needs,1 much like existing expedited approval processes, such as the humanitarian device exemption rule for devices intended to treat rare diseases. Such programs are strongly supported by the medical device industry and some patient advocacy groups, which have criticized the FDA for being too stringent in its evidentiary requirements for investigational devices, leading to delays in the approval of potentially helpful products.2–4 For example, in 2011, the FDA approved a transcatheter aortic valve replacement system that demonstrated significant improvements over conventional treatment options for selected patients with severe aortic stenosis.5,6 However, the United States was the 43rd country to approve the device, roughly 4 years after the European Union.7 Yet expedited approval for high-risk medical devices raises the possibility that these devices will not be as effective as predicted in their limited premarket testing or that they could cause unanticipated harms after approval.8 Of course, well-studied devices may present unexpected safety concerns years after approval,9,10 and even the most rigorous conventional premarket approval process will result in some devices later found to be unsafe or ineffective.11–13 Safety of approved medical devices and the proper scope of premarket testing remain contentious issues after recalls of several widely used devices, including popular models of implantable cardioverter defibrillator leads14,15 and metal-on-metal hip implants.16 Inherent limitations in premarket testing, along with the prospect of lowered evidentiary standards for expedited device reviews, place greater pressures on postapproval monitoring of devices to follow clinical performance and to identify emerging public health problems. Medical device manufacturers routinely perform this sort of vigilance, …

Abstract 12271: Radiofrequency Ablation With Electrode in Contact With Circular Mapping Catheter: Coagulation, Char, and Pop Ocurrence Comparison With Two Types of Irrigated Ablation Catheters

Introduction: A circular mapping catheter (CMC, Biosense Webster Lasso® Catheter) is frequently used in radiofrequency (RF) ablation treatment of atrial fibrillation to aid in determining ablation targets, such as the pulmonary vein ostia. During RF delivery, the ablation electrode is often in close proximity and may sometimes be in contact with one of the electrodes of the CMC. In this study, we compare coagulation, tissue char, and pop occurrence for ablations in contact with a CMC electrode versus ablations without a CMC. Ablations were performed with open-irrigation ablation electrodes of the Biosense Webster ThermoCool® Catheter (6 hole) and ThermoCool® SF Catheter (56 hole). Hypothesis: There will be more coagulation formation when there is contact with CMC. Methods: The thigh muscles of 4 anesthetized pigs were exposed and a skin cradle created. A 6 hole or 56 hole catheter was placed on the muscle with 10g of force in perpendicular orientation. Some ablations were performed with the ablation catheter alone, while others were performed with a CMC resting on the thigh muscle and the ablation electrode contacting one of the CMC electrodes on top or on the side. Heparinized autologous blood (activated clotting time &gt; 350s) at 37°C was circulated in the thigh cradle at 275-300ml/min while ablations were performed at 50W for 60s with 30ml/min irrigation for 6 hole and 15ml/min for 56 hole. Pops during ablation were noted. After the ablation, the blood pool was removed while keeping the catheters in position, the ablation site was examined, and coagulation and tissue char was noted Results: See Table Conclusions: When comparing ablations with a CMC versus no CMC, there was more coagulation with a CMC. When comparing a 6 hole catheter with a CMC versus a 56 hole catheter with a CMC, there was more coagulation with the 6 hole ablation catheter. There was no significant difference in pop and tissue char in any comparison

24Acute and long-term outcomes for patients undergoing radiofrequency catheter ablation of scar-related ventricular tachycardia by robotic catheter navigation

Introduction: Robotically-guided ablation offers theoretical advantages with greater catheter stability that can improve lesion depth. We performed a non-randomised comparison of patients undergoing ventricular tachycardia (VT) ablation either manually or using the Hansen robotic system. Methods: Consecutive patients with infarct-related scar underwent VT ablation using the Hansen system to assess feasibility, and were compared with patients undergoing manual VT ablation during the study period. All cases underwent a transeptal endocardial approach, using CARTO™ and irrigated catheter ablation guided by activation and entrainment manoeuvres if VT was sustained and tolerated, or substrate modification. The 6 month pre-ablation Implantable Cardioverter Defibrillator (ICD) therapy (Anti-tachycardia pacing (ATP) + shocks) was compared with the post ablation burden represented as a 6 monthly rate of each patient's total therapy burden during follow up ((6/follow-up duration (mths)) x total therapies post ablation)). Results: 25pts had VT ablations for infarct related scar during the study period. 13 pts had robotically guided ablation and 12 pts had manual ablation. Patients in both the robotic and manual groups had significantly impaired left ventricular function (EF 27±14% vs. 32 + /-11% respectively; p=0.32). The previous coronary revascularisationapproach, use of cardiac resynchronisation and amiodarone were similar in both groups. However 31% (4/13) of patients undergoing robotic ablation had been referred due to a failed manual approach and persisting high therapy burden as compared to 8% (1/12) redo procedures in the manual group (p=0.37). This was reflected by a trend towards higher pre-ablation therapy burden in the robotic as compared to the manual group (mean 312±566 vs. 11±9, p=0.08; median 11 vs. 9.5, p=0.50). In each group, 1 patient presented with slow incessant VT below the device therapy zone, and 1 patient had their device implanted post ablation. Post-procedure, the clinical VT was non-inducible in 85% (11/13) of the robotic group and in 92% (11/12) of the manual group. There were no peri-procedural complications. Mean follow-up was 23.5 months. Long-term mortality rates were similar (31%, 4/13 vs. 25%, 3/12; p=1.0). Post ablation, the 6 monthly therapy burden fell in both the robotic (mean reduction=290±560, median 3, p=0.047 Wilcoxon signed rank test) and manual (mean reduction=5.3±19, median 6.5, p=0.03) group. The overall reduction in therapy across all patients was 93% in the robotic and by 48% in the manual group. Conclusions: In this feasibility study, robotic VT ablation had a similar safety profile to manual ablation and a trend towards greater therapy reduction in a sicker cohort of patients. Table comparing acute procedural outcomes, 6 month pre/post ablation ICD therapies, and mortality rates between the robotic and manual groups. †Students t-test. §Fisher's exact test. ‖ Wilcoxon signed rank test. ![Graphic][1] [1]: /embed/inline-graphic-1.gif

Does diffuse irrigation result in improved radiofrequency catheter ablation? A prospective randomized study of right atrial typical flutter ablation.

Recent developments of open irrigated catheters have sought to create uniform cooling of the entire ablating electrode. The aim of this randomized study was to assess whether the diffuse irrigation of the Coolflex(®) (CF) catheter results in improved short-term procedural benefits in patients undergoing ablation of right atrial typical flutter. Sixty consecutive patients (age 62 ± 13) with typical atrial flutter were prospectively randomized to ablation of the cavotricuspid isthmus (CTI) using either a standard 3.5 mm tip ablation catheter with six distal irrigation channels (6C) (30 patients) or a 4 mm tip fully irrigated ablation catheter (CF) (30 patients). There were no significant differences seen between procedures performed with the diffusely irrigated CF catheter and the standard six-channel irrigated-tip catheter. This concerned the total procedural duration RF duration, fluoroscopic duration, the total amount of irrigation fluid, and the occurrence of steam pop. The use of a diffuse irrigation at the ablation catheter tip does neither facilitate lesion formation nor reduce the amount of irrigation during RF ablation for typical right atrial flutter using recommended flow and power settings.

Safety of radiofrequency catheter ablation without coronary angiography in aortic cusp ventricular arrhythmias.

Ventricular arrhythmias (VAs) originating from the aortic root are common. Coronary angiography is typically recommended before catheter ablation to document proximity of the ablation catheter to the coronary ostia. To investigate how often catheter ablation in the aortic root could be guided by phased-array intracardiac echocardiography (ICE) and electroanatomic mapping without requiring aortography or coronary angiography. We reviewed consecutive patients referred for aortic root VAs to operators experienced in the use of ICE at a single center. An ICE catheter and a 3.5-mm irrigated ablation catheter were used in all cases, and the need for angiography before ablation was documented. Acute success and acute and 30-day complications were noted. Thirty-five patients (age 58 ± 13 years; 74% men) were referred for the ablation of VAs; 32 of 35 (91%) underwent ablation using ICE and 3-dimensional mapping without the need for coronary angiography. Successful acute ablation was achieved in 29 of 35 (83%) patients. In all cases, the catheter tip was directly visualized with ICE >1 cm from the coronary ostia. The site of origin of the earliest VA was the left cusp (17 of 35 [49%]), right cusp (9 of 35 [26%]), right-left cusp junction (8 of 35 [23%]), or right-noncoronary cusp junction (1 of 35 [3%]). There were no cases of coronary injury, embolic stroke, aortic root perforation, worsening of aortic regurgitation, or death acutely or at 30 days. Radiofrequency ablation of VAs originating from the aortic root may be safely performed using ICE and electroanatomic mapping in the majority of cases without the need for coronary angiography.

Safety and efficacy of renal denervation as a novel treatment of ventricular tachycardia storm in patients with cardiomyopathy

Modulation of the autonomic nervous system has been used to treat refractory ventricular tachycardia (VT). Renal artery denervation (RDN) is under investigation for the treatment of sympathetic-driven cardiovascular diseases. The purpose of this study was to report the largest case series to date using RDN as adjunctive therapy for refractory VT in patients with underlying cardiomyopathy. Four patients with cardiomyopathy (2 nonischemic, 2 ischemic) with recurrent VT despite maximized antiarrhythmic therapy and prior endocardial (n = 2) or endocardial/epicardial (n = 2) ablation underwent RDN ± repeat VT ablation. RDN was performed spirally along each main renal artery with either a nonirrigated (6 W at 50°C for 60 seconds) or an open irrigated ablation catheter (10-12 W for 30-60 seconds). Renal arteriography was performed before and after RDN. RDN was well tolerated acutely and demonstrated no clinically significant complications during follow-up of 8.8 ± 2.6 months (range 5.0-11.0 months). No hemodynamic deterioration or worsening of renal function was observed. The number of VT episodes was decreased from 11.0 ± 4.2 (5.0-14.0) during the month before ablation to 0.3 ± 0.1 (0.2-0.4) per month after ablation. All VT episodes occurred in the first 4 months after ablation (2.6 ± 1.5 months). The responses to RDN were similar for ischemic and nonischemic patients. This case series provides promising preliminary data on the safety and effectiveness of RDN as an adjunctive therapy in the treatment of patients with cardiomyopathy and VT resistant to standard interventions.

Abstract 9570: Adenosine Triphosphate Facilitates Dormant Conduction across Left Atrial Lines in Patients With Atrial Fibrillation Who Underwent Catheter Ablation

Introduction: The addition of left atrial lines including a roof line, bottom line, and mitral isthmus line after pulmonary vein (PV) isolation may lead to a favorable outcome of atrial fibrillation (AF) ablation. Transient reconduction of the isolated pulmonary vein (PV) is induced by administration of adenosine triphosphate (ATP) and elimination of dormant conduction improves outcome of AF ablation. The potential role of ATP in other arrhythmic substrates, such as left atrial lines, remains unclear. The aim of this study was to investigate the characteristics and frequency of dormant left atrial line conduction. Methods: Sixty-four patients (50 men; mean age 65±10; 3 paroxysmal, 26 persistent, 35 Longstanding persistent) who underwent first ablation of left atrial lines were enrolled in this study. A roof line, bottom line and mitral isthmus line were performed in 63 patients, 44 patients and 64 patients, respectively. Irrigated ablation catheters were used through steerable sheaths with a max power of 35W at the endocardial surface and 30W in the coronary sinus. ATP (20mg) was given greater than 10 minutes after completion of left atrial lines to reveal dormant conduction. Results: Completion of a roof line, bottom line and mitral isthmus line was achieved in 97% (61/63), 98% (43/44), and 95% (61/64), respectively. Following administration of ATP, dormant conduction was observed in 3.2% at a roof line, 2.3% at a bottom line, and 3.2% at a mitral isthmus line. Persistent reconduction was observed in 1.6% at a roof line and 2.3% at a bottom line. Transient reconduction was observed in 1.6% at a roof line and 3.2% at a mitral isthmus line. Following additional ablation, dormant left atrial line conduction was eliminated in all patients. The frequency of dormant left atrial line conduction was similar to that of dormant PV conduction (6.3% vs 7.8%., P=0.7) Conclusion: Administration of ATP could reveal dormant left atrial line conduction. Dormant conduction was evenly induced among PVs and left atrial lines.

Ablation of right ventricular outflow tract tachycardia using a novel multipolar irrigated ablation catheter (nMARQ)

A 54-year-old man with a history of hypertension presented with sudden onset of palpitation, chest pain, and dizziness. Frequent runs of nonsustained broad complex tachycardia were captured on ambulance 3-lead electrocardiogram with an inferior axis, suggestive of outflow tract ventricular tachycardia (VT). VT resolved spontaneously on admission at the coronary care unit. Subsequent echocardiography revealed normal biventricular function with normal sized left and right ventricles and no significant valvular abnormality.

Enhanced efficiency of a novel porous irrigated RF ablation catheter for pulmonary vein isolation

Enhanced efficiency of a novel porous irrigated RF ablation catheter for pulmonary vein isolation

Fluid overload and re-hospitalization following catheter ablation of long standing persistent atrial fibrillation: results from randomized study using a new irrigated catheter

Introduction: Fluid overload and/or pulmonary congestion with and without hospitalization may occur following catheter ablation of long standing persistent (LSP) atrial fibrillation (AF) with open irrigated catheters. We compared the clinical outcomes of two different open irrigated ablation catheters after catheter ablation of LSP AF. Methods: 138 patients (pts) undergoing ablation for longstanding persistent AF, were randomized to ablation with a standard 3.5 open irrigated catheter (group 1, n=46) and discharged with 40 mg bid of furosemide, or ablation with a standard 3.5 open irrigated catheter (group 2, n=46) and discharged with 80 mg bid of furosemide, and ablation with a new irrigated catheter (SF= surround flow) and discharged with 40 mg bid of furosemide (group 3 n=46). At the end of the procedure all pts were given 40 mg of i.v. furosemide. Clinical data on fluid administration, pulmonary congestion, weight increase, and re-hospitalization due to fluid overload were collected and analyzed. Results: Baseline characteristic had no statistical significant difference between groups. No differences in RF time and procedural time were observed between groups. At the end of the procedures a total of 4.4±0.9 liters of fluid were given in group 1and 2 compared to 1.7±0.7 liters in group 3 (p< 0.005). The weight of the pts the day after the procedure increased by an average of 8±2 pounds in groups 1and 2 while increased of 2±0.4 pounds in group (3) (P<0,005). One hour following the procedure, one patient in group 1 had pulmonary congestion requiring re-intubation. No acute complications were observed in groups 2 and 3. Three days after discharge only 1 pts in group 3 showed 2 pounds increase in weight. However, 27 pts in group 1 and 2 (29%) still had a mean weight increase of 4±0.4 pounds and feeling of shortness of breath. Ten patients in group 1 (22%) and 5 patient (11%) in group 2 required re-hospitalization due to fluid overload, while no patient in group 3 did. Conclusion: This prospective randomized study demonstrates that the use of the "new" open irrigated SF catheter, significantly reduce weight gain and re-hospitalization due to peri-procedural fluid overload