Andre d’Avila

Importance of catheter contact force during irrigated radiofrequency ablation: evaluation in a porcine ex vivo model using a force-sensing catheter.

Effect of Ablation Electrode Contact Force.u2002Introduction: Ablation electrode–tissue contact has been shown to be an important determinant of lesion size and safety during nonirrigated ablation but little data are available during irrigated ablation. We aimed to determine the importance of contact force during irrigated‐tip ablation.

Catheter Ablation of Ventricular Epicardial Tissue A Comparison of Standard and Cooled-Tip Radiofrequency Energy

Background—Transthoracic epicardial catheter ablation is an emerging catheter ablation strategy being used clinically at increasing frequency. However, the efficacy of standard RF ablation on the epicardial surface of the heart is hindered by (1) the lack of convective cooling of the ablation electrode and (2) the varying presence of epicardial adipose tissue interposed between the ablation electrode and the target site. This experimental animal study examines the biophysical characteristics of radiofrequency (RF) ablation lesions generated by either standard or cooled-tip ablation of the ventricular epicardium. Methods and Results—Nonsurgical subxyphoid pericardial access was achieved in 10 normal goats and 7 pigs with healed myocardial infarctions. A 4-mm cooled-tip RF ablation catheter (continuous 0.9% saline circulation at 0.6 mL/s; goal temperature, 40°C; 60 seconds) was used to deliver epicardial ventricular lesions: 47 in normal tissue and 22 in infarcted tissue. Standard RF ablation lesions (n=33) using a 4-mm top catheter (goal temperature, 70°C; 60 seconds) were also placed on normal epicardial tissue. Lesions created with standard and cooled-tip RF ablation were 3.7±1.3 mm (25±16.8 W) and 6.7±1.7 mm (44.8±6.8 W) in depth, respectively. On scar tissue, lesions made with the cooled-tip catheter measured 14.6±2.7 mm in length, 11.8±2.9 mm in width, and 5.6±1.2 mm in depth (35.6±7.1 W). In areas covered by epicardial fat (3.1±1.2 mm thick), standard RF energy did not generate any appreciable lesions, but cooled-tip RF lesions were 4.1±2 mm in depth (45±4.4 W). Conclusions—Cooled-tip RF ablation can generate epicardial lesions more effectively than standard RF ablation and appears to be of particular benefit in ablating areas with overlying epicardial fat.

Balloon catheter ablation to treat paroxysmal atrial fibrillation: What is the level of pulmonary venous isolation?

BACKGROUNDnUnlike the initial balloon ablation catheters that were designed to deliver ablation lesions within the pulmonary veins (PVs), the current balloon prototypes are fashioned to deliver lesions at the PV ostia.nnnOBJECTIVEnUsing electroanatomical mapping, this study evaluates the actual location of ablation lesions generated by cryo-based, laser-based, or ultrasound-based balloon catheters.nnnMETHODSnIn a total of 14 patients with paroxysmal atrial fibrillation, PV isolation was performed using either a cryoballoon catheter (8 patients), laser catheter (4 patients) or ultrasound balloon catheter (2 patients). Patients underwent preprocedural computed tomographic/magnetic resonance imaging. An intracardiac ultrasound catheter was used to aid in positioning the balloon catheter at the PV ostium/antrum. In all patients, sinus rhythm bipolar voltage amplitude maps (using either CARTO with computed tomographic/magnetic resonance image integration or NavX mapping) were generated at baseline and after electrical PV isolation as confirmed by use of a circular mapping catheter.nnnRESULTSnElectrical isolation was achieved in 100% of the PVs. Electroanatomical mapping revealed that after ablation with any of the 3 balloon catheters, the extent of isolation included the tubular portions of each PV to the level of the PV ostia. However, the PV antral portions were left largely unablated with all 3 balloon technologies.nnnCONCLUSIONnUsing the current generation of balloon ablation catheters, electrical isolation occurs at the level of the PV ostia, but the antral regions are largely unablated.

Remote Magnetic Navigation to Guide Endocardial and Epicardial Catheter Mapping of Scar-Related Ventricular Tachycardia

Background— The present study examines the safety and feasibility of using a remote magnetic navigation system to perform endocardial and epicardial substrate-based mapping and radiofrequency ablation in patients with scar-related ventricular tachycardia (VT). Methods and Results— Using the magnetic navigation system, we performed 27 procedures on 24 consecutive patients with a history of VT related to myocardial infarction, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, or sarcoidosis. Electroanatomic mapping of the left ventricular, right ventricular, and ventricular epicardial surfaces was constructed in 24, 10, and 12 patients, respectively. Complete-chamber VT activation maps were created in 4 patients. A total of 77 VTs were inducible, of which 21 were targeted during VT with the remotely navigated radiofrequency ablation catheter alone. With a combination of entrainment and activation mapping, 17 of 21 VTs (81%) were successfully terminated in a mean of 8.4±8.2 seconds; for the remainder, irrigated radiofrequency ablation was necessary. The mean fluoroscopy times for endocardial and epicardial mapping were 27±23 seconds (range, 0 to 105 seconds) and 18±18 seconds (range, 0 to 49 seconds), respectively. In concert with a manually navigated irrigated ablation catheter, 75 of 77 VTs (97%) were ultimately ablated. Four patients underwent a second procedure for recurrent VT, 3 with the magnetic navigation system. After 1.2 procedures per patient, VT did not recur during a mean follow-up of 7±3 months (range, 2 to 12 months). Conclusions— The present study demonstrates the safety and feasibility of remote catheter navigation to perform substrate mapping of scar-related VT in a wide range of disease states with a minimal amount of fluoroscopy exposure.

Atrial tachycardia after ablation of persistent atrial fibrillation: identification of the critical isthmus with a combination of multielectrode activation mapping and targeted entrainment mapping.

Background—Atrial tachycardia (AT) that develops after ablation of atrial fibrillation often poses a more difficult clinical situation than the index arrhythmia. This study details the use of an impedance-based electroanatomic mapping system (Ensite NavX) in concert with a specialized multielectrode mapping catheter for rapid, high-density atrial mapping. In this study, this activation mapping was combined with entrainment mapping to eliminate ATs developing late after atrial fibrillation ablation. Methods and Results—All study patients developed AT after ablation for atrial fibrillation. The approach to AT ablation consisted of 4 steps: use of a 20-pole penta-array catheter to map the chamber rapidly during the rhythm of interest, analysis of the patterns of atrial activation to identify wave fronts of electric propagation, targeted entrainment at putative channels, and catheter ablation at these “isthmuses.” All ablations were performed with irrigated radiofrequency ablation catheters. Forty-one ATs were identified in 17 patients (2.4±1.6 ATs per patient). Using the multielectrode catheter in conjunction with the Ensite NavX system, we created activation maps of 33 of 41 ATs (81%) (mean cycle length, 284±71 seconds) with a mean of 365±108 points per map and an average mapping time of 8±3 minutes. Of the 33 mapped ATs, 7 terminated either spontaneously or during entrainment maneuvers. Radiofrequency energy was used to attempt ablation of 26 ATs; 25 of 26 of the ATs (96%) were terminated successfully by ablation or catheter pressure. Conclusions—This study demonstrates a strategy for rapidly defining and eliminating the scar-related ATs typically encountered after ablation of atrial fibrillation.

Pulmonary vein isolation using a visually guided laser balloon catheter: the first 200-patient multicenter clinical experience.

Background— Because of the technical difficulty with achieving pulmonary vein (PV) isolation in the treatment of patients with paroxysmal atrial fibrillation, novel catheter designs to facilitate the procedure are in development. A visually guided laser ablation (VGLA) catheter was designed to allow the operator to directly visualize target tissue for ablation and then deliver laser energy to perform point-to-point circumferential ablation. Single-center studies have demonstrated favorable safety and efficacy. We sought to determine the multicenter feasibility, efficacy, and safety of performing PV isolation using the VGLA catheter.nnMethods and Results— This study includes the first 200 paroxysmal atrial fibrillation patients treated with the VGLA catheter (33 operators, 15 centers). After transseptal puncture, the VGLA catheter was used to perform PV isolation. Electric isolation was assessed using a circular mapping catheter. Using the VGLA catheter, 98.8% (95% confidence interval, 97.8%–99.5%) of targeted PVs were isolated using a mean of 1.07 catheters per patient. Fluoroscopy and procedure times were 31±21 (mean±SD) and 200±54 minutes, respectively, and improved with operator experience. There were no instances of stroke, transient ischemic attack, atrioesophageal fistulas, or significant PV stenosis. There was a 2% incidence of cardiac tamponade and a 2.5% incidence of phrenic nerve palsy. At 12 months, the drug-free rate of freedom from atrial arrhythmias after 1 or 2 procedures was 60.2% (95% confidence interval, 52.7%–67.4%).nnConclusions— In this multicenter experience of the first 200 patients treated with the VGLA catheter, PV isolation can be achieved in virtually all patients using a single VGLA catheter with an efficacy similar to radiofrequency ablation.Background—Because of the technical difficulty with achieving pulmonary vein (PV) isolation in the treatment of patients with paroxysmal atrial fibrillation, novel catheter designs to facilitate the procedure are in development. A visually guided laser ablation (VGLA) catheter was designed to allow the operator to directly visualize target tissue for ablation and then deliver laser energy to perform point-to-point circumferential ablation. Single-center studies have demonstrated favorable safety and efficacy. We sought to determine the multicenter feasibility, efficacy, and safety of performing PV isolation using the VGLA catheter. Methods and Results—This study includes the first 200 paroxysmal atrial fibrillation patients treated with the VGLA catheter (33 operators, 15 centers). After transseptal puncture, the VGLA catheter was used to perform PV isolation. Electric isolation was assessed using a circular mapping catheter. Using the VGLA catheter, 98.8% (95% confidence interval, 97.8%–99.5%) of targeted PVs were isolated using a mean of 1.07 catheters per patient. Fluoroscopy and procedure times were 31±21 (mean±SD) and 200±54 minutes, respectively, and improved with operator experience. There were no instances of stroke, transient ischemic attack, atrioesophageal fistulas, or significant PV stenosis. There was a 2% incidence of cardiac tamponade and a 2.5% incidence of phrenic nerve palsy. At 12 months, the drug-free rate of freedom from atrial arrhythmias after 1 or 2 procedures was 60.2% (95% confidence interval, 52.7%–67.4%). Conclusions—In this multicenter experience of the first 200 patients treated with the VGLA catheter, PV isolation can be achieved in virtually all patients using a single VGLA catheter with an efficacy similar to radiofrequency ablation.

Multicenter study on acute and long-term safety and efficacy of percutaneous left atrial appendage closure using an epicardial suture snaring device

BACKGROUNDnPericardial suture ligation of the left atrial appendage (LAA) may be an alternative to endoluminal devices for stroke prevention in patients with atrial fibrillation, but multicenter safety and efficacy data in high-risk patients with contraindications to oral anticoagulation are lacking.nnnOBJECTIVEnThe purpose of this study was to report the outcomes of consecutive cases of pericardial suture ligation of the LAA in high-risk patients performed at 4 centers.nnnMETHODSnThe cohort included 41 consecutive patients who underwent LAA closure with the LARIAT system. Epicardial and transeptal access was obtained, and the epicardial snare was advanced over an endo-epicardial magnetic-tipped guidewire to close the LAA. Transesophageal echocardiography was used to confirm LAA exclusion.nnnRESULTSnMean age was 75 ± 10 years, mean CHADS2 score was 3.0 ± 1.3, and mean HAS-BLED score was 4.4 ± 1.4. These patients accumulated 24.6 person-years of follow-up. Acute LAA closure was achieved in 38 patients (93%). Transesophageal echocardiography or computerized tomographic angiography performed up to 3.3 ± 0.8 months after the procedure demonstrated LAA leakage in 24% of patients. One patient (2%) had a transient ischemic attack, and 8 (20%) developed pericardial effusions requiring pericardiocentesis. Four cases (9%) were complicated by perforation of the LAA, with 2 of these patients requiring open surgical correction.nnnCONCLUSIONnThis multicenter experience revealed that pericardial suture ligation with the LARIAT system is technically feasible and acutely efficacious. However, additional improvements are required to minimize the rate of pericardial complications. A randomized study is warranted to accurately define the long-term efficacy and safety profile of percutaneous epicardial suture ligation.

Percutaneous hemodynamic support with Impella 2.5 during scar-related ventricular tachycardia ablation (PERMIT 1).

Background—Percutaneous left ventricular assist devices (pLVADs) are increasingly being used to facilitate ablation of unstable ventricular tachycardia (VT), but the safety profile and hemodynamic benefits of these devices have not been described in a systematic, prospective manner. Methods and Results—Twenty patients with scar VT underwent ablation with a pLVAD. Neuromonitoring using cerebral oximetry was performed to evaluate a cerebral desaturation threshold to guide the duration of activation/entrainment mapping. The efficacy of pLVAD support was tested in a controlled manner with simulated VT. Complete procedural success was achieved in 50% (n=8) of patients, who were initially inducible for sustained VT, and partial procedural success in 37% (n=6). Using a cerebral desaturation level of 55% as a lower safety limit to guide the duration of sustained VT, 3 patients (15%) developed mild acute kidney injury (all resolved), and 1 (5%) patient developed mild cognitive dysfunction. During fast simulated VT (300 ms), cerebral desaturation to ⩽55% occurred in more than half (53%) of patients tested without pLVAD support, compared with only 5% with full pLVAD support (P=0.003). Conclusions—In a consecutive series of patients with severe left ventricular dysfunction, pLVAD-supported scar VT ablation was safe and feasible. During fast simulated VT, a miniaturized axial flow pump imparted a more favorable hemodynamic profile compared with pharmacological agents alone. Cerebral oximetry is a complimentary monitoring modality during scar VT ablation, and avoidance of cerebral desaturations below a threshold of 55% may safely guide the duration of mapping during unstable VT.

Factors affecting error in integration of electroanatomic mapping with CT and MR imaging during catheter ablation of atrial fibrillation

ObjectiveIntegration of 3-D electroanatomic mapping with Computed Tomographic (CT) and Magnetic Resonance (MR) imaging is gaining acceptance to facilitate catheter ablation of atrial fibrillation. This is critically dependent on accurate integration of electroanatomic maps with CT or MR images. We sought to examine the effect of patient- and technique-related factors on integration accuracy of electroanatomic mapping with CT and MR imaging of the left atrium.Materials and methodsSixty-one patients undergoing catheter-based atrial fibrillation (AF) ablation procedures were included. All patients underwent cardiac CT (nu2009=u200911) or MR (nu2009=u200950) imaging, and image integration with real-time electroanatomic mapping of the aorta and left atrium (LA). CARTO-Merge software (Biosense-Webster) was used to calculate the overall average accuracy of integration of electroanatomic points with the CT and MR-derived reconstructions of the LA and aorta.ResultsThere was a significant correlation between LA size assessed by electroanatomic mapping (112u2009±u200931xa0ml) and average integration error (1.9u2009±u20090.6xa0mm) (ru2009=u20090.46, pu2009=u20090.0003). There was also greater integration error for patients with LA volumeu2009≥u2009110xa0ml (nu2009=u200931) versusu2009<u2009110xa0ml (nu2009=u200930) (pu2009=u20090.004). In contrast, there was no significant association between average integration error and paroxysmal versus persistent AF, left ventricular ejection fraction, days from imaging to electroanatomic mapping, or images derived from CT versus MR.ConclusionsPatients with larger LA volume may be prone to greater error during integration of electroanatomic mapping with CT and MR imaging. Strategies to reduce integration error may therefore be especially useful in patients with large LA volume.

Clinical outcomes after repair of left atrial esophageal fistulas occurring after atrial fibrillation ablation procedures

BACKGROUNDnThe initial experience with left atrial esophageal fistula (LAEF) secondary to atrial fibrillation (AF) ablation procedures revealed a near-universal mortality. A comprehensive description of the principles of LAEF repair in the modern era and its resulting impact on morbidity and mortality are lacking in the literature.nnnOBJECTIVEnTo describe the presentation, surgical management, and outcomes of patients with LAEF.nnnMETHODSnA retrospective cohort analysis of 29 patients was performed, including previously unpublished cases of surgically repaired LAEF from 4 institutions (n = 6), and all published cases of surgically repaired (n = 16) or stented (n = 7) LAEF.nnnRESULTSnThe mean age was 55 ± 13 years, and 75% were men who were undergoing radiofrequency energy catheter ablation (n = 26), cryoablation (n = 1), high-intensity focused ultrasound ablation (n = 1), and surgical mini-MAZE procedure (n = 1) and presented 30 ± 12 days postablation procedure. Overall, 55% of the patients receiving an intervention for LAEF died (41% surgical repair; 100% stent). Patients who did not receive primary esophageal repair were more likely to experience postoperative complications, including mediastinitis, need for percutaneous endoscopic gastrostomy (PEG) feeds, esophageal stent, or death (P = .05). In addition, interposing tissue between the repaired esophagus and the left atrium resulted in fewer postoperative complications (P = .02).nnnCONCLUSIONSnWhile improved relative to initial reports, mortality associated with LAEF remains high after corrective intervention. Primary esophageal repair with the placement of tissue between the repaired esophagus and the left atrium may result in lower morbidity and mortality.