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Background Currently, little is known about the onset, natural progression, and management of esophageal injuries after atrial fibrillation (AF) ablation. Objectives We sought to provide a systematic review on esophageal injury after AF ablation and identify temporal relationships between various types of esophageal lesions, their progression, and clinical outcomes. Methods A comprehensive search of PubMed and Web of Science was conducted until September 21, 2017. All AF ablation patients who underwent upper gastrointestinal endoscopy within 1 week of the procedure were included. Patients with esophageal lesions were classified into 3 types by using our novel Kansas City classification: type 1: erythema; type 2a: superficial ulcers; type 2b: deep ulcers; type 3a: perforation without communication with the atria; and type 3b: perforation with atrioesophageal fistula. Results Thirty studies met our inclusion criteria. Of the 4473 patients, 3921 underwent upper gastrointestinal evaluation. The overall incidence of esophageal injuries was 15% (570). There were 206 type 1 lesions (36%), 222 type 2a lesions (39%), and 142 type 2b lesions (25%). Six of 142 type 2b lesions (4.2%) progressed further to type 3, of which, 5 were type 3a and 1 was type 3b. All type 1 and type 2a and most type 2b lesions resolved with conservative management. One type 3a and 1 type 3b lesions were fatal. Conclusion Based on our classification, all type 1 and most type 2 lesions resolved with conservative management. A small percentage (4.2% [6 of 142]) of type 2b lesions progressed to perforation and/or fistula formation, and these patients need to be followed closely.

Background Real-time radiofrequency (RF) ablation lesion assessment is a major unmet need in cardiac electrophysiology. Objective The purpose of this study was to assess whether improved temperature measurement using a novel thermocoupling (TC) technology combined with information derived from impedance change, contact force (CF) sensing, and catheter orientation allows accurate real-time prediction of ablation lesion formation. Methods RF ablation lesions were delivered in the ventricles of 15 swine using a novel externally irrigated-tip catheter containing 6 miniature TC sensors in addition to force sensing technology. Ablation duration, power, irrigation rate, impedance drop, CF, and temperature from each sensor were recorded. The catheter "orientation factor" was calculated using measurements from the different TC sensors. Information derived from all the sources was included in a mathematical model developed to predict lesion depth and validated against histologic measurements. Results A total of 143 ablation lesions were delivered to the left ventricle (n = 74) and right ventricle (n = 69). Mean CF applied during the ablations was 14.34 ± 3.55g, and mean impedance drop achieved during the ablations was 17.5 ± 6.41 Ω. Mean difference between predicted and measured ablation lesion depth was 0.72 ± 0.56 mm. In the majority of lesions (91.6%), the difference between estimated and measured depth was ≤1.5 mm. Conclusion Accurate real-time prediction of RF lesion depth is feasible using a novel ablation catheter-based system in conjunction with a mathematical prediction model, combining elaborate temperature measurements with information derived from catheter orientation, CF sensing, impedance change, and additional ablation parameters.

The study was prompted by our observation that some patients with neurally mediated syncope (NMS) have an isolated QRS complex, of very low voltage (≤0.3 mV cutoff), in 1 of the frontal leads on the 12-lead electrocardiogram.To prospectively evaluate whether the presence of isolated very low voltage (VLV) predicts recurrence of NMS.We included 205 patients (aged 50 ± 17 years) with a median of 3 syncopal episodes. Tilt testing was performed in all patients and was positive in 87 (42%). The patients were followed for a median of 14 months.VLV in frontal leads was present in 92 patients (45%). During the follow-up period 60 patients experienced recurrence of syncope. The actuarial total syncope recurrence rate at 1 year was 32% (95% confidence interval [CI 23%-44%) in patients with isolated VLV in frontal plane leads, and 14% (95% CI 8%-24%) in patients without VLV (log-rank test P.0001). The significant relationship between the presence of isolated VLV in the frontal leads and syncope recurrence was retained in Cox multivariate analysis that included the history of presyncope and syncope as well as the left ventricular end-diastolic diameter. The presence of isolated VLV in frontal leads was associated with a 3-fold increase of the risk of recurrent syncope.Isolated very low QRS voltage in the frontal leads predicts recurrence of NMS independent of clinical factors that predict recurrence of syncope in such patients. This phenomenon may help generate new diagnostic tools and insights into the pathogenesis of NMS.

Background Predictable progression to battery depletion is necessary for device management in patients with pacemakers or implantable cardioverter-defibrillators, particularly in patients who either are pacemaker dependent or have required implantable cardioverter-defibrillator therapies. Objective To determine the incidence and characteristics of unexpected battery depletion in patients implanted with a cardiac resynchronization therapy – defibrillator (CRT-D) device. Methods All patients with a St Jude Atlas+ HF or Atlas II HF CRT-D device implanted between 2004 and 2007 at the Massachusetts General Hospital and the Nashville VA Medical Center (Vanderbilt University) were studied. All patients with early generator depletion (transition of generator voltage above specified elective replacement indicator [ERI] to end of life [EOL] in less than 90 days) were evaluated further. Results Eight cases (mean age 69.6 ± 9 years) with abrupt battery depletion were identified among 191 patients (4.2%) implanted with a St Jude Atlas CRT-D device. The longevity of 8 premature depletion devices was 46.4 ± 10 months (median 45 months). The battery voltage in these 8 devices decreased from a mean of 2.48 ± 0.03 V (above ERI) to 2.3 ± 0.08 V (below ERI) over 33.3 ± 23 days (range 1–59 days; median 38.5 days). One device reached EOL status within 1 day of having battery voltage above ERI and another device within 12 days. Conclusion The incidence of abrupt battery depletion was 4.2% in patients implanted with a St Jude Atlas CRT-D device. No common mechanism has been identified for this failure. Close monitoring of battery voltage and timely generator replacement are required in patients with these devices.

The optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricle (LV) lateral or posterolateral wall. However, little is known about the impact of segmental pacing site on outcomes.We assessed the impact of segmental LV lead position on CRT outcomes.Patients (n = 115) undergoing CRT were followed prospectively. Segmental LV lead position along the longitudinal axis (apical, midventricle, or basal) was determined retrospectively by examining coronary sinus (CS) venograms and chest X-rays. The primary outcome was a combined endpoint of heart failure hospitalization, cardiac transplantation, or all-cause mortality. Secondary outcomes included change in New York Heart Association (NYHA) functional class and degree of LV reverse remodeling.Patients were divided into two groups based on LV lead position: apical (n = 25) and basal/midventricle (n = 90). The apical group was older (72.9 +/- 8.9 vs. 66.5 +/- 13.3 years; P = .010) and more likely to have ischemic cardiomyopathy (77% vs. 52%, P.001). During a mean follow-up of 15.1 +/- 9.0 months, event-free survival was significantly lower in the apical group: 52% vs. 79%, hazard ratio [HR] 2.7 (95% confidence interval [CI] 1.5-5.5, P = .006). The adverse impact of apical lead placement remained significant after adjusting for clinical covariates: HR 2.3 (95% CI 1.1-4.8, P = .03). The apical group also experienced less improvement in NYHA functional class and less LV reverse remodeling.Apical LV lead placement is associated with worse CRT outcomes. Preferential positioning of LV leads in the basal/midventricle segments may improve outcomes.

Cryoenergy is being increasingly used for atrial fibrillation (AF) ablation, but the thermal effect of cryoenergy on the esophagus remains undefined.This study examines the esophageal effects of cryoenergy used during AF ablation.Catheter ablation was performed using a cryoballoon catheter in 67 AF patients (Cryoballoon group), and a spot cryocatheter to complete irrigated radiofrequency lesion sets at segments in close proximity to the esophagus in 7 AF patients (Cryo-Focal group). A temperature probe monitored the luminal esophageal temperature (LET) in all patients; LET changes did not guide therapy. Post-procedural endoscopy was performed on 35 of 67 (52%) Cryoballoon and all Cryo-Focal patients.Significant LET decreases (1 degrees C) occurred in 62 of 67 (93%) Cryoballoon patients. LET continued to decrease after termination of cryoablation before recovering to normal. Temperature decreases were more pronounced during ablation at the inferior (3.1 degrees C) than superior pulmonary veins (1.5 degrees C); the lowest observed temperature was 0 degrees C. Post-procedural endoscopy showed esophageal ulcerations in 6 of 35 (17%) patients. There were no atrial-esophageal fistulas, and all ulcers had healed on follow-up endoscopy. Patients with and without ulceration differed with respect to mean LET nadir, cumulative LET decrease, and number of LETs30 degrees C. In the Cryo-Focal group, 6 +/- 2 spot cryolesions per patient resulted in 1.3 +/- 1 LET decreases per patient, and an absolute nadir of 32.5 degrees C.Cryoballoon ablation can cause significant LET decreases, resulting in reversible esophageal ulcerations in 17% of patients. No ulcerations occurred with adjunctive spot cryoablation at regions near the esophagus during radiofrequency ablation procedures.

Background The presence and extent of contraction within the pulmonary veins (PVs) have not been defined clearly. Objective The purpose of this study was to determine whether PV contraction exists and can be visualized using multislice computed tomography (MSCT) scanning as this may indicate that this modality may be useful for monitoring patients after PV isolation procedures. Methods Analysis was performed on 29 patients (mean age 57.5 ± 12 years) undergoing MSCT for suspected coronary artery disease without structural heart disease or left atrial anatomical variants. Multiplane reconstructions were used to measure PV diameters at 0, 5, 10, and 15 mm from the ostium in two phases (maximum and minimum size). The ejection fractions of three 5-mm segments were calculated for each PV. Results Right-sided and left-sided PV contraction and maximal atrial contraction occurred at a median of 85% and 95% of the cardiac cycle, respectively. The temporal concordance of minimal PV volume during peak atrial contraction indicated that the PV volume changes are secondary to active contraction rather than passive reflux and PV distension. The ejection fractions were highest in the superior veins: right superior PV (36.7%, 27.8%, and 16%, respectively, for the three segments from proximal to distal) and left superior PV (26.9%, 21.3%, and 12.1%), in comparison with the right inferior PV (21.1%, 6.6%, and −0.7%) and left inferior PV (15%, 9.3%, and 7.6%). Conclusion Volume changes related to active PV contraction occur extending up to 15 mm into the veins, and this effect is most pronounced in the superior veins.

Background Mutations in the sodium channel SCN5A have been implicated in many cardiac disorders, including the long QT syndrome, Brugada syndrome, conduction system disease, and dilated cardiomyopathy with atrial arrhythmias. Objective In view of the pleiotropic effects of SCN5A mutations, the purpose of this study was to examine a cohort of patients with familial atrial fibrillation (AF) for mutations in the SCN5A gene. Methods Probands with AF were enrolled in the study between June 1, 2001 and February 10, 2004. Each patient underwent a standardized evaluation, which included an interview, physical examination, ECG, echocardiogram, and blood sample for genetic analysis. Direct sequencing of the coding region of SCN5A was used to screen for mutations in genomic DNA. Results One hundred eighty-nine patients with AF were enrolled during the study period. From this cohort, a subset of 57 probands with a family history of AF in at least one first-degree relative was studied. Forty-seven subjects were men (82%); 45 had paroxysmal AF (79%). Echocardiography revealed ejection fraction 62% ± 6.4 % and left atrial dimension 40 ± 6.9 mm. A single mutation (N1986K) was observed in one family but was not present in more than 600 control chromosomes. Expression of the N1986K mutant in Xenopus oocytes revealed a hyperpolarizing shift in channel steady-state inactivation. Conclusion In a cohort with familial AF, a single SCN5A mutation causing the arrhythmia in one kindred was identified. These data extend the range of phenotypes observed with SCN5A mutations and suggest that variation in the SCN5A gene is not a major cause of familial AF.

Imaging the coronary venous (CV) tree to delineate the coronary sinus and its tributaries can facilitate electrophysiological procedures, such as cardiac resynchronization therapy (CRT) and catheter ablation. Venography also allows visualization of the left atrial (LA) veins, which may be a potential conduit for ablative or pacing strategies given their proximity to foci that can trigger atrial fibrillation.The aim of this study was to provide a detailed description of CV anatomy using rotational venography in patients undergoing CRT.Coronary sinus (CS) size and the presence, size, and angulation of its tributaries were determined from the analysis of rotational CV angiograms from 51 patients (age 68 +/- 11 years; n = 12 women) undergoing CRT.The CS, posterior veins, and lateral veins were identified in 100%, 76%, and 91% of patients. Lateral veins were less prevalent in patients with a history of lateral myocardial infarction than in patients without such a history (33% vs. 96%; P = .014). The diameters of the CS and its tributaries were fairly variable (7.3-18.9 mm for CS, 1.3-10.5 mm for CS tributaries). The CS was larger in men than in women and in cases of ischemic than in cases of nonischemic cardiomyopathy (all P.05). The vein of Marshall, the most constant LA vein, was identified in 37 patients; its diameter is 1.7 +/- 0.5 mm, and its takeoff angle is 154 degrees +/- 15 degrees , making the vein potentially accessible for cannulation.Differences in CV anatomy that are related to either gender or coronary artery disease could have important practical implications during the left ventricular lead implantation. The anatomical features of the vein of Marshall make it a feasible potential conduit for epicardial LA pacing.

Intracardiac electrograms can be used to guide left ventricular (LV) lead placement during implantation of cardiac resynchronization therapy (CRT) devices. Although attempts often are made to ensure that the LV lead is positioned at a site of maximal electrical delay, information on whether this is useful in predicting the acute hemodynamic response and long-term clinical outcome to CRT is limited.The purpose of this study was to assess the ability of intracardiac (electrogram) measurements made during LV lead placement in patients undergoing CRT for predicting acute hemodynamic response and long-term clinical outcome to CRT.Seventy-one subjects with standard indications for CRT underwent electrogram measurements and echocardiograms performed in the acute phase of this study. The LV lead electrical delay was measured intraoperatively from the onset of the surface ECG QRS complex to the onset of the sensed electrogram on the LV lead, as a percentage of the baseline QRS interval. Echocardiographic assessment of the hemodynamic response to CRT was measured as an intra-individual percentage change in dP/dt over baseline (DeltadP/dt, derived from the mitral regurgitation Doppler profile) with CRT on and off. dP/dt was measurable in 48 subjects, and acute responders to CRT were defined as those with DeltadP/dtor=25%. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to the primary endpoint was estimated by the Kaplan-Meier method, with comparisons made using the log rank test.LV lead electrical delay correlated weakly with DeltadP/dt of the combined group (n = 48, r = 0.311, P = .029) but was strongly correlated with DeltadP/dt in the nonischemic subgroup (n = 20, r = 0.48, P = .027). LV lead electrical delay (%) was significantly longer in acute responders (69.6 +/- 23.9 vs 31.95 +/- 11.57, P = .002) among patients with nonischemic cardiomyopathy. A reduced LV lead electrical delay (50% of the QRS duration) was associated with worse clinical outcome within the entire cohort (hazard ratio: 2.7, 95% confidence interval: 1.17-6.68, P = .032) as well as when stratified into ischemic and nonischemic subgroups.Measuring LV lead electrical delay is useful during CRT device implantation because it may help predict hemodynamic response and long-term clinical outcome.

Background Image-guided intervention using pre-acquired CT/MR 3-dimensional images is an emerging strategy for atrial fibrillation (AF) ablation but may be limited by its use of static images to depict dynamic physiology. The effect of biologic factors such as respiration on the left atrial-pulmonary venous (LA-PV) anatomy is not well understood but is likely to have important implications. Conventional CT/MR imaging is performed during an inspiratory breath-hold, while electroanatomical mapping (EAM) during "quiet" breathing approximates an expiratory breath-hold. This study examined the effects of respiration on LA-PV anatomy and the error introduced by respiration on the integration of EAM with 3D MR imaging. Methods Pre-procedural MRI angiography was performed at both end-expiration (EXP) and end -inspiration (INSP) in 20 patients undergoing AF catheter ablation. 3D INSP and EXP surface reconstructions of the LA-PVs were compared. In selected pts, EAM data acquired during the ablation procedure (n=7) were integrated with the 3D MRI datasets. Results Qualitative assessment of the INSP and EXP 3D images revealed splaying of the PVs and reduction in PV caliber of the right-sided PVs during held inspiration. After aligning these two datasets, the average surface-to-surface distance calculated by region ranged from 1.99mm (right middle PV) to 3.79mm (left superior PV). Registration of the EAM to the MRI models was better for the EXP dataset (2.30±0.73mm) than the INSP dataset (3.03±0.57mm; p=0.004). Conclusion There are significant changes in LA-PV anatomy with respiration. MR images acquired during standard held inspiration may introduce unnecessary errors in registration during image-guided intervention.

Cardiac resynchronization therapy (CRT) nonresponders have poor outcomes. The significance of progressive ventricular dysfunction among nonresponders remains unclear.We sought to define predictors of and clinical outcomes associated with progressive ventricular dysfunction despite CRT.We conducted an analysis of 328 patients undergoing CRT with defibrillator for standard indications. On the basis of 6-month echocardiograms, we classified patients as responders (those with a ≥5% increase in ejection fraction) and progressors (those with a ≥5% decrease in ejection fraction), and all others were defined as nonprogressors. Coprimary end points were 3-year (1) heart failure, left ventricular assist device (LVAD), transplantation, or death and (2) ventricular tachycardia (VT) or ventricular fibrillation (VF).Multivariable predictors of progressive ventricular dysfunction were aldosterone antagonist use (hazard ratio [HR] 0.23; P = .008), prior valve surgery (HR 3.3; P = .005), and QRS duration (HR 0.98; P = .02). More favorable changes in ventricular function were associated with lower incidences of heart failure, LVAD, transplantation, or death (70% vs 54% vs 33%; P.0001) and VT or VF (66% vs 38% vs 28%; P = .001) for progressors, nonprogressors, and responders, respectively. After multivariable adjustment, progressors remained at increased risk of heart failure, LVAD, transplantation, or death (HR 2.14; P = .0029) and VT or VF (HR 2.03; P = .046) as compared with nonprogressors. Responders were at decreased risk of heart failure, LVAD, transplantation, or death (HR 0.44; P.0001) and VT or VF (0.51; P = .015) as compared with nonprogressors.Patients with progressive deterioration in ventricular function despite CRT represent a high-risk group of nonresponders at increased risk of worsened clinical outcomes.

w s d i a o s t h t m p The utilization of computed tomography (CT) and magetic resonance imaging (MRI) in the electrophysiology aboratory is increasing steadily. Current clinical use of hese images consists of preprocedural planning of catheter blation procedures for treatment of ventricular tachycardia nd atrial fibrillation utilizing three-dimensional reconstrucions to provide the geometry and sizes of cardiac structures. he reconstructions are integrated with electroanatomic sysems to provide anatomically accurate road maps to guide atheter manipulation. A future phase may use postproceural CT or MRI to assess the long-term success of an blation procedure through quantification of the size and ocation of the ablation lesions and possibly through quanification of changes in cardiovascular function resulting rom the procedure. A yet longer-term phase may involve sing MRI or CT imaging during the ablation process, roviding feedback to the clinician on the locations and uality of the lesions created in real time. The study by ickfeld et al in the current issue of Heart Rhythm is ntended to enable the utilization of MRI for follow-up. The tudy also provides valuable data that would be necessary or proper utilization of intraprocedural MRI. Characterizing radiofrequency (RF) lesions with nonconrast-enhanced MRI is an important goal. Use of gadolinium Gd)-DTPA contrast-enhanced MRI, despite its higher inerent contrast-to-noise ratio, is less desirable for a number f reasons. First, the use of contrast does not allow repeated racking of lesion growth during the delivery of RF current ecause an extended period ( 40–60 minutes) is required etween contrast administrations to allow for kidney clearnce. Second, differentiation of acute from chronic lesions e.g., fibrosis) is difficult with most contrast-enhanced MRI echniques. Third, there are limits to contrast dosages. Fially, there is concern about the possible consequences of d-DTPA not being cleared for lengthy periods from poorly erfused lesion regions, which may lead to ionic Gd, which s toxic, remaining within the body.

Background The delivery of radiofrequency (RF) energy to the posterior left atrium creates a risk of injury to the adjacent esophagus. Esophageal endoscopy (EGD) is used to screen patients at risk for esophageal thermal injury after RF ablation. Objective The purpose of this study was to analyze the macroscopic features of the severity of esophageal injuries induced by RF ablation to the left atrium as seen by EGD and evaluate the association of these descriptions with the time elapsed until complete healing. Methods This study analyzed 219 patients undergoing RF ablation for atrial fibrillation. Esophageal temperature probes were used during each ablation, and EGD was performed in cases with intraesophageal temperature ≥39°C. Repeat EGD was obtained at 10 days to evaluate for healing in all cases demonstrating esophageal injury. Serial endoscopies were repeated every 2 weeks until complete healing was documented. Lesions were classified according to severity as superficial or deep ulceration; size and shape were also noted. Results We found 37.4% of patients (82 of 219) with esophageal intraluminal temperatures ≥39°C. Of these, 22 patients (27%) were identified with esophageal injury, with 68% being superficial ulcerations and 32% deep. On repeat EGD at 10 days, only 29% of deep ulcerations were healed, as compared with 87% of the superficial injuries (P = .0136). No difference in healing was found when analyzed for size or shape. Conclusions The macroscopic severity of esophageal lesions detected on endoscopy the day after RF ablation can predict the time to resolution, with severe, deep ulcerations requiring a longer time to heal.

Background Pulmonary vein isolation (PVI) achieved using a cryoballoon has been shown to be safe and effective. This treatment modality has limited effectiveness for treatment of persistent atrial fibrillation (AF). Objective The purpose of this study was to evaluate a combined approach using a cryoballoon for treatment of PVI and focal radiofrequency (RF) left atrial substrate ablation for treatment of persistent AF. Methods Twenty-two consecutive patients with persistent AF were included in the study. PVI initially was performed with a cryoballoon. Left atrial complex fractionated atrial electrograms (CFAEs) then were ablated using an RF catheter. Finally, linear ablations using the RF catheter were performed. Results Eighty-three PVs, including five with left common ostia, were targeted and isolated (100%). Seventy-seven (94%) of 82 PVs targeted with the cryoballoon were isolated, and 5 (6%) required use of RF energy to complete isolation. A mean of 9.7 ± 2.6 cryoablation applications per patient was needed to achieve PVI. Median time required for cryoablation per vein was 600 seconds, and mean number of balloon applications per vein was 2.5 ± 1.0. In 19 (86%) patients in whom AF persisted after PVI, CFAE areas were ablated using the RF catheter. Two cases of transient phrenic nerve paralysis occurred. After a single procedure and mean follow-up of 6.0 ± 2.9 months, 86.4% of patients were AF-free without antiarrhythmic drugs. Conclusion A combined approach of cryoablation and RF ablation for treatment of persistent AF is feasible and is associated with a favorable short-term outcome.

Background Three-dimensional (3D) reconstruction of the left atrium (LA) can be performed using real-time intracardiac echocardiography (ICE) to facilitate image integration during atrial fibrillation (AF) ablation. Current users of this technology generally image the LA indirectly from the right atrium (RA). Objective The purpose of this study was to assess the feasibility and accuracy of image integration with placement of the ICE catheter directly in the LA to visualize the LA. Methods Thirty consecutive patients undergoing an AF ablation with the CARTO-Sound system were enrolled. A 10-Fr phased-array ICE catheter was used to obtain two-dimensional echocardiographic images of the LA; in 15 patients the ICE probe was placed in the LA, and in 15 patients it was placed only in the RA. Sequential images were obtained and merged with a preacquired computed tomography/magnetic resonance image. The accuracy of image integration was assessed by the value of the average image integration error after surface registration. Results Thirty patients (60% paroxysmal AF, LA size=42 ± 7 mm, ejection fraction=62% ± 10%) were studied. There was no difference in the time required to create the LA anatomic map and perform image integration with imaging from the LA versus the RA (22 ± 22 vs. 24 ± 16 minutes; P = .8). The number of ultrasound contours obtained was also similar (LA = 26 ± 17 vs. RA=24 ± 16; P = .7). The average integration error was less with direct LA imaging (LA = 1.83 ± 0.32 vs. RA=2.52 ± 0.58 mm; P = .0004). Conclusion Direct LA imaging with ICE is feasible and results in improved LA visualization and image integration.

Background A novel catheter design (HD Mesh ablator, Bard) combining high-density circumferential mapping and direct radiofrequency (RF) energy delivery has been developed to map and isolate the pulmonary veins (PVs). Objective The purpose of this study was to assess the feasibility of the Mesh catheter for PV isolation in patients with paroxysmal atrial fibrillation (AF). Methods Twenty consecutive patients (mean age 56.4 ± 12.2 years; 16 men) with paroxysmal drug-refractory AF were referred for ablation. The procedure was performed in a stepwise manner: PV isolation was initially attempted with the Mesh ablator, and if that was not successful, a conventional ablation approach was then used. Results A total of 73 PVs including seven veins with left common ostium were targeted. Successful deployment of the Mesh was achieved in all but four veins (94.5%). Using the Mesh catheter for ablation, PV isolation was achieved in 46 (63%) of the 73 PVs. The mean (RF) ablation time required to achieve complete isolation was 12.4 ± 6.1 minutes per PV. The Mesh-only approach allowed isolation of all veins in eight (40%) patients. In combination with conventional ablation, successful PV isolation was achieved in 71 (97%) of 73 PVs. No complications attributable to the Mesh ablator occurred in this series. Conclusions PV isolation using the Mesh catheter is feasible and may simplify the current PV isolation procedures. With the current catheter design, PV isolation could be achieved in 63% of PVs. A larger Mesh diameter with an over-the-wire design may help improve the acute success rate.

Background Recent studies have reported a possible increased risk of delayed perforation with the St. Jude Riata defibrillator lead. Objective The purpose of this study was to determine the incidence and time of occurrence of this complication in a large number of patients who underwent implantationm at a single center. Methods We reviewed the data and clinical course on all patients who underwent implantation of the St. Jude Riata (1580/1581, 1590/1591, and the 7000/7001 ST series) right ventricular defibrillator lead at the Massachusetts General Hospital between June 2001 and October 2007. Data were compared with all Medtronic Sprint Fidelis leads implanted during the same time period. Results Of a total of 416 implanted Riata leads, follow-up data at 6 weeks and 3 months was available for 87% and 75% of patients, respectively. There were 6 cases of lead perforation (6 of 233, 2.6%) with the 1580/1581 series, no cases of lead perforation (0 of 92) with the 1590/1591 series, and 2 cases of perforation (2 of 92, 2.2%) with the 7000/7001 ST series. Interrogation the day after implantation did not reveal any abnormalities. Patients with perforation developed symptoms of chest pain or shortness of breath within 3 weeks post-implantation; interrogation revealed pacing thresholds of >5 V at 0.5 ms within the first follow-up period of 6 weeks. Conclusion All cases of perforation with the St. Jude Riata lead occurred within 6 weeks post-implantation and showed pacing thresholds >5 V at 0.5 ms. There were no cases of delayed perforation after 6 weeks in 307 patients with at least 3 months of follow-up.

Background Unlike 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. Objective Using electroanatomical mapping, this study evaluates the actual location of ablation lesions generated by cryo-based, laser-based, or ultrasound-based balloon catheters. Methods In 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. Results Electrical 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. Conclusion Using the current generation of balloon ablation catheters, electrical isolation occurs at the level of the PV ostia, but the antral regions are largely unablated.

Background Over 90% of thrombi in atrial fibrillation (AF) originate from the left atrial appendage (LAA). Patients with contraindications to anticoagulation are potential candidates for LAA occlusion using the Percutaneous Left Atrial Appendage Transcatheter Occlusion system (PLAATO, ev3 Inc., Plymouth, MN). Transesophageal echocardiography (TEE) is typically used to guide implantation. Objective This study sought to examine the utility of intracardiac echocardiography (ICE) in providing adequate imaging guidance as an alternative to TEE during PLAATO implantation. Methods The study group consisted of 10 patients who underwent PLAATO implantation with simultaneous TEE and ICE imaging guidance. ICE was used to perform the following tasks typically fulfilled by TEE: (1) verification of the absence of LAA thrombus, (2) identification of the LAA ostial dimension for device sizing, (3) guidance of transseptal puncture, (4) verification of the delivery sheath position, and (5) confirmation of location and stability of device before its irrecoverable release. The ability of ICE to perform these tasks was assessed from three separate positions: the standard right atrial (RA) position, within the coronary sinus (CS), and the right ventricular outflow tract. Results ICE imaging of the LAA was optimal from within the CS, although imaging from the proximal pulmonary artery provided better visualization of the distal LAA in cross-section. The LAA dimensions, confirmation of the absence of LAA thrombus, proper positioning of the delivery sheath, verification of location and stability of the device obtained by ICE were consistent with findings from TEE. Conclusion Using nonconventional imaging planes, ICE imaging was able to perform the intraprocedural functions provided by TEE during implantation of the PLAATO left atrial appendage occlusion device.

Background Recent interest has focused on the left atrial appendage (LAA) in the setting of atrial fibrillation as a potential source of thromboembolism and stroke, which may be amenable to permanent occlusion by a variety of investigational catheter-delivered devices. Precise anatomic characterization of the LAA is necessary to determine the suitability of a patient for device placement and for device selection and sizing. Objectives The purpose of this study was to perform detailed three-dimensional characterization of LAA size and geometry by magnetic resonance angiography. Methods Fifty patients with chronic atrial fibrillation undergoing cardiac magnetic resonance angiography in preparation for catheter ablation of atrial fibrillation were analyzed for LAA volume, neck size, depth, and overall geometry. Results The average LAA volume was 17.3 ± 6.7 mL, with a depth of 26.6 ± 4.9 mm and a "neck" diameter of 20.0 ± 5.3 mm × 14.1 ± 4.7 mm. The average number of LAA lobes was 1.4 ± 0.7 (range 1–4). Substantial interpatient variability was present in the relative dimensions and morphology of the LAA. There was a significant correlation between left atrial size and LAA neck dimensions. Conclusion There is significant heterogeneity in LAA size and dimensions among patients with atrial fibrillation. Device occlusion of the LAA may require devices that are available in multiple sizes/shapes or that can adapt to this heterogeneity.

Background With the increasing use of implantable cardioverter-defibrillators (ICDs), device complications are becoming more common. Fungal-related ICD infections have rarely been reported, and little is known about the presentation, prevalence, and treatment options for these morbid infections. Objectives The purpose of this study was to characterize the clinical features, treatment, and outcomes of patients with fungal ICD infections. Methods We performed a retrospective review of ICD procedures performed at a single academic center and identified all ICD-related infections managed between 1983 and 2005. Results Among a total of 3,648 ICD-related procedures performed between 1983 and 2005, we identified 47 (1.3%) cases of ICD infections, of which 5 (0.1%) were due to a fungal pathogen. Fungal infections were more likely to be associated with abdominal devices, to have a local rather than systemic infection, and to have a longer duration from the original implant to presentation. All patients were treated with ICD system explantation and antifungal therapy. Conclusion Fungal infection of ICDs is a rare but serious complication of device implantation that must be treated aggressively with complete hardware explantation and prolonged antifungal therapy. Because most infections are late complications and have indolent onsets, a high level of clinical suspicion is required for early diagnosis.

Background A potential complication during ablation of atrial fibrillation (AF) is damage to adjacent structures such as the esophagus and aorta. Fatal atrio-esophageal fistulas have developed after surgery- or catheter-based AF ablation procedures. Objectives The purpose of this study was to analyze multidetector computed tomography (MDCT) angiographic images to determine the anatomic relationship of the aorta and esophagus to the left atrium (LA). Methods Sixty-five subjects underwent CT imaging using a 16-slice MDCT scanner: 24 with paroxysmal AF, 21 with chronic AF, and 20 "control" subjects without a history of AF. Measurements assessed included LA diameters, width of the esophagus and aorta in contact with the posterior LA wall, and distance from the esophagus to the four pulmonary veins (PVs), spine, and LA endocardium. Results Mean LA diameters were significantly larger in patients with AF vs the control group ( P = .003 for anteroposterior diameter; P = .009 for transverse diameter). The anterior aspect of the esophagus was directly apposed to the LA in all cases (contact width 18.9 ± 4.4 mm). The position of the esophagus varied in the posterior mediastinum but on average was closer to the ostia of the left PVs ( P = .0001). The descending aorta was in contact with the LA and/or left PVs in 50 of 65 subjects. The esophagus was closer to the spine in the chronic AF vs control group ( P = .007), likely due to increased LA dimension. Conclusion In addition to its ability to assess PV anatomy, preprocedural MDCT imaging can investigate the variable relationship of adjacent structures, such as the esophagus and aorta to the LA and PVs.

Use of drugs with the potential for prolongation of the QTc interval and proarrhythmia is a growing challenge facing clinicians. Many pharmaceutical agents have been denied approval for human use, approved with restrictions and warnings regarding proarrhythmia, or withdrawn from the market based upon arrhythmic risk. Despite known risk factors for QTc prolongation and drug-induced arrhythmia, precise prediction of the risk of torsades de pointes (TdP) in an individual patient remains difficult. The mechanism of drug-induced TdP typically involves use of an agent that blocks the I Kr cardiac potassium current, often in combination with risk-amplifying factors such as high drug levels, reduced drug metabolism, polypharmacy, and patient-specific factors such as gender, age, and genetic polymorphism. For the clinician, an integrated approach involving appreciation of the risk factors for proarrhythmia combined with computer-based risk assessment is the best method for reducing the risk of drug-induced proarrhythmia in clinical practice.

A 48-year-old man with a history of ischemic cardiomyopathy and coronary artery bypass surgery (left ventricular ejection fraction 15%), New York Heart Association class III congestive heart failure, and a left bundle branch block (QRS duration 146 ms) was scheduled for elective placement of cardiac resynchronization therapy (CRT) combined with a defibrillator. He had been completely free of angina since bypass surgery, and he had no history of arterial or venous spasm. The right atrial pacing lead and right ventricular pacing/defibrillator lead were placed via the left cephalic vein, and a guiding catheter (Guidant/Boston Scientific Corp.) was placed via a left subclavian puncture and manipulated easily into the coronary sinus (CS). Contrast CS venography performed in the left anterior oblique view (LAO) with a balloon-tipped occlusion catheter revealed a widely patent CS with favorable branches for left ventricular (LV) lead placement supplying the lateral LV (Figure 1A).

c a t t o t p a i l s a A r t W I p Real-time intracardiac echocardiographic (ICE) imaging is ncreasingly being used to guide catheter ablation procedures or atrial fibrillation. Using an ICE catheter placed within the ight atrium enables visualization of most of the left atrial natomy. However, visualization of the cavity of the left atrial ppendage (LAA) can difficult and, even when possible, typcally reveals only the ostium of the LAA. In patients underoing catheter ablation of atrial fibrillation, nonconventional maging planes were used to visualize the LAA by ICE imagng. Using a 10Fr phased-array ultrasound catheter (AcuNav, cuson Inc., Mountain View, CA, USA), a long-axis view of he LAA can be obtained by placing the catheter within the