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A 1.5-year-old, female-spayed mix breed dog was presented with recurrent episodes of shaking and excessive panting attributed to drug-refractory ventricular arrhythmia (VA) characterized predominantly by incessant periods of ventricular bigeminy. The VA had a narrow QRS morphology, suggestive of an origin near the His-bundle or fascicular system. Diagnostic evaluation found no structural heart disease or underlying etiology. Three-dimensional electroanatomic mapping and radiofrequency catheter ablation were pursued. Voltage mapping demonstrated normal bi-ventricular voltage (≥1.5 mV) without any fractionated or multi-component electrograms, indicating absence of ventricular myocardial scar. Pace mapping identified an endocardial origin of the VA at the basal anterior-septum of the left ventricle, distal to the His-bundle and near the left bundle branch. Two ablation lesions were delivered to this site, and a left bundle branch block was temporarily induced. The dog recovered uneventfully. One month later, the owners reported a remarkable improvement in clinical signs and follow up 48-hour Holter monitor found complete resolution of VA.

Background The right and left pulmonary artery branches (RPA, LPA) overlie inaccessible left atrial (LA) epicardium, containing the Bachmann bundle (BB), that participate in arrhythmia pathogenesis and offer an opportunity for natural surface epicardial mapping (NSEM). Objective We sought to assess the feasibility of NSEM of BB and LA roof arrhythmias. Methods Electrogram recording, pacing, and ablation was performed in 2 swine. Subsequently, NSEM and pacing from the RPA and LPA was performed in 11 consecutive patients undergoing ablation of atrial fibrillation or flutter. Pacing entrainment and ablation of LA epicardium, from the pulmonary artery (PA), was performed in cases of atypical flutter. Results Swine specimens revealed no vascular disruption and LA epicardial lesions up to 7 mm in diameter and 3 mm in depth. In clinical cases, RPA mapping was performed in 11 (100%) and LPA mapping in 6 (55%) patients. Simultaneous leftward activation of the BB followed by rightward activation of the opposing LA endocardium was recorded during crista pacing. Right and left PA median signal amplitudes were 0.71 mV and 0.30 mV, respectively. Endocardial LA median distance was 9 mm to the RPA and 15.6 mm to the LPA and LA capture was successful in 7 of 8 (88%). In cases of atypical flutter, entrainment was successful in 3 of 3 (100%) and ablation was performed. Conclusion PA NSEM can enable safe recording and entrainment of the BB, providing otherwise inaccessible epicaridal arrhythmia measurements. The safety and efficacy of ablation from the PA requires further study.

Objectives The goal of this study was to characterize the relationship between DF, the electroanatomic mapping (EAM) substrate, and outcomes of catheter ablation of VT in NICM. Background A substantial proportion of patients with nonischemic dilated cardiomyopathy (NICM) and ventricular tachycardia (VT) do not have scar detectable by cardiac magnetic resonance late gadolinium enhancement (LGE) imaging. In these patients, the significance of diffuse fibrosis (DF) detected with T1 mapping has not been previously investigated. Methods This study included 51 patients with NICM and VT undergoing catheter ablation (median age 55 years; 77% male subjects) who had no evidence of LGE on pre-procedural cardiac magnetic resonance. Post-contrast T1 relaxation time determined on the septum was assessed as a surrogate of DF burden. The extent of endocardial low-voltage areas (LVAs) at EAM was correlated with T1 mapping data. Results Bipolar LVAs were present in 22 (43%) patients (median extent 15 cm2 [8 to 29 cm2]) and unipolar LVA in all patients (median extent 48 cm2 [26 to 120 cm2]). A significant inverse correlation was found between T1 values and both unipolar-LVA (R2 = 0.64; β = –0.85; p Conclusions In patients with NICM and no evidence of LGE undergoing catheter ablation of VT, DF estimated by using post-contrast T1 mapping correlates with the voltage abnormality at EAM and seems to affect post-ablation outcomes.

Aims The aim of this study is to evaluate the incidence, predictors, and outcomes of balloon-related thrombosis (BRT) in patients undergoing transvenous lead extraction (TLE). Use of an endovascular occlusion balloon has improved outcomes of superior vena cava injuries during TLE. Its thrombogenicity in clinical practice is unknown. Methods and results We prospectively evaluated consecutive patients undergoing prophylactic balloon placement during TLE utilizing two procedural workflows: one with the balloon within the inferior vena cava during the entire case (standard cohort) and one limiting the balloon’s dwell time (abbreviated cohort). Intracardiac echocardiography was used to evaluate for significant BRT (thrombus > 1 cm) after TLE. Forty-two patients (21 in each group) were included. Age, left ventricular ejection fraction, procedural indication, number of leads, and lead dwell time were similar between the groups. Balloon dwell time was significantly longer in the standard group (128 ± 74 vs. 25 ± 18 min, P < 0.001) as was BRT (14/21 vs. 1/21, P < 0.001). Mean thrombus length and width in the standard group was 3.99 ± 1.40 and 0.45 ± 0.16 cm, respectively and 5.2 × 0.4 cm in one patient in the abbreviated group. Between patients with and without BRT in the standard group, balloon dwell times were similar (113 ± 64 vs. 156 ± 88 min, P = 0.21). One patient in the standard group had a pulmonary embolism on post-operative Day 3 and was initiated on oral anticoagulation. Conclusion Prophylactic balloon placement for the entirety of the case is associated with a high incidence of BRT; a finding that is decreased when an abbreviated workflow is utilized.

Severe endoscopically detected esophageal thermal lesions (EDELs) have been associated with higher risk of progression to atrio-esophageal fistula (AEF) following radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). We sought to evaluate safety and feasibility of active esophageal cooling using the Attune Medical Esophageal Heat Transfer Device (EnsoETM) to limit frequency or severity of EDELs. We sought To evaluate safety and feasibility of active esophageal cooling using the Attune Medical Esophageal Heat Transfer Device (EnsoETM) to limit frequency or severity of EDELs Consecutive patients undergoing first-time RFCA were randomized in a 1:1 fashion to esophageal cooling (device group) or standard temperature monitoring (control group). Ablation on the posterior wall was performed with a maximum power of 30W for up to 20s. All patients underwent EGD within 48 h. Endoscopy findings were classified as 1, erythema–mild injury; 2, superficial ulceration–moderate injury; 3, deep ulceration–significant injury; and 4, fistula/perforation. Severe EDELs were defined as grade 3 or 4 lesions. Forty-four patients completed the study (22 device group, 22 control group). Adjunctive posterior wall isolation was performed more frequently in the device group (11/22, 50% vs. 4/22, 18%). EDELs were detected in 5/22 (23%) control group patients, with mild or moderate injury in 2/5 patients (40%) and severe thermal injury in 3/5 patients (60%). In the device group, EDELs were detected in 8/22 (36%) patients, with mild or moderate injury in 7/8 (87%) patients and severe thermal injury in 1/8 (12%) patients. There was no acute perforation or AEF during follow-up. Active esophageal cooling may reduce the occurrence of severe EDELs. A larger randomized study is warranted to further evaluate the benefit of this strategy.

Background Right bundle branch block (RBBB) ventricular tachycardia (VT) morphology is a criterion for left ventricular (LV) involvement in arrhythmogenic right ventricular cardiomyopathy (ARVC). Objective The purpose of this study was to determine the frequency and chamber of origin of RBBB VT in patients with ARVC and VT. Methods We studied 110 consecutive patients with VT who met the diagnostic International Task Force criteria for ARVC and underwent VT mapping/ablation. Patients with ≥1 RBBB VT were identified. Right ventricular (RV) origin of the RBBB VT was determined based on standard mapping criteria and elimination with ablation. Results Nineteen patients (17%) had 26 RBBB VTs. Eleven of these 19 patients (58%) had 16 RBBB VTs from the RV, and 9 patients (47%) had 10 RBBB VTs originating from the LV, with 1 patient demonstrating both. RBBB VT from RV most commonly (13/16 RBBB VTs) had an early precordial QRS transition (V2 or V3), with superiorly and typically leftward directed frontal plane axis, consistent with exit from dilated RV adjacent to inferior LV septum, whereas all 10 VTs from LV had RBBB morphology with positive R waves to V5 or V6 and rightward axis in 6 VTs characteristic of basal lateral origin. Conclusion In patients with ARVC and VT presenting for VT ablation, RBBB VT occurs in 17% of cases, with most RBBB VTs (62%) originating from the RV and not indicative of LV origin. Precordial R-wave transition and frontal plane axis can be used to identify the anticipated chamber of origin of RBBB VT.

Objectives This study investigated the impact of the type of catheter irrigant used during delivery of radiofrequency ablation. Background The use of half-normal saline (HNS) as an irrigant has been suggested as a method for increasing ablation lesion size but has not been rigorously studied in the beating heart or the use of a low-flow irrigation catheter. Methods Sixteen swine underwent left ventricular mapping and ablation using either normal saline (NS) (group 1: n = 9) or half-normal saline (HNS) (group 2: n = 7). All lesions were delivered using identical parameters (40 W with 10-second ramp, 30-second duration, 15 ml/min flow, and 8- to14-g target contact force). An occurrence of steam pop, catheter char, or thrombus was assessed using intracardiac echocardiography and catheter inspection following each application. Lesion depth, width, and area were measured using electronic calibers. Results A total of 109 lesions were delivered in group 1 and 77 in group 2. There were significantly more steam pops in group 2 (32 of 77 [42%] vs. 24 of 109 [22%], respectively). The frequencies of catheter tip char were similar (group 1: 9 of 109 [8%] vs. group 2: 10 of 77 [13%]; p = 0.29). Lesion depths, widths, and areas also were similar in both groups. Conclusions The use of an HNS irrigant using a low-flow open irrigated ablation catheter platform results in more tissue heating due to higher radiofrequency current delivery directed to tissue, but this can lead to higher rate of steam pops. In this in vivo porcine beating-heart model, the use of HNS does not appear to significantly increase lesion size in normal myocardium despite evidence of increased radiofrequency heating.

Restoration of coronary blood flow after a heart attack can cause reperfusion injury potentially leading to impaired cardiac function, adverse tissue remodeling and heart failure. Iron is an essential biometal that may have a pathologic role in this process. There is a clinical need for a precise noninvasive method to detect iron for risk stratification of patients and therapy evaluation. Here, we report that magnetic susceptibility imaging in a large animal model shows an infarct paramagnetic shift associated with duration of coronary artery occlusion and the presence of iron. Iron validation techniques used include histology, immunohistochemistry, spectrometry and spectroscopy. Further mRNA analysis shows upregulation of ferritin and heme oxygenase. While conventional imaging corroborates the findings of iron deposition, magnetic susceptibility imaging has improved sensitivity to iron and mitigates confounding factors such as edema and fibrosis. Myocardial infarction patients receiving reperfusion therapy show magnetic susceptibility changes associated with hypokinetic myocardial wall motion and microvascular obstruction, demonstrating potential for clinical translation., Restoration of coronary blood flow after a heart attack may lead to reperfusion injury and pathologic iron deposition. Here, the authors perform magnetic susceptibility imaging showing its association with iron in a large animal model of myocardial infarction during wound healing, and showing feasibility in acute myocardial infarction patients undergoing percutaneous coronary intervention.

In patients with nonischemic cardiomyopathy (NICM) little is known about the clinical impact of catheter ablation (CA) of septal ventricular tachycardia (VT) resulting in the collateral injury of the conduction system (CICS).Ninety-five consecutive patients with NICM underwent CA of septal VT. Outcomes in patients with no baseline conduction abnormalities who developed CICS (group 1, n = 28 [29%]) were compared to patients with no CICS (group 2, n = 17 [18%]) and to patients with preexisting conduction abnormalities or biventricular pacing (group 3, n = 50 [53%]). Group-1 patients were younger, had a higher left ventricular ejection fraction and a lower prevalence of New York Heart Association III/IV class compared to group 3 while no significant differences were observed with group 2. After a median follow-up of 15 months, VT recurred in 14% of patients in group 1, 12% in group 2 (P = .94) and 32% in group 3 (P = .08) while death/transplant occurred in 14% of patients in group 1, 18% in group 2 (P = .69) and 28% in group 3 (P = .15). A worsening of left ventricular ejection fraction (LVEF) (median LVEF variation, -5%) was observed in group 1 compared to group 2 (median LVEF variation, 0%; P .01) but not group-3 patients (median LVEF variation, -4%; P = .08) with a consequent higher need for new biventricular pacing in group 1 (43%) compared to group 2 (12%; P = .03) and group 3 (16%; P .01).In patients with NICM and septal substrate, sparing the abnormal substrate harboring the conduction system provides acceptable VT control while preventing a worsening of the systolic function.

Background: The substrate for ventricular tachycardia (VT) in left ventricular (LV) nonischemic cardiomyopathy may be epicardial. We assessed the prevalence, location, endocardial electrograms, and VT ablation outcomes in LV nonischemic cardiomyopathy with isolated epicardial substrate. Methods: Forty-seven of 531 (9%) patients with LV nonischemic cardiomyopathy and VT demonstrated normal endocardial (>1.5 mV)/abnormal epicardial bipolar low-voltage area (LVA, Results: Epicardial bipolar LVA (27.3 cm 2 [interquartile range, 15.8–50.0]) localized to basal (40), mid (8), and apical (3) LV with basal inferolateral LV most common (28/47, 60%). Of 44 endocardial maps available, 40 (91%) had endocardial unipolar LVA (24.5 cm 2 [interquartile range, 9.4–68.5]) and 29 (67%) had characteristic normal amplitude endocardial split electrograms opposite the epicardial LVA. At mean of 34 months, the VT-free survival was 55% after one and 72% after multiple procedures. Greater endocardial unipolar LVA than epicardial bipolar LVA (hazard ratio, 10.66 [CI, 2.63–43.12], P =0.001) and number of inducible VTs (hazard ratio, 1.96 [CI, 1.27–3.00], P =0.002) were associated with VT recurrence. Conclusions: In patients with LV nonischemic cardiomyopathy and VT, the substrate may be confined to epicardial and commonly basal inferolateral. LV endocardial unipolar LVA and normal amplitude bipolar split electrograms identify epicardial LVA. Ablation targeting epicardial VT and substrate achieves good long-term VT-free survival. Greater endocardial unipolar than epicardial bipolar LVA and more inducible VTs predict VT recurrence.

Background: The majority of data regarding tissue substrate for post myocardial infarction (MI) VT has been collected during hemodynamically tolerated VT, which may be distinct from the substrate responsible for VT with hemodynamic compromise (VT-HC). This study aimed to characterize tissue at diastolic locations of VT-HC in a porcine model.Methods: Late Gadolinium Enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging was performed in eight pigs with healed antero-septal infarcts. Seven pigs underwent electrophysiology study with venous arterial-extra corporeal membrane oxygenation (VA-ECMO) support. Tissue thickness, scar and heterogeneous tissue (HT) transmurality were calculated at the location of the diastolic electrograms of mapped VT-HC.Results: Diastolic locations had median scar transmurality of 33.1% and a median HT transmurality 7.6%. Diastolic activation was found within areas of non-transmural scar in 80.1% of cases. Tissue activated during the diastolic component of VT circuits was thinner than healthy tissue (median thickness: 5.5 mm vs. 8.2 mm healthy tissue, p < 0.0001) and closer to HT (median distance diastolic tissue: 2.8 mm vs. 11.4 mm healthy tissue, p < 0.0001). Non-scarred regions with diastolic activation were closer to steep gradients in thickness than non-scarred locations with normal EGMs (diastolic locations distance = 1.19 mm vs. 9.67 mm for non-diastolic locations, p < 0.0001). Sites activated late in diastole were closest to steep gradients in tissue thickness.Conclusions: Non-transmural scar, mildly decreased tissue thickness, and steep gradients in tissue thickness represent the structural characteristics of the diastolic component of reentrant circuits in VT-HC in this porcine model and could form the basis for imaging criteria to define ablation targets in future trials.

In-stent restenosis (ISR) complicates revascularization in the coronary and peripheral arteries. Apolipoprotein A1 (apoA1), the principal protein component of HDL possesses inherent anti-atherosclerotic and anti-restenotic properties. These beneficial traits are lost when wild type apoA1(WT) is subjected to oxidative modifications. We investigated whether local delivery of adeno-associated viral (AAV) vectors expressing oxidation-resistant apoA1(4WF) preserves apoA1 functionality. The efflux of

Background Low QRS amplitude (QRSa), QRS fractionation (QRSf) and longer QRS duration (QRSd) are markers of myocardial fibrosis and inflammation in non-ischemic cardiomyopathy (NICM). Objective To determine if reduction of inflammation with treatment of cardiac sarcoidosis (CS) may reverse these 12 lead ECG parameter changes. Methods 21 patients (pts) with CS and VT ablation with a positive baseline positron emission tomographic (PET 1) scan were studied. All pts received prednisone ≥40 mg for 4 to 8 weeks followed by a taper and maintenance with methotrexate ± low-dose prednisone, Results Pts in PET2(+) vs PET2(−) groups has similar gender (men 89% vs 100%, p=0.42), age (57±8 vs 56±10 years, p=0.8) and LV ejection fraction (41±11 vs 46±11, p=0.31). Baseline 12-lead ECGs showed similar QRSd, ≥2QRSf contiguous leads and QRSa for PET2(+) vs PET2(−); P all >0.15 (Table 1). At 1 yr there was a lower prevalence of ≥2QRSf contiguous leads and strong trend for shorter QRS duration and larger QRSa in lead DI if PET2(−) vs PET2(+). 4 pts demonstrated loss of QRSf 2 contiguous leads and/or increase in QRSa in DI by at least 0.15 mV from baseline if PET2(−) and none if PET2(+). Conclusions In pts with CS and VT, reversal of inflammation may result in a greater QRSa and reduction in QRSf. An increase in QRSa in lead 1 by >0.15mV and/or loss of QRSf identifies a clear positive response to treatment and negative PET at 1 year. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Richard T and Angela Clark Innovation Fund in Cardiovascular Medicine, the Mark S Marchlinski EP Research and Education Fund and the Winkelman Family Fund in Cardiovascular Innovation. Table 1

Ventricular tachycardia (VT) substrate abnormalities in arrhythmogenic right ventricular cardiomyopathy (ARVC) typically involve both the right ventricular (RV) endocardium (ENDO) and epicardium (EPI).The purpose of this study was to examine the prevalence, electrophysiological features, and outcomes of catheter ablation of VT in patients with isolated epicardial substrate (IES) abnormalities.We studied 71 consecutive patients with VT who met Task Force criteria for ARVC and underwent detailed ENDO and EPI mapping. Patients with critical IES demonstrated (1) confluent EPI bipolar abnormal electrograms (EGMs) and (2) no or minor (5.0 cmTwelve patients (17%) had IES. Extensive EPI bipolar low-voltage area (Bi-LVA; 74 ± 40 cmIn patients with ARVC and VT, substrate abnormalities can uncommonly be isolated to the RV EPI. Detection of critical IES may be limited with CMR imaging but suggested by ENDO unipolar EGM abnormalities. EPI ablation eliminates VT in these patients and typically results in long-term VT-free survival.

INTRODUCTION: Ablation of papillary muscles (PMs) for refractory ventricular arrhythmias can often be challenging. The catheter approach and orientation during ablation may affect optimal radiofrequency (RF) delivery. Yet, no previous study investigated the association between catheter orientation and PM lesion size. We evaluated ablation lesion characteristics with various catheter orientations relative to the PM tissue during open irrigated ablation, using a standardized, experimental setting. METHODS: Viable bovine PM was positioned on a load cell in a circulating saline bath. RF ablation was performed over PM tissue at 50 W, with the open irrigated catheter positioned either perpendicular or parallel to the PM surface. Applied force was 10 g. Ablation lesions were sectioned and underwent quantitative morphometric analysis. RESULTS: A catheter position oriented directly perpendicular to the PM tissue resulted in the largest ablation lesion volumes and depths compared with ablation with the catheter parallel to PM tissue (75.26 ± 8.40 mm(3) vs. 34.04 ± 2.91 mm(3), p < .001) and (3.33 ± 0.18 mm vs. 2.24 ± 0.10 mm, p < .001), respectively. There were no significant differences in initial impedance, peak voltage, peak current, or overall decrease in impedance among groups. Parallel catheter orientation resulted in higher peak temperature (41.33 ± 0.28°C vs. 40.28 ± 0.24°C, p = .003), yet, there were no steam pops in either group. CONCLUSION: For PM ablation, catheter orientation perpendicular to the PM tissue achieves more effective and larger ablation lesions, with greater lesion depth. This may have implications for the chosen ventricular access approach, the type of catheter used, consideration for remote navigation, and steerable sheaths.

In arrhythmogenic right ventricular cardiomyopathy (ARVC), abnormal electroanatomic mapping (EAM) areas are proportional to extent of T-wave inversion on 12-lead ECG. We aimed to evaluate local repolarization changes and their relationship to EAM substrate in ARVC. Using unipolar recordings, we analyzed the proportion of negative T waves ≥ 1 mV in depth (NegT), NegT area, Q-Tpeak (QTP), Tpeak-Tend (TPE) intervals and their relationship to bipolar (

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Winkelman family research fund. Background. The arrhythmogenic substrate in nonischemic cardiomyopathy (NICM) characteristically consists of fibrosis with surviving myocytes. We hypothesized that the substrate may be reflected on the 12-lead ECG as depolarization abnormalities (QRS fragmentation [QRSf] and J waves) during sinus rhythm in patients with VT. Methods. Phase I subjects included a retrospective cohort with NICM and VT referred for VT ablation between 2007 and 2020 who had detailed substrate mapping. Phase II subjects included a prospective reference cohort with NICM and No VT referred for primary prevention ICD between 2017 and 2019. All patients had supraventricular rhythm. 12-lead ECGs voltage and presence of QRSf/J waves were compared between phase I and phase II patients. Results. Forty-five (59.2%) patients had epicardial (EPI) VT circuits and EPI LV low voltage. Thirty-one (40.8%) had endocardial (ENDO) VT circuits and Endo LV low voltage. All 38 Phase II subjects had cardiac magnetic resonance imaging (cMRI) with 26 (68.4%) patients demonstrating late gadolinium enhancement (LGE). Lower voltage in the limb leads was present in Phase I (NICM/VT) [DI (0.63 ± 0.33 vs 0.87 ± 0.4, p = 0.002), DII (0.6 ± 0.27 vs 0.85 ± 0.36, p Conclusions. In patients with NICM and VT the presence and location of LV scarring can be predicted by depolarization abnormalities on 12-lead ECG. ECG characteristics NICM VT and EPI substrate(n = 45) NICM VT and ENDO substrate(n = 31) p value NICM No VT and LGE(n = 26) NICM No VT and No LGE(n = 12) p value QRSf in 2 contiguous leads 35 (77.7%) 23 (74.1%) p = 0.71 19 (73%) 5 (41.7%) p = 0.06 QRSf in lead DII, DIII, AVF 30 (66.6%) 21 (67.7%) p = 0.92 17 (65.4%) 5 (41.7%) p = 0.16 QRSf in lead DI, AVL, V5, V6 22 (48.9%) 11 (35.5%) p = 0.24 10 (38.5%) 3 (25%) p = 0.41 QRSf in lead V1, V2, V3, V4 10 (22.2%) 7 (22.6%) p = 0.97 9 (34.6%) 2 (16.7%) p = 0.25

Severe endoscopically detected esophageal thermal lesions (EDELs) have been associated with higher risk of progression to atrio-esophageal fistula (AEF) following radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). We sought to evaluate safety and feasibility of active esophageal cooling using the Attune Medical Esophageal Heat Transfer Device (EnsoETM) to limit frequency or severity of EDELs.We sought To evaluate safety and feasibility of active esophageal cooling using the Attune Medical Esophageal Heat Transfer Device (EnsoETM) to limit frequency or severity of EDELs METHODS: Consecutive patients undergoing first-time RFCA were randomized in a 1:1 fashion to esophageal cooling (device group) or standard temperature monitoring (control group). Ablation on the posterior wall was performed with a maximum power of 30W for up to 20s. All patients underwent EGD within 48 h. Endoscopy findings were classified as 1, erythema-mild injury; 2, superficial ulceration-moderate injury; 3, deep ulceration-significant injury; and 4, fistula/perforation. Severe EDELs were defined as grade 3 or 4 lesions.Forty-four patients completed the study (22 device group, 22 control group). Adjunctive posterior wall isolation was performed more frequently in the device group (11/22, 50% vs. 4/22, 18%). EDELs were detected in 5/22 (23%) control group patients, with mild or moderate injury in 2/5 patients (40%) and severe thermal injury in 3/5 patients (60%). In the device group, EDELs were detected in 8/22 (36%) patients, with mild or moderate injury in 7/8 (87%) patients and severe thermal injury in 1/8 (12%) patients. There was no acute perforation or AEF during follow-up.Active esophageal cooling may reduce the occurrence of severe EDELs. A larger randomized study is warranted to further evaluate the benefit of this strategy.

A robotic system for automatically navigating ultrasound (US) imaging catheters can provide real-time intra-cardiac imaging for diagnosis and treatment while reducing the need for clinicians to perform manual catheter steering. Clinical deployment of such a system requires accurate navigation despite the presence of disturbances including cyclical physiological motions (e.g., respiration). In this work, we report results from in vivo trials of automatic target tracking using our system, which is the first to navigate cardiac catheters with respiratory motion compensation. The effects of respiratory disturbances on the US catheter are modeled and then applied to four-degree-of-freedom steering kinematics with predictive filtering. This enables the system to accurately steer the US catheter and aim the US imager at a target despite respiratory motion disturbance. In vivo animal respiratory motion compensation results demonstrate automatic US catheter steering to image a target ablation catheter with 1.05 mm and 1.33° mean absolute error. Robotic US catheter steering with motion compensation can improve cardiac catheterization techniques while reducing clinician effort and X-ray exposure.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) appears in most patients to be an inherited disease characterized by fibrofatty replacement of myocytes extending from the epicardium to the endocardium in the right ventricle. The disease process results in life‑threatening ventricular arrhythmias and ventricular dysfunction. In the absence of a gold‑standard diagnostic test and despite the progress in imaging techniques, ARVC is often misdiagnosed and earlier detection of the disease is challenging. Preprocedural identification and localization of the substrate can be determined from the analysis of surface electrocardiography and cardiac magnetic resonance imaging. Typically, perivalvular arrhythmogenic substrate, defined by electroanatomic mapping, is present and can be isolated to the epicardium. Ablation targets are further identified with activation, entrainment, and local electrogram abnormalities based on detailed electroanatomic mapping. Extensive combined endo / epicardial ablation performed in experienced centers is frequently required to prevent ventricular tachycardia (VT). Catheter ablation significantly reduces recurrences of VT, appropriate implantable cardioverter‑defibrillator shocks, and the use of antiarrhythmic drugs and cardiac transplant as a management strategy for refractory arrhythmias is rarely required. Progression of the disease is poorly understood and may require a distinct triggering mechanism. Biventricular involvement is more common than previously recognized. However, left ventricular involvement leading to significant terminal heart failure is fortunately uncommon and left ventricular tachycardias are also infrequent. Many questions remain regarding prevention and management of coexisting tricuspid valve regurgitation, atrial arrhythmias, and intracardiac thrombosis. Although data on genotype‑phenotype correlations is growing, long‑term follow‑up studies of families with ARVC are still lacking. Ongoing research will contribute to better understanding of this pathological condition.

Ablation of the left atrium using either radiofrequency (RF) or cryothermal energy is an effective treatment for atrial fibrillation (AF) and is the most frequent type of cardiac ablation procedure performed. Although generally safe, collateral injury to surrounding structures, particularly the esophagus, remains a concern. Cooling or warming the esophagus to counteract the heat from RF ablation, or the cold from cryoablation, is a method that is used to reduce thermal esophageal injury, and there are increasing data to support this approach. This protocol describes the use of a commercially available esophageal temperature management device to cool or warm the esophagus to reduce esophageal injury during left atrial ablation. The temperature management device is powered by standard water-blanket heat exchangers, and is shaped like a standard orogastric tube placed for gastric suctioning and decompression. Water circulates through the device in a closed-loop circuit, transferring heat across the silicone walls of the device, through the esophageal wall. Placement of the device is analogous to the placement of a typical orogastric tube, and temperature is adjusted via the external heat-exchanger console.

This study sought to examine the impact of periprocedural acute kidney injury (AKI) in scar-related ventricular tachycardia (VT) patients undergoing radiofrequency catheter ablation (RFCA) on short- and long-term outcomes.The clinical significance of periprocedural AKI in patients with scar-related VT undergoing RFCA has not been previously investigated.This study included 317 consecutive patients with scar-related VT undergoing RFCA (age: 64 ± 13 years, mean left ventricular ejection fraction: 33 ± 13%, 55% ischemic cardiomyopathy). Periprocedural AKI was defined as an absolute increase in creatinine of ≥0.3 mg/dl over 48 h or an increase of1.5× the baseline values within 1 week post-procedure.Periprocedural AKI occurred in 31 patients (10%). Independent predictors of AKI included chronic kidney disease (odds ratio [OR]: 3.43; 95% confidence interval [CI]: 1.48 to 7.96; p = 0.004), atrial fibrillation (OR: 2.42; 95% CI: 1.01 to 5.78; p = 0.047), and peri-procedural acute hemodynamic decompensation (OR: 3.98; 95% CI: 1.17 to 13.52; p = 0.003). After a median follow-up of 39 months (interquartile range: 6 to 65 months), 95 patients (30%) died. Periprocedural AKI was associated with increased risk of early mortality (within 30 days; hazard ratio [HR]: 9.91; 95% CI: 2.87 to 34.22; p 0.001) and late mortality (within 1 year) (HR: 4.57; 95% CI: 2.08 to 10.05; p 0.001). After multivariable adjustment, AKI remained independently associated with increased risk of early and late mortality (HR: 4.49; 95% CI: 1.1 to 18.36; p = 0.04, and HR: 3.28; 95% CI: 1.43 to 7.49; p = 0.005, respectively).Periprocedural AKI occurs in 10% of patients undergoing RFCA of scar-related VT and is strongly associated with increased risk of early and late post-procedural mortality.

Background: Data characterizing structural changes of arrhythmogenic right ventricular (RV) cardiomyopathy are limited. Methods: Patients presenting with left bundle branch block ventricular tachycardia in the setting of arrhythmogenic RV cardiomyopathy with procedures separated by at least 9 months were included. Results: Nineteen consecutive patients (84% males; mean age 39±15 years [range, 20–76 years]) were included. All 19 patients underwent 2 detailed sinus rhythm electroanatomic endocardial voltage maps (average 385±177 points per map; range, 93–847 points). Time interval between the initial and repeat ablation procedures was mean 50±37 months (range, 9–162). No significant progression of voltage was observed (bipolar: 38 cm 2 [interquartile range (IQR), 25–54] versus 53 cm 2 [IQR, 25–65], P =0.09; unipolar: 116 cm 2 [IQR, 61–209] versus 159 cm 2 [IQR, 73–204], P =0.36) for the entire study group. There was a significant increase in RV volumes (percentage increase, 28%; 206 mL [IQR, 170–253] versus 263 mL [IQR, 204–294], P P =0.006; unipolar: Spearman ρ, 0.5743, P =0.03). Most patients with progressive RV dilatation (8/14, 57%) had moderate (2 patients) or severe (6 patients) tricuspid regurgitation recorded at either initial or repeat ablation procedure. Conclusions: In patients with arrhythmogenic RV cardiomyopathy presenting with recurrent ventricular tachycardia, >10% increase in RV endocardial surface area of bipolar voltage consistent with scar is uncommon during the intermediate term. Most recurrent ventricular tachycardias are localized to regions of prior defined scar. Voltage indexed scar area at baseline but not changes in scar over time is associated with progressive increase in RV size and is consistent with adverse remodeling but not scar progression. Marked tricuspid regurgitation is frequently present in patients with arrhythmogenic RV cardiomyopathy who have progressive RV dilation.

Wearable and implantable devices require conductive, stretchable and biocompatible materials. However, obtaining composites that simultaneously fulfil these requirements is challenging due to a trade-off between conductivity and stretchability. Here, we report on Ag–Au nanocomposites composed of ultralong gold-coated silver nanowires in an elastomeric block-copolymer matrix. Owing to the high aspect ratio and percolation network of the Ag–Au nanowires, the nanocomposites exhibit an optimized conductivity of 41,850 S cm−1 (maximum of 72,600 S cm−1). Phase separation in the Ag–Au nanocomposite during the solvent-drying process generates a microstructure that yields an optimized stretchability of 266% (maximum of 840%). The thick gold sheath deposited on the silver nanowire surface prevents oxidation and silver ion leaching, making the composite biocompatible and highly conductive. Using the nanocomposite, we successfully fabricate wearable and implantable soft bioelectronic devices that can be conformally integrated with human skin and swine heart for continuous electrophysiological recording, and electrical and thermal stimulation. A highly conductive, biocompatible and stretchable nanocomposite based on ultralong gold-coated silver nanowires allows for the realization of wearable and implantable bioelectronics.

Objectives This study sought to examine the biophysical properties of high-power and short-duration (HP-SD) radiofrequency ablation for pulmonary vein isolation. Background Pulmonary vein isolation is the cornerstone of atrial fibrillation ablation. However, pulmonary vein reconnection is frequent and is often the result of catheter instability, tissue edema, and a reversible nontransmural injury. We postulated that HP-SD ablation increases lesion-to-lesion uniformity and transmurality. Methods This study included 20 swine and a novel open-irrigated ablation catheter with a thermocouple system able to record temperature at the catheter-tissue interface (QDOT Micro Catheter). Step 1 compared 3 HP-SD ablation settings: 90 W/4 s, 90 W/6 s, and 70 W/8 s in a thigh muscle preparation. Ablation at 90 W/4 s was identified as the best compromise between lesion size and safety parameters, with no steam-pop or char. In step 2, a total of 174 single ablation applications were performed in the beating heart and resulted in 3 (1.7%) steam-pops, all occurring at catheter-tissue interface temperature ≥85°C. Additional 233 applications at 90 W/4 s and temperature limit of 65°C were applied without steam-pop. Step 3 compared the presence of gaps and lesion transmurality in atrial lines and pulmonary vein isolation between HP-SD (90 W/4 s, T ≤65°C) and standard (25 W/20 s) ablation. Results HP-SD ablation resulted in 100% contiguous lines with all transmural lesions, whereas standard ablation had linear gaps in 25% and partial thickness lesions in 29%. Ablation with HP-SD produced wider lesions (6.02 ± 0.2 mm vs. 4.43 ± 1.0 mm; p = 0.003) at similar depth (3.58 ± 0.3 mm vs. 3.53 ± 0.6 mm; p = 0.81) and improved lesion-to-lesion uniformity with comparable safety end points. Conclusions In a preclinical model, HP-SD ablation (90 W/4 s, T ≤65°C) produced an improved lesion-to-lesion uniformity, linear contiguity, and transmurality at a similar safety profile of conventional ablation.

BACKGROUND Myocardial infarction (MI) survivors are at risk of complications including heart failure and malignant arrhythmias. PURPOSE We undertook serial imaging of swine following MI with the aim of characterizing the longitudinal left ventricular (LV) remodeling in a translational model of ischemia-reperfusion-mediated MI. ANIMAL MODEL Eight Yorkshire swine underwent mid left anterior descending coronary artery balloon occlusion to create an ischemia-reperfusion experimental model of MI. FIELD STRENGTH/SEQUENCES 1.5T Philips Achieva scanner. Serial cardiac MRI was performed at 16, 33, and 62 days post-MI, including cine imaging, native and postcontrast T1 , T2 and dark-blood late gadolinium enhanced (DB-LGE) scar imaging. ASSESSMENT Regions of interest were selected on the parametric maps to assess native T1 and T2 in the infarct and in remote tissue. Volume of enhanced tissue, nonenhanced tissue, and gray zone were assessed from DB-LGE imaging. Volumes, cardiac function, and strain were calculated from cine imaging. STATISTICAL TESTS Parameters estimated at more than two timepoints were compared with a one-way repeated measures analysis of variance. Parametric mapping data were analyzed using a generalized linear mixed model corrected for multiple observations. A result was considered statistically significant at P