Atrioesophageal Fistula Rates Before and After Adoption of Active Esophageal Cooling During Atrial Fibrillation Ablation.

BACKGROUND: Active esophageal cooling reduces the incidence of endoscopically identified severe esophageal lesions during radiofrequency (RF) catheter ablation of the left atrium for the treatment of atrial fibrillation. A formal analysis of the atrioesophageal fistula (AEF) rate with active esophageal cooling has not previously been performed. OBJECTIVES: The authors aimed to compare AEF rates before and after the adoption of active esophageal cooling. METHODS: This institutional review board (IRB)-approved study was a prospective analysis of retrospective data, designed before collecting and analyzing the real-world data. The number of AEFs occurring in equivalent time frames before and after adoption of cooling using a dedicated esophageal cooling device (ensoETM, Attune Medical) were quantified across 25 prespecified hospital systems. AEF rates were then compared using generalized estimating equations robust to cluster correlation. RESULTS: A total of 14,224 patients received active esophageal cooling during RF ablation across the 25 hospital systems, which included a total of 30 separate hospitals. In the time frames before adoption of active cooling, a total of 10,962 patients received primarily luminal esophageal temperature (LET) monitoring during their RF ablations. In the preadoption cohort, a total of 16 AEFs occurred, for an AEF rate of 0.146%, in line with other published estimates for procedures using LET monitoring. In the postadoption cohort, no AEFs were found in the prespecified sites, yielding an AEF rate of 0% (P < 0.0001). CONCLUSIONS: Adoption of active esophageal cooling during RF ablation of the left atrium for the treatment of atrial fibrillation was associated with a significant reduction in AEF rate.

Slow-pathway visualization by using voltage-time relationship: A novel technique for identification and fluoroless ablation of atrioventricular nodal reentrant tachycardia.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is treatable by catheter ablation. Advances in mapping-system technology permit fluoroless workflow during ablations. As national practice trends toward fluoroless approaches, easily obtained, reproducible methods of slow-pathway identification, and ablation become increasingly important. We present a novel method of slow-pathway identification and initial ablation results from this method. METHODS AND RESULTS: We examined AVNRT ablations performed at our institution over a 12-month period. In these cases, the site of the slow pathway was predicted by latest activation in the inferior triangle of Koch during sinus rhythm. Ablation was performed in this region. Proximity of the predicted site to the successful ablation location, complication rates, and patient outcomes were recorded. Junctional rhythm was seen in 40/41 ablations (98%) at the predicted site (mean, 1.3 lesions and median, 1 lesion per case). One lesion was defined as 5 mm of ablation. The initial ablation was successful in 39/41 cases (95%); in two cases, greater or equal to 2 echo beats were detected after the initial ablation, necessitating further lesion expansion. In 8/41 cases (20%), greater than one lesion was placed during initial ablation before attempted reinduction. Complications included one transient heart block and one transient PR prolongation. During follow-up (median, day 51), one patient had lower-extremity deep-vein thrombosis and pulmonary embolus, and one had a lower-extremity superficial venous thrombosis. There was one tachycardia recurrence, which prompted a redo ablation. CONCLUSIONS: Mapping-system detection of late-activation, low-amplitude voltage during sinus rhythm provides an objective, and fluoroless means of identifying the slow pathway in typical AVNRT.

Confirming pericardial access by using impedance measurements from a micropuncture needle.

BACKGROUND: Pericardial access is complicated by two difficulties: confirming when the needle tip is in the pericardial space, and avoiding complications during access, such as inadvertently puncturing other organs. Conventional imaging tools are inadequate for addressing these difficulties, as they lack soft-tissue markers that could be used as guidance during access. A system that can both confirm access and avoid inadvertent organ injury is needed. METHODS: A 21G micropuncture needle was modified to include two small electrodes at the needle tip. With continuous bioimpedance monitoring from the electrodes, the needle was used to access the pericardium in porcine models (n  =  4). The needle was also visualized in vivo by using an electroanatomical map (n  =  2). Bioimpedance data from different tissues were analyzed retrospectively. RESULTS: Bioimpedance data collected from the subcutaneous space (992.8 ± 13.1 Ω), anterior mediastinum (972.2 ± 14.2 Ω), pericardial space (323.2 ± 17.1 Ω), mid-myocardium (349.7 ± 87.6 Ω), right ventricular cavity (235.0 ± 9.7 Ω), lung (1142.0 ± 172.0 Ω), liver (575.0 ± 52.6 Ω), and blood (177.5 ± 1.9 Ω) differed significantly by tissue type (P < .01). Phase data in the frequency domain correlated well with the needle being in the pericardial space. A simple threshold analysis effectively separated lung (threshold  =  1120.0 Ω) and blood (threshold  =  305.9 Ω) tissues from the other tissue types. CONCLUSIONS: Continuous bioimpedance monitoring from a modified micropuncture needle during pericardial access can be used to clearly differentiate tissues. Combined with traditional imaging modalities, this system allows for confirming access to the pericardial space while avoiding inadvertent puncture of other organs, creating a safer and more efficient needle-access procedure.

Author Correction: Synchronized Biventricular Heart Pacing in a Closed-chest Porcine Model based on Wirelessly Powered Leadless Pacemakers.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Synchronized Biventricular Heart Pacing in a Closed-chest Porcine Model based on Wirelessly Powered Leadless Pacemakers.

About 30% of patients with impaired cardiac function have ventricular dyssynchrony and seek cardiac resynchronization therapy (CRT). In this study, we demonstrate synchronized biventricular (BiV) pacing in a leadless fashion by implementing miniaturized and wirelessly powered pacemakers. With their flexible form factors, two pacemakers were implanted epicardially on the right and left ventricles of a porcine model and were inductively powered at 13.56 MHz and 40.68 MHz industrial, scientific, and medical (ISM) bands, respectively. The power consumption of these pacemakers is reduced to µW-level by a novel integrated circuit design, which considerably extends the maximum operating distance. Leadless BiV pacing is demonstrated for the first time in both open-chest and closed-chest porcine settings. The clinical outcomes associated with different interventricular delays are verified through electrophysiologic and hemodynamic responses. The closed-chest pacing only requires the external source power of 0.3 W and 0.8 W at 13.56 MHz and 40.68 MHz, respectively, which leads to specific absorption rates (SARs) 2-3 orders of magnitude lower than the safety regulation limit. This work serves as a basis for future wirelessly powered leadless pacemakers that address various cardiac resynchronization challenges.

Isolated hemopericardium after initiation of rivaroxaban: Implications and potential mechanisms.

Direct oral anticoagulants have become increasingly used for atrial fibrillation and venothromboembolic disease. Thus far, there have been a few published cases of pericardial effusion associated with rivaroxban. However, there has been little published regarding the effects of concurrent medications and their effect on the cytochrome enzyme systems involved in rivaroxaban metabolism. We present a case of a 76-year-old female who develops a spontaneous haemopericardium after initiating rivaroxaban. After thorough medical reconciliation, we offer pharmacokinetic mechanisms that may have contributed to the haemopericardium. This case demonstrates the importance of reviewing patients medication lists and utilizing basic pharmacokinetics to prevent adverse events.

A Multi-site Heart Pacing Study Using Wirelessly Powered Leadless Pacemakers.

In this work, we report an energy-efficient switched capacitor based millimeter-scale pacemaker (5 mm ×7.5 mm) and a multi-receiver wireless energy transfer system operating at around 200 MHz, and use them in a proof-of-concept multi-site heart pacing study. Two pacemakers were placed on two beating Langendorff rodent heart models separately. By utilizing a single transmitter positioned 20-30 cm away, both Langendorff hearts captured the stimuli simultaneously and were electromechanically coupled. This study provides an insight for future energy-efficient and distributed cardiac pacemakers that can offer cardiac resynchronization therapies.

Leadless multisite pacing: A feasibility study using wireless power transfer based on Langendorff rodent heart models.

INTRODUCTION: Fifteen to thirty percent of patients with impaired cardiac function have ventricular dyssynchrony and warrant cardiac resynchronization therapy (CRT). While leadless pacemakers eliminate lead-related complications, their current form factor is limited to single-chamber pacing. In this study, we demonstrate the feasibility of multisite, simultaneous pacing using miniaturized pacing nodes powered through wireless power transfer (WPT). METHODS: A wireless energy transfer system was developed based on resonant coupling at approximately 200 MHz to power multiple pacing nodes. The pacing node comprises circuitry to efficiently convert the harvested energy to output stimuli. To validate the use of these pacing nodes, ex vivo studies were carried out on Langendorff rodent heart models (n = 4). To mimic biventricular pacing, two beating Langendorff rodent heart models, kept 10 cm apart, were paced using two distinct pacing nodes, each attached on the ventricular epicardial surface of a given heart. RESULTS: All ex vivo Langendorff heart models were successfully paced with a simple coil antenna at 2 to 3 cm from the pacing node. The coil was operated at 198 MHz and 0.3 W. Subsequently, simultaneous pacing of two Langendorff heart models 30 cm apart using an output power of 5 W was reliably demonstrated. CONCLUSION: WPT provides a feasible option for multisite, wireless cardiac pacing. While the current system remains limited in design, it offers support and a conceptual framework for future iterations and eventual clinical utility.

Incidence, Predictors, and Significance of Ventricular Arrhythmias in Patients With Continuous-Flow Left Ventricular Assist Devices: A 15-Year Institutional Experience.

OBJECTIVES: The aim of this study was to evaluate the incidence, predictors, and associated mortality of pre-implantation, early, and late ventricular arrhythmias (VAs) in patients receiving continuous-flow left ventricular assist devices (CFLVADs). BACKGROUND: VAs are common both pre- and post-implantation of left ventricular assist devices. Limited data exist on their prognostic impact in contemporary CFLVADs. METHODS: A retrospective review was performed to identify patients who underwent CFLVAD implantation between 2000 and 2015 with 2 years of follow-up. All VAs, defined as ventricular fibrillation, ventricular tachycardia lasting >30 s, or a ventricular rhythm requiring defibrillation, were analyzed. VAs occurring within 30 days of implantation were defined as early. Recorded outcomes included death and receipt of cardiac transplant. RESULTS: A total of 517 patients were included for analysis. Early VAs were associated with a significant reduction in survival (hazard ratio: 1.83; 95% confidence interval: 1.28 to 2.61; p = 0.001) compared with patients with late or no VAs. Pre-implantation variables independently predictive of early VAs included prior cardiac surgery (odds ratio: 1.90; 95% confidence interval: 1.09 to 3.32; p = 0.023) and pre-CFLVAD ventricular tachycardia storm (odds ratio: 3.15; 95% confidence interval: 1.49 to 6.69; p = 0.003). The incidence of early VAs from 2000 to 2007 was as high as 47%, whereas the highest incidence from 2008 to 2015 was <22%. CONCLUSIONS: VAs within 30 days after CFLVAD implantation are associated with an increased risk for death. Predictors of early VAs include prior cardiac surgery and pre-CFLVAD ventricular tachycardia storm. Temporal trends have shown a decrease in VA from 2000 to 2015. Strategies to reduce arrhythmia burden shortly after CFLVAD implantation warrant further investigation.

Near-field impedance accurately distinguishes among pericardial, intracavitary, and anterior mediastinal position.

INTRODUCTION: Epicardial catheter ablation is increasingly used to treat arrhythmias with an epicardial component. Nevertheless, percutaneous epicardial access remains associated with a significant risk of major complications. Developing a technology capable of confirming proper placement within the pericardial space could decrease complication rates. The purpose of this study was to examine differences in bioimpedance among the pericardial space, anterior mediastinum, and right ventricle. METHODS: An ovine model (n = 3) was used in this proof-of-concept study. A decapolar catheter was used to collect bipolar impedance readings; data were collected between each of five electrode pairs of varying distances. Data were collected from three test regions: the pericardial space, anterior mediastinum, and right ventricle. A control region in the inferior vena cava was used to normalize the data from the test regions. Analysis of variance was used to test for differences among regions. RESULTS: A total of 10 impedance values were collected in each animal between each of the five electrode pairs in the three test regions (n = 340) and the control region (n = 145). The average normalized impedance values were significantly different among the pericardial space (1.760 ± 0.370), anterior mediastinum (3.209 ± 0.227), and right ventricle (1.024 ± 0.207; P < 0.0001). In post hoc testing, the differences between each pair of regions were significant, as well (P < 0.001 for all). CONCLUSION: Impedance values are significantly different among these three anatomical compartments. Therefore, impedance can be potentially used as a means to guide percutaneous epicardial access.