James P. Hummel

N-acetylcysteine treats intravenous amiodarone induced liver injury

We report a case of intravenous (IV) amiodarone drug induced liver injury (DILI). The patient received IV N-acetylcysteine (NAC) which resulted in a rapid improvement in liver enzymes. While the specific mechanisms for the pathogenesis of IV amiodarone DILI and the therapeutic action of IV NAC are both unknown, this case strongly implies at least some commonality. Because IV amiodarone is indicated for the treatment of serious cardiac arrhythmias in an intensive care unit setting, some degree of ischemic hepatitis is likely a cofactor in most cases.

Arrhythmias After Left Ventricular Assist Device Implantation: Incidence and Management

The use of mechanical circulatory support has become an increasingly common practice in patients with heart failure, whether used as bridge to transplantation or as destination therapy. The last couple of decades has seen a drastic change in the functioning of the left ventricular assist devices (LVAD), changing from the first generation devices running on pulsatile flow to the current continuous flow devices. Atrial and ventricular arrhythmias are common among heart failure patients, and though the systematic circulation is well supported in patients on mechanical circulatory support, these arrhythmias can still be the cause of detrimental symptoms and lead to potentially fatal outcomes. Several studies have shown that mortality rates in LVAD recipients secondary to lethal arrhythmias are uncommon, and newer generation continuous flow devices particularly seem to support hemodynamic support well. While it is common practice to implant ICDs in patients with LVADs and a history of ventricular arrhythmias, the efficacy behind this practice at preventing sudden death in this population is unknown. In this review, we highlight what is already known about the complications, management and treatment of atrial and ventricular arrhythmias in patients with LVAD devices.

Challenges and Outcomes of Posterior Wall Isolation for Ablation of Atrial Fibrillation

Background The left atrial posterior wall (PW) often contains sites required for maintenance of atrial fibrillation (AF). Electrical isolation of the PW is an important feature of all open surgeries for AF. This study assessed the ability of current ablation techniques to achieve PW isolation (PWI) and its effect on recurrent AF. Methods and Results Fifty‐seven consecutive patients with persistent or high‐burden paroxysmal AF underwent catheter ablation, which was performed using an endocardial‐only (30) or a hybrid endocardial–epicardial procedure (27). The catheter ablation lesion set included pulmonary vein antral isolation and a box lesion on the PW (roof and posterior lines). Success in creating the box lesion was assessed as electrical silence of the PW (voltage <0.1 mV) and exit block in the PW with electrical capture. Cox proportional hazards models were used for analysis of AF recurrence. PWI was achieved in 21 patients (36.8%), more often in patients undergoing hybrid ablation than endocardial ablation alone (51.9% versus 23.3%, P=0.05). Twelve patients underwent redo ablation. Five of 12 had a successful procedural PWI, but all had PW reconnection at the redo procedure. Over a median follow‐up of 302 days, 56.1% of the patients were free of atrial arrhythmias. No parameter including procedural PWI was a statistically significant predictor of recurrent atrial arrhythmias. Conclusions PWI during catheter ablation for AF is difficult to achieve, especially with endocardial ablation alone. Procedural achievement of PWI in this group of patients was not associated with a reduction in recurrent atrial arrhythmias, but reconnection of the PW was common.

Reduction of Arrhythmia Burden and Reverse Remodeling in Patients with Persistent Atrial Fibrillation and Severe Atrial Remodeling: The Benefits of Hybrid Ablation.

Nonpharmacologic treatment of patients with persistent, and longstanding persistent, atrial fibrillation remains problematic. Single procedure success rates of catheter ablation are low (c50%), and multiple procedures, often with additional pharmacologic therapy, are frequently required for rhythm control. These patients are challenging to treat not only because of the chronicity of their arrhythmia but also because of the left atrial remodeling that accompanies their atrial fibrillation. Additionally, atrial fibrillation rarely exists in isolation. Concomitant valvular, ischemic, hypertensive, and other structural heart disease complicate nonpharmacologic management. Success of nonpharmacologic management depends on the surgical technique under consideration. Pure catheter ablation, hybrid catheter and epicardial surgical ablation, and variants of the Cox maze procedure all have their proponents, although, because it is minimally invasive and widely available, most patients will undergo a catheter-based procedure at least in the first instance. Selection of the initial surgical approach should ideally be guided by the chronicity of the arrhythmia, the degree of left atrial remodeling and other heart disease, and by practical considerations—for example, whether or not the patient has had a previous thoracotomy. But selection of approach should also be guided by anticipated success. This is obviously guided by the likelihood of arrhythmia control, but reversal of atrial and other cardiac remodeling should also be included in the decision tree. Assessment of the relative success rate for any surgical approach depends almost entirely on comparisons of separate patient series because few

Editorial commentary: Virtual medicine—A better reality?

The last decade has witnessed an explosion in amount and variety of digital health-related data available to both patient and health care provider, which will undoubtedly have a profound influence on the practice of medicine. Increasingly, information could be obtained from smart phones and other commercial external devices, electronic medical record systems, wireless transmission through implantable, wearable, or stand-alone medical devices, and greater access to patients using video and other telemedicine applications. Cardiology has taken the lead in the use of telemonitoring for direct patient care. Integration of remotely collected cardiac data into clinical practice has taken several forms—(1) stand-alone systems that transmit information about heart rate, blood pressure, weights, symptoms, etc.; (2) wearable monitors (e.g., Holter, event, and mobile telemetry monitors) used for detection and diagnosis of arrhythmias and ambulatory blood pressures; (3) implanted therapeutic devices such as pacemakers and defibrillators; and (4) implanted monitoring devices (e.g., pulmonary artery pressure and implantable loop monitors). Remote monitoring has revolutionized implantable device follow-up by allowing surveillance and remote detection of device, disease, and physiological parameters, thereby potentially eliminating the need for many routine in-office device checks. Devices with wireless capability can automatically transmit alerts to clinicians allowing for early identification of clinically actionable events such as atrial fibrillation, ventricular arrhythmias, device/lead malfunction, and battery depletion. Indeed, large observational studies have shown an association between the use of remote monitoring and

Non-Inducibility or termination as endpoints of atrial fibrillation ablation: What is their role?

Catheter ablation is widely used to treat drug-refractory, symptomatic atrial fibrillation (AF). However, beyond pulmonary vein isolation, there remains little consensus on the recommended approach to ablation both in paroxysmal or persistent AF patients. Although ancillary ablation strategies are often used, the lack of a clear endpoint for AF ablation makes it challenging to evaluate their importance. Non-inducibility and termination of AF during AF ablation have been advocated as potential endpoints. Several studies have attempted to assess their role in an AF ablation protocol. However, the data for non-inducibility and termination as endpoints are mixed. Moreover, there are a number of limitations in the studies reported and limitations of the endpoints themselves. It is likely that non-inducibility or termination of AF during AF ablation may be markers of less structural remodeling rather than true endpoints for ablation. Herein, we review the relevant literature on the topic of inducibility and termination with respect to AF ablation and attempt to draw conclusions with guidance to further investigation.

Luminal esophageal temperature monitoring to reduce esophageal thermal injury during catheter ablation for atrial fibrillation: A review

Over the past decade, catheter ablation for atrial fibrillation has emerged as an important rhythm control strategy. One of the most dreaded complications of this procedure is atrio-esophageal (AE) fistula formation, which is relatively rare but usually fatal. Esophageal tissue injury during ablation appears to be a precursor to the formation of AE fistulae. Luminal esophageal temperature (LET) monitoring is one of the most commonly utilized strategies to mitigate this risk, despite little evidence that it reduces esophageal injury. The incidence of AE fistulae appears to be on the rise, despite the widespread use of LET monitoring. This may be due to the advent of improved large lesion technology including force-sensing catheters and the use of high power, although AE fistulae have also been observed with the use of low power along the left atrial posterior wall. Currently available discrete sensors probes, whether single or multiple, do not appear to significantly reduce injury rates. The purpose of this manuscript is to systematically review the incidence of esophageal thermal injury with and without LET monitoring and review the factors that may be associated with increased risk of injury.

Physiologic and Histopathologic Effects of Targeted Lung Denervation in an Animal Model

Parasympathetic efferent innervation of the lung is the primary source of lung acetylcholine. Inhaled long-acting anticholinergics improve lung function and symptoms in patients with chronic obstructive pulmonary disease. Targeted lung denervation (TLD), a bronchoscopic procedure intended to disrupt pulmonary parasympathetic inputs, is an experimental treatment for chronic obstructive pulmonary disease. The physiologic and histologic effects of TLD have not previously been assessed. Eleven sheep and two dogs underwent circumferential ablation of the main bronchi with simultaneous balloon surface cooling using a lung denervation system (Nuvaira, Inc., Minneapolis, MN). Changes in pulmonary air flow resistance were monitored before and following TLD. Four animals were assessed for the presence or abolishment of the sensory axon-mediated Hering-Breuer reflex before and following TLD. Six sheep were histologically evaluated 30 days post-TLD for the extent of lung denervation (axonal staining) and effect on peribronchial structures near the treatment site. No adverse clinical effects were seen in any treated animals. TLD produced a ~30% reduction in pulmonary resistance and abolished the sensory-mediated Hering-Breuer reflex. Axonal staining was consistently decreased 60% at 30 days after TLD. All treated airways exhibited 100% epithelial integrity. Damage to other peribronchial structures was minimal. Tissue 1 cm proximal and distal to the treatment was normal, and the esophagus and periesophageal vagus nerve branches were unaffected. TLD treatment effectively denervates the lung while protecting the bronchial epithelium and minimizing effects on peribronchial structures. NEW & NOTEWORTHY The feasibility of targeted lung denervation, a new minimally invasive therapy for obstructive lung disease, has been demonstrated in humans with preliminary clinical studies demonstrating improvement in symptoms, pulmonary function, and exercise capacity in patients with chronic obstructive pulmonary disease. This preclinical animal study demonstrates the ability of targeted lung denervation to disrupt vagal inputs to the lung and details its physiologic and histopathologic effects.