Dorothy J. Ladewig

Relevance of Endocavitary Structures in Ablation Procedures for Ventricular Tachycardia

Endocavitary Structures and Ventricular Tachycardia Ablation. Background: Radiofrequency (RF) ablation for ventricular tachycardia (VT) has high failure rates. Whether endocavitary structures (ECS) such as the papillary muscles (PMs), moderator bands (MBs), or false tendons (FTs) impact VT ablation is unknown.

Utilization of Retrograde Right Bundle Branch Block to Differentiate Atrioventricular Nodal from Accessory Pathway Conduction

Introduction: Defining whether retrograde ventriculoatrial (V‐A) conduction is via the AV node (AVN) or an accessory pathway (AP) is important during ablation procedures for supraventricular tachycardia (SVT). With the introduction of ventricular extrastimuli (VEST), retrograde right bundle branch block (RBBB) may occur, prolonging the V‐H interval, but only when AV node conduction is present. We hypothesized that when AP conduction was present, the V‐A interval would increase less than the V‐H interval, whereas with retrograde nodal conduction, the V‐A interval would increase at least as much as the V‐H interval.

Transvenous Stimulation of the Renal Sympathetic Nerves Increases Systemic Blood Pressure: A Potential New Treatment Option for Neurocardiogenic Syncope

Neurocardiogenic syncope (NCS) is a common and sometimes debilitating disorder, with no consistently effective treatment. NCS is due to a combination of bradycardia and vasodilation leading to syncope. Although pacemaker devices have been tried in treating the bradycardic aspect of NCS, no device‐based therapy exists to treat the coexistent vasodilation that occurs. The renal sympathetic innervation has been the target of denervation to treat hypertension. We hypothesized that stimulation of the renal sympathetic nerves can increase blood pressure and counteract vasodilation in NCS.

Novel balloon catheter device with pacing, ablating, electroporation, and drug-eluting capabilities for atrial fibrillation treatment--preliminary efficacy and safety studies in a canine model.

Pulmonary vein isolation is an established therapeutic procedure for symptomatic atrial fibrillation (AF). This approach involves ablation of atrial tissue just outside the pulmonary veins. However, patient outcomes are limited because of a high rate of arrhythmia recurrence. Ablation of electrically active tissue inside the pulmonary vein may improve procedural success, but is currently avoided because of the complication of postablation stenosis. An innovative device that can ablate inside pulmonary veins and prevent stenosis is a viable strategy to increase long-term efficacy. We have developed a prototypical balloon catheter device capable of nonthermal pulmonary vein ablation along with elution of an antifibrotic agent intended to eliminate arrhythmogenic substrate without the risk of stenosis and have demonstrated its functionality in 4 acute canine experiments. Further optimization of this device may provide an innovative means to simultaneously ablate and prevent pulmonary vein stenosis for improved AF treatment in humans.

Novel Percutaneous Epicardial Autonomic Modulation in the Canine for Atrial Fibrillation: Results of an Efficacy and Safety Study

Endocardial ablation of atrial ganglionated plexi (GP) has been described for treatment of atrial fibrillation (AF). Our objective in this study was to develop percutaneous epicardial GP ablation in a canine model using novel energy sources and catheters.

Novel Bloodless Potassium Determination Using a Signal‐Processed Single‐Lead ECG

Background Hyper‐ and hypokalemia are clinically silent, common in patients with renal or cardiac disease, and are life threatening. A noninvasive, unobtrusive, blood‐free method for tracking potassium would be an important clinical advance. Methods and Results Two groups of hemodialysis patients (development group, n=26; validation group, n=19) underwent high‐resolution digital ECG recordings and had 2 to 3 blood tests during dialysis. Using advanced signal processing, we developed a personalized regression model for each patient to noninvasively calculate potassium values during the second and third dialysis sessions using only the processed single‐channel ECG. In addition, by analyzing the entire development groups first‐visit data, we created a global model for all patients that was validated against subsequent sessions in the development group and in a separate validation group. This global model sought to predict potassium, based on the T wave characteristics, with no blood tests required. For the personalized model, we successfully calculated potassium values with an absolute error of 0.36±0.34 mmol/L (or 10% of the measured blood potassium). For the global model, potassium prediction was also accurate, with an absolute error of 0.44±0.47 mmol/L for the training group (or 11% of the measured blood potassium) and 0.5±0.42 for the validation set (or 12% of the measured blood potassium). Conclusions The signal‐processed ECG derived from a single lead can be used to calculate potassium values with clinically meaningful resolution using a strategy that requires no blood tests. This enables a cost‐effective, noninvasive, unobtrusive strategy for potassium assessment that can be used during remote monitoring.

Direct pulmonary vein ablation with stenosis prevention therapy

The dominant location of electrical triggers for initiating atrial fibrillation (AF) originates from the muscle sleeves inside pulmonary veins (PVs). Currently, radiofrequency ablation (RFA) is performed outside of the PVs to isolate, rather than directly ablate these tissues, due to the risk of intraluminal PV stenosis.

Advances in radiofrequency ablation of the cerebral cortex in primates using the venous system: Improvements for treating epilepsy with catheter ablation technology

BACKGROUND Pharmacology frequently fails for the treatment of epilepsy. Although surgical techniques are effective, these procedures are highly invasive. We describe feasibility and efficacy of minimally invasive mapping and ablation for the treatment of epilepsy. METHODS Mapping and radiofrequency ablations were performed via the venous system in eleven baboons and three dogs. RESULTS Mapping in deep cerebral areas was obtained in all animals. High-frequency pacing was able to induce seizure activity of local cerebral tissue in 72% of our attempts. Cerebral activity could be seen during mapping. Ablative lesions were deployed at deep brain sites without steam pops or sudden impedance rise. Histologic analysis showed necrosis at the sites of ablation in all primates. CONCLUSION Navigation through the cerebral venous system to map seizure activity is feasible. Radiofrequency energy can be delivered transvenously or transcortically to successfully ablate cortical tissue in this animal model using this innovative approach.

Compatibility of Electroanatomical Mapping Systems with a Concurrent Percutaneous Axial Flow Ventricular Assist Device

Hemodynamic instability hinders activation and entrainment mapping during ventricular tachycardia ablation. The Impella 2.5 microaxial flow device (MFD; Abiomed Inc., Danvers, MA, USA) is used to prevent hemodynamic instability during electrophysiologic study. However, electromagnetic interference (EMI) generated by this device can preclude accurate electroanatomic mapping.

Beating Heart Validation of Safety and Efficacy of a Percutaneous Pericardiotomy Tool

Epicardial procedures frequently require pericardial manipulation. We aimed to develop a nonsurgical percutaneous pericardial modification tool that may (1) facilitate epicardial‐based procedures by enabling adhesiolysis or (2) attenuate the myocardial constraining effect of the pericardium.