Novel cardiac CT method for identifying the atrioventricular conduction axis by anatomic landmarks.

Background: Understanding the conduction axis location aids in avoiding iatrogenic damage and guiding targeted heart rhythm therapy.

Objective: Cardiac structures visible with clinical imaging have been demonstrated to correlate with variability in the conduction system course. We aimed to standardize and assess the reproducibility of predicting the location of the atrioventricular conduction axis by cardiac computed tomography.

High-resolution, real-time, and nonfluoroscopic 3-dimensional cardiac imaging and catheter navigation in humans using a novel dielectric-based system.

Background: Catheter navigation and 3-dimensional (3D) cardiac mapping are essential components of minimally invasive electrophysiological procedures.

Objective: The purpose of this study was to develop a novel 3D mapping system (KODEX - EPD, EPD Solutions, Best, The Netherlands) that measures changing electric field gradients induced on intracardiac electrodes to enable catheter localization and real-time 3D cardiac mapping.

Methods: We first validated the accuracy of the system's measurement and localization capabilities by comparing known and KODEX - EPD-measured distances and locations at 12 anatomical landmarks in both the atria and ventricles of 4 swine.

Improvement of long-term survival by cardiac contractility modulation in heart failure patients: A case-control study.

Introduction: Cardiac contractility modulation (CCM) has been shown to be effective in improving symptoms and cardiac function in heart failure (HF). However, there is limited data on the role of CCM on long-term survival, which was explored in the present study.

Methodology: Forty-one consecutive HF patients with left ventricular ejection fraction (EF) <40% received CCM and were followed for approximately 6 years.

High-speed myocardial perfusion imaging initial clinical comparison with conventional dual detector anger camera imaging.

Objectives: The purpose of this study was to compare myocardial perfusion imaging (MPI) with high-speed single-photon emission computed tomography (SPECT) with conventional SPECT imaging for the evaluation of myocardial perfusion in patients with known or suspected coronary artery disease.

Background: A novel technology has been developed for high-speed SPECT MPI by employing a bank of independently controlled detector columns with large-hole tungsten collimators and multiple cadmium zinc telluride crystal arrays.

Methods: A total of 44 patients (39 men) underwent same-day Tc-99m sestamibi stress/rest MPI.

Therapy with cardiac contractility modulation electrical signals improves left ventricular function and remodeling in dogs with chronic heart failure.

Objectives: This study examined the effects of long-term delivery of cardiac contractility modulation (CCM) electric signals on left ventricular (LV) function and global, cellular, and molecular remodeling in dogs with chronic heart failure (HF).

Background: Acute studies in dogs with experimentally induced HF showed that CCM signals applied to the failing myocardium during the absolute refractory period improved LV function without increasing myocardial oxygen consumption.

Methods: In one study, dogs with intracoronary microembolization-induced HF were randomized to 3 months of active CCM monotherapy or to a sham-operated control group.

Cardiac contractility modulation by non-excitatory currents: studies in isolated cardiac muscle.

Background: Myocardial contractility can be altered using voltage clamp techniques by modulating amplitude and duration of the action potential resulting in enhanced calcium entry in the cell of isolated muscle strips (Non-Excitatory Currents; NEC). Extracellular electrical stimuli delivered during the absolute refractory period (Cardiac Contractility Modulation; CCM) have recently been shown to produce inotropic effects in-vivo.

Aim: Understanding the cellular mechanism, underlying the CCM effect, is essential for evaluating its clinical potential.

Ventricular mapping during atrial and right ventricular pacing: relation of electrogram parameters to ventricular tachycardia reentry circuits after myocardial infarction.

Introduction: Ventricular tachycardia (VT) late after myocardial infarction is usually due to reentry in the border zone of the infarct area. Identification of critical parts of the VT reentry circuit by catheter mapping without needing to induce VT is a desirable goal for VT ablation. The aim of this study was to develop a model to predict reentry circuit locations based on characteristics of sinus or paced electrograms and pace mapping (PM) recorded from the infarct region.

Use of novel nonfluoroscopic three-dimensional electroanatomic mapping system to monitor and analyze heart surgery in animal models.

Background: The new method of three-dimensional (3D) electroanatomic mapping was presented as an important tool for cardiac imaging and intervention. We present herein the first use of this technology for the monitoring, analysis, and development of cardiac surgery at the preclinical stage.

Methods: The method is based on utilizing a locatable catheter connected to an endocardial mapping and navigating system, to accurately establish the location and orientation of the tip of the mapping catheter and simultaneously record its local electrogram.

First human chronic experience with cardiac contractility modulation by nonexcitatory electrical currents for treating systolic heart failure: mid-term safety and efficacy results from a multicenter study.

Introduction: Conventional electrical therapies for heart failure (HF) encompass defibrillation and ventricular resynchronization for patients at high risk for lethal arrhythmias and/or with inhomogeneous ventricular contraction. Cardiac contractility modulation (CCM) by means of nonexcitatory electrical currents delivered during the action potential plateau has been shown to acutely enhance systolic function in humans with HF. The aim of this multicenter study was to assess the chronic safety and preliminary efficacy of an implantable device delivering this novel form of electrical therapy.

Chronic electrical stimulation during the absolute refractory period of the myocardium improves severe heart failure.

Aim: In experimental studies, nonexcitatory electrical stimulation delivered at the time of absolute myocardial refractoriness resulted in cardiac contractility modulation (CCM) with improved systolic function. This study reports the initial experience with CCM in patients with chronic heart failure.

Methods And Results: Twenty-five patients, 23 males, with a mean age of 62+/-9 years and drug-refractory NYHA class III heart failure were assigned to CCM-generator implantation.

Long-term effects of non-excitatory cardiac contractility modulation electric signals on the progression of heart failure in dogs.

Objective: We previously showed that acute delivery of non-excitatory cardiac contractility modulation (CCM) electric signal during the absolute refractory period improved LV function in dogs with chronic heart failure (HF). In the present study we examined the long-term effects of CCM signal delivery on the progression of LV dysfunction and remodeling in dogs with chronic HF.

Methods: Chronic HF was produced in 12 dogs by multiple sequential intracoronary microembolizations.

Enhancement of antral contractions and vagal afferent signaling with synchronized electrical stimulation.

Gastric filling activates vagal afferents involved in peripheral signaling to the central nervous system (CNS) for food intake. It is not known whether these afferents linearly encode increasing contractions of the antrum during antral distension (AD). The aim of this study was to investigate effects of AD and electrically enhanced antral contractions on responses of vagal afferents innervating the antrum.

Relationship of slow conduction detected by pace-mapping to ventricular tachycardia re-entry circuit sites after infarction.

Objectives: This study sought to characterize the relationship of conduction delays detected by pace-mapping, evident as a stimulus to QRS interval (S-QRS) delay >or=40 ms, to ventricular tachycardia (VT) re-entry circuit isthmuses defined by entrainment and ablation.

Background: Areas of slow conduction and block in old infarcts cause re-entrant VT.

Methods: In 12 patients with VT after infarction, pace-mapping was performed at 890 sites.

Cardiac contractility modulation with nonexcitatory electric signals improves left ventricular function in dogs with chronic heart failure.

Background: Nonexcitatory electrical, signals termed cardiac contractility modulation (CCM) have been shown to improve contractile force of isolated papillary muscles. In this study, we examined the effects of CCM signal delivery on left ventricular function in dogs with chronic heart failure (HF).

Methods And Results: Chronic HF (ejection fraction View Article and Find Full Text PDF

Temporal changes in the endocardial ST segment during the evolution of myocardial infarction in dogs.

Acute coronary occlusion causes ST-segment elevation on the body surface ECG and on the epicardial electrogram in the territory supplied by that artery. The occurrence and significance of endocardial ST changes have not been studied. The NOGA electromechanical mapping was performed on eight anesthetized dogs at baseline, immediately after occlusion of the LAD, and again at 5 hours to assess regional changes in the ST segment.

Cardiac contractility modulation by electric currents applied during the refractory period in patients with heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

We assessed the feasibility of cardiac contractility modulation (CCM) by electric currents applied during the refractory period in patients with heart failure (HF). Extracellular electric currents modulating action potential and calcium transients have been shown to potentiate myocardial contractility in vitro and in animal models of chronic HF. CCM signals were biphasic square-wave pulses with adjustable amplitude, duration, and time delay from sensing of local electric activity.

Electric currents applied during refractory period enhance contractility and systolic calcium in the ferret heart.

We investigated the mechanism of positive inotropism of electric currents applied during the absolute refractory period. Ten Langendorff-perfused ferret hearts were instrumented to measure isovolumic left ventricular pressure (LVP) and the aequorin luminescence. Biphasic square-wave electric currents (+/-20 mA, total duration 30 ms) were delivered between pairs of electrodes.

Technical delivery of myogenic cells through an endocardial injection catheter for myocardial cell implantation.

BACKGROUND: The next clinical frontier in the therapeutics of ischemic heart disease may involve the development and delivery of specific molecules and cells into the myocardium. The aim of the present study was to evaluate the efficiency and safety of the MyoStar injection catheter (Biosense-Webster Inc.) that has recently been developed to deliver molecules and cells to the myocardium.

Evaluation of inotropic changes in ventricular function by NOGA mapping: comparison with echocardiography.

Assessment of left ventricular (LV) function in the catheterization laboratory is important to optimize treatment decisions and guide catheter-based local therapies. NOGA electromechanical mapping was developed to assess LV contraction during catheterization; however, quantitative analysis of its "local shortening" (LS) algorithm and direct comparison with conventional methods are lacking. We evaluated the accuracy of NOGA-based regional and global function by examining its ability to detect pharmacologically induced changes in contractility compared with echocardiography.

Cardiac contractility modulation by electric currents applied during the refractory period.

Inotropic effects of electric currents applied during the refractory period have been reported in cardiac muscle in vitro using voltage-clamp techniques. We investigated how electric currents modulate cardiac contractility in normal canine hearts in vivo. Six dogs were instrumented to measure regional segment length, ventricular volume (sonomicrometry), and ventricular pressure.