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BACKGROUND Ablation of complex arrhythmias would be greatly facilitated by more precise control of ablation catheters. A feasibility study was performed in animals to evaluate a novel magnetic guidance system (MGS) that generates a magnetic field to control the movement and position of a magnetic ablation catheter. METHODS AND RESULTS The MGS is composed(More)
The rapid heartbeat of ventricular tachycardia (VT) can lead to sudden cardiac death and is a major health issue worldwide. Efforts to identify patients at risk, determine mechanisms of VT, and effectively prevent and treat VT through a mechanism-based approach would all be facilitated by continuous, noninvasive imaging of the arrhythmia over the entire(More)
Heparin is thought to inhibit InsP3 binding to receptors involved in the intracellular release of Ca2+. Injection of heparin into Limulus ventral photoreceptors to high intracellular concentrations reduces the amplitude and slows the rate of rise of voltage-clamp currents induced by brief flashes, tends to make the responses to long flashes more "square,"(More)
Both slices of squid (Loligo) retinas and Limulus ventral photoreceptors, with or without prior stimulation by flashes of bright light, were rapidly frozen and analysed for cyclic-GMP content by radioimmunoassay. Measurement of the freezing process indicated that freezing occurred at about 100 msec after the light flash. No significant changes in cyclic-GMP(More)
BACKGROUND Various mechanisms of atrial fibrillation (AF) have been demonstrated experimentally. Invasive methods to study these mechanisms in humans have limitations, precluding continuous mapping of both atria with sufficient resolution. In this article, we present continuous biatrial epicardial activation sequences of AF in humans using noninvasive(More)
OBJECTIVES The purpose of this study was to determine if AV delay optimization with continuous-wave Doppler aortic velocity-time integral (VTI) is clinically superior to an empiric program in patients treated with cardiac resynchronization therapy (CRT) for severe heart failure. BACKGROUND The impact of AV delay programming on clinical outcomes associated(More)
OBJECTIVES The purpose of this study was to determine the frequency and causes of intermittent and permanent loss of cardiac resynchronization therapy (CRT) in patients who have undergone the successful implantation of a transvenous defibrillator that delivers CRT (CRT-D). BACKGROUND The causes of loss of CRT have not been described. METHODS The records(More)
INTRODUCTION Chronic kidney disease (CKD) has been independently associated with increased cardiovascular mortality. Little is known about the benefit of implantable cardioverter defibrillator (ICD) therapy for prevention of sudden death in this large, high-risk population. We sought to evaluate the impact of CKD on survival in patients who received an ICD(More)
OBJECTIVES This study aimed to identify an early marker of functional impairment after an implantable cardioverter-defibrillator (ICD) shock as a predictor of heart failure progression. BACKGROUND The ICD population has substantial risk of death due to progressive pump failure. METHODS Near-field (NF) bipolar right ventricular (RV) electrograms (EGMs)(More)