Ralph Lazzara

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BACKGROUND It is thought that only a thin layer of tissue adjacent to the electrode is heated directly by electrical current (resistive heating) during radiofrequency ablation. Most of the thermal injury is thought to result from conduction of heat from the surface layer. The purpose of this study was to determine whether lesion depth could be increased by(More)
The congenital long-QT syndrome (LQTS) is characterized by prolonged QT intervals, QT interval lability, and polymorphic ventricular tachycardia. The manifestations of the disease vary, with a high incidence of sudden death in some affected families but not in others. Mutations causing LQTS have been identified in three genes, each encoding a cardiac ion(More)
BACKGROUND An open-irrigated radiofrequency (RF) ablation catheter was developed to measure contact force (CF). Three optical fibers measure microdeformation of the catheter tip. The purpose of this study was to (1) validate the accuracy of CF sensor (CFS) (bench test); and (2) determine the relationship between CF and tissue temperatures, lesion size,(More)
Coronary artery aneurysms were found in 16 men between 37 and 62 years of age, mean 51 years. Aneurysms were of two types: saccular and fusiform. They involved the right coronary artery in 13 (87 per cent), the circumflex artery in eight (50 per cent) and the left anterior descending artery in five (31 per cent). In some patients, more than one vessel was(More)
BACKGROUND Rapid firing within pulmonary vein sleeves frequently initiates atrial fibrillation. The role of the autonomic nervous system in facilitating spontaneous firing is unknown. OBJECTIVES The purpose of this study was to determine if autonomic nerve stimulation within canine atrium and pulmonary vein sleeves initiates arrhythmia formation. (More)
BACKGROUND Heart rate variability (HRV) is typically higher during nighttime. This evidence supports the concept that overall, sleep is a condition during which vagal activity is dominant. Myocardial infarction (MI) results in a loss in the overall nocturnal HRV increase. However, the characteristics of HRV during specific sleep stages in normal subjects(More)
BACKGROUND The purpose of this study was to characterize the circuit of macroreentrant right atrial tachycardia (MacroAT) in patients after surgical repair of congenital heart disease (SR-CHD). METHODS AND RESULTS Sixteen patients with atrial tachycardia (AT) after SR-CHD were studied (atrial septal defect in 6, tetralogy of Fallot in 4, and Fontan(More)
a , a b c a * Paul G.A. Volders , Marc A. Vos , Bela Szabo , Karin R. Sipido , S.H. Marieke de Groot , a a b Anton P.M. Gorgels , Hein J.J. Wellens , Ralph Lazzara Department of Cardiology, Cardiovascular Research Institute Maastricht, Academic Hospital Maastricht, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands Department of Medicine, Cardiovascular(More)
BACKGROUND Vagal stimulation shortens the atrial effective refractory period (AERP) and maintains atrial fibrillation (AF). This study investigated whether the parasympathetic pathways that innervate the atria can be identified and ablated by use of transvenous catheter stimulation and radiofrequency current catheter ablation (RFCA) techniques. METHODS(More)