tailieunhanh - Essential Cardiac Electrophysiology Self Assessment - Part 4

Các đặc điểm của các cơ chế khác nhau của đầu mối AT tự động AT isoproterenol PES cho cuốn theo cảm ứng ấm lên mát mẻ xuống đáp ứng adenosine đáp ứng propranolol, verapamil diễn tập phế vị không có phản hồi | 78 Essential Cardiac Electrophysiology Atrial tachycardia AT Focal AT Nonautomatic Automatic Macroreentrant AT Mechanisms Reentry Triggered activity Microreentry Fig Classification of atrial Isthmus dependent Non-isthmus dependent Table Characteristics of the different mechanisms of focal AT Automatic AT Triggered activity Microreentrant AT PES No response CL dependent Reproducibly initiates and terminates AT Isoproterenol for induction Yes No No Entrainment No No Yes Warm up cool down Yes No No Response to adenosine No Yes Yes Response to propranolol verapamil Propranolol Propranolol verapamil Verapamil Vagal maneuvers No response Terminates AT No response PES programmed electrical stimulation. Yes if AT is induced by Isoproterenol. Major drawback of the above observations is the overlap of responses. Electrophysiologic mechanism of the atrial tachycardia can be reentry abnormal automaticity or triggered activity Table . Focal tachycardias are characterized by centrifugal spread of electrical impulse from a single focus. Activation covers less than 20 of the tachycardia cycle length CL . Localization of the focal AT can be achieved by multielectrode catheters or point-to-point exploration of the atrium after regionalizing the focus. Some focal AT origin sites may produce misleading activation results. These sites include the following 1 Right superior pulmonary vein RSPV focus could be mistaken for superior right atrium RA . 2 Superior vena cava SVC focus may be mistaken for right AT. 3 Focal AT arising from the left-hand side of the interatrial septum. 4 Epicardial focus and Marshall s ligament. Tachycardia arising from these sites may be difficult to ablate due to epicardial origin and can be mistaken for tachycardia arising from the left pulmonary vein or atrial appendage. Supraventricular Tachycardia 79 Pos P wave in LII LIII aVF Neg P wave in LI aVL Pos P 80 msec in V1 Superolateral RA RSPV Laterak LA LSPV LIPV Neg P wave in LII .