Understanding Cardiac Electrophysiology and Arrhythmias了解心脏电生理及心律失常.ppt

BY NICOLE BROOKER TABLE OF CONTENTS Electrical conduction system Electrical conduction pathway Conduction components: The sinoatrial node (SA) Bachmann’s bundle Internodal tracts Atrioventricular node (AV) Right and Left Bundle branches Perkinje fibers Ventricles Basic electrocardiograph (EKG) waveform: P wave PR interval QRS complex ST segment T wave QT interval Electrical Conduction System of the Heart The heart is supplied with an electrical conduction system that generates and conducts electrical impulses along specialized pathways Contraction is sequence specific so the atria contracts before the ventricle and the ventricle contracts from apex to base for efficient ejection of blood. ELECTRICAL CONDUCTION PATHWAY CONDUCTION COMPONENTS Sinoatrial (SA) node Interatrial tract (Bachmann’s bundle) Internodal tracts, the atrioventricular (AV) node Bundle of His Right and left bundle branches Purkinje fibers. THE SINOATRIAL NODE (SA) The SA node, located in the upper right atrium, is the primary pacemaker of the heart (60 to 100 beats). If the SA node fails to generate impulses or if those impulses are blocked, pacemaker cells in other sites can assume control, but at a slower rate. BACHMANN’S BUNDLEINTERNODAL TRACTS Bachmann’s bundle conducts impulses to the left atrium, while the internodal tracts conduct impulses to the AV node, located in the lower R atrium near the interatrial septum. ATRIOVENTRICULAR NODE Primary function-slow conduction of electrical impulses coming from the atria, allowing time for the atria to contract and empty their contents into the ventricles. It can functions as a backup pacemaker (40 to 60 beats). When the atrial rate is rapid, the AV node blocks some of the impulses being conducted to th