Presentation on theme: "Understanding Cardiac Electrophysiology"— Presentation transcript:
1 Understanding Cardiac Electrophysiology BY NICOLE BROOKER
2 TABLE OF CONTENTS Electrical conduction system Electrical conduction pathwayConduction components:The sinoatrial node (SA)Bachmann’s bundleInternodal tractsAtrioventricular node (AV)Right and Left Bundle branchesPerkinje fibersVentriclesBasic electrocardiograph (EKG) waveform:P wavePR intervalQRS complexST segmentT waveQT interval
3 Electrical Conduction System of the Heart The heart is supplied with an electrical conduction system that generates and conducts electrical impulses along specialized pathwaysContraction is sequence specific so the atria contracts before the ventricle and the ventricle contracts from apex to base for efficient ejection of blood.
5 CONDUCTION COMPONENTS Sinoatrial (SA) nodeInteratrial tract (Bachmann’s bundle)Internodal tracts, the atrioventricular (AV) nodeBundle of HisRight and left bundle branchesPurkinje fibers.
6 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.
7 BACHMANN’S BUNDLE INTERNODAL 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.
8 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 function 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 the ventricles, protecting them from dangerously fast rates.
9 RT AND LT BUNDLE BRANCHES From the AV node, the electrical impulse moves rapidly through the bundle of His and to the R bundle branch (R ventricle) and L bundle branch ( L ventricle).
10 PURKINJE FIBERSThe impulse then enters the Purkinje system where Purkinje fibers conduct the impulse to myocardial cells of the ventricle, causing ventricular depolarization and contraction.
11 THE VENTRICLESThe ventricles also have pacemaker cells (30 to 40 beats) that take over if impulses are not being transmitted by the SA or AV nodes.Repolarization follows.
12 Basic ECG WaveformThe heart’s electrical activity is represented by an ECG tracing by three basic waveforms: the P wave, the QRS complex, and the T wave.
13 BASIC ECG WAVEFORMBetween the waveforms are the following segments and intervals: the PR interval, the ST segment, and the QT interval. A U wave is sometimes present.
14 THE P WAVEP wave - atrial depolarization, or the spread of the impulse from the SA node throughout the atria.
15 THE PR INTERVALPR interval - the time required for the impulse to leave the SA node, travel through the atria, AV node, bundle of His, bundle branches, and Purkinje fibers.
16 THE QRS COMPLEXQRS Complex-represents ventricular depolarization and is represented by three waves: Q, R and S.
17 THE T WAVET wave - the latter phase of ventricular repolarization, and the vulnerable period of repolarization (R on T phenomenon).
18 THE ST SEGMENTST segment - represents the end of ventricular depolarization and the beginning of ventricular repolarization.
19 THE QT INTERVALQT interval - the time between the onset of ventricular depolarization and the end of ventricular repolarizationIncludes the QRS complex, ST segment, and T wave