Cardiac Conduction System
• Sinoatrial node o Electrical impulses 60-100 beats/min o P wave on ECG • Atrioventricular junction o PR segment on ECG o Contraction known as “atrial kick” • Bundle of His o Right bundle branch system o Left bundle branch system Electrocardiographic Waveforms ECG Complexes, Segments, & Intervals • P wave-is a deflection representing atrial depolarization
• PR segment- is the isoelectric line from the end of the p wave to the beginning of the QRS complex • PR interval- is measured from the beginning of the P wave to the end of the PR segment • QRS complex- represents ventricular depolarization • QRS duration-represents the time required for depolarizations of both ventricles • ST segment- is normally an isoelectric line and represents early ventricular repolarization • T wave- follows the ST segment and represents ventricular repolarization • U wave- when present, follows the T wave and may result from slow repolarization of ventricular Purkinje fibers • QT interval- Represents the total time required for ventricular depolarization and repolarization Normal ECG
Determining Heart Rate ECG Rhythm Analysis • Determine heart rate • Determine heart rhythm • Analyze P waves • Measure PR interval • Measure QRS duration • Interpret rhythm Normal Sinus Rhythm Rate: 60-100 beats/min • Rhythm: Regular • P waves: Present, consistent configuration, one P wave before each QRS complex • PR interval: 0.12-0.20 second and constant • QRS duration: 0.04-0.10 second and constant
You've reached the end of your free preview.
Want to read all 4 pages?
- Spring '18
- Cardiac electrophysiology, Electrical conduction system of the heart, PR interval, Bundle of His, ventricular muscle cells, PR segment