Represents remnants of ventricular repolarization (relaxation) Prominent U waves indicate pathological conditions affecting repolarization of ventricles Ectopic foci Abnormal pacemaker sites within heart (outside of SA node) that display automaticity leads longer QRS complex After treatment of myocardial infarction, some cells spontaneously have depolarization in ventricle tissue called ectopic foci This depolarization can send signal to other part of ventricles or even atrium In EKG, we see normal P, Q, R, and S, T, P, Abnormal QRS, then T. Post myocardial infarction appears as abnormal QRS in EKG. PR interval Depolarization of AV node AV node connects and transfers the signals from atrium to ventricle Duration should be 0.12 to 0.20 seconds Longer than 0.2 seconds shows that there is a problem in AV node and interruption between atrium and ventricle which is called AV node block or AV conduction block. AV block there is no perfect connection between atrium and ventricle ST segment Means ventricle has already had (completed) contraction and is ready for relaxation phase Clinical depressed or elevated ST segment Positive sign for myocardial infarction This means there is a problem in myocardial tissue that cannot complete normal contractility phase QT interval From start of QRS to end of T wave Show ventricular contraction and relaxation depolarization and repolarization High heart rates (tachyarrhythmias) ventricular contraction duration shortens which leads to shortened QT intervals Conduction system in heart Sinoatrial node (SA node) Location In superior vena cava Normal pacemaker of the Atrioventricular node (AV node) Located on right atrium in atrial sectum
Represents remnants of ventricular repolarization (relaxation) Prominent U waves indicate pathological conditions affecting repolarization of ventricles Ectopic foci Abnormal pacemaker sites within heart (outside of SA node) that display automaticity leads longer QRS complex After treatment of myocardial infarction, some cells spontaneously have depolarization in ventricle tissue called ectopic foci This depolarization can send signal to other part of ventricles or even atrium In EKG, we see normal P, Q, R, and S, T, P, Abnormal QRS, then T. Post myocardial infarction appears as abnormal QRS in EKG. PR interval Depolarization of AV node AV node connects and transfers the signals from atrium to ventricle Duration should be 0.12 to 0.20 seconds Longer than 0.2 seconds shows that there is a problem in AV node and interruption between atrium and ventricle which is called AV node block or AV conduction block. AV block there is no perfect connection between atrium and ventricle ST segment Means ventricle has already had (completed) contraction and is ready for relaxation phase Clinical depressed or elevated ST segment Positive sign for myocardial infarction This means there is a problem in myocardial tissue that cannot complete normal contractility phase QT interval From start of QRS to end of T wave Show ventricular contraction and relaxation depolarization and repolarization High heart rates (tachyarrhythmias) ventricular contraction duration shortens which leads to shortened QT intervals Conduction system in heart Sinoatrial node (SA node) Location In superior vena cava Normal pacemaker of the Atrioventricular node (AV node) Located on right atrium in atrial sectum
chapter-11b-part-2-cardiovascular-physiology.docx