Introduction The electrocardiogram (ECG) records the flow of electrical impulses throughout the heart Electrical currents flow from negatively charged areas to positively charged areas depolarization currents flowing towards a positive electrode will lead to an upward deflection seen in the ECG reading repolarization currents flowing away from the positive electrode will lead to a downward deflection seen in the ECG reading the ECG records the sum of the electrical forces that flow through the heart the ECG deflections depend on how these electrical forces align to a specific ECG lead e.g., lead aVR, a right-arm electrode, will demonstrate a positive deflection when electrical activity points towards the right arm C1: Snapshot: Y C2: Content/grammar: Y C3: Images/Videos: N C4: Questions: Y C5: References: N ECG Lead Reference There are 6 limb leads and 6 chest lead, which comprise the 12-lead ECG limb leads aVR, aVL, and aVF I, II, III the limb leads read electrical forces in the frontal view chest (precordial) leads V1-V6 the precordial leads read electrical forces in the perpendicular plane Conduction Pathway Depolarization normally begins at the sinoatrial (SA) node the SA node is located at the junction of the superior vena cava and right atrium Depolarization from the SA node spreads to the right and left atria After the right and left atria, the wave of depolarization reaches the atrioventricular (AV) node there is an expected delay in the transmission of depolarization to the ventricles at the AV node The impulse then goes to the bundle of His and then the right and left Purkinje fibers Pacemaker rates SA > AV > bundle of His/Purkinje/ventricles Speed of transmission bundle of His = Purkinje fibers > atria > ventricles > AV node ECG And Conduction Pathway ECG BasicsECG FindingInformationP waveRepresents atrial depolarizationPR intervalRepresents the time from the start of atrial depolarization to the start of ventricular depolarizationNormally < 200 msecQRS complexRepresents ventricular depolarizationNormally < 120 msecST segmentRepresents an isoelectric point in ventricular depolarizationCorrelates with phase 2 (plateau) of ventricular action potentialT waveRepresents ventricular repolarizationBecomes peaked in hyperkalemia and flattened in hypokalemiaU waveBelieved to represent ventricular repolarization but during the late phaseBecomes prominent in hypokalemiaJ pointThe point between the end of the QRS complex and the beginning of the ST segment
QUESTIONS 1 of 4 1 2 3 4 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK
All Videos (1) Login to View Community Videos Login to View Community Videos Cardiac Conduction system Cardiovascular - Electrocardiogram (ECG) D 2/12/2015 206 views 5.0 (3) Cardiovascular | Electrocardiogram (ECG) Cardiovascular - Electrocardiogram (ECG) Listen Now 11:11 min 12/12/2022 7 plays 0.0 (0)