Chapter 13 Cardio Exam With Complete Solution

Chapter 13 Cardio The electrocardiogram (ECG)- - Is a graphic representation of the electrical activity of the heart's conductive system recorded over a period of time. ECG is also used to monitor a hearts response to therapeutic interventions. THE Standard 12 Lead ECG System - 6 limb electrodes (standard 4) 6 precordial (chest) electrodes Each lead: 1. Views the electrical activity of the heart from different angles 2. Has a positive and negative component 3. Monitors specific portions of the heart from the point of view of the positive electrode in that lead. 6 Standard Limb Leads: electrodes attached to arms and legs - Lead I, II, III, aVR,(right arm) aVL,(left arm) aVF (left leg) 1. How many electrodes are used in a 12 lead ECG? - 10 electrodes. A 12 lead ECG uses 4 limb and 6 chest electrodes for a total of 10 electrodes. Which limb leads are unipolar leads? - aVR, aVL, and aVF. "a" means augmentation (V1, V2, V3 are bipolar leads and the most common) What is the name of imaginary equilateral triangle formed by the axes of the limb leads? - Einthoven's Triangle. What waveform is recorded on an ECG tracing when an electrical impulse travels perpendicular to the lead axis? - Equiphasic or a straight line would be recorded on the ECG When electrical impulses travel away from the positive electrode, what would be recorded on the ECG tracing? - Negative deflection. When electrical impulses travel toward the positive electrode, what waveform would be recorded on the ECG tracing? - Positive deflection. What does the "a" represent in the unipolar limb leads? - Augmentation 6 Limb leads monitor what? - Monitor the electrical activity in the frontal plane of the heart 6 Precordial (chest) leads monitor what? - Monitor the heart from the horizontal plane which means they record electrical activity that transverses the heart. Which limb leads are considered to be the left lateral leads? - V1 and aVL.(left arm)