EKG certification Certification EKG Electrode Placement & Lead Systems 1 — Questions and Answers
Question 1: When placing precordial leads for a 12-lead EKG, where is the V1 electrode positioned?
- Fourth intercostal space, left sternal border
- Fourth intercostal space, right sternal border (Correct answer)
- Fifth intercostal space, midclavicular line
- Second intercostal space, right sternal border
Correct answer: Fourth intercostal space, right sternal border
V1 is placed at the fourth intercostal space along the RIGHT sternal border. V2 mirrors it on the left sternal border. This pair straddles the sternum and provides a septal view of the heart.
Question 2: Which precordial leads are classified as the lateral leads on a standard 12-lead EKG?
- V1 and V2
- V3 and V4
- V5 and V6 (Correct answer)
- V4 and V5
Correct answer: V5 and V6
V5 and V6 are the lateral precordial leads. Together with leads I and aVL (limb lateral leads), they provide a view of the lateral wall of the left ventricle.
Question 3: Where is the V6 electrode correctly placed during a 12-lead EKG?
- Anterior axillary line at the fifth intercostal space
- Midaxillary line at the fifth intercostal space (Correct answer)
- Posterior axillary line at the fourth intercostal space
- Midclavicular line at the fifth intercostal space
Correct answer: Midaxillary line at the fifth intercostal space
V6 is placed at the midaxillary line, level with V4 and V5 horizontally. This position captures electrical activity from the lateral left ventricular wall.
Question 4: In a standard 12-lead EKG, which lead is formed by the combination of leads I and III and does NOT require a separate electrode?
- aVR
- aVL
- aVF (Correct answer)
- Lead II
Correct answer: aVF
aVF is an augmented unipolar limb lead derived from the left foot electrode, with the positive pole at the left foot and the reference formed by combining the right arm and left arm electrodes. It views the heart from an inferior perspective and requires no extra electrode.
Question 5: A technician places the right leg electrode during a 12-lead EKG. What is the primary function of this electrode?
- It records the inferior wall of the heart
- It serves as the positive pole for Lead II
- It acts as an electrical ground to reduce interference (Correct answer)
- It creates the reference point for aVF
Correct answer: It acts as an electrical ground to reduce interference
The right leg (RL) electrode serves as the electrical ground for the entire recording. It does not contribute to any of the 12 leads but helps minimize electrical interference and artifact in the tracing.
Question 6: Which group of leads on a 12-lead EKG is best used to detect ischemia or injury to the anterior wall of the left ventricle?
- II, III, and aVF
- I, aVL, V5, and V6
- V1, V2, V3, and V4 (Correct answer)
- aVR and V1
Correct answer: V1, V2, V3, and V4
Leads V1 through V4 overlie the anterior surface of the heart and are therefore the primary leads for detecting anterior wall ischemia, injury, or infarction. Changes such as ST elevation or T-wave inversion in these leads point to anterior wall involvement.
EKG certification Certification EKG Electrode Placement & Lead Systems 1
When placing precordial leads for a 12-lead EKG, where is the V1 electrode positioned?