ECG ECG in Clinical Practice 2 — Questions and Answers
Question 1: A patient presents with chest pain and the ECG shows ST-segment elevation in leads II, III, and aVF. Which coronary artery is most likely involved?
- Right coronary artery (Correct answer)
- Left anterior descending artery
- Left circumflex artery
- Left main artery
Correct answer: Right coronary artery
Leads II, III, and aVF represent the inferior wall, which is most commonly supplied by the right coronary artery.
Question 2: When performing a 12-lead ECG, where should the V1 electrode be placed?
- Fourth intercostal space, right sternal border (Correct answer)
- Fourth intercostal space, left sternal border
- Fifth intercostal space, midclavicular line
- Second intercostal space, right sternal border
Correct answer: Fourth intercostal space, right sternal border
V1 is placed in the fourth intercostal space at the right sternal border.
Question 3: A technician notices a wandering baseline on the ECG tracing. What is the most likely cause?
- Patient movement or respiration (Correct answer)
- Electrical interference from equipment
- Reversed limb leads
- Low battery in the machine
Correct answer: Patient movement or respiration
A slow, undulating (wandering) baseline is typically caused by patient movement or breathing.
Question 4: Which of the following best describes atrial fibrillation on an ECG?
- Irregularly irregular rhythm with no distinct P waves (Correct answer)
- Regular rhythm with sawtooth waves
- Regular rhythm with widened QRS
- Regular rhythm with prolonged PR interval
Correct answer: Irregularly irregular rhythm with no distinct P waves
Atrial fibrillation shows an irregularly irregular ventricular response with absent discrete P waves.
Question 5: What is the standard paper speed for a routine ECG recording?
- 25 mm/second (Correct answer)
- 10 mm/second
- 50 mm/second
- 5 mm/second
Correct answer: 25 mm/second
The standard ECG paper speed is 25 mm per second.
Question 6: A tall, tented T wave is most classically associated with which electrolyte abnormality?
- Hyperkalemia (Correct answer)
- Hypokalemia
- Hypercalcemia
- Hyponatremia
Correct answer: Hyperkalemia
Peaked, tented T waves are a hallmark early sign of hyperkalemia.
Question 7: Before applying electrodes, why is it important to properly prepare the patient's skin?
- To reduce impedance and improve signal quality (Correct answer)
- To speed up the heart rate
- To reduce the paper speed needed
- To increase the voltage output of the machine
Correct answer: To reduce impedance and improve signal quality
Skin prep reduces electrical impedance, improving electrode contact and tracing quality.
ECG ECG in Clinical Practice 2
A patient presents with chest pain and the ECG shows ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely involved?