CCI ECG Rhythm Interpretation 2 — Questions and Answers
Question 1: A patient's ECG shows a regular rhythm at 150 bpm with narrow QRS complexes and no visible P waves. Which rhythm is most likely?
- Atrial flutter with 2:1 block (Correct answer)
- Sinus tachycardia
- Ventricular tachycardia
- Accelerated junctional rhythm
Correct answer: Atrial flutter with 2:1 block
Atrial flutter typically produces a ventricular rate of 150 bpm when 2:1 AV conduction is present, often hiding flutter waves in the QRS or T wave.
Question 2: Which ECG feature best distinguishes Wolff-Parkinson-White (WPW) syndrome from a bundle branch block?
- Delta wave and short PR interval (Correct answer)
- Wide QRS and tall R wave
- ST depression in lateral leads
- Prolonged QT interval
Correct answer: Delta wave and short PR interval
WPW is characterized by a delta wave (slurred QRS upstroke) and a short PR interval (<0.12 sec) due to accessory pathway pre-excitation.
Question 3: An ECG shows regular P waves at 75 bpm, but only every other P wave conducts. The PR interval of conducted beats is constant. What is the rhythm?
- Second-degree AV block, Mobitz type II (Correct answer)
- Second-degree AV block, Mobitz type I
- Complete heart block
- First-degree AV block
Correct answer: Second-degree AV block, Mobitz type II
2:1 conduction with a constant PR interval on conducted beats and non-conducted P waves is consistent with Mobitz type II second-degree AV block.
Question 4: What is the significance of a U wave on the ECG?
- It often indicates hypokalemia when prominent (Correct answer)
- It represents atrial repolarization
- It signifies complete ventricular depolarization
- It is always pathological
Correct answer: It often indicates hypokalemia when prominent
Prominent U waves are a classic ECG sign of hypokalemia; they appear after the T wave and can mimic a prolonged QT interval.
Question 5: A patient with no pulse has an ECG showing organized electrical activity. What is this condition called?
- Pulseless electrical activity (PEA) (Correct answer)
- Ventricular fibrillation
- Asystole
- Idioventricular rhythm
Correct answer: Pulseless electrical activity (PEA)
PEA is defined as organized cardiac electrical activity on ECG without a corresponding palpable pulse, requiring CPR and treatment of reversible causes.
Question 6: On a 12-lead ECG, ST elevation in leads II, III, and aVF most likely indicates ischemia in which territory?
- Inferior wall (Correct answer)
- Anterior wall
- Lateral wall
- Posterior wall
Correct answer: Inferior wall
Leads II, III, and aVF view the inferior surface of the heart, supplied primarily by the right coronary artery.
Question 7: Which finding on ECG is characteristic of hyperkalemia?
- Tall, peaked T waves (Correct answer)
- Prolonged QT interval
- Delta waves
- Prominent U waves
Correct answer: Tall, peaked T waves
Hyperkalemia classically produces tall, narrow, peaked (tent-shaped) T waves, especially in precordial leads, as an early ECG manifestation.
CCI ECG Rhythm Interpretation 2
A patient's ECG shows a regular rhythm at 150 bpm with narrow QRS complexes and no visible P waves.
Which rhythm is most likely?