ACLS ACLS Cardiac Rhythm Recognition 1 — Questions and Answers
Question 1: On the cardiac monitor, which rhythm shows chaotic, irregular waveforms with no discernible P waves or QRS complexes?
- Ventricular fibrillation (VF) (Correct answer)
- Asystole
- Pulseless electrical activity (PEA)
- Atrial fibrillation with rapid ventricular response
Correct answer: Ventricular fibrillation (VF)
Ventricular fibrillation produces chaotic, disorganized electrical activity with no identifiable P waves, QRS complexes, or T waves.
Question 2: Pulseless electrical activity (PEA) is defined as:
- Any organized electrical rhythm on the monitor without a palpable pulse (Correct answer)
- Ventricular fibrillation without a palpable pulse
- Asystole with occasional P waves
- Atrial fibrillation with hemodynamic instability
Correct answer: Any organized electrical rhythm on the monitor without a palpable pulse
PEA is the presence of organized cardiac electrical activity (other than VF/VT) without a corresponding palpable pulse or effective cardiac output.
Question 3: Which of the following rhythms is NOT a shockable rhythm in the ACLS cardiac arrest algorithm?
- Asystole (Correct answer)
- Ventricular fibrillation
- Pulseless ventricular tachycardia
- Coarse ventricular fibrillation
Correct answer: Asystole
Asystole (flat line) is a non-shockable rhythm; defibrillation has no benefit when there is no electrical activity to be organized.
Question 4: A wide-complex tachycardia at 180 bpm in a patient without a pulse should be treated as:
- Pulseless ventricular tachycardia — defibrillate immediately (Correct answer)
- Supraventricular tachycardia — administer adenosine 6 mg IV
- Atrial flutter — perform synchronized cardioversion
- Sinus tachycardia — identify and treat the cause
Correct answer: Pulseless ventricular tachycardia — defibrillate immediately
Pulseless VT is a shockable cardiac arrest rhythm; immediate unsynchronized defibrillation (not synchronized cardioversion) is the treatment.
Question 5: On a 12-lead ECG, ST elevation in leads II, III, and aVF with reciprocal changes in leads I and aVL most likely indicates:
- Inferior ST-elevation myocardial infarction (STEMI) (Correct answer)
- Anterior STEMI
- Left bundle branch block
- Benign early repolarization
Correct answer: Inferior ST-elevation myocardial infarction (STEMI)
ST elevation in the inferior leads (II, III, aVF) with reciprocal depression in lateral leads indicates an inferior STEMI, typically from right coronary artery occlusion.
Question 6: What does a delta wave on an ECG indicate?
- Wolff-Parkinson-White (WPW) syndrome with ventricular pre-excitation (Correct answer)
- Complete heart block
- Right bundle branch block
- Hyperkalemia-induced conduction abnormality
Correct answer: Wolff-Parkinson-White (WPW) syndrome with ventricular pre-excitation
A delta wave — a slurred upstroke at the beginning of the QRS — is the hallmark of WPW syndrome caused by an accessory pathway that pre-excites the ventricles.
ACLS ACLS Cardiac Rhythm Recognition 1
On the cardiac monitor, which rhythm shows chaotic, irregular waveforms with no discernible P waves or QRS complexes?