ACLS ECG Quiz
Questions: 16 · 10 minutes
1. An ECG shows regular, sawtooth atrial activity near 300 beats per minute, with every second atrial impulse conducted to the ventricles. What is the most likely rhythm?
Sinus tachycardia
Atrial fibrillation
Atrial flutter with 2:1 conduction
AV nodal re-entrant tachycardia
2. An adult has a tachyarrhythmia with a pulse and develops hypotension, confusion, and signs of shock attributable to the rhythm. What intervention is generally indicated without unnecessary delay?
Synchronized cardioversion
Unsynchronized defibrillation
Observation until the rhythm terminates spontaneously
Transcutaneous pacing
3. During apparent chaotic monitor activity, the patient is awake, has a strong pulse, and normal QRS complexes can be seen marching through the distortion in another lead. What is the best interpretation?
The patient has pulseless ventricular fibrillation
The patient has asystole interrupted by escape beats
The patient has complete heart block
Motion or electrode artifact is likely mimicking a dangerous rhythm
4. A rhythm has no consistent P waves, narrow QRS complexes, and irregularly irregular R-R intervals. Which rhythm best fits this description?
Atrial flutter with fixed conduction
Atrial fibrillation
Sinus arrhythmia
Monomorphic ventricular tachycardia
5. A patient with renal failure develops tall, narrow peaked T waves, progressive PR prolongation, and widening of the QRS complex. Which metabolic problem should be strongly suspected?
Hypokalemia
Hyperkalemia
Hypercalcemia
Respiratory alkalosis
6. The monitor displays a regular wide-complex tachycardia at 170 beats per minute. Each QRS complex has essentially the same shape. Which rhythm should be suspected?
Atrial flutter with variable conduction
Sinus tachycardia with premature atrial beats
Polymorphic ventricular tachycardia
Monomorphic ventricular tachycardia
7. A collapsed adult is unresponsive and pulseless. The monitor shows coarse ventricular fibrillation, and a defibrillator is ready. What is the appropriate electrical treatment?
Synchronized cardioversion followed by a pulse check
Withhold electrical therapy because ventricular fibrillation is non-shockable
Begin transcutaneous pacing before CPR
Deliver an unsynchronized shock, then promptly resume CPR
8. A stable patient has a regular narrow-complex tachycardia at 180 beats per minute. Vagal maneuvers do not terminate it. Which medication is commonly considered next in the ACLS tachycardia pathway?
Atropine
Adenosine
Magnesium sulfate for every narrow-complex rhythm
Epinephrine as used during cardiac arrest
9. The monitor shows organized electrical complexes at 45 beats per minute, but the patient has no palpable pulse. How should this rhythm be classified?
Sinus bradycardia
Pulseless electrical activity
Asystole
Fine ventricular fibrillation
10. A patient’s heart rate increases gradually during fever, varies modestly over time, and has a visible P wave before each narrow QRS. Which interpretation is most likely?
Ventricular tachycardia
Atrial fibrillation with rapid ventricular response
Sinus tachycardia
Paroxysmal supraventricular tachycardia
11. Why is synchronization used when cardioverting a tachyarrhythmia in a patient who still has a pulse?
It times the shock with the R wave to reduce the chance of an R-on-T event
It makes electrical energy unnecessary
It ensures that every shock is delivered during the T wave
It converts the shock into transcutaneous pacing impulses
12. An ECG shows a constant PR interval of 0.24 seconds, and every P wave is followed by a QRS complex. Which conduction pattern is present?
First-degree AV block
Second-degree AV block, Mobitz II
Third-degree AV block
Second-degree AV block, Mobitz I
13. Which ECG finding is most concerning for an acute coronary injury pattern when it appears in the appropriate clinical context?
A prolonged PR interval with every P wave conducted
An isolated premature atrial complex
New ST-segment elevation in anatomically contiguous leads
Respiratory variation in the sinus rate
14. A patient is pulseless, and two leads confirm asystole rather than fine ventricular fibrillation. Which approach is appropriate?
Deliver repeated synchronized shocks
Perform transcutaneous pacing until a pulse returns
Continue high-quality CPR, give epinephrine per protocol, and seek reversible causes
Treat the rhythm as stable bradycardia
15. A patient has symptomatic bradycardia with hypotension and altered mental status. Atropine has not improved the heart rate, and pacing equipment is immediately available. What is a reasonable next intervention?
Unsynchronized defibrillation
Synchronized cardioversion for ventricular fibrillation
Adenosine by rapid IV push
Transcutaneous pacing
16. A patient with a prolonged QT interval develops a rapid wide-complex rhythm whose QRS amplitude and axis appear to twist around the baseline. What rhythm is this?
Torsades de pointes
Monomorphic ventricular tachycardia
Ventricular fibrillation
Atrial fibrillation with rapid ventricular response