ACLS Cardiac Rhythms & ECG Interpretation Flashcards

On a monitor strip, you see regular, wide QRS complexes at 180 bpm with no discernible P waves and the patient has a pulse. What is the most likely rhythm?

Answer: Ventricular tachycardia (VT) with pulse

Regular wide-complex tachycardia at 180 bpm with a pulse is treated as ventricular tachycardia until proven otherwise.

Which ECG feature best differentiates a junctional rhythm from a sinus rhythm?

Answer: Absent, inverted, or retrograde P waves

Junctional rhythms originate in the AV node and produce absent, inverted, or retrograde P waves because atrial activation is not antegrade.

A patient in cardiac arrest has no rhythm visible on the monitor (flat line). After confirming lead connections and gain, what is the appropriate ACLS action?

Answer: Continue high-quality CPR and administer epinephrine

Asystole is a non-shockable rhythm; management is high-quality CPR, epinephrine every 3–5 minutes, and investigation of reversible causes.

Which ECG pattern is associated with hyperkalemia and should prompt immediate intervention?

Answer: Peaked (tall, narrow) T waves, widened QRS, flattened P waves

Hyperkalemia produces peaked T waves early, then PR prolongation, P wave flattening, wide QRS, and ultimately a sine-wave pattern that can degenerate into VF.

A narrow-complex tachycardia at 160 bpm begins and terminates abruptly. Which rhythm does this pattern best describe?

Answer: Paroxysmal supraventricular tachycardia (PSVT)

PSVT (most commonly AVNRT) characteristically starts and stops abruptly, producing a regular narrow-complex tachycardia.

In third-degree (complete) AV block, what is the relationship between P waves and QRS complexes?

Answer: Complete dissociation — P waves and QRS complexes are independent

In complete heart block, the atria and ventricles are paced by independent pacemakers with no relationship between P waves and QRS complexes.