ACLS Cardiac Rhythms and ECG Interpretation Flashcards

A patient has third-degree (complete) heart block. Which ECG finding is characteristic?

Answer: P waves and QRS complexes with no relationship to each other (AV dissociation)

Complete heart block shows complete AV dissociation — P waves and QRS complexes fire independently at different rates with no consistent PR relationship.

What ECG finding is associated with hyperkalemia that warrants immediate ACLS intervention?

Answer: Peaked (tall, narrow, tent-shaped) T waves

Hyperkalemia classically produces tall, peaked, tent-shaped T waves as an early ECG sign, which can progress to wide QRS, sine wave pattern, and cardiac arrest.

In ACLS, which ECG finding is a classic sign of right ventricular strain in massive pulmonary embolism?

Answer: S1Q3T3 pattern (S wave in I, Q wave and T inversion in III)

The S1Q3T3 pattern (large S in lead I, Q wave and inverted T in lead III) is a classic ECG sign of acute right heart strain seen in massive pulmonary embolism.

Asystole on ECG appears as what pattern?

Answer: A flat (isoelectric) line with no electrical activity

Asystole appears as a flat isoelectric line on ECG, confirming the absence of any organized cardiac electrical activity.

Which ECG finding indicates Wolff-Parkinson-White (WPW) syndrome that is important in ACLS?

Answer: Short PR interval with a delta wave (slurred QRS upstroke)

WPW is identified by a short PR interval (<0.12 s) and a delta wave (slurred initial QRS deflection) caused by ventricular pre-excitation via an accessory pathway.

During ACLS, a monitor shows fine ventricular fibrillation (fine VF). What is the correct next step?

Answer: Defibrillate immediately — fine VF is still a shockable rhythm

Fine VF remains a shockable rhythm; immediate defibrillation is indicated regardless of amplitude — delaying shock worsens outcomes.