Life-Threatening Arrhythmias Flashcards

Which electrolyte abnormality is most directly associated with development of torsades de pointes?

Answer: Hypomagnesemia

Hypomagnesemia is a major risk factor for torsades de pointes and IV magnesium sulfate is the specific treatment, even if serum magnesium levels appear near normal.

In the chain of survival, early defibrillation for VF is critical because VF survival decreases by approximately how much for each minute without defibrillation?

Answer: 7-10% per minute

Without defibrillation, survival rates for VF decrease 7-10% for every minute that passes, making rapid defibrillation the most critical intervention after cardiac arrest.

Accelerated idioventricular rhythm (AIVR) most commonly occurs in which clinical setting?

Answer: Reperfusion after myocardial infarction

AIVR is a classic reperfusion arrhythmia seen within hours of restoring coronary flow after MI (thrombolytics or PCI), generally considered benign and self-limiting.

Hyperkalemia classically produces which ECG change that can progress to ventricular fibrillation?

Answer: Progressive widening of QRS followed by sine-wave pattern

Hyperkalemia produces sequential ECG changes: peaked T waves → PR prolongation → P wave flattening → QRS widening → sine-wave pattern → VF/asystole.

When defibrillating a patient, which safety precaution is most critical immediately before delivering the shock?

Answer: Ensure all personnel are clear of the patient and bed before discharging

Clearing all personnel from the patient and bed is the most critical safety step — delivering the shock while anyone is in contact risks severe electrical injury to bystanders.

A patient's ECG shows wide complex tachycardia at 180 bpm. Which feature most strongly supports a ventricular rather than supraventricular origin?

Answer: AV dissociation with P waves marching independently through QRS complexes

AV dissociation — independent P wave and QRS activity with no relationship between them — is the most specific ECG finding confirming ventricular tachycardia.