CRAT Life-Threatening Arrhythmias 2 — Questions and Answers

Question 1: Ventricular fibrillation on an ECG is best described by which appearance?

Chaotic, irregular waveforms with no discernible QRS complexes (Correct answer)
Regular wide complex tachycardia at 150-250 bpm
Fine regular oscillations at 300 bpm
Absent all electrical activity

Correct answer: Chaotic, irregular waveforms with no discernible QRS complexes

Ventricular fibrillation produces completely chaotic, irregular electrical activity with no organized QRS complexes — the ventricles quiver rather than contract effectively.

In VF, multiple chaotic re-entrant wavelets depolarize the ventricles randomly at rates of 350-600 bpm without any organized contraction. The ECG shows irregular, undulating waveforms of varying amplitude. VF produces no cardiac output and is immediately fatal without defibrillation. ACLS protocols dictate immediate unsynchronized defibrillation.

Question 2: The immediate treatment for pulseless ventricular tachycardia is which intervention?

Unsynchronized defibrillation (cardioversion) (Correct answer)
Synchronized cardioversion
IV adenosine
IV amiodarone bolus only

Correct answer: Unsynchronized defibrillation (cardioversion)

Pulseless VT is treated identically to VF with immediate unsynchronized defibrillation, as it represents a cardiac arrest requiring immediate restoration of organized rhythm.

Pulseless VT, like VF, is a shockable arrest rhythm. Unsynchronized defibrillation (360 J monophasic or 200 J biphasic) is the first-line treatment. CPR is initiated while the defibrillator charges. Synchronized cardioversion is used for VT with a pulse. The distinction matters because synchronization attempts to fire on the R wave; in pulseless VT, delay for synchronization wastes precious time.

Question 3: Torsades de pointes is a form of polymorphic VT most closely associated with which ECG finding before its onset?

Prolonged QT interval (Correct answer)
Shortened PR interval
Widened QRS complex
ST elevation

Correct answer: Prolonged QT interval

Torsades de pointes typically occurs in the setting of a prolonged QT interval, which indicates prolonged ventricular repolarization and increased risk of early afterdepolarizations.

Torsades de pointes (TdP) is triggered by early afterdepolarizations during prolonged repolarization. It appears as a polymorphic VT where QRS complexes appear to twist around the baseline. Causes of long QT include electrolyte disturbances (hypokalemia, hypomagnesemia), medications (quinidine, sotalol, haloperidol, some antibiotics), and congenital long QT syndrome. IV magnesium is the treatment of choice.

Question 4: Asystole on the cardiac monitor is confirmed by which finding?

Flat line in at least two leads with confirmed electrode placement (Correct answer)
Flat line in only one lead
Heart rate of zero with normal waveforms
Absent P waves only

Correct answer: Flat line in at least two leads with confirmed electrode placement

True asystole must be confirmed in at least two leads to rule out artifact or a disconnected electrode causing a false flat line — always check multiple leads before treating as asystole.

Before declaring asystole and initiating non-shockable ACLS protocol, verify the flat line in more than one lead (minimum two). Check electrode connections, increase gain, and assess the patient. Fine VF can sometimes masquerade as asystole; if in doubt, defibrillate. The ACLS non-shockable algorithm for asystole/PEA uses high-quality CPR and epinephrine.

Question 5: Pulseless electrical activity (PEA) is defined by which combination of findings?

Organized ECG rhythm with no detectable pulse (Correct answer)
No ECG activity and no pulse
Regular ECG rhythm with a strong palpable pulse
Ventricular fibrillation without a pulse

Correct answer: Organized ECG rhythm with no detectable pulse

PEA is the presence of organized electrical activity on the ECG (excluding VT/VF) with no palpable pulse — the heart generates electrical signals but fails to produce effective mechanical contraction.

PEA (formerly called electromechanical dissociation) has many reversible causes captured by the Hs and Ts: Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo/Hyperkalemia, Hypothermia, Tension pneumothorax, Tamponade, Toxins, Thrombosis (PE/MI). Treatment focuses on CPR plus identifying and reversing the underlying cause. Epinephrine is the pharmacological agent of choice.

Question 6: Sustained monomorphic ventricular tachycardia with a pulse is initially managed with which approach?

Synchronized cardioversion if unstable, or IV antiarrhythmics (amiodarone or procainamide) if stable (Correct answer)
Immediate unsynchronized defibrillation regardless of hemodynamics
IV adenosine as first-line agent
Observation only

Correct answer: Synchronized cardioversion if unstable, or IV antiarrhythmics (amiodarone or procainamide) if stable

Stable monomorphic VT with a pulse may be treated pharmacologically (amiodarone, procainamide) while unstable VT (hypotension, altered consciousness, chest pain) requires immediate synchronized cardioversion.

The ACLS approach to VT with a pulse depends on hemodynamic stability. Unstable patients (hypotension, syncope, chest pain, pulmonary edema) require synchronized cardioversion immediately (100-200 J biphasic). Stable patients may receive IV amiodarone (150 mg over 10 min) or procainamide. All patients with VT warrant emergent evaluation for underlying ischemia or structural heart disease.

CRAT Life-Threatening Arrhythmias 2

Ventricular fibrillation on an ECG is best described by which appearance?