Ventricular Rhythms
Wide QRS (≥0.12 s): the impulse starts in the ventricles
Premature ventricular contractions (PVCs)
An early, wide, bizarre beatLook for: an early beat with a wide, bizarre QRS and no P wave before it; the T wave points the opposite way to the QRS; usually followed by a full compensatory pause.
Patterns: bigeminy (every 2nd beat), trigeminy (every 3rd), couplet (2 in a row), 3 or more in a row = VT.
Causes: hypokalemia, hypomagnesemia, hypoxia, MI/ischemia, HF, caffeine, nicotine, alcohol, stimulants, digoxin toxicity.
Patterns: bigeminy (every 2nd beat), trigeminy (every 3rd), couplet (2 in a row), 3 or more in a row = VT.
Causes: hypokalemia, hypomagnesemia, hypoxia, MI/ischemia, HF, caffeine, nicotine, alcohol, stimulants, digoxin toxicity.
Nursing:
- Assess the patient and pulse (a PVC may not produce a pulse: pulse deficit).
- Check K⁺ and Mg²⁺, oxygenation, and meds; treat the cause.
- Report: increasing frequency, couplets, runs, multifocal PVCs, or R-on-T (PVC landing on the T wave can trigger VT/VF).
- Occasional PVCs in a healthy person are often benign.
Ventricular tachycardia (VT)
Check for a pulse: it decides the treatmentRate100–250 (usually >150)
RhythmRegular (monomorphic)
P waveNot seen
PRNone
QRSWide (≥0.12 s), bizarre
| Patient status | Treatment |
|---|---|
| Pulseless | Treat as VF: CPR + defibrillation, epinephrine, amiodarone or lidocaine. |
| Pulse, unstable | Synchronized cardioversion (sedate if possible). |
| Pulse, stable | 12-lead EKG, expert consult; antiarrhythmic such as amiodarone 150 mg IV over 10 min (or procainamide); correct K⁺/Mg²⁺. |
Causes: MI/ischemia, cardiomyopathy, HF, low K⁺ or Mg²⁺, hypoxia, acidosis, drug toxicity (digoxin, QT-prolonging drugs).
Torsades de pointes
Polymorphic VT + long QTQRS "twists" around the baseline, getting taller then shorter.
Causes: QT-prolonging drugs (haloperidol, ondansetron, methadone, macrolides, fluoroquinolones, citalopram, amiodarone, sotalol), low Mg²⁺, low K⁺, low Ca²⁺.
Treatment: magnesium sulfate 1–2 g IV; stop QT-prolonging drugs; correct K⁺. Pulseless or unstable → defibrillate (unsynchronized: polymorphic rhythms can't be synced).
Updated: what changed
Vasopressin is no longer in the adult cardiac arrest algorithm (removed 2015). Epinephrine is the vasopressor used.
Lidocaine is an accepted alternative to amiodarone for shock-refractory VF/pulseless VT.
Older guides that list "vasopressin 40 units" for VT/VF are out of date.
Lidocaine is an accepted alternative to amiodarone for shock-refractory VF/pulseless VT.
Older guides that list "vasopressin 40 units" for VT/VF are out of date.