Internal Diseases and Therapy · MU Sofia

32. Treatment of ventricular arrythmias

Covers the emergency and long-term management of ventricular arrhythmias, starting with cardiac arrest from VF and pulseless VT, including the shock algorithm, shock energy and drug doses in a table. It then goes through sustained monomorphic VT with and without a pulse, polymorphic VT and torsades de pointes, PVCs and non-sustained VT, and prevention of sudden cardiac death with ICD indications, long-term antiarrhythmic drugs, catheter ablation and electrical storm. Tables of shock energies and acute drug doses, an ECG picture of torsades, and an ICD chest X-ray are included.

Inside: 6 sections · 2 labelled pictures · 2 tables · 13 flashcards · 10 min

Topic 32 of 139 in the MU Sofia syllabus for Internal Diseases and Therapy (Medicine, Years 4 and 5). The free AceMed note covers it in 6 sections, about 1,231 words (10 min of reading), with 13 flashcards.

In this note

  1. Reminders and principles
  2. Cardiac arrest: VF and pulseless VT
  3. Sustained monomorphic VT with a pulse
  4. Polymorphic VT and torsades de pointes
  5. Premature ventricular contractions (PVCs) and NSVT
  6. Long-term prevention of sudden cardiac death

Reminders and principles

  • Ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) are cardiac arrest: the two shockable rhythms.
  • Sustained VT lasts > 30 s or needs earlier termination; non-sustained VT (NSVT) is ≥ 3 beats at > 100 beats per minute ending within 30 s.
  • The first question is always pulse and haemodynamic stability; the second, the underlying heart (European Society of Cardiology, ESC 2022 guideline on ventricular arrhythmias and sudden cardiac death, SCD).
  • Correct the triggers in every patient: myocardial ischaemia (urgent coronary angiography), potassium (keep ≥ 4.0 mmol/L) and magnesium, hypoxia, acidosis, proarrhythmic drugs (QT-prolonging drugs, digoxin), thyrotoxicosis, decompensated heart failure.
  • Draw blood for electrolytes (K, Mg, Ca), urea and creatinine, troponin and blood gases; record a 12-lead electrocardiogram (ECG) of any tachycardia when the patient is stable.

Cardiac arrest: VF and pulseless VT

Advanced life support algorithm of the European Resuscitation Council (the American Heart Association version is very similar):

  1. Confirm arrest (unresponsive, not breathing normally), call the resuscitation team, start cardiopulmonary resuscitation (CPR) 30:2: compressions 100–120/min, 5–6 cm deep, minimal pauses.
  2. Attach the defibrillator, check the rhythm. VF/pulseless VT → one unsynchronised shock as soon as possible, then immediately resume CPR for 2 minutes without checking the pulse.
  3. Check the rhythm every 2 minutes; shock again while it stays shockable.
  4. After the 3rd shock: adrenaline (epinephrine) 1 mg and amiodarone 300 mg intravenously or intraosseously (IV/IO); then adrenaline 1 mg every 3–5 minutes (every other cycle) and amiodarone 150 mg after the 5th shock. Lidocaine 1 mg/kg (about 100 mg, then 50 mg) if amiodarone is unavailable.
  5. Meanwhile: airway (supraglottic device or intubation), IV or IO access, waveform capnography, and the reversible causes — 4 Hs (hypoxia, hypovolaemia, hypo-/hyperkalaemia and other metabolic causes, hypothermia) and 4 Ts (thrombosis — coronary or pulmonary, tension pneumothorax, tamponade, toxins).
  • Witnessed, monitored VF (coronary care unit, catheter laboratory): up to three quick successive shocks before starting compressions.
  • Refractory VF: change pad position (anterior–posterior), mechanical CPR and urgent coronary angiography, extracorporeal CPR in selected centres.
  • After return of spontaneous circulation: 12-lead ECG, emergency angiography if ST elevation, oxygen saturation 94–98%, mean arterial pressure ≥ 65 mmHg, prevent fever, look for the cause.

Never delay the shock for drugs or airway: survival falls by about 10% for every minute of VF without defibrillation.

Shock energies

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