Makindo Medical Notes

Related Subjects: |Classical Ventricular Tachycardia |Idiopathic Ventricular Tachycardia |Ventricular Fibrillation |Resuscitation - Adult Tachycardia Algorithm |Resuscitation - Advanced Life Support |Atrial Flutter |Atrial Fibrillation |Wolff-Parkinson White syndrome (WPW) |Supraventricular Tachycardia (SVT)

⚡ Key Rule: Any regular broad complex tachycardia = treat as VT until proven otherwise. >95% of adults with structural heart disease + BCT have VT.

📖 About

• Broad complex QRS: >120 ms (>3 small squares).
• Ventricular Tachycardia (VT): Wide complex tachycardia >120 bpm, usually regular.
• Always treat as potentially peri-arrest.

📊 Classification by Regularity

• Regular BCT:
  • Ventricular Tachycardia (commonest)
  • SVT with aberrant conduction (bundle branch block)
  • Idioventricular rhythm (post-MI, <120 bpm)
  • Atrial flutter with fixed aberrancy
  • SVT/flutter with WPW
• Irregular BCT:
  • Atrial fibrillation with aberrant conduction
  • Pre-excited AF (WPW) – irregular + delta waves
  • Torsades de pointes (polymorphic VT, prolonged QT)

🩺 Clinical Features

• Chest pain, syncope, hypotension, cardiogenic shock → unstable.
• Variable S1 intensity → AV dissociation.
• Past IHD/structural disease strongly favours VT.

🔎 Investigations

• 12-lead ECG if stable.
• Bloods: FBC, U&E, Mg, Troponin.
• Echocardiogram → LV function, structural disease.

📉 ECG Features that Favour VT

• Capture beats – normal narrow complex amid VT.
• Fusion beats – hybrid QRS from atrial + ventricular activation.
• AV dissociation – P waves march through at own rate.
• No RS complexes in chest leads.
• Very broad QRS (>140 ms, esp. with BBB morphology).
• Extreme axis deviation.
• Concordance (all QRS complexes same polarity in V1–V6).
• Deep S in V6, tall monophasic R in V1.
• No response to adenosine (though may unmask flutter).

💡 Mnemonic: “Very Bad A Cardiac Thing” for VT on ECG: Very Broad QRS • Bizarre morphology • AV dissociation • Capture/fusion beats • Torsades clues

⚕️ Management (Resus Council UK)

• Unstable (shock, chest pain, syncope, hypotension, pulmonary oedema): Immediate DC cardioversion (synchronised shock).
• Stable: 12-lead ECG, call cardiology. Antiarrhythmics: IV amiodarone (300 mg over 20–60 min, then infusion). Avoid AV-nodal blockers in WPW.
• Adenosine: May terminate SVT with aberrancy or some idiopathic VTs. ⚠️ Do NOT use in pre-excited AF (can precipitate VF).

🌟 Summary: Regular broad complex tachycardia = VT until proven otherwise. Check for AV dissociation, capture/fusion beats, extreme axis. If unstable → shock. If stable → amiodarone, seek expert help.