## Clinical Scenario Analysis This patient has **haemodynamically unstable ventricular tachycardia (VT)** with: - Hypotension (88/56 mmHg) - Altered consciousness (drowsy) - Wide complex tachycardia with AV dissociation (pathognomonic for VT) - History of MI (scar substrate for re-entry) ## Management Algorithm for Unstable VT ```mermaid flowchart TD A[Wide Complex Tachycardia]:::outcome --> B{Haemodynamically Stable?}:::decision B -->|No: Hypotension, LOC, Shock| C[Synchronized DC Cardioversion]:::action B -->|Yes: Normal BP, Alert| D[Drug Therapy]:::action C --> E[100 J initial, escalate if needed]:::action D --> F[IV Amiodarone or Procainamide]:::action E --> G[Reassess rhythm]:::outcome F --> G ``` ## Key Point: **Haemodynamic instability is the PRIMARY indication for immediate cardioversion, regardless of drug availability.** Drugs delay definitive therapy in unstable patients. ## High-Yield Facts: - **Synchronized DC cardioversion** is the gold standard for haemodynamically unstable VT - Starting energy: **100 J** (biphasic defibrillator); escalate to 200 J, 300 J, 360 J if needed - Patient is conscious but drowsy → brief sedation (etomidate 0.2 mg/kg IV) if time permits, but do NOT delay cardioversion - AV dissociation confirms VT diagnosis (adenosine would be ineffective and dangerous) ## Clinical Pearl: **"Haemodynamic instability trumps all other considerations."** Even if the patient were conscious and alert, hypotension + syncope + VT = immediate cardioversion. ## Why Drugs Are Wrong Here: - Amiodarone and procainamide take 10–30 minutes to work - Patient is hypotensive and at risk of cardiogenic shock - Adenosine is contraindicated in VT (only works for SVT) [cite:Harrison 21e Ch 297]
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