What else can be done for a post-operative Coronary Artery Bypass Graft (CABG) patient experiencing frequent long runs of Ventricular Tachycardia (VTach) with hypotension?

Management of Ventricular Tachycardia with Hypotension in Post-CABG Patients

For a post-operative CABG patient experiencing frequent long runs of ventricular tachycardia with hypotension, immediate treatment with intravenous amiodarone is recommended as the most effective intervention. 1

Immediate Management

First-Line Treatment

• IV Amiodarone administration:
  • Initial loading dose: 150 mg IV over 10 minutes 1
  • Follow with infusion of 1 mg/min for 6 hours (360 mg) 1
  • Then maintenance infusion of 0.5 mg/min (720 mg over 24 hours) 1
  • Use central venous catheter for concentrations >2 mg/mL to avoid phlebitis 1

Hemodynamic Support

• Maintain mean arterial pressure >60 mmHg 2
• Consider vasopressors if hypotension persists despite adequate fluid resuscitation
• Monitor urine output (target >0.5 mL/kg/hr) 2
• Consider inotropic support with dobutamine or milrinone if evidence of low cardiac output syndrome 2

Secondary Interventions

Electrolyte Management

• Aggressively correct electrolyte abnormalities:
  • Maintain potassium >4.5 mEq/L
  • Maintain magnesium >2.0 mg/dL
  • Check and correct calcium levels

Pacing Options

• Consider temporary ventricular pacing if not already in place 3
• Overdrive pacing can be effective for terminating recurrent VT
• Consider atrial pacing if AV synchrony would improve hemodynamics

Additional Pharmacologic Options

• If amiodarone is ineffective or contraindicated:
  • Lidocaine: 1-1.5 mg/kg IV bolus, followed by infusion of 1-4 mg/min 4
  • Procainamide: 20-50 mg/min IV until arrhythmia suppressed, hypotension occurs, QRS widens by >50%, or maximum dose of 17 mg/kg reached 4
  • Beta-blockers (if hemodynamics permit): Consider metoprolol 5 mg IV slowly, may repeat up to 3 doses 2

Diagnostic Workup

• Obtain 12-lead ECG during and after VT episodes
• Check cardiac enzymes to rule out ongoing ischemia
• Echocardiography to assess:
  • Ventricular function
  • Regional wall motion abnormalities
  • Valvular function
  • Presence of pericardial effusion

Special Considerations

Potential Causes to Address

• Myocardial ischemia: Most common cause of post-CABG VT 4
  • Consider urgent coronary angiography if suspected graft failure
• Electrolyte abnormalities: Correct aggressively
• Medication effects: Review all medications for QT-prolonging agents
• Mechanical irritation: Check position of temporary pacing wires or central lines

Cautions with Amiodarone

• Monitor for hypotension during loading dose 1
• Be aware of potential for acute pulmonary toxicity, even with short-term use 5, 6
• Watch for QT prolongation and torsades de pointes 7
• Use with caution in patients with severe hepatic disease

Long-term Management

• If VT is controlled:

  • Continue oral amiodarone (200-400 mg daily) after IV loading 4
  • Consider ICD implantation before discharge if VT is due to structural heart disease 4
  • Optimize beta-blocker therapy 2
  • Ensure ACE inhibitors or ARBs are initiated for patients with reduced LVEF 4

• If VT persists despite medical therapy:

  • Consider urgent electrophysiology consultation
  • Evaluate for catheter ablation of VT
  • Consider mechanical circulatory support if refractory VT with cardiogenic shock

Pitfalls and Caveats

• Do not delay electrical cardioversion in hemodynamically unstable patients
• Avoid class IC antiarrhythmics (flecainide, propafenone) in post-CABG patients with coronary artery disease 4
• Be cautious with amiodarone in patients with pulmonary disease or recent lung injury 5, 6
• Monitor for drug interactions, particularly with warfarin and digoxin
• Do not rely solely on rate control strategies for ventricular tachycardia

Ventricular tachycardia with hypotension in the post-CABG setting represents a medical emergency requiring prompt intervention. Amiodarone has demonstrated efficacy in this setting, with studies showing rapid onset of antiarrhythmic activity and reduction of VT episodes by up to 85% compared to baseline 1.