What is the management algorithm for a 90kg male with ventricular tachycardia (VT), including the starting energy level for electrical cardioversion and post-resuscitation management?

Management Algorithm for Ventricular Tachycardia in a 90kg Male

Immediate Assessment: Determine Hemodynamic Stability

The first and most critical step is to immediately assess hemodynamic stability—look for hypotension, altered mental status, chest pain, signs of shock, or heart failure. 1, 2, 3, 4

• Check blood pressure, mental status, and signs of end-organ hypoperfusion 3, 4
• If the patient shows ANY signs of instability (hypotension, altered consciousness, chest pain, heart failure), proceed directly to electrical cardioversion—do not delay for pharmacologic therapy 1, 2, 4

Treatment Algorithm Based on Stability

For Hemodynamically UNSTABLE VT:

Immediate synchronized cardioversion is the definitive treatment—start with 100 joules for monomorphic VT using a biphasic defibrillator. 1, 2

• Starting energy: 100 J synchronized cardioversion for monomorphic VT 1
• If the patient is conscious but unstable, provide immediate sedation before cardioversion—but do not delay if extremely unstable 1, 2
• If the first shock at 100 J fails, increase the dose in a stepwise fashion 1
• The European Society of Cardiology recommends starting at maximum output, which provides an alternative approach 1
• For polymorphic VT (irregular QRS morphology), use unsynchronized high-energy shocks (defibrillation doses of 200 J) as you would for ventricular fibrillation 1

For Hemodynamically STABLE VT:

Electrical cardioversion remains first-line even for stable patients, but pharmacologic options can be considered. 1, 3

• Obtain a 12-lead ECG to confirm the diagnosis and characterize the VT morphology 1, 3, 4
• Electrical cardioversion with 100 J synchronized is still the preferred approach 1, 3
• If choosing pharmacologic therapy, procainamide is most efficacious (10 mg/kg IV at 50-100 mg/min over 10-20 minutes, monitoring BP and ECG) for patients without severe heart failure or acute MI 1, 5
• Amiodarone (150 mg IV over 10 minutes followed by infusion) is preferred for patients with heart failure or suspected ischemia 1, 3, 4
• Lidocaine is only moderately effective and should be considered only if other options fail or are contraindicated 1, 3

Critical Pitfalls to Avoid

Never use calcium channel blockers (verapamil, diltiazem) for wide-complex tachycardia unless you are absolutely certain it is fascicular VT—they can cause hemodynamic collapse in structural VT. 2, 3, 4

• Do not delay cardioversion in unstable patients while attempting drug therapy 3, 4
• When in doubt about the rhythm diagnosis, treat as VT rather than SVT with aberrancy 2
• Avoid prophylactic antiarrhythmic drugs other than beta-blockers 1, 4

Post-Resuscitation Management

After successful cardioversion, the focus shifts to preventing recurrence and addressing underlying causes.

Immediate Post-Conversion Care:

• Continuous cardiac monitoring for VT recurrence 3, 4
• Obtain 12-lead ECG to assess for ST-segment elevation or ischemic changes 1
• Correct electrolyte imbalances immediately (potassium, magnesium) 1, 4
• Evaluate for acute myocardial ischemia, hypoxia, and acid-base disturbances 4

Pharmacologic Prevention of Recurrence:

• Start IV beta-blockers to prevent recurrent arrhythmias—this is the only prophylactic antiarrhythmic with proven benefit 1
• If VT recurs after cardioversion, administer IV amiodarone (150 mg over 10 minutes, then 1 mg/min for 6 hours, then 0.5 mg/min) to prevent acute reinitiation 1, 2, 4
• Consider lidocaine for recurrent VT not responding to beta-blockers or amiodarone 1

Coronary Evaluation and Revascularization:

• If the patient is comatose post-arrest with STEMI criteria, proceed directly to the catheterization laboratory 1
• For comatose survivors without STEMI, consider ICU stabilization first, then coronary angiography within 2 hours if no obvious non-coronary cause is found 1
• Prompt coronary revascularization is essential for recurrent VT/VF in the setting of acute ischemia 1

Advanced Therapies for Refractory Cases:

• Urgent catheter ablation is indicated for scar-related heart disease with incessant VT or electrical storm despite optimal medical therapy 1, 2
• Consider transvenous overdrive pacing if VT is frequently recurrent and catheter ablation is not immediately available 1
• For hemodynamically unstable patients with refractory VT/VF, consider mechanical circulatory support (LVAD or ECMO) at specialized centers 1

Specific Considerations for Acute MI:

• Most post-MI VT/VF occurs within the first 48 hours 2
• VT occurring beyond 48 hours post-MI warrants careful evaluation including possible electrophysiology study 2
• Oral beta-blockers should be started during hospitalization and continued long-term in all ACS patients without contraindications 1

Energy Dosing Summary for 90kg Patient:

For monomorphic VT with pulse: Start with 100 J synchronized cardioversion (biphasic), escalate stepwise if unsuccessful. 1, 6

• Patient weight does not significantly alter initial energy selection for adults 1
• Monophasic waveforms would require 200 J initially, but biphasic is preferred 1