What is the recommended energy in joules to synchronize cardiovert sustained ventricular tachycardia (V-tach)?

From the Guidelines

For synchronized cardioversion of sustained ventricular tachycardia, the recommended initial energy dose is 100 J. This is based on the guidelines from the American College of Cardiology/American Heart Association task force on practice guidelines, as stated in the 2004 Circulation journal article 1. The guidelines specify that episodes of sustained monomorphic VT associated with angina, pulmonary edema, or hypotension should be treated with a synchronized electric shock of 100 J initial monophasic shock energy.

Key Considerations

• Increasing energies may be used if the initial shock is not successful, as indicated by the guidelines 1.
• Brief anesthesia is desirable if hemodynamically tolerable, to minimize patient discomfort during the procedure.
• It is essential to ensure proper electrode placement and good skin contact to maximize the effectiveness of the cardioversion.
• The patient should be adequately sedated, and oxygen should be administered, with resuscitation equipment immediately available.
• Synchronized cardioversion is preferred for ventricular tachycardia with a pulse, as it reduces the risk of inducing ventricular fibrillation by timing the shock to avoid the vulnerable period of the cardiac cycle. However, if the patient is hemodynamically unstable or pulseless, immediate unsynchronized defibrillation should be performed instead.

From the Research

Synchronized Cardioversion for Ventricular Tachycardia

• The energy required for synchronized cardioversion of sustained ventricular tachycardia can vary, with studies suggesting a range of energies may be effective 2.
• One study found that truncated exponential shocks of 0.025 to 2.0 joules synchronized to the QRS complex terminated episodes of recurrent sustained ventricular tachycardia, with a cardioversion threshold of less than or equal to 0.25 joule in some patients and 0.75 to 2.0 joules in others 2.
• Specifically, the study reported that shocks of 0.75 joule and 2.0 joule failed to terminate VT in one patient each, while higher energies were not tried due to hemodynamic decompensation 2.
• The same study noted that shocks less than or equal to 0.5 joule were well tolerated by awake, unsedated patients, with no repetitive ventricular activity observed in 140 out of 141 synchronized shocks 2.

Comparison of Energy Levels

• The exact energy level required for synchronized cardioversion may depend on individual patient factors, such as the presence of hemodynamic instability or the use of antiarrhythmic medications 3, 2.
• While some studies suggest that lower energy levels (e.g., 0.025 to 2.0 joules) may be effective for cardioversion, others have used higher energy levels (e.g., 25 joules) to terminate ventricular fibrillation 2.
• It is essential to consider the specific clinical context and patient characteristics when determining the appropriate energy level for synchronized cardioversion 3, 2, 4, 5, 6.