From the Guidelines
Management of unstable polymorphic ventricular tachycardia requires immediate defibrillation with an unsynchronized electric shock, as recommended by the most recent guidelines 1. The initial shock energy should be 200 J, and if unsuccessful, a second shock of 200 to 300 J should be given, and, if necessary, a third shock of 360 J, as suggested by the ACC/AHA guidelines 1. If the patient is pulseless, initiate CPR and follow ACLS protocols for cardiac arrest. After cardioversion, identify and treat the underlying cause, which commonly includes acute myocardial ischemia, electrolyte abnormalities (particularly hypokalemia and hypomagnesemia), or medication toxicity. Key interventions include:
- Administering IV magnesium sulfate 2g over 15 minutes regardless of serum magnesium levels, as supported by observational studies 1
- Correcting electrolyte abnormalities by administering potassium to maintain levels >4.0 mEq/L and magnesium >2.0 mg/dL
- Using beta-blockers if ischemia is the underlying cause, as recommended by the ACC/AHA/ESC guidelines 1
- Considering amiodarone 150 mg IV over 10 minutes followed by infusion at 1 mg/min for 6 hours, then 0.5 mg/min for recurrent episodes, as suggested by the ACC/AHA/ESC guidelines 1 It is essential to avoid class I antiarrhythmics and QT-prolonging medications, as they can exacerbate the condition. The management strategy should be guided by the underlying cause of the polymorphic VT, with a focus on addressing the physiological triggers that promote reentry circuits and abnormal automaticity in the ventricles, as emphasized by the European Heart Journal guidelines 1.
From the FDA Drug Label
Amiodarone hydrochloride injection is indicated for initiation of treatment and prophylaxis of frequently recurring ventricular fibrillation (VF) and hemodynamically unstable ventricular tachycardia (VT) in patients refractory to other therapy. In the event of breakthrough episodes of VF or hemodynamically unstable VT, use 150 mg supplemental infusions of amiodarone (mixed in 100 mL of D5W and infused over 10 minutes to minimize the potential for hypotension)
The management of unstable polymorphic ventricular tachycardia (VT) involves the use of amiodarone. Key points include:
- Initial treatment: Amiodarone can be used for initiation of treatment and prophylaxis of frequently recurring VT.
- Breakthrough episodes: In the event of breakthrough episodes of VT, supplemental infusions of 150 mg amiodarone can be used. 2 2
From the Research
Management of Unstable Polymorphic Ventricular Tachycardia (VT)
The management of unstable polymorphic VT is crucial due to its potentially life-threatening nature.
- The symptom most suggestive of unstable ventricular tachycardia is a change in mental status or loss of consciousness 3.
- Unstable ventricular tachycardia requires immediate cardioversion 3.
- After converting ventricular tachycardia to a sinus rhythm, administer an antiarrhythmic infusion 3.
- Polymorphic ventricular tachycardia comprises a variety of different subforms, each requiring a different therapeutic approach 4, 5.
- Medications considered the treatment of choice for one form of polymorphic ventricular tachycardia are contraindicated for the other 5.
- For catecholaminergic polymorphic ventricular tachycardia (CPVT), beta blockers (BB) are the cornerstone pharmacological therapy for the prevention of cardiac event 6.
- The dose of BB should be highly tolerable, preferably nadolol, and efficiency of BB is undeniable but uncompleted 6.
- On top of BB, one can propose the use of Calcium channel blockers or Class 1c antiarrythmic drugs, such as Flecainide, to reduce exercise-induced premature ventricular contraction and ventricular arrhythmia 6.