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Terminating SVT-mediated recurrent ventricular fibrillation with verapamil
1Emergency Medical Services, Magen David Adom and Emergency Department, Shaare Zedek Medical Center, Jerusalem, Israel.
Insights
Verapamil can terminate life-threatening ventricular fibrillation caused by supraventricular tachycardia when other drugs fail. This finding offers a new treatment option for this critical cardiac condition.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Verapamil is a first-line treatment for supraventricular dysrhythmias, ischemic heart disease, and hypertension.
- Its efficacy in treating ventricular dysrhythmias is not well-established.
Observation:
- Five cases of recurrent ventricular fibrillation, secondary to supraventricular tachycardia, were refractory to conventional antidysrhythmics (lidocaine, procainamide, bretylium).
- Verapamil successfully terminated these episodes of ventricular fibrillation.
Findings:
- Verapamil demonstrated efficacy in terminating drug-refractory ventricular fibrillation mediated by supraventricular tachycardia.
- Proposed mechanisms include reduced myocardial oxygen demand, direct anti-ischemic effects, and direct antidysrhythmic actions.
Implications:
- Verapamil should be considered for patients with supraventricular tachycardia-mediated recurrent ventricular fibrillation unresponsive to standard treatments.
- This expands the therapeutic role of verapamil in managing complex cardiac arrhythmias.
Abstract:
Verapamil has been established as the drug of choice in the treatment of supraventricular dysrhythmias and is recognized as useful in the treatment of ischemic heart disease and hypertension. However, verapamil has not generally been considered helpful in the treatment of ventricular dysrhythmias. Five cases are reported in which verapamil was used to terminate a cycle of supraventricular tachycardia-mediated recurrent ventricular fibrillation that could not be suppressed by conventional antidysrhythmics such as lidocaine, procainamide, and bretylium, Proposed mechanisms of verapamil's beneficial effect in this usually fatal situation include (1) a reduction in oxygen consumption related to the reduction in heart rate, thereby raising the ventricular fibrillation threshold; (2) direct anti-ischemic effect; and (3) a direct antidysrhythmic effect. These proposed mechanisms are substantiated by clinical studies. On the basis of this observation, it is recommended that in a situation of supraventricular tachycardia-mediated recurrent ventricular fibrillation that cannot be terminated by conventional antidysrhythmics, the administration of verapamil should be considered.