Background: Nifekalant, a K+ channel blocker available in Japan, is used as often as amiodarone for suppressing electrical storm1 (ES) signs such as ventricular fibrillation and tachycardia (Vf and VT). In our department, nifekalant is a first-choice drug in such situations. It has no inotropic effect and a short half-life. Here, we report a case in which we failed to suppress ES with nifekalant, but succeeded with amiodarone and 16 attempts at electrical cardioversion (EC) after cardiopulmonary bypass (CPB) in cardiac surgery.
Case report: A 65-year-old male, diagnosed with aortic valve stenosis (AS) and angina pectoris, underwent a planned aortic valve replacement (AVR) and cardiac artery bypass. His past history included hypertension and 8 years of dialysis treatment. After starting CPB, cardiac arrest was induced immediately after cardioplegia infusion and maintained with 500 – 700 ml infusion every 30 min. LITA-LAD and SVG-RCA anastomosis, and AVR were performed. When the aorta was unclamped, Vf occurred. Several attempts at EC and four administrations of nifekalant (15 mg) were not effective. Subsequently, we administered three doses of amiodarone (150 mg). This seemed to be effective to stop the ES, which sustained for 80 min. During this period, normothermia was maintained with no electrolyte imbalance, the bypass graft flow was satisfactory, and echocardiography showed only diffuse hypokinesis, which gradually improved toward the weaning of CPB. After ICU admission, no Vf or VT occurred with continuous infusion of amiodarone, and the patient was discharged on the third postoperative day without complication.
Discussion: Nifekalant is an antiarrhythmic agent approved in Japan1. Though some studies show that nifekalant is not at all inferior to amiodarone in managing patients with fatal ventricular arrhythmias2,3, there is no large-scale study comparing the efficacy of the two drugs. We experienced a case in which nifekalant was not effective but amiodarone was. The reason is unknown, but an underlying character of nifekalant, a pure K+ channel blocker, could have been less effective than amiodarone in this case.
References:
1. Guidelines for Drug Treatment of Arrhythmias (JCS 2009)
2. J Anesth 28: 587-592
3. J Cardiovasc Pharmacol 66: 600-609
Learning points:
1. In Japan, nifekalant is used as often as amiodarone in managing patients with fatal ventricular arrhythmias, but there is no comparative study for effectiveness.
2. We experienced a case in which nifekalant was less effective than amiodarone for ES.

A case report of electrical storm during aortic valve replacement and cardiac artery bypass requiring 16 attempts at electrical cardioversion