Clinical Suppression of Refractory Ventricular Tachycardia with Oral Bretylium Not Predicted by Electrophysiologic Drug Testing: Case Report

8 Feb
2015

Cardiac catheterization revealed a totally occluded left anterior descending coronary artery and severely depressed systolic function, with an ejection fraction of 0.25 percent. A large anteroapical aneurysm was present. Due to the extensive size of the aneurysm and his poor left ventricular function,the patient was believed not to be a surgical candidate. High-dose therapy with lidocaine (6 mg/min, and serum levels of 16|mg/ml) may have decreased the episodes of VT, but caused seizures. Lidocaine was discontinued, and intravenous bretylium was reinstituted with a 10-mg/kg bolus and a 3-mg/min infusion. Sustained VT was suppressed, but episodes of nonsustained VT continued. Amiodarone (1,800 mg daily) was started in combination with intravenous bretylium. lumigan eye drops

After eight days, bretylium was discontinued, but sustained VT again returned; however, the VT was now polymorphic and quite rapid, with a cycle length of 210 ms (rate, 291 beats per minute). Multiple DC cardioversions were required for termination. Bretylium was restarted, and VT was suppressed. Amiodarone dosage was reduced to 800 mg/day. On the 18th day of this combination, polymorphic sustained VT and VF developed. Defibrillation was required. Amiodarone was discontinued. Bretylium alone was continued, and all VT was abated within 48 hours. Amiodarone (600 mg) was restarted but promptly caused recurrence of VT within 24 hours and was considered proarrhythmic. The patient was maintained on intravenous bretylium alone (3 mg/min).
Bethanidine, an oral congener of bretylium, was obtained from Marvin Bacaner, M.D., and the A. H. Robbins Co. The investigational protocol required electrophysiologic testing after a single loading dose. The infusion of bretylium was discontinued, and oral bethanidine (1,500 mg) was started three hours later. Sustained VT was induced from the right ventricular outflow tract using triple ventricular extrastimuli during ventricular drive at a 500-ms cycle length (Fig 1A). Induced VT had a cycle length of 280 ms and had a left bundle-branch morphology with right axis deviation.

Figure 1 A (top). Sustained VT was induced with triple ventricular extrastimuli (S2, S3, and S4) during ventricular drive at right ventricular basal septum (RVS). patient had received oral bethanidine; VT had morphology of left bundle-branch block and right axis deviation at cycle length of 280 msec. B (bottom). Sustained VT was induced from RVS with triple extrastimuli (S2, S3, and S4) during ventricular drive on oral bretylium. Morphology was left bundle-branch block and left axis at cycle length of 260 msec. Although morphologies are different, VT cycle lengths are similar. R\A, Right ventricular apex.

Figure 1 A (top). Sustained VT was induced with triple ventricular extrastimuli (S2, S3, and S4) during ventricular drive at right ventricular basal septum (RVS). patient had received oral bethanidine; VT had morphology of left bundle-branch block and right axis deviation at cycle length of 280 msec. B (bottom). Sustained VT was induced from RVS with triple extrastimuli (S2, S3, and S4) during ventricular drive on oral bretylium. Morphology was left bundle-branch block and left axis at cycle length of 260 msec. Although morphologies are different, VT cycle lengths are similar. R\A, Right ventricular apex.

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