Antifibrillatory efficacy of long-term tedisamil administration in a postinfarcted canine model of ischemic ventricular fibrillation.

Abstract

The electrophysiologic and antifibrillatory properties of tedisamil (KC-8857) were studied in vivo in a conscious canine model of sudden cardiac death. Male mongrel dogs were anesthetized, and surgical anterior myocardial infarction was induced by a 2-h occlusion, with reperfusion of the left anterior descending coronary artery. Three to five days after infarction, dogs were subjected to programmed electrical stimulation (PES) to identify those at risk for ischemia-induced ventricular fibrillation. Previous studies documented that dogs with a significant anterior-wall infarction develop ventricular tachycardia in response to PES and are at an increased risk for sudden cardiac death on imposition of a transient ischemic event in a region remote from the infarct-related artery. PES-inducible animals were randomized to either oral placebo or oral tedisamil treatment (3 mg/kg, b.i.d for 4 days, Group 1, n = 8). Control animals received empty gelatin capsules (Group 2, n = 8). The effective refractory period and QTc interval were unchanged after 3 days of oral placebo or tedisamil dosing. Arrhythmic activity after drug administration was not observed in dogs treated with tedisamil. PES induction of ventricular tachycardia was reduced significantly in the tedisamil-treated group (100% inducible before drug vs. 9% inducible after drug; p < 0.05). In the sudden-cardiac-death protocol, tedisamil reduced the incidence of lethal ischemic arrhythmias developing in response to acute posterolateral myocardial ischemia. Tedisamil-treated animals exhibited a 100% compared with a 25% survival rate in the control group (p < 0.05). Anterior-wall infarct size, expressed as a percentage of the left ventricle, did not differ between groups: Group 1 = 20 +/- 1%; Group 2 = 22 +/- 1%. Our findings suggest that tedisamil might be useful in the prevention of malignant ventricular arrhythmias in myocardial ischemic injury.

• Authors: G S Friedrichs, J N Abreu, E M Driscoll Jr, J Borlak, B R Lucchesi
• Journal: Journal of cardiovascular pharmacology (J Cardiovasc Pharmacol) Vol. 31 Issue 1 Pg. 56-66 (Jan 1998) ISSN: 0160-2446 [Print] United States
• PMID: 9456278 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Bridged Bicyclo Compounds, Heterocyclic
• Cardiotonic Agents
• Cyclopropanes
• tedisamil

Topics

• Administration, Oral
• Animals
• Bridged Bicyclo Compounds, Heterocyclic (administration & dosage, adverse effects, blood, pharmacology)
• Cardiotonic Agents (administration & dosage, adverse effects, blood, pharmacology)
• Cyclopropanes (administration & dosage, adverse effects, blood, pharmacology)
• Death, Sudden, Cardiac (etiology)
• Dogs
• Electric Stimulation
• Electrophysiology
• Heart Rate (drug effects)
• Heart Ventricles (drug effects)
• Male
• Myocardial Ischemia (complications, drug therapy)
• Time Factors
• Ventricular Fibrillation (prevention & control)
• Ventricular Function