Intravenous dantrolene does not exhibit calcium channel blocking effects on the cardiac conduction system in humans.
In malignant hyperthermia, dantrolene, a drug assumed to possess calcium channel blocking properties, effectively suppresses supraventricular and ventricular arrhythmias. To investigate antiarrhythmic properties of dantrolene, six patients (three women and three men, age 42 +/- 18 yr) with symptomatic atrioventricular (AV)-nodal reentry tachycardia were studied. Electrocardiographic measurements included sinus cycle length, PQ-interval, width of the QRS-complex, and QT- and rate-corrected QT-interval. During the electrophysiologic study, effective refractory periods of the right atrium, AV node, right ventricle, and AV-nodal conduction intervals were determined, and AV-nodal reentry tachycardia was induced in all patients. Dantrolene was administered intravenously over a period of 15 min at doses of 1.0, 1.5, or 3.0 mg/kg in two patients each. The dosage was not further increased because of side effects at the dose of 3.0 mg/kg. After the infusion of dantrolene, the electrocardiographic measurements and electrophysiologic study were repeated. The plasma concentrations of dantrolene ranged from 1.69 to 6.61 micrograms/ml at the time of the electrophysiologic study. After dantrolene administration, the sinus cycle length shortened from 686 +/- 80 to 622 +/- 55 ms (P less than 0.05). No significant changes of any other parameter could be demonstrated after intravenous dantrolene. AV-nodal reentry tachycardia remained inducible in all patients without change of the tachycardia cycle length and without change in coupling intervals of tachycardia-inducing extrastimuli. Antiarrhythmic properties of dantrolene could not be demonstrated in patients with AV-nodal reentry tachycardia at therapeutic doses.(ABSTRACT TRUNCATED AT 250 WORDS)
Kentsch
M
M
Department of Anesthesiology, University Hospital, Eppendorf, Hamburg, Federal Republic of Germany.
Roewer
N
N
Kunze
K P
KP
Kuck
K H
KH
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D003620:Dantrolene / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008305:Malignant Hyperthermia / Q000188:drug therapy; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000188:drug therapy
D000889:Anti-Arrhythmia Agents; D002121:Calcium Channel Blockers; D003620:Dantrolene