[Electrophysiological mechanism of combination therapy with disopyramide and propranolol for paroxysmal atrial fibrillation].
OBJECTIVE
Combined administration of propranolol and disopyramide treatment often leads to better results in patients with atrial fibrillation refractory to only disopyramide administration. The electrophysiological mechanism of this combination therapy was investigated.


METHODS
Nineteen patients with paroxysmal atrial fibrillation without organic heart disease were studied. The indices for atrial vulnerability were compared in the control state, 10 min after injection of disopyramide (2 mg/kg) and 10 min after additional administration of propranolol (0.2 mg/kg).


RESULTS
Administration of both drugs did not significantly change the percentage fragmented atrial activity and the interatrial conduction delay. Disopyramide increased the atrial effective refractory period and the wavelength index, defined as the ratio of the atrial effective refractory period to the interatrial conduction delay and represented the length of the reentry circuit. Additional injection of propranolol caused further increases in both values.


CONCLUSIONS
Combination therapy with disopyramide and propranolol improves atrial vulnerability by increasing the wavelength.
Gondo
N
N
Second Department of Internal Medicine, School of Medicine, Fukuoka University, Nanakuma 7-45-1, Jonan-ku, Fukuoka 814-0180.
Kumagai
K
K
Yamanouchi
Y
Y
Annoura
M
M
Saku
K
K
D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D004206:Disopyramide / Q000008:administration & dosage*; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011433:Propranolol / Q000008:administration & dosage*
D000889:Anti-Arrhythmia Agents; D011433:Propranolol; D004206:Disopyramide