Effects of verapamil and procainamide on acute atrial electrical remodeling induced by short-term rapid atrial pacing in humans.
Atrial electrical remodeling (ER) after spontaneous or pacing-induced atrial fibrillation has been previously described in humans. We investigated atrial ER induced by a 5-minute period of rapid atrial pacing and the pharmacologic effects of verapamil and procainamide on this atrial ER phenomenon. The atrial effective refractory periods (ERPs) at drive cycle lengths of 400 (ERP 400 ) and 600 (ERP 600 ) ms, at five representative atrial sites (high right atrium [HRA]; proximal, middle and distal coronary sinus; interatrial septum), were determined in 20 patients at baseline and immediately after cessation of a 5-minute period of rapid pacing from the HRA at a rate of 150 bpm. The degrees of atrial ERP 400 and ERP 600 shortening after pacing were calculated as acute atrial ER. The same protocol was repeated in another 15 patients after intravenous administration of verapamil (0.15 mg/kg) and in another 15 patients after intravenous administration of procainamide (15 mg/kg). The results demonstrated that, in the control state acute atrial ER can be significantly demonstrated at each atrial representative site ( p < 0.001). The mean ERP 400 and ERP 600 shortenings were 9 +/- 4% and 8 +/- 4%, respectively. After procainamide infusion, but not after verapamil, baseline ERP 400 and ERP 600 values were significantly prolonged at the five representative atrial sites ( p < 0.01). Acute atrial ER could still be demonstrated at each atrial site after procainamide or verapamil infusion ( p < 0.001). In conclusion, acute atrial ER can be demonstrated after only a 5-minute period of rapid atrial pacing in humans. Intravenous verapamil or procainamide does not abolish this ER process.
Chu
Chih-Sheng
CS
Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital and Department of Cardiology, Faculty of Internal Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Lee
Kun-Tai
KT
Cheng
Kai-Hong
KH
Lin
Tsung-Hsien
TH
Lee
Min-Yi
MY
Voon
Wen-Chol
WC
Lai
Wen-Ter
WT
Chu
Chih-Sheng
CS
Lee
Kun-Tai
KT
Cheng
Kai-Hong
KH
Lin
Tsung-Hsien
TH
Lee
Min-Yi
MY
Voon
Wen-Chol
WC
Sheu
Sheng-Hsiung
SH
Lai
Wen-Ter
WT
D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D002304:Cardiac Pacing, Artificial; D005260:Female; D006325:Heart Atria / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011342:Procainamide / Q000494:pharmacology*; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D014700:Verapamil / Q000494:pharmacology*
D000889:Anti-Arrhythmia Agents; D014700:Verapamil; D011342:Procainamide