Evaluation of Electrophysiological PropertiesTo achieve a stable condition, each dog was allowed to recover for 7 days after the initial surgical procedure without any pacing. Then, rapid atrial pacing (400 beats/min) was initiated and continued for 2 weeks (rapid pacing phase). This pacing was performed at an output of 4-fold the diastolic threshold and a pulse width of 2 ms. After this continuous rapid pacing, the pacing was ceased, and each dog was allowed to recover for 1 week (recovery phase). On days 0, 3, 7, 10 and 14 during the rapid pacing phase, the rapid pacing was stopped temporarily to evaluate the atrial Background The effect of bepridil, a multichannel blocker, on atrial electrical remodeling was evaluated in a canine rapid atrial stimulation model.
Methods and ResultsIn 10 beagle dogs, the right atrial appendage (RAA) was paced at 400 beats/min for 2 weeks. The atrial electrophysiological parameters, including effective refractory period (AERP), were evaluated at three atrial sites: RAA, the right atrium close to the inferior vena cava (IVC) and the left atrium (LA), during the time course of rapid pacing. Five of the dogs were given bepridil (10 mg·kg -1 ·day -1 po). In the control group, AERP was significantly shortened at all atrial sites and the AERP shortening (∆AERP) was larger for the RAA and LA than at the IVC site (p<0.05). In the bepridil group, ∆AERP was smaller than that of the controls at all atrial sites, and the AERP started to return slowly to the pre-pacing level in the second week, regardless of the continuation of rapid pacing. Conclusions In a canine rapid atrial stimulation model, bepridil suppressed AERP shortening. Bepridil might have a reverse electrical remodeling effect, at least for AERP shortening, because it showed slow recovery of AERP in the subacute phase of rapid atrial pacing. (Circ J 2006; 70: 206 -213)
Background Ventricular tachyarrhythmias (VT/VF) are 1 of the most important factors determining the prognosis of patients with heart failure (HF). Although priority is given to implantable cardioverter defibrillator (ICD) therapy for the prevention of sudden cardiac death, electrophysiologic-study (EPS)-guided preventive therapy could be important for reducing the number of cardiac events.
Methods and ResultsOf 864 patients with a history of HF, an EPS was performed in 168 and 121 had inducible VT/VF. Under the basic therapy of an ICD, additional catheter ablation was attempted for 95 of 124 monomorphic VT foci in 74 patients, and 78 of the VT were successfully ablated. The prognoses were compared among 5 patient groups with different results for the EPS and catheter ablation: (1) success group (n=43), (2) failure group (n=15), (3) not attempted group (n=16), (4) VF group (n=47), and (5) no inducible VT/VF group. During a follow-up period of 31±22 months, the incidence of VT/VF was lower in the success and no inducible VT/VF groups than in the other groups (p=0.0018), although a significant difference was not observed for the total deaths. Conclusion EPS-guided preventive therapy using an ICD and catheter ablation can be useful, at least for the reduction of arrhythmic events in patients with HF. (Circ J 2008; 72: 268 -273)
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