論文

We investigated the recovery of electrophysiological parameters from electrical remodeling after conversion of chronic lone atrial fibrillation in humans. Clinical studies have shown that the longer atrial fibrillation lasts, the more difficult it becomes to maintain the sinus rhythm after cardioversion. To explore the effects of the duration of atrial fibrillation on changes of electrophysiological parameters after conversion, we determined the atrial effective refractory period and P wave duration during right atrial pacing at 1 and 24 h after electrical cardioversion in 15 patients with chronic lone atrial fibrillation (median duration, 6 months). By 24 h after cardioversion, the effective refractory period at a pacing cycle length of 600 ms increased from 225±19 to 254±27 ms. However, the P wave duration did not decrease significantly 24 h after conversion. As the duration of atrial fibrillation became longer, the prolongation of effective refractory period was more delayed (P<0. 001, r=0.82), and the shortening of P wave duration was significantly smaller within 24 h after cardioversion (P<0. 001, r=0.67). After cardioversion of chronic lone atrial fibrillation, the recovery of shortened atrial refractoriness and prolonged intraatrial conduction time is dependent on the duration of preexisting atrial fibrillation. © 2001 Elsevier Science Ireland Ltd. All rights reserved.

We describe 2 cases of congestive heart failure due to atrial tachyarrhythmias, which were successfully treated by a new Ikr blocker, nifekalant. Case 1 was 59-year old male with congestive heart failure caused by atrial fibrillation with rapid ventricular response due to manifest WPW syndrome. Intravenous administration of nifekalant (0.3mg/kg) successfully slowed ventricular response with reducing the frequency of the pre-excitation. Case 2 was 73-year old male having a history of hypertention, also exhibited heart failure caused by atrial flutter with 2 to 1 or 3 to 1 atrioventricular conduction. The atrial flutter was successfully converted to sinus rhythm with the same dose of intravenous nifekalant. In both cases, the heart failure did not aggravated by the use of nifekalant but recovered soon by treating atrial tachyarrhythmias. Intravenous nifekalant may be a useful option in the management of atrial tachyarrhythmia with heart failure.

A 62 year old man was admitted for evaluation of recurrent episodes of syncope. A surface ECG showed frequent repetitive premature ventricular complexes of right ventricular outflow tract origin. Ventricular fibrillation was inducible by programmed electrical stimulation but otherwise cardiac evaluation was unremarkable. A diagnosis of idiopathic ventricular fibrillation was made and an implantable cardioverter-defibrillator (ICD) was installed. However, spontaneous ventricular fibrillation recurred, requiring repeated ICD discharges. The ventricular fibrillation was reproducibly triggered by a single premature ventricular complex with a specific QRS morphology. Radiofrequency catheter ablation was carried out to eradicate this complex. No ventricular fibrillation has developed after this procedure, and the patient does not require drug treatment.

We report a case of Wolff-Parkinson-White syndrome coexistent with atresia of the coronary sinus (CS) ostium and persistence of the left superior vena cava. The accessory pathway was located at the blind end of the CS, which was bumped with mechanical loss of preexcitation during mapping by a catheter from within the CS. The accessory pathway was successfully ablated with radiofrequency energy applied to this site from the right atrium. This unique combination of anatomically matched anomalies may be important in suggesting a potential embryologic link between the accessory pathway and the coronary vein.