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Both verapamil and diltiazem are used to control ventricular response during atrial fibrillation (AF). Their effect on the maintenance of AF is not known. The effects of the intravenous and oral administration of verapamil and diltiazem were investigated in 35 patients, 18 with (group I) and 17 without (group II) documented paroxysmal AF. Programmed electrical stimulation, either extra-stimuli or burst atrial pacing, was used to induce AF. In group I, the mean values of the duration of AF before and after the intravenous and oral administration of the calcium antagonists were 31 +/- 12, 112 +/- 49 and 69 +/- 25 minutes, respectively. For group II, the values were 5 +/- 3.4, 39 +/- 13 and 14 +/- 7 minutes, respectively. The differences were statistically highly significant (p less than 0.001), after both oral and intravenous administration compared with the baseline value in both groups. The data suggest that both intravenously and orally administered calcium antagonists enhance sustenance of electrically induced AF, especially in patients with spontaneous arrhythmia. Thus, in patients with paroxysmal AF, verapamil or diltiazem should be administered cautiously, because these drugs may prolong the duration of arrhythmia. Further studies are warranted to investigate the role of calcium antagonists in spontaneously occurring paroxysmal AF.

The use of an antitachycardia pacemaker for the treatment of recurrent, drug resistant nonsyncopal sustained ventricular tachycardia in a 28-year-old patient is described. The report emphasizes the role of electrocardiographic recording during manual activation of the tachycardia response in an outpatient setting. The follow-up covers 12 months with 26 spontaneous tachycardia episodes forcing the patient to go to an emergency room to monitor tachycardia termination. Mean ventricular tachycardia cycle length was 340 +/- 21 ms. Tachycardias were terminated either by the primary or secondary modality without acceleration or degeneration to ventricular fibrillation. Thus, it was possible to assess the efficacy and the safety of the termination programs. Unlike during intensive in-hospital testing, restoration of stable sinus rhythm was complicated by re-emergence of ventricular tachycardia. It is concluded that manual activation with medical supervision provides safe management of selected patients with ventricular tachycardia. However, in-hospital testing overestimated, in this case, the efficacy of tachycardia response modalities to terminate spontaneous tachycardia episodes. The customization of an antitachycardia pacemaker with an automatic implantable cardioverter/defibrillator may increase the quality of life as it would allow switching to automatic pace termination.