title: Bradycardia-mediated tachyarrhythmias in congenital heart disease and responses to chronic pacing at physiologic rates.
abstract: The coexistence of bradycardia and a tachyarrhythmia may preclude effective pharmacologic treatment of 1 arrhythmia without paradoxic aggravation of the other. This study evaluated the potential relation between the 2 types of arrhythmias and the effect of conventional modes and rates of pacing for bradycardia on the frequency of the associated tachyarrhythmias. Twenty-one young patients, aged 2 to 19 (mean 11) years with congenital heart disease and a tachyarrhythmia occurring in the setting of chronic bradycardia were studied. The effects of pacing were evaluated by comparison of the number of episodes of clinical tachycardia during the 12-month intervals before and after pacemaker implantation. During these intervals, antiarrhythmic drug therapy was not altered. Patients were analyzed as independent groups, based on the type of tachyarrhythmia: supraventricular (n = 5), atrial flutter (n = 9) and ventricular (n = 7). The modes of chronic pacing were AAI (n = 4), DDD (n = 6) and VVI (n = 11). The prevention of bradycardia by pacing was associated with a significant decrease in the frequency of supraventricular (p = 0.008) and ventricular (p = 0.02) tachyarrhythmias. However, the frequency of atrial flutter was not altered. Prevention of tachycardia was more frequently associated with the AAI and DDD modes of pacing compared to VVI (p = 0.08). Pacing represents an effective therapy for certain tachyarrhythmias associated with chronic bradycardia, although critical modes may be required.
authors.affiliation: Department of Pediatrics, Oregon Health Sciences University, Portland 97201.
authors.forename: M J
authors.initials: MJ
authors.lastname: Silka
authors.forename: J R
authors.initials: JR
authors.lastname: Manwill
authors.forename: J
authors.initials: J
authors.lastname: Kron
authors.forename: J H
authors.initials: JH
authors.lastname: McAnulty
mesh_terms: D001282:Atrial Flutter / Q000150:complications / Q000517:prevention & control; D001919:Bradycardia / Q000150:complications* / Q000628:therapy; D002304:Cardiac Pacing, Artificial / Q000379:methods; D002648:Child; D005260:Female; D006330:Heart Defects, Congenital / Q000150:complications*; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D013610:Tachycardia / Q000150:complications* / Q000517:prevention & control; D013617:Tachycardia, Supraventricular / Q000150:complications / Q000517:prevention & control