The Effects of Aging on AV Nodal Recovery Properties

Abstract

The purpose of this study was to assess the changes of AV nodal recovery properties with aging. Although in children and young adults it was found that there were age dependent changes in their AV nodal recovery properties, in the older population this information was not available. In 92 subjects (aged 16-92 years) without AV nodal disease or dual AV nodal pathway physiology, their AV nodal recovery curves were studied by delivering premature atrial extrastimuli coupled to basic atrial beats during cardiac electrophysiological study. Data were analyzed using linear regression and curve-fitting techniques. Patients were grouped by age, group I < 40 years (n = 33), group II 40-59 years (n = 26), and group III > 60 years (n = 33). The results showed that the AV nodal recovery curve did not change significantly in the aging process except that the AV nodal effective refractory period had a positive correlation with increasing age. The latter was significantly increased in group III when compared to group I or group II. For this parameter, when patients whose AV nodal refractory period was limited by the atrial refractory period were excluded, there was still a statistically significant increase in group III compared to group II (P < 0.05): group I (n = 27): 202+/-42 ms; group II (n = 17): 197+/-26 ms; and group III (n = 17): 224+/-46 ms. The results suggest that the AV nodal recovery curve remains unchanged once it reaches adulthood, with the exception that the nodal effective refractory period becomes slightly longer after age 60.

Simultaneous Dual Fast and Slow Pathway Conduction upon Induction of Typical Atrioventricular Nodal Reentrant Tachycardia: Electrophysiologic Characteristics in a Series of Patients

“…It is well known that AV node conduction changes progressively with aging 20 . A slowing of AVNRT cycle length and an increase of AVN antegrade refractory period, of Wenchebach cycle length, and of P–R interval have been described, together with a decrease in overt dual AVN physiology pattern at EP study 20–22 .…”

“…On the basis of AVNRT induction modalities at EP study, two study groups were extrapolated: seven patients (group I: 6 females, 1 male; mean age 65.2 ± 3.8 years, range 60–72 years) who showed AVNRT induced through SDNC, and 118 controls aged 60 years or over (group II: 60 females, 58 males; mean age 68.4 ± 6.8 years, range 60–88 years) with AVNRT induced without SDNC. Such an age limit for recruiting controls was decided in order to have an overall matching by age with SDNC patients, since aging process consistently modifies AV node conduction properties 20–22 . Because of the presence of some very old control patients, group II controls were further subdivided into two subgroups: subgroup A, which consisted of 94 patients, aged 60–75 years (mean 65.8 ± 3.9 years; 53 females, 41 males); subgroup B, which consisted of 24 patients, aged more than 75 years (mean 80.3 ± 3.3 years; 8 females, 16 males).…”

Bradyarrhythmias in the Elderly

“…7 The impact of these pathoanatomic changes on AV node function is uncertain; in fact, one small clinical study found that refractory periods of the AV node prolonged only slightly once adulthood was reached. 8 However, as discussed later, large population studies have consistently demonstrated progressive delay in AV conduction with age. It may be that aging has different effects on refractoriness and conduction velocity properties of the AV conduction system.…”

Arrhythmias in Patients ≥80 Years of Age

“…In addition, pre-clinical studies in rabbits have shown an aging-related slowdown of electrical conduction velocity throughout the His-Purkinje network (8), which is manifested in humans by prolongation of the HV interval. Kuo et al (9) showed that the atrioventricular (AV) nodal recovery curve remains unchanged once one reaches adulthood, whereas the AV nodal effective refractory period becomes slightly longer after age 60 years (9). …”