AGE AND SEX-RELATED CHANGES IN HEART-RATE TO VENTILATION COUPLING - IMPLICATIONS FOR RATE-ADAPTIVE PACEMAKER ALGORITHMS

RICKLI, H., ET AL.: Age and Sex Related Changes in Heart Rate to Venti lation Coupling: Implications for Rate Adaptive Pacemaker Algorithms, Minute ventilation (VE) controlled rate adaptive pacemakers determine the paced rare increase during exercise by measuring changes in transt horacic impedance that have been shown to correlate well with VE. To d etermine the normal coupling of hear rate (HR) to VE, this relationshi p was evaluated in 30 younger and 25 older, healthy subjects using pea k cardiopulmonary exercise testing. After determining the anaerobic th reshold (AT), the linear HR to VE slope was determined both below and above the AT. In addition, the entire curve of the HR to VE relationsh ip was assessed by a ''best fit'' regression analysis method. The rela tionship of HR to VE was more often logarithmic in younger as compared to older subjects. The HR to VE slope below the AT was always steeper than above the AT in younger subjects. Females of both age subgroups demonstrated a significantly greater slope below and above the AT. For the appropriate programming of VE controlled, rate responsive pacemak ers, one should fake into consideration age- and sex-specific differen ces in She IIR to VE relationship throughout exercise. Therefore, age- and sex-specific programmable features for rate responsive parameters should be incorporated into pacemakers using VE controlled rate adapt ive algorithms.