Age-dependent influence of heart rate on Doppler indexes of left ventricular filling.

BACKGROUND AND OBJECTIVE

The Doppler indexes of left ventricular filling are related to age and heart rate. The aim of this study was to assess whether the influences of heart rate and age interactions (that is, whether the effect of heart rate on the Doppler indexes) is modified by age.

SUBJECTS AND METHODS

The effects of atropine-induced heart rate increases on the transmitral velocities were compared in 10 younger healthy subjects aged 26-38 years and 12 older healthy subjects aged 50-67 years.

RESULTS

With a comparable total rise in heart rate (on average 20 beats min-1), the peak early diastolic velocity decreased likewise in both groups (from 66 +/- 9 to 57 +/- 9 cm s-1 in the younger age group and from 58 +/- 15 to 47 +/- 13 cm s-1 in the older age group). The peak atrial velocity remained unaltered in the older group (53 +/- 16 vs. 52 +/- 14 cm s-1) but rose from 33 +/- 6 to 44 +/- 12 cm s-1 in the younger (P = 0.02). The early-to-atrial peak velocity ratio decreased from 1.2 +/- 0.6 to 1.0 +/- 0.4 cm s-1 in the older subjects and from 2.0 +/- 0.5 to 1.4 +/- 0.5 cm s-1 in the younger subjects (P = 0.01). Changes in the other Doppler indexes were similar in both groups.

CONCLUSIONS

The effect of heart rate on certain Doppler indexes of left ventricular filling is age-dependent. The peak velocity ratio cannot be interpreted without adjusting for heart rate in younger subjects, whilst in older people heart rate variation is of less importance.