[Cardiovascular responses to passive and active orthostatism in healthy subjects, in relation to age]

Changes in heart rate induced by inclining an orthostatic table to 30 degrees and 60 degrees and by standing was studied in 200/healthy volunteers of either sex. Study subjects were divided in eight ten-year age groups, from 16 to 97 years. The 56-65 year age group was the youngest group to develop systolic orthostatic hypotension. This response occurred in 4% of subjects aged 56-65 years and became increasingly prevalent from one age group to the next (25%, 36% and 44%). In some patient, the fall in systolic BP reached 70 mmHg. Systolic hypotension occurred in some patients at 30 degrees but in most cases developed only at 60 degrees. No significant difference was found between the falls in SBP seen at 60 degrees and during active standing (90 degrees), indicating that muscular activity does not play a major role in BP regulation. Diastolic hypotension was less common and was mainly seen in patients above 75 (20%) who also had systolic hypotension. Orthostatism was responsible for tachycardia but this response became increasingly less common beyond 55 years of age (60, 60, 52 and 36% in the four age groups above 55). This reflects increasing loss of sensitivity of the baroreflex with advancing age. These date are useful for comparing the age-specific effects of disease states (e.g. diabetes mellius, alcohol abuse) or treatments (psychoactive drugs, antihypertensive agents).