INFLUENCE OF AGE ON THE IMMEDIATE CARDIOVASCULAR-RESPONSE TO ORTHOSTATIC MANEUVER

The dynamics of cardiovascular changes following standing up from the supine position were investigated in 41 healthy men aged 20-59 years, classified into three groups: (22-26 years, n = 14), (33-49 years, n = 13) and (51-59 years, n = 14). The protocols consisted of a sequence repeated twice lying down - standing up - lying down. The initial peri od supine was for 20 min and then the subjects remained in each positi on for 8 min. Stroke volume, cardiac output (CO), ejection time ET), p re-ejection period and heart rate (HR) were continuously calculated us ing automated impedance cardiography and electrocardiography. Blood pr essure was measured by the auscultation method. The patterns of HR and haemodynamic orthostatic response were shown to be highly reproducibl e. Most of the indices characterizing the amplitude and rate of cardio vascular changes following standing up showed a tendency towards atten uation with age. However, only the indices of HR, CO and ET responses correlated significantly with age. The strongest relationships with ag e were observed in the sudden increase in HR (r = -0.61, P < 0.01), th e transient increase in CO (r = -0.45, P < 0.001), and the rapid decre ase in ET (r = 0.42, P < 0.01) after standing up. A few indices of HR and haemodynamic response also showed weak correlations with the subje cts' heights and body masses.