SPECTRAL-ANALYSIS OF STRESS-INDUCED CHANGE IN BLOOD-PRESSURE AND HEART-RATE IN NORMOTENSIVE SUBJECTS

Changes in spectral analysis of the variability in systolic blood pres sure (SBP) and heart rate (HR) were investigated in 12 normotensive vo lunteers during a well-standardized stress test. BP was measured indir ectly from the finger by a noninvasive device (Finapres). The stress t est was a computerized version of the Stroop color word conflict test (CWT). The influences of acute (single dose) beta(1)-selective blockad e by bisoprolol or angiotensin-converting enzyme (ACE) inhibition by l isinopril were analyzed by a double-blind placebo-controlled trial. Du ring the placebo phase, the efficiency of the stress test was confirme d by a significant increase in SBP (25 +/- 11%), HR (36 +/- 23%), and plasma concentrations of epinephrine (Epi, 54 +/- 37%) and norepinephr ine (NE, 27 +/- 35%). Stress induced a significant increase in the amp litude of SBP and HR oscillations in the medium-frequency band (MF, 70 - to 140-mHz range), which corresponds to the Mayer waves (27 +/- 32 a nd 42 +/- 43%, respectively for SBP-MF and HR-MF). The stress-induced increase in NE correlated significantly with the increase in HR (r = 0 .68, p < 0.05). The stress-induced increase in SBP-MF correlated signi ficantly with the increase in Epi (r = 0.69, p < 0.05) and in HR-MF (r = 0.69, p < 0.05). A significant decrease in SBP-MF at rest was obser ved with a single oral (p.o.) dose of bisoprolol, but not of lisinopri l. As a noninvasive method, spectral analysis of the variability in SB P and HR may be of benefit in stress-induced modifications of the auto nomic nervous system.