Cardiovascular reactivity to a new mental stress test: The maze test

Abstract

The response to the maze test was studied in 31 subjects on no medication, including seven subjects with mild essential hypertension. Beat-by-beat finger blood pressure (BP) was measured with a Finapres device. Pulse interval from which heart rate (HR) was derived was obtained from the BP signal. A period of 5 min baseline was used to define resting levels of systolic BP and HR using 20-s averaged values for the calculation of the 95% confidence limit of the two variables. The average test duration was 10 min. During this period a series of video-displayed mazes had to be solved with easy mazes preceding difficult ones. No subject had been exposed to the test before. The maximal BP elevation associated with the test was 27 mmHg. The HR response averaged 11 beats/min. Significant elevations were observed for half the test duration. No significant relationship between these two responses was observed and some subjects exhibited isolated systolic BP or HR responses. When indices obtained during this active mental stress were compared to resting values, positive correlations were observed. When the resting standard deviation (SD) of systolic BP was higher the systolic response was greater. A similar relationship was observed for HR. In addition, when the systolic BP level at rest was higher, the systolic BP reactivity index was greater. However, systolic BP or HR at baseline were not predictive of the systolic BP or HR responses. This study demonstrates the applicability of a new test to assess cardiovascular reactivity. The main advantage of non-invasive continuous BP measurement with the Finapres is the ability to provide variability indices in addition to the peak responses.

Keywords: autonomic nervous system; blood pressure reactivity; cardiovascular variability; finger blood pressure; heart rate reactivity; mental stress.