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Temporal changes in hemodynamic
reactivity
before, during and after a real-life stressor
Ydwine J. Zanstra
Professor Derek W. Johnston
Health Psychology Group
University of Aberdeen
Cardiovascular reactivity
• Psychological stress may play a role in
the etiology of cardiovascular disease
• Link between stressor appraisals and
exaggerated or maladaptive
cardiovascular reaction patterns
Cardiovascular reactivity:
hemodynamic reaction patterns
Research into the pathogenic role of
stress in the etiology of cardiovascular
disease and hypertension will benefit
from examining hemodynamic reaction
patterns
(Ottaviani et al., 2006; Sherwood &
Turner, 1995)
Cardiovascular reactivity:
hemodynamic reaction patterns
hemodynamic reaction patterns :
changes in the parameters underlying
blood pressure:
Blood Pressure =
Cardiac Output *Total Peripheral Resistance
Cardiovascular reactivity:
hemodynamic reaction patterns
Hemodynamic changes in response to a stressor are
typically examined in the laboratory
• threat appraisals have been shown to be associated
with increased Total Peripheral Resistance
• challenge appraisals were associated with increases
in Cardiac Output.
(e.g. Tomaka et al., 1993, 1997; Blascovich & Tomaka,
1996)
Objective
to obtain ambulatory measures of
changes in hemodynamic variables :
• Cardiac Output (CO),
• Total Peripheral Resistance (TPR),
• Mean Blood Pressure (MBP) and
• Heart Rate (HR)
in response to a real-life stressor
Methods
Participants: 12 men aged 20-27.
Within-subjects design:
• Ambulatory blood pressure
• measured during before and after
performance of a presentation:
– anticipation, stressor, recovery
Methods: ambulatory blood pressure
Portapres
Ambulatory non-invasive
blood pressure measurements:
Consists of:
•Two finger cuffs
•Belt (pump, battery and memory card)
•Height correction system
Records:
•Continuous measurement
•Sampling rate = 100 Hz
Hemodynamic variables (e.g. Cardiac Output, Total Peripheral
Resistance) can be derived from blood pressure waveform
Analysis
•Heart Rate values were derived from the blood pressure waveform.
•Modelflow analysis was used to derive beat-to-beat values for Total
Peripheral Resistance and Cardiac Output.
•After artefact correction, one-minute means were calculated for all
variables.
•T-tests were used to compare stressor levels to those during the
anticipation and recovery periods.
•Repeated measures analysis was performed on all variables for the 52
minutes preceding the stressor, (anticipation) and the 45 minutes
after the stressor (recovery).
Results
T-tests:
1. anticipation vs. stressor
the mean of the of the first two minutes of the stressor compared to
the last two minutes of the anticipatory period
2. stressor vs. recovery
the mean of the of the first two minutes of the stressor compared to
the first two minutes of the recovery period
Significant effects in Mean Blood Pressure only:
•
anticipation vs. stressor was significant (t(11) = 2.57, P = .026)
•
stressor vs. recovery approached significance (t(11) = -1.93, P =
.080)
Results
anticipation (last two minutes), stressor (first two minutes), and recovery (first two minutes)
Results
anticipation (last two minutes), stressor (first two minutes), and recovery (first two minutes)
Results:
anticipation and recovery
Repeated measures analysis of; analysis of changes during
anticipation and changes during recovery:
Heart Rate and Mean Blood Pressure
Anticipation:
significant, upward linear trends in Mean Blood Pressure
(F(1,11)=6.21, P=.03)
and Heart Rate (F(1,11)= 8.56, P=.014)
Recovery:
Mean Blood Pressure values decrease over time (n.s.)
Heart Rate decreased during recovery, linear trend
approached significance (F(1,11)= 3.43, P=.087).
Results:
anticipation and recovery
Anticipation:
significant, upward linear trends
in Mean Blood Pressure and
Heart Rate
Recovery:
• Mean Blood Pressure values
decrease over time (n.s.)
• Heart Rate decreased during
recovery; linear trend
approached significance
Mean Blood Pressure and Heart Rate as a
function of time during anticipation and recovery
Results:
anticipation and recovery
Repeated Measures analysis of changes during anticipation and
changes during recovery:
Cardiac Output and Total Peripheral Resistance:
Anticipation:
Cardiac Output showed a quadratic trend approaching
significance (F(1,11)=3.36, P=.094). Values increased
initially and decreased just prior to the start of the
stressor.
Total Peripheral Resistance showed a quadratic trend that
approached significance (F(1,11)=3.49, P=0.088). Initial
decrease was followed by an increase
Recovery: no significant results
Results:
anticipation and recovery
Anticipation:
Cardiac Output
• quadratic trend approaching
significance. Values increased
initially and decreased just prior
to the start of the stressor.
Total Peripheral Resistance
• quadratic trend that approached
significance: Initial decrease
was followed by an increase
Recovery: no significant results
Cardiac Output and Total Peripheral Resistance
as a function of time during anticipation and
recovery
Summary of main findings
• Both heart rate and mean blood pressure increased
initially.
• The anticipatory increase in mean blood pressure
appears to be at first mediated by early rises in
Cardiac Output.
• However, just before the start of the stressor, Cardiac
Output decreases.
• Total Peripheral Resistance continues to rise
throughout the anticipatory period and appears to be
increasingly responsible for the continuing rise in
mean blood pressure.
• Changes during recovery were nonsignificant
Discussion
1. Changes in hemodynamic parameters
over time can be measured in real-life
2. Linear increases in blood pressure may
be mediated by more complicated
patterns of change in hemodynamic
parameters
3. Future analysis will focus on the
relationship of hemodynamic reaction
patterns with stressor appraisal
References
•
•
•
•
•
Blascovich, J., & Tomaka, J. (1996). The biopsychosocial model of
arousal regulation. Advances in experimental social psychology, 28, 151
Ottaviani, C., Shapiro, D., Goldstein, I. B., James, J. E., & Weiss, R.
(2006). Hemodynamic profile, compensation deficit, and ambulatory
blood pressure. Psychophysiology, 43(1), 46-56.
Sherwood, A., & Turner, J. R. (1995). Hemodynamic responses during
psychological stress: Implications for studying disease processes.
International Journal of Behavioral Medicine, 2(3), 193-218.
Tomaka, J., Blascovich, J., Kelsey, R. M., & Leitten, C. L. (1993).
Subjective, physiological and behavioural effects of threat and
challenge appraisal. Journal of Personality and Social Psychology,
65(2), 248-260
Tomaka, J., Blascovich, J., Kibler, J., & Ernst, J. M. (1997). Cognitive
and Physiological Antecedents of Threat and Challenge Appraisal.
Journal of Personality and Social Psychology, 73(1), 63-72.
Temporal changes in hemodynamic
reactivity
before, during and after a real-life stressor
Ydwine J. Zanstra
Professor Derek W. Johnston
Health Psychology Group
University of Aberdeen
Artefact correction
The artefact detection and correction procedure
was carried out using CARSPAN software
(Mulder, 1988):
•moving averages were calculated for time
windows of 60 seconds
•a value was identified as an artefact if it
exceeds a confidence interval of +/- 4 S.D.’s
around that moving average.
•Artefact correction involved linear interpolation
between two preceding and two successive
values
Modelflow Algorithms
For computing hemodynamic parameters
MAP =CO*TPR
Given:
• MAP (Mean Arterial Pressure)
• HR (Heart Rate)
Unknown:
• SV (Stroke Volume)
• CO (Cardiac Output)
• TPR (Total Peripheral Resistance)
1. SV = Asys*/Zao**
2. CO (l/min) = SV (l) * HR (beats/min)
3. TPR (dyne-s · cm-5) = (MAP (mmHg) / CO (l/min)) x 80
*=area under the systolic portion of the pressure wave
**=characteristic impedance of the aorta