Baroreflex gain: characterization using autoregressive moving
average analysis .
Patton, David J., John K. Triedman, Michael H. Perrott, Armen A.
Vidian, J. Philip Saul.
Division of Critical Care, Children's Hospital of Alabama,
Birmingham, Alabama 35233, Department of Cardiology, Children's
Hospital, Boston, Massachusetts 02115, Department of Health Sciences
and Technology, Massachusetts Institute of Technology, Cambridge,
Massachusetts 02139
APStracts 2:0488H, 1995.
To study heart rate baroreflex gain, autoregressive moving average
(ARMA) analysis, a multivariate method that allows evaluation of the
dynamic ("beat-to-beat") interactions between changes in
biological signals, was used to evaluate the relations between R-R
interval and arterial blood pressure (BP) during random interval
breathing. Parameters obtained by ARMA analysis of spontaneous
fluctuations in BP and R-R interval in 17 volunteers were used to
model the response of R-R interval to a transient 1 mm Hg increase in
BP; the resulting impulse response and step response curves were
compared to baroreflex gain measured using bolus injections of
phenylephrine (PE) and sodium nitroprusside (NP). Impulse response
curves for the systolic BP - R-R relation showed an early (0-1
second) sharp maximum of 5.5 +/- 4.2 msec/mmHg, which was smaller in
magnitude, but linearly correlated with baroreflex gain derived from
NP (14.5 +/- 9.7 msec/mmHg; r = 0.80, p < 0.002) and PE (31.6
+/- 26.7 msec/mmHg; r = 0.53, p <0.05) injections. A similar
relationship was also found between the 1 beat ARMA step response and
NP injection (r = 0.70, p = 0.01). The integrated step response of
the BP - R-R relation over 6 seconds was 6.4 +/- 4.1 msec/mmHg with
no correlation to baroreflex gain determined by NP (r = 0.33, p =
0.20) or PE (r = - 0.15, p = 0.57). Conclusion: Quantification of
baroreflex gain consistent with other techniques may be achieved by
ARMA analysis without perturbing mean arterial pressure. Correlation
of baroreflex gain obtained by bolus injection to early measures of
baroreflex gain obtained from the ARMA maximum impulse and early step
responses, but not the late step response, suggests that the ARMA
method may provide additional information regarding the frequency
dependent effects of BP on R-R interval.
Received 16 March 1995; accepted in final form 5 September 1995.
APS Manuscript Number H259-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95