Date of Award

Fall 10-31-1994

Document Type


Degree Name

Master of Science in Biomedical Engineering - (M.S.)


Biomedical Engineering Committee

First Advisor

Stanley S. Reisman

Second Advisor

David S. Kristol

Third Advisor

Thomas W. Findley


Spectral analysis of heartrate variability (HRV) provided an estimate of the sympathetic and parasympatheticinfluences on heart rate without drugs or other invasive procedures.However, there are many situations where heart rate changed rapidlyover time and the control of those changes was of considerable interest.Time-frequency analysis was utilized to expand the concept of spectralanalysis of HRV to describe changes in vagal tone and sympatho-vagalbalance as a function of time. As a result the assessment of the autonomicnervous system during rapid changes in heart rate was made.

There were three advantagesto calculating vagal tone and sympatho-vagal balance by using timefrequencyanalysis. First, vagal tone and sympatho-vagal balance were describedas functions of time. Hence, a better understanding was attained aboutautonomic control of rapidly changing signals. Second, the rate of increaseor decrease of vagal tone and sympatho-vagal balance was derived. Theserates were used to determine the integrity of the autonomic system.Third, a mental component affecting vagal tone was suggested. It isanticipated that the effects of anxiety on vagal tone can be revealedusing time-frequency analysis.