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United States Department of Agriculture

Agricultural Research Service

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Research Project: HEART RATE VARIABILITY

Location: Livestock Behavior Research

Project Number: 3602-32000-009-09
Project Type: Specific Cooperative Agreement

Start Date: Aug 28, 2009
End Date: Aug 14, 2010

Objective:
The objective will be to work with Purdue University’s School of Veterinary Medicine to perform the following four tasks: 1. Model sympatho-vagal regulation of cardiac activity in male and female pigs under normal conditions during selective autonomic blockade (atropine and propranolol) and controlled activity to determine the exact location of the spectral frequency bands used to assess heart rate variability. 2. Evaluate any age related changes in sympatho-vagal balance that may influence homeostatic heart rate variability profiles and autonomic reactivity to stressful challenges. 3. Examine sympatho-vagal balance in response to acute and chronic stress. 4. Establish if any specificity exists in sympatho-vagal response to different acute and chronic stress states.

Approach:
Heart rate variability is determined by the animal’s inter-beat interval. Inter-beat interval data will be extracted from electrocardiogram signals, re-sampled, and divided into data sets of 512 beats, then screened for the presence of any ectopic or anomalous beats and evaluated for stationarity necessary for subsequent Fourier analysis. Any spurious beats will be assigned to an error category and corrected according to previously published protocols for addressing the presence of artifacts in inter-beat interval series data. Blood pressure and respiratory data will be handled similarly. Individual epochs of data containing the 512 continuous inter-beat intervals will undergo frequency domain analysis. In doing so the fast Fourier transform will be determined with the sampling interval prefixed at 1 so that resultant frequency data is expressed in cycles per beat, rather than hertz. Power will be established using a Hanning window and the location of individual frequency bands will be confirmed by evaluating shifts in the distribution of spectral power in cardiac, blood pressure, and respiratory spectrums. These frequency ranges will then be applied to evaluate the effects of particular stressors on autonomic regulation of heart rate variability.

Last Modified: 9/20/2014
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