Automated In Vivo Platform for the Discovery of Functional Food Treatments of Hypercholesterolemia
Figure 4
Waveform Analysis Methodologies.
Volume change over time (top) calculated from area change as outlined in figure 3. Briefl, area waveform values were input into the equation, C = (6.8×10−4) * A + 46 from which volume over the heartbeat was calculated according to the equation V = (4/3)**A*C where A is the area of the ventricle during the beat cycle and C is the radius in the Z-direction. A. In the Fourier framework (left), a waveform is transformed to Fourier space in order to extract the amplitude and frequency (f) of the wave. In this case, these values represent ½ of the stroke volume (SV) and theheart rate (HR) respectively. From these parameters, we calculate cardiac output (CO) and ejection fraction (EF). A representative waveform with average diastolic and systolic volumes as calculated by Fourier is presented (bottom left). Notice that thedistance between diastole and systole compared to segmentation approach B. In th segmentation approach (right), the original waveform is transformed to Fourier space. The frequency of the peak of the transform is extracted to determine the period (T) of the waveform which is then utilized as a baseline value on which to base the size of segment for analysis. The algorithm measures maximum and minimum values within each segmen (which is sized at 1.1× T in order to increase the liklihood of capturing the maximum and minimum values) traversing the waveform. Stroke volume is calculated as the mean maximum value – mean minimum value and is represented as average diastole and average systole (bottom right).