Biomedical Engineering Reference
In-Depth Information
Fig. 1.51.
A histogram showing several instances of mean values of the power
spectrum strength of ten heartbeats
position of the frequency (spectrum) analysis is set at auxocardia from the
R-R interval on the electrocardiogram. Although the spectral power by the
MEM is shown as a relative value, it needs to be compared not by a relative
value but by an absolute value. Then, the power spectral density is integrated
on each 100 Hz frequency band. The reason for the 100 Hz interval is that it
seems that the coronary rate of the blood flow in heart diastole is changeable
and unsteady.
The histogram shows several instances of the mean value of the power
spectrum strength of ten heartbeats, as shown in Fig. 1.51. F, A, B, and
others in Fig. 1.51 are the testee, and after B is a testee after a coronary
artery bypass operation. In Fig. 1.51, the abscissa shows the frequency and
theordinateshowsthepowerspectrum.Therowsoftheamplitudestrength
correspond to the number of stenotic sites. By comparing the histogram with
the findings of the coronary angiography that is done independently, it is
found that a vibration with a strong power spectrum is the vibration of the
stenotic murmur.
A histogram showing a preoperative and a postoperative instance of the
mean value of the power spectrum strength of ten heartbeats of the coronary
artery bypass operative patient is shown in Fig. 1.52. B shows the preopera-
tive stage and after B shows the postoperative stage in Fig. 1.52. It is known
that the noise at the stenotic site disappears due to the superfluous vibration,
since the stenosis is canceled by formation of the bypass and the blood flow
increases.
