Biomedical Engineering Reference
In-Depth Information
Acknowledgment.
This research was supported by the Japan Society for
the Promotion of Science “Research for the Future” program.
1.8
A New Technology for Detecting
Coronary Artery Disease
1.8.1
Coronary Artery Disease
Coronary artery disease is life threatening and happens due to the gradual
progression of coronary artery stenosis. For the prevention of coronary artery
disease, the detection and suppression of coronary artery stenosis is of most
importance. In general, diagnosis of coronary artery disease is invasively done
by coronary arteriography, following the onset of symptoms of coronary ar-
tery disease. A reliable noninvasive method is required for the early detection
of coronary artery disease and for repeated monitoring of the flow state of
the coronary artery. It is reported that arterial narrowing as small as 25%
can produce post-stenotic turbulence [76-78]. The related auditory response
can be used to detect lesions of the coronary artery [78]. However, occlusions
larger than 95% may not produce noises, since in such instances blood flow is
drastically reduced. In spite of an ongoing effort to develop an instrument to
noninvasively detect coronary disease, a noninvasively detecting device that
is commercially available for clinical use has not yet been developed. Be-
cause coronary artery disease is one of the major causes of mortality in the
developed world, the prompt dissemination of research results is critical to
advancing patient care. In particular, better methods for identifying asym-
ptomatic persons at high risk of developing future clinical coronary artery
disease are needed, so that we can target preventive monitoring methods,
such as noninvasive examination, at those most likely to benefit from such
examinations in a cost-effective fashion.
We have developed a new technology of a noninvasive laser phonocardio-
graph, which is made up of a noncontact ultra-supersensitivity and small mass
laser sensor with low noise and a high gain amplifier and signal processing
approach using a maximum entropy method [79-81].
1.8.2
The Detection of Subclinical Coronary Stenosis
For the prevention of coronary artery disease, the detection and suppression
of subclinical coronary artery stenosis induced by subclinical atherosclerosis is
of most importance. Methods for detecting subclinical atherosclerosis can be
grouped into physiological and anatomical methods. Physiological methods
require some functional impairment of blood flow or another arterial vascular
function. Because acute coronary events are frequently caused by lesions that
represent less than 75% stenosis of the vessel, the goal in identifying persons
at high risk of coronary events is not to identify those with flow-limiting coro-
nary stenoses (as does stress testing) but, rather, to identify persons who are
