Stents Cause Flow Disturbances in
Coronary Arteries: A Study using Laser-Doppler-Anemometry (LDA)
A. Sakurai, D. Liepsch, Th. Schmid, H. Breitfuss, M. Hilber, H.
Berger, S. Schwarzacher
Background: There have been significant
advances in the treatment of atherosclerotic disease in the past few
years. In addition to surgical procedures such as end-to-side bypass
operation, angioplasty with balloon dilatation is now used in
peripheral and coronary arteries. Coronary angioplasty replaces in
many cases a more invasive surgical procedure. This technique however,
though not as invasive as open-heart surgery, also has several
disadvantages, the most common being re-stenosis which occurs in 40%
of the treated patients.
Methods: The fluid dynamic influence of several stents was
tested in transparent silicon rubber models of coronary arteries and
compared with the flow behavior in a healthy coronary artery model.
The flow structure was measured with a one component
laser-Doppler-anemometer. The tested stents were a Carbo stent 3/19, a
Tetra stent and a Carbo stent 2.5/19.
Results: Flow disturbances appeared close to the wires of the
stent near the wall. The Tetra stent creates the 'smoothest'
disturbances.
Conclusion: As these first detailed velocity measurements
demonstrate, the LDA is a good tool for evaluation of stent placement
because in vitro flow conditions and physiological conditions are
always the same. Using this type of model, it is possible to analyze
the flow behavior of stents in detail. This study shows preliminary
results that indicate that slight changes in positioning of the stent
alter the resistance, perhaps contributing significantly to
re-stenosis. In addition to the implantation location, the stent
design, grid configuration, wire thickness and crossing wires are
factors which must be taken into consideration as they modify flow
behavior. This understanding can be very important in reducing
complications after stent implantation.
(CVE. 2005; 10 (1): 69-80)
Key words: stents, LDA measurements, coronary
arteries, elastic models
Prof. Dieter Liepsch, M.D.
FB05
Munich University of Applied Sciences
Lothstr. 34
D-80335 München
Germany
E-mail: Liepsch@fhm.edu
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