Prevention of Restenosis in Stent Implantation Using High Intensity Focused Ultrasound
Coronary artery disease is a major cause of both morbidity and mortality in the Western world, and this disease is manifested in introavascular stenosis (narrowing) or occlusion (blocking) due to atherosclerotic plaque. Percutansous transluminal coronary balloon angioplasty followed by insertion of a stent is widely used as the treatment for this disorder. The predominant complication is that patients often develop restenosis. Restenosis is a clinical etymology for describing neointimal formation cause by smooth muscle cell (SMC) proliferation. Our goal is to prove the hypothesis that localized gentle heating with high-intensity focused ultrasound (HIFU) can be used to heat an area around a stent, and to further prove that heating can reduce restenosis. To accomplish the first part of hypothesis, a small acrylic box that is mounted with thermocouples, ultrasound imagining probe, thermal camera, and HIFU transducer has been constructed to hold the tissue (cow's liver). We will use 2 M Hz and 3.5 M HZ single elements transducers to localize a heated region on a tissue. An ultrasound device is used for imaging position of heat deposition by guiding HIFU transducer and collecting RF data from tan ultrasound machine. The camera and thermocouples will record the local temperature variation. With B-mode imaging, we hope to monitor changes in sound speeds caused by changes in temperatures. To accomplish the second part of the hypothesis, a stent will be implanted in a rat's carotid artery and the surrounding tissues are warmed by HIFU. We will test if restenosis is prevented by HIFU heating.
