A miniature sound probe (transducer) capable of producing high-frequency sound waves (40-60mHz) mounted on the tip of a coronary catheter is advanced into the coronary artery.<\/p>\n This produces a detailed analysis of the internal layers of the coronary artery, providing important information to your interventional cardiologist that will guide further management.<\/p>\n <\/strong>Coronary Angiography is the gold standard in the diagnosis and assessment of coronary artery disease but it has several limitations:<\/p>\n <\/strong><\/p>\n<\/th>\n \u51a0\u72b6\u52a8\u8109\u9020\u5f71<\/strong><\/p>\n<\/th>\n IVUS<\/strong><\/p>\n<\/th>\n<\/tr>\n<\/thead>\n\n Normal vs Diffuse disease<\/strong><\/p>\n<\/td>\n Concentric and Eccentric plaques<\/strong><\/p>\n<\/td>\n Calcification of coronary vessels<\/strong><\/p>\n<\/td>\n Dissection<\/strong><\/p>\n<\/td>\n Thrombus<\/strong><\/p>\n<\/td>\n Stent sizing<\/strong><\/p>\n<\/td>\n Stent expansion and apposition<\/strong><\/p>\n<\/td>\n IVUS is thus highly favored by expert interventional cardiologists as an adjunctive tool during coronary angiography and angioplasty.<\/p>\n Eccentric plaques<\/strong> are distributed non-circumferentially in the vessel; this makes the assessment of disease by angiography especially prone to underestimation or overestimation depending on the angle of view.<\/p>\n Calcium<\/strong> is indicated by very bright areas with acoustic shadowing that blocks out the image behind; this shadowing occurs because the high density of calcium dampens the ultrasound echo.<\/p>\n Fibrous plaques<\/strong> have an intermediate echogenicity between soft (echolucent) atheromas and highly echogenic calcific plaques. They exhibit little or no acoustic shadowing.<\/p>\n Coronary angioplasty <\/strong>if performed, is usually straightforward as the stent will have minimal\/no difficulty expanding the lumen of the narrowed blockage.<\/p>\n Calcium<\/strong> is indicated by very bright areas with acoustic shadowing that blocks out the image behind it. The shadowing occurs because the high density of calcium prevents the ultrasound from passing through.<\/p>\n IVUS<\/strong> is able to pick up calcium more accurately than coronary angiography alone.<\/p>\n \u51a0\u72b6\u52a8\u8109\u9020\u5f71<\/strong> if performed is less straightforward and may require plaque modification using rotablation or shockwave lithiotripsy before stenting can be performed optimally.<\/p>\n Stent under-expansion<\/strong> has been strongly associated with restenosis (renarrowing of the stent) and stent thrombosis (clot formation within the stent)1<\/sup>.<\/p>\n IVUS-guided coronary angioplasty<\/strong> has been showed to reduce the need for repeat stenting procedures and risk of morbidity and mortality associated with stent thrombosis.<\/p>\n![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/ivus_probe.jpg\" "\\"ivus_probe\\"")
<\/span><\/p>\nWhat is the clinical utility of IVUS?<\/h2>\n
\n\n
\n \n \n \n \n \n Tends to underestimate degree of narrowing in diffuse disease or vessels with positive remodelling<\/td>\n Helps you distinguish normal from abnormal vessels and find the location of disease in patients with a normal angiogram.<\/td>\n<\/tr>\n \n \n Must rely on \u201ceyeball\u201d estimate. Assessment of eccentric plaque lesion size especially prone to error based on angle of view.<\/td>\n Helps you get an accurate lumen area to determine lesion significance and stent size.<\/td>\n<\/tr>\n \n \n Less sensitive than IVUS for detecting calcium<\/td>\n Makes the presence of calcium clear, helping to identify lesions that need pre-treatment.<\/td>\n<\/tr>\n \n \n Cannot determine where the dissection begins.<\/td>\n Dissections can be accurately defined.<\/td>\n<\/tr>\n \n \n Difficult to determine<\/td>\n Thrombus can be accurately defined.<\/td>\n<\/tr>\n \n \n Must rely on \u201ceyeball\u201d estimate<\/td>\n Enables you to make lumen and reference vessel measurements that can be used when selecting stent size.<\/td>\n<\/tr>\n \n \n Cannot see the vessel wall to verify optimal placement.<\/td>\n User-defined cross-sectional area measurements and views allow verification and documentation of stent placement.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n \n
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In summary, IVUS helps to:<\/h2>\n<\/p>\n
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<\/strong>Rotational IVUS Image interpretation<\/h2>\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/frictional_flow_study1.jpg\" "\\"frictional_flow_study1\\"")
<\/span><\/p>\n\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/normal_coronary_vessel.jpg\" "\\"normal_coronary_vessel\\"")
<\/span><\/p>\n\n
\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/concentric_mixed_plaque.jpg\" "\\"concentric_mixed_plaque\\"")
<\/span><\/p>\nInformation obtainable from IVUS <\/h4>\n
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Utility of the Minimal Lumen Area (MLA)<\/h4>\n
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![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/citations.jpg\" "\\"citations\\"")
<\/span><\/p>\n\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/eccentric_mixed_plaque.jpg\" "\\"eccentric_mixed_plaque\\"")
<\/span><\/p>\n\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/fibrous_plaque.jpg\" "\\"fibrous_plaque\\"")
<\/span><\/p>\n\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/calcified_plaque.jpg\" "\\"calcified_plaque\\"")
<\/span><\/p>\n\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/underexpanded_stent.jpg\" "\\"underexpanded_stent\\"")
<\/span><\/p>\n![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/citation2.jpg\" "\\"citation2\\"")
<\/span><\/p>\n\n
a. Coronary Dissection<\/h4>\n
![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/coronary_dissection.jpg\" "\\"coronary_dissection\\"")
<\/span><\/p>\n![\"\"](\"\/\/www.sozocardiology.com\/wp-content\/uploads\/2020\/06\/intralumial_thrombus.jpg\" "\\"intralumial_thrombus\\"")
<\/span><\/p>\n