血管内超声基础知识

血管内超声基础知识 阜外医院 钱杰 南方会 2008 血管内超声基础知识 一、 血管内超声基础 二、血管内超声和冠脉造影的关系 三、主要适应症 四、什么是 VH 南方会 2008 Rotating Element Drive Shaft Multi-element Array There are two types of imaging systems: Mechanical (rotating transducer) and Electronic Array 南方会 2008 High frequency sound waves echo off vessel walls and are sent back to system System electronics process the signal 南方会 2008 Intimal disease (plaque) is dense and will appear white Media is made of homogeneous smooth muscle cells and does not reflect ultrasound (appears dark) Adventitia has sheets of collagen that reflect a lot of ultrasound (appears white) 南方会 2008 南方会 2008 Calcium Bright echoes (brighter than the adventitia) Obstructs the penetration of ultrasound (acoustic shadowing) only the leading edge is detected and thickness cannot be determined. Results in reverberations - the oscillation of ultrasound between transducer and calcium causing repeating arcs 南方会 2008 80 Superficial Deep Deep Calcium is quantified by measuring the “arc” it encompasses Calcium is classified by its location within the plaque Superficial calcium is closer to the lumen than to the adventitia Deep calcium is closer to the adventitia than to the lumen 南方会 2008 Fibrotic Plaque As bright or brighter than the adventitia (hyperechoic) Majority of atherosclerotic lesions are fibrotic Very dense, fibrous plaques may cause so much acoustic shadowing that they could be misclassified as calcified 南方会 2008 Soft Plaque Not as bright as the adventitia (hypoechoic) “Soft” refers to the low echogenicity, generally due to high lipid content in a mostly cellular lesion. Reduced echodensity may also be due to: necrotic zone within plaque intramural hemorrhage thrombus 南方会 2008 Vulnerable Plaque Fibrous Cap Lipid Core 南方会 2008 Mixed Plaque 南方会 2008 0 1 4mm Example of Thrombus 南方会 2008 Basic Measurements (I) External elastic membrane (EEM) cross sectional area (CSA) = total arterial CSA = media area tracing the boundary between the dark media and the bright adventitia (i.e., the apparent outer edge of the media stripe) Lumen CSA Max and min lumen diameters Stent CSA Max and min stent diameters Plaque+media (P+M) CSA = EEM - Lumen CSA in non-stented lesions = EEM - stent CSA in stented lesions Intimal hyperplasia CSA = Stent - Lumen CSA 南方会 2008 Basic Measurements (II) Eccentricity = maximum/minimum P+M thickness Plaque Burden (=cross-sectional narrowing or %plaque area) = P+M/EEM CSA Remodeling Index = Lesion/Reference EEM CSA Area Stenosis = (Reference - Lesion)/Reference Lumen CSA Arc of calcium Lesion lengths measured using motorized transducer pullback, ideally at 0.5 mm/sec 南方会 2008 Non-stented artery EEMGuidewires IVUS catheter Plaque+media Lumen 南方会 2008 Stented Artery EEM Lumen Stent Guidewire IVUS catheter Plaque+mediaIntimal hyperplasia 南方会 2008 Proximal Reference Lesion Site Distal Reference EEM Lumen P+M Max P+M Thickness Min P+M Thickness Ca+ 南方会 2008 0 3mm 12mm Proximal Reference Lesion Site Distal Reference EEM CSA = 20.4 Lumen CSA = 9.7 Max lumen diam = 3.7 MLD = 3.1 P+M CSA = 10.7 Eccentricity = 1.0/0.3 Plaque burden = 0.52 Arc of Ca = 60 EEM CSA = 21.6 Lumen CSA = 4.5 Max lumen diam = 32.8 MLD = 2.3 P+M CSA = 17.1 Eccentricity = 3.0/0.1 Plaque burden = 0.79 EEM CSA = 13.3 Lumen CSA = 8.9 Max lumen diam = 3.6 MLD = 3.0 P+M CSA = 4.4 Eccentricity = 0.6/0.2 Plaque burden = 0.33 Average Reference EEM CSA = 16.9 Remodeling Index = 1.3 Average Reference Lumen CSA = 9.3 Area Stenosis = 52% 南方会 2008 In-Stent Restenosis In-stent intimal hyperplasia (IH) often appears with a very low echogenicity Could be less echogenic than the blood speckle Appropriate system settings are critical to visualize IH (do not “black out” center) 南方会 2008 血管内超声基础知识 一、血管内超声基础 二、 血管内超声和冠脉造影的关系 三、主要适应症 四、什么是 VH 南方会 2008 Limitations of Coronary Angiography Focal Disease 50% Lesion 50% LesionDiffuse Disease Angiogram Silhouette 南方会 2008 Angiographically Silent Disease In 884 native coronary arteries, the plaque burden in the angiographically “normal” reference segment was 5113% Mintz GS, et al. J Am Coll Cardiol 1995;25:1479-1485 南方会 2008 Coronary Remodeling Hypothesis Compenatory Expansion Maintains Consistant Lumen Expansion Overcome: Lumen Narrows Normal Vessel Minimal CAD Moderate CAD Severe CAD 南方会 2008 Proximal reference Lesion Distal reference Intermediate remodeling Negative remodeling Positive remodeling Nishioka. JACC 1996; 27:1571-1576 Dicotomous Classification of Remodeling 南方会 2008 Irregular Plaque / Irregular Lumen A Cross-section RAO View LAO View B C 南方会 2008 IVUS EEM CSA = 22.7mm2 Lumen CSA = 16.6mm2 Mean lumen diameter = 4.6mm QCA 9F guiding catheter Reference diameter = 3.12mm 南方会 2008 血管内超声基础知识 一、血管内超声基础 二、血管内超声和冠脉造影的关系 三、 主要适应症 四、什么是 VH 南方会 2008 Validation of IVUS Assessment of Ischemia Producing Stenosis (Doppler FloWire and SPECT) IVUS MLA 4.0mm2 IVUS MLA 4.0mm2 (%) Cypher 5.0* sensitivity specificity 0 10 20 30 40 50 60 70 80 90 100 3.54.04.55.05.56.0 7.07.5 8.08.5 F/U MLA 4.0mm2 (%) Bare Metal Stents 6.5*Minimum stent area (mm2) Minimum stent area (mm2) (Sonoda et al. J Am Coll Cardiol 2004;43:1959-63) *predictive value=56% *predictive value=90% 南方会 2008 Predictors of angiographic restenosis in 550 pts with 670 native artery lesions treated with Cypher stents 0 20 40 60 80 100 0 20 40 60 80 100 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 Angiographic restenosis (%)Angiographic restenosis (%) IVUS MSA (mm2) 10152025303540455560657075 IVUS total stent length (mm) 40mm 17.7% 8.6%(Hong et al. unpublished) 南方会 2008 Comparison of IVUS-measured minimum stent diameter (MSD) and minimum stent area (MSA) with the predicted measurements from Cordis (Cypher in yellow, n=133) and BSC (Taxus in red, n=67). DES achieve an average of only 75% of the predicted MSD (66% of MSA) IVUS Measured MSA (mm 2) Predicted MSA (mm2) IVUS Measured MSD (mm) Predicted MSD (mm) 24% 南方会 2008 Peri-Stent Haziness: Double Lumen 南方会 2008 Peri-Stent Haziness: Plaque Burden Two Overlapping Stents Hazy Segment 南方会 2008 Peri-Stent Haziness: Calcification Stent 南方会 2008 Peri-Stent Injury: Plaque Tear Ultrasound Site Stent 南方会 20