Lezione 3 Tronchi Sovraortici

Transcription

1 CORSO DI CERTIFICAZIONE DI COMPETENZA in ECOGRAFIA VASCOLARE GENERALE Lezione 3 Tronchi Sovraortici Settore formazione : Direttore: Paolo G. Pino Marco Campana, Antonella Moreo, Fausto Rigo, Ketty Savino

2 Overview Epidemiology Clinical trials Anatomy Hemodynamic flow patterns Assessment of stenosis Classification of disease Video case presentation Dipartimento Cardio-Toracico - Università di Pisa

3 Causes of Stroke: Cerebrovascular Atherosclerosis 85% Infarction 15% Hemorrhage - Intracerebral - Subarachnoid 60% Cerebrovascular atherosclerosis - Stenosis (flow reduction) - Ulcerated plaque (artery-to-artery emboli) 20% Penetrating artery disease (lacunes) 15% Cardiogenic embolism Cardiac and Thoracic Department - University of Pisa 5% Other, unusual causes

4 ARIC Atherosclerosis Risk in Communities patients - Age: range years - Carotid plaque prevalence: 34% - Gender: male > female R. Li; Stroke patients (Northern Italy) - Age: range years -Carotid plaque prevalence: 25,4% M - 26,4% F Carotid plaque prevalence: 30,8% M - 21,9% F Patients: years P. Prati; Stroke 1992

5 ASYMPTOMATIC CAROTID LESIONS IN 755 SUBJECTS IN RELATION WITH A SINGLE NORMALS FINDINGS (%) IMT (%) A.C.P. (%) RF R.F R.F * 14.7 * HYPERTENS * * NIDDM * 16.7 * HYPER-C * FAMILY H. CVD HYPER-TG SMOKING * 0 OBESITY IMT+ACP (%) * 65.5 * 41.7 * 26.6 * * 4.7 Novo S.: Adv. Vasc. Pathol. 1997; Excerpta Medica, Amsterdam 1997: 36-46

6 Prevalence and outcome of asymptomatic carotid stenosis: a population-based ultrasonographic study 500 volunteers 200 men and 300 female Without signs and symptoms of cerebrovascular disease aged years The prevalence of asymptomatic carotid stenosis of 50% or greater was 6.4%. Severe carotid stenosis was detected in only 0.4% of the subjects examined. European Journal of Neurology

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8 Intrinsic risk of embologenic carotid stenosis 13.1% major ipsilateral stroke in 2 years in NASCET (about 6.5%/yr) - 13%/yr for ANY ipsilateral stroke NASCET 16.2% ANY ipsilateral stroke in 3 years in ECST (about 5.4%/yr) MOST strokes are within first year of signal event. Cardiac and Thoracic Department - University of Pisa

9 EPIDEMIOLOGICAL DATA: Conclusion 1) High prevalence of Carotid Artery plaques 2) Lower prevalence of carotid Stenosis 50% - (6.4%) 3) High mortality in patients with symptomatic carotid stenosis 4) High risk for embologenic carotid stenosis Cardiac and Thoracic Department - University of Pisa

10 THERAPEUTIC OPTIONS IN PATIENTS WITH CAROTID ARTERY DISEASE 1. Medical Therapy 2. Surgical Therapy 3. Interventional Therapy Cardiac and Thoracic Department - University of Pisa

11 THERAPEUTIC OPTIONS IN PATIENTS WITH CAROTID ARTERY DISEASE NASCET (North American Symptomatic Carotid Endarterectomy Trial) - Carotid Stenosis > 70% - TEA stroke risk of 17% at 2 years ECST (European Carotid Surgery Trials) - Symptomatic patients with stenosis > 70% - Stroke incidence 14,9% (Surgery) (Medical Treatment) ACAS (Asymptomatic Carotid Atherosclerosis Study) - Carotid Stenosis > 60% - TEA stroke risk of 5.8% at 5 years Cardiac and Thoracic Department - University of Pisa

12 Intrinsic risk of embologenic carotid stenosis 13.1% major ipsilateral stroke in 2 years in NASCET (about 6.5%/yr) - 13%/yr for ANY ipsilateral stroke NASCET 16.2% ANY ipsilateral stroke in 3 years in ECST (about 5.4%/yr) MOST strokes are within first year of signal event Risk is directly proportional to degree of stenosis!! - UNSTABLE PLAQUE IS VULNERABLE TO FLOW! Cardiac and Thoracic Department - University of Pisa

13 Overview Epidemiology Clinical trials Anatomy Hemodynamic flow patterns Assessment of stenosis Classification of disease Video case presentation Dipartimento Cardio-Toracico - Università di Pisa

14 Anatomy Common Carotid Artery Right CCA originates from brachiocephalic Artery Left CCA originates from Aorta Difficult to image origin of left CCA

15 CAROTID BULB CCA bifurcates at upper level of thyroid cartilage (C4) into internal and external carotid arteries Fusiform dilatation Unique flow patterns Exact location varies among patients Usually symmetric within a patient Anatomy

16 Anatomy INTERNAL CAROTID ARTERY Supplies the brain No branches in the neck Inside the skull makes S shaped curve called the carotid siphon First major branch is the ophthalmic artery (eye) Bifurcates into middle and anterior cerebral arteries in the circle of Willis

17 Anatomy EXTERNAL CAROTID ARTERY Supplies the muscle and skin of the face and scalp Lies anterior and medial to ICA Numerous branches in the neck May provide collateral supply to brain with ICA stenosis/occlusion

18 Anatomy

19 Overview Epidemiology Clinical trials Anatomy Hemodynamic flow patterns Assessment of stenosis Classification of disease Video case presentation Dipartimento Cardio-Toracico - Università di Pisa

20 Flow Patterns Types of flow Laminar Disturbed Turbulent Major determinants Geometry of the arterial system Resistance to flow offered by the tissue/organ

21 Flow Patterns : Geometry Helical flow and boundary flow separation occur at bifurcations

22 Flow Patterns : Resistance LOW RESISTANCE TO FLOW Brain, liver, kidney End diastolic flow always above zero HIGH RESISTANCE TO FLOW Muscles, intestine Resistance dependant on metabolic activity Triphasic response (forward-reverseforward flow) End diastolic flow near zero

23 Flow Patterns : Normal Carotid Artery ICA : brain is low resistance organ ECA : facial muscles show variable resistance CCA : supplies brain (70-80%) and facial muscles

24 Normal Flow Patterns

25 Normal Flow Pattern : CCA Mid CCA 2cm from bifurcation EDV above zero baseline Distal CCA Just proximal to bifurcation CCA begins to dilate Peak systolic velocity decreases EDV increases Normal flow disturbances

26 Normal Flow Pattern : ECA Supplies face and scalp, not a source of cerebral emboli Characteristics of high resistance vessel Peak systolic velocity higher than ICA Rapid systolic acceleration Prominent dichrotic wave in late systole or early diastole EDV near zero baseline

27 Normal Flow Pattern : Carotid Bulb and Proximal ICA Complex flow patterns due to dilatation and bifurcation Anatomic changes create boundary layer separation and helical flows Unidirectional flow near flow divider Transient flow reversal near outer wall When present, these confirm normal carotid bulb

28 Normal Flow Pattern : Mid ICA Low resistance flow pattern EDV above zero baseline Peak systolic velocity may be higher than the proximal ICA due to smaller diameter Normal flow disturbances from carotid bulb may travel into the mid ICA

29 Vessel Identification : CCA Proximal CCA Courses toward skin surface then curves parallel Curve creates normal flow disturbances Origins often difficult to image (esp left CCA) Mid CCA Straightens out and runs parallel to skin Lies approximately 1-2 cm deep Atherosclerosis rarely involves this segment Distal CCA Continuation of vessel to the bifurcation Dilates into carotid bulb Disease frequently occurs here

30 Vessel Identification : ECA vs ICA Anatomic location ICA : lateral and posterior ECA : medial and anterior Size of Vessel ICA usually larger diameter at the origin

31 Vessel Identification : ECA vs ICA Location of the bulb and associated flow pattern Bulb most commonly involves distal CCA and proximal ICA Flow reversal due to boundary layer separation usually extends into ICA Not useful if bulb includes only distal CCA or both ICA and ECA

32 Vessel Identification : ECA vs ICA Presence of branches ECA has eight branches ICA has no branches in ICA has no branches in the neck

33 Vessel Identification : ECA vs ICA Hemodynamic flow patterns ICA : supplies low resistance bed EDV above zero Lower systolic velocity Rounded systolic peak ECA: supplies high resistance bed EDV at or near zero Higher systolic velocity Flow reversal in late systole Direct comparison of waveforms is essential

34 Vessel Identification : ECA vs ICA Color Doppler Hemodynamic differences created by differing vascular resistance can be seen in color Doppler ICA : continuous color throughout cardiac cycle ECA : color decrease significantly in diastole Superficial temporal tap Superficial temporal artery is a branch off ECA than can be palpated in front of the ear Gentle compressions result in oscillations in spectral waveforms of ECA Spectral waveforms of ICA not affected

35 B-mode Imaging :Normal Vessel Wall Double line First line represents interface blood and intimal surface Second line represents interface between intima-media complex and the adventitia As intima thickens, lines become more widely separated As plaque develops, lines become indistinguishable due to deposition of echogenic material

36 EXAMINATION PROTOCOL anteriore laterale Asse corto Postero-laterale posteriore

37 Overview Epidemiology Clinical trials Anatomy Hemodynamic flow patterns Assessment of stenosis Classification of disease Video case presentation Dipartimento Cardio-Toracico - Università di Pisa

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39 Atherosclerosis of the Carotid Bulb Disease of branch points and bifurcations Some arterial segments spared Distal to subclavian origin Internal mammary arteries Carotid bifurcation Carotid bulb is only prominent dilatation in an arterial segment Disease starts in the posterolateral aspect of bulb Progresses circumferentially to involve entire bulb Rarely extends beyond the distal margin of the bulb

40 STUDIO ECOGRAFICO DELLA MALATTIA CAROTIDEA STUDIO DELLA PLACCA SEDE ED ESTENSIONE (asse longitudinale e trasversale) A. MODULO ECOCOLOR MORFOLOGIA CARATTERIZZAZIONE PLACCA BASSA-MEDIA ALTA ECOGENICITA OMOGENEA/ETEROGENEA SUPERFICIE (REGOLARE, IRREGOLARE, ULCERATA MODULO DOPPLER SEVERITA STENOSI ( GRADING ) Dip. di Cardio-Toracico - Università di Pisa

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45 PLACCA CAROTIDEA MORFOLOGIA ECOGENICITA ASPETTO TIPO SUPERFICIE

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52 PLACCA CAROTIDEA

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72 VALUTAZIONE CORRETTA DEL GRADO DI STENOSI CAROTIDEA Asse lungo Asse corto Percentuale di stenosi lineare Analisi del Segnale Doppler % stenosi planimetrica

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74 Assessment of Severity Minimal to moderate disease (<50%) B-mode imaging is highly sensitive and reliable for identifying stenoses of less than 50% Plaques, wall, and lumens usually clearly defined Severe disease (>50%) Doppler spectral waveform most accurate method for defining severity of disease Typical complex plaques seen in high grade lesions are usually not well visualized

75 Nature of flow patterns distal to stenosis

76 VALUTAZIONE DOPPLER DELLA STENOSI CAROTIDEA 90% Dip. di Cardio-Toracico - Università di Pisa

77 Over the years, many hybrid and different stenosis measurement algorithms arose!!! Each with their own set cut points of validity, most appropriately based on ROC curve analysis. The problem was, there were just so many different velocity criteria being used that there was substantial difficulty getting comparisons and standardization in readings between facilities.

78 Cardiac and Thoracic Department - University of Pisa

79 DOPPLER EVALUATION OF CAROTID STENOSIS developed recommendations for diagnosis and stratification of ICA stenosis derived from analysis of numerous studies. Cardiac and Thoracic Department - University of Pisa

80 DOPPLER EVALUATION OF CAROTID STENOSIS internal validation is encouraged when possible. Important points from the Consensus Panel each laboratory should have a single set of diagnostic criteria that is applied uniformly.

81 DOPPLER EVALUATION OF CAROTID STENOSIS: The consensus recommended that the NASCET method of carotid stenosis measurement should be employed...when angiography is used to correlate the US findings.

82 Additional Doppler parameters other than ICA PSV The ICA/CCA ratio becomes important to use in situations where the ICA PSV may not be by itself, representative of the extent of ICA disease due to: Tandem ICA stenosis Elevated CCA velocities or stenosis Contralateral high-grade ICA stenosis Discrepancy between visual assessment of plaque and ICAPSV Significantly altered Cardiac output states (high or low) Cardiac and Thoracic Department - University of Pisa

83 Additional Doppler parameters other than ICA PSV End diastolic velocity Really starts to increase at higher levels of stenosis, usually at or above 75% diameter luminal narrowing. Cardiac and Thoracic Department - University of Pisa

84 Accuracy predicated upon Proper angle of insonation = always less than or equal to 60 degrees. Proper placement of the Doppler cursor in the center of the flow stream with the cursor in the direction of flow. Cardiac and Thoracic Department - University of Pisa

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98 Normal carotid bifurcation Cardiac and Thoracic Department - University of Pisa

99 Criteria for Less Than 50% Diameter Reduction Normal Peak systolic velocity less than 125 cm/s No visible plaque on B-mode Boundary layer separation in carotid bulb 1% to 15% diameter reduction Peak systolic velocity less than 125 cm/s No boundary separation in carotid bulb Minimal spectral broadening 16% to 49% diameter reduction Peak systolic velocity less than 125 cm/s Marked spectral broadening with no systolic window

100 50-69 % Stenosis ө=48 Cardiac and Thoracic Department - University of Pisa

101 Velocities of > 70 % stenosis (subset > 80 % ) Cardiac and Thoracic Department - University of Pisa

102 Detection of Carotid Artery Stenosis by in vivo Duplex Ultrasound Correlation with Planimetric Measurements of the Corresponding Post-mortem Specimens Stroke 2002 Steno-occlusive occlusive range from 8.5% to 100% Cardiac and Thoracic Department - University of Pisa

103 Cardiac and Thoracic Department - University of Pisa

104 Why do we report stenosis in a Range? Significant overlap of velocities at the same level of stenosis exists this is the reason that stenoses are reported in ranges and not specific %. The higher the velocity, the tighter the stenosis up to about 97 %, then the velocities start to decrease (string sign) trickle of flow. Cardiac and Thoracic Department - University of Pisa

105 ABILITY TO USE DUPLEX US TO QUANTIFY ICA STENOSES: FACT OR FINCTION? Radiology 2000 PSV AND ICA/CCA ratio INCREASED WITH STENOSIS LEVEL p<.01 that the average Doppler velocity rises in direct proportion to the degree of stenosis as determined with angiography. there are very wide ranges of Doppler values around those means, which makes it impossible to classify lesions into gradations as narrow as 10%.

106 ABILITY TO USE DUPLEX US TO QUANTIFY ICA STENOSES: FACT OR FINCTION? Radiology 2000 US is most accurate when lesions are classified as being above or below a single level, such as 60% stenosis or 70% stenosis

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126 CORSO DI CERTIFICAZIONE DI COMPETENZA in ECOGRAFIA VASCOLARE GENERALE Lezione 3 Tronchi Sovraortici Settore formazione : Direttore: Paolo G. Pino Marco Campana, Antonella Moreo, Fausto Rigo, Ketty Savino