Pitfalls in the evaluation of carotid artery stenosis. Serge Kownator «Centre Cardiologique et Vasculaire» Thionville, Fr

Transcription

1 Pitfalls in the evaluation of carotid artery stenosis Serge Kownator «Centre Cardiologique et Vasculaire» Thionville, Fr

2 Disclosure Statement of Financial Interest I currently have, or have had over the last four years, an affiliation or financial interests or interests of any order with a company or I receive compensation or fees or research grants with a commercial company : Affiliation/Financial Relationship Grant/Research Support Consulting Fees/Honoraria Company Astra Zeneca, Bayer Amgen, Bayer, Boehringer Ingelheim, Daiichi Sankyo, MSD, Sanofi, Philips. Major Stock Shareholder/Equity Royalty Income Ownership/Founder Intellectual Property Rights Other Financial Benefit none none none none none

3 Which pitfall Ignore, under or overestimate Pitfall related to physical examination Pitfall related to language Pitfall related to imaging

4 Physical examination Carotid bruit? Northern Manhattan Study (NOMAS): 686 subjects with a mean age of 68.2 ± 9.4 years Prevalence of carotid bruit: 4.1 % DUS => 2.2% carotid stenosis 60% Sensitivity of auscultation : 56% Specificity 98%, PPV: 25% - NPV: 99% Accuracy was 97.5%. 44% false-negative rate suggests that auscultation is not sufficient to exclude carotid stenosis. Ratchford EV et al. Neurol Res September ; 31(7):

5 Language! Prevalence of serious carotid stenosis > 50% = 4.2% (CI, 3.1%-5.7%) > 70% = 1.7% (CI, 0.7%-3.9%) Adults over 70 years: 6.9 % in women 12.5 % in men (incl. occlusion) Moderate Severe de Weerd M et al. Stroke. 2009;40: Stroke Jun;41(6):

6 Language! What Means Carotid Stenosis? Method of grading B 6

7 Language! Method of grading Area reduction vs diameter reduction (NASCET or ESCT)

8 Imaging DUS - commonly used as the first step to detect extracranial carotid artery stenosis and to assess its severity CTA - widely available and allows for a differenciation between ischaemic and haemorrhagic stroke MRA - more sensitive in the detection of brain ischaemia European Heart Journal (2011) 32,

9 DUS: Evaluation of the degree of stenosis DUS evaluation of the degree of stenosis relies mostly on Doppler velocities Velocities translates in diameter reduction! 373 cm/s

10 DUS: Evaluation of the degree of stenosis Bernouilli s Equation PSV Spencer MP et al. Stroke ;3: % of stenosis 10

11 Doppler s Ambiguity Bernouilli s Equation PSV Spencer MP et al. Stroke ;3: Polak J et al. RADIOLOGIC CLINICS OF NORTH AMERICA, may % of stenosis 11

12 Doppler s Ambiguity

13

14 DUS s Pitfalls Technical issues (Relates to the physician) Calcifications Kinkings and loops Controlateral occlusion Occlusion or pseudo-occlusion? Increased output ( hyperthyroidy, arterio-veinous fistula) Decreased output : proximal or distal disease Relates to the patient

15 Technical issues Settings Probe Position of the sample volume Angle-related issue 40 cm/s 350 cm/s 70 cm/s

16 Calcifications Tip : Adjustment of the settings Lower PRF Higher overall gain Low frequency probe Contrast Enhanced US ++ A major limit for DUS Patient A Patient B

17 Calcifications (2) Patient A Patient B

18 Calcifications (3) Patient A Patient B 220 cm/s Tip Look for an aliasing in color Doppler Place the cursor just downstream the calcification

19 Tortuosity, Loops and Kinkings The velocities of tortuous vessels are complex to understand: Aliasing Pseudo stenosis. Tip: Careful angle alignment Wide angle probe

20 Controlateral disease Ipsilateral occlusion of the ICA (or high grade stenosis) may cause an increase in the flow of controlateral carotid (if collateralization depends on the ACA) The carotid ratio will remain in the normal range if there is no stenosis even with increased velocities. Systolic Carotid Ratio: PSV ICA/ PSV CCA R ICA occlusion LICA : PSV L ICA 373 cm/s EDV L ICA 148 cm/s CR 3.2

21 Occlusion or pseudo-occlusion Sometimes difficult Requires CEUS Few clinical relevance String sign

22 Increased output Think hyperthyroidy if global multivessel increased velocities Think arterio venous fistula if unilateral increased velocities (more often ECA) Tip: Check carefully both sides

23 Decreased output Overall cardiac output All the velocities will be affected = > carotid ratio +++ Aortic stenosis Bilateral decrease of the velocities and increased ascending time Proximal CCA or BCT Asymetric flow change Aortic stenosis Increased ascending time

24 Distal disease Decrease of the overall velocities ispsilateraly Decrease of the diastolic velocities

25 Power S et al. European Journal of Radiology. 84; July 2015: Pitfalls in CTA «False occlusion» sign Differentiation between occlusive and partially occlusive thrombus Heavy calcification CTA do not provide information on flow (4D CTA?)

26 Pitfalls in MRA Villablanca P Brain Mapping for Translational Investigators January 12, 2012

27 Conclusion As far as therapeutic strategy relies mostly on the degree of stenosis for symptomatic and for asymptomatic patients the technical aspects are of major importance The «Language misunderstanding» is probably the first pitfall to avoid All the imaging techniques are operator depending => skill, skill and skill!

28 DUS and Carotid stenosis New consensus 2012 Neurosonology Research Group of the World Federation of Neurology Von Reutern G et al. Stroke. 2012;43: