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Extracranial Cerebrovascular Evaluation

Extracranial Cerebrovascular Evaluation. Carotid Duplex. Carotid - Objectives. Risk factors for Cerebrovascular Disease Stroke Patient Presentations Doppler profiles of the Carotid and Vertebral Arteries Hemodynamics of Flow Carotid Duplex Examination Protocol. Risks Factors. Age Sex

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Extracranial Cerebrovascular Evaluation

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  1. Extracranial Cerebrovascular Evaluation Carotid Duplex

  2. Carotid - Objectives • Risk factors for Cerebrovascular Disease • Stroke • Patient Presentations • Doppler profiles of the Carotid and Vertebral Arteries • Hemodynamics of Flow • Carotid Duplex Examination Protocol

  3. Risks Factors • Age • Sex • Hypertension • Diabetes

  4. Risk Factors • Cholesterol • Smoking • Obesity • Sedentary lifestyle • Atrial fibrillation and other cardiac diseases

  5. CVA- Stroke Neurologic deficit that correspond to an insult in a region supplied by a major cerebral artery.

  6. CVA- Stroke • Ischemic 80% • Hemorraghic 20%

  7. CVA- Stroke • CVA (Cerebrovascular Accident) –symptoms are permanent. • RIND (Reversible Ischemic Neurologic Deficit) -symptoms last >24 hrs. • TIA (Transient ischemic attack) – symptoms last <24 hrs.

  8. Mechanism of Stroke • Large vessel athero-thrombotic (30%) • Diameter reduction by plaque or thrombus. • Embolization from a thombogenic plaque surface. • Cardio – embolic stroke (35%) • Atrial fibrillation – atrial thrombus • Poor systolic function – LV thrombus

  9. Mechanism of Stroke • Lacunar Stroke (10%) • Occlusion in the small perforating vessels of the brain • Other • Dissection • Coagulopathy • Paradoxical emboli • Undetermined

  10. Symptomatic Amorisis fugax, Unilateral Weakness (Paresis), Numbness, Aphasia, dysphasia, Hemianopsia Loss of Consciouness, Cortical blindness, Dizziness, Ataxia, Dysarthria Dizziness, syncope, headache confusion Patient Presentation Anterior Posterior Non- localizing

  11. Patient Presentations • Bilateral symptoms = Vertebro-basilar • Extremity = Opposite brain • Eyes = Same side

  12. Asymptomatic Bruit Family history Cardiac patient Follow up stent or endarterectomy Patient Presentation

  13. Subclavian Artery Waveform • Triphasic or Biphasic signal

  14. Normal Waveforms: Low resistance pattern Common Carotid Artery- CCA Velocity Range: • 60-100 cm/sec • CCA-Combined ICA/ECA

  15. Carotid – CCA

  16. CCA - Bulb

  17. Normal Waveforms: Low resistance Internal Carotid Artery - ICA Velocity Range: • 60-100 cm/sec • Size: • Larger than ECA

  18. ICA

  19. ICA & ECA

  20. Normal Waveforms: High resistance Temporal tap External Carotid Artery - ECA Velocity Range: • 60-100 cm/sec Branch

  21. External Carotid Artery - ECA • Smaller than ICA • Branches

  22. Carotid - Vertebral • Waveform: • Low resistance • Anterior direction • Location: • Posterior & lateral to the CCA • Identified between vertebral • bodies

  23. Vertebral

  24. Vertebral

  25. Exam Components Grayscale

  26. Exam Components Gray Scale – Plaque Evaluation • Location • Length • Composition • Surface

  27. Exam Components High Risk Plaque • Hypoechoic plaque • Type 1 and 2 echolucent plaque • Heterogeneous plaque

  28. Exam Components • High Risk Plaque • Hypoechoic • Types 1 and 2 echolucent plaques • Heterogenous plaques

  29. Exam Components Color

  30. Exam Components Color • Flow void • Aliasing • Turbulence

  31. Exam Components Spectral

  32. Exam Components Spectral Doppler • Direction of flow • Velocity of flow • Pulsatility • Spectral Broadening

  33. Exam Components

  34. Flow Dynamics

  35. Flow Dynamics • Laminar Flow • Plug Flow • Flow Separation

  36. Laminar Flow • The velocity in the center is fastest. • The mean velocity across the vessel is ½ • the max velocity.

  37. Laminar Flow

  38. Poiseuille’s Law • Relationship between pressure, volume flow and resistance • As radius decreases velocity increase Q= (P1 – P2)π r4 8η L V = Q/A

  39. Reynolds Number • Pressure/Flow relationship • Velocity and size of vessels main variables • When Reynolds number > 2000, laminar flow becomes disturbed (turbulent flow) Re = Vq2r η

  40. Bernoulli • Velocity and Pressure are inversely related • Flow separations • High velocity Large pressure gradient • Low velocity Small pressure gradient • Flow separations may be caused by changes in the geometry of the vessel or the direction of the vessel

  41. History Blood Pressure Greyscale TRV CCA (prox, mid, dist) BULB BIFURCATION ICA ECA Sagital CCA (prox, dist) BULB ICA Carotid – Protocol

  42. Color Doppler CCA (prox, mid, dist) BULB ICA (prox, dist) Vertebral Carotid – Protocol

  43. Pulsed Wave or spectral display Subclavian CCA (prox, mid, dist) ICA (prox, mid, dist) ECA (Temporal ta) Vertebral Carotid – Protocol

  44. Measurement/Parameters • Peak Systolic Velocity (PSV) • Best documented parameterLimitation: Cardiac Output/Blood pressure • End Diastolic Velocity (EDV) • Highly accurate for greater than 80% stenosis • Systolic Velocity Ratio (ICPSV/CCPSV) • Compensates for patient Hemodynamic Variables

  45. Stenosis Evalution Doppler Evaluation of Stenosis • Before the Stenosis • Increased in pulsatility • At the Stenosis • High Velocity jet • After the stenosis • Post stenotic flow disturbances • Decreased pulsatility

  46. Stenosis Evalution B- Mode • Diameter Reduction • Area Reduction

  47. Stenosis Evalution Free lumen Plaque

  48. Stenosis Evalution a b Diameter Reduction = (a-b)/a x 100

  49. Stenosis Evalution Area a Area Reduction = (Area a- Area b)/Area a x 100 Area b

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