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TRANSCRANIAL DOPPLER ULTRASOUND

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TRANSCRANIAL DOPPLER ULTRASOUND INTRODUCTION TO TCD Nicolet Vascular, Inc. A Division of VIASYS HEALTHCARE WHAT IS TCD? TCD (Transcranial Doppler) is a non-invasive ... – PowerPoint PPT presentation

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Title: TRANSCRANIAL DOPPLER ULTRASOUND


1
TRANSCRANIAL DOPPLER ULTRASOUND
  • INTRODUCTION TO TCD
  • Nicolet Vascular, Inc.
  • A Division of
  • VIASYS HEALTHCARE

2
WHAT IS TCD?
  • TCD (Transcranial Doppler) is a
  • non-invasive assessment of cerebral blood
    flow in the basal cerebral arteries
  • Utilizes low frequency Doppler ultrasound

3
WHAT IS TCD?
  • Uses 2 MHz pulsed Doppler ultrasound
  • Passes through cranial windows
  • Provides information regarding velocity and
    direction of cerebral blood flow

4
Middle Cerebral Artery
5
(No Transcript)
6
BLOOD FLOW VELOCITY
  • Changes in flow velocity occur when
  • There is a change in vessel caliber
  • There is a change in volume flow

7
TRANSCRANIAL DOPPLER
  • Non-invasive
  • Painless
  • Inexpensive
  • Can provide instantaneous and continuous
    cerebral blood flow information
  • Can be used in any hospital environment
  • Safe

8
DEVELOPMENT OF TCD
  • 1982 Dr. Rune Aaslid
  • First publication Transtemporal Approach
  • 1984 Dr. Merrill Spencer
  • First publication Transorbital Approach
  • 1986 Dr. M. Von Reutern
  • First publication Suboccipital Approach
  • 1983 First commercial TCD unit (EME)

9
TCD APPLICATIONS
  • Accepted applications (AAN)
  • Detect intracranial stenosis
  • Follow the time course of vasospasm
  • Confirm the diagnosis of brain death
  • Assist in the detection an management of AVMs

American Academy of Neurology
10
TCD APPLICATIONS
  • Other reported uses
  • Assess of collateral pathways
  • Assess autoregulation and vasomotor reactivity
  • ICU monitoring (effects of ICP)
  • Surgical monitoring (CEA, CABG)
  • Detection of emboli (HITS)
  • Aid in classification of strokes

11
TCD APPLICATIONS
  • Other reported uses
  • Subclavian steal assessment
  • Assess mechanical compression of the vertebral
    arteries
  • Evaluate Sickle Cell patients
  • Evaluate patients with carotid dissections

12
TCD APPLICATIONS
  • Assess the effects of pharmacological
    interventions
  • Research applications
  • Surgical monitoring

13
INTRAOPERATIVE MONITORING APPLICATIONS
  • Carotid Endarterectomy
  • Carotid Stenting
  • Coronary Artery Bypass Surgery
  • Cardiac Valve Surgery
  • Abdominal Aortic Aneurysm
  • Liver Transplants
  • Orthopedic Surgery

14
TCD MONITORING
  • Patent Foramen Ovale evaluation
  • Implantable cardioverter defibrillator testing
  • Any procedure where knowledge of the state of
    blood flow to the brain is of critical importance

15
TRANSCRANIAL DOPPLER
  • EXAMINATION TECHNIQUE

16
TCD - APPROACHES
  • Transtemporal
  • Transorbital
  • Suboccipital (Transforaminal)
  • Submandibular

17
TRANSCRANIAL DOPPLER ACCESS ROUTES
18
TRANSTEMPORAL APPROACH
  • Middle Cerebral Artery MCA
  • Anterior Cerebral Artery ACA
  • Terminal Internal Carotid Artery T-ICA
  • Posterior Cerebral Artery PCA
  • Communicating Arteries
  • Anterior Communicating Artery ACoA
  • Posterior Communicating Artery PCoA

19
CRITERIA FOR VESSEL IDENTIFICATION
  • Depth of the sample volume
  • Direction of flow
  • Traceability of the vessel
  • Transducer angulation
  • Spatial relationship of spectra
  • Response to carotid or vertebral oscillations or
    compressions

20
TRANSTEMPORAL WINDOWS
FW
AW
Frontal
MW

PW
PW
MW
AW
21
Middle Cerebral Artery
22
MCA / ACA
23
Anterior Cerebral Artery
24
Posterior Cerebral Artery P1
25
TRANSORBITAL APPROACH
  • Ophthalmic Artery OA
  • Internal Carotid Artery Siphon
  • Parasellar
  • Genu
  • Supraclinoid

26
Ophthalmic Artery
27
Carotid Siphon - Genu
28
SUBOCCIPITAL APPROACH
  • Vertebral Artery VA
  • Basilar Artery BA

29
Vertebral Artery
30
Basilar Artery
31
NORMAL VELOCITY RELATIONSHIPS
  • MCA gt ACA gt PCA
  • PCA VA and BA

32
PRIMARY DIAGNOSTIC FEATURES
  • Changes in velocity
  • Changes in pulsatility
  • Changes in systolic upstroke
  • Changes in flow direction
  • Side to side differences
  • Embolic phenomena (HITS)

33
TRANSCRANIAL DOPPLER
  • COLLATERAL CIRCULATION

34
Effects of Extracranial Carotid Stenosis /
Occlusion
  • Factors affecting cerebral blood flow
  • Degree of proximal stenosis
  • Size and extent of collateral channels

35
EFFECTS OF CAROTID STENOSIS
  • Mild to Moderate Stenosis (lt /- 75)
  • TCD exam Essentially normal
  • Severe Stenosis (gt /- 75)
  • TCD exam Abnormal
  • Changes in Doppler spectral waveform shape
  • Changes in flow patterns (Collateral)

36
WAVEFORM CHANGES
  • Decreased velocity
  • Delayed systolic upstroke
  • Decreased pulsatility

37
DOPPLER WAVEFORM CHANGES
Normal MCA
Abnormal MCA
38
COLLATERAL SOURCES
  • Collateral detectable by TCD include
  • Circle of Willis, including the vertebrobasilar
    system
  • ECA to ICA collateral via the ophthalmic artery

39
COLLATERAL SOURCES
  • Collateral not detectable by TCD include
  • Branches of the ECA connecting to branches of the
    vertebral artery
  • Leptomeningeal anastomoses

40
INTRACRANIAL STENOSIS
  • Focal elevated velocities above adjacent segments
  • Side to side differences exceeding normal
    variation (usually gt 15 or 30 cm/sec
    between right and left MCA)
  • Downstream effects
  • Turbulence
  • Delayed systolic upstroke
  • Decreased velocity

41
TCD WAVEFORMS WITH INTRACRANIAL STENOSIS
42
INTRACRANIAL STENOSISCauses
  • Atherosclerosis
  • Intraluminal thromboembolism
  • Arterial dissection
  • Moyamoya disease
  • Vasculitis
  • Vasospasm
  • Extrinsic vessel compression

43
TRANSCRANIAL DOPPLER
  • EMBOLI DETECTION
  • (HITS)

44
EMBOLIC EVENTS
  • Foreign solids and / or gaseous materials within
    the blood stream
  • Reflect sound waves more intensely than
    surrounding red blood cells
  • Characterized by an audible chirp and
    simultaneous visual HIT on the screen

45
TCD - EMBOLI DETECTION
  • Can detect the presence of embolic signals caused
    by the presence of a variety of materials, both
    gaseous and solid
  • Cannot determine the size of an embolus
  • Cannot determine the composition of an embolus
  • Can detect particles as small as 50 microns

46
EMBOLI RECOGNITION International Consensus
Committee
  • Short lt 0.1 second, 3-60 dB transients
  • Unidirectional in spectra
  • Occur randomly in cardiac cycles
  • Change frequency within spectrum
  • Audible sound chirps, clicks, plunks
  • Solid vs. air emboli distinguished by
    circumstance (solid designated when there is no
    invasion of vasculature)

47
EMBOLI DETECTION
  • Carotid artery stenosis
  • Arterial dissection
  • Post endarterectomy
  • Heart valve replacement
  • Patent foramen ovale
  • Atrial fibrillation
  • Significant CHF
  • Endocarditis
  • Acute MI

48
MCA Microembolic Signal (MES)
49
Transcranial Doppler
  • Paradoxical Stroke
  • and
  • PFO Evaluation

50
Ischemic Stroke
  • Represents the third greatest cause of death in
    the western word
  • Is the greatest cause of functional incapacity
  • Origin is undetermined in 40 of cases according
    to conventional etiological criteria

Sacco R.L.,et al, Infarcts of undetermined cause
the NINCDS Stroke Data Bank. Ann. Neurol.
198925382-390
51
Cryptogenic Stroke
  • Stroke of unknown etiology
  • Suspicion of paradoxical brain emboli arising
    from the venous circulation
  • Emboli from the venous system can pass to the
    arterial circulation through
  • a PFO (Patent foramen ovale)

52
Paradoxical Brain Emboli (PBE)
  • Emboli whose source is not from an identifiable
    source in the arterial system
  • Also referred to as venous-to-arterial emboli

53
Positive TCD Bubble Test Shower Type HITS with
Valsalva Maneuver
R MCA
L MCA
54
TRANSCRANIAL DOPPLER
  • Cerebral Circulatory Arrest

55
TCD - BRAIN DEATH
  • Brain death is a clinical diagnosis
  • TCD is a confirmatory test
  • TCD can detect cerebral circulatory arrest

56
Transcranial Doppler
  • Can aid in timing of other necessary tests
  • Helpful in following potential organ donors
  • Useful when patients are being treated with
    barbiturates which affect EEG

57
CEREBRAL CIRCULATORY ARRESTTCD Evaluation
  • Bilateral study including posterior circulation
  • Oscillating flow pattern persists over time (20
    30 minutes minimum)

58
CEREBRAL CIRCULATORY ARREST
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