This free webinar hosted by Scintica Instrumentation provides an overview of performing “Doppler” measurements for preclinical cardiovascular assessment. It will discuss the physical principles and technology used to acquire these measurements, how these techniques are employed in the preclinical field, and a short summary of the history behind the technology that so many researchers use every day. The focus of the webinar will be on the considerations that must be made when using these techniques, as well as the relevant methods and publications that help to describe how these techniques are being used in research.

1. Nicky Pansters, Ph.D.
Scintica Instrumentation
Phone: +31 6 3811 2536
npansters@scintica.com
Doppler Flow Velocity:
Cardiovascular Research
Applications

2. • A little bit of history on the technique and technology
• Some basics of Doppler Flow Velocity
• Use of the “Doppler” principle for different preclinical systems, ultrasound vs. laser
• The data that can be obtained from “Doppler” measurements
• Considerations when using the ultrasound-based systems
• Highlights of published applications using blood flow velocity
TOPICS OF DISCUSSION

3. Messer 2005 (MSc thesis)
HERTZ
Human
SOUND

4. THE DOPPLER EFFECT (OR DOPPLER SHIFT)
• Definition:
The change in frequency or wavelength of a
wave in relation to an observer who is moving
relative to the wave source.
• Austrian Christian Andreas Doppler in 1842
• Dutch student Christoph H.D. Buys Ballot
contested his idea in 1845

5. Where
c = speed of the wave in the medium
Vr = speed of the receiver relative to the
medium
Vs = speed of the source relative to the
medium
f = frequency at the point of observation
f0 = frequency at the point of origin
𝑓 =
𝑐 ± 𝒗 𝑟
𝑐 ± 𝑣𝒔
𝑓0
𝑣 =
𝑐 × Δ𝑓
2 × 𝑓0 × cos 𝜃
Where
V = flow velocity (cm/sec)
c = velocity of sound (cm/sec)
Δf = Doppler shift (Hz)
fo = transmission frequency (Hz)
θ = angle between velocity vector & beam vector
DOPPLER EQUATION FOR FLOW VELOCITY

6. 1920’s 1930-1950’s 1960’s 1970’s 1980’s Present
Edler and Hertz at Lund University
Early M-MODE
Harvey Feigenbaum
Standardize for medical practice
Satomura US Doppler in Osaka
2D Ultrasound – B MODE
2D Ultrasound – Color Doppler
Ultrasound – computer post analyzing images
Assessing flaws in metal
ULTRASOUND IN THE MEDICAL FIELD – HIGHLIGHTS

7. • Ultrasound is a non-invasive
• "Doppler" has become synonymous with "velocity measurement"
ULTRASOUND IMAGING & FLOW VELOCITY

8. ULTRASOUND IMAGING & FLOW VELOCITY – PRECLINICAL
• High-frequency ultrasound waves are necessary to resolve the small anatomical targets
in preclinical research

9. θ = angle between velocity vector & beam vector
DOPPLER EQUATION FOR FLOW VELOCITY
Where
c = speed of the wave in the medium
Vr = speed of the receiver relative to the
medium
Vs = speed of the source relative to the
medium
f = frequency at the point of observation
f0 = frequency at the point of origin
𝑓 =
𝑐 ± 𝒗 𝑟
𝑐 ± 𝑣𝒔
𝑓0
𝑣 =
𝑐 × Δ𝑓
2 × 𝑓0 × cos 𝜃
Where
V = flow velocity (cm/sec)
c = velocity of sound (cm/sec)
Δf = Doppler shift (Hz)
fo = transmission frequency (Hz)
θ = angle between velocity vector & beam vector

10. 90°
right carotid
ECHOCARDIOGRAPHY & DOPPLER FLOW VELOCITY - ANGLES
• High-frequency ultrasound imaging of the carotid artery & flow velocity assessment

11. Where
V = flow velocity (cm/sec)
c = velocity of sound (cm/sec)
Δf = Doppler shift (Hz)
fo = transmission frequency (Hz)
θ = angle between velocity
vector & beam vector
Angle = ~15°
𝑣 =
𝑐 × Δ𝑓
2 × 𝑓0 × cos 𝜃
ANGLE EFFECT ON BLOOD FLOW VELOCITY CALCULATION

12. Ultrasound image
Doppler flow velocity
ANGLE EFFECT ON BLOOD FLOW VELOCITY CALCULATION
Where
V = flow velocity (cm/sec)
c = velocity of sound (cm/sec)
Δf = Doppler shift (Hz)
fo = transmission frequency (Hz)
θ = angle between velocity
vector & beam vector
𝑣 =
𝑐 × Δ𝑓
2 × 𝑓0 × cos 𝜃

13. Where
V = flow velocity (cm/sec) = Calculated
c = velocity of sound (cm/sec) = 1540m/sec
Δf = Doppler shift (Hz) = 20kHz
fo = transmission frequency (Hz) = 20Mhz
θ = angle between velocity = Variable input
vector & beam vector
@ angle of 0 degrees velocity in 0.75 m/s
@ angle of ~90 degrees velocity in ∞ m/s
𝑣 =
𝑐 × Δ𝑓
2 × 𝑓0 × cos 𝜃
Applying angle correction on velocity calculation!
ANGLE EFFECT ON BLOOD FLOW VELOCITY CALCULATION

14. Where
V = flow velocity (cm/sec) = Calculated
c = velocity of sound (cm/sec) = 1540m/sec
Δf = Doppler shift (Hz) = 20kHz
fo = transmission frequency (Hz) = 20Mhz
θ = angle between velocity = Variable input
vector & beam vector
0 15 30 45 60 75 90
0
5
10
15
20
25
30
35
40
45
measurement angle (degrees)
FlowVelocitym/s
@ angle of 0 degrees velocity in 0.75 m/s
𝑣 =
𝑐 × Δ𝑓
2 × 𝑓0 × cos 𝜃
ANGLE EFFECT ON BLOOD FLOW VELOCITY CALCULATION

15. Size of probe affects minimal angle of approach for performing Doppler flow velocity measurement
Sawada et al. 2019
0 15 30 45 60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
measurement angle (degrees)
FlowVelocitym/s
@ angle of 0 degrees velocity in 0.75 m/s
ANGLE EFFECT ON BLOOD FLOW VELOCITY CALCULATION

16. Greater Accuracy with Smaller Angle of Measurement
0 5 10 15 20
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
measurement angle (degrees)
FlowVelocitym/s
40 45 50 55 60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
measurement angle (degrees)
FlowVelocitym/s
@ angle of 0 degrees velocity in 0.75 m/s
ANGLE EFFECT ON BLOOD FLOW VELOCITY CALCULATION

17. Where
V = flow velocity (cm/sec)
c = velocity of sound (cm/sec)
Δf = Doppler shift (Hz)
fo = transmission frequency (Hz)
θ = angle between velocity
vector & beam vector
Achieve consistency and accuracy for your research data
with proper angle correction
Angle = ~15°
𝑣 =
𝑐 × Δ𝑓
2 × 𝑓0 × cos 𝜃
PULSED DOPPLER ULTRASOUND FLOW VELOCITY

18. • A little bit of history on the technique and technology
• Some basics of Doppler Flow Velocity
• Use of the “Doppler” principle for different pre-clinical systems, ultrasound vs. laser
• The data that can be obtained from “Doppler” measurements
• Considerations when using the ultrasound-based systems
• Highlights of published applications using blood flow velocity
TOPICS OF DISCUSSION

19. • Method of assessment
• Transition time
• Assesses
• Flow : volume / time
• Considerations
• Assume condition of blood and thickness
and composition of artery
• (minimal) invasive
• Method of assessment
• Pulsed Doppler
• Assesses
• Velocity: distance / time
• Considerations
• Assume condition of blood and body
composition
• Knowledge of anatomy and flow velocity
spectrographs
ULTRASONIC FLOW VELOCITY

20. Contact measurement
Heuslein et al. 2016
Overview measurement
LASER DOPPLER FLOW VELOCITY
• Consideration
• Penetration depth~1mm
• Arbitrary units or color scheme
Rajan et al. 2009

21. • More sensitive than Color
Doppler
• Does not provide information
about the direction of blood flow
Image from http://www.annalsofian.org
• Converts the blood flow velocity
measurements into an array of
colors
OTHER “DOPPLER” FROM ULTRASOUND ECHO SYSTEM

22. COME FIND YOUR DOPPLER APPLICATION NEEDS
Laser
Flow
velocity
Imaging
Ultrasound

23. • A little bit of history on the technique and technology
• Some basics of Doppler Flow Velocity
• Use of the “Doppler” principle for different pre-clinical systems, ultrasound vs. laser
• The data that can be obtained from “Doppler” measurements
• Considerations when using the ultrasound-based systems
• Highlights of published applications using blood flow velocity
TOPICS OF DISCUSSION

24. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

25. The magnitude and shapes
of the inflow and outflow
left ventricle velocities in
mice are identical to
humans
Cardiac Signals and Timing
CARDIAC DOPPLER FLOW VELOCITY MEASUREMENTS

26. SCALING IN MAMMALS FROM ELEPHANTS TO MICE
General allometric equation: Y = a.BW b
Parameter Relationship to BW (kg)* Value (BW=0.025kg)
Heart weight (mg) a BW1 4.3 BW 112 mg
LV volume (μl) a BW1 2.25 BW 56 ml
Stroke volume (μl) a BW1 0.95 BW 24 ml
Heart rate (bpm) a BW-1/4 230 BW-1/4 578 bpm
Cardiac output (ml/min) a BW3/4 224 BW3/4 14 ml/min
Aortic diameter (mm) a BW3/8 3.6 BW3/8 0.9 mm
Arterial pressure (mmHg) a BW0 100 100 mmHg
Aortic velocity (cm/s) a BW0 100 100 cm/s
PW velocity (cm/s) a BW0 500 500 cm/s
*T.H. Dawson, “Engineering design of the cardiovascular system of mammals” , Prentice Hall, 1991.

27. right carotid
right renal
Velocities are similar in magnitude and shape to those from humans
left renal
aortic
arch
left carotid
descending
aorta
abdominal
aorta
| 250 ms |
ascending
aorta
100 -
50 -
0 -
coronary
Hartley et al., ILAR J 43:147-8, 2002
DOPPLER SIGNALS FROM AORTA AND ARTERIES IN MOUSE

28. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

29. MOUSE LEFT VENTRICLE DOPPLER SIGNALS
AORTIC VALVE 0UTFLOW VELOCITY WAVEFORM

30. MOUSE LEFT VENTRICLE DOPPLER SIGNALS
AORTIC VALVE 0UTFLOW VELOCITY WAVEFORM

31. MOUSE CARDIAC DOPPLER SIGNAL
AORTIC OUTFLOW WAVEFORM

32. CARDIAC SYSTOLIC PARAMETERS
AORTIC OUTFLOW WAVEFORM

33. “Invasive & Terminal”“noninvasive & repeatable”
MOUSE CARDIAC LEFT VENTRICLE CONDITION
ASSESSMENT

34. SIMULTANEOUS MEASUREMENT OF AORTIC FLOW
VELOCITY, LEFT VENTICLE PRESSURE AND ECG

35. Aortic Outflow Velocity (V)
Left Ventricular Pressure (P)
dV/dt
dP/dt
AORTIC OUTFLOW VELOCITY (V) AND ITS DERIVATIVE ( dV/dt)
LEFT VENTRICULAR PRESSURE (P) AND ITS DERIVATIVE ( dP/dt)

36. Peak aortic acceleration Mean aortic acceleration
NONINVASIVE SURROGAGE MEASUREMENT FOR PEAK + dP/dt
DERIVED FROM DOPPLER AORTIC BLOOD FLOW VELOCITY

37. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

38. Aortic valve
outflow
Mitral valve
inflow
MOUSE LEFT VENTRICLE DOPPLER SIGNALS
MITRAL INFLOW VELOCITY WAVEFORM

39. MOUSE CARDIAC DOPPLER SIGNALS
MITRAL VALVE WAVEFORM

40. • E-Time Duration
• E-Acceleration Time
• E-Deceleration Time
• E-Peak to ½ E-Peak Time
• E-Linear Deceleration Time
• A-Time Duration
• Isovolumic Contraction Time
• Isovolumic Relaxation Time
• Myocardial Performance Index (MPI)
• E-Peak Velocity
• E-Stroke Distance
• E-Linear Deceleration Rate
• A-Peak Velocity
• A-Stroke Distance
• E-A Peak Velocity Ratio
mc – mitral valve closes
ao – Aortic valve opens
ac – Aortic valve closes
mo – Mitral valve opens
CARDIAC DIASTOLIC PARAMETERS
MITRAL INFLOW WAVEFORM

41. Diastolic Function may be
measured through the mitral
valve, reported as the E/A ratio,
IVRT & IVCT, MPI, or simply the
peak E flow velocity
Systolic Function may be measured
as peak flow velocity through the
aortic valve as non-invasive
alternative to left ventricle pressure
measurement
Mitral Valve Flow
Velocity
Aortic Valve Flow
Velocity
CARDIAC FUNCTIONAL DOPPLER MEASURES

42. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

43. Normal flow
through aorta and
carotid arteries
suture
Surgical technique to
create Transverse Aortic
Constriction (TAC)
Abnormal flow through
aorta and carotid
arteries post-banding
Right carotid artery
dramatically increased flow
Left carotid artery
receives little flow
Aortic arch stenosis
flow becomes jet-like
and velocity increases
substantially
Cardiac hypertrophy model
transverse aortic constriction
O-ring model Melleby et al. Cardiovascular Research 2018

44. Right Carotid Velocity
Left Carotid Velocity
100
50
0
cm/s
100
50
0
cm/s
Pre-Band Post-Band
Aortic
constriction
Confirming surgical success
tightness of Aortic band
Peak Flow Velocity Ratio over the carotids:
𝑅𝑎𝑡𝑖𝑜 = ൗ
𝑅𝑖𝑔ℎ𝑡 𝑃𝑒𝑎𝑘 𝐹𝑙𝑜𝑤 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦
𝐿𝑒𝑓𝑡 𝑃𝑒𝑎𝑘 𝐹𝑙𝑜𝑤 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦
Simplified Bernoulli’s equation to approximate the pressure drop across the band by
measuring Aortic arch stenosis jet flow velocity post surgery :
𝜟𝑷 = 𝟒𝑽 𝟐
Where P is reported in mmHg, if V is in m/s
Hartley et al., Ultrasound Med Biol 34, 2008
1.0
2.0
0
m/s
Stenosis Jet Velocity
Pre-Band Post-Band

45. Confirming surgical success - tightness of Aortic band
stratify cohort
ΔP ≈ 49mmHg
100
50
0
cm/s
100
50
0
cm/s
200
400
0
cm/s
Tight Band
Ratio ≈ 6.2
Loose Band
ΔP ≈ 15mmHg
Ratio ≈ 4.5
Hartley et al., Ultrasound Med Biol 34, 2008
Right
Carotid
Velocity
Left
Carotid
Velocity
Stenosis
Jet
Velocity
No Band
ΔP ≈ 4mmHg
Ratio ≈ 1.0

46. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

47. • Arterial stiffness indicates atherosclerosis
related high blood pressure or hypertension
• Arterial stiffness (PWV) emerged as an
independent predictor of cardiovascular risk
Image from http://www. kidney-international.org
PULSE WAVE VELOCITY: ARTERIAL CONDITION - STIFFNESS

48. • Arterial stiffness indicates atherosclerosis
related high blood pressure or hypertension
• Arterial stiffness (PWV) emerged as an
independent predictor of cardiovascular risk
Chrinos et al. Journal of the American College of Cardiology Volume 74, Issue 9, September 2019
PULSE WAVE VELOCITY: ARTERIAL CONDITION - STIFFNESS

49. aortic
arch
• Measurement methods:
• sequential Doppler measurement
• Using R-peak at timing measure
• Attention point: requires short duration
between the sequential measurements
• Simultaneous Doppler measurement
DOPPLER SIGNALS FOR PULSE WAVE VELOCITY ASSESSMENT

50. Sequential Simultaneous
ECG signal required !
PULSE WAVE VELOCITY MEASUREMENTS

51. PWV measurement for illustration?

52. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

53. right carotid
right renal
left renal
aortic
arch
left carotid
descending
aorta
abdominal
aorta
| 250 ms |
ascending
aorta
100 -
50 -
0 -
coronary
Hartley et al., ILAR J 43:147-8, 2002
DOPPLER SIGNALS FROM AORTA AND ARTERIES IN MOUSE

54. right carotid
Doppler flow
velocity
Aorta transition
aortic
arch
descending
aorta
abdominal
aorta
ascending
aorta
• Heart rate and R‐R interval
• Maximum, Minimum and Mean velocity
• Pulsatility Index (PI) assess vascular resistance
differential across the arteriolar bed
• PI = (Vmax - Vmin) / Vmean
• Resistivity Index (RI), a.k.a. arterial resistivity index,
assess pulsatile blood flow reflecting blood
flow resistance caused by microvascular bed distal to
the site of measurement.
• RI = (Vmax - VminED) / Vmax
Hartley et al., ILAR J 43:147-8, 2002

55. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

56. • Coronary flow velocity measurement in the left main
coronary artery
• Requires use of vasodilating compound
• Assessment allows for
• Detecting conditions affecting the coronary arteries
• Determine the efficacy of treatments used
Image from http://www.doctablet.com
CORONARY FLOW RESERVE

57. Possibility to assess coronary flow reserve
Hartley et al., ILAR J 43:147-8, 2002
Points of attention
• Coronary arteries are small, ≈200μm
• They are close to many other vessels
• They move along with the heart
• To identify coronary artery ECG is required!
• Coronary blood flow occurs during the
diastolic phase
coronary
DOPPLER SIGNAL FROM LEFT MAIN CORONARY ARTERY

58. The coronary flow velocity measurement

59. • Noninvasive
• Systolic functional parameters
• Diastolic functional parameters
• Trans Aortic Constriction/Banding
• Pulse Wave Velocity
• Peripheral blood flow velocity
• Coronary Flow Reserve (ECG required)
• Invasive
• Doppler cuff probes
APPLICATION OF DOPPLER FLOW VELOCITY

60. Carter et al. 2016
UPCOMING WEBINAR: JANUARY 28, 2020
• Title: Using Doppler flowmetry approached to investigate
the haemodynamic effects of anti-cancer therapies
• Presentor: Dr. Jeanette Woolard, University of Nottingham
• Assessment of flow to distinct vascular beds
• Compounds differentially affect vascular flow beds

61. Nicky Pansters, Ph.D.
Scintica Instrumentation
Phone: +31 6 3811 2536
npansters@scintica.com
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