Doppler Basic & Hemodynamic Calculations August 19, 2017 Smonporn Boonyaratavej MD Division of Cardiology, Department of Medicine Chulalongkorn University Cardiac Center, King Chulalongkorn Memorial Hospital
3-D Echo 2
Doppler measures blood flow velocities in the heart and the great vessels, based on the Doppler effect 3
Doppler Effects 4
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Basic ECHO Doppler Shift Target stationary T f t f t = f r R f r Target moving toward transducer T R f r f t f r > f t Target moving away from transducer T R f t f r f r < f t Doppler shift or frequency (f d ) = f r -f t 6
Doppler Shift If = 0, cos = 1 1540 m/sec 7
A Comparison of Two-Dimensional Echo and Doppler 2D-Echo Doppler Ultrasound target Tissue Blood Goal of diagnosis Anatomy Physiology Type of information Structural Functional Optimal alignment between beam and target Perpendicular Parallel Preferred transducer frequency High Low 8
Why velocity? 9
Bernoulli Equation Daniel Bernoulli 8 February 1700 17 March 1782 Swiss mathematician and physicist 10
Why do we want to know the velocity? V1 V2 Simplified Bernoulli Equation Pressure gradient = 4 (V 2 2 - V 12 ) Estimation Pressure gradient = 4V 2 11
Doppler shift = 2 f t v cos θ c Adapted from ECHOSAP 12
Rule of 20 degree 13
Doppler Pulsed-wave (PW) Doppler Continuous wave (CW) Doppler Color-flow (CF) Doppler 14
Pulsed- vs Continuous-wave Doppler Pulsed-wave Continuous-wave Measures specific blood flow Measures flow along the axis Maximum measurable vel < 2 m/s Maximum measurable vel 9 m/s Performed by Duplex transducer Performed by Duplex and nonimaging transducer Low vel at specific site Peak vel across orifice Clinical applications Clinical applications LVOT velocity and TVI Peak velocity and TVI Volume measurement Valvular pressure gradient Diastolic filling parameters Pressure half-time Mitral inflow velocity Pulmonary pressure Oh JK. Echo Manual 15
Doppler Velocities Display 16
Nonimaging CW Doppler Transducer 17
Doppler Display Audio Output High pitched sounds Large Doppler shifts presence of high velocity flow Low pitched sounds lesser Doppler shifts low velocity flow Flow direction information stereophonic audio output 18
PRF Adapted from ECHOSAP 19
Sample Volume 20
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Normal Spectral Doppler LV inflow & RV inflow 22
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Normal Spectral Doppler LV outflow & RV outflow 24
Normal Spectral Doppler Pulmonary vein 25
Superior Vena Cava Flow Measurement Techniques 26
Maximum frequency determined = 1/2 of the PRF (Nyquist frequency) Adapted from ECHOSAP 27
High PRF Doppler 28
Adapted from ECHOSAP 29
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AV Continuous-wave Doppler Pressure Gradient 31
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Doppler Control Panel 33
Doppler Gain "mirroring" or "crosstalk" 34
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Greyscale 36
Wall Filter 37
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Scale & Baseline Control 39
Pulsed Sample Depth & Size Deeper positioning of the sample volume > an automatic decrease in the Nyquist limit. Most users of pulsed Doppler will leave this gate in a midposition for routine scanning decrease or increase the size of the gate depending on the clinical situation 40
Color Flow Doppler 41
Color Doppler Imaging Utilizes multigated Pulse wave Doppler to estimate mean blood flow velocity Direction of blood flow is displayed using the traditional `BART colour scheme where flow away from the probe appears blue (BA) and flow towards the probe appears red (RT). There are 2 colour maps commonly encountered on echo machines: 42
Color Flow Doppler 43
Color Flow Imaging Turbulence Red to Yellow fast Red Yellow Magenta Blue Blue Green Flow direction Forward Reverse slow slow fast Flow velocity Turbulence Blue to Cyan Omnoto & Kasai Echocardiography 1987 44
Color Doppler Velocity Map - 45
Color Doppler Variance Mode Laminar flow is blue or red; turbulent flow is yellow or green http://pie.med.utoronto.ca 46
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Color Flow Doppler Color Aliasing 0.42 0.42 49
Color Flow Doppler Mitral Regurgitation 0.35 0.35 50
Mitral regurgitation Direction of Color Flow Jet Eccentric Central 51
Colour Doppler Images Ensure colour box covers the entire area of interest, Set the Nyquist limit scale appropriate to the structure of interest. Valvular and arterial structures is 50-70 cm/sec. Slower velocity venous structures and the assessment of the interatrial septum is 30-50 cm/sec 52
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Hemodynamics assessment Mean RAP (CVP) Pulmonary artery (PA) pressure PA systolic pressure PA diastolic pressure Left atrial pressure (LAP) Left ventricular enddiastolic pressure (LVEDP) Stroke volume (SV) and cardiac output (CO) Quantitation of Valve regurgitation Shunt volume Ventricular function Systolic Diastolic 54
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Time - velocity Integral (TVI) 56
Pulmonary Artery Pressure TR peak velocity = RV systolic pressure - RA pressure RV systolic pressure =TR peak velocity + RA pressure 57
Pulmonary Artery Pressure TR peak velocity = RV systolic pressure - RA pressure RV systolic pressure =TR peak velocity + RA pressure PA systolic pressure 58
Pulmonary Artery Pressure TR peak velocity = RV systolic pressure - RA pressure RV systolic pressure =TR peak velocity + RA pressure IVC inspiratory collapse >50% RA pressure = 10 mmhg <50% RA pressure = 14-20 mmhg 59
RA Pressure Approximation by 2-D Examination of the IVC 60
RV Systolic Pressure RVSP = 55 mmhg + 5 mmhg 61 Cardiol Clin 1990;8:277-87
PA Diastolic Pressure PA end-diastolic pressure = 4 x (PR end-diastolic velocity) 2 + RAP 62
Thank you for your kind attention 63