echocardiography for the surgeons

7/30/2019 Echocardiography for the Surgeons

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Echocardiography for the

Surgeons

Dr. Rezwanul Hoque BulbulMS, FCPS, FRCSG, FRCSEd

Associate ProfessorBSM Medical University, Dhaka

Bangladesh


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General concepts

The use of ultrasound toexamine the heart- a safe,powerful, non-invasive andpainless technique

Sound is the disturbance

propagating in a material Frequency is the

oscillations per second

Frequency higher than20KHz can not beperceived by ear- known as

ultrasound Echo uses frequency range

1.5MHz to 7.5 MHz, upto15MHz for skin lesion.


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Basic concepts of US

Velocity of sound- in heart 1540m/s, in air 330m/s

Velocity divided by frequency gives wave length

Shorter the wavelength, higher is the resolution,

greater is the penetrationPiezoelectric crystals converts electricaloscillation to mechanical oscillation to produceUS, opposite occurs when same crystal acts as

receiverThe repetition rate is 1000/s, transmission 1micro sec, remaining time spent in receivingmode


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Probe-types for 2-D1.Mechanical sector scanner

2.Phased array sector scanner


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Machines

There are 5 basic components of an ultrasound scanner that are

required for generation, display and storage of an ultrasound

image.1. Pulse generator - applies high amplitude voltage to energize the

crystals

2. Transducer - converts electrical energy to mechanical (ultrasound)energy and vice versa

3. Receiver - detects and amplifies weak signals

4. Display - displays ultrasound signals in a variety of modes

5. Memory - stores video display


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Viewing the Heart

Windows allow good

penetration by US withouttoo much masking by Lung

or ribs

Echo may be difficult in

those with chest wall

deformity, COPD, lungfibrosis, obese person

Axis refers to the plane in

which the US beam travels

through the heart


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Echo windows & views

Left parasternal window( 2nd-4th ICS,

left sternal edge)

Long axis view,

Short axis view(AV, MV,LV Papillary muscle,LV apex level)

Apical window

4 chamber ,5 chamber( aortic outflow) , Longaxis & 2 chamber view

Subcostal window- useful in lung

disease

Supracostal window

Right parasternal window


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Parasternal Long-Axis View (PLAX)

Transducer position: left sternaledge; 2nd 4th intercostal space

Marker dot direction: pointstowards right shoulder

Most echo studies begin with thisview

It sets the stage for subsequentecho views

Many structures seen from this

view


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Parasternal Short Axis View (PSAX)

Transducer position: left sternal edge; 2nd

4th intercostal space

Marker dot direction: points towards leftshoulder(900 clockwise from PLAX view)

By tilting transducer on an axis between theleft hip and right shoulder, short axis viewsare obtained at different levels, from theaorta to the LV apex.

Many structures seen


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Papillary Muscle (PM)level

PSAX at the level of thepapillary muscles showinghow the respective LVsegments are identified,usually for the purposes ofdescribing abnormal LV wallmotion

LV wall thickness can also be

assessed


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Apical 4-Chamber View (AP4CH)

Transducer position: apex ofheart

Marker dot direction: pointstowards left shoulder

The AP5CH view is obtained fromthis view by slight anteriorangulation of the transducertowards the chest wall. The LVOTcan then be visualised


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Apical 2-Chamber View (AP2CH)

Transducer position: apex of the heart

Marker dot direction: points towardsleft side of neck (450 anticlockwise

from AP4CH view)

Good for assessment of

LV anterior wall

LV inferior wall


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Apical 5-chamber view


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SubCostal 4 Chamber View(SC4CH)

Transducer position: under thexiphisternum

Marker dot position: points towards leftshoulder

The subject lies supine with head slightly

low (no pillow). With feet on the bed, theknees are slightly elevated

Better images are obtained with theabdomen relaxed and during inspiration

Interatrial septum, pericardial effusion,

desc abdominal aorta


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Suprasternal View

Transducer position: suprasternal notch

Marker dot direction: points towards left jaw

The subject lies supine with the neckhyperextended. The head is rotated slightly

towards the left

The position of arms or legs and the phase ofrespiration have no bearing on this echowindow

Arch of aorta


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Echo Techniques

2-D echo

M-mode echo

Pulsed wave Doppler

Continuous wave Doppler

Color flow mapping

Stress echo

3-D echo

Preoperative

Intraoperative

Postoperative

Transthoracic echo

Trans oesophageal echo


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Diastole/ Systole in echo


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2-D echo

Gives a snapshot in time of a cross-section of

tissue

Ultrasound is transmitted along several scan

lines(90-120), over a wide arc(about 900) and

many times per second.

The combination of reflected ultrasound

signals builds up an image on the displayscreen.

This technique is used to "see" the actualstructures and motion of the heart structures atwork.

Real-time imaging is possible if the scanningand display is rapid

Sector imaging is possible either by

mechanical rotation of a transducer or phasedelectric stimulation of array of crystals

Anatomy, chamber size, intra & extra cardiacmass, fluid collection

Ventricular and valvular movement

A 2-D echo view appears cone-shaped on the

monitor.

Positioning for M-mode and Doppler echo


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M-mode echo( 1-D echo)

Motion mode echo is produced by

transmission and reception of US along

only one line

An M- mode echocardiogram is not a

"picture" of the heart, but rather a

diagram that shows how the positions of

its structures change during the course of

the cardiac cycle.

M-mode recordings permit measurement

of cardiac dimensions and motion

patterns.

Also facilitate analysis of timerelationships with other physiological

variables such as ECG, and heart

sounds.

More sensitive than 2-D echo in imaging

moving object


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Distance

Systole

M-mode at Mitral Valve

Diastole

Time


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Systole


Diastole

dc

a

f

e

d

Time

Distance


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Systole


Diastole

e

d Time

Distanced-e

amplitude


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Systole


Diastole

Septum

e

Time

DistanceEPSS


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Systole


Diastole

e

d Time

Distanced-e slope


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Systole


Diastole

f

e

Time

Distancee-f slope


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M-mode at the Mitral Valve

Amplitude DescriptionNormal

Value

EPSS Measure e point to septal

separation

< 5 mm

d-e Measures the maximum

excursion of the mitral valve

following diastolic opening.

17 to 30 mm


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M-mode at the Mitral Valve

Slope Description Normal Value

d-e Measure rate of initialopening of the mitral valve

in early diastole.

240 to 380mm/s

e-f Measures the rate of early

closure of the mitral valve

following diastolic opening.

50 to 180 mm/s


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Distance

Systole


Diastole

Time

Systolic anterior motionof the AMVL


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Distance

Systole


Diastole

Time

MV prolapseposterior leaflet


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M-mode at the Aortic Valve

Coronarycusp

Non-coronary cusp

Anterior aortic root

Posterior aortic root

Left Atrium


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M-mode at the Aortic Valve

LA dimension

Cusp SeparationAortic root


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Assessment of Severity

Maximal aortic cusp separation(MACS) on M-mode

Vertical distance between RCC andNCC during systole

Stenotic Aortic Valve decreasedMACS

Limitations

Single dimensionAsymmetrical AV involvement

Calcification / thickness

LV systolic function

CO status

AVA MACS

N > 2cm2 N > 15 mm

< 0.75 cm2 < 8 mm

> 1 cm2 > 12 mm

gray area 8 12 mm


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M-mode at Left Ventricle

LVPWd

IVS

RVIDd/RVIDs

LVIDd/LVIDs


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M-mode LV Calculation

FS = LVIDd LVIDsLVIDd

EF = LVIDd3 LVIDs3LVIDd3

IVS % thickening = (IVSs IVSd) x 100IVSd

LVPW % thickening = (LVPWs LVPWd) x 100LVPWd

LV Mass = 1.04 {(LVIDd + IVSd + LVPWd)3 (LVIDd)3} x 0.8 + 0.6g


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E-F slope

The two mitral leafletsmove in diastole in M-

shaped mirror image

pattern. At the onset of

systole the two leaflets

come together sharply toproduce the 1st heart

sound. The early diastolic

velocity of the leaflets,

called the E to F slope is

dependent on the rate ofLV filling. The velocity may

be slowed when the rate of

filling is slowed( MS).


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LV SYSTOLIC FUNCTION

Quantitative echo

LV VOLUME

LV MASS

EJECTION INDICES

STROKE VOLUME

EJECTION FRACTIONFRACTIONAL SHORTENING

VELOCITY OF CIRCUMFERENCIAL FIBRE

SHORTENING


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Quantify LV function -MODES

M-Mode

Modified Simpsons Method Single plane area-length method

Velocity of Circumferential Shortening

Mitral Annular Excursion

E-point to septal separation

Rate of rise of MR jet

Index of myocardial performance

Subjective assessment


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Fractional shortening

Fractional shortening (FS) is the fraction of any diastolic dimension

that is lost in systole. When referring to endocardial luminal

distances, it is EDD minus ESD divided by EDD (times 100 when

measured in percentage).

Normal values may differ somewhat dependent on which

anatomical plane is used to measure the distances, but a rangefrom 30 to 42% is considered normal with 26 to 30% representing a

mild decrease in function.

Midwall fractional shortening may also be used to measure

diastolic/systolic changes for inter-ventricular septal dimensions and

posterior wall dimensions. However, both endocardial and midwall

fractional shortening are dependent on myocardial wall thickness,and thereby dependent on long-axis function.

By comparison, a measure of short-axis function termed epicardial

volume change (EVC) is independent of myocardial wall thickness

and represents isolated short-axis function.


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In cardiovascular physiology, ejection

fraction (EF) represents the volumetric

fraction of blood pumped out of the

ventricle (heart) with each heart beat orcardiac cycle. It can be applied to either

the right ventricle which ejects via the

pulmonary valve into the pulmonary

circulation or the left ventricle which

ejects via the aortic valve into the

systemic circulation. Ejection fraction

(Ef) is the fraction of the end-diastolic

volume that is ejected with each beat;that is, it is stroke volume (SV) divided

by end-diastolic volume (EDV):Tests for measuringEF:

Echocardiogram

MUGA scan

CAT scan

Cardiac catheterization

Nuclear stress test

Measure Typical value Normal rangeend-diastolic volume (EDV)120 mL[1] 65240 mL

end-systolic volume (ESV) 50 mL 16143 mL

stroke volume (SV) 70 mL 55100 mL

ejection fraction (Ef) 58% 5570%[2]

heart rate (HR) 75 bpm 60100 bpm

cardiac output (CO) 5.25 L/minute 4.08.0 L/min

Depends on contractility, preload and

afterload, heart rate, synchronicity ofcontractions

Global parameter, regional differences incontractility averaged

LV ejection fraction


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LVEF

Qualitative - visual

inspection

severity: mild, moderate,

severe

focality: global

reported as a range in

intervals of 5-10%

regional: 17 segments

Quantitative

accuracy, reproducibility

limited

assumes shape of LV cavity

best in symmetric ventricles


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Simpsons Rule the biplane method

of disks

Volume left ventricle

- manual tracings in systole and

diastole

- area divided into series of

disks

- volume of each disk ( r2 * h )

summed = ventricular

volume

LV-ED LV-ES

A4C

A2C


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Simpsons Rule the biplane

method of disks

Once volumes determined, EF is calculated :

LV diastolic volume - LV systolic volume x 100%LV diastolic volume

Normal > 50%, 35 to 50% moderately

depressed,


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LVEF-other echocardiographic

method

Echocardiographic methods included:1. Cubed M-mode formula

2. Teichholz M-mode formula

3. Subjective estimation of LVEF from two-dimensional

videotape4. Area-length method in one four-chamber view

5. Average of area-length method in three four-chamber

views

6. Average of area-length method in four-chamber and two-

chamber views (one beat each)7. Subjective estimation from stored videoloop of four-

chamber and two-chamber view


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Diastolic Dysfunction

Diastolic Dysfunction

Equates to reversed E/A ratio(smaller E wave - taller Awave)


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L f i l bi l l


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Formulas andCalculationsBiplane volume & ejection fraction

(Area/length 2D axes )Left ventricular mass, 2D

Circumferential end-systolic wall stress

Preload

Left ventricular segmental wall motion

Left atrial biplane volume

Left atrial appendage shear rate of bloodLong / short axis ratio

Mitral valve percent calcification

Mitral score

Left ventricular biplane volume(Area/length,Dodge correction)(area planimetry1 x area

planimetry2 x 8) / (3 x xsmallest long axis) (ml)

Transthoracic parasternal short axis viewA1 Red: tracing of pericardial borderA2 Green: tracing of endocardial border (papillarymuscles are excludedAm = A1 - A2 = area of myocardiumt: myocardial thickness (automatically calculated bythe software)LV mass index (truncated ellipsoid) normal values:Males: 7613 gm/m2Females: 6611 gm/m2


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Valve area calculation

1 Planimetry

2 The continuity equation

3 The Gorlin equation

4 The Hakki equation5 Real-time three-

dimensional

echocardiography

Gorlin Formula
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The Doppler shift (Fd) of

ultrasound will depend on

both the transmitted

frequency (fo) and thevelocity (V) of the moving

blood. This returned

frequency is also called the

"frequency shift" or

"Doppler shift" and is highlydependent on the angle of

ultrasound beam from the

transducer and the moving

red blood cells. The

velocity of sound in blood

is constant (c)


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Spectral analysis

The difference in waveformbetween the transmitted andbackscattered signal iscompared.

A process called fast Fouriertransform (FFT) displays this

information into a spectralanalysis (spectral display ofentire range of velocities)

Time- x axis

Velocity- y axis

Toward the transducer is

positive, away from transducernegative.

Amplitude is displayed asbrightness of the signal.


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AliasingCorrected by:-

Increasing the pulse repetitionfrequency(PRF)

Decreasing the transmitted

frequency


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CW Doppler echo PW Doppler echo

A single crystal is used for

transmitting and receiving US Depth is measured by

multiplying half of time delaywith velocity of sound in thetissue

Can localize the site of flowdisturbance

Detects normal valve flowpattern

LV diastolic function

Measurement of stroke volumeand cardiac output

Can not measure velocity > 2m/s

Two crystals- one

transmitting anotherreceiving continuously are

used

Measures high velocity but

can not localize depth and

width precisely

Detects severity of valvular

stenosis, valvular

regurgitation and velocity of

flow in shunts


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Color flow mapping

2-D version of PW Doppler with color coding

Velocity away from transducer is blue, towards

it is red( BART), green applied to mosaic flow

Higher velocity appears lighter, color reversaloccurs above a threshold velocity

Used for assessment of shunt or regurgitation

CW & PW Doppler allow graphical

representation of velocity against time knownas spectral Doppler


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Color Doppler

Displayed as color information-Amplitude- intensity

Direction- red vs. blue (toward or away from

transducer)Velocity- brightness (bright blue higher velocity)

Variance (turbulence)- coded green to give amosaic appearance.

Overlays this information on 2D images

Time consuming (temporal resolution isespecially poor with a large sector window)

Different vendors have different algorithmsfor generating color Doppler


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Tissue Doppler Imaging

Routine Doppler targets blood flow High velocity

Low signal amplitude

Tissue Doppler (assessing the

movement of the myocardium)

targets tissue Low velocity

High signal amplitude

Different Filters

Velocity of tissue along a particular

sample volume

Color-TDI, Velocity of tissue

coded by color superimposed on

2-D image . Can derive

information such as strain, strain

rate, dyssynchronyetc.

Trans oesophageal echocardiography


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This is an alternative way to perform an

echocardiogram. A specialized probe

containing an ultrasound transducer at its

tip is passed into thepatient's oesophagus. This allows image

and Doppler evaluation from a location

directly behind the heart.

Transesophageal echocardiograms are

most often utilized when transthoracic

images are suboptimal and when a more

clear and precise image is needed for

assessment.

p g g p y


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C li ti d t t d ith


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Complications detected with

Intraoperative TEE

Intracardiac air

Intracavitary

Intercavitary

Myocardial

Individual targets

Ventricular dysfunction

Left ventricle

Right ventricle

Following valvular replacement Paravalvular regurgitation

Outflow tract obstruction


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Prosthetic Valve Pathology

Prosthetic Valve Regurgitation

Aortic Mitral

Prosthetic Valve Stenosis

Aortic

Mitral


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Bioprosthetic valves

Mitral Position

2-D ECHOCARDIOGRAPHIC APPEARANCE


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Special Problems of 2-D Imaging

Artificial Valves

Echocardiographs are calibrated to measure distance based on the

speed of sound in tissue.

Prosthetic valves have different acoustic properties than tissue. Hence,

distortion of:

Size

Location, and

Appearance, of the prosthesis.


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Indices of Valve Stenosis which

are less flow dependent

A. Contour of jet velocity

B. Doppler velocity index

C. Effective orifice area

D. Valve resistance


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A-Contour of the jet velocity

With prosthetic obstructionthere is:

Late peaking of the velocity,

More rounded contour,

Prolonged ejection.


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Prosthetic Valve Regurgitation

Physiologic Regurgitation

Early onsetand brief duration

Reflects backflow from closing movement of

occluding device

Tilting disc and bileaflet valves have additional late

backflowleakage

Intended to reduce risk of thrombosis


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Mitral Prosthesis Regurgitation

TTE of limited value in assess MR due to acoustic

shadowing of the LA

Doppler findings suggestive of severe MR

E wave > 1.9 m.s

PISA

Short isovolumetic relaxation timeTVILVOT/TVIPr-MV < 0.4

Normal values for adult


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Normal values for adult

LVIDs End systole 2.0-4.0 cm

LVIDd End diastole 3.5-5.6 cm

Wall thickness

Diastolic Septum

Post wall

0.6-1.2 cm

0.6-1.2 cm

Systolic Septum

Post wall

0.9-1.8 cm

0.9-1.8 cm

FS 30-45%

EF 50-85%

LAD 2.0-4.0 cm

Aortic root diameter 2.0-4.0 cm

RV diameter 0.7-2.3 cm


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Range MeanIVS wall thickness (cm) 0.6-1.1 0.9 0.4

Aortic root dimension (cm) 2.0-3.5 2.4 0.4Aortic cusps separation (cm) 1.5-2.6 1.9 0.4Percentage of fractional

shortening 34-44% 36%

Mitral flow (m/s) 0.6-1.3 0.9Tricuspid flow (m/s) 0.3-0.7 0.5Pulmonary artery (m/s) 0.6-0.9 0.75

Aorta (m/s) 1.0-1.7 1.35

The Bernoulli equation is a


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The Bernoulli equation is a

complex formula that

relates the pressure drop

(or gradient) across anobstruction to many factors

For practical use in

Doppler echocardiography

this formula has been

simplified to:

p1-p2=4V2


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Echo-Doppler estimates of flow volume are based upon aknowledge of the area of flow (from echocardiogram) and thelength (from Doppler). It is assumed that the aorta is a cylinder.Doppler estimates of cardiac output compare quite favourably

with those obtained by other methods.

Pulmonary valve disease


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Idealized spectralrecordings demonstratingthat time-to-peak velocity isvery rapid in patients withpulmonary hypertension.

CW Doppler spectral velocity recordingof mild pulmonic stenosis and insufficiency.The abnormal diastolic flow toward thetransducer of pulmonic insufficiency iseasily recognized. (Scale marks = 1m/s)

Flow towards the transducer gives positive waves, away from transducer negative deflection


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Aortic stenosis


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PW Doppler spectral recording ofaortic blood flow (arrow) takenfrom the apical window.

Note the laminar appearance ofnormal flow. (Scale marks = 20cm/s)

CW spectral recording from theapex in a patient with aorticstenosis. The velocity spectrumis broadened and systolicvelocity is increased to 4 m/s.

(Scale marks = 2 m/s)


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The duration of mitral insufficiency is

ll l th th t f


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Aortic stenosis (left) should not bemistaken for mitral insufficiency(right). Mitral systole begins beforeaortic (arrow) and is longer induration. (Scale marks = 2m/s)

generally longer than that of

aortic stenosis, partly because the

time from mitral valve closing to

opening is longer than for aorticvalve opening to closing. Similarly,

the duration of aortic insufficiency is

longer than mitral stenosis because

the time from aortic valve closing to

opening is longer than for mitral

valve opening to closing. Similarrelationships are true of the pulmonic

and tricuspid valve on the right side

of the heart.

Left panel shows an aortic stenotic jetin relation to possible viewingdirections using CW Doppler. Rightpanel shows spectral velocity tracingsfrom each respective window. The bestrecording is from the right sternal

window. (Calibration marks = 2m/s)


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The severity of aortic stenosis may also be

judged by the relative proportion of totalsystolic time taken to reach peak velocity(stippled areas). Both time to peak and peakvelocity are lower in panel A than in panel B.((Scale marks = 1m/s)

Continuity of forward flow. Flow thatenters a cylinder is equal to the flowpassing through an obstruction andexiting from the distal side.


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Tricuspid stenosisPulmonary stenosis

Coarctation of Aorta HOCM

VSD


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echocardiography for the surgeons

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