introduction to echocardiography 2

8/6/2019 Introduction to Echocardiography 2

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Introduction to

EchocardiographyCardiac Ultrasound

Pauline Seydak

Clinical Physiology Trainer NI


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Echo

Echo is something you experience allthe time. If you shout into a well, theecho comes back a moment later. Theecho occurs because some of thesound waves in your shout reflect off asurface (either the water at the bottom

of the well or the wall on the far side)and travel back to your ears. A similarprinciple applies in cardiac ultrasound.


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Generation Of An Ultrasound

ImageEchocardiography (echo orechocardiogram) is a type ofultrasound test that uses high-

pitched sound waves to produce animage of the heart. The soundwaves are sent through a devicecalled a transducer and arereflected off the various structures

of the heart. These echoes areconverted into pictures of the heartthat can be seen on a videomonitor.There is no special preparation for

the test.


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Cont.Ultrasound gel is applied to thetransducer to allowtransmission of the soundwaves from the transducer tothe skin

The transducer transforms theecho (mechanical energy) intoan electrical signal which is

processed and displayed as animage on the screen.

The conversion of sound toelectrical energy is called the

piezoelectric effect


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Machines

There are 5 basic components of an ultrasound scanner thatare required for generation, display and storage of anultrasound image.

1. Pulse generator - applies high amplitude voltage toenergize 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 ofmodes

5. Memory - stores video display


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Transthoracic EchoA standard echocardiogram is also knownas a transthoracic echocardiogram (TTE),or cardiac ultrasound.

The subject is asked to lie in the semirecumbent position on his or her left sidewith the head elevated.

The left arm is tucked under the head and

the right arm lies along the right side ofthe body

Standard positions on the chest wall areused for placement of the transducer

called echo windows


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Parasternal Long-Axis View

(PLAX)Transducer position: leftsternal edge; 2nd 4th

intercostal spaceMarker dot direction: pointstowards right shoulder

Most echo studies begin with

this view

It sets the stage forsubsequent echo views

Many structures seen fromthis view


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Parasternal Short Axis View

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

Marker dot direction: pointstowards left shoulder(900

clockwise from PLAX view)

By tilting transducer on an axis

between the left hip and rightshoulder, short axis views areobtained at different levels,from the aorta to the LV apex.

Many structures seen


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PapillaryM

uscle (PM

)levelPSAX at the level ofthe papillary musclesshowing how the

respective LVsegments areidentified, usually forthe purposes ofdescribing abnormalLV wall motion

LV wall thickness canalso be assessed


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Apical 4-Chamber View

(AP4CH)Transducer position:apex of heart

Marker dot direction:

points towards leftshoulder

The AP5CH view isobtained from this

view by slight anteriorangulation of thetransducer towardsthe chest wall. TheLVOT can then be

visualised


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Apical 2-Chamber View

(AP2CH)Transducer position: apexof the heart

Marker dot direction:points towards left side ofneck (450 anticlockwisefrom AP4CH view)

Good for assessment of

LV anterior wall

LV inferior wall


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SubCostal 4 Chamber

View(SC4CH)Transducer position: under thexiphisternum

Marker dot position: pointstowards left shoulder

The subject lies supine with headslightly low (no pillow). With feeton the bed, the knees are slightlyelevated

Better images are obtained withthe abdomen relaxed and duringinspiration

Interatrial septum, pericardialeffusion, desc abdominal aorta


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Suprasternal ViewTransducer position: suprasternalnotch

Marker dot direction: points

towards left jawThe subject lies supine with theneck hyperexrended. The head isrotated slightly towards the left

The position of arms or legs andthe phase of respiration have nobearing on this echo window

Arch of aorta


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Valves of the HeartHeart valves maintain theunidirectional flow of blood in theheart by opening and closingdepending on the difference inpressure on each side. There arefour valves in the heart

The two atrioventricular (AV)valves between the atria and theventricles.

The two semilunar (SL)valves, obvious in the arteriesleaving the heart.


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Atrioventricular valves (AV)These are small valves that prevent backflow from the ventriclesinto the atria during systole. They are anchored to the wall of theventricle by chordae tendineae, that prevent the valve frominverting.

The chordae tendineae are attached to papillary muscles thatcause tension to better hold the valve. Together, the papillarymuscles and the chordae tendinae are known as the subvalvularapparatus. The function of the subvalvular apparatus is to keepthe valves from prolapsing into the atria when they close. Thesubvalvular apparatus have no effect on the opening and closureof the valves. This is caused entirely by the pressure gradientacross the valve.

AV valves are Mitral and Tricuspid


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Mitral Valve (

MV)

Also known as the bicuspidvalve contains two flaps. The

mitral valve gets its name fromthe resemblance to a bishop'smitre (a type of hat). It allowsthe blood to flow from the leftatrium into the left ventricle.It is on the left side of the heartand has two cusps or leaflets, theAnterior MV leaflet (AML) andthe Posterior MV leaflet (PMV)


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Tricuspid Valve (TV)The tricuspid valve is the threeflapped valve on the right side ofthe heart, between the rightatrium and the right ventriclewhich stops the backflow of bloodbetween the two.

This valve consists of 3 leaflets alarge anterior leaflet (ATL), asmall septal leaflet (STL) and atiny posterior leaflet (PTL)


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Semilunar ValvesThese are positioned on thepulmonary artery and theaorta. The semilunar valves areflaps of endocardium and

connective tissue reinforced byfibers which prevent the valvesfrom turning inside out. They areshaped like a half moon, hence

the name semilunar Thesevalves do not have chordaetendinae.

They are namedAortic and

Pulmonary


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Aortic Valve (AV)Lies between the left ventricle and theaorta and has three cusps,

anteriorright coronary cusp (RCC)

posteriornon-coronary cusp (NCC)middle left coronary cusp (LCC)

During ventricularsystole, pressure

rises in the left ventricle. When the

pressure in the left ventricle rises

above the pressure in the aorta, the

aortic valve opens, allowing blood to

exit the left ventricle into the aorta.


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Pulmonary Valve (PV)Lies between the right ventricle and thepulmonary artery and has three cusps a

posterior (left) cusp, an anterior cusp and a

right cusp.Similar to the aortic valve, the pulmonary

valve opens in ventricular systole, when the

pressure in the right ventricle rises above the

pressure in the pulmona

rya

rtery. At the endof ventricular systole, when the pressure in

the right ventricle falls rapidly, the pressure

in the pulmonary artery will close the

pulmonary valve.


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Systole/Diastole


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TheM

odalities of EchoThe following modalities of echo are used clinically:1. Conventional echo

Two-Dimensional echo (2-D echo)Motion- mode echo (M-mode echo)

2. Doppler EchoContinuous wave (CW) DopplerPulsed wave (PW) Doppler

Colour flow(CF) Doppler

All modalities follow the same principle of ultrasoundDiffer in how reflected sound waves are collected and analysed


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Two-Dimensional Echo

(2-D echo)This technique is used to "see" the

actual structures and motion of the

heart structures at work.

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 display screen.

A 2-D echo view appears cone-sha ed on the monitor.


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M-M

ode echocardiographyAn M- mode echocardiogram isnot a "picture" of the heart, but

rather a diagram that shows how

the positions of its structures

change during the course of thecardiac cycle.

M-mode recordings permit

measurement of cardiac

dimensions and motion patterns.

Also facilitate analysis of time

relationships with other

physiological variables such as

ECG, and heart sounds.


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Doppler echocardiographyDoppler echocardiography is a

method for detecting the directionand velocity of moving blood withinthe heart.

Pulsed Wave (PW) useful for low

velocity flow e.g. MV flowContinuous Wave (CW) useful forhigh velocity flow e.g aortic stenosis

Color Flow (CF) Different colors are

used to designate the direction ofblood flow. red is flow toward, andblue is flow away from thetransducer with turbulent flow shown

as a mosaic pattern.


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ConclusionEchocardiography provides a substantialamount of structural and functionalinformation about the heart.

Still frames provide anatomical detail.

Dynamic images tell us aboutphysiological function

The quality of an echo is highly operatordependent and proportional toexperience and skill, therefore the valueof information derived depends heavilyupon who has performed it

introduction to echocardiography 2

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