Transcript echocardiography

ECHOCARDIOGRAPHY
Presented by ; Dr.Manoj Chandel
Moderated by; Dr.Yashwant
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Definition
Properties of ultrasound
Principles of image optimization
Doppler shifts
TTE
TEE; PROCEDURE,INDICATIONS,
APPLICATIONS,CONTRAINDICATIONS,COMPLIC
ATIONS,ADVANTAGES
ECHO
• Also known as cardiac ultrasound
• Uses sound waves to create pictures of
heart.It uses standard ultrasound tech to
image 2D slices of heart.The latest ultrasound
sys. 3D real time imaging
• The test gives information about size and
shape of heart and how well heart chambers
and valves are working
• The test also identify areas of heart ms that
are not contracting normally due to poor
blood flow or injury from previous heart
attack
• Helps in calculation of C.O as well as ejection
fraction,cardiac dimensions
• A type of echo called doppler ultrasound
shows how well blood flows through the
chambers and valves of heart
• Echo can detect possible blood clots inside the
heart,fluid build up in the pericardium and
problems with the aorta
• Echo was the 1st appl of i.v contrast enhanced
ultrasound
PROPERTIES OF USG
• USG machine generates an imperceptible
vibration within a transducer(device that converts
energy from one form into other) that when put
next to tissue surfaces, vibrates the surrounding
tissue( musle , blood, fat or bone)
• During vibration particles within the tissue
compress and then spread apart. This dual
process is called compression and rarefaction
• The sequence of compression and rarefaction is
described by sine waves and is characterised
• In terms of
wavelength,frequency,amplitu
de and propagation vel.
• Wavelength: distance between
2 peaks of sine waves
• Frequency:no.of cycles in
1second
• Amplitude:measure of tissue
compression.It represents
loudness of USG wave in dB
• Propagation vel.;describes
speed of USG wave travelling
through tissue.In blood it is
1500m/s
• Propagation vel=wavelength x
frequency
• Transducers ,typically made of
quartz or titanate ceramic use
crystals that exhibit
piezoelectric effect
• With electricity,crystal vibrates
and emits USG.The reverse
also holds i.e when USG wave
strikes a piezoelectric crystal
and make it vibrate,the crystal
generates electricity.Thus the
same crystal can serve as
emitter and receiver of USG
• ECHO uses ultrasound waves with frequency
2.5-7.5 million cycles/sec. Slower the
Freq,greater the depth of penetration and
faster the freq,greater the resolution
• Freq>7.5 Hz are not used as they produce
wavelength too short for adequate
penetration into tissue
BASIC PRINCIPLES OF IMAGE
OPTIMIZATION
• In ECHO,the crystals emits very short pulses of
ultrasound(0.5-3micro sec)and receive
reflected USG for 250-500 micro sec.
• The pulse repitition frequency(PRF)is the no.of
pulses that leave and return the transducer in
1 sec
• As image depth is increased,the time required
to reach the target depth and return increases
and PRF decreases
• PRF is described in Hz.,it is audible and ranges
1-10 kHz
• Early echo displays used this principle to map
out depth of structures within heart. The 1st
echo motion studies were 1-D views of cardiac
st. produced by single crystal transducers with
the results traced on moving photosensitive
paper
• Today it is used to view rapidly moving st. such
as valve leaflets as it can produce upto 1800
images/sec
• However it reveals only a small portion of
heart at one time
• To generate 2D images ultrasound machines
were configured to sequentially redirect the
beam over an area of interest
• Although 2D tech produce only 30
images/sec,it provides enormous adv. in
recognising anatomic and pathologic
landmarks
• Matrix array transducers solved the image
acquisition problem.They contain over 3000
imaging elements and electronically rotate 2D
usg beam 180 degree in millisec. To acquire
the requisite 2D image in a fraction of time
DOPPLER EFFECT
• Defined as the apparent change in the freq. of
waves(sound or light) when the source and
observer are in motion relative to each
other,with the freq. increasing when source
and observer approach each other and
decreasing when they move apart
• When applied to echo,it provides a significant
enhancement to 2D imaging
• With doppler, blood flow vel. can be measured
as blood flows through structures inside
heart.The USG that bounces off moving RBCs
is reflected back to transducer at a slightly
different freq. than that emitted from
transducer
• The shift in freq allows the USG machine to
estimate blood flow vel. and direction of flow
• Doppler shifts are
presented in 3 ways
• 1.PWD
• 2.CWD
• 3.CFD
• With PWD,a small sampling
vol(cursor)is placed in an
area of interest within 2D
image. Transducer
generates a pulse of USG
and then switches to the
receive mode and awaits
the arrival of reflected
portion of USG pulse
• Ultrasound machine then
measures freq. shift(Doppler
shift)
• Limitation: too slow to capture
the vel. of fast moving blood
cells(aliasing)
• CWD: uses 2 separate
transducers,one to
continuously emit USG and
one to receive it. However
infinite pulse repition rate
allows insufficient time for 1st
pulse to return to transducer
before next is emitted
• and so ultrasound machine
cannot precisely define the
location of moving blood
cells
• CFD: based on PWD and
uses multiple sample
vol.along a scan line
• A color code is used to
depict flow toward(red) and
away(blue) from the
transducer. Lighter and
darker shades of red and
blue denote relatively faster
and slower vel.
• TISSUE DOPPLER: new use of PWD tech to
measure myocardial vel. Instead of blood flow
vel.
• During LV contraction,mitral annulus descends
towards the apex of heart.Tissue doppler imaging
measures vel. of this descent(Sm) and
(Sm)correlates with traditional measures of LV
fun.
• Sm decreases in myocardial ischemia
• 4 chamber c.s view is best for measuring Sm
TRANSTHORACIC ECHO
• A standard echo is called TTE.
• In this case,the echo transducer or probe is
placed on the chest wall and images are taken
through the chest wall
• Non invasive,highly accurate and quick
assessment of overall health of heart
• Accuracy reduced by obesity,copd,chest wall
deformities
• Bubble contrast TTE involves the injection of
agitated saline into a vein followed by echo
study.The bubbles are initially detected in RA
and RV. IF bubbles appear in left heart, this
indicates shunt PFO,ASD,VSD,AV malformation
TEE
• Recommended if regular or transthoracic echo
is unclear or when a much clearer picture of
certain areas of heart is needed
• PROCEDURE;
• Patient is anaesthetised,trachea
intubated,contents of stomach are suctioned
• Gentle massage of left upper quadrant of abd.
during suction removes air which can
otherwise degrade imaging
• Patient neck extended and well lubricated TEE
probe introduced into midline of hypopharynx
with transducer side facing anteriorly.
• Laryngoscope is used to lift larynx anteriorly
and probe is placed into oesophagus
• During insertion or withdrawl of transducer
,the controls of gastroscope must be in neutral
or relaxed position to allow the transducer to
follow the natural course ,minimising injury.
• TEE provides extremly valuable information
about cardiac anatomy and function during
surgery
• 2D,multiplane TEE can detect regional and
global ventricular abnormalities,chamber
dimensions,valvular anatomy and presence of
intracardiac air
• It can also be helpful in confirming
cannulation of coronary sinus for cardioplegia
• Multiple views can be taken from upper and mid
oesophagus and transgastric positions. Two most
commonly used views for monitoring during
cardiac surgery are 4 chamber view and
transgastric view (short axis)
• The advent of live 3D echo offers great promise
for better visualisation of complex anatomic
features,assessment of valvular fun and
assessment of regional/global fun.
Indications of Perioperative TEE
• Category 1:supported by strongest evidence or
expert opinion;TEE is frequently useful in
improving clinical outcome
• Intraoperative evaluation of acute,persistent and
life threatening hemodynamic disturbances in
which ventricular function and its determinants
are uncertain and have not responded to
treatment
• I/O use in valve repair
• I/O use in CHD surgery requiring CPB
• I/O use in repair of HOCM
• I/O use in endocarditis
• Preoperative use in unstable patients with
suspected thoracic aortic
aneurysms,dissection or disruption who need
to be evaluated quickly
• I/o assessment of aortic valve function during
repair of aortic dissections with +ve aortic
valve involvement
• I/O evaluation of pericardial window
procedures
• Category2;supported by weaker evidence;TEE
may be useful in improving clinical outcome
• Use in ICU for unstable patients with
unexplained hemodynamic
disturbances,suspected valve disease or
thromboembolic problems(if other tests have
not confirmed the diagnoses)
INDICATIONS OF TEE
• I/O assessment of valve replacement,repair of
cardiac aneurysm,removal of cardiac
tumors,aortic atheromatous disease or other
sources of aortic
emboli,pericardectomy,pericardial effusions or
evaluation of pericardial surg.,anastomotic
sites during heart and lung transplantation
• i/o detection of foreign bodies,air emboli
• i/o use for suspected cardiac
trauma,intracardiac thrombectomy or
pul.embolectomy
• Monitoring placement and fun. Of assist
devices
• Category 3: little current scientific or expert
support;TEE is infrequently useful in improving
outcome
• i/o use ;:during cardiomyopathies other than
HOCM,for uncomplicated
pericarditis,endocarditis
• i/o evaluation of myocardial perfusion,coronary
artery anatomy,graft patency,pleuropulmonary
diseases,repair of thoracic aortic injuries
• i/o monitoring emboli during orthopaedic
proc.,monitoring placement of intraaortic
balloon pump,automatic implantable cardiac
defibrillators or pul. Artery cathetors
APPLICATIONS OF ECHO
• Assessment of ventricular fun.;
• Assessed by global systolic fun.,determined by
• 1. Ejection fraction and LV end diastolic vol.
• 2.,Diastolic fun.(looking for abn. Relaxation
and restrictive distolic patterns by checking
mitral flow vel.)and
• 3. Regional systolic fun.
• 4.Wall motion and thickening abnormalities
• Regional wall abnormalities following
myocardial ischemia often appear before ecg
changes
• Classified into 3 categories
• 1.hypokinesis(reduced wall motion)
• 2.akinesis(no wall motion)
• 3.dyskinesis(paradoxical wall motion)
• Normal LVEF is 55 to 70%, It decreases in
weakness of heart ms(dilated
cardiomyopathy), heart attack, valvular ds.
• LV diastolic fun.:
• Stage 1: impaired(slow) early LV relaxation.
Patient is asymptomatic with normal filling P.
Deceleration time>240sec
• Stage 2: mod. Impaired early LV relaxation
with decreased LV compliance
• Deceleration time=160-240 sec
• Effects of slow early LV relaxation on end
diastolic filling are opposed by elevated LA
pressure and mitral flow vel. return to
normal(pseudonormalisation)
• Symp.; exertional dyspnoea
• Stage 3: restricted filling pattern
• Severe decrease in LV compliance and slow
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early LV relaxation
Filling pressure markedly increased
Deceleration time<160 sec
Symptoms: dyspnoea with min. exertion
APPLICATIONS OF ECHO
• 2.Assessing valvular fun.;
• Valvular morphology can be assessed by
multiplane TEE.Pressure gradients,stenotic valve
area,severity of stenosis and severity of valvular
regurgition can be assessed by Doppler echo and
color flow imaging
• Colours are usually adjusted so that flow towards
the probe is red and flow in the opposite
direction is blue
• TEE can also detect Prosthetic valve dysfun.
Such as obst,regurgition and endocarditis
• TEE images in the upper mid esophagus at 40
to 60 degree and 110 to 130 degree are most
useful for examing aortic valve and ascending
aorta
• Doppler flow across AV must be measured
looking up from TG view
APPLICATIONS OF ECHO
• Mitral valve is examined from ME position in 0
degree and 150 degree view.TEE is an invaluable
aid in MV repair surg
• 3.EXAMINATION OF RESIDUAL AIR
Air is introduced into heart during all open heart
procedures.Residual amounts of air often
remains even after best manaeuvers
TEE is very helpful in detecting residual air so that
additonal surgical manaeuvers can be undertaken
to help avoid cerebral or coronary embolism
4.ASSESSMENT OF OTHER CARDIAC
ABNORMALITIES
TEE can also detect CHD like
PFO,ASD,VSD,Pericardial diseases like
P.temponade and constrictive
pericarditis,cardiac tumors
Doppler color flow imaging helps delineate abn.
Intracardiac blood flows and shunts
• TEE is used to assess the amount of
myomectomy in patients of HOCM
• Upper,mid and LE views arw helpful in
diagnosing aortic ds.(aortic
dissection,aneurysm,atheroma)
• DETECTION OF MYOCARDIAL ISCHEMIA
• Within seconds after onset of myocardial
ischemia,affected segments of heart cease
contracting normally
• In patients undergoing CVS surg,new i/o
SWMA is diagnostic of myocardial ischemia
• ST changes may not occur earliar but SWMA
helps in detecting such changes
• Detection rate of SWMA is more than double
that of ECG
• Not all SWMA are indicative of
ischemia,Myocarditis,MI,Myocardial stunning
also cause SWMA
• LV wall thickness <0.6- Old infarction. If
inotropic stimulation improves SWMA–
Stunning is likely.A sudden severe decrease in
SWMA– Myocardial ischemia
TEE IN NON CARDIAC SURG. AND
CRITICAL CARE
• TEE has a vital role in determining the etiology of the
instability and in guiding vol. resuscitation during
hemodynamic instability and massive blood loss
• Hypotension has only 2 possible causes; Inadequate
C.O or inappropriately low systemic vascular resistance
• TEE is useful in its d/d: During severe
hypotension,qualitative TEE estimates ventricular filling
and fun. And serve as practical guide for
administeration of fluids,inotropes and vasopressors
• In severe LV failure,ventricular filling(assessed
by end diastolic area)is increased and ejection
is decreased,whereas in inappropriately low
systemic vascular resistance ventricular filling
is usually normal or low and ejection is
increased
• Hypovolemia is easily recognised as decrease
in ventricular filling and increase in ejection
VALVULAR DISEASES
• AORTIC STENOSIS
• Degree of AS is appreciated easily in ME AV
SAX cross section(25-45degree with image
depth 10-12cm)where extent of leaflet
opening can be estimated visually or
measured directly by planimetry
• Severe stenosis is characterised by marked
thickening of leaflets and severely reduced
leaflet motion(valve opening area<1sq.cm)
AORTIC REGURGITATION
Degree of AR is best appreciated in ME AV LAX
cross section(110-130 degree).
With color doppler positioned over the leaflets
and outflow tract,AR is recognised as a color
jet emnating from the valve during diastole
MILD AR: diastolic color jet <2mm at its origin in
the valve,that occupies <1/3rd of c.s area of LV
outflow tract and extends min(1-2cm)intoLV
• MOD. AR:
• DCJ 3-5mm,occupying <2/3rd of c.s area of
LVOT and extending 3-5cm into LV
• SEVERE AR: DCJ >5mm,occupying entire LVOT
and extending well into LV
• MITRAL STENOSIS;
• Presense and severity of MS is
seen in ME 4chamber(0degree
with image depth 10-12cm) 2
chamber(90degree with image
depth 14-16cm)or LAX
c.s(135degree)
• 2D imaging reveals thickened
leaflets that dome towards LV
and open poorly
• Color doppler reveals laminar
flow acceleration into stenotic
orifice and turbulent
Normal color doppler aliasing
• Jet emerging into ventricle
• PWD and CWD show
increased peak and mean
vel. Mathematical
calculations from these
traces such as pressure half
time,are the most precise
methods to assess severity
of MS and formulas for
these are built into the
software of each usg
• Severe MS causes marked
LA enlargement and
• LA spontaneous contrast i.e swirling,smokelike
appearance of 1-2mm densities not
attributable to exogenously administered
contrast agents but to aggregation of red cells
in areas of low flow
• Whenever LA enlargement and spontaneos
contrast are noted,THROMBUS in the LA
should be suspected
• MITRAL REGURGITATION
• Severity is evaluated from same c.s as for M.S
• MILD MR: systolic color
jet<2mm,occupies<25%of LA c.s area and
extends<1/2 the distance to post.wall of LA
• MOD.MR; SCJ 3-5mm,occupies<50%of LA c.s
area and extends 50-90%of distance to
post.wall of LA
• SEVERE MR:
• SCJ>5mm,occupies
most of LA and
extending into pul.vein
and LA
• Eccentrically directed
jets of MR that hug the
wall of LA are a/w more
severe valvular
regurgitation than their
c.s area might suggest
Contraindications of TEE
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Absolute C/A
1. previous oesophagectomy
2.severe oesophageal obst.
3.Oesophageal perforation
4.ongoing oesophageal haemorrhage
5.recent upper GI surg
6.Esophageal
diverticulum,varices,scleroderma,stricture
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Relative c/a
Atlantoaxial joint ds.
Mediastinal irradiation
Unexplained swallowing difficulties
Hiatal hernia
COMPLICATIONS
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Odynophagia
Upper GI haemorrhage
Oesophageal perforation
Dental injury
ETT malposition
ADVANTAGES OF TEE OVER TTE
• CLEAR IMAGES
• Heart rests directly upon oesophagus leaving
only few mm that the usg beam has to travel.
This reduces the weakening of usg
signal,generating a stronger return
signal,ultimately enhancing image and
doppler quality
• In TTE usg must traverse skin,fat,ribs and lungs
• All these st. along with increased distance the
beam must travel,weaken the usg signal thus
degrading the image and doppler quality
• In PAEDIATRIC cases TTE has a high degree of
sensitivity for detection of supportive
evidence of endocarditis and TEE should be
reserved for patients with a poor transthoracic
window
THANK YOU