FELLOW SCHOOL:
BASICS OF
ECHOCARDIOGRAPHY
JULY 9, 2014
OBJECTIVES OF THIS TALK:
 Review basics of echocardiography and physics
behind it
 Orient new fellows to reading echoes and basic
interpretation and image acquisition
 Review a normal echo
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WHAT THIS TALK ISN’T…
 In depth discussion of echocardiography physics
 Discussion on how to assess low output aortic
stenosis, differentiating constriction from
restriction, or how we assess for dysynchrony
 In other words, this is echo 101, getting you
through your first day or two….
Why do we perform echoes?
 LV systolic and diastolic function
 RV function
 valvular anatomy / pathology / function
 Aortic pathology
 Pericardial disease
 Intracardiac shunts
 Endocarditis
 Intracardiac thrombus
 Volume status (IVC, RA pressure assessment)
 Pulmonary hypertension
 Mechanical support assessment (LVAD, etc)
 Hemodynamic assessment (Tamponade, constriction, restriction)
 Etc.
How does an ultrasound wave turn into a
picture on a screen?
 Based on fundamental principle of constant
speed of sound in a given medium (1540 m/sec
in tissue or 1.54 mm/usec)
 Ultrasound wave that is received by the
transducer at time (t) after the ultrasound wave
was emitted from crystal, the echo traveled 1.54
x (t) mm, but the object it bounced off of is 0.77
mm (t) away from transducer (round trip)
 This alone can be a full day of lectures….
Beyond the scope of this talk
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How does it work?
How do we do it?
NORMAL ECHO
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 980200396 - normal
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M MODE:
 X axis is time, Y axis is depth from transducer.
 ‘ice pick’ in the heart
 PROS: High temporal resolution
 CONS: Loss of 2D imaging
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CJ Doppler
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Continuous Wave Doppler:
 Doppler is based on physics principal of
an echo returning from a moving object (red
blood cell) creates a shift in frequency
 CW is simplest form of Doppler – one crystal
continually sending signal, another receiving
 Pros: accurately assess high velocity jets;
Confidently obtain the highest velocity in any
given plane
 Cons: Cannot pinpoint where along the plane
the highest velocity occurs (for example, in AS: is
it at the valve, HOCM, subvalvular membrane??
Don’t know with CW)
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CONTINUOUS WAVE DOPPLER (CW):
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Pulse wave doppler:
 Intermittent / episodic emission of echo pulses
from a crystal with reception of signal
intermittently
 PROS: Obtain a velocity at a specific point in
space (ie, in the LVOT or RVOT)
 CONS: Unable to accurately measure high
velocities; aliasing occurs at the Nyquist limit
(important concept)
 Nyquist limit = ½ PRF
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PULSE WAVE DOPPLER (PW):
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 Cos 20 = 0.94
 Cos 30 = 0.86
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Example of aortic stenosis:
 True gradient across aortic valve is mean of 43
mm Hg
 Transducer is parallel to flow. Will measure
gradient at 43 (severe AS)
 Transducer is 20 degrees off. Will measure
gradient at 40 (still severe)
 Transducer is 40 degrees from parallel. Will
measure at 33 (moderate).
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NOW BACK TO COLOR DOPPLER…
 This is a form of pulsed wave Doppler (with all of
the pros and cons)
 However, the cons can actually be used to your
benefit (ie, Nyquist limit, aliasing, and PISA
calculation…)
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Example of exceeding Nyquist limit:
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Tissue Doppler:
 Same principal as PW, change the settings to
focus on velocity of tissue and filter out blood
velocity
 Visualize the S wave (systolic contraction), E
wave (early diastolic relaxation), A wave (atrial
relaxation)
 Used most commonly for assessment of diastolic
dysfunction, LV relaxation, and RV systolic
function.
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RV SYSTOLIC FUNCTION ASSESSMENT:
 Due to abnormal shape of RV, much more
difficult to assess RV size/systolic function
compared to LV
 S wave normal: > 10 cm/s
 TAPSE normal: > 1.6 cm
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IVC assessment:
 Estimate of RA pressure
IVC
Collapse?
RA pressure
< 2.1 cm
Yes
3 (0-5) mm Hg
> 2.1 cm
No
15 (10-20) mm Hg
 If doesn’t fit either of these paradigms, the
pressure is intermediate: 8 mm Hg (5-10 mm Hg)
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EF ASSESSMENT:
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SIMPLIFIED BERNOULLI EQUATION:
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 The change in velocity of blood from a high
pressure system (ie, RV or LV) to a low pressure
system (ie, RA or LA) is directly proportional to
the difference in pressure.
 Due to nearly all of the other variables being very
negligible to the equation, can easily simplify to:
 Change in P = 4V2
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RV systolic pressure assessment:
 P = 4V2
 Can calculate the difference between RV and RA
with CW signal: we know the velocity through the
TV with CW
 Take that number, put in our above equation.
 This only accounts for difference between RV
and RA, so need to add the RA pressure to get
the RV pressure
 RV systolic pressure = 4 (peak TV vel)2 + RA
pressure
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CONTINUITY EQUATION:
 Conservation of mass/energy
 Flow is constant, so if area decreases, velocity
proportionally increases
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Goal: want A2
You know V1 (LVOT PW)
You know V2 (AoV CW)
You can calculate A1:
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Measure LVOT diameter (usually about 2 cm)
Area = pi*r2
Area = 3.14 x ~1
Because the number is squared, biggest area of
error is measurement of LVOT
In our patient:
 A2 (aortic valve area) =
A1 (area LVOT) x V1 (LVOT) /
A2 (AoV velocity)
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LVOT measured 1.8 cm
So A1 = 3.14 x 0.92 = 2.54
V1 = 0.8
V2 = 1.15
A2 = 2.54 x 0.8 / 1.15
A2 = 1.8 (no AS)
There is much more to learn, but start with
the basics to build a foundation.
Then read, learn, and put to use the more
complex cardiac assessments that can be
performed by echo (diastolic dysfunction,
segmental wall motion abnormalities, VTI,
PISA, CO calculation, QP/QS calculation,
speckle, strain, etc, etc, etc)
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 950017202 – MVP with MR
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