1. Introduction to Echocardiography
Courtesy of Dr. Susan Yeon, M.D., J.D.
Edited by Dr. Joyce Meng M.D.

2. Ultrasound Imaging US beam transmitted into chest with
reflection, scattering, refraction, and attenuation
Signal is reflected off interfaces
tissue planes
blood/tissue borders
Attenuation of transmitted beam reduces returning signal to 1/10,000 of original power

3. Production of ultrasound
Piezoelectric crystals
Transmitter: Emit ultrasound when stimulated by electric current
Receiver: Produce electric current when stimulated by returning ultrasound signal
Depth information is determined by the time delay of the returned signal
Transducer sends out pulses of ultrasound and “listens” for returning signal

5. Two-dimensional imaging
Multiple pulses sent out along adjacent scan lines
Sector formed by multiple scan lines
Process repeated multiple times for “live” imaging
Speed of US in tissue and rapid signal processing allow real time imaging
(30 frames/sec)

6. Johann Christian Doppler
Doppler effect
A sound wave reflected from a moving object changes its frequency proportional to the velocity of the object

7. Doppler Effect Doppler effect used to calculate
velocity of galaxies as well as velocity of trains
or red blood cells relative to observer

8. Doppler Pulse of ultrasound directed at moving object (blood)
Frequency shift of returning signal indicates direction and velocity of object
Pulsed wave Doppler
Determine velocity in a small area called sample volume
Cannot resolve velocities >1m/sec
Continuous wave Doppler
Cannot resolve location of velocity along line
Can resolve any physiologic velocity
Color Doppler
Sample a large area and inform us of
Direction of jet
Extent of jet
Limited temporal resolution

9. Color vs Pulse Wave Doppler
MR velocity aliases since velocity> 1 m/sec
-Mild to moderate MR

10. Continuous Wave Doppler
Toward
Transducer
Time
Away from
Transducer
Velocity cm/sec

11. Some Uses of Transthoracic Echocardiography
Evaluation of ventricular structure and systolic and diastolic function
Congestive heart failure
Coronary artery disease
Cardiomyopathies
Valvular abnormalities
Prolapse
Regurgitation
Stenosis
Masses
Endocarditis
Thrombus
Benign or malignant tumors
Pericardial disease
Pulmonary hypertension
Congenital abnormalities
Atrial or ventricular septal defects
Patent foramen ovale
Transposition of the great vessels

12. The Normal Echocardiogram

13. Standard Views Parasternal Long Axis Parasternal Short Axis
Apical 4 Chamber
Apical 2 Chamber
Apical 3 Chamber
Subcostal Long Axis

14. Standard Echocardiographic Views

28. Valvular regurgitation
Color doppler showing tricuspid and mitral regurgitation
Looking at the size, width, color (therefore the velocity) and the location of the jet is one way of determining the severity of the regurgitation.

29. Bernoulli Equation pv2
Daniel Bernoulli
Change in pressure across a small orifice is proportional to the square of the velocity of the fluid flowing through the orifice
Simplified Equation
pv2

30. Application of Bernoulli
Measurement of PA pressure
Velocity of tricuspid regurgitation jet is proportional to RV systolic pressure
Can estimate RA pressure
PA=RA+4(peak TR velocity)2
VERY IMPORTANT- off angle measurements underestimates velocity. RA RV TR

31. Continuity Equation A1V1=A2V2 Measure stenotic valve area
Usually applied to aortic stenosis
Assumptions
Fluid is incompressible
Flow = mean velocity * cross sectional area
Flow by any cross section in the pipe is the same F1=F2
A1V1=A2V2

32. Aortic Stenosis Calculations
Pulsed Wave LVOT
Continuous Wave AV
Again, off-axis measurements will introduce error!!

33. Aortic Stenosis Calculations

34. Transesophageal Echocardiogram
Ultrasound probe in the esophagus
Offers superior views of the posterior structures of the heart (LA, pulm veins, mitral valve)
Decreased distance between the transducer and the structures
No intervening lung, bones…etc

35. Disdvantages of TTE vs TEE
More invasive
Maybe less optimal for anterior structures
Transducer position restricted by the esophagus
Cannot obtain standard anatomic measurements (i.e. forshortened)
Cannot always align the ultrasound beam parallel to the flow of interest.
TTE
Image quality often suboptimal due to intervening tissue and long distance between the transducer and the heart (especially for posterior structures)

36. Complications of TEE Fairly safe procedure:
Risk of esophageal intubation includes dental trauma, esophageal trauma/perforation, bleeding, aspiration, dislodgement of NG/ET tube…etc.
Risk of conscious sedation including hypotension, respiration depression…etc.
Complication serious enough to interrupt the procedure in <1%, mortality rate of fewer than 1 in 10,000 patients.
Contraindicated mostly due to local esophageal problems:
Esophageal stricture or malignancy
Recent esophageal ulcer or hemorrhage
Zenker’s diverticulum.
Needs screening endoscpy and/or barium swallow prior to TEE if there is a history of odynophagia and dysphagia

37. Stress Echocardiography
Can be done after exercise testing or dobutamine infusion
Image acquired shortly after exercise and compared with baseline to detect newly induced wall motion abnormalities.
Have to acquire the image quickly enough
Overall accuracy- 76% sensitive, 88% specific
Compare to SPECT MPI, about 10% less sensitive and 10% more specific
Stress echo is not a full echo! Detail assessment of valvular function, pulmonary artery pressure…etc. are not routinely done.

38. Echo can also evaluate masses and vegetations