Echocardiography

1. ECHOCARDIOGRAPHY
BASICS KARTHIK K S

2. • ECHOCARDIOGRAPHY
* Echocardiography is the use of ultrasound waves to study the structure and
function of heart and its great vessels.
* The visual image formed by using the technique is called electrocardiogram.
• ULTRASOUND
* Sound spectrum > 20kHz
* It can be directed as a beam and focused.
* As it is passed through a medium it obeys the laws of reflection and laws of
refraction.

3. • PROPERTIES OF ULTRASOUND
a) Wave length
* Distance between successive crests of a wave.
λ=v/f λ- wavelength f – frequency of a
wave
v – velocity of a wave
* Image resolution - it decreases with increase in wavelength.
* Penetration - it increases with increasing wavelength.

4. b) Frequency
The number of ultrasound waves in the unit time.
Unit – Hz (hertz)
c) Velocity
It is the speed that a sound wave moves.
* velocity of propagation of ultrasound waves in the soft tissues including myocardium,
valves,
blood vessels and blood is 1540 m/s.

5. d) Amplitude
It isthe height of the ultrasound waves.
* Measured in decibels (dB)

6. TRANSDUCER
→Generate and to receive ultrasound waves.
→Constituents :
a)Piezoelectric element
b)Backing layer
c)2 electrodes
d)Matching layer

8. PIEZOELECTRIC CRYSTALS
→Piezoelectric crystals are capable of the piezoelectric effect, which is the ability to
generate electric charge when subjected to pressure.
→ Piezoelectric effect converts mechanical energy, due to crystal deformation into
electrical energy & thus transducers recieves ultrasound waves.
Piezoelectric Crystals Eg: * Quartz
* Titanate ceramics

9. BACKING MATERIAL
→ plays an important role in determining the characteristics of the wave that is
produced.
MATCHING LAYER
→They are applied to provide acoustic impedance matching between the
piezoelectric elements and the body.
TWO ELECTRODES
→Electodes transmit current to the crystals and record the voltage generated by
returning signals.

10. TYPES OF PROBES
a) Linear probes :
→ For imaging superficial structures
→Vascular probes
b) Curve linear probes :
→ Lower frequency
→ Transabdominal imaging
c) Array probes :
→ Cardiac probes
→ Phased array of piezoelectric crystals

11. d) Endocavitary probes :
→ High frequency
→ Transvaginal and transrectal probes
e) TEE probes

13. OPTIMIZATION OF ECHO IMAGES
*Frequency
The typical range of frequencies used in adult echocardiography is 2 to 5 MHz.
*Power
Amplitude of the sending beam
Normal power =0dB
With increasing power Thermal index (TI) and Mechanical index(MI) increases and should
set up power at a MI <1.9 and TI<2.
*Frame Rate
Frame rate is influenced by several settings (imaging frequency, depth, sector width). It is
also possible to directly adjust frame rate. Frame rate determines the temporal resolution.

14. *Depth
-The depth determines how “deeply” into the body one wishes to image
-Depth influences spatial resolution, pulse repetition frequency (PRF) and frame
rate.
*Focus
the ultrasound beam has a focal zone.
*Zoom
Zoom permits the magnification of a selected area of interest.

15. *Gain
Overall gain adjusts the amplitude of the received signals over the total length of
the ultrasound beam.
When there is increase in gain, the received signals are amplified (not the sent
signal). The image becomes brighter.
Excessive increase in gain will add “noise” to the image.
If the gain is too low, tissue with a low reflector intensity will not be seen
*Time Gain Compensation
Allows differential adjustments along the length of the ultrasound beam to
compensate for the effect of attenuation