Echocardiography Flashcards
An understanding of the basic principles of ultrasound imaging.
Echocardiography
It is essential both during data acquisition and for correct interpretation of the ultrasound information.
Doppler echocardiography
A mechanical vibrations that induce alternate refraction and compression of any physical medium through which they pass.
Sound waves
[4] Ultrasound waves
[FVAW]
- Frequency
- Velocity propagation
- Amplitude
- Wavelength
The number of ultrasound waves in a 1-second interval.
[ultrasound waves]
Frequency
Simply means cycles per second.
[ultrasound waves]
Frequency
The speed that a sound wave moves through the body.
[ultrasound waves]
Velocity propagation
Height of the ultrasound wave or “loudness” measured in decibels (dB).
[ultrasound waves]
Amplitude
The distance from peak to peak of an ultrasound wave.
[ultrasound waves]
Wavelength
A characteristic of each tissue defined by tissue density (r) and propagation of velocity (c).
Acoustic impedance
It use a piezoelectric crystal to alternately transmit and receive ultrasound signals.
Transducers
It is generated from the data obtained by electronically “sweeping” the ultrasound beam across the tomographic plane.
2D echocardiographic image
Shown on the video monitor either “scrolling” or “sweeping” across the screen at 50 to 100 mm/s.
M-mode
Recordings allow identification of very rapid intracardiac motion because the sampling rate is about 1800 times per second compared to a 2D frame rate of 30 frames per second.
M-mode
It is based on the change in frequency of the backscattered signal from small moving structures (e.g., red blood cells) intercepted by the ultrasound beam.
Doppler echocardiography
A stationary target, if much smaller than the wavelength, will scatter ultrasound in all directions, with the frequency of the scattered signal being the same as the transmitted frequency when observed from any direction.
Doppler ultrasound
A moving target, however, will backscatter ultrasound to the transducer so that the frequency observed when the target is moving toward the transducer is higher and the frequency observed when the target is moving away from the transducer is lower than the original transmitted frequency.
Doppler ultrasound
CW Doppler uses two ultrasound crystals;
Continuously transmits and continuously receives the ultrasound signal
It allows sampling of blood flow velocities from a specific intracardiac depth. A pulse of ultrasound is transmitted, and then, after a time interval determined by the depth of interest, the transducer briefly “samples” the backscattered signals.
Pulsed doppler echocardiography
Used to generate color Doppler flow images and tissue Doppler recordings.
Pulse doppler
It uses the pulsed Doppler principle to generate a 2D image or “map” of blood flow velocity superimposed on the 2D real-time image.
Color Doppler
It is the most useful for visualization of spatial flow patterns; for this purpose, examiner preference determines the most appropriate color scale.
Color Doppler
It provides a panoramic view of the abdomen and pelvis and is noninvasive, whereas TVU provides a more limited pelvic view and requires insertion of a probe into the vagina.
Transabdominal ultrasound
Provides a better view of the uterus and adnexa during early pregnancy.
Transvaginal ultrasound
It is one of the most commonly performed
cardiac investigations.
Transthoracic echocardiography
An examination performed by a physician or by a trained cardiac sonographer under the supervision of a qualified physician.
Echocardiographic examination
The term in echocardiography that refers to the bedside use of small, lightweight ultrasound systems.
point-of-care
It may be a useful tool in patient triage, in screening populations, and in medical education.
Point-of-care
