Flashcards in Echocardiography Deck (71)
In Echo, how do wavelength and frequency affect resolution?
High frequency, shorter wavelength increase resolution
How does frequency affect tissue penetration?
Higher frequency decreases penetration
What is scattering and why does it happen?
Reflection of US beam in multiple directions due to structures less than 1 wavelength in lateral dimension
What is attenuation?
Absorption of US energy by conversion to heat
Depth of penetration is limited to what amount of wavelengths?
Depth of penetration for:
1. 1 MHz transducer
2. 2.5 MHz transducer
3. 5 MHz transducer
Physics of M Mode
Single crystal rapidly alternating between transmission and receiver modes.
Safety of ultrasound?
No known adverse effects
However theoretical thermal damage and cavitation (creation of small gas filled bodies by the US beam)
What is image quality of 2D echocardiography affected by?
Axial resolution, lateral resolution and elevational resolution
Define axial resolution
Resolution along the length of the US beam
What affects axial resolution?
Define lateral resolution?
resolution perpendicular to the beam
What affects lateral resolution?
Define elevational resolution?
Resolution across the thickness of the tomographic slice
What is the Nyquist Frequency?
Half the Pulse repetition frequency
What happens when velocity exceeds the Nyquist Limit?
What are the factors that affect colour doppler?
What is use of pulse wave doppler
to assess low velocity flows
what is the use of continuous wave Doppler
to assess high velocity flows
What walls of the LV does the A4C view?
Anterolateral and inferoseptal
What walls of the LV does the A2C view?
Anterior and Inferior
What walls of the LV does the A3C view?
Anteroseptal and Inferolateral
What are the echo features of primary TR?
Flail gap 15mm or more
What are the echo features of functional or secondary TR?
Tenting Area >3cm
What is the normal aortic valve area?
What is the peak velocity across the aortic valve which suggests severe stenosis?
What is the peak velocity across the aortic valve which suggests mild stenosis?
What indexed aortic valve area represents severe stenosis?
What are the echo features of mild aortic stenosis?
Valve area >1.5cm2
Transvalvular Velociy 2.0-2.9
Mean Gradient <20mmhg