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Basics of Echocardiography. Mostafa Eladawy MD,AFSA. Ultrasound principles. Penetration depth and resolution. Factors affecting ultrasound transmission: cycle length: (wavelength λ [mm]) frequency: (frequency f [Hz]) Speed: (propagation velocity c [m/s]) in the respective medium
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Basics ofEchocardiography • Mostafa Eladawy MD,AFSA
Penetration depth and resolution Factors affecting ultrasound transmission: cycle length: (wavelength λ [mm]) frequency: (frequency f [Hz]) Speed: (propagation velocity c [m/s]) in the respective medium The relationship of these parameters is described by the wave equation: c = λ × f λ = c / f longer wavelengths penetrate further than shorter wavelengths Image resolution cannot be greater than one wavelength the higher the ultrasound frequency, the better the image resolution
Types of resolution • Axial resolution • Lateral resolution • Elevational resolution
The difference between the emitted frequency and the received frequency is called: Doppler shift (fd ) • Blood flow V = fd × c/2 × f0 × cos α • For practical application in Doppler echocardiography: the emitted frequency (f0) is known and the velocity of sound (c/2) is constant at 1540 m/s. Therefore, the velocity causing the Doppler shift can be calculated by: V = fd × cos α
Nyquist limit • Nyquist Limit = Pulse Repetition Frequency / 2
Left Ventricle function • FS = EDD-ESD EDD • FAC = EDA-ESA EDA • EF = EDV-ESV EDV
Left ventricle functionSimpson modeM-mode2D Eye ballingTEI index
Mitral valveStenosis1-gradient 2-planimetry3-pressure half time
Regurgitation1-PISA2-vena contracta3-jet area4-Regurgitant fraction5-Indirect indices
Regurgitation1-PISA2-jet area3- vena contracta4-Indirect indices
TDI • Speckle Tracking: non-Doppler, angle-independent quantification of myocardial deformation, by tracking the displacement of the speckles during the cardiac cycle, strain and the strain rate can be measured offline.
Recommended books1-Practical approach to transesophageal echocardiography(Perrino)2-Core topics in echocardiography (Rob Fenneck)3-Atlas of multiplane transesophageal echocardiography (Martin Dunitz)4-transesophageal echocardiography in anesthesia and intensive care (BMJ)5-Pocket atlas of echocardiography (Thieme)5-Essential echocardiography (Humana press)