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 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 Modes 1-A mode 2-B mode 3-M mode 4-2D Echogenicity Doppler principles Christian Doppler 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 PRF (or scale) Nyquist limit • Nyquist Limit = Pulse Repetition Frequency / 2 1-PW 2-CW 3-CFM Angle of beam Pressure or pressure gradient? •∆P = P2-P1 = 2 4(V2 – 2 V1 ) Transducers Transducers Manipulation of TEE probe . The ASE/SCA 20 Views for a Comprehensive TEE Exam Left Ventricle function • FS = EDD-ESD EDD • FAC = EDA-ESA EDA • EF = EDV-ESV EDV Left ventricle function Simpson mode M-mode 2D Eye balling TEI index Regional wall motion ME 4 chamber view Trans gastric view Right ventricle Size Contractility Rt Atrium LT atrium LV filling pressure Mitral valve leaflets Mitral valve Stenosis 1-gradient 2-planimetry 3-pressure half time Regurgitation 1-PISA 2-vena contracta 3-jet area 4-Regurgitant fraction 5-Indirect indices Aortic valve Stenosis 1-gradient 2-planimetry Regurgitation 1-PISA 2-jet area 3- vena contracta 4-Indirect indices Tricuspid valve Stenosis Regurgitation Pulmonary valve Stenosis Regurgitation Pulmonary pressure Pulmonary veins Shunts Ascending aorta and LVOT Descending aorta IVC and hepatic veins Recent adavances 3D echo (live and offline) • TDI • Speckle Tracking: non-Doppler, angleindependent 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 books 1-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) Questions??