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The diagnostic procedures for CAD will be discussed in more depth in the following section on Coronary Heart Disease. Reviewed here is the use of noninvasive testing for noncoronary heart disease.
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ECHOCARDIOGRAPHY & DOPPLER ULTRASOUND IMAGING
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Two-dimensional echocardiography provides information regarding all four chamber sizes, regional and global systolic function, and chamber wall thickness (VIDEO 10–2). Excellent images of valve motion, intracardiac masses, abnormal or absent cardiac structures, and pericardial fluid can all be distinguished. Pulsed wave Doppler provides a semiquantitative or qualitative estimation of the severity of transvalvular gradients, RV systolic pressure (based on a tricuspid regurgitation jet velocity), PA pressure, valvular regurgitation severity, and the presence of intracardiac shunts. The Doppler mitral inflow pattern can help confirm diastolic dysfunction and can help verify a restrictive cardiomyopathic picture or constrictive pericarditis. Color flow Doppler provides a visual pattern of blood flow velocities superimposed over the anatomic two-dimensional echocardiographic image. This allows for the demonstration of turbulence from stenotic or regurgitant valves, and for the visualization of intracardiac defects. Since some regurgitant flow occurs normally, especially when the AV valves close, the presence of minor amounts of regurgitant color flow should not be construed as pathology. Tissue Doppler methods help define the extent of either annular or ventricular wall motion independent of intracardiac flow velocity, and the relationship between the two may prove useful for defining diastolic pressure elevation, identifying abnormalities in ventricular contraction or diastolic relaxation, or optimizing pacemaker therapy. The E wave of the mitral inflow Doppler pattern reflects the rate of blood flow from the LA to LV. The E′ of the tissue Doppler reflects how rapid the LV relaxes. The E/E′ ratio increases if the LA pressure pushing blood into the LV is relatively greater than the rate of relaxation. An E/E′ ratio greater than 15–18, therefore, suggests an elevated LA pressure.
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Echocardiography with contrast agents that fill both heart chambers improves the visualization of wall motion. Other contrast agents have been developed that produce echocardiographic contrast within the myocardium, providing gross myocardial perfusion data. Such perfusion methods have yet to be standardized and have not found wide acceptance.
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The use of Doppler tissue imaging can also provide visual descriptions of wall stress and strain. Measures of longitudinal stress and strain can be displayed visually overlying the image. The value of stress/strain imaging is improving as the techniques have become more standardized; it may be particularly useful in patients where early diastolic dysfunction is present and in defining abnormal myocardium when attempting to separate the athlete's heart (and associated LVH) from a diseased heart (such as HCM). Abnormalities have been observed prior to a fall in the LVEF in patients undergoing chemotherapy. It may also be useful in defining ...