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Visualizes heart in real time with ultrasound; Doppler recordings noninvasively assess hemodynamics and abnormal flow patterns (Table 114-1 and Fig. 114-1). Imaging may be compromised in pts with chronic obstructive lung disease, thick chest wall, or narrow intercostal spaces. Transesophageal echocardiography (TEE) is performed when higher resolution images of cardiac structures is required.
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CHAMBER SIZE AND VENTRICULAR PERFORMANCE
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Assessment of atrial and ventricular dimensions, global and regional systolic wall motion abnormalities (administration of IV echo contrast enhances myocardial border detection when needed), ventricular hypertrophy/infiltration, evaluation for pulmonary hypertension: RV systolic pressure (RVSP) is calculated from maximum velocity of tricuspid regurgitation (TR):
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RVSP = 4 × (TR velocity)2 + RA pressure
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(RA pressure is same as JVP estimated by physical examination.) In absence of RV outflow obstruction, RVSP = pulmonary artery systolic pressure.
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LV diastolic function is assessed by transmitral spectral Doppler and Doppler tissue imaging, which measures velocity of myocardial relaxation (see Fig. 236-8, in HPIM-20).
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VALVULAR ABNORMALITIES
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Thickness, mobility, calcification, and regurgitation of each cardiac valve can be assessed. Severity of valvular stenosis is measured by Doppler (peak pressure gradient = 4 × [peak velocity]2); valve areas are calculated using additional Doppler techniques. Dobutamine echocardiography can clarify degree of aortic stenosis in pts who have poor contractile function or low-flow states. Structural lesions (e.g., flail leaflet, vegetation) resulting in regurgitation may be identified, and color flow and spectral Doppler (Fig. 114-2) estimate severity of regurgitation.
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