Visualizes heart in real time with ultrasound; Doppler recordings noninvasively assess hemodynamics and abnormal flow patterns (Table 112-1 and Fig. 112-1). Imaging may be compromised in pts with chronic obstructive lung disease, thick chest wall, or narrow intercostal spaces.
TABLE 112-1CLINICAL USES OF ECHOCARDIOGRAPHY ||Download (.pdf) TABLE 112-1CLINICAL USES OF ECHOCARDIOGRAPHY
|2-D Echo ||Transesophageal Echocardiography |
|Cardiac chambers: size, hypertrophy, wall motion abnormalities ||Superior to 2-D echo to identify: Infective endocarditis |
|Valves: morphology and motion || Cardiac source of embolism |
|Pericardium: effusion, tamponade || Prosthetic valve dysfunction |
|Aorta: aneurysm, dissection || Aortic dissection |
|Assess intracardiac masses || |
|Doppler Echocardiography ||Stress Echocardiography |
|Valvular stenosis and regurgitation ||Assess myocardial ischemia and viability |
|Intracardiac shunts || |
|Diastolic filling/dysfunction || |
|Approximate intracardiac pressures || |
Two-dimensional echocardiographic still-frame images of a normal heart. Upper: Parasternal long axis view during systole and diastole (left) and systole (right). During systole, there is thickening of the myocardium and reduction in the size of the left ventricle (LV). The valve leaflets are thin and open widely. Lower: Parasternal short axis view during diastole (left) and systole (right) demonstrating a decrease in the left ventricular cavity size during systole as well as an increase in wall thickness. Ao, aorta. (Reproduced from RJ Myerburg: HPIM-12.)
Chamber Size and Ventricular Performance
Assessment of atrial and ventricular dimensions, global and regional systolic wall motion abnormalities, ventricular hypertrophy/infiltration, evaluation for pulmonary hypertension: RV systolic pressure (RVSP) is calculated from maximum velocity of tricuspid regurgitation (TR):
(RA pressure is same as JVP estimated by physical examination.) In absence of RV outflow obstruction, RVSP = pulmonary artery systolic pressure.
LV diastolic function is assessed by transmitral Doppler (see Fig. 270e-8, in HPIM-19) and Doppler tissue imaging, which measures velocity of myocardial relaxation.
Thickness, mobility, calcification, and regurgitation of each cardiac valve can be assessed. Severity of valvular stenosis is calculated by Doppler [peak gradient = 4 × (peak velocity)2]. Structural lesions (e.g., flail leaflet, vegetation) resulting in regurgitation may be identified, and Doppler (Fig. 112-2) estimates severity of regurgitation.
Schematic presentation of normal Doppler flow across the aortic (A) and mitral (B) valves. Abnormal continuous wave Doppler profiles: C. Aortic stenosis (AS) [peak transaortic gradient = 4 × Vmax2 = 4 ×(3.8)2 = 58 mmHg] and regurgitation (AR). D. Mitral stenosis (MS) and regurgitation (MR).
Echo is noninvasive modality of choice to rapidly identify pericardial effusion and assess its hemodynamic significance; ...