- Determine the overall health and “fitness” of the patient:
- If cardiomyopathy, assess function
- If valvular disease, assess status
- Ascertain if medical optimization has been achieved
- Stratify the patient’s risk, and decide on needed interventions/invasive monitors that can ensure optimal outcome for the patient
- Transthoracic echo (TTE): gold standard for preoperative evaluation
- Transesophageal echo (TEE): if TTE suboptimal (e.g., body habitus, emphysema)
- Two-dimensional echo visualization of anatomic structures
- Color flow Doppler: visualization of blood flow and direction of flow; useful to assess, for example, regurgitant flow from valve (mnemonic BART: blue, away from probe; red, toward)
- Spectral Doppler (continuous/pulse wave) for determination of flow velocities
- Contrast imaging to determine presence of anatomic defects (e.g., PFO)
Figure 6-1. Views Obtained by Transthoracic Echocardiography
Visualization of the heart’s basic tomographic imaging planes by various transducer positions. The long-axis plane (A) can be imaged in the parasternal, suprasternal, and apical positions; the short-axis plane (B) in the parasternal and subcostal positions; and the four-chamber plane (C) in the apical and subcostal positions. Reproduced from Fuster V, Walsh RA, Harrington RA. Hurst’s The Heart. 13th ed. Figure 18-13. Available at: www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.
- Global LV function, cardiac performance
- Regional wall motion abnormalities (RWMA), areas that are likely underperfused or at risk for reversible ischemia
- Valvular dysfunction, type, and severity
- Related pathologies, PFO, masses, pericardial effusion
- Cardiopulmonary pressure calculations, chamber size, and valve areas
- EF (normal around 65%)
- Diastolic function:
- Flow velocities measured across the mitral valve during diastole. Three patterns of diastolic dysfunction are generally recognized based on isovolumetric relaxation time, the ratio of peak early diastolic flow (E) to peak atrial systolic flow (A), and the deceleration time (DT) of E (DTE) (Figure 6-2)
- Valve pathology: mild, moderate, severe (see Chapter 88 on valvular disease):
- MR: decreased forward flow out of aortic valve in systole, with concomitant regurgitant flow into LA during systole, LA enlargement, pulmonary HTN, falsely elevated EF
- MS: decreased forward flow into LV, smaller LV volume, greater percent of LV volume ejection during systole
- AR: regurgitant filling of LV during diastole, increased LV volume (volume overloaded heart)
- AS: increased impedance to flow out of LV, concentric LV hypertrophy, possible decrease in LVEF
- Chamber size:
- Enlargement indicative of either volume overload or pressure overload on heart
- Flow abnormalities and calculation of pressure gradients:
- PA systolic pressure can be estimated if the patient has at least mild TR by measuring the peak velocity (ν) of the regurgitant flow, which is a function of the pressure gradient between RV and RA. A certain RA value (˜CVP) is assumed, typically 5–8 mm Hg unless there is a clinical reason to think it is higher. Modified Bernoulli (continuity) equation: PASP = 4ν2 + RA pressure
- RWMA—visual examination ...
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