Although methods exist based on flow across each of the valves, those that relate to either the aortic or pulmonary outflow tracks are considered optimal since the orifice through which flow occurs is relatively constant in size and is easily modeled geometrically.
Echocardiography also provides simple methods for calculating pulmonary artery systolic and diastolic pressure based on the tricuspid and pulmonic regurgitant jets respectively. These methods are widely used clinically and have been extensively validated. Recently, a number of methods have been reported for determining left ventricular filling pressures.1
These methods include approaches that are based on mitral and pulmonary venous inflow spectra, Doppler tissue imaging of the mitral annulus, and color Doppler M-mode of mitral inflow.
A number of parameters that can be determined echocardiographically have been identified as negative prognostic factors in patients with heart failure and systolic dysfunction. Reduced left ventricular ejection fraction (less than 25%) is a strong negative prognostic factor and impaired right ventricular systolic performance is also an important independent predictor of increased mortality and morbidity.
Echocardiographic methods of assessing right ventricular systolic performance are not as well developed as those for the left ventricle, due in part to the complex geometry of the right ventricle.
Two-dimensional echocardiographic techniques include the tricuspid annular plane excursion, fractional area change, and systolic velocities defined by Doppler tissue imaging. Recently developed realtime 3-D echocardiographic techniques promise to be extremely valuable tools for assessing the right heart.
The myocardial performance index as applied to both right and left ventricular function has also been identified as being prognostically important, as has the presence of functional mitral regurgitation and the response of the left ventricle to dobutamine stress. It is notable that patients who do not demonstrate myocardial contractile reserve with dobutamine infusion do less well than those in whom recruitable myocardial systolic performance is demonstrable.
- A full discussion of these techniques is beyond the scope of this article and the reader is referred to an excellent review on the subject by Nagueh, et al., in the American College of Cardiology Current Journal Review (Jan/Feb 2002).