RESUMO
Dilated cardiomyopathy is characterized by systolic dysfunction and cardiac enlargement of unknown origin. Various Doppler modalities are useful to detect and quantitate atrioventricular regurgitation, which is common and contributes to clinical symptoms. Pulsed Doppler assessment of mitral and tricuspid inflow velocities shows a spectrum of findings indicative of abnormal diastolic function and hemodynamic status. When mitral regurgitation is more than moderate and heart failure is severe, the ratio between early inflow E wave to atrial inflow A wave peak velocities is increased. Mitral deceleration time may be short. When mitral regurgitation is trivial and left atrial pressure is not increased, abnormal relaxation may be detected as a low E:A ratio. Mitral deceleration time and isovolumic relaxation time are prolonged. In restrictive cardiomyopathy, there is an abrupt limitation in early ventricular filling due to abnormal compliance of endocardial or endomyocardial origin. Mitral and tricuspid inflow velocities show normal to increased early peak velocity, rapid deceleration time, low peak atrial velocity, and an increased E:A ratio. Differentiation between restriction and constriction might be possible by the demonstration in pericardial constriction of inspiratory decreases in mitral early inflow peak velocities and in prolongation of isovolumic relaxation time, with reciprocal changes on tricuspid inflow velocity profiles. In constriction, these respiratory variations are caused by the ventricular limitation to accommodate changes in venous return due to the pericardial shell. Doppler abnormalities and two-dimensional echocardiographic assessment of ventricular and atrial size and ejection fraction provide the practicing physician with valuable diagnostic information.
