Volume and Pressure Dependence of Left and Right Ventricular Filling in Dilated Cardiomyopathy

In heart failure with elevated ventricular diastolic pressure ventricular filling is predominant in early diastole. This study tested whether in dilated cardiomyopathy the right ventricle (RV) shares with the left ventricle (LV) a redistribution of flow to early diastole; Doppler filling indexes of both ventricles are influenced by changes in diastolic pressures and volumes. In 12 patients with dilated cardiomyopathy we recorded mitral and tricuspid flows, M-mode and cross-sectional echocardiograms and right and left hemodynamics before and after restraint of venous return with inferior vena cava balloon obstruction (IVCBO). Through IVCBO we reduced cardiac output, right atrial pressure, pulmonary wedge pressure and did not affect mean aortic pressure and heart rate; we also obtained a significant reduction of LV and RV volumes, while LV systolic function was steady. Impedance to venous return lowered the early- late ventricular filling ratio in both sides of the heart, peak velocities of early mitral and tricuspid flow being reduced and late velocities remaining steady. Redistribution of filling to late diastole in both ventricles following IVCBO suggests that a pseudonormalization of Doppler indexes was present at baseline and was mediated through the elevated diastolic pressures and the excessive ventricular volumes. An influence of pericardial restraint seems reasonably involved in the pseudonormal filling pattern of dilated cardiomyopathy.