[Timing of inflow to the atrium after ventricular contraction and relaxation: effect of atrial wall stiffness].

A stiff atrium is sensitive to even a small change in its volume, causing a rapid change in the caval vein flow. We hypothesized that the onset of caval vein flow may follow immediately after the onset of a ventricular event in a patient with a stiff atrium. The timing of inflow into the right ventricle and into the atrium were examined by Doppler echocardiography in 20 healthy subjects, 12 patients with constrictive pericarditis, and 10 patients with cardiac tamponade. The onset of diastolic flow in the superior vena cave followed 17 +/- 14 msec after the onset of early diastolic filling flow into the right ventricle in constrictive pericarditis patients, which was significantly shorter than 107 +/- 45 msec in the healthy subjects. The onset of systolic flow occurred 178 +/- 46 msec after the peak of the R wave of the electrocardiogram in cardiac tamponade patients, which was significantly longer than 129 +/- 17 msec in healthy subjects. This time was slightly shorter in constrictive pericarditis (103 +/- 21 msec). We conclude that a short time lag from the onset of a ventricular event to the onset of caval flow indications that the right atrium is stiff.