Figure 4
Right Heart Hemodynamics. Right heart hemodynamic waveforms for the control and 1000-ml effusion cases during apnea at mean pleural pressure (-3 mmHg). The systolic and diastolic intervals are indicated, with relatively shorter intervals in the 1000-ml effusion case due to higher heart rate. The left column shows normal pericardial pressure and right atrial pressure (Panel A), right atrial volume (Panel C), right ventricular volume (Panel E), tricuspid flow (Panel G), and inferior vena caval flow (Panel I), respectively. With 1000-ml effusion (right column), the right atrial pressure waveform is elevated to equalize pericardial pressure (Panel B) and the y-descent in particular is reduced (Panel B). Pericardial pressure displays two dips in pressure, corresponding to ventricular ejection (labeled systolic dip) and atrial ejection (labeled diastolic dip). Systolic atrial filling is slowed as shown by the gradual increase in right atrial volume (Panel D) and slower vena caval flow (Panel J). The reduced diastolic venous return (Panel J) is associated with a lower right atrial volume at end diastole (Panel D). Right ventricular volume variation exhibits reduction due to both filling and stroke output changes, with volume labels (ml) shown (Panels E-F). The E-wave is reduced and the A-wave is more prominent (Panel H). The reversed component of vena caval flow (AR) is no longer present (Panel J). The diastolic-to-systolic (D/S) venous volume ratio is shown below each case, which decreases with tamponade. See text for details.