Fig. 1

Comparison of pressure in the ascending aorta (AP, in red) and right ventricle (RVP, in blue) along with the pressure gradient between them (AP-RVP, in black) driving coronary perfusion. Under normal conditions (left panel), AP > RVP at all times facilitates RV perfusion in both systole and diastole. In contrast, in the setting of marked pulmonary hypertension (PH) (right panel), RVP can exceed AP during the systolic portion of the cardiac cycle thus eliminating the positive pressure gradient during systole and limiting perfusion to the diastolic interval. Data were obtained during an experimental study of progressive pulmonary embolization under a protocol approved by the institutional animal care and use committee. The figure is reproduced with permission from the PeriOperative Quality Initiative (POQI)