Further experimental evidence that pulmonary capillary pressures do not reflect cyclic changes in left atrial pressure (mitral lesions and pulmonary embolism).

Wedged catheter pressures (PC) were compared with those in the aorta, left atrium, and pulmonary artery before and after production of mitral stenosis, insufficiency, and pulmonary embolism. In general it was found that "PC" pressures follow closely changes in left atrial pressures even when pulmonary artery pressure changes in an opposite direction (for example, pulmonary embolism). However, properly recorded "PC" pressure pulses did not display the large cyclic pressure variations recorded from the left atrium during mitral stenosis and insufficiency. It is concluded that pressures recorded through a properly wedged catheter represent the constant pulmonary capillary pressure but do not reflect cyclic pressure variations in the left atrium.