Retrograde transmission of left atrial pressure pulses across the pulmonary capillary bed in dogs.

Retrograde transmission of left atrial pressure across the pulmonary capillary bed was studied in dogs employing graduated left atrial pressures. Left atrial pressures below a level of 30 to 35 mm. Hg were transmitted across the pulmonary capillary bed as mean pressures; in the case of higher left atrial pressures the cyclic changes were transmitted with a certain amount of damping. Pressures were recorded both from the tip of a catheter wedged into a peripheral pulmonary artery and from the occluded main artery of one lung. Pressures recorded from the occluded main artery of one lung are a reflection of cyclic left atrial pressure variations and are less damped than those recorded from a wedged catheter tip.