Right Duct Lymph Flow in Experimental Heart Failure Following Acute Elevation of Left Atrial Pressure

We measured the pulmonary lymph flow in dogs with mild congestive failure before and after acute elevation of the left atrial pressure to 40 cm of water. The creation of an aorticocaval fistula and the administration of desoxycorti-costerone trimethylacetate and a salt enriched diet in 6 dogs produced mild pulmonary edema and partial expansion of the pulmonary lymphatics 10 to 12 days postoperatively. Elevation of the left atrial pressure to 40 cm of water under pentobarbital anesthesia led to an immediate increase in right duct flow in the "mild failure" dogs, in contrast to a delayed flow in normal dogs. The average peak flows in the 10- to 12-day dogs after increasing the left atrial pressure were higher than the peak flows observed in normal dogs. In addition, the mild failure dogs survived twice as long as normal dogs after acute elevation of the left atrial pressure. These results suggest that an animal with an expanded pulmonary lymph system is better able to withstand the stress of acute elevation of left atrial pressure than a normal animal. The pulmonary lymph system may serve as an important compensatory mechanism in the prevention of fulminating pulmonary edema.