Mechanism of myocardial edema in dogs with chronic congestive heart failure.

The mechanism of myocardial edema was studied by measuring the changes in the water and electrolyte content of the myocardium of dogs with chronic congestive heart failure and of dogs with other experimental lesions producing chronic ascites. Adrenocortical tissue was also studied for comparison with the changes observed in heart muscle. A marked increase in the water content and in the Na and Cl per gram of fat free tissue solids of the myocardium occurred in congestive heart failure; the K content was unaltered. Assuming that the increment in Cl was distributed extracellularly, this increase in water and electrolytes was extracellular. Chronic passive congestion of the myocardium secondary to elevated right atrial pressure seems to be a major pathogenic factor in myocardial edema formation although hyperaldosteronemia and hypoproteinemia may also play a role.