Alfred E. Cohn

THE RELATION BETWEEN CARDIAC SIZE AND CARDIAC OUTPUT PER MINUTE FOLLOWING THE ADMINISTRATION OF DIGITALIS IN DOGS IN WHICH THE HEART IS ENLARGED

In the preceding paper (Cohn and Stewart, 1928) we have described the effect of digitalis on the cardiac output, cardiac size and cardiac contraction of normal dogs. The cardiac output that obtains in a given dog at a given instant we found is the net result of the working of two distinct, in a sense, opposing actions: first, cardiac size is decreased, and so tends to decrease cardiac output; and second, ventricular contraction is increased, and so tends to increase it. Next, we desired to learn again in dogs whether the same net results are characteristic of the behavior of abnormal, enlarged hearts. Wesoon found that in the absence of heart failure, no significant difference between the two is to be detected; but we are still without information on the situation in which this added defect of heart failure exists. For several years we have been concerned with finding a method which would establish a state in dogs comparable to heart failure in man. One of the methods has consisted in the attempt to bring about this state by rendering the mitral valve insufficient. Wehave for this reason in our possession a number of dogs in which defects of the mitral valve have been made by operation and in which enlarged hearts have in consequence developed. They show no signs however of heart failure. To these dogs we have given digitalis just as to the normal dogs. Estimations of cardiac output, as well as x-ray photographs of cardiac size and of ventricular excursions have been made, just as in the case of the normal dogs.

A study of the rate of water loss from the surfaces of the finger tips and toe tips of normal and senile subjects and patients with arterial hypertension

Abstract The rate of water loss from the tip of the index finger and second toe of normal subjects was very variable. There were variations from one period of fifteen minutes to another, from finger to toe, from right finger to left finger, and from day to day in the same subject. The mean rate of sweating in the toe tips was approximately one-half that in the finger tips, although this ratio could be variable. The rate of sweating varied markedly from person to person under identical conditions of observation. In the patients with arterial hypertension the rate and variations of water loss from the finger and toe tips were about the same as in the normal subjects. This suggests that, in resting persons with hypertension, sympathetic activity is no greater than in normal subjects. In senile subjects the rate of water loss was much less than in the normal subjects and patients with hypertension. Furthermore, the rates from period to period were much less variable. In fact, the senile subjects were outstanding for the constancy with which they lost water. This may be part of the reduced physiologic activity which is known to occur in senile persons.