Partial Occlusion of the Aorta with the Metallic Band. Observations on Blood Pressures and Changes in the Arterial Walls

In all except one of the aortic experiments of Dr. Halsted and myself the constricting aluminum band was applied to the abdominal aorta below its inferior mesenteric branch. At the time of our final observations on these animals records were made of the blood pressures in the femoral and carotid arteries. Obviously, in order to draw any conclusions as to the effect of the band on the blood pressure below the site of the constriction, the normal relation between the pressures in these two vessels must be known. In a series of experiments performed by Dr. Dawson on dogs, it was learned that the pulse pressure in the femoral artery is normally about twice as high as in the carotid. The femoral systolic pressure is higher and the diastolic pressure lower than the corresponding pressures in the carotid artery (Fig. 1). After partial occlusion of the aorta the systolic pressure in the femoral is markedly lowered. This lowering of the systolic pressure is due mainly to a fall in the pulse pressure, for the diastolic pressure remains almost stationary, or may be actually increased. In the cases of most marked dilation the femoral pulse pressure was only about one-half the carotid pulse pressure, while the femoral diastolic was actually greater than the carotid diastolic pressure (Fig. 2).