The diagrams and photographs represent the present state of development of the Aerospace/Loma University School of Medicine cooperative effort to measure the volume of the human heart left ventricle directly from 35 cineoangiograms. A cineoangiogram is obtained by photographing the output of an image amplifier when blood soluble radio opaque contrast media is passed through the heart. The physician passes a catheter through the circulatory system into the vicinity of the heart. At the same time, he raises the voltage on his x-ray, starts the cinecamera, and gives a high speed injection of the contrast media which is heavily loaded with Iodine is used because the very high molecular weight shows up well against the x-rays. Also, the kidneys tolerate the iodine reasonably well when it comes to removing the iodine from the blood stream. Most contemporary procedures are framed at anywhere from 40 to 80 frames per second, although some research efforts go as high as 200 frames per second.