Interpretation of aortic root angiography in dogs and in humans

It has been suggested that aortic root angiography shows the opening of the aortic valve in humans to be triangular. We investigated whether aortic root angiography does indeed permit determination of area and configuration of the aortic valve. Various angiographic views of the aortic valve were recorded in dogs and humans and were compared with similar views obtained photographically of aortic valve models designed to show circular and a triangular orifice. It was observed that the aortic root angiograms were the projection of the entire aortic valve flow conduit in systole. The orifice seen in any angiogram was truly the inside boundary of the dye, composed of the free edge and the line of attachment of the leaflets. This orifice did not represent the true orifice of the valve, and its configuration depended upon the angle of the X-ray and the orientation of the valve. The comparison also revealed that, in dogs and in humans, the opening of the aortic valve is circular, a fact further shown to correlate better with the clinical observations.