Reduced aortic stiffness is a powerful way to predict the outcome of cardiovascular (CV) disease. There are several non invasive methods for its estimation, most of which are based on the measurement of speed of the arterial pulse wave. (The stiffer the artery, the faster the pulse wave travels.) They rely on detecting the arterial pulse with 2 sensors placed on the skin a known distance apart and measuring the time for the pulse to travel between them. However all current methods require skilled operators and are of limited accuracy. Thus, there is a need for an easy to use and reliable device to measure pulse speed. The aim of this project is to develop a non contact device to detect the aortic pulse as it moves into the small arteries following the ribs, using the principle of thermal imaging, by means of a high sensitivity infra red camera, directed towards the subjects back. The investigators plan to validate the device and conduct a small feasibility study in patients undergoing elective angiography, by simultaneously measuring pulse speed using established methods. These are Doppler ultrasound (non-invasive) and direct intra-arterial measurement (the gold standard).