Not just left and right arms, but also left and right ankles. The Ankle Brachial Index (ABI) is the systolic pressure at the ankle, divided by the systolic pressure at the arm. It has been shown to be a specific and sensitive metric for the diagnosis of Peripheral Arterial Disease (PAD). Beyond this is Peripheral Vascular Doppler Ultrasound. I don't have any specific links, but you can find some documentation on nih.gov. I find it most effective to utilize google and put in "site:nih.gov search topic"