Endo-PAT2000 is a simple, non-invasive, inexpensive, office-based device used for diagnosis of endothelial function, which is the earliest clinically detectable stage of cardiovascular disease. The system uses a biosensor mounted on the patient's finger to measure small changes in blood vessels relying on Itamar's peripheral arterial tone (PAT) signal technology. It measures endothelium-dependent blood flow-mediated dilation (FMD) in one arm, while the contralateral arm controls systemic changes in vascular tone. It can provide results to clinicians in about 15 minutes.