Prior to performing the test, the patient’s blood pressure will be measured because these values are needed to properly perform the test. An uninflated blood pressure cuff will then be placed on the non-dominant arm for use later in the test. Next, an Endopat probe, which is a plastic cylinder into which the finger is inserted, will be placed on the index finger of each hand and its tubing will be secured with tape. This device will measure arterial tone throughout the test. The patient will then be instructed to remain still for 5 minutes while a baseline recording is taken. Following the baseline measurements, the blood pressure cuff on the non-dominant arm will be inflated to a pressure greater than the systolic blood pressure in order to stop blood flow to that arm. The cuff will remain inflated for 5 minutes. Finally, the cuff will be deflated and data will be recorded for 5 additional minutes.