Monitoring the physiology of patients with cardiovascular conditions is useful in preventing or predicting adverse symptoms. However, known predictors of symptoms, such as blood pressure, are difficult to monitor throughout the day. We aim to address this problem in individuals with Postural Orthostatic Tachycardia Syndrome (POTS), which is a condition where the body cannot properly regulate its blood vessels causing lightheadedness, fainting, and spikes in heart rate with little warning. To do so, we will (1) survey individuals with POTS to develop an understanding of what key physiological signals are valuable to monitor, (2) develop an unobtrusive wearable device in a convenient sleeve form-factor, (3) perform a case study with our device on people with POTS to test its efficacy. The primary signal we will collect is pulse transit time (PTT), which is the time for a pulse wave to travel between two points. Prior work has shown PTT is strongly correlated with blood pressure, which is a known predictor of adverse symptoms for POTS. We calculate PTT with two optical sensors consisting of an LED and photodiode at opposite ends of the sleeve. Each sensor allows us to monitor the changes in blood volume and determine when a pulse wave arrives at that point (i.e., PTT). Beyond helping to predict symptoms, we believe our device can help fill knowledge gaps about the physiology behind POTS, as the condition is still not fully understood, and provide physicians with a rich dataset to make medical conditions such as POTS more easily diagnosable.