Accuracy of Smartwatches in Measuring Oxygen Levels in Patients With Pulmonary Hypertension: A Pilot Study

The goal of this study is to learn how accurate smartwatches are at measuring oxygen levels in patients with a condition called pulmonary hypertension. The main questions it aims to answer are: * How accurate the smartwatches are at measuring oxygen levels when the patient is sitting at rest * How accurate are smartwatches at measuring oxygen levels after exercise * How accurate are smartwatches at measuring oxygen levels after breathing a lower level of oxygen through a mask. Researchers will compare oxygen levels measured through a smartwatch with those checked through a finger probe oxygen monitor and also from a blood sample checked from the artery in the wrist to see if smartwatch oxygen measurements are similar. Participants will: -Attend the hospital once, just for a few hours to collect all the required data.