The feasibility group will consist of 10 participants with Group 1 Pulmonary Hypertension (idiopathic, drug induced, or hereditary) to be enrolled in the first phase of the study.

This cohort will consist of 10 participants with Group 1 Pulmonary Hypertension (all types), treatment naïve, to be enrolled in the second phase of the study.

This cohort will consist of 10 participants with Group 1 Pulmonary Hypertension (all types) to be enrolled in the second phase of the study.

This is a medical imaging technique to see inside blood the vessels, especially the arteries around the heart. A catheter with an ultrasound probe at the tip of it will be inserted into a blood vessel and guided to the area that needs to be examined and images of the inside of the vessel will be obtained.

The pulmonary wedge angiography will look at the blood vessels in the lungs to see how blood flows. A catheter is inserted into a vein and it is moved carefully until it reaches the pulmonary artery and temporarily blocks that small vessel.

A contrast dye will be injected through the catheter making the blood vessels visible on x-ray images. Several images are captured with the dye (contrast), called an angiogram.

During the V/Q SPECT, participants will breathe in small amounts of radioactive tracers and will receive an injection of another tracer into your vein that flows with your blood into your lungs. The special camera takes pictures of the tracers to see where air and blood flow in your lungs.