The PI closed this study and went to another institution.

Subjects in this study have been diagnosed with pulmonary hypertension (PH) and their doctors have referred them for a right heart catheterization (RHC). Heart catheterization involves inserting an IV (a needle with a small tube) into a vein in the neck. A long, narrow tube, called a catheter, is guided through the IV into the blood vessel and guided to the heart (sometimes this procedure can be done through a vein in the groin instead). Once the catheter is in place, small instruments can be inserted into the catheter to measure the pressures in different areas of the heart. These measurements can help the doctor diagnose possible problems with the heart functioning.

The purpose of this study is to evaluate the measurements provided by a device, called Noninvasive Cardiac Output Monitoring (NICOM). The NICOM device is non-invasive which means the investigators do not have to go inside the body to obtain the heart pressure measurements. While the device has been approved for use in any patient, it remains possible that patients with PH will have differences in the way the device calculates measurements. In this study, the investigators will compare the in-the-body (right heart catheterization) measurements to the non-invasive, outside-body measurements provided by the NICOM device to evaluate any differences.

The NICOM device is approved by the US Food and Drug Administration (FDA) to measure heart pressures. This device is usually used when a patient can't undergo a right heart catheterization. In this study, the investigators are using the device to gather heart pressure measurements for research during the right heart catheterization procedure that is scheduled as part of the patients' normal, routine care. The research data is being used to devise better, less invasive ways to assess disease severity, track disease progression and evaluate response to therapy. The NICOM device is made by Cheetah Medical.

Inclusion Criteria:

• 18 years old and up
• have Pulmonary Hypertension (PH)
• Scheduled for cardiac catheterization with right heart catheterization and acute vasodilator testing as part of their evaluation of PH

Exclusion Criteria:

• unable or unwilling to give informed consent

We will enroll 100 consecutive patients referred to the Pulmonary Hypertension Center and scheduled for cardiac catheterization with right heart catheterization and acute vasodilator testing as part of their evaluation of PH.