Observational Study of Patients Undergoing Diagnostic Right Heart Catheterization

This is an observational study in which researchers measure heart function using a thin tube inserted into the right side of the heart (a right heart catheterization, or RHC). The study aims to better understand pressure and blood flow measurements in the heart across a range of cardiac conditions. No experimental treatment is being given — participants are simply having a procedure that was already scheduled. **You may be eligible if...** - You are 18 years or older - You are already scheduled to undergo a right heart catheterization procedure (with or without a left heart procedure done at the same time) - You are willing to sign informed consent **You may NOT be eligible if...** - You are pregnant, breastfeeding, or plan to become pregnant during the study - You are only scheduled for a left heart catheterization (not a right heart procedure) Talk to your doctor to see if this trial is right for you.