Right ventricular (RV) failure is the predominant cause of death in pulmonary arterial hypertension (PAH). No RV-specific therapies are available, in part because the underlying mechanisms of RV dysfunction are poorly understood. Given the heart's preference for fatty acids (FA) as an energy source, a deeper understanding of FA metabolism may shed light on RV adaptation to elevated afterload in PAH. The purpose of this study is to test the hypothesis that defects in fatty acid metabolism are common in PAH and contribute to RV failure. The investigators will measure peripheral and transcardiac lipid and glucose metabolites in PAH patients in comparison with patients with pulmonary venous hypertension and no evidence of pulmonary hypertension. The investigators will also correlate metabolites with concurrent measurement of right ventricular function.

Inclusion Criteria:

• ≥ 18 years old
• Scheduled to undergo cardiac catheterization (right ± left heart catheterization) and/or electrophysiology study in the VHVI cardiac catheterization laboratory (CCL)/electrophysiology laboratory (EP lab)
• Hemoglobin value ≥ 10 g/dL or hematocrit of ≥ 30% (measured on clinically-indicated blood draw within 30 days or a point-of-care measurement in CCL/EP Laboratory if clinically-indicated value is not available)

Exclusion Criteria:

• Any individual that is anemic and has a hemoglobin value < 10 g/dL and hematocrit of < 30% will be excluded from the study.

• If a physician performing the procedure believes that performing the extra steps and /or acquiring the additional blood samples will delay or otherwise compromise participants' care, he/she can abandon acquisition of those data at his/her discretion.

• Contraindication to cardiac MRI (applies only to patients undergoing CMR as part of this protocol).

  • Implanted ferromagnetic material
  • Glomerular filtration rate < 60mL/min (measured on clinically-indicated blood draw within 30 days of CMR or a point-of-care measurement in the CMR Laboratory if clinically-indicated GFR is not available)

PAH