Eisenmenger Quality Enhancement Research Initiative (QuERI) is a multi-center, observational, US-based longitudinal program, with enrollment of consecutive Eisenmenger patients who meet enrollment. Patient data will be collected prospectively for three years. Individual physician feedback will be provided on data collected with the purpose of improving the management of patients - quality enhancement research initiative (QuERI) process.

Approximately 200 male and female adult patients with a history of Eisenmenger will be recruited from approximately 50 cardiology practices over a period of 18 months and will be followed up every six months for the period of three years. Consecutive patients in each practice meeting inclusion and exclusion criteria should be considered for the study. Participating sites will be asked to maintain a screening log to identify which inclusion or exclusion criteria was not met thus excluding them from the study.

Inclusion Criteria:

• Male and female patients
• Diagnosis of Eisenmenger syndrome based on right heart catheterization data
• Right to Left intra-cardiac shunting
• PAH
• Need for comprehensive management according to guidelines and peer-reviewed evidence
• Ability and desire to execute the consent for follow up

Exclusion Criteria:

• Poor mental function, drug, or substance (e.g.,alcohol) abuse, or unstable psychiatric illness, which, in the opinion of the investigator, may interfere with optimal participation in the study
• Prior inclusion in this program

200 adult patients with Eisenmenger Syndrome recruited from approximately 50 US cardiology practices.