Efficacy Study of Cardizem in Pulmonary Arterial Hypertension

Inclusion Criteria:

- Adult participants

- Confirmed WHO class I pulmonary arterial hypertension

- Nitric Oxide Non-Responders on right heart catheterization

- Experience dyspnea, NYHA III-IV with poor oxygenation and quality of life despite
standard treatments

- Must be able to swallow medications

Exclusion Criteria:

- Pulmonary hypertension secondary to 1) elevations in pulmonary venous pressures (i.e.
left heart disease), 2) chronic hypoxemic states from lung diseases such as COPD,
sleep-disordered breathing, alveolar hypoventilation disorders, chronic exposure to
high altitude and developmental abnormalities 3) chronic thromboembolic disease, 4)
sarcoidosis, 5) Lymphangiomyomatosis, 5) Pulmonary Langerhans Cell Histiocytosis

- Already on a calcium channel blocker

- Systolic blood pressure less than 90

- Heart rate less than 55

- Pregnant

- Cannot sign informed consent

- Right heart failure

- Pulmonary Veno-occlusive disease