
    inability meet enrollment in study population.
  
['pulmonary arterial hypertension']
['inhaled nitric oxide']

        Inclusion Criteria:

          -  The subject or subject's legally authorized representative signs and dates an
             Institutional Review Board (IRB) approved informed consent form prior to the
             initiation of any study-related activities.

          -  The subject has been diagnosed with PAH (WHO Group 1) and is WHO Functional Class I or
             II at Screening.

          -  The subject has documented continuous PGI use for ≥ 1 year from Screening, without a
             significant interruption (i.e., ≤ 2 day interruption) and without a failed complete
             wean attempt.

          -  The subject is a candidate for weaning off parenteral PGI therapy (per Investigator
             judgment and standard of care).

        Exclusion Criteria

          -  The subject has a hypersensitivity or allergy to ingredients of inhaled nitric oxide
             or other clinically significant allergies (clinical significance per Investigator
             judgment).

          -  The subject has a PCWP or left ventricular end diastolic pressure (LVEDP) ≥15 mmHg at
             Baseline.

          -  The subject has participated in an investigational product or device study within the
             30 days prior to Screening.
      