The objective of this study is to assess the safety, performance and initial effectiveness of the TIVUS™ System when used for pulmonary artery denervation through subjective and objective change in clinical parameters and haemodynamic evaluation. This is a prospective, multi-center, non-randomized, open-label clinical trail. The study will be conducted in up to 4 centers and will recruit up to 15 patients diagnosed with PAH, functional class III who have stable PAH on a stable drug regimen of two pulmonary arterial hypertension specific medications.

Inclusion Criteria:

• Patient with known pulmonary arterial hypertension (PAH), diagnosed as idiopathic PAH, connective tissue disease PAH, Anorexogen induced or Heritable PAH
• PAH diagnosis confirmed by hemodynamic evaluation performed prior to screening and showing all of the following: Mean pulmonary artery pressure (mPAP) ≥25 mmHg at rest; Pulmonary capillary wedge pressure (PCWP) or left ventricular end diastolic pressure (LVEDP) ≤15 mmHg; Pulmonary vascular resistance (PVR) at rest >3 Wood units; Not meeting the criteria for a positive vasodilator response (fall in mPAP ≥ 10 mmHg to ≤ 40 mmHg).
• Patient with a current diagnosis of WHO functional class III
• Patient taking two pulmonary arterial hypertension specific medications other than parenteral prostanoids
• Patient is adhering to a stable drug regimen (i.e., with no changes of dose or medication for a minimum of 3 months prior to enrollment)
• Patient with eGFR levels of ≥ 30 ml/min/1.73m2or serum creatinine levels of ˂ 150µmol/l

Exclusion Criteria:

• Patients who are treated with parenteral prostanoids
• Pregnant women or women planning a pregnancy within 12 months of study enrolment
• Patient with significant co-morbid condition(s) which, at the discretion of the PI, are deemed to prohibit study entry
• Patient with life expectancy of less than a year
• Concurrent enrollment in another device or drug trial except for observational studies (unless specifically approved by the sponsor)
• Patient with pulmonary artery anatomy that precludes treatment
• Patient with moderate to severe pulmonary artery stenosis
• Patient with any pulmonary artery aneurysm
• Patient who has experienced a myocardial infarction, unstable angina pectoris, or a cerebrovascular accident in the previous 6 months
• Patient who has implantable cardiac pacemakers, ICDs, neurostimulators, or drug infusion devices
• Patients who are unable to undergo an MRI scan