A Study to Evaluate the Efficacy, Safety and Tolerability of PDNO Infusion in Patients With Pulmonary Hypertension After Cardiopulmonary Bypass Surgery

Inclusion Criteria: Ability to understand and willing to sign an informed consent form (ICF) Male and female patients, age ≥ 18 years Planned to undergo elective cardiopulmonary bypass (CPB) for coronary artery bypass grafting (CABG), aortic valve repair (AVR) or mitral valve repair (MVR) with or without CABG Diagnosed with echocardiographic signs of pulmonary artery systolic pressure (PASP) >50 mmHg , as estimated by doppler defined echocardiography using a modified Bernoulli equation: PASP ≈ 4 (tricuspid regurgitant jet velocity)^2 + central venous pressure (CVP) Exclusion Criteria: History of chronic pulmonary hypertension (PH) (WHO group 1, 3, 4 or 5), not group 2 due to left heart disease Patients with contraindications for pulmonary artery catheter (PAC) History of severe chronic obstructive pulmonary disease Left heart failure with ejection fraction (EF) <35% Non-ST elevation myocardial infarction (non-STEMI) or ST elevation myocardial infarction (STEMI) within 1 months prior to informed consent Stroke (cerebrovascular lesion [CVL]), transient ischemic attack (TIA), AV block III within 3 months prior to informed consent or QTcF >450ms at the time of screening High inotropic requirement (no more than one inotrope treatment and the vasopressor norepinephrine at time of screening/postoperative evaluation) (Increased) mediastinal bleeding >100 mL/hour in mediastinal drainage at postoperative evaluation Mechanical circulatory assistance (intra aortic balloon pump [IABP] or right/left-ventricular assist device [R/L VAD]) Echocardiographic evidence of significant tricuspid insufficiency Body Mass Index (BMI) >40 kg/m^2 Estimated glomerular filtration rate (eGFR) < 30 mL/min preoperative value Methemoglobin >3% Indication of liver disease, defined by serum levels of either alanine aminotransferase (ALT), aspartate aminotransferase (AST) or alkaline phosphatase (ALP) above 3 x upper limit of normal (ULN) (preoperative value) Preoperative haemoglobin <10 g/dL, postoperative: Hb < 9 g/dL Thrombocytopenia (platelet count <100,000/mm^3), preoperative value Prothrombin time International ratio (INR) > 1.3, preoperative value Pregnant or lactating women, or with a positive pregnancy test at screening (for fertile women only) Ongoing daily treatment the last 3 days with non-steroidal anti-inflammatory drugs (NSAIDs, excluding low dose, i.e. 75 mg, acetylsalicylic acid), new oral anticoagulants (NOACs), warfarin, heparin, clopidogrel (last 5 days). Low molecular weight heparin (LMWH) is not an exclusion criterion. Any use of PDE5 inhibitors (sildenafil, tadalafil, vardenafil and avanafil) within 48 hours prior to the administration of PDNO. Known active malignancy within the past 3 years except for localized prostate cancer, cervical carcinoma in situ, breast cancer in situ, or nonmelanoma skin cancer that has been definitively treated History of allergy/hypersensitivity to PD or ongoing allergy/hypersensitivity or history of hypersensitivity to drugs with a similar chemical structure or class to PDNO History of any other clinically significant disease or disorder Participation in any interventional clinical study or has been treated with any investigational research products within 30 days or 5 half-lives, whichever is longer, prior to the initiation of screening