Sildenafil tested in adults with a single-ventricle heart after Fontan surgery

Who can take part

• Functionally univentricular heart
• Post-Fontan operation condition with the creation of a total cavo-pulmonary connection (TCPC) either extracardiac [extracardiac conduit] or intracardiac [lateral intra-atrial tunnel]
• No clinical indications for cardiac catheterization
• Age > 18 years
• Informed consent to participate in the study

Who cannot take part

• Patients with concomitant diagnoses of: a) cardiovascular events within the last 3 months (acute coronary syndrome, sudden cardiac arrest, ventricular arrhythmias, intracranial hemorrhage, stroke), b) pulmonary embolism, c) infections, d) active bleeding complications, e) severe liver failure (Child-Pugh class C), f) active gastric and/or duodenal peptic ulcer disease, g) malignancy, h) primary muscle and nervous system disease, i) systemic connective tissue disease, j) myocarditis and/or pericarditis, k) predisposition to priapism, sclerosis of the corpus cavernosum or Peyronie's disease, l) sickle cell anemia, leukemia, or multiple myeloma, m) loss of vision in one eye due to non-arteritic anterior ischemic optic neuropathy (NAION), n) enteropathy with protein loss
• Taking products containing nitric oxide or nitrates in any form (e.g., nitroglycerin, isosorbide mononitrate, isosorbide dinitrate, amyl nitrate, pentaerythritol tetranitrate); use in combination with the most potent CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir)
• Patients who were taking pulmonary arterial dilators (sildenafil, tadalafil, riociguat, bosentan, macitentan, ambrisentan, epoprostenol, iloprost, selixipag) in the 6 month period preceding study entry, regardless of the duration of therapy and route of administration (oral, intravenous, subcutaneous, inhalated)
• Patients with a functionally univentricular heart within 6 months of their last cardiac operation or intravascular procedure
• Advanced heart failure (NYHA IV)
• Atrial arrhythmia preventing the execution/interpretation of the above-mentioned tests or a life-threatening exercise-induced arrhythmia history
• Chronic kidney disease (creatinine > 150 µmol/l)
• Liver damage manifested by a twofold increase in transaminases above the norm
• Non-use of contraception during the study - applies to women of reproductive age
• Pregnancy (positive pregnancy test result), planning pregnancy, breastfeeding
• Severe central nervous system damage
• Patients unable to undergo egrospirometric examination
• Resting arterial oxygen saturation <85%
• Uncontrolled hypotension (blood pressure < 90/50 mmHg) or risk of hypotension (dehydration, systemic ventricular outflow tract obstruction, autonomic nervous system dysfunction, patients taking alpha-blockers)