Pulmonary Capillary Recruitment in Fontan Patients

Inclusion Criteria: Fontan failures will be defined as patients with single ventricle physiology and TCPC with clinical signs of dysfunction defined as any of the following: 1. Decreased functional class WHO/NYHA II or more and clinical signs of congestion (ascites, peripheral edema, increased JVP) and/or NT-proBNP \> 399 pg/ml based on \[17\]. 2. Age \> 18 years 3. Known Fontan's increased pressures a. Fontan mean pressure of ≥15 mmHg and/or transpulmonary gradient ≥ 5 mmHg. b. Pulmonary vascular resistance ≥ 2 woods units. And/or supporting evidence of end-organ damage 1\. Clinical or paraclinical evidence of liver congestion and/or fibrosis a. Evidence in ultrasound or other imaging techniques of liver congestion and/or changes related to cardiac cirrhosis. b. Fibroscan with grade 2 or + 2. Paraclinical signs of portal hypertension defined as 2 or more: 1. Thrombocytopenia defined as platelet count \< 150.0000 2. Leukocytopenia defined as white blood cell less than 4.500 3. Esophageal varices on esophagoduodenoscopy. 4. Splenomegaly on imaging - Exclusion Criteria: 1. Presence of fenestration - the shunts include veno-veno collaterals 2. Significant anemia defined as Hgb \< 120 mg/dl 3. Pregnancy at the moment of the procedure. 4. Taking angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. 5. Usage of nitrates, phosphodiesterase inhibitors or calcium blockers within 3 months of the study. \-