Pulmonary Capillary Recruitment in Fontan Patients

Pulmonary Capillary Recruitment With Pulmonary Vasodilator Therapy in Patients With Univentricular Heart Physiology and Failing Total Cavo-pulmonary Connection.

This study evaluates the effects of pulmonary vasodilator therapy on pulmonary capillary blood flow by measuring the functional capillary surface area (FCSA) at baseline and post nitric oxide inhalation, through the injection of 3H-benzoyl-Phe-Ala-Pro (BPAP). FCSA will be related to flow and other hemodynamic parameters in order to determine if there is capillary recruitment or distention in Fontan patients. We will also compare baseline FCSA measurements with previously studied normal subjects, to assess the difference in hemodynamic pulmonary functional parameters between these single ventricle physiology patients and normal subjects.

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.

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