Inclusion Criteria:

• * Eligible and randomized in the trial NCT02836899
• * Provide written informed consent
• * Age ≥ 18 years of age
• * Elective cardiac or aortic surgery with CPB \>90 minutes
• * Clinical evidence of endothelial dysfunction assessed by a specifically designed questionnaire

Exclusion Criteria:

• * Estimated Glomerular Filtration Rate less than 30 ml/min/1.73 m2
• * Emergent cardiac surgery
• * Life expectancy \< 1 year at the time of enrollment
• * Hemodynamic instability as defined by a systolic blood pressure \<90 mmHg.
• * Mean pulmonary artery pressure ≥ 40 mm Hg and PVR \> 4 Wood Units.
• * Left ventricular ejection fraction \< 30% by echocardiography obtained within three months of enrollment
• * Administration of one or more Packed Red Blood Cell (PRBC) transfusions in the week prior to enrollment
• * X-ray contrast infusion less than 48 hours before surgery
• * Evidence of hemolysis from any other origin:
• a. Intravascular: i. Intrinsic RBC defects leading to hemolytic anemia (eg, enzyme deficiencies, hemoglobinopathies, membrane defects) ii. Extrinsic: liver disease, hypersplenism, infections (eg, bartonella, babesia, malaria), treatment with oxidizing exogenous agents (eg, dapsone, nitrites, aniline dyes), exposure to other hemolytic agents (eg, lead, snake and spider bites), lymphocyte leukemia, autoimmune hemolytic disorders b. Extravascular: Infection (eg, clostridial sepsis, severe malaria), paroxysmal cold hemoglobinuria, cold agglutinin disease, paroxysmal nocturnal hemoglobinuria, iv infusion of Rho(D) immune globulin, iv infusion of hypotonic solutions