Nitrate Effect on Exercise Capacitance

Phase 2

Completed

Brief Summary: The investigators will investigate the safety and preliminary efficacy of ISDN therapy to reduce venous congestion and improve exercise tolerance in children and adults after the Fontan operation. This will be accomplished by recruiting 15 Fontan physiology patients from the Cincinnati Children's Fontan clinic and University of Kentucky Pediatric Cardiology clinic for the investigation. The investigators will non-invasively measure both central venous pressures at rest and during graded cardiopulmonary exercise testing. In addition the study team will obtain a measurement of liver stiffness before and after a 4-week regimen of ISDN therapy. Patients will be seen twice in clinic, once before and after ISDN therapy, and phone calls will be made to ensure safety, compliance, and make appropriate alterations to medications throughout the study period. Pre- and post-intervention central venous pressure and exercise tolerance will be compared.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Isosorbide Dinitrate	Isosorbide Dinitrate	Each enrolled participant will be on a titrated dosage of isosorbide dinitrate to determine effectiveness on both primary and secondary outcome measures.

Primary Outcome Measures

Name	Time	Method
Number of Participants Who Experience an Adverse Reaction to the Study Medication During the Study Enrollment Period.	Baseline and 6 weeks	Potential adverse side effects of study medication (isosorbide dinitrate) will be monitored throughout study period. Study medication will be titrated to a maximal dose of 30mg dependent on the patient tolerance. Patient tolerance is defined by frequency of known risk factors to the study medication (headaches, hypotension, and syncope).

Secondary Outcome Measures

Name	Time	Method
Effect of Isosorbide Dinitrate on Liver Stiffness Levels	Baseline and 6 weeks	Determine effectiveness of study medication on hemodynamic profile by completing baseline and post-study medication liver ultrasound measuring liver stiffness levels by sheer wave speed (m/s).
Effect of Isosorbide Dinitrate on Central Venous Pressure	Baseline and 6 weeks	Determine effectiveness of study medication on hemodynamic profile by completing baseline and post-study medication maximal exercise tests to measure central venous pressure via IV catheter insertion
Effect of Isosorbide Dinitrate on Maximal Exercise Capacity VO2 Max	Baseline and 6 weeks	Obtain estimates of the effect the study medication has on maximal exercise test VO2 max performance in Fontan patients by study participants performing a maximal ramp exercise test on a stationary bike.
Effect of Isosorbide Dinitrate on Maximal Exercise Capacity Heart Rate Response	Baseline and 6 weeks	Obtain estimates of the effect the study medication has on maximal exercise test heart rate response in Fontan patients by study participants performing a maximal ramp exercise test on a stationary bike.
Effect of Isosorbide Dinitrate on Maximal Exercise Capacity Respiratory Rate Response	Baseline and 6 weeks	Obtain estimates of the effect the study medication has on maximal exercise test respiratory rate response in Fontan patients by study participants performing a maximal ramp exercise test on a stationary bike.