Nephropathy in patients after Fontan palliation

As the effect of Fontan circulation on the kidneys has not been defined, the purpose of this study was to determine whether it is associated with nephropathy.

Patients with single ventricle physiology at least 2 years after Fontan procedure with normal cardiac function by echocardiography, history of normal renal ultrasound, and no co-morbidities known to affect the kidneys were evaluated. Patient's demographics, diagnoses, pre- and post-Fontan catheterization data, and current medications were collected. A current glomerular filtration rate (eGFR) was calculated. Morning urine samples were collected for microalbumin/creatinine ratio (MCR).

Twenty-one subjects (M:F=13:8, ages 15.2+/-8.8 years) were studied. Primary diagnoses included hypoplastic left ventricle in 9, forms of hypoplastic right ventricle in 10, and unbalanced atrio-ventricular canal in 2 patients. Time after Fontan completion was 11.4+/-6.5 years. Current medications included aspirin (14 patients), coumadin (4), enalapril (8), lisinopril (10), digoxin (11), diuretics (5), and beta-blockers (5). Four subjects had pacemakers. All patients had a normal blood pressure and eGFR. Nine patients (43%) had a pathologic MCR (>20 microg/mg). There were no significant differences between the MCR-normal and MCR-abnormal groups in age, gender, type of single ventricle, type of the procedure, age at or time since Fontan operation. The groups differed in post-Fontan pulmonary vascular resistance (PVR) (p<0.01) and strong positive correlations were found between the MCR and pre- and post-Fontan PVR (r=0.51, p<0.05 and r=0.61, p=0.02 respectively). The MCR-normal and MCR-abnormal groups did not differ in pacemaker, digoxin, diuretics, or anticoagulant use. However, the groups were different in using ACE inhibitors with a negative correlation (r=-0.45, p=0.04) between the MCR and lisinopril-equivalent ACE inhibitor dose. Moreover, no patient receiving a lisinopril-equivalent dose greater than 0.4 mg/kg/day had pathologic microalbuminuria. In conclusion, our study demonstrates that patients with Fontan circulation have high incidence of pathologic microalbuminuria, an indicator of renal injury. The use of ACE inhibitors may be beneficial in preserving their renal function.