Background: Survivors with Fontan circulation suffer from chronic systemic hypoperfusion resulting in end-organ injury. Little is known about the effects of these hemodynamic perturbations on bone. We hypothesized that chronic Fontan circulation (>5 years after surgery) would be associated with bone deficits.
Methods: Peripheral quantitative computed tomography (pQCT) was performed on 10 Fontan patients (seven males, 11.8±1.7 years) and 11 healthy controls (nine males, 12.0±1.5 years) with Tanner stage ≤3. Height-adjusted Bone Mineral Density Z-scores for lumbar spine (LBMD) and total body less head (TBLH) were also measured in Fontan patients by dual energy x-ray absorptiometry (DXA). Linear regression was used to compare radius pQCT measures of bone strength index (BSI), trabecular (3% site) and cortical (33% site) volumetric BMD (vBMD) and thickness between Fontan patients and controls (with adjustment for radius length, age, and sex), and to correlate pQCT outcomes with DXA Z-scores.
Results: The adjusted differences in means (95% CI) for Fontan patients vs. controls were: −28.1 mg/cm3 (−54.8, −1.34; P=0.040) for trabecular vBMD, −10.9 mg/cm3 (−49.8, 28.0; P=0.584) for cortical vBMD, −0.35 mm (−0.64, −0.06, P=0.017) for cortical thickness, and −7.2 mg2/mm4 (−13.7, −0.8; P=0.028) for BSI. Mean height-adjusted LBMD Z-score was −0.46±1.1 and TBLH Z-score was −0.63±1.1. LBMD Z-scores were trending higher by 0.39 (−0.006, 0.78; P=0.054) per 20 mg/cm3 of trabecular vBMD among Fontan subjects.
Conclusions: Children with Fontan palliation have lower trabecular vBMD, cortical thickness, and bone strength. This suggests that bone is another target organ sensitive to the Fontan physiology. Among pQCT outcomes, trabecular vBMD showed a similar trend as LBMD, underscoring a potential utility of DXA as a monitoring tool. Further studies should evaluate the etiology and impact on fracture risk of these deficits.
28 - 31 May 2016
European Society of Endocrinology