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Bone-Specific Alkaline Phosphatase in Patients Who Have Undergone the Fontan Operation
Andrew Schiff1, Joshua Yang1,2, Lawrence H Winner3
1University of Central Florida School of Medicine, Orlando, FL, USA.
Insights
Bone-specific alkaline phosphatase (BALP) in children with Fontan circulation was not linked to cardiac index (CI). However, BALP z-scores showed a near-significant association with mixed venous oxygen saturation, suggesting BALP may indicate oxygen delivery.
Area of Science:
- Pediatric Cardiology
- Biomarkers
- Congenital Heart Disease
Background:
- Fontan circulation is associated with low cardiac index (CI).
- Bone-specific alkaline phosphatase (BALP) is produced by osteoblasts.
- Previous studies suggested a link between CI and BALP in Fontan patients.
Purpose of the Study:
- To investigate the association between BALP z-score and CI in children post-Fontan operation.
- To explore the relationship between BALP z-score and other hemodynamic variables, including oxygen saturation.
Main Methods:
- Prospective enrollment of 15 pediatric patients undergoing cardiac catheterization after Fontan operation.
- Measurement of serum BALP levels and calculation of age-/gender-specific BALP z-scores.
- Analysis of associations between BALP z-score, CI, and mixed venous oxygen saturation (SVC and IVC).
Main Results:
- BALP z-score showed no significant association with cardiac index (CI).
- A positive correlation was observed between BALP z-score and superior vena cava (SVC) saturation (p=0.07).
- A trend towards significance was noted for the association between BALP z-score and average SVC/IVC saturation (p=0.052).
Conclusions:
- BALP z-score is not associated with CI in children with Fontan circulation.
- BALP may serve as a potential biomarker for oxygen delivery in this patient population.
- Further research is warranted to validate BALP as a marker of oxygen delivery in Fontan patients.
Abstract:
Bone-specific alkaline phosphatase (BALP) is produced by osteoblasts. A recent series noted a positive association between cardiac index (CI) and BALP in patients with Fontan circulation. CI is low at baseline in these patients, and small decreases in CI may result in diverting of blood away from bone. We prospectively enrolled 15 patients (males ≤ 14 yo, females ≤ 12 yo) who had previously undergone Fontan operation and were undergoing cardiac catheterization. Serum BALP was measured at catheterization, and analysis performed to evaluate association between age-/gender-specific BALP z-score and CI as well as other patient variables. The median age at catheterization was 5.6 years (3.1-13.1), and time from Fontan was 1.5 years (0.1-12.1). The median superior vena cava saturation (SVC) was 65 % (52-74), median average between SVC and inferior vena cava (IVC) saturations was 62.5 % (51-70), and median CI was 3.8 L/min/m(2) (2.0-8.4). The median BALP was 65 IU/L and BALP z-score was -2.1 (-3.2 to 0.9). BALP z-score was not associated with CI (ρ = -0.1, p = 0.7), but a positive correlation was noted with the average of SVC and IVC saturation (ρ = 0.5, p = 0.052) and with SVC saturation (ρ = 0.4, p = 0.07), both nearly reaching statistical significance. In our cohort of children with Fontan circulation undergoing catheterization, BALP z-score was not associated with CI, but an association with estimates of mixed venous saturation was noted that nearly reached statistical significance. We hypothesize that BALP is a marker of oxygen delivery in those with Fontan circulation and may represent a valuable biomarker in this population.
