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Updated: May 9, 2026
Non-invasive Assessment of Microvascular and Endothelial Function
Published on: January 29, 2013
Noninvasive assessment of vascular function and hydraulic power and efficiency in pediatric Fontan patients
Kimberley A Myers1, Mande T Leung1, M Terri Potts1
1Children's Heart Centre, British Columbia Children's Hospital, and the Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.
Insights
Children with Fontan circulation have stiffer aortas and generate more hydraulic power, despite similar hydraulic efficiency. Therapies should address both ventricular function and vascular stiffness in Fontan patients.
Area of Science:
- Pediatric Cardiology
- Vascular Physiology
- Biomedical Engineering
Background:
- Children with Fontan palliation exhibit abnormal arterial stiffness, impedance, and hydraulic power.
- Invasive studies suggest these abnormalities, but noninvasive assessment is crucial.
Purpose of the Study:
- To noninvasively assess arterial stiffness, impedance, and hydraulic power in children with Fontan circulation.
- To compare these hemodynamic parameters with those of healthy children.
Main Methods:
- A case-control study involving 22 Fontan patients and 31 healthy controls.
- Doppler echocardiography and carotid artery applanation tonometry were used to measure aortic flows, dimensions, and pulse-wave velocity.
- Vascular impedance, arterial stiffness, hydraulic power, and efficiency were calculated.
Main Results:
- Fontan patients had higher aortic cross-sectional area, peak aortic flow, and myocardial performance index, with lower ejection fraction.
- Pulse-wave velocity, elastic pressure-strain modulus, and stiffness index were higher in Fontan patients, indicating stiffer aortas.
- Despite lower input impedance, Fontan patients generated higher total hydraulic power with similar hydraulic efficiency.
Conclusions:
- Fontan patients exhibit stiffer aortas and increased hydraulic power generation linked to decreased ventricular function, yet maintain similar hydraulic efficiency.
- Therapeutic interventions for Fontan patients should consider targeting vascular stiffness alongside ventricular function.
- Noninvasive Doppler echocardiography and tonometry can monitor the efficacy of interventions for Fontan circulation.
Background:
Invasive studies have shown that children with Fontan palliation have abnormal arterial stiffness, impedance, and hydraulic power and efficiency. The aim of this study was to assess these indexes noninvasively in a cohort of children with Fontan circulation using Doppler echocardiography and compare their results with those of healthy peers.
Methods:
This was a case-control study of 22 Fontan patients and 31 healthy control children. Using standard two-dimensional, M-mode, and Doppler echocardiographic imaging and carotid artery applanation tonometry, aortic flows, dimensions, and pulse-wave velocity were measured, and vascular impedance and arterial stiffness were calculated. Hydraulic power and efficiency were calculated from standard fluid dynamics formulae.
Results:
The median age was similar between groups. Stroke volume index (39 vs 39 mL/min/m(2)) and cardiac index (2.6 vs 2.5 L/min/m(2)) were similar. Aortic cross-sectional area (3.3 vs 2.8 cm(2)), peak aortic flow (302 vs 261 cm(3)/sec), and myocardial performance index (0.47 vs 0.25) were higher and ejection fraction (50% vs 66%) was lower in Fontan patients. Input impedance (61 vs 83 dyne · sec/cm(5)/m(2)) was lower in Fontan patients. Pulse-wave velocity (488 vs 364 cm/sec), elastic pressure-strain modulus (305 vs 263 torr), and stiffness index (4.15 vs 3.04) were higher in Fontan patients. Total arterial compliance (1.29 vs 1.32 mL/torr/m(2)) and mean power (606 vs 527 mW/m(2)) were similar and total hydraulic power (716 vs 627 mW/m(2)) was higher in Fontan patients. Efficiency and the power cost per unit of forward flow were similar.
Conclusions:
Despite stiffer aortas, Fontan patients generate more hydraulic power associated with decreased ventricular function to achieve a similar hydraulic efficiency. In Fontan patients, therapy that is given to improve ventricular function may need to target vascular stiffness as well. This technique may be used to monitor the efficacy of therapeutic interventions.
