Canonical: https://echosuite.app/guides/fontan-gradient/

# Fontan · circulation & gradients calculator

Explore fontan · circulation & gradients with the method’s inputs, acquisition guidance and source references. Open the calculator to enter measurements or try an illustrative worked example.

Created by [Mohammed Kamareddine, MD](https://echosuite.app/about/) · [Sources & educational scope](https://echosuite.app/about/)

[Open interactive calculator →](https://echosuite.app/calculators/#fontan-gradient)

## Method

Doppler mean ΔP = time average of 4v(t)² over the traced interval

Use the measurement units shown below. Some fields apply only to a selected method or condition; follow the interactive tool’s method choices. The interactive tool keeps missing measurements incomplete and provides its method-specific results and reference context.

## Measurements and acquisition

### Measured site

Enter the measured value in the displayed unit

- Fenestration
- Fontan–PA connection
- IVC–Fontan connection
- Glenn connection
- Branch pulmonary artery
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Traced mean gradient  mmHg

Complete traced CW envelope

- Align through the valve or shunt and record a complete envelope.
- Trace the modal velocity envelope using the machine tool.
- Use the machine-calculated mean gradient in mmHg.

## Sources and method context

EACVI · ASE · AHA / ACC · 2025 · Fontan circulation: imaging, acquisition and hemodynamic limitations · EACVI 2018 p. 1094 · ASE Echo May/June 2025 pp. 24–27 · Sanders et al. 2025

[Primary reference](https://doi.org/10.1093/ehjci/jey102)

- Site-specific adult reference · EACVI 2018 · p. 1094, Fontan circulation · doi:10.1093/ehjci/jey102

Fenestration mean 4–8 mmHg is a contextual reference; a cavopulmonary connection mean of 3 mmHg may be important. No universal Fontan severity grade is supplied.

- Map connections and acquire the correct spectrum · Klug & Kwon · ASE Echo May/June 2025 · pp. 24–27, Fontan Imaging Tips (educational article)

Identify the operation, examine both Glenns when present, optimize low-velocity flow, use PW at connections and CW for the fenestration mean.

- Fenestration gradient is an imperfect surrogate · Sanders et al. · Pediatr Cardiol 2025;46:2047–2053 (online 2024) · PMID 39395055 · doi:10.1007/s00246-024-03651-1

Retrospective 59-patient comparison; echo within six months of catheterization. Limited agreement does not support treating Doppler as direct catheter pressure or applying a regression conversion.

- Whole-circulation assessment · 2025 ACHD guideline · Fontan palliation section · doi:10.1016/j.jacc.2025.09.006; AHA Fontan statement 2019 · doi:10.1161/CIR.0000000000000696

Evaluate ventricular/valvar function, pathway and venous obstruction, collaterals, rhythm and end-organ effects; unexplained deterioration may require expert invasive assessment.

Catalogue review status: Exact guideline locator mapped · clinical sign-off pending

These pages describe the educational tool. Interpret measurements with the complete clinical context and the method’s acquisition limitations.

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