Canonical: https://echosuite.app/guides/asd/

# Atrial septal defect: shunt and Doppler calculator

Explore the atrial septal defect tool’s anatomy, shunt and Doppler teaching, with the measurements and sources for its available methods.

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

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

## Method

Qp/Qs = (Dpulmonary² × VTIpulmonary) / (DLVOT² × VTILVOT); atrial mean ΔP is directly traced

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

### Clinical question

Enter the measured value in the displayed unit

- Shunt flow · Qp/Qs
- Atrial Doppler mean
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### RVOT diameter at the PW sample  cm

2D echo · inner-edge measurement

- Use the specified view and cardiac phase.
- Align the calipers perpendicular to the structure’s long axis.
- Measure inner edge to inner edge and avoid oblique foreshortening.

### RVOT VTI  cm

Pulsed-wave Doppler

- Place the sample volume at the specified annulus or outflow tract.
- Align the Doppler beam with flow and record a clean envelope.
- Trace the modal velocity envelope and use the reported VTI.

### LVOT diameter at the PW sample  cm

2D echo · inner-edge measurement

- Use the specified view and cardiac phase.
- Align the calipers perpendicular to the structure’s long axis.
- Measure inner edge to inner edge and avoid oblique foreshortening.

### LVOT VTI  cm

Pulsed-wave Doppler

- Place the sample volume at the specified annulus or outflow tract.
- Align the Doppler beam with flow and record a clean envelope.
- Trace the modal velocity envelope and use the reported VTI.

### Atrial physiology

Enter the measured value in the displayed unit

- Not established
- Isolated ASD
- Complex CHD / atrial egress
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Traced atrial 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

ASE / SCAI · ACC / AHA · 2026 · ASD anatomy, Doppler flow and integrated assessment · ASE/SCAI 2015 pp. 912–916, 924–930, 932–935 · ASE pediatric TTE 2024 p. 142 · ACC pediatric guidance 2026

[Primary reference](https://doi.org/10.1016/j.echo.2015.05.015)

- Anatomy and acquisition · Silvestry et al. JASE 2015;28:910–958 · pp. 912–916, 924–930 · doi:10.1016/j.echo.2015.05.015

Defect morphology, surrounding structures and outflow stroke-volume ratio. Subcostal orthogonal imaging helps avoid apical dropout; significant semilunar regurgitation limits flow estimation.

- Current pediatric imaging · Lopez et al. JASE 2024;37:119–170 · p. 142 · doi:10.1016/j.echo.2023.11.015

Subcostal/right parasternal septal imaging, full-cycle PW direction, orthogonal size/rims and relationships to veins and AV valves.

- Context for the 1.5 reference · 2025 ACHD guideline §4.1.1 · doi:10.1016/j.jacc.2025.09.006; 2026 ACC pediatric shunt guidance · doi:10.1016/j.jacc.2025.11.020

Shunt ratio is interpreted with right-heart enlargement and population-specific hemodynamics. This tool does not implement closure eligibility or a PVR estimate.

- Restriction is lesion-specific · Atrial septal defect morphology and stenting in HLHS after hybrid palliation, 2017 · PMID 28889828

A selected HLHS cohort combined Doppler gradient and clinical signs. It does not validate universal mild/moderate/severe bands for all ASDs; none are applied here.

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.

## Keep exploring

- [Subcostal four chamber acquisition guide](https://echosuite.app/guides/views/subcostal-four-chamber/) · [Open in Probe Lab](https://echosuite.app/#subcostal4c)
- [Apical four chamber acquisition guide](https://echosuite.app/guides/views/apical-four-chamber/) · [Open in Probe Lab](https://echosuite.app/#a4c)
- [RV outflow acquisition guide](https://echosuite.app/guides/views/rv-outflow/) · [Open in Probe Lab](https://echosuite.app/#rvOutflow)
- [Qp/Qs calculator: pulmonary to systemic flow ratio](https://echosuite.app/guides/qpqs/)
- [VSD · size & right-heart pressure calculator](https://echosuite.app/guides/vsd-pressure/)
- [PDA · shunt & PA pressure calculator](https://echosuite.app/guides/pda-pressure/)
- [Coarctation · anatomy & gradients calculator](https://echosuite.app/guides/coarctation/)

[All echo guides](https://echosuite.app/guides/) · [Learning paths](https://echosuite.app/learn/)