Canonical: https://echosuite.app/guides/pda-pressure/

# PDA · shunt & PA pressure calculator

Explore pda · shunt & pa pressure 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/#pda-pressure)

## Method

Systolic ΔP = 4Vsys²; estimated PASP = SBP − ΔP; estimated mPAP = MAP − complete-cycle mean ΔP

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

- PA systolic pressure
- Mean PA pressure
- Ductal gradient only
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Observed ductal flow

Enter the measured value in the displayed unit

- Not established
- All left → right
- Bidirectional
- All right → left
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Peak systolic PDA velocity  m/s

Continuous-wave Doppler

- Align the CW cursor as parallel as possible to the jet.
- Acquire a dense, complete envelope without truncation.
- Measure the highest absolute velocity on the selected envelope.

### Systolic blood pressure  mmHg

Contemporaneous cuff or invasive value

- Use a pressure obtained in the same hemodynamic state as the echo.
- Confirm the value is entered in mmHg.
- Do not mix values acquired under different loading conditions.

### Complete-cycle 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.

### Mean arterial pressure  mmHg

Contemporaneous cuff or invasive value

- Use a pressure obtained in the same hemodynamic state as the echo.
- Confirm the value is entered in mmHg.
- Do not mix values acquired under different loading conditions.

## Sources and method context

ASE · AHA / ACC · primary Doppler studies · 2025 · PDA acquisition, pressure estimation and whole-shunt assessment · ASE pediatric TTE 2024 pp. 162–163 · TNE 2024 pp. 185–188, Table 5 · Musewe et al. 1987

[Primary reference](https://doi.org/10.1016/j.echo.2023.11.015)

- Locate the duct and record the whole cycle · Lopez et al. JASE 2024;37:119–170 · pp. 162–163 · doi:10.1016/j.echo.2023.11.015

High parasternal sagittal and suprasternal color sweeps; assess restriction and direction throughout the cycle. Abdominal holodiastolic reversal has other causes.

- Conditional pressure estimates · Musewe et al. Circulation 1987;76:1081–1091 · PMID 2959394; Lu et al. 1991 · PMID 1806337

Small simultaneous Doppler/catheter studies support systolic and mean estimates in appropriate PDA flow. Right-to-left velocity did not correlate with pressure in the Musewe series; this tool restricts subtraction to continuous left-to-right flow.

- Geometry and timing limitations · Duct-geometry study 1987 · PMID 3329223; Spach et al. Circulation 1980;61:110–122 · doi:10.1161/01.CIR.61.1.110

Duct configuration can distort Bernoulli estimates; instantaneous pressure separation and shunt direction change during the cardiac cycle.

- Hemodynamic significance is multiparametric · ASE targeted neonatal echo 2024 · pp. 185–188, Table 5 p. 197 · doi:10.1016/j.echo.2023.11.016; 2025 ACHD guideline §4.1.5 · doi:10.1016/j.jacc.2025.09.006

Assess chamber/flow response and systemic runoff in their population context. Adult decisions incorporate net shunt, LV effects and PVR; no automated significance, PAH grade or closure recommendation is supplied.

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

- [Qp/Qs calculator: pulmonary to systemic flow ratio](https://echosuite.app/guides/qpqs/)
- [Atrial septal defect: shunt and Doppler calculator](https://echosuite.app/guides/asd/)
- [VSD · size & right-heart pressure calculator](https://echosuite.app/guides/vsd-pressure/)
- [Coarctation · anatomy & gradients calculator](https://echosuite.app/guides/coarctation/)

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