Canonical: https://echosuite.app/guides/lap-mr/

# Left atrial pressure calculator: mitral regurgitation velocity

Explore the MR-velocity pressure estimate, its two inputs and the acquisition requirements shown with the calculation.

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

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

## Method

LAP = SBP − 4(MR Vmax)²

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

### 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.

### MR Vmax  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.

## Sources and method context

Gorcsan, Snow, Paulsen & Nixon · American Heart Journal · 1991 · Noninvasive estimation of left atrial pressure in patients with congestive heart failure and mitral regurgitation by Doppler echocardiography · Am Heart J 121:858–863 · PMID 2000753

[Primary reference](https://pubmed.ncbi.nlm.nih.gov/2000753/)

- Equation and selected-patient validation · Gorcsan et al. 1991 · abstract and pp. 858–863

Peak brachial SBP minus 4 × peak MR velocity squared; distinct envelopes in 35 of 46 patients, compared with simultaneous mean wedge pressure. This is an estimate, not a grading threshold.

- Gradient foundation · Nishimura & Tajik · JACC 1988;11:317–321 · PMID 3339169

Simultaneous dual-catheter and Doppler validation of left-sided regurgitant pressure gradients.

- MR signal interpretation · ASE 2017 native regurgitation · journal p. 330 · Continuous Wave Doppler

MR velocity reflects the LV–LA pressure difference; peak velocity alone does not quantify regurgitant severity.

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

- [Apical four chamber acquisition guide](https://echosuite.app/guides/views/apical-four-chamber/) · [Open in Probe Lab](https://echosuite.app/#a4c)
- [Apical two chamber acquisition guide](https://echosuite.app/guides/views/apical-two-chamber/) · [Open in Probe Lab](https://echosuite.app/#a2c)
- [Apical three chamber (apical long axis) acquisition guide](https://echosuite.app/guides/views/apical-three-chamber/) · [Open in Probe Lab](https://echosuite.app/#a3c)
- [Left atrial pressure calculator: E/e′ method](https://echosuite.app/guides/lap-ee/)
- [Left atrial volume index calculator: LAVI](https://echosuite.app/guides/la-size/)
- [Left ventricular pressure calculator](https://echosuite.app/guides/lv-pressure/)
- [Diastolic function assessment: sinus rhythm](https://echosuite.app/guides/diastolic-sinus/)

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