OMAM Aortic Root Z-Scores

Live page: https://parameterz.github.io/OMAM-Aortic-Root/

A single-page calculator for adult aortic root dimensions using the optimized multivariate allometric model (OMAM) equations and reference values from the CITED I study:

Yao G, Hu X, Chen X, et al. Comparison of Body Surface Area and Optimized Multivariate Allometric Model Approaches in Correcting Echocardiographic Aortic Dimensions for Physiological Variances: An International and Multicenter Study (CITED I). MedComm 2026;7(6):e70788. doi:10.1002/mco2.70788

The authors' own calculator returns only the predicted diameter (Yp) and the ratio measured/Yp. This page adds the context a practitioner needs to answer "is this normal?"

What it reports

For the aortic annulus, sinuses of Valsalva and proximal ascending aorta:

• Expected diameter (Yp) for the patient's sex, age, height and weight
• Normal range in millimetres (Yp × published lower and upper limits)
• Percent predicted (Yc = measured / Yp)
• Z-score and percentile: z = (Yc − mean) / SD
• A flag against the published 95% reference limits
• The z-score under all three reference cohorts (Chinese, Italian, combined)

Equations

Yp = a × bfemale × agex × heighty × weightz (age in years, height in cm, weight in kg)

Cohort	Site	a	b	x (age)	y (height)	z (weight)
Chinese	Ao-a	9.593	0.943	0.054	–	0.142
Chinese	Ao-s	8.085	0.949	0.113	–	0.210
Chinese	Ao-asc	5.028	0.966	0.161	–	0.261
Italian	Ao-a	1.042	0.944	0.054	0.472	0.081
Italian	Ao-s	2.268	0.925	0.164	0.317	0.090
Italian	Ao-asc	6.385	0.956	0.204	–	0.175
Combined	Ao-a	2.948	0.928	0.060	0.338	–
Combined	Ao-s	2.689	0.950	0.137	0.210	0.198
Combined	Ao-asc	4.375	0.974	0.180	–	0.280

Coefficients match the paper and the authors' published calculator.

Reference values

• Chinese and Italian: mean ± SD and 95% limits of Yc from Table 5 (n = 910 each). The normal/abnormal flag uses these limits, as the authors recommend.
• Combined: the paper publishes no reference values for this model. The page uses the sex-specific validation-group (group B) mean ± SD from Table 4, with limits at mean ± 1.96 SD. These are provisional.
• "High-normal" / "low-normal" (inside the limits but beyond the 95th / 5th percentile) is this page's addition, not the authors'.

Limitations

• Derived in healthy, normotensive, non-obese (BMI < 30) adults aged 18–79; athletes and pregnant women excluded.
• Age is in every equation, so age-related dilation is treated as normal.
• All sites measured leading edge to leading edge at end-diastole in the parasternal long axis. This differs from the ASE convention for the annulus (inner edge, mid-systole).
• Only Han Chinese and Italian subjects were studied.

For research and education. It does not replace clinical judgement.

Features

• Expected diameter, percent of expected, Z-score and percentile for each site.
• Normal range in millimetres for the patient, on each bar and in the calculation panel.
• Flags against the published 95% limits: normal, high-/low-normal, above/below normal.
• Same patient under all three cohorts, side by side.
• Height in cm or inches and weight in kg or pounds. Values are stored in metric, so switching units never drifts.
• Step-by-step calculation for any site.
• Print report: a one-page summary with demographics, measured values, normal ranges and Z-scores.
• Copy report text: the same summary as plain text, to paste into an echo report.
• Provenance: reports and copied text record the calculator version, URL, equation source, method, author and generation time.

Layout

index.html          page markup
css/styles.css      styles (light and dark)
js/equations.js     coefficients and reference values as data
js/zscore.js        pure calculation functions
js/units.js         unit conversion, BMI and BSA
js/app.js           UI, printable report and copy-to-text
js/version.js       version and provenance (footer, report, copied text)
vendor/rough.esm.js rough.js 4.6.6 (MIT), for the sketched Z-bars
tests/              node:test checks, including the authors' calculator output

A correction to the equations is a change to js/equations.js only.

Run locally

No build step. ES modules need a local server rather than file://:

python3 -m http.server 8000     # then open http://localhost:8000/
npm test                        # Node 18+; no dependencies

Deploy

GitHub Pages, from the root of main.

Credits

Created by Dan Dyar, MA, ACS, RDCS, FASE. Visual style after The Heart by Ultrasound. Sketched figures drawn with rough.js.

License

Code: MIT (see LICENSE). The equations belong to the cited article; please cite it when using them.