Z-Scale Chart

The horizontal axis (x-axis) is Body Surface Area axis. Calculate your Body Surface Area by going to this site: http://www.halls.md/body-surface-area/bsa.htm, and typing in the required values.

Now if your BSA is 1.79 (height 192cm, weight 60kg), look in the chart, on the horizontal axis, and mark a point approximately where 1.79 lies. Now check if your aortic root at Sinuses of Valsalva fall within the safe zone (the greyed out area). For "Young adults" with a BSA of 1.79, the safe aortic diameters are from 2.5 to 3.4 cm diastole.





The Aorta is a long pipe that is NOT uniform in diameter. Measuring the aortic diameter at a random location, via a echo-cardiogram or CT, is of no use if your purpose is to compare your aortic diameter against a statistically significant percentage of the population, which is what the Z scale is all about. The reading is taken at the Sinuses of Valsalva at diastole! Also note that: what is considered a "safe" aortic value may vary, as indicated by the second and third image. The second image is taken from: "Essential Echocardiography - Scott Solomon" and the third one from: "Feignebaum's Echocardiography, 6e". The most accurate way is to compare your body mass using the Z-scale ans see if you lie within a statistics based safe zone.



Note the 4 positions where you need to take the aortic measurements for Marfan's patients. The radiographic view is the PLAX - Parasternal Long Axis View and the mode is 2 Dimensional (2D mode).