Coronary Artery Z-Scores

Primarily useful for patients with Kawasaki Disease, this calculator will return a z-score for the left main coronary artery (LMCA), left anterior descending (LAD), and right main coronary artery (RCA).

Site Measurement Mean Range Z-Score


Coronary artery involvement in children with Kawasaki disease: risk factors from analysis of serial normalized measurements. McCrindle BW, Li JS, Minich LL, Colan SD, Atz AM, Takahashi M, Vetter VL, Gersony WM, Mitchell PD, Newburger JW; Pediatric Heart Network Investigators. Circulation. 2007 Jul 10;116(2):174-9.

Pevious Comments

On Wednesday Sep 12 2007, Master said:

Well done grasshopper. Listen for the sound of one hand clapping.

On Friday Dec 21 2007, Dr P K Tiwary said:

Excellent job!! Many thanks. Keep it up.

On Monday Jan 28 2008, Dr Aniruddha De said:

Can Z score be calculated offline? Please let me know how?

On Monday Jan 28 2008, Dan said:

>>Can the equations be calculated offline? Sure! >>how? From the McCrindle article in Circulation: "The predicted value for a patient of a given body surface area can be obtained by solving the first exponential regression equation, and the associated SD of that predicted value can be obtained by solving the second linear regression equation. The z score is obtained by dividing the difference between the actual measurement and the predicted measurement by the SD" -- the equations are printed in the journal

On Wednesday Apr 09 2008, REJANE DILLENBURG said:

it would be helpful to have the option of using only BSA, some kids don't get their height measured every time, and estimated BSA can be calculated by weight only

On Thursday Apr 10 2008, Dan said:

REJANE: the calculator works that way already- if height is not entered the BSA will be estimated from weight alone using this formula: 0.1 * (WT 0.67) Cheers!

On Tuesday Apr 22 2008, Al said:

very helpful, thanks!

On Tuesday Apr 22 2008, John said:

why not circumflex?

On Tuesday Apr 22 2008, Dan said:

@Al: you're welcome! @John: I obviously can't speak for the authors of these articles, but based on my own experience I could venture a guess: the circumflex coronary artery is difficult to image (by echo) with any reliability.

On Saturday May 24 2008, Neill Videlefsky said:

Thank you so much for this valuable information.

On Sunday May 25 2008, bleb said:

By adding or removing Weight, the Z-score jumps within a wide range. It is iportant to see the origine of the calculated Z-score once calculated (i.e., reference ACTUALLY used next to the calculated Z-score). Fianlly, I have tried to use the Z-score from McCrindle, I found it very complex (not user friendly at all) and very likely imbedded with errors (compared to 3 formulae calculations, including one derived from our databse). What do you think of McCrindles equation? Erroneous or adequate?

On Sunday May 25 2008, Dan said:

@Neill: You are quite welcome. @bleb: The WEIGHT is a required component of the BSA calculation- removing it forces the BSA == zero and, you are quite right, causes the z-scores to become quite unbelievable. I probably should have made the calculator handle this situation differently- in the meantime, ALWAYS include a weight. Regarding the complexity and possible errors of the McCrindle equations: I have encountered no such problems. Can you provide a specific example of how the calculations performed might be erroneous? I have tried hard to simply facilitate the calculation of z-scores from published literature without injecting my personal bias about the utility or suitability of the calculations for their purpose. However, since you asked: I find the McCrindle equations to be more than adequate: I think they are excellent- indeed, their published equations are the very model for how to calculate a z-score correctly.

On Monday May 26 2008, bleb said:

indeed no error in McCrindles CA equations, but a pitfall... that is, measured CA should be entered in CENTIMETERS (quite bizarre for such a cute little vessel)!, or else (I adjusted the formula to read my mm-CA in my XLS spreadsheet, but after a rest I HAD to take).

On Monday May 26 2008, Dan said:

I'm glad you got it figured out!

On Wednesday Jun 11 2008, R BADER said:

excellent effort ,need to post your resources if possible (references)

On Wednesday Jun 11 2008, Dan said:

R: "this calculator will return a z-score for the left main coronary artery (LMCA), left anterior descending (LAD), and right main coronary artery (RCA) as described by de Zorzi et al. (1998). The body surface area is calculated as described by Haycock et al. (1978). UPDATE (21 July 2007): The regression equations of McCrindle et al. (2007) have been added." What other resources/references do you need?

On Thursday Jun 19 2008, Samira Saady Morhy said:

Congratulations for this wonderful and helpful site!! The range for coronary arteries diameters in the de Zorzi et al. study (that is use in this site) are greater than those found in the study done by Tan et al. (Pediatric Cardiology 24:238-335,2003). In this study 390 health children were evaluated by echo. Why do you prefer the diameters described by de Zorzi and coworkers? Don’t you think that Tan and colleagues studied a greater number of children in echo machines with a better resolution? Warmst regards, Samira S Morhy, MD, PhD, FASE Hospital Israelita Albert Einstein Echocardiography Laboratory Sao Paulo, Brazil

On Thursday Jun 19 2008, Dan said:

The default coronary artery z-score reference is the McCrindle/Circulation 2007 article, actually. I prefer THAT reference over the Tan/Pediatric Cardiology 2003 reference because 1) it is more recent and, 2) it is more sophisticated in the manner in which the standard deviation is dealt with: The 2007 Circulation equations allow for nonconstant variance, whereas the 2003 Ped. Card. equations do NOT. I do like how they made up a new word for the Pediatric Cardiology article's title though: "Coronary normograms and the coronary-aorta index: objective determinants of coronary artery dilatation."

On Thursday Jun 19 2008, Ramesh Parmar said:

The Z scores were never these handy before. The site is very easy to use and information it gives is very reliable and helpful. An intelligent and beautiful piece of work!

On Tuesday Jul 15 2008, J J Shah said:

Excellent work. Should be part of the standard pediatric echo report.

On Tuesday Jul 15 2008, Dan said:

@ Dr. Shah: My thoughts, exactly. Thanks for the kind words!

On Wednesday Jul 30 2008, Rabih Hamzeh said:

This is great Dan.