Sheepdog,
The complicated & elusive Z score is how the ped. docs measure the deterioration of our little one's heart conditions. Because kids (from newborns to teens!) come in a big range of weights & sizes, what is considered normal for their their cardiac structures/functions is highly dependent on their size, or body surface area (BSA). Once the BSA is calculated, the cards punch the info into a computer and come up with a range of expected "normal" values for all things cardiac. If a measurement is outside that normal expected range, the amount of standard deviations above the expected ranges is measured by Z-score. Thus the higher the Z-score, the worse the heart is. Hope this very basic explanation helps a bit!
