toddler with wpw.. how much should heart rate fluctuate while resting?

my toddler was diagnosed with wpw right after birth. she has not had any runs of svt for a long time but the other night she suddenly began shaking uncontrollably and was very mottled in colour (fingernails even dusky).  I took her to the hospital right away her heart rate was constantly bouncing from 145-188 and everything inbetween while she was just lying down. we are waiting for a cardiologist appt but just wondered how much fluctuation during rest is normal? it can't be normal to be at 144 ten jump to 176 then 155 all in a matter of seconds?

[CCFheartMD11]

A resting heart rate in the 140-180 range is certainly not normal, but not completely unexpected in the setting of WPW either.

The issue with WPW is that there is an accessory pathway between the upper chambers and lower chambers of the heart. Typically, there is only one connection between the two, and that is the AV node. In WPW, though, the extra pathway allows for extra communication between the top and bottom chambers, which provides an environment compatible with an SVT (supraventricular tachycardia).

Your daughter was likely in an SVT when all of this happened, which can cause the symptoms you were describing. The heart rate in SVT can be in the range of 150-200, sometimes even higher.

[cvv02]

also should note her oxyen sat was 93 and she has also been diagnosed with asthma since around 4 months old.. (she is 2 and weighs 31 pounds)