CHD's and heat exhaustion

My daughter is 7yr s/p CHD (ASD,VSD,PDA,pulmonary stenosis, aortic stenosis, and DORV).  She has had an EKG every year since, and Echo every other year. She is on no meds, other than the rare occasion OTC for allergies or ibup.  This last April being the last visit to her peds card.  She has had a stress test 1 yr ago and every time all tests, vitals, etc are WNL. She is approx 85lbs, and is approx 4' 6". Her complaint for the last year has been dizzyness, lightheadedness, and occasionally rapid heart rate all occurring during her sports activities.  She plays outdoor soccer and cheers competitively. She only seems to complain with elevated temperatures.  The gym is not air conditioned. My question then really becomes is she susceptible to heat exhaustion becasue of her heart?  Is there something else we should be doing or watching for?  We hydrate her before practices and during.  Make sure she eats a light meal with carbs and protein.  Are there other tests that should be done?  Thank you.

[Cleveland Clinic]

I am not a pediatric cardiologist and cannot comment on this issue. May I suggest you contact her pediatric cardiologist which has been following these findings all along?