absolutely none. the "energy" in these drinks increases blood pressure and heart rate. they are not safe for anyone, let alone a 13 with heart problems. however, red apples contain more energy than a cup of strong coffee, without the terrible side effects.
You're thinking about putting nitro into a Geo. Why would you bother to ask folks on ask? The majority of folks here aren't MDs. Tomorrow give your MD a call & get an expert opinion, that's why he / she make the big $.