Gage Martindale, who is 8 years old, has been taking a blood-pressure drug since he was a toddler. "I want to be healthy, and I don't want things in my heart to go wrong," he says.

And, of course, his mom is always there to check Gage's blood pressure regularly with a home monitor, and to make sure the second-grader doesn't skip a dose of his once-a-day enalapril.

These...