The app works with the AliveCor device - a smartphone cover with two metal plates on the back.
The device can be used with the app to conduct an electrocardiogram, also known as an EKG, wirelessly, and then send it from that smartphone to the patient's doctor.
"It is so easy for them to upload that EKG and send it to me and just like they are sending it from their smartphone, I am reading on my smartphone," said Dr Jennifer Silva, a Washington University Pediatric Cardiologist at St Louis Children's Hospital.
There are 37 children in the study ranging in age from 2 months to 18 years old, 'fox2now.Com' reported.
The device, however, is not a substitute for a full EKG at a doctor's office because it only tests the heart's rhythm and rate.
The AliveCor has already been approved by the US Food and Drug Administration for use by adults.