I am not being flip, but try the Internet. Put in the Cleveland Clinic, and the names of the University Hospitals. Then look under Pediatric Staff, or Cardiology Staff, and print out the relevant bio (as well as contact #'s) info for any of the Physcians that sound appealing to you.
Then, I would take my list of names to the Dr. that I most admired and trusted, who probably isn't even your son's pediatrician. This Physician would be someone on staff where you work, or someone that could consult via phone or e-mail, and ask if he/she knows any of these physicians. Someone may have gone to school with one of them-you never know.
At the very least, I would take my list to my son's Pediatrician, or the Pediatric Cardiologist in your town, if you wind up going there. I would also check to see if there were any Preferred Providers on your insurance, or any that your insurance would not pay for. With the assistance of these people, pick the Physician that you feel will best suit your son.
Of course, be sure to put your son's situation in the hands of The Great Physician. I will be thinking about you all, and praying for you both. God bless.