Hopefully your pup is just fine but definitely get the opinion of a specialist.
My daughters maltese "Daisy" went to her regular vet last monday and the vet heard a murmur and did an exray which showed her heart enlarged. The vet said to take Daisy to a cardiologist in Vienna, VA (northern VA) where she was diagnosed with a very rare heart condition called Eisenmenger syndrome. Prognosis was not very good - 6 mos to 2 years. Daisy is on several different meds (viagra, baby aspirin and an ace inhibitor).
Her regular vet contacted the doctors at Virginia Tech and discussed the case with them. And they felt that since Daisy is asymptomatic, she could lead a normal and long life with the medication but needs to be monitored every three months (bloodwork and checkup).
Your vet should be able to give you the names of cardiologists in your area. If not, I'd be happy to get the name and number of the vet in Northern VA. But also VAtech has a joint vet program with the university of MD. Maybe the vets at University of MD could see Reese? Their fees are probably less than the specialist (the cardiologist in NoVA charged 400.00).
VMRCVM - Doctor of Veterinary Medicine (DVM) Program
Sending Prayers that Reese is just fine!