Many heart murmurs are not serious. The Doppler will show which valves the heart murmers are coming from and how significant they are. A heart murmur is usually caused by a leaky valve or a septal defect. The valves open and shut to allow blood to enter and exit chambers of the heart. The septum is in the center of the heart and separates the atria and the ventricals. If a valve does not shut tightly enough after the chamber has released blood into the next chamber, the blood will leak back into the empty chamber and cause a murmur, which is a sound. If there is a hole in the septal wall, blood can be transferring back and forth between chambers, when it would normally not be. This can cause a murmur as well.
The doppler is the perfect test for a murmur, to see if it is anything to be concerned about. In many cases, the leak is not significant enough to warrant any treatment, and will be followed annually. I hope this is where you Aunt falls on the spectrum.
If there is a significant leak, some can be treated with medication alone. I would not get too worried until you get the results of the doppler!
So you know - I was a Vascular and Echo(Heart) sonographer for 18 years and performed many Dopplers on people with murmurs.