You may want to check out this website
The Herb Place that has a natural program for eliminating heartworm. We have a dog that has just been diagnosed with heartworm and since the Vets in Japan won't do treatment (they say he is too old and the risk is too high), we see this as our only alternative at the moment (if we don't, he will die of the heartworm anyway).
The first response came back very quickly and we are still in the process of working out a treatment. I will let you know how it goes as the steps continue.