BiDil contains an Isosorbide dinitrate that dilates blood vessels. When blood vessels are dilated, it is easier for the heart to pump and oxygenated blood to heart cells. I take isosorbide prior to going to the gym for a workout. This prevents angina (chest pains) when exercising 3x a week with the greater demand for oxygen....It is recommended to take a break from the medication as continued use will cause one to tolerate the med without any benefit.
If the medication you are taking lowers your blood pressure, maintain normal heart rate and there is no chest pain (angina) it would appear you are properly treated and your medication is effective. You may not need continued medication with Bidil if you have stable angina (no chest pain with rest or minor activities)...unstable angina is chest pain with or without exertion and continue med would be appropiate.
I had congested heart failure (EF below 29%) about 7 years ago, enlarged left ventricle, high blood pressure, occluded coronary vessels. Medication that lower my blood pressure helped my heart to return to normal size when the reduced workload that burdened the heart. Also, my EF returned to normal and cureently at 59%.
Hope this helps and if you have any follow-up questions or comments you are welcome to respond. Thanks for sharing, take care.