http://en.wikipedia.org/wiki/Hericium_erinaceus
Consider lion's mane mushroom in supplement form.
Your diastolic is particularly troubling to me here- that means your heart is not relaxing as it should in between beats, which can in the long run, lead to a stiffening. Did the doctor order an echocardiogram? Is the doctor agreeable with you trying natural methods first to try to reduce your blood pressure?
You might check with a licensed Chinese acupuncturist/herbalist. I think acupuncture can help to lower blood pressure, though not sure about all particulars & they would be familiar with what herbs might help or not.
Exercise, weight loss if not at ideal weight (which can lessen the stress on one's heart), and practicing deep breathing a number of times a day for several minutes may all help to reduce blood pressure.