As stated above, it has been my experience that the general long term affects of MJ will reduce blood high pressure issues due to stress and anxiety. I have also experienced a postiive affect on blood glucose , as I am a diabetic.
Of course, common sense tells us that we may occasionally experience high blood pressure / pulse rates due to the occasional paranoia caused by smokin a little too much, although this is temporary. And if da weed causes you to devour a large bag of chips and 2 large pizza's during munchie time ... that will have a negative affect on your cardiological system.