My guess is that high blood pressure in and of itself should not be a problem for diving unless it is extremely high where it can suddenly cause a stroke or if you prone to something like malignant hypertension where your blood pressure can go up very high and fast and can cause seizure.
generally speaking, if you have essential hypertention (ie high blood pressure that is not a result of some other disease such as tumor in your adrenal gland, blockages in your blood vessels in your kidney or some other hormonal imbalance etc) which is by far the most common type, if it is relatively well control, it should not post any extra problem. Blood, like water, is non compressible so your blood pressure should not go up by increasing pressure alone.
However your blood pressure will go up with exertion. Make sure you have good exercise tolerance, as mentioned in earlier post, some medication may give you less exercise tolerance, some may make you more dizzy. Some people are very sensitive to salt and make blood pressure go up, you are sure to get extra salt while diving.
I think if you talk to your MD about ability to exercise, limitation on physical activity, exertions etc, that should give you pretty good idea of what you can or cannot do.
