Have you ever heard of Heart Rhythm Meditation? I have been practicing this technique for several years. It seems like you may be interested in lowering your blood pressure, stress levels, etc. I began studying this technique while looking for a routine to help manage stress, and of course for something to bring more harmony to my life.
To answer your question regarding HBP, yes it does. It not only lowers blood pressure, but also stabilizes your heart rhythm by lowering your heart rhythm variability HRV. BTW, I have even had my heart rate measured while meditating hooked up to a computer with a sensor just to see if that is really the case. It works.
It is really something else.
FYI, there is an amazing book by Puran Bair called Living From the Heart.
You can find out more about HRM over at http://appliedmeditation.org
Keep in touch, and let me know if you have any questions about this.
Not sure if you are referring to this $250 device by Resparate. It is a audio feedback method to lower breathing rate with claims that it can lower blood pressure. I have the device but haven't committed the time to comply with the required treatment protocol.