She'll inflate the cuff to a pressure higher than your systolic blood pressure, and it will tighten around your arm. Then she'll release it. As the cuff deflates, the first sound she hears through the stethoscope is the systolic blood pressure. It sounds like a whooshing noise. The point where this noise goes away marks the diastolic blood pressure.
"Blood pressure guidelines are not updated at regular intervals. Instead, they are changed when sufficient new evidence suggests the old ones weren't accurate or relevant anymore," says Dr. Paul Conlin, an endocrinologist with Harvard-affiliated VA Boston Healthcare System and Brigham and Women's Hospital. "The goal now with the new guidelines is to help people address high blood pressure — and the problems that may accompany it like heart attack and stroke — much earlier." 

If your blood pressure readings are consistently high, you and your doctor will probably discuss treatment strategies. Treatment for high blood pressure often begins with lifestyle changes such as a weight loss and exercise program as well as a low sodium diet. In fact, the AHA recommends adopting these strategies as a means of preventing the development of high blood pressure and heart disease. If these strategies are not successful in lowering your blood pressure, medications may be recommended.
Peter, I’ve been using a blood pressure meter for nearly 30 years, so my response is based on my personal experience and information I’ve acquired over the years. First, I suggest that you take your meter to the doctor and have them check several readings of your meter against theirs. For example, If your meter consistently shows it’s 10 points lower than the doctor’s, just delete the 10 points from your meter reading (have them check both numbers so you can adjust both as necessary). Also, it’s common that many doctor’s offices take your blood pressure incorrectly (you should actually sit still for 5 minutes, with your feet on the floor and the cuff at the same level as your heart) . Some of us have”white coat” hypertension, so you may always be elevated at the doctor’s office. If you are a large man, you (and your doctor’s office) may need to use a larger cuff as the wrong size of cuff can affect your reading. Also, I spoke with customer service at one of the companies that makes many of the home & professional meters, and she told me that the automated machines are not very accurate if you have kidney disease or heart failure (I have both). Ask the doctor’s staff to always use the manual system and it will be more accurate than those noisy automatic ones.
Typically, more attention is given to systolic blood pressure (the first number) as a major risk factor for cardiovascular disease for people over 50. In most people, systolic blood pressure rises steadily with age due to the increasing stiffness of large arteries, long-term buildup of plaque and an increased incidence of cardiac and vascular disease.