Hypertension Stage 1 is when blood pressure consistently ranges from 130-139 systolic or 80-89 mm Hg diastolic. At this stage of high blood pressure, doctors are likely to prescribe lifestyle changes and may consider adding blood pressure medication based on your risk of atherosclerotic cardiovascular disease (ASCVD), such as heart attack or stroke.
When your heart contracts and squeezes blood out into your network of arteries, the pressure inside those blood vessels is at its highest. This is called systolic pressure and it’s the top number on your blood pressure reading. In between beats, the heart relaxes and the pressure drops. This is your diastolic blood pressure, and it’s the reading’s bottom number.
Blood pressure refers to the force exerted by circulating blood on the walls of blood vessels and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as blood moves through arteries, arterioles, capillaries, and veins; the term blood pressure generally refers to arterial pressure, i.e., the pressure in the larger arteries, arteries being the blood vessels which take blood away from the heart. 

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.

The new guidelines note that blood pressure should be measured on a regular basis and encourage people to use home blood pressure monitors. Monitors can range from $40 to $100 on average, but your insurance may cover part or all of the cost. Measure your blood pressure a few times a week and see your doctor if you notice any significant changes. Here are some tips on how to choose and use a monitor.
I just started using high blood pressure medication and purchased a blood pressure meter at age 72. what concerns me is that the BP readings I get have a very wide variance in. I measure every morning as soon as I wake up, while still in bed and prior to having any coffee. I take 3 or 4 readings. I have found that on any given day my reading can vary from 126 to 143 systolic and the diastolic reading from 68 to 87. this wide variance makes it very difficult to track trends. My questions are: is this normal? is my instrument possibly defective? How can my cardiac doctor make a decision to put me on life long medication based on SINGLE reading in his office?