Homing in on Blood Pressure Monitoring

If you take blood pressure medication or have a history of high or low blood pressure, monitoring your BP at home can be an important way to track your heart’s health and prevent blood pressure-related emergencies such as heart attack or stroke, say two noted UT Southwestern cardiologists.

Because blood pressure can be highly variable, bringing your doctor a sample of your BP readings between visits can provide a better overall picture of your health. The following tips can help you understand your blood pressure, monitor it regularly, and take control of your health status and treatment.

Know your recommended range

It’s important to know your recommended blood pressure levels and see your physician if the readings are consistently high. Normal blood pressure is typically less than 120 for systolic (the number when your heart is contracting) and less than 80 for diastolic (when your heart is relaxed). A systolic measurement of 120-139 and a diastolic of 80-89 are considered prehypertension. Above 140/90 is hypertension, or abnormally high blood pressure.

Arm yourself with two BP readings

When taking blood pressure at home, at least two consecutive measurements should be taken one minute apart in the same arm. If the first two readings are quite different, additional measurements should be taken to get accurate results.

Blood pressure should be recorded twice daily, ideally in the morning (between 6 a.m. and noon) and evening (6 p.m. to midnight). Within these windows, try to be consistent and take your BP readings at the same time of day, when you are relaxed. 

BP readings in one arm should be compared to the other arm occasionally. If the average systolic number – the higher number – varies by more than 10 points between the two arms, it could be an indicator that you are at risk of heart disease, says Wanpen Vongpatanasin, M.D., a Professor of Internal Medicine at UT Southwestern and a specialist in BP research.

Several studies in recent years have shown that variations in BP readings on the right and left arm are associated with increased risk of death from heart attack or stroke, Dr. Vongpatanasin notes.

“While small differences from one arm to the other are normal, larger differences suggest that cholesterol-based plaque has built up in the arteries that supply blood to the arm with the higher reading and is likely to be building up in the arteries that supply the heart, as well. Narrowing of the arteries that supply blood to the heart muscle leads to heart attacks,” Dr. Vongpatanasin says.

If you do find a large difference between readings taken from one arm to the other, consider making an appointment with a preventative cardiologist.

Counter the ‘white coat’ effect

UT Southwestern Internal Medicine Professor Sharon Reimold, M.D., notes further that keeping track of your BP readings at home can also help mitigate what’s known as “white coat syndrome” – a spike in readings that comes from the fear or stress of simply being in a doctor’s office.

“People who take blood pressure medicines often are nervous about what their blood pressure will be when they’re seeing their physician, and that anxiety actually causes their blood pressure to rise,” Dr. Reimold explains. The “white coat” spike is particularly common among the elderly.

Taking your blood pressure at home, in familiar surroundings, can counter this effect and provide a more realistic reading of your BP during day-to-day life.

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