Heart Health
High blood pressure / hypertension

Using Home Blood-Pressure Monitors

For most people, a visit to a health care provider typically starts with a gentle squeeze—the sensation of a blood pressure cuff inflating around their upper arm. But a single blood pressure reading offers only a glimpse into the health of that person’s cardiovascular system, according to the Harvard Heart Letter.

“When you have your blood pressure checked in the doctor’s office, you’re in an artificial environment that is not reflective of the vast majority of the time when your blood pressure is going through its daily excursions,” says cardiologist Dr. Elliott Antman, professor of medicine at Harvard Medical School. Throughout the course of a day, the average person’s systolic blood pressure (the first number in the reading) may fluctuate considerably.

Some people get very anxious in medical settings, which can cause their blood pressure to rise—a phenomenon known as white-coat hypertension. Others may feel like they’re in a protected, safe place where they can sit back and relax, which may cause their blood pressure to be lower than normal. If their blood pressure is high at other times, however, they may have a condition called masked hypertension.

The U.S. Preventive Services Task Force, a federally sponsored group that draws up medical guidelines, recommends that people measure their blood pressure outside of the medical setting to confirm a diagnosis of high blood pressure before starting treatment.

This is called “ambulatory blood pressure monitoring.” For 24 hours, a patient wears wear a small portable machine on a belt or a pouch connected to a blood pressure cuff on the arm. The device records blood pressure every 15 to 30 minutes. Once the test is done, a patient’s physician downloads the results and analyzes.

But, the Harvard Health Letter says, ambulatory blood pressure monitoring is generally offered only in specialized blood pressure clinics. The testing costs about $200 but isn’t always fully reimbursed by insurance. And people sometimes find it hard to sleep when they’re wearing the device.

One good option is to use a home blood pressure monitor, and recent technological advances have made the process a lot simpler, Antman says. Many digital home blood pressure monitors include a cord that plugs into a smartphone. And two companies, Withings and iHealth, have FDA-approved blood pressure devices that can send readings to a smartphone wirelessly.

Current guidelines suggest that most people aim for a reading of 140/90 millimeters of mercury (mm Hg) or lower. But recent findings suggest that an even lower target (a systolic reading of less than 120 mm Hg) may prevent more cardiovascular complications and deaths.

The Harvard Heart Letter is available from Harvard Health Publications, the publishing division of Harvard Medical School, for $20 per year. Subscribe at www.health.harvard.edu/heart or by calling 877-649-9457 (toll-free).