When Your Pulse Is Out of Normal Range

When taking their pulse, most people think of their heart rate — how fast their heart beats per minute, usually between 60 and 100 times. But your pulse strength, whether weak or bounding, can indicate a wide variety of health issues.

A weak pulse may indicate low blood pressure, heart disease or a blood vessel blockage, according to cardiologist Randall M. Zusman, MD, director of the division of hypertension at Massachusetts General Hospital and an associate professor at Harvard Medical School, both in Boston. "It could be someone who has low blood pressure – lower is better when we think about blood pressure, as long as the person isn't light-headed or dizzy."

On the other hand, if someone is light-headed and has a weak pulse, dehydration may be to blame, which can be worsened if they're taking medicine to lower blood pressure. If you're experiencing this, Dr. Zusman suggests drinking some fluids and seeing if the symptoms fade. If not or if you faint or feel faint, get medical attention.

Cardiac problems, such as atherosclerosis (plaque deposits made of cholesterol and other substances that accumulate inside blood vessel walls), aortic stenosis (the narrowing of the major artery leaving the heart) or a rapid or irregular heartbeat (arrhythmia) could also contribute to a weak pulse, Dr. Zusman says.

"People think of the heart as pumping out, but it also fills up between beats," he explains. "If your heart rate is very rapid, the filling time is very short. … Your pulse might be weak."

If your pulse is irregular, an electrocardiogram will be needed to diagnose the underlying cause of the arrhythmia, Dr. Zusman adds. Arrhythmias can be an emergency situation or harmless, according to the American Heart Association, making it important to get it checked out.

A weak pulse found only in one part of the body suggests blood vessel blockage. The weak pulse in one leg or arm can be compared with the pulse in the corresponding body part on the opposite side, Dr. Zusman says. In this case, according to the National Heart, Lung and Blood Institute (NHLBI), the explanation could be atherosclerosis, a narrowing of the arteries caused by the buildup of plaque.

Narrowed arteries in the heart can cause pain — known as angina — and arrhythmias. In the neck's carotid arteries, too much plaque can starve the brain, leading to stroke symptoms of weakness and paralysis on one side, says NHLBI.

Atherosclerosis can give rise to pain and numbness in the arms and legs and make the kidneys slowly fail. Clots can grow on the arterial plaques, break off and float through the bloodstream to the brain, causing a stroke, explains NHLBI, or to the heart, resulting in a heart attack, the institute says.

It's important to point out that there are many other reasons for low blood pressure or blood volume, from an allergic reaction to substantial blood loss or heart failure — any of which could be the problem behind a weak pulse.

Read more: About High Blood Pressure and Low Pulse

The opposite of a weak pulse is a bounding pulse, familiar as the strong beat felt during hard exertion. It should not appear suddenly for no apparent reason, nor should it persist after resting from exercise. "A bounding pulse – sort of a super strong pulse — could be an indicator of high blood pressure or a problem with a (heart) valve," says Dr. Zusman.

As confusing as it sounds, a bounding pulse and rapid heart rate can also be caused by arrhythmias or heart disease as well as by anemia, kidney disease, fever, pregnancy, anxiety and an overactive thyroid (hyperthyroidism), according to the Pennsylvania State University Milton S. Hershey Medical Center.

If you have a weak or a bounding pulse, talk to your doctor, Dr. Zusman says. He or she will consider your pulse, blood pressure and symptoms to determine what tests are needed to uncover the reason for your irregular pulse.

Read more: When Your Hear Beats Fast and Your Blood Pressure Rises: What to Know