What’s a dangerous heart rate?

A racing heart can be scary.

Heart attack? Panic attack? The symptoms can be similar.

A fast-beating heart may be concerning or it could just be anxiety, which can come and go. Though it can vary from person to person, a normal pulse or heart rate is between 60 and 100 beats per minute (BPM) taken when you’re not exercising, known as your resting heart rate.

Anything that causes increased stimulation, whether physical or emotional, could increase your heart rate. That includes caffeine and other herbal and medicinal stimulants.

Heart rhythm versus heart rate

Besides the rate of your heartbeat, your heart’s rhythm is another indicator of whether your heart is healthy. Your heart muscle contracts and relaxes in a certain pattern. It could be regular, irregular, fast or slow.

A health care provider can tell if your heart rhythm is regular by listening to your heart with a stethoscope or examining an electrocardiogram or EKG, a test used to evaluate the heart.

If your heart rhythm is regular and yet you have a fast heart beat — over 100 BPM — your high pulse rate likely isn’t heart-related. What’s driving your heart rate up could be dehydration, anxiety, fever, medications, anemia, sleep deprivation, an overactive thyroid or another issue.

However, if your heart rhythm is irregular, the question of whether you need to be concerned depends on what’s causing it. Atrial fibrillation, atrial flutter and supraventricular tachycardia are all types of heart disease in which the heart beats faster than normal or at an erratic pace. Left untreated, these conditions could lead to heart failure.

When is a pulse too slow?

Instead of a consistently fast heart rate, say yours is often under 60 beats per minute. That, too, can be caused by several different factors. Medications, sleep apnea, fitness level, an underactive thyroid, hypothermia, anorexia or a disorder affecting how electrical impulses travel through your heart are some of the causes of a slow heart rate.

If you have other symptoms along with a slow heart rate such as dizziness, fainting, fatigue, confusion or shortness of breath, see your health care provider.

Well-conditioned athletes often have a low resting heart rate of 40 to 50 beats per minute. This is because exercise strengthens the heart muscle, allowing it to pump more blood with each heartbeat, so the heart beats fewer times per minute. Older individuals also sometimes have a heart rate under 60 BPM. Regardless of age, it’s also normal for someone’s heart rate to dip lower than usual during sleep.

Even more important than your heart’s rate is its rhythm. You can have a heart rate in the 30s or in the 120s, but if your heart rhythm is normal, that may not be dangerous.

Your pulse may even be normal and yet you have a dangerous heart rhythm, also called arrhythmia.

Expert Guide to Heart Health: Answers to more of your heart health questions

Know your heart rate

You can check whether your pulse is normal by taking it yourself, putting your pointer and middle fingers on the inside of your opposite wrist just below the thumb. When you feel a pulse, count the number of beats you feel in 15 seconds then multiply the number you get by four to get the number of beats per minute.

Another way to find out your heart rate is with a device such as a blood pressure monitor or pulse oximeter, which measures the oxygen level in your blood.

Checking your heart rhythm

Several devices can be used to find your heart’s rhythm:

• An EKG is a painless test that can be done in the office and gives a quick snapshot of heart rhythm at that time. Electrodes are placed on your chest, arms and legs to record the activity. The test takes just about 10 minutes.
• A Holter monitor is a small device you wear that records a continuous ECG, usually for 24 to 48 hours.
• A cardiac event monitor is similar to a Holter monitor but can be worn for up to 30 days.
• Devices such as loop recorders can be implanted under the skin to monitor your heart rhythm for up to 3 years.

When should you see a doctor about your heart rate?

You may want to start with a visit to your health care provider if your heart rate is consistently above 100 beats per minute or below 60 beats per minute (and you’re not an athlete), or if you’re also experiencing shortness of breath, fainting spells, lightheadedness or feeling fluttering or palpitations in your chest. It may be nothing to worry about, or it could be something that needs to be treated.