Tachycardia vs. Bradycardia

Tachycardia and bradycardia are two medical terms that sound similar, but what do they actually mean? And what’s the difference between them?

“Tachycardia and bradycardia describe heart rate — how many times per minute your heart beats, or how fast or slow your heart beats,” explains Jane Henoch, FNP-BC, a Mass General Brigham nurse practitioner. “With tachycardia, your heart beats faster than expected. With bradycardia, your heartbeat is slower than what is considered normal. Normal heart rates are generally between 60 and 100 beats per minute.”

Henoch, who cares for patients at Massachusetts General Hospital, notes that a heartbeat that is faster or slower than normal isn’t always cause for concern. However, there are certain signs of more serious medical conditions to watch out for. She explains the differences between tachycardia and bradycardia, as well as how to know when to seek treatment.

Bradycardia vs. tachycardia: What’s the difference?

Bradycardia and tachycardia are two different types of irregular heartbeat. With bradycardia, your heart beats too slow, and with tachycardia, it beats too fast.

Bradycardia and tachycardia can signal a problem, but not everyone’s heart rate falls within the “normal” range.

Checking your heart rate with a device, or manually with your fingers on the radial pulse beneath your thumb on your wrist, tells you how many times your heart beats per minute. To know your resting heart rate, check it when you’re sitting or lying down, feeling calm, aren’t sick, and haven’t just finished exercising.

The average resting heart rate is 60 to 100 beats per minute. If your heart rate falls outside of the average, you may have:

• Bradycardia, where your resting heart rate is slow — usually less than 60 beats per minute.
• Tachycardia, where your resting heart rate is fast — more than 100 beats per minute.

Tachycardia: Why is my heart beating so fast?

There are many reasons why you may experience tachycardia. Your heart rate can increase for very common reasons, such as:

• Physical activity
• Anxiety or stress
• Pain or fear
• Fever
• Certain medications or illicit drugs

However, there are underlying health issues that may cause your heart to beat fast even at rest. Some health issues that can contribute to tachycardia include:

• High blood pressure (hypertension)
• Heart disease
• Heart failure
• Hyperthyroidism (when thyroid glands overperform)
• Lung disease
• Anemia
• Infection

There are different types of tachycardia: some are mild, and others are more severe. A rapid heart rate can prevent your heart from properly filling with blood between each beat. This becomes dangerous if your heart can’t supply your vital organs with enough oxygen or can’t send enough blood throughout your body.

Bradycardia: Why do I have a low resting heart rate?

There are many possible reasons why your heart beats slow. Certain people are more likely to have a slower resting heart rate, like athletes, physically active adults, and elderly adults.

Your heartbeat may be slower due to:

• Medications
• Chemical imbalances
• Problems with your heart, like congenital heart defects, complications from heart surgery, or damage to the heart tissue from aging
• Hypothyroidism (when thyroid glands underperform)
• Inflammatory diseases like myocarditis (when your heart tissue is inflamed) or lupus
• Problems with breathing during sleep (obstructive sleep apnea)

A low heart rate doesn’t always cause symptoms, and you may not need any treatment. It depends on different health factors and how severe your bradycardia is.

A slow heartbeat prevents the heart from pumping blood fast enough. In some cases, the organs in your body don’t receive enough oxygen. This can cause more worrisome symptoms like feeling faint, disoriented, or feeling tired after doing minor tasks. These are the kind of symptoms that would warrant a visit to your primary care or other provider.

What is tachy brady syndrome?

Tachycardia and bradycardia are two different conditions, and most people experience one or the other at different times. However, tachy brady syndrome is a condition with your heart alternates between beating too fast and beating too slow.

Tachy brady or sick sinus syndrome affects the sinoatrial node in the heart — commonly called your heart’s “natural pacemaker.” With this condition, the heart rate can go from elevated rates to slower ones. Sometimes medication can help to slow the fast heart rate down, but the only way to manage a slow heart rate is with a pacemaker.

When to worry about a fast or slow heartbeat

If your heart is beating too fast or slow, how do you know when to worry?

“If your heart temporarily beats too fast or too slow, it isn’t necessarily a sign of a medical condition,” Henoch says. “Different factors like temperature, emotions, exercise, and medications can affect your heart rate. But if it’s associated with symptoms like shortness of breath, lightheadedness, feeling faint or actually fainting, or you notice it happens at rest several times a day or week, tell your provider.”

Call your health care provider if you notice your resting heart rate is sometimes faster or slower than normal, whether it’s several times per day or per week. You should also tell them if it lasts longer than an hour.

Seek immediate medical attention if you experience:

• Chest pain
• Fainting
• Shortness of breath
• Dizziness or lightheadedness

Your irregular heartbeat may also be more concerning if you have one or more of these risk factors:

• Cardiomyopathy, meaning damage to the heart muscle (which can be from previous heart attack, congenital heart disease, a virus, or other causes)
• Congenital heart disease
• Coronary artery disease
• Genetic heart disease
• History of substance use disorder or smoking
• Obesity
• Sleep apnea

Henoch encourages people to tell their primary care provider if they’re worried about their heartbeat, especially if they have any of the above risk factors. They may refer you to a cardiologist. “It’s always better to let us know, so that you can be properly evaluated.”

Lifestyle changes to manage tachycardia and bradycardia

Some cases of tachycardia or bradycardia require medical treatment, depending on the cause and severity. You should always follow the treatment plan your doctor prescribes for your unique situation.

But there are small changes you can make in your daily life to help manage a fast or slow heartbeat and reduce symptoms. If you’re living with tachycardia or bradycardia, consider these heart-healthy lifestyle changes:

• Eat a healthy diet. Making a heart-healthy grocery list helps you prep meals that are low in sodium and filled with nutrients that keep your body and heart healthy.
• Avoid tobacco products. Smoking can make existing heart conditions worse — get tips to quit smoking.
• Get regular exercise. This benefits your heart muscles and improves its function over time. You can try walking or strength training.
• Limit or avoid alcohol.
• Limit caffeine intake.
• Maintain a healthy weight. Having overweight or obesity can make your heart work harder. Talk to your provider about healthy ways to manage your weight.
• Manage stress levels through relaxation or breathing techniques, like meditation.
• Manage high blood pressure and high cholesterol.

If you notice your heart beats slower or faster than usual, Henoch encourages talking to your health care provider. “It’s important to pay attention to your body—especially when it comes to your heart,” she says. “We’ll help you figure out what’s going on and work with you to manage it.”