When Does a Slow Heart Rate Call for a Pacemaker?

A slow heart rate calls for a pacemaker when the slow rhythm comes from the heart's own electrical system, causes symptoms such as fainting, near-fainting, severe fatigue or shortness of breath, and does not have a reversible cause like a medicine. The number alone usually does not decide it. This article explains what a slow heart rate can be, how clinicians evaluate it, when a pacemaker is considered, and which symptoms need emergency care.

What a slow heart rate is, and when it is a problem

A slow heart rate is called bradycardia. Many healthy people, including athletes and some people during sleep, have slow heart rates and feel fine. A slow rate becomes a medical problem when the heart cannot pump enough blood to meet the body's needs, so the brain, muscles or lungs run short.

MedlinePlus describes an arrhythmia as a problem with the rate or rhythm of the heartbeat, including beats that are too slow. Whether a slow rhythm needs treatment depends mostly on symptoms and on what is causing it, not on one number on a watch or blood pressure cuff.

Symptoms that make clinicians take a slow rhythm seriously

A slow heart rate may cause symptoms that are easy to blame on aging. Tell your clinician if you notice any of these:

• Fainting or nearly fainting
• Lightheadedness or dizziness, especially on standing or walking
• Unusual tiredness or low stamina for daily tasks
• Shortness of breath with ordinary activity
• Chest discomfort
• Confusion or trouble concentrating

Fainting has many possible causes beyond the heart. Our article on fainting in an older adult covers that wider picture, so this page focuses on the slow-rhythm side.

Why the heart slows down

Several factors can contribute, and more than one may be present at once.

Problems in the heart's electrical system

The heartbeat starts in a small group of cells called the sinus node and travels through the atrioventricular (AV) node to the lower chambers. Age-related changes, scarring, and other heart disease can weaken the sinus node (sometimes called sick sinus syndrome) or block signals at the AV node (heart block). In heart block, the upper chambers may fire normally while signals reach the lower chambers slowly, intermittently or not at all.

Medicines

Beta blockers, some calcium channel blockers (such as diltiazem and verapamil), digoxin and certain antiarrhythmic drugs (such as amiodarone) can slow the heart. Combinations of several medicines can add up, which is one reason a full medication review matters. Digoxin in particular can build up in the body, and signs of too much can include nausea, vision changes and a slow pulse. If you started or increased one of these medicines and your pulse is much slower, or you feel dizzy or faint, call your prescriber or pharmacist the same day. Do not stop or change doses on your own, because stopping some heart medicines suddenly can cause harm. Our article on polypharmacy in older adults explains the wider medication issue.

Other medical conditions

An underactive thyroid, imbalances in potassium or other blood salts, sleep apnea, and infections can slow the heart or its conduction. Heart attack and other forms of coronary artery disease, which MedlinePlus describes as narrowing of the arteries that supply the heart, can damage the conduction system. Heart surgery, including valve surgery, can sometimes injure it too, and a meta-analysis of tricuspid valve surgeries examined how often a permanent pacemaker was needed afterward. Endocarditis, an infection of the heart's inner lining, and Chagas disease are less common causes in the United States, though they can affect conduction.

How clinicians decide whether a slow heart rate needs a pacemaker

Clinicians combine history, examination and testing. No single test settles it.

• Symptom and medicine history: when symptoms happen, what you were doing, and every prescription, over-the-counter product and supplement you take.
• Electrocardiogram (ECG): a brief recording of the heart's electrical activity that can show sinus node problems or heart block.
• Ambulatory monitors: a wearable recorder, worn for days to weeks or implanted under the skin, helps catch a slow rhythm that comes and goes.
• Exercise testing: checks whether the heart rate rises appropriately with activity.
• Blood tests: look for thyroid problems and electrolyte imbalances.
• Echocardiogram: an ultrasound of the heart that looks at structure and pumping strength.
• Sleep evaluation: considered if sleep apnea is suspected.

When a pacemaker is usually considered

Cardiology guidelines generally link pacemaker implantation to a slow rhythm that is connected to symptoms and has no reversible cause. Situations in which a pacemaker is commonly discussed include:

• Symptomatic sick sinus syndrome, where a slow rate or long pauses are tied to fainting, near-fainting or fatigue.
• Advanced or complete heart block, where signals between the upper and lower chambers are largely interrupted. This pattern can be serious even when symptoms are mild, so cardiologists often consider it more urgently.
• A slow rhythm that is needed treatment from a necessary medicine. If a heart medicine is important and cannot be changed, a pacemaker may allow it to be continued.
• Slow rhythms after heart surgery or a procedure, when conduction does not recover.

A pacemaker is often not recommended when the slow rate has a treatable cause, such as a medicine, an underactive thyroid or an electrolyte problem, and when it comes without symptoms. Your cardiologist will weigh these factors for you, and specific recommendations come from guidelines that specialists apply case by case.

What a pacemaker is and what the procedure involves

MedlinePlus describes a pacemaker as a small device placed under the skin of the chest that senses the heartbeat and sends gentle electrical pulses when the heart is too slow. It usually has a generator and thin wires (leads) that reach the heart through a vein. Some newer devices are small and sit inside the heart without leads in the chest pocket.

Implantation is typically done under local anesthetic with sedation, and many people go home the same day or the next day, though this varies. Some pacing approaches stimulate the heart's natural conduction pathway more closely, and researchers continue to study how these compare with conventional pacing.

Possible risks

Complications are not common but can occur. They include bleeding or bruising at the site, infection of the pocket or leads, a collapsed lung, and a lead that moves or needs adjustment. Tell your clinician about fever, redness, swelling or drainage near the device, because device infections need prompt evaluation.

Living with a pacemaker

Most people return to ordinary activities. You will have regular device checks, often including remote monitoring from home, so the team can follow battery life and settings. Your care team will give instructions about arm movement right after implantation, driving, and electromagnetic exposure such as certain medical scans. Ask them which activities and devices apply to your model.

A pacemaker treats a slow rhythm. It does not treat other heart conditions. People with heart failure or other heart disease still need ongoing care, and researchers are studying how often heart failure with preserved ejection fraction goes unrecognized in people who have pacemakers. For some people with weakened pumping function, a different pacing approach called cardiac resynchronization therapy may be discussed. Our article on heart failure stages describes that condition in daily life.

Questions to bring to your appointment

• Could any of my medicines be slowing my heart, and is it appropriate to adjust them?
• What did my ECG or monitor show, and do my symptoms line up with it?
• Has my thyroid and blood salt level been checked?
• What type of block or sinus node problem do I have?
• If a pacemaker is suggested, what type, and what alternatives exist?

When to Seek Medical Care