Bradycardia is an abnormally slow heart rate. In adults, it is defined as a heart rate of less than 60 beats per minute. Different types of bradycardia include (collectively referred to as “bradyarrhythmias”) :
Sinus bradycardia—an unusually slow heartbeat due to heart disease, a reaction to medication, or normal causes (such as excellent fitness or deep relaxation)
Sick sinus syndrome—an unusually slow heartbeat due to a malfunction of the heart’s natural pacemaker (sinoatrial node)
Heart block (atrioventricular block or AV block)—an unusually slow heartbeat due to a slowing or blocking of electrical impulses in the heart’s conduction system
Some types of bradycardia produce no symptoms. Others may cause noticeable symptoms, such as:
Fainting or loss of consciousness (“syncope”)
Dizziness, sensation of light-headedness
Weakness
Mild fatigue
Sensation of your heart fluttering (palpitations)
Shortness of breath
Chest pain
Low blood pressure (hypotension)
Serious forms of bradycardia, such as complete heart block, are medical emergencies. They can lead to loss of consciousness or sudden
cardiac arrest.
Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam. In particular, the doctor will listen to your heart with a stethoscope.
Tests may include:
Blood tests—to look for certain abnormalities that may explain the bradycardia (eg, electrolytes, glucose, thyroid function, and drug levels)
Electrocardiogram
(ECG, EKG)—a test that records the heart’s activity by measuring electrical currents through the heart muscle.
Echocardiogram—a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart.
Holter monitor or event monitor—a portable, continuous heart rhythm monitor that you wear as you perform normal daily activities.
Exercise stress test—a test that records the heart’s electrical activity during increased physical activity.
Nuclear scanning—radioactive material is injected into a vein and observed as it is distributed through the heart muscle
to look for coronary artery disease.
Coronary angiography—x-rays taken after a dye is injected into the arteries; this allows the doctor to look for abnormalities in the coronary arteries of the heart.
Treatment
If no underlying heart disease is detected, the heart’s response to exercise is normal, and there are no symptoms of low cardiac output, treatment may not be required. Your doctor may choose to monitor your heart rate and rhythm periodically. People with cardiac symptoms and conditions usually receive treatment.
Treatment for symptomatic bradycardia may include:
Discontinuing any medications that slow the heart rate
Diagnosis and treatment of any underlying conditions
Intravenous (IV) atropine–this medication may be used to temporarily increase heart rate
Artificial pacemaker–this device may be either temporarily or permanently implanted under the skin in the chest wall. Whenever the heart rate drops too low, the pacemaker takes over the job of providing the electrical impulses needed to establish and maintain a normal heart rhythm.
Prevention
To help prevent bradycardia:
Treat underlying conditions that might lead to bradycardia.
Carefully follow your doctor’s directions when using medications (especially those that can potentially cause bradycardia).
Check with your physician or pharmacist before using any over-the-counter medication or natural supplement to assure that it will not interact with your other medications
Follow general advice for preventing the development of heart disease, including:
Maintain an appropriate weight.
Consult your doctor about a safe exercise program.
Stop smoking.
Eat a healthful diet, one that is low in saturated fat and rich in whole grains, fruits, and vegetables.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
