What is Considered a Slow Heart Rate? 10 Slow Heart Rate Causes

Slow heart rate symptoms

As people become increasingly health-conscious, it's more common to monitor vital signs at home, such as blood pressure and heart rate. Some people may have automated monitoring equipment or a smartwatch that detects heart rate. Others may only find out about an abnormality when they start to experience symptoms, or they visit a doctor's office. The heart is a vital organ that supplies the body with oxygenated blood, and if the heart is beating too slowly, the reduced blood supply can cause a number of symptoms that require investigation.

Common accompanying symptoms

You may also experience the following.

• Palpitations
• Dizziness
• Fainting
• Fatigue
• Chest pain
• Shortness of breath
• Reduced exercise tolerance

Slow heart rate causes and conditions

A slow heart rate, or bradycardia, is diagnosed when the heart beats less than 60 times per minute. However, having bradycardia doesn't always mean that there is an underlying medical problem requiring treatment. Your physician will be able to determine what kind of intervention is necessary after reviewing your symptoms and history. The following details may help you better understand what you're experiencing.

Normal (physiological) causes

Normal causes that can lead to a slower heart rate may include the following.

• Athletic conditioning: The heart is a muscle, so when it is well-trained through cardiovascular exercise, it does not need to pump as much to supply the body with oxygen. Thus, it is common for athletes to have slow resting heart rates in the 50s or even 40s.
• Youth: Young adults, especially young women, may have naturally low heart rates and blood pressures that do not need to be treated unless there are other symptoms.

Heart disease

Heart disease can lead to a slow heart rate in a variety of ways, described here.

• Congenital heart disease: In some cases, a slow heart rate can be a sign of a birth defect in the heart, especially if diagnosed at a young age.
• Adult heart disease: The heart's natural pacemaker causes the heart to contract by supplying an electrical current to the muscle cells. If this is not operating properly, the heart rate can slow as backup pacemakers take over but do not fire as frequently.
• Heart infection: Inflammation and infection of the heart, myocarditis or endocarditis, can interrupt the natural heart rhythm.
• Heart attack: This occurs when the blood vessels that supply the heart become blocked and part of the heart muscle is damaged. A heart attack may impact the heart rate, especially if the natural pacemaker is involved.
• Cardiac procedures: Certain procedures or surgeries to correct heart problems may injure the conduction system of the heart and cause it to contract too slowly.

Other medical causes

Other medical causes of a slow heart rate may include the following.

• Medications: Many prescription medications can slow the heart rate, especially beta blockers taken for high blood pressure, or medications for psychiatric disorders.
• Electrolyte derangements: The body depends on precise amounts of elements like potassium and calcium in the blood, and when these electrolytes are abnormal, the heart rate can slow.
• Hypothyroidism: Low amounts of thyroid hormone slow many body processes, including the heart rate.

This list does not constitute medical advice and may not accurately represent what you have.

Third degree atrioventricular nodal block

3rd degree atrioventricular nodal block is the most severe form of conduction blockage.

Rarity: Rare

Top Symptoms: shortness of breath, racing heart beat, tight, heavy, squeezing chest pain, lightheadedness, deep chest pain, behind the breast bone

Symptoms that never occur with third degree atrioventricular nodal block: swelling of one leg, swelling of one foot, swollen ankle

Urgency: Primary care doctor

Side-effect(s) of chemotherapy

Unfortunately, chemotherapy has many side-effects, ranging from hair loss to fatigue to nausea. This occurs because the treatment affects not only diseased cells but also healthy cells.

Rarity: Uncommon

Top Symptoms: fatigue, loss of appetite, arthralgias or myalgias, dizziness, sore throat

Symptoms that never occur with side-effect(s) of chemotherapy: headache resulting from a head injury

Urgency: Primary care doctor

Heart attack

Most heart attacks happen when a clot in the coronary artery blocks the supply of blood and oxygen to the heart. Often this leads to an irregular heartbeat - called an arrhythmia - that causes a severe decrease in the pumping function of the heart.

Rarity: Uncommon

Top Symptoms: chest pain, shortness of breath, tight, heavy, squeezing chest pain, being severely ill, nausea

Urgency: Emergency medical service

Hypothyroidism

Hypothyroidism, or "underactive thyroid," means that the thyroid gland in the neck does not produce enough of its hormones. This causes a slowing of the body's metabolism.

The condition can occur due to autoimmune disease; any surgery or radiation treatment to the thyroid gland; some medications; pregnancy; or consuming too much or too little iodine. It is often found among older women with a family history of the disease.

Common symptoms include fatigue, constantly feeling cold, weight gain, slow heart rate, and depression. If left untreated, these and other symptoms can worsen until they lead to very low blood pressure and body temperature, and even coma.

Diagnosis is made through a simple blood test.

Hypothyroidism is easily managed with daily oral medication. The patient usually starts feeling better after a couple of weeks and may even lose some extra weight. It's important for the patient to be monitored by a doctor and have routine blood testing so that the medication can be kept at the correct levels.

Rarity: Rare

Top Symptoms: fatigue, depressed mood, difficulty concentrating, weight gain, muscle aches

Urgency: Primary care doctor

Myocarditis

Myocarditis is an inflammation of the heart muscle, also called the myocardium.

It is a rare complication of any viral, bacterial, parasitic, or fungal infection. Reaction to drugs, medications, chemicals, or even radiation can bring about myocarditis.

Anyone with a weakened immune system or pre-existing heart condition is susceptible.

Symptoms include fatigue, chest pain, and shortness of breath, especially following a viral upper respiratory illness. Swelling of the feet and legs from poor circulation may be seen.

If symptoms are severe, take the patient to the emergency room or call 9-1-1. Myocarditis weakens the heart so that it cannot pump blood as it should. Blood clots, stroke, heart attack, abnormal heart rhythm (arrhythmia,) and sudden cardiac death can result without treatment.

Diagnosis is made by electrocardiogram (ECG,) chest x-ray, MRI, echocardiogram, and blood tests.

Short-term treatment is with rest and medication, depending on what kind of illness brought about the myocarditis. Sometimes, devices to support the heartbeat may be surgically implanted.

Long-term treatment may involve medicines such as ACE inhibitors, ARBs, beta blockers, and diuretics.

Rarity: Rare

Top Symptoms: fatigue, headache, shortness of breath, muscle aches, chest pain

Urgency: Hospital emergency room

Beriberi (adult)

A low level of vitamin B1 (thiamin) can cause damage to the heart, brain and nerves. This can result in symptoms like weakness, amnesia, nerve pain and symptoms of heart failure like swelling of limbs and shortness of breath.

Rarity: Ultra rare

Top Symptoms: abdominal pain (stomach ache), shortness of breath, anxiety, chest pain, distal numbness

Urgency: Hospital emergency room

Moderate to severe hypothermia

With prolonged exposure to freezing cold, the body can lose the ability to maintain a safe core temperature. If this continues for long enough, you can become confused or even lose consciousness

Rarity: Ultra rare

Top Symptoms: coldness, alertness level change, pale skin, slow heartrate (under 60bpm)

Symptoms that never occur with moderate to severe hypothermia: shivering

Urgency: Emergency medical service

Slow heart rate treatments and relief

Preparing for your appointment

Your physician will want to know the type and frequency of any symptoms you are experiencing, so it's best to keep a diary. Notable symptoms include palpitations, dizziness, fainting, chest pain, shortness of breath, or reduced ability to exercise. Certain cardiac conditions run in families, so your physician will want to know about any relatives who passed away suddenly or have diagnosed cardiac problems.

Monitoring and testing

Your physician will likely start with a thorough evaluation that may include monitoring for hours to days. This will help determine if your heart rate is normal or if it will require treatment.

• EKG: This simple test measures the electric current as it runs through your heart and provides important information to your physician. It's painless, takes just seconds, and involves only a few pads that will be placed on your chest.
• Holter monitor: This is a portable EKG-like machine that you can wear for several days. This will enable your physician to monitor your heart rate and rhythm over a longer period and find any potential abnormalities. Loop recorders are also used for prolonged monitoring.
• Echocardiogram: In some cases, your physician will order an ultrasound to examine the structure of the heart, including the valves and strength of contraction.

Medical treatments

Your physician may prescribe the following, depending on the diagnosis.

• Medications: Some medications will raise the heart rate or treat any arrhythmias that may be contributing to your slow heart rate.
• Artificial or external pacemaker: In certain cases, a physician will decide to insert a pacemaker in the heart. A pacemaker provides a regular electrical current to the heart so that it contracts regularly and at a healthy rate and rhythm. Some pacemakers operate continuously while others only "kick in" when the heart rate falls below a set threshold rate.