Description, Causes and Risk Factors:
Slowness of the heartbeat, usually defined (by convention) as a rate under 50 beats/min.
Heart is made up of four chambers — two upper chambers (atria) and two lower chambers (ventricles). The rhythm of heart is normally controlled by a natural pacemaker — the sinus node — located in the right atrium. The sinus node produces electrical impulses that normally start each heartbeat.
From the sinus node, electrical impulses travel across the atria, causing the atria muscles to contract and pump blood into the ventricles. The electrical impulses then arrive at a cluster of cells called the atrioventricular node (AV node) — usually the only pathway for signals to travel from the atria to the ventricles.
The AV node slows down the electrical signal before sending it to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the muscles of the ventricles, they contract, causing them to pump blood either to the lungs or to the rest of the body.
Bradycardia is caused by something that disrupts the normal electrical impulses controlling the rate of your heart's pumping action. Many things can cause or contribute to problems with your heart's electrical system, including:
Diseases that damage the heart's electrical system. These include coronary artery disease, heart attack, and infections such as endocarditis and myocarditis.
Conditions that can slow electrical impulses through the heart. Examples include having a low thyroid level (hypothyroidism) or an electrolyte imbalance, such as too much potassium in the blood.
Infection of heart tissue (myocarditis).
A complication of heart surgery.
Underactive thyroid gland (hypothyroidism).
Imbalance of electrolytes, mineral-related substances necessary for conducting electrical impulses.
Obstructive sleep apnea, the repeated disruption of breathing during sleep.
Inflammatory disease, such as rheumatic fever or lupus.
Hemochromatosis, the buildup of iron in organs.
Some medicines for treating heart problems or high blood pressure, such as beta-blockers, antiarrhythmics, and digoxin.
Changes in the heart that are the result of aging.
Heavy alcohol use.
Use of illegal drugs.
Psychological stress or anxiety.
High blood pressure.
Symptoms may include:
Feel short of breath and find it harder to exercise.
Have chest pain or a feeling that your heart is pounding or fluttering (palpitations).
Feel confused or have trouble concentrating.
Faint, if a slow heart rate causes a drop in blood pressure.
Feel dizzy or lightheaded.
Your doctor may be able to diagnose bradycardia by doing a physical exam, asking questions about your past health, and doing an electrocardiogram (EKG or ECG). An EKG measures the electrical signals that control heart rhythm, so it is the best test for bradycardia.
But bradycardia often comes and goes, so a standard EKG done in the doctor's office may not find it. An EKG can identify bradycardia only if you are actually having it during the test.
You may need to use a portable (ambulatory) electrocardiogram. This lightweight device is also called a Holter monitor or a cardiac event monitor. You wear the monitor for a day or more, and it records your heart rhythm while you go about your daily routine.
Exercise test. Your doctor may monitor your heart rate while you walk on a treadmill or ride a stationary bike to see whether your heart rate increases appropriately in response to physical activity.
Electrophysiology (EP) study.
Tilt table test. This test helps your doctor better understand how your bradycardia contributes to fainting spells. You lie flat on a special table, and then the table is tilted as if you were standing up. Changes in the position may cause a fainting spell and help your doctor to establish a link between your heart rate and fainting episodes.
Your doctor may also use a monitoring device to better understand the cause of unexplained fainting episodes. These monitoring devices include:
Insertable loop recorder.
External loop recorder.
The goal of treatment is to raise your heart rate so your body gets the blood it needs. If severe bradycardia is not treated, it can lead to serious problems. These may include fainting and injuries from fainting, as well as seizures or even death. How bradycardia is treated depends on what is causing it.
If another medical problem, such as hypothyroidism or an electrolyte imbalance, is causing a slow heart rate, treating that problem may cure the bradycardia.
If a medicine is causing your heart to beat too slowly, your doctor may adjust the dose or prescribe a different medicine. If you cannot stop taking that medicine, you may need a pacemaker.
If damage to the heart's electrical system causes your heart to beat too slowly, you will probably need to have a pacemaker. A pacemaker is a device placed under your skin that helps correct the slow heart rate. People older than 65 are most likely to have a type of bradycardia that requires a pacemaker.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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