Your heart is a muscle that pumps blood through your body. Your heart rate is how fast your heart beats. Your heart should always have a regular, rhythmic beat, like the ticking of a clock.
What is an abnormal heart rhythm?
Abnormal heart rhythms are heartbeats that are:
Too fast (tachycardia—"tachy" means rapid)
Too slow (bradycardia—"brady" means slow)
Abnormal heart rhythms are also called arrhythmias.
Heart disorders are the most common cause of an abnormal heart rhythm
You may feel fine, but sometimes you can feel your abnormal heart rhythm (what you feel is called palpitations Palpitations Palpitations are the awareness of heartbeats. The sensation may feel like pounding, fluttering, racing, or skipping beats. Other symptoms—for example, chest discomfort or shortness of breath—may... read more )
Some abnormal heart rhythms make you feel weak or dizzy
Doctors do an electrocardiogram (ECG/EKG) Electrocardiography Electrocardiography is a test that measures your heart’s electrical activity. It's quick, painless, and harmless. The results of that test are shown in an electrocardiogram. It looks like a... read more to diagnose an abnormal heart rhythm
Many abnormal heart rhythms aren't serious and most can be treated
Some abnormal heart rhythms are dangerous and can be fatal
What controls my heart rhythm?
Your heart rhythm is controlled by:
Pacemaker cells in your heart
Hormones, minerals, and other substances in your blood
There are special pacemaker cells in a part of your heart called the SA node (sinoatrial node).
Pacemaker cells send out regular electrical signals to your heart muscle to make it contract
The pacemaker cells have their own natural rhythm of 60 to 100 signals per minute. However, nerves from your brain can send messages to the cells telling them to speed up or slow down.
The conduction system carries the pacemaker signals to the rest of your heart
The conduction system includes a gateway called the AV node (atrioventricular node). The AV node controls how signals pass from the upper chambers of your heart (atria) to the lower chambers (ventricles). When the conduction system is working properly, the signals get to each of your heart muscle cells at just the right time so your heart gives a good, strong beat that pumps blood properly.
Hormones, such as thyroid hormone What are thyroid hormones? Your thyroid is a gland below the Adam’s apple in the front of your neck. Glands make and release hormones. Hormones stimulate other cells or tissues into action. The thyroid makes thyroid hormones... read more made by your thyroid gland, affect your heart rhythm. Many drugs, medicines, and chemicals also affect your heart rhythm.
You also need the right balance of minerals (electrolytes Overview of Electrolytes Electrolytes are minerals that circulate in your blood. These minerals are also in your stomach juices, in your stool (poop), in your urine, and inside your body's tissues. Salt (sodium) is... read more , such as sodium and potassium) in your blood for your heart to beat properly.
What causes abnormal heart rhythms?
Your heart rhythm can become abnormal if there's a problem with:
Your pacemaker cells
Your heart's conducting system
Chemicals and drugs in your blood
The most common cause of a heart rhythm problem is a heart disorder, such as:
Heart valve disorders Overview of Heart Valve Disorders Your heart is a muscle that pumps blood through your body. Your heart has four chambers. The atria are the two upper chambers in your heart—the right atrium and the left atrium. The ventricles... read more such as aortic stenosis Aortic Stenosis The aorta is the main artery that carries blood away from your heart to the rest of your body. Four heart valves control how blood flows in and out of your heart. The valves are like one-way... read more
Coronary artery disease blocks blood flow to parts of your heart. This can damage the pacemaker cells or the conducting system.
Other causes of abnormal heart rhythms include:
Heart abnormalities you were born with
Sometimes doctors can't tell what's causing your abnormal heart rhythm.
What are the symptoms of an abnormal heart rhythm?
Your symptoms depend mainly on whether your heart is:
Pumping enough blood
Not pumping enough blood
If your heart is pumping enough blood, you may feel normal. Or you may feel like your heart is skipping beats (called palpitations). Some people say strong palpitations may feel like a fish flopping around in their chest.
If your heart is not pumping enough blood, you also may have:
Shortness of breath
Feeling light-headed or dizzy
Go to the doctor if you have any of these symptoms.
How can doctors tell if I have an abnormal heart rhythm?
Doctors feel your pulse and do:
An ECG is a quick, painless test that measures your heart’s electrical activity using stickers and cables on your chest, arms, and legs.
If the ECG shows an abnormal rhythm, doctors usually do other tests depending on your symptoms, including:
Blood tests to check hormone and electrolyte levels
Echocardiography Echocardiography and Other Ultrasound Procedures Echocardiography can be used to detect abnormalities in heart wall motion and to measure the volume of blood being pumped from the heart with each beat. This procedure can also detect abnormalities... read more (ultrasound of your heart)
If the ECG does not show an abnormality, it could be because your heart rhythm was not abnormal while you were having the test. Doctors then may have you:
Wear a small device under your clothes that records your heart's electrical activity for a day or more (event monitor Continuous Ambulatory Electrocardiography A standard electrocardiograph (ECG) records the heart's electrical activity for only a few seconds. This can detect abnormalities that are constant; however, sometimes abnormal heart rhythms... read more or Holter monitor Continuous Ambulatory Electrocardiography A standard electrocardiograph (ECG) records the heart's electrical activity for only a few seconds. This can detect abnormalities that are constant; however, sometimes abnormal heart rhythms... read more )
If doctors think you have a dangerous heart problem, they'll admit you to the hospital. You'll be in a unit where your heart rate and rhythm can be recorded and seen by the nurses and doctors.
If doctors need more information about your abnormal heart rhythm, they may do:
Electrophysiologic testing is like cardiac catheterization Cardiac Catheterization Cardiac is a medical term for the heart. Catheterization means to put a thin, hollow tube (catheter) into some part of your body. So in cardiac catheterization (cardiac cath): Your doctor puts... read more . Doctors insert a thin flexible tube (catheter) into a large blood vessel (for example, one in your leg) and thread it up into your heart. The catheter has electrodes on its tip that record your heart's electrical activity from the inside. The catheter can also stimulate your heart electrically to see how it responds.
How do doctors treat abnormal heart rhythms?
Some abnormal heart rhythms are harmless and don’t need treatment.
Sometimes, lifestyle changes help, such as:
Changing or stopping one of your medicines
Not drinking alcohol or caffeine
Not doing heavy exercise (if an abnormal heart rhythm happens during exercise)
Different abnormal rhythms require different treatment. Doctors may use:
An artificial pacemaker (a small electrical device that doctors put in your chest or belly to signal your heart when to beat)
An electrical shock to restore normal heart rhythm (called cardioversion, defibrillation, or electroversion)
A treatment called ablation to destroy the abnormal heart tissue
Artificial pacemakers sometimes include a defibrillator so the same device can trigger a normal heart beat or stop an abnormal rhythm with a shock. This combination device is called an ICD.
Doctors do ablation if they find that one small bit of heart tissue is causing the abnormal rhythm. Getting rid of the tissue often gets rid of the rhythm problem. Often they do ablation during electrophysiologic testing. They use a catheter to deliver a high-frequency electrical current that destroys a small area of the heart.
You may need to stop driving for a while until doctors know whether the treatment is working.