An arrhythmia describes an irregular heartbeat - the heart may beat too fast (tachycardia), too slowly (bradycardia), too early (premature contraction), or irregularly (fibrillation).
Arrhythmias occur when the electrical signals to the heart that coordinate heartbeats are not working properly. Many heart arrhythmias are harmless.
Some people experience irregular heartbeats, which may feel like a racing heart or fluttering. However, if they are particularly abnormal, or result from a weak or damaged heart, arrhythmias can cause serious and even potentially fatal symptoms.
Contents of this article:
Fast facts on arrhythmias
Here are some key points about arrhythmias. More detail and supporting information is in the main article.
Symptoms of arrhythmia
An arrhythmia is an irregular heart rhythm.
Some patients may have no symptoms at all, but a doctor might detect an arrhythmia during a routine examination.
Even if a patient notices symptoms, it does not necessarily mean there is a serious problem. Ironically, some patients with life-threatening arrhythmias may have no symptoms while others with symptoms may not have a serious problem.
Symptoms of tachycardia
(Sometimes there are no symptoms)
- Syncope (fainting, or nearly fainting)
- Fluttering in the chest
- Sudden weakness
Symptoms of bradycardia
(Sometimes there are no symptoms)
- Angina (chest pain)
- Trouble concentrating
- Difficulties when exercising
- Fatigue (tiredness)
- Shortness of breath
- Syncope (fainting or nearly fainting)
Symptoms of atrial fibrillation
(These often develop rapidly although, sometimes, there are no symptoms)
- Angina (chest pain)
- Syncope (fainting, or nearly fainting)
Causes of arrhythmia
A number of factors can induce arrhythmias, including some recreational drugs.
Any interruption to the electrical impulses that cause the heart to contract can result in arrhythmia. The human heart consists of four chambers, all of which must contract in the right way at the right time to produce a natural heart rhythm.
For a person with a healthy heart, they should have a heart rate of between 60 and 100 beats per minute when resting.
The more fit a person is, the lower their resting heart rate. Olympic athletes, for example, will usually have a resting heart rate of under 60 beats per minute because their hearts are very efficient.
A number of factors can cause the heart to work incorrectly, they include:
- Alcohol abuse
- Drug abuse
- Excessive coffee consumption
- Heart disease
- Hypertension (high blood pressure)
- Hyperthyroidism (an overactive thyroid gland)
- Mental stress
- Scarring of the heart, often the result of a heart attack
- Some dietary supplements
- Some herbal treatments
- Some medications
A healthy person will hardly ever suffer from long-term arrhythmia unless they have an external trigger, such as drug abuse or an electric shock. If there is an underlying problem, however, the electrical impulses may not be able to travel through the heart correctly, increasing the likelihood of arrhythmia.
Arrhythmia can develop if a condition has changed the structure of the heart, for instance:
- Coronary artery disease - arteries in the heart narrow, often resulting in a heart attack
- Cardiomyopathy - disease of the myocardium (heart muscle)
- Valvular heart diseases - if the heart valves narrow or leak, the heart muscle can stretch and thicken
Types of arrhythmia
Atrial fibrillation - irregular beating of the atrial chambers - usually fast. Atrial fibrillation is common and mainly affects older patients.
Instead of producing a single, strong contraction, the chamber fibrillates (quivers). In some cases, the heartbeat of a person with atrial fibrillation can reach 350 beats per minute and, in extreme cases, up to 600.
Atrial flutter - the difference between flutter and fibrillation is that flutter is coordinated while fibrillation is not. In other words, during a flutter, the heart contracts properly, but in fibrillation, the contractions are more random, and the heart beat does not push the blood through the heart successfully. Some patients may experience both flutter and fibrillation.
Atrial flutter can be a serious condition. A patient with atrial flutter will typically experience 250 to 350 beats per minute.
Supraventricular tachycardia (SVT) - a regular, abnormally rapid heartbeat. The patient experiences a burst of accelerated heartbeats that can last from a few seconds to a few hours. Typically, a patient with SVT will have a heart rate of between 160 and 200 beats per minute.
Ventricular tachycardia - abnormal electrical impulses that start in the ventricles and cause an abnormally fast heartbeat. This often happens if the heart has a scar from a previous heart attack. Usually, the ventricle will contract more than 200 times a minute.
Ventricular fibrillation - an irregular heart rhythm consisting of very rapid, uncoordinated fluttering contractions of the ventricles. The ventricles do not pump blood properly, they simply quiver. Ventricular fibrillation is life-threatening and usually associated with heart disease. It is often triggered by a heart attack.
Long QT syndrome - a heart rhythm disorder that sometimes causes rapid, uncoordinated heartbeats. This can result in fainting, which may be life-threatening. It is sometimes caused by a genetic susceptibility or certain medications.
A slow heartbeat (under 60 beats per minute) does not necessarily mean there is a problem. Physically fit people with a healthy, strong heart often have a low resting heart rate.
Bradycardia is only an issue if the heart is faulty and does not pump enough blood; examples include:
- Sick sinus - the sinus node is the heart's natural pacemaker. If it does not function properly, the resting heart rate may be abnormally low.
- Conduction block - a block of the electrical pathways of the heart. This can occur in or close to the atrioventricular node, located on the pathway between the chambers of the heart. The electrical impulses between the upper and lower halves of the heart may be slowed or blocked. If the signal is totally blocked, some cells can make a steady but slower heartbeat. The patient may experience skipped heartbeats or bradycardia but sometimes there are no symptoms.
Risk factors for arrhythmia
The following are possible risk factors for arrhythmia:
- Old age - the heart weakens with age.
- Inherited gene defects - people who are born with a heart abnormality.
- Heart problems - people with narrowed arteries, those who have had a heart attack, heart valves that do not function properly, previous heart surgery, and cardiomyopathy.
- Hypothyroidism or hyperthyroidism - problems with the thyroid gland.
- Medications - some prescription medications, and OTC drugs, such as cough and cold drugs containing pseudoephedrine.
- Hypertension - people with high blood pressure are much more likely to develop coronary artery disease and other heart problems.
- Obesity - obesity increases the risk of arrhythmia.
- Uncontrolled diabetes - patients with uncontrolled diabetes are more likely to develop arrhythmia compared to someone with diabetes who is receiving proper treatment.
- Obstructive sleep apnea - patients whose breathing stops briefly during the night.
- Electrolyte imbalances - electrolytes, such as calcium and potassium, are essential for the proper conduction of electricity between cells and through cells. If electrolyte levels are out of balance, it can result in arrhythmia.
- Heavy and regular alcohol consumption - people who regularly consume large quantities of alcohol.
- Too much caffeine - caffeine may accelerate the heart rate and eventually cause arrhythmias.
- Illegal drugs - amphetamines and cocaine can cause arrhythmias, especially ventricular fibrillation.
Diagnosis of arrhythmia
There are a number of ways to diagnose an arrhythmia. Often, multiple methods will be used.
The doctor will try to find out what triggers the patient's arrhythmia. This will involve a detailed interview which may include the patient's medical history, family history, diet, and lifestyle.
The following tests may be ordered:
Blood and urine tests - these will check the patient's blood count and liver, thyroid, and kidney function. They may also check for electrolytes and other chemicals.
ECG (electrocardiogram) - this device records the electrical activity and rhythm of the patient's heart.
Holter monitor - a wearable device that records the heart for one or two days. A button can be pressed when symptoms arrive - this allows the doctor to see what heart rhythms were present at that moment.
Echocardiogram - an ultrasound scan that checks the pumping action of the patient's heart.
Chest X-ray - the images help the doctor check the state of the patient's heart and lungs.
Tilt-table test - if the patient experiences fainting spells, dizziness, or lightheadedness, and neither the ECG nor the Holter revealed any arrhythmias, a tilt-table test may be performed.
Electrophysiologic testing (or EP studies) - an invasive, relatively painless, non-surgical test that can help determine the type of arrhythmia, why it is happening, and how it might respond to treatment.
Heart Catheterization - this procedure provides information on how well the heart is working. A thin, hollow tube called a catheter is inserted into a large blood vessel, usually in the groin. It is a relatively safe procedure.
Treatments for arrhythmia
Treatment for arrhythmia is only required if the condition is putting the patient at risk of a more serious arrhythmia or a complication.
Treatments for bradycardia
If the bradycardia is caused by an underlying condition, that condition needs to be treated first. If no underlying problem is found, the doctor may advise implanting a pacemaker.
A pacemaker is a small device that is placed under the skin of the chest or abdomen to help control abnormal heart rhythms. Pacemakers use electrical pulses to prompt the heart to beat at a normal rate.
Treatments for tachycardia
Vagal maneuvers - certain movements that the patient can do themselves might stop an arrhythmia that starts above the lower half of the heart. These movements may involve the patient holding their breath and straining, coughing, or submerging their face in ice-cold water.
Medications - these will not cure the patient, but are usually effective in reducing episodes of tachycardia.
Cardioversion - the doctor may use an electric shock or medication to reset the heart to its regular rhythm.
Ablation therapy - one or more catheters go through blood vessels into the inner heart. They are placed in areas of the heart that are thought to be the source of the arrhythmia and destroy small sections of the tissue.
ICD (implantable cardioverter-defibrillator) - the device is implanted near the left collarbone and has electrode-tipped wires that go from the ICD, through veins, to the heart. The ICD monitors the heart rhythm and if it detects an abnormally slow rhythm, it stimulates the heart to return to a normal rhythm.
Maze procedure - a series of surgical incisions are made in the heart. They then heal into scars and form blocks. These blocks guide the electrical impulses helping the heart to beat efficiently.
Ventricular aneurysm surgery - sometimes, an aneurysm (bulge) in a blood vessel that leads to the heart causes an arrhythmia. If other treatments do not work, a surgeon may remove the aneurysm.
Coronary bypass surgery - arteries or veins from elsewhere in the patient's body are grafted to the coronary arteries to bypass any regions that have become narrow, and improve the blood supply to the heart muscle (myocardium).
Complications of arrhythmia
Stroke - fibrillation (quivering) means that the heart is not pumping properly. This can cause blood to collect in pools and clots can form. If one of the clots dislodges it can travel to a brain artery, blocking it, and causing a stroke. Stroke can cause brain damage and can sometimes be fatal.
Heart failure - prolonged tachycardia or bradycardia can result in the heart not pumping enough blood to the body and its organs - this is heart failure. Treatment can usually help improve this.
Alzheimer's disease - There is a link between atrial fibrillation and the development of Alzheimer's disease, according to some research.