When your heart's rate is too rapid, it may not effectively pump blood to the rest of your body, depriving your organs and tissues of oxygen. This can cause these tachycardia-related signs and symptoms:
- Shortness of breath
- Rapid pulse rate
- Heart palpitations — a racing, uncomfortable or irregular heartbeat or a sensation of "flopping" in the chest
- Chest pain
- Fainting (syncope)
Some people with tachycardia have no symptoms, and the condition is only discovered during a physical examination or with a heart-monitoring test called an electrocardiogram.
When to see a doctor
A number of conditions can cause a rapid heart rate and tachycardia symptoms. It's important to get a prompt, accurate diagnosis and appropriate care. See your doctor if you or your child experiences any tachycardia symptoms.
If you faint, have difficulty breathing or have chest pain lasting more than a few minutes, get emergency care, or call emergency number. Seek emergency care for anyone experiencing these symptoms.
Tachycardia is caused by something that disrupts the normal electrical impulses that control the rate of your heart's pumping action. Many things can cause or contribute to problems with the heart's electrical system. These factors include:
- Damage to heart tissues from heart disease
- Abnormal electrical pathways in the heart present at birth (congenital)
- Disease or congenital abnormality of the heart
- Sudden stress, such as fright
- High blood pressure
- Drinking too much alcohol
- Drinking too many caffeinated beverages
- Medication side effects
- Abuse of recreational drugs, such as cocaine
- Imbalance of electrolytes, mineral-related substances necessary for conducting electrical impulses
- Overactive thyroid (hyperthyroidism)
In some cases, the exact cause of tachycardia can't be determined.
Electrical circuitry of the heart
Your heart is made up of four chambers — two upper chambers (atria) and two lower chambers (ventricles). The rhythm of your 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.
Types of tachycardia
Tachycardia occurs when a problem in electrical signals produces a heartbeat that is faster than normal. Common types of tachycardia include the following:
- Atrial fibrillation.Atrial fibrillation is a rapid heart rate caused by chaotic electrical impulses in the atria. These signals result in rapid, uncoordinated, weak contractions of the atria.
The chaotic electrical signals bombard the AV node, usually resulting in an irregular, rapid rhythm of the ventricles. Atrial fibrillation may be temporary, but some episodes won't end unless treated.
Most people with atrial fibrillation have some structural abnormalities of the heart related to such conditions as heart disease or high blood pressure. Other factors that may contribute to atrial fibrillation include a heart valve disorder, hyperthyroidism or heavy alcohol use.
- Atrial flutter.In atrial flutter, the heart's atria beat very fast but at a regular rate. Atrial flutter is caused by irregular circuitry within the atria.
The fast rate results in weak contractions of the atria. The rapid signals entering the AV node cause a rapid and sometimes irregular ventricular rate. Episodes of atrial flutter may get better on their own, or the condition may persist unless treated.
People who experience atrial flutter often experience atrial fibrillation at other times.
- Supraventricular tachycardia (SVT).Supraventricular tachycardia, which originates somewhere above the ventricles, is caused by abnormal circuitry in the heart, usually present at birth, that creates a loop of overlapping signals.
In one form of SVT, an abnormality in the AV node may "split" an electrical signal into two, sending one signal to the ventricles and another back to the atria.
Another common abnormality is the presence of an extra electrical pathway from the atria to the ventricles that bypasses the AV node. This may result in a signal going down one pathway and up the other. Wolff-Parkinson-White syndrome is one disorder featuring an extra pathway.
- Ventricular tachycardia. Ventricular tachycardia is a rapid heart rate that originates with abnormal electrical signals in the ventricles. The rapid heart rate doesn't allow the ventricles to fill and contract efficiently to pump enough blood to the body. Ventricular tachycardia is often a life-threatening medical emergency.
- Ventricular fibrillation.Ventricular fibrillation occurs when rapid, chaotic electrical impulses cause the ventricles to quiver ineffectively instead of pumping necessary blood to the body. This serious problem is fatal if the heart isn't restored to a normal rhythm within minutes.
Most people who experience ventricular fibrillation have an underlying heart disease or have experienced serious trauma, such as being struck by lightning.
Any condition that puts a strain on the heart or damages heart tissue can increase your risk of tachycardia. Lifestyle changes or medical treatment may decrease the risk associated with the following factors:
- Heart disease
- High blood pressure
- Heavy alcohol use
- Heavy caffeine use
- Use of recreational drugs
- Psychological stress or anxiety
Other risk factors
Other factors that may increase the risk of tachycardia include:
- Older age. Aging-related wear on the heart makes you more likely to develop tachycardia.
- Family. If you have a family history of tachycardia or other heart rhythm disorders, you may have an increased risk of tachycardia.
Complications of tachycardia vary in severity depending on such factors as the type of tachycardia, the rate and duration of a rapid heart rate, and the existence of other heart conditions. Possible complications include:
- Blood clots that can cause a stroke or heart attack
- Inability of the heart to pump enough blood (heart failure)
- Frequent fainting spells
- Sudden death, usually only associated with ventricular tachycardia or ventricular fibrillation
The most effective way to prevent tachycardia is to reduce your risk of developing heart disease. If you already have heart disease, monitor it and follow your treatment plan to lower your tachycardia risk.
Prevent heart disease
Treat or eliminate risk factors that may lead to heart disease. Take the following steps:
- Exercise and eat a healthy diet. Live a heart-healthy lifestyle by exercising regularly and eating a healthy, low-fat diet that's rich in fruits, vegetables and whole grains.
- Maintain a healthy weight. Being overweight increases your risk of developing heart disease.
- Keep blood pressure and cholesterol levels under control. Make lifestyle changes and take medications as prescribed to correct high blood pressure (hypertension) or high cholesterol.
- Stop smoking. If you smoke and can't quit on your own, talk to your doctor about strategies or programs to help you break a smoking habit.
- Drink in moderation. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women of all ages and men older than age 65, and up to two drinks a day for men age 65 and younger. For some conditions it's recommended that you completely avoid alcohol. Ask your doctor for advice specific to your condition. If you can't control your alcohol consumption, talk to your doctor about a program to quit drinking and manage other behaviors related to alcohol abuse.
- Don't use recreational drugs. Don't use stimulants, such as cocaine. Talk to your doctor about an appropriate program for you if you need help ending recreational drug use.
- Use over-the-counter medications with caution. Some cold and cough medications contain stimulants that may trigger a rapid heartbeat. Ask your doctor which medications you need to avoid.
- Limit caffeine. If you drink caffeinated beverages, do so in moderation.
- Control stress. Avoid unnecessary stress and learn coping techniques to handle normal stress in a healthy way.
- Go to scheduled checkups. Have regular physical exams and report any signs or symptoms to your doctor.
Monitor and treat existing heart disease
If you already have heart disease, you can take steps to lower your risk of developing tachycardia or another arrhythmia:
- Follow the plan. Be sure you understand your treatment plan, and take all medications as prescribed.
- Report changes immediately. If your symptoms change or get worse or you develop new symptoms, tell your doctor immediately.