Definition and Overview
Tachycardia refers to an abnormally high resting heart rate (more than 100 beats per minute). It occurs due to problems with the heart’s electrical system. When the heart beats too fast, it becomes less efficient in pumping blood to the rest of the body. This can put a strain on the heart muscle and may lead to a heart attack.
The disorder can be mild, moderate, or severe. Most people with a mild form of the disorder do not have symptoms. In fact, many are able to live normal and even active lives. In more severe cases, on the other hand, patients require treatment. This may involve the use of drugs or surgery.
There are five types of the disorder, namely:
Atrial fibrillation (AF) - This causes fast and irregular heartbeat. It occurs when the heart’s atria do not beat the way they should. Their beat is not in synch with the way the ventricles move. This makes the heart quiver. AF increases the risk of heart failure and stroke.
Ventricular fibrillation - This is the most serious type. It occurs when the lower chambers of the heart quiver. It can cause the heart to lose its ability to pump blood. This can lead to a heart attack.
Supraventricular tachycardia (SVT) - Most SVT episodes are caused by problems with electrical connections in the heart. Some cases, on the other hand, occur due to surgery or certain diseases.
Atrial flutter - This causes fast but regular heartbeats. This means that the heart beats the way it should but only faster. It occurs when an abnormal conduction circuit forms inside the right atrium.
Ventricular tachycardia - This causes fast heart rhythm that starts in the lower part of the heart. Just like atrial flutter, it causes rapid but regular heartbeat.
Causes of Condition
The heart’s main function is to pump blood to the rest of the body. It ensures that other vital organs, such as the kidneys and the brain, receive the nutrients and oxygen they need to function properly. The heart needs electrical impulses in order to beat. These impulses are produced by the sinus node, which is also known as the heart’s natural pacemaker. The electrical impulses from the sinus node travel to the atria to make the atrial muscles contract. They then move to the atrioventricular (AV) node. Here, they slow down to allow ventricles to fill with blood. They then travel to the ventricles so the blood can flow out of the heart. Anything that disrupts this system can cause heart rhythm problems. Common causes are:
Congenital abnormalities that damage the heart and its electrical system.
Lifestyle factors, such as drug and alcohol abuse as well as smoking.
Adverse reaction to certain drugs.
Certain illnesses that cause damage to the heart tissue and valves.
Certain diseases, such as anaemia and high blood pressure.
The disorder affects millions of people from around the world. However, not all have symptoms. Aside from having a fast heart rate from time to time, many do not have any other signs. The disorder also does not prevent them from living an active life. However, in some cases, the condition can result in shortness of breath, fast pulse, and heart palpitations. In severe cases, fainting, sudden weakness, and low blood pressure are very common. Other symptoms include chest pain, confusion, and dizziness.
Who to See and Types of Treatments Available
People with the disorder are treated by heart specialists. A number of tests are used to make a diagnosis and identify the source of the problem.
For the first part of the consultation, the doctor will conduct a physical exam and review the patient’s medical history. One of the things that doctors would want to know is if the patient has a family history of heart disease.
The doctor will then assess the heart’s electrical activity with an electrocardiogram (ECG). This is a simple, painless test that can be done in the hospital or at a doctor’s office. In addition to this test, patients may also need to wear portable monitors. These record the heart’s electrical activity for a longer period (at least 24 hours).
More tests are done if the monitors detect an abnormal heart rhythm. One of which is the electrophysiological test (EPS). This helps doctors understand where the abnormal heartbeat is coming from. During an EPS, a thin tube is inserted into a blood vessel that leads to the heart. Electrical signals are then sent to the heart, and the electrical activity is recorded.
Imaging tests are also used. These provide still and moving pictures of the heart. These can be used to confirm if the heart is enlarged or if blood vessels in the area are blocked.
Mild cases may not require the use of drugs or surgery. In some people, the heart rate can be slowed down with vagal maneuvers. These include holding the breath and bearing down, gagging or coughing, or immersing the face in cold water. For more severe cases, an artificial pacemaker or ICD device may be used. These devices are implanted under the skin. If they detect any abnormality in the heart rhythm, they fire electrical shocks to restore normal heartbeat.
Doctors reserve open-heart surgery as the last option because of its many risks and possible complications. It is only used if structural abnormalities or an extra electrical pathway causes the disorder. It is also useful if the patient has another heart problem that can only be treated with surgery.
Neumar RW, Otto CW, Link MS, et al. (November 2010). “Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care”. Circulation. 122 (18 Suppl 3): S729–67.
Custer JW, Rau RE, eds. Johns Hopkins: The Harriet Lane Handbook. 18th ed. Philadelphia, PA: Mosby Elsevier Inc; 2008. Data also available through eMedicine: Pediatrics, Tachycardia.