Tachycardia – Supraventricular, Ventricular, Symptoms, Causes, Diagnosis, Treatment

By | May 5, 2015

Beating up of heart at faster rate is known as tachycardia. A healthy person will have 60-100 beats in a minute when he is at rest. A person having tachycardia will have increased heartbeat in his chambers. Actually the heart beats fast when the person receives increased electrical signals. Tachycardia may or may not cause any complications. In severe cases it can cause heart attack, stroke or even death. Treatments are available in the form of medications, fixing pacemaker and in treating the root cause of the problem.

Symptoms :

At normal rate the heart will be able to pump blood efficiently, but when the heart beats fast it may not pump enough blood to the body. This could cause deprivation of oxygenated blood to various organs. Some of the symptoms of tachycardia are shortness of breath, palpitation, rapid pulse rate, dizziness, chest pain and lightheadedness.

Some people may faint and fall down due to rapid heartbeat. Interestingly some people may not have any symptoms and tachycardia is diagnosed when the doctor examines the person for some other problem. If you have difficulty in breathing and chest pain with rapid heartbeat you need to seek emergency treatment.

Causes :

Tachycardia or rapid heartbeat occurs when there is disruption in the electrical impulses received by the heart. This can be caused due to several factors. Any damage to the tissues of the heart, heart infection or heart disease can alter the electrical signals. The problem can be congenital (inherited by birth). For some people it can develop due to congenital heart disease or abnormality in the heart.

Too much of exercises, sudden stress, sudden increase in blood pressure, anemia, smoking, alcoholism, substance abuse, high fever, and side effects of certain medications can cause tachycardia. It can develop when there is imbalance in the level of electrolytes which control the electrical impulses. In rare cases excess secretion of thyroid can cause tachycardia.

How electrical impulses control the heartbeat?

There are 4 chambers in the heart namely right auricle, right ventricle, left auricle and left ventricle. Auricles are located on the upper chambers and ventricles on the lower ones. There is a pacemaker (in-built) or the sinus node in the right atrium that controls the heartbeat. Electrical signals are generated from the sinus node that triggers the heart rhythm.

This signal travels through the atria making the inner muscles of the atrium to contract and expand thus pumping blood into the ventricles. There is an AV node present inside that monitors the electrical impulses before sending it to the lower chambers (ventricles). This delay will let the ventricles to fill up with blood. Once the electrical impulses reach the ventricles they would make them to contract thus pumping the blood to other organs of the body.

Types :

Some of the common types of tachycardia are given below:-

  • Atrial fibrillation :

This occurs when there is an irregular electrical signal in the atria generated in rapid rate. It would produce uncoordinated contractions in rapid rates releasing chaotic electrical impulses. This can be either temporary in many cases but in few people it has to be given treatment. This process can occur due to abnormal heart problems or due to sudden rise of blood pressure.

  • Atrial flutter :

The heartbeat is rapid in this type of flutter but the electrical signals are not chaotic. It can develop due to irregular circuit of impulses inside the atria.

  • Supraventricular Tachycardia :

This type of tachycardia occurs on the ventricles and is caused by overlapping of electrical signals in the heart. Very often this type is inherited by birth. Any abnormality in the ventricles will generate electrical signals rapidly which may then divide into two signals, one of which would go to the atria and the other to the ventricles.

  • Ventricular Tachycardia :

In this type abnormal signals are produced in the ventricles not allowing the rhythmic contraction of the ventricles. This would make them unable to produce sufficient volumes of blood that is required by the body. This type requires immediate treatment and hospitalization.

Who are at risk?

Any person having previous heart problem or hypertension is prone to develop tachycardia. But certain factors like smoking, drinking, increased consumption of substance, caffeine and heightened stress/anxiety can cause tachycardia. A person is likely to develop tachycardia if he/she has family history of this problem. Sudden trauma or injury to the heart and old age can also cause tachycardia.

Complications :

Serious life threatening situations can develop due to severe forms of tachycardia. The rate of damage would vary depending on the duration and rate of tachycardia. It can cause blood clots, heart failure, cardiac arrest and in extreme cases sudden death due to ventricular fibrillation.

Diagnosis :

Many procedures are available to determine the heartbeat and functions of heart. Electrocardiogram is the major test for detecting tachycardia. In this method electrodes are connected to the arms and chest which would record the electrical impulses generated in the heart. This would give a clear idea about the type of tachycardia and the type of abnormal problems in the heart.

Nowadays portable machines like holter monitor and event recorder are available for reading the heartbeat at home. Heart rhythms can be examined using holter monitor tool wherein the patient’s heartbeat is measured for 24 hours or even more. Any abnormality in the heart rhythm can be easily detected. In addition, electrophysiological test is also used for detecting problems in heart rhythm. Thin tubes are inserted into the groin or arms through which it is connected to the blood vessels that supplies blood to the heart. It would record the electrical signals produced in every beat detecting tachycardia.

Treatment :

Treatment method varies according to the health condition of the patient and the intensity of the episode of tachycardia. The ultimate goal would be to regularize the heartbeat. Your doctor would use vagal maneuvers to slow down the heartbeat. Simple physical movements can be used to reduce the rapid heart rhythm. Vagus nerve is the one that controls the heartbeat which gets automatically reduced when a person coughs or makes a bowel movement.

In severe cases your doctor would inject medications like flecainide or rythmol intravenously. These drugs are anti-arrhythmic thus regulating the heartbeat efficiently. The medications are also available in the form of pills. For some people, electric shock is sent into the heart through patches kept on the chest. This would control the electrical impulses generated inside and regulate the heartbeat into normalcy.

Prevention :

For patients who have history of tachycardia and those who are prone to develop this problem doctors would use preventive measures for slowing down the heartbeat. Catheter ablation process is administered if tachycardia occurs due to abnormal electrical impulses. A catheter is kept permanently inside the heart and the electrodes present in them would automatically generate high frequency energy to put off the extra electrical impulses generated due to tachycardia. This process is beneficial in preventing tachycardia arising due to atrial flutter or fibrillation.

Calcium channel blockers like calan, cardizem and beta blockers like esmolol or metoprolol is prescribed for preventing fast heart rate. Blood thinning drugs like warfarin or dabigatran are given to prevent future blood clots due to stroke. For some people pacemaker is kept inside the skin which would control the abnormal electrical impulses whenever they are generated. In some cases cardioverter defibrillator is implanted to prevent serious complications due to tachycardia. This device would send small shocks if it senses high electrical impulses which would regulate the heartbeat.

Surgery is done if the patient is not responding to any of the above methods. The surgeon would mess up the heart tissue so that it would not conduct electrical impulses at abnormal rate/speed. Blood thinning drugs like warfarin or dabigatran are given to prevent future blood clots due to stroke.

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