We’ve all felt our hearts race at one time or another. We see someone we are attracted to, we are nervous or stressed, we have an anxiety attack, we exercise… our heart speeds up to a greater or lesser extent in all these cases.

However, sometimes such acceleration is excessive and even dangerous, exceeding normal values and may require medical intervention. We are talking about tachycardia. In this article we will see the main types of tachycardias , their symptoms and possible causes.

Tachycardia: concept and symptoms

We understand tachycardia as any acceleration or increase in the heart rate that exceeds the values considered normal . This value is usually around one hundred beats per minute in adult subjects. Thus, those people with a heart rate higher than one hundred beats per minute would suffer from tachycardia, which can reach around four hundred. This is an arrhythmia or alteration of the heart rate, just like bradycardia (although the latter would be the opposite of tachycardia, i.e., in bradycardia the heart rate slows down while in tachycardia it accelerates).

The exaggerated increase in heart rate causes the heart to pump blood too quickly , and it cannot carry enough oxygen to the rest of the body. While most of these do not involve serious damage, they can reduce the life expectancy of the heart muscle and may predict and even cause heart attacks.

Some of the typical symptoms of tachycardia are the presence of dizziness, choking sensation and weakness (due to lack of sufficient oxygen), as well as breathing difficulties. The presence of palpitations, chest tremors, and chest pain is common.

Tachycardia also can cause alterations in the level of consciousness , including syncope or fainting. However, in some cases, tachycardias are asymptomatic, which entails the risk of detecting them too late.

Risk factors and possible causes

The human heart is an organ that can be affected by a large number of both physical and psychic elements. Thus, the presence of some kind of arrhythmia or alteration of the heart rate such as tachycardia can have very different origins . These are the most frequent causes.

  • Hypertension
  • Arteriosclerosis
  • Coronary heart disease
  • Lung diseases
  • Substance abuse
  • Electrolyte imbalance
  • Tumors
  • Infections
  • Excessive physical effort
  • Anxiety or excessive stress crises
  • Administration of antiarrhythmic drugs
  • Lack of oxygen
  • Scars in the heart muscle
  • Thyroid problems
  • High cholesterol
  • Diabetes (in some cases of hypoglycemia)

Different types of tachycardia

There are a wide variety of elements that can cause a tachycardia. These elements cause some kind of morphological or functional alteration of some part of the heart . Thus, we can find the following types of tachycardia.

1. Sinus tachycardia

This type of tachycardia is usually produced during episodes of anxiety, during states of anaemia, in people with heart failure, after exercise or after consuming substances such as alcohol. It does not require treatment per se, although it is necessary to address the element that has caused it.

2. Supraventricular tachycardias

This is an acceleration in the heart rate that can be traced to alterations in the functioning of the atria, the upper chambers of the heart. They may also occur due to problems in the atrioventricular node, the node that links the atria and ventricles. There are different types of supraventricular tachycardias , such as the following.

Atrial tachycardia

These types of tachycardia occur in a specific area of the atria. They have a long duration and are often complicated to eliminate . They usually result from chronic disorders such as bronchitis, and need to be treated medically or surgery may even be required to restore normal functioning.

Atrial fibrillation

During an episode of atrial fibrillation, the heart rate begins to accelerate, with irregular changes in the heartbeat pattern . This is common in the elderly.

This is the most common type of arrhythmia and may or may not cause symptoms. However, it is linked to the appearance of thrombi and ischemic accidents. It must be treated pharmacologically both to stop the arrhythmia and to reduce the possibility of new episodes and possible thrombi.

Atrial Flutter

This is a type of tachycardia in which the heart rate increases, reaching around 150 beats per minute on a regular basis. It is caused during the process of atrial re-entry , a phenomenon in which part of the heart has not been activated in time with the rest of the organ and acts by provoking a greater number of beats by provoking new ones.

Paroxysmal supraventricular tachycardia

This type of tachycardia is also due to alterations in the atria, but in the case of paroxysmal tachycardia the acceleration of the heart rate begins and ends in a searching manner.

In this case they usually cause symptoms and do not go unnoticed, causing shortness of breath, chest pain, discomfort and palpitations . They usually occur due to the re-entry phenomenon described above. The presence of the arrhythmia is treated by vagal or pharmacological stimulation, in addition to requiring preventive measures to avoid future cases.

Within this group we can also find reentrant nodal tachycardia and tachycardia involving the accessory pathway, these two cases being due to alterations in the atrioventricular node.

3. Ventricular tachycardia

They are due to problems originating in the ventricles. This type of tachycardia is considered malignant, as it presents a certain danger to life . They are more frequent than supraventricular tachycardias in people with heart disease.

Within this group we can find several types of tachycardia, including the following.

Ventricular Extras

There is a problem or disturbance at a particular point in the ventricle. This alteration causes the heartbeat to be earlier than usual , with a small pause until the arrival of the next normal heartbeat. They may not give symptoms, and if they do not occur in subjects with heart disease they do not usually have a bad prognosis, although in cases where they cause discomfort they can be treated medically.

Sustained ventricular tachycardia

Due to problems or a disturbance in the functioning of the ventricles, the heart rate rises to out-of-normal levels continuously. This is one of the most life-threatening . They often cause loss of consciousness and obvious symptoms such as dizziness, pain and palpitation.

This type of tachycardia usually indicates the presence of a heart disease, which should be investigated to avoid future outbreaks. This type of tachycardia can be treated with a defibrillator to restore a normal rhythm or with drugs. It may require surgery to install internal defibrillators to prevent possibly fatal arrhythmias.

Non-sustained ventricular tachycardia

Sometimes brief episodes of tachycardia occur that end spontaneously . In the case of non-sustained ventricular tachycardia, a set of consecutive impulses are given that cease in less than thirty seconds. If heart disease is present, it is usually associated with a poor prognosis and should be followed up and treated preventively. There is a possibility of sudden death.

Ventricular fibrillation

This is a potentially fatal type of tachycardia, and it is common to lose consciousness during it . The heartbeat no longer has a fixed pattern, not having an effective frequency but rather the organ beats in a disorganized manner, with different intensity and with a variable temporal separation between beats.

Bibliographic references:

  • Goldberger, A.; Goldberger, Z. & Schvilkin, A. (2006) Clinical Electrocardiography: A Simplified Approach, 7th ed.
  • Uribe, W., Duque, M. & Medina, E. (2005). Electrocardiography and arrhythmias. Bogotá: P.L.A. Export Editores Ltda.