This alteration in the frequency of the heartbeat can be fatal in some cases.
We have all felt our hearts race at some point. We see someone who attracts us, we are nervous or stressed, we have an anxiety crisis, we exercise … our heart races to a greater or lesser extent in all these cases.
However, sometimes this acceleration is excessive and even dangerous, exceeding normal values and may require medical intervention. We are talking about tachycardias. In this article we will see the main types of tachycardias, their symptoms and possible causes.
Tachycardia: concept and symptoms
We understand by tachycardia 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 who had a heart rate greater than one hundred beats per minute would suffer tachycardia, which could reach up to around four hundred. It is an arrhythmia or alteration of the heart rate, like bradycardia (although the latter would be the opposite of tachycardia, that is, 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, not being able to carry enough oxygen to the rest of the body. Although most of those that happen to us do not involve serious damage, they can reduce the life expectancy of the heart muscle and can predict and even cause myocardial infarctions.
Some of the typical symptoms of tachycardia are the presence of dizziness, a feeling of suffocation and weakness (due to a lack of enough oxygen), as well as breathing difficulties. The presence of palpitations, tremors in the chest and pain in this one is frequent.
Tachycardia can also cause alterations in the level of consciousness, including syncope or fainting. However, in some cases tachycardias are asymptomatic, which carries 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 elements, both physical and psychic. Thus, the presence of some type of arrhythmia or heart rate alteration such as tachycardia can have very different origins. These are the most frequent causes.
- Coronary diseases
- Lung diseases
- Substance abuse
- Electrolyte imbalance
- Excessive physical effort
- Anxiety crisis or excessive stress
- Administration of antiarrhythmic medications
- Lack of oxygen
- Scars on the heart muscle
- Thyroid problems
- High cholesterol
- Diabetes (in some cases of hypoglycemia)
Different types of tachycardias
There is a wide variety of elements that can cause tachycardia. These elements cause some type of morphological or functional alteration of any part of the heart. Thus, we can find the following types of tachycardia.
1. Sinus tachycardia
This type of tachycardia is what usually occurs during episodes of anxiety, during states of anemia, in people with heart failure, after exercising or after consuming substances such as alcohol. It does not require treatment by itself, although it is necessary to influence the element that caused it.
2. Supraventricular tachycardias
It is an acceleration in the heart rate whose origin can be found in alterations in the functioning of the atria, the upper chambers of the heart. They can also occur due to problems in the atrioventricular node, the node that joins the atria and ventricles. There are different types of supraventricular tachycardias, such as the following.
These types of tachycardia occur in a specific area of the atria. They last a long time and are often difficult to remove. They tend to stem from chronic conditions such as bronchitis, and need to be treated medically or even surgery may be required to restore normal function.
During an episode of atrial fibrillation, the heart rate begins to accelerate, with irregular changes in the beat pattern. It is common in the elderly.
It 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 attacks. It should be treated pharmacologically both to stop the arrhythmia and to reduce the possibility of new episodes and possible thrombi.
It is a type of tachycardia in which there is an increase in heart rate, reaching around 150 beats per minute on a regular basis. It is caused during the atrial reentry process, a phenomenon in which part of the heart has not been activated in time together with the rest of the organ and acts by causing a greater number of beats by causing new ones.
Paroxysmal supraventricular tachycardias
This type of tachycardia is also due to alterations in the atria, but in the case of paroxysmal ones, the acceleration of the heart rate begins and ends in a searching way.
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 reentry phenomenon described above. The presence of arrhythmia is treated from vagal stimulation or pharmacologically, in addition to requiring preventive measures to avoid future cases.
Within this group we can also find nodal reentrant tachycardia and tachycardia involving the accessory pathway, these two cases being due to alterations in the atrioventricular node.
3. Ventricular tachycardias
They are due to problems originating in the ventricles. This type of tachycardia is considered malignant, since they present a certain danger to life. They are more common than supraventricular tachycardias in people with heart disease.
Within this group we can find several types of tachycardia, including the following.
There is a problem or alteration in a specific point of the ventricle. This alteration causes the heartbeat to go ahead compared to usual, with a small pause until the arrival of the next normal beat. They may not give symptoms, and if they do not occur in subjects with heart disease, they usually do not have a bad prognosis, although in cases where they cause discomfort, they can be treated medically.
Sustained ventricular tachycardia
Due to problems or an alteration in the functioning of the ventricles, the heart rate continually rises to abnormal levels. It is one of those with the greatest danger of death. They usually cause loss of consciousness and obvious symptoms such as dizziness, pain, and palpitation.
This type of tachycardia usually indicates the presence of heart disease, which should be investigated to avoid future outbreaks. This type of tachycardia can be treated with a defibrillator to regain normal rhythm or with drugs. It may require surgery to install internal defibrillators to avoid possibly fatal arrhythmias.
Nonsustained ventricular tachycardia
Brief episodes of tachycardia occasionally occur that end spontaneously. In nonsustained ventricular tachycardia, a set of consecutive pulses occur that subside in less than thirty seconds. If there is heart disease, it is usually associated with a poor prognosis and should be monitored and preventive treatment. There is a possibility of sudden death.
It is a potentially fatal type of tachycardia, and consciousness is frequently lost during it. The heartbeat ceases to present a fixed pattern, not having an effective frequency but rather the organ beats in a disorganized way, with different intensity and with a variable temporal separation between beats.
- Goldberger, A .; Goldberger, Z. & Schvilkin, A. (2006) Clinical Electrocardiography: A Simplified Approach, 7th ed. Philadelphia: Mosby Elservier.
- Uribe, W., Duque, M. & Medina, E. (2005). Electrocardiography and Arrhythmias. Bogotá: PLA Export Editores Ltda.