Any disorder that causes the heart rhythm abnormal is known as cardiac arrhythmia. The beats are produced as a result of electrical impulses that allow the chambers of the heart – the atria and ventricles – to contract properly, synchronously and rhythmically. An average heart rate is between 60 and 100 beats per minute.
However, the heart rate alone is not enough to diagnose an arrhythmia. In fact, for example, 50 beats per minute can be considered normal for a trained athlete. “Apart from the heart rate, there has to be a clinical context that is not normal,” says the expert.
Cardiac arrhythmias can appear for the following reasons, the electrical impulse is not appropriately generated, originates in the wrong place, or the paths for electrical conduction are altered.
Arrhythmias are a widespread heart problem. It is estimated that only the most frequent type, atrial fibrillation, affects more than 4% of people over 40 years of age.
The causes of arrhythmias are very diverse. These are some of the factors that explain its appearance:
Many arrhythmias are linked to ageing. “With ageing, the system that creates the heart’s impulses also ages and disorders occur that make it beat more slowly,” explains Jiménez Candil. With age, the frequency of rapid arrhythmias also increases, in which the heart beats faster than normal.
Cardiovascular risk factors
Classic cardiovascular risk factors influence the appearance of arrhythmias. For example, hypertension, sleep apnea, obesity and diabetes are some of the diseases most closely linked to heart rhythm disturbances.
Structural diseases of the heart
Certain diseases that affect the heart’s structure, such as myocardial infarction or valvular heart disease, can lead to a heart malfunction since arrhythmias are generated in certain cases.
Some are born with a genetic predisposition to have arrhythmias and are people with familial heart disease.
no known cause
When the cause cannot be identified, they are idiopathic arrhythmias.
The clinical manifestations depend on the type of arrhythmia. They can vary, ranging from arrhythmias without symptoms to others that cause important repercussions. The main symptoms are:
Under normal conditions, the heartbeat is not perceived. The perception that the heart beats is known as palpitations; palpitations do not always indicate a pathological situation or mean that there is tachycardia.
Some affected people may experience dizziness and even syncope. The relatively sudden loss of consciousness is known as syncope and is characterised by a spontaneous recovery in a short period. Some syncopes may be due to slow arrhythmias ( bradycardias ) and others to fast arrhythmias or tachycardias.
- Fatigue or tiredness
Intolerance to exertion, tiredness, fatigue, choking sensation when walking, and chest pain are other possible manifestations of some arrhythmias.
- Sudden death
Sudden death is a cardiac arrest that occurs unexpectedly and suddenly. It is primarily triggered by cardiac arrhythmia, mainly ventricular fibrillation, but also ventricular tachycardia and, less commonly, bradycardia.
Among the measures that can be adopted to prevent the formation of arrhythmias, the following stand out:
- Reduce the consumption of sugars and fats to reduce hypercholesterolemia and diabetes.
- Play sports regularly.
- No smoking.
- Avoid alcohol.
- Control and reduce stress levels.
We can find the following types of arrhythmias:
- sinus bradycardia
This is a situation where the heartbeat originates and transmits normally, but the heart rate is slower than normal.
Sinus bradycardia can occur in different situations: it can be completely normal and physiological, as is the case with athletes; it may be due to certain medications; to the involvement of the sinus node itself and can be found in the context of an involvement known as bradycardia/tachycardia syndrome in which patients alternate episodes of significant bradycardia with gusts of tachycardia episodes (usually atrial fibrillation).
Isolated sinus bradycardia is usually a physiologic condition and does not require treatment. , Drugs can also cause it, and the possibility of withdrawing them must be assessed. If it is severe and symptomatic, the treatment is the implantation of a pacemaker.
- Ventricular fibrillation
In this arrhythmia, the heart’s electrical activity is totally disorganized, so there is no effective beat. This situation systematically leads to severe cardiac arrest, which, if cardiac resuscitation cannot be stopped, is irreversible and causes death.
People who suffer from it
This type of arrhythmia occurs mostly in patients with heart disease and, especially, has involvement in the coronary arteries, and the arrhythmia may be its first manifestation. Exceptionally, ventricular fibrillation can also occur in patients who only have a disorder of the electrical properties of the heart. They are usually young patients, and, in most cases, a genetic component has been found, so it is not uncommon for these patients to have a family history of sudden unexplained death.
Among the most well-known electrical abnormalities that can cause sudden death due to ventricular fibrillation, it is worth highlighting:
- Congenital long QT syndrome is a hereditary disease in which episodes of ventricular tachycardia occur, generally short and self-limited, which can degenerate into ventricular fibrillation. It can manifest itself from childhood and is characterized by episodes of loss of consciousness that are usually triggered by emotional situations or effort. The diagnosis is usually made from the baseline electrocardiogram (ECG), although this may be practically normal in some cases. Family history can help make the diagnosis. Some forms of this syndrome can be accompanied by congenital deafness.
- Brugada syndrome. It is a hereditary familial disease in which affected patients may present repeated syncope and sudden death. The definitive diagnosis is given by the ECG, which presents some characteristic alterations. In patients with this syndrome, the ECG may be transiently normal. In these cases, if there is clinical suspicion, the diagnosis can be made by performing a drug test that can reveal the ECG alteration.
Acute episodes of ventricular fibrillation (VF): This is a vital emergency in which cardiopulmonary resuscitation manoeuvres must be started immediately, including cardiac massage, ventilation and urgent cardiac defibrillation.
- Chronic VF treatment: In the VF treatment approach, whether the VF is due to a specific cause must be established. Thus, for example, in some patients, the VF episode occurs during the myocardial infarction. In these cases, only myocardial infarction should be treated. In all other situations, since the possibility of recurrence and therefore of sudden death is very high, an implantable cardioverter-defibrillator should be indicated, which, although it will not prevent new VF crises from occurring, will allow them to be treated promptly. Immediate and automatic, preventing the patient from dying.
- atrial fibrillation
It is the most common cardiac arrhythmia. It is generated because the atria are activated and contract in a disorganized, irregular and inefficient way, which causes the ventricle to beat irregularly.
It can be paroxysmal (occurs in short episodes lasting less than a week and usually comes and goes on its own), persistent (when episodes last more than a week and often do not go away without treatment), or permanent (occurs constantly).
There are several therapeutic options for patients who present repeated AF crises.
- Drugs: Various antiarrhythmic drugs may be helpful. It should be noted, however, that no drug is effective in all patients and that they may have serious side effects or contraindications that limit their use.
- Radiofrequency ablation of the AV node and implantation of a pacemaker: This alternative consists of causing a heart block with radiofrequency and subsequently implanting a pacemaker. With this technique, the AF is not eliminated, but the patient stops noticing the vibrations, and their symptoms improve.
- Direct radiofrequency ablation of AF: In some highly selected patients with specific types of AF, it may be considered to perform an ablation directed at the points where the AF begins, which could be curative.
Paroxysmal supraventricular tachycardia (PSVT)
These are episodes of tachycardia that usually start suddenly without any specific trigger, although it can sometimes start with exercise or bending over. The episodes can vary, ranging from minutes to several hours. They usually stop spontaneously and abruptly, although sometimes medical assistance is required to stop the tachycardia, either through some type of manoeuvre or drugs.
The symptoms are rapid and regular palpitations, although syncope, chest pain or other discomforts may occasionally occur. In addition, there is a specific type of PSVT in which patients report a localized throbbing sensation in the neck.
People who suffer from it
It is not uncommon for the patient to have been diagnosed with a nervous breakdown. These tachycardias can occur at any age and can be found in newborns to the elderly. It is not usually associated with any other cardiac disorder or abnormality.
The ECG outside the seizures is normal, except for an anomaly that is the Wolff-Parkinson-White syndrome, in which an abnormality is detected in the ECG even without tachycardia. In other cases, an electrophysiological study should be performed if an ECG is not recorded during the crisis.
Most acute PSVT crises resolve spontaneously after several minutes. If they persist, some type of treatment should be considered. The first measure that must be tried to stop a problem is the so-called vagal manoeuvres. If the tachycardia does not subside despite this, intravenous antiarrhythmic treatment should be administered.
Patients who have presented a PSVT crisis usually present recurrences. To avoid recurrences, there are two therapeutic alternatives:
- Antiarrhythmic drugs must be administered continuously; they are only effective 50 per cent of the time and can have side effects.
- Radiofrequency ablation: in this type of tachycardia, given its high effectiveness (90 per cent) and low frequency of complications.
Ventricular Tachycardia (VT)
People who suffer from it
They originate in the ventricle and often occur in patients with heart disease but can occasionally occur in healthy people.
The symptoms that can cause VT can be highly variable. Thus, they can be completely asymptomatic, manifest only with palpitations; or give more severe symptoms such as dizziness, sweating, syncope, or sudden death.