Atrial fibrillation: definition, causes, symptoms, diagnosis and treatment
Atrial fibrillation consists of an alteration in heart rhythm. The pathology does not allow effective contraction of the atrial cavities and, as a result, this affects the proper functioning of the ventricles and, therefore, the progression of blood flow
This type of arrhythmia reduces the efficiency of the heart pump, which, in order to ensure adequate perfusion, responds with an increase in speed and force of contraction, which is why it is a potentially dangerous disease.
It is important to recognise it as soon as it occurs and treat it appropriately.
According to statistics, the percentage of the world population that suffers from atrial fibrillation is around 0.5-1%, in fact, in Italy there are more than 600,000 people affected by this pathology.
Atrial fibrillation: what is it?
Atrial fibrillation originates in the upper cavities of the heart, called atria, and consists of an alteration in heart rhythm.
In a patient suffering from atrial fibrillation, the atria fail to contract synchronously but do so very rapidly and irregularly.
To better understand what atrial fibrillation consists of, one must first understand how the heart’s electrical activity works
With each heartbeat, an electrical impulse propagates first to the right atrium and then to the left atrium.
This ‘shock’ allows the atria to contract and the heart to pump blood into the ventricles.
This type of electrical impulse originates from a group of myocardial cells, contained within the sinoatrial node, present in the right atrium.
In a person suffering from atrial fibrillation, the electrical activation is rapid and apparently chaotic and thus leads the atria to fibrillate; the high frequency of atrial contraction can affect the ventricles, causing an accelerated heartbeat (tachycardia).
The pathology leads to an impairment of the cardiac muscle’s ability to contract (contractility).
As a consequence, the cardiac output also becomes irregular as the myocardium is unable to pump blood properly to make it flow to the various parts of the body and meet the body’s needs.
This, in addition to the unpleasant cardiac sensations, leads to fatigue and exhaustion as well as posing a health hazard.
As mentioned above, atrial fibrillation is a cardiac arrhythmia, i.e. an alteration of the heart rate.
Under normal conditions, the heart rhythm, also called ‘sinus’ rhythm, varies between 60 and 100 beats per minute.
During an atrial fibrillation, on the other hand, the frequency can vary between 100 and 175 beats per minute.
The incidence of this type of cardiac abnormality increases with age and is, therefore, more common among the elderly.
As far as gender is concerned, it seems that atrial fibrillation affects both men and women, although, especially in European countries, it is the former who suffer the most.
As we will see more clearly later, the disorder can develop either due to certain heart diseases or due to factors that do not necessarily depend on the heart muscle.
Different types of atrial fibrillation
Clinically, one can distinguish 3 types of atrial fibrillation, which can be classified according to their severity, duration and mode of manifestation.
- Paroxysmal atrial fibrillation: lasting less than 7 days;
- Persistent atrial fibrillation: lasting more than 7 days;
- Permanent atrial fibrillation: lasting more than 1 year.
From a clinical point of view, the last two forms of fibrillation are more severe than paroxysmal fibrillation.
Let us look specifically at the differences between these three types of arrhythmia.
Paroxysmal atrial fibrillation
Paroxysmal atrial fibrillation is characterised by a sudden onset.
Unlike the other two types, which we will see later, it is transient in nature and has a short duration ranging from a few minutes to a couple of days (it generally does not exceed 48 hours); in the most severe cases, it can resolve within a week.
Paroxysmal atrial fibrillation is characterised by a very high heart rate.
In fact, the pulse can reach a value of more than 140 beats per minute.
Being transient in nature, paroxysmal fibrillation has no specific therapy although, in some cases, specific drugs may be prescribed to help restore the heartbeat to a normal rhythm.
Although it tends to resolve on its own, it is still a good idea to consult an arrhythmologist in order to receive the appropriate treatment and, if necessary, carry out further diagnostic investigations.
Persistent atrial fibrillation
As its name suggests, persistent atrial fibrillation is a form of atrial fibrillation that does not resolve spontaneously and lasts much longer than paroxysmal atrial fibrillation.
For these reasons, it requires specific treatment prescribed by a doctor.
A further difference between persistent and paroxysmal atrial fibrillation is a slightly lower heart rate of 100 to 140 beats per minute.
Permanent atrial fibrillation
This type of atrial fibrillation takes even longer than the first two forms and must be treated promptly and appropriately.
It is possible to suffer from permanent atrial fibrillation due to certain particular pathologies, most often cardiac, that lead this arrhythmia to become a stable condition.
For this reason, therapy must be aimed at counteracting the underlying pathology that induces the arrhythmia, otherwise it will remain a constant presence.
This type of atrial fibrillation also has a much lower frequency than paroxysmal atrial fibrillation and is, like persistent atrial fibrillation, around 100-140 beats per minute.
Patients suffering from fibrillation may experience, among the main symptoms
- Sense of dizziness;
- Palpitations or heart palpitations;
- Feelings of anxiety;
- Chest pain;
- Sense of weakness and lack of energy (asthenia);
- Poor capacity to withstand physical exertion.
The symptoms of fibrillation depend strictly on the degree of the pathology
For example, the symptoms of a paroxysmal type of atrial fibrillation are much more pronounced, as this form of arrhythmia causes the heart to beat at a very high frequency.
In many cases, however, atrial fibrillation gives no obvious symptoms for a long period of time.
This happens especially among young people, who may not notice their condition for a long time unless the condition is noticed by a doctor during a test or cardiological examination.
Not not noticing the problem in time can reduce the chance of restoring normal heart rhythm and lead to serious consequences.
This is why it is important and advisable to seek medical attention as soon as signs or symptoms of an arrhythmia occur and to perform regular electrocardiographic checks.
The causes that lead to this type of arrhythmia can be of a different nature.
Commonly, the onset of arrhythmia can be traced back to the ageing of the heart and the progressive dilatation of the atrium that generates the cardiac impulse, but it is also common among people who have thyroid problems, diabetics and in those suffering from high blood pressure.
But the causes do not end there; in summary, arrhythmia can be caused by:
- Pulmonary embolism;
- Acute and chronic ischaemic heart disease;
- Hypertensive heart disease;
- Restrictive heart disease;
- Inflammatory cardiopathies;
- Hypertrophic and dilated cardiomyopathies;
- Congenital heart diseases;
- Acute and chronic pneumopathies;
- Electrolyte disorders;
- Sleep apnoea;
There are also a number of bad habits and risk factors that can favour the onset of atrial fibrillation, among them:
- Alcohol, smoking and drug abuse;
- Drug abuse;
- Previous stroke;
- Heart failure;
- Diabetes mellitus;
- High blood pressure;
- Previous vascular disease;
Although not a condition that poses an immediate risk to the patient’s life, atrial fibrillation, if not treated in time, can lead to very serious health consequences.
These could include complications such as:
- Heart failure;
- Renal failure;
- Premature death.
Diagnosis and Treatment
To check whether a patient is suffering from atrial fibrillation, the following investigations may be prescribed:
- Resting heart rate measurement;
- Blood analysis;
- Electrocardiogram (ECG);
- Dynamic Holter electrocardiogram;
- Exercise testing;
- Chest X-ray.
Treatments, on the other hand, vary depending on various factors such as the type, cause, extent of symptoms, the patient’s health and previous medical history.
The aims of therapy are to restore, maintain and control the normal rhythm of the heartbeat and prevent the formation of thrombi that can cause strokes.
To treat the arrhythmia, anti-arrhythmic drugs and special medicines can be used to prevent thrombus formation.
Atrial fibrillation can also be treated with a medical procedure called electrical cardioversion, carried out with a defibrillator, which resets the heartbeat and returns it to normal.
Transcatheter ablation, a surgical procedure that allows the removal of the area of cardiac tissue that triggers the cardiac arrhythmia, can also be used.
This type of intervention is only used if the treatment of the condition with the above-mentioned treatments is ineffective.