extrasystole

Generality

The extrasystole is an arrhythmia of the heart characterized by impulses of cardiac contraction (systoles) having a premature appearance and / or a place of origin other than the atrial sinus node

There has been much discussion on the correct definition of extrasystole, which literally means "added beat", but which actually represents a premature systole; for this reason, the extrasystole is sometimes referred to as premature beat or ectopic beat (to emphasize the origin of the pulse other than the sinoatrial node).

The extrasystoles can be isolated phenomena (which appear sporadically) or consecutive phenomena (which follow one after the other → extrasystoles in pairs, triplets or salve); moreover, they can alternate regularly with one or more normal beats, so that the heart rhythm is called bigemino, trigemino or quadrigemino, based on the normal extrasystole-systole cadence.

The extrasystole is by far the most common cardiac arrhythmia, both in healthy individuals and in individuals with heart (cardiopathic) disorders. The causes are different and depend on the state of health of the affected individual: in a cardiopathic individual, the extrasystole is linked to the diseased heart, while in a healthy subject it may depend on various factors, such as alcohol and smoking abuse, coffee, fatigue physical, or mental stress. The diagnosis is performed mainly by electrocardiogram and the therapy depends on the presence, or not, of a cardiopathy underlying the extrasystolic episode.

NB: to understand some concepts illustrated in the article, it is necessary to have the bases of anatomy and physiology of the heart illustrated in the general article on cardiac arrhythmias.

What is an extrasystole?

The extrasystole is an arrhythmia of the heart characterized by abnormal cardiac contraction impulses (systoles), having one or both of the following characteristics:

1. Premature appearance compared to the normal stimulus. It interferes with impulse conduction.
2. Ectopic origin, ie the site of origin of the impulse is different from the atrial sinus node.

These two characteristics interfere with the normal sinus rhythm, which originates from the dominant marker center, or even replace it.

The extrasystoles are, by far, the most frequent arrhythmias, so that some cardiologists affirm that every individual, at least once in their life, has presented an episode of premature / ectopic systole.

Extrasystoles appear in different ways. They can be:

1. Sporadic . Extrasystole is an isolated phenomenon .
2. In pairs . Two extrasystolic phenomena occur one after the other.
3. A hi . It is the term that indicates the succession of three or more extrasystolic phenomena.

Furthermore, it may happen that one or more extrasystoles are inserted into the normal sinus rhythm with a proper cadence. In other words, it is possible to create a regular alternation between extrasystoles and normal beat. In these cases, the rhythm is defined:

1. Bigemino, if there is an alternation between a normal beat and an extrasystole.
2. Trigeminal, if systolic terns consisting of a normal beat and two extrasystoles occur; or from two normal beats followed by an extrasystole.
3. Quadrigemino, if the succession of four systoles is composed of an extrasystole and three normal beats.

The extrasystoles, as we have said, can also be distinguished for the place of origin . Therefore, based on the marker (dominant or secondary) that generates the premature systole, the following classification can be drawn:

1. Sinus extrasystoles . These are very rare events. The origin of the premature beat lies in a part of the atrial sinus node which is slightly different from that which usually acts as the dominant marker.
2. Atrial extrasystoles . They rank second in an appearance frequency scale. The contraction impulse, premature with respect to the sinus one, can be generated in any point of the musculature of the atrium. The effects depend on how early the onset of extrasystoles is: the earlier it is, the greater the probability that the ventricles are still not excitable in the diastolic phase (ie relaxation). Therefore, the ventricular myocardium does not contract, although it receives the stimulus.
3. Atrioventricular junctional extrasystoles . They are infrequent and reside in third place due to their frequency of appearance. The precise area of ​​origin is near the atrioventricular node, or in the bundle of His, that is between atria and ventricles. The impulse, generated between the two cardiac cavities, can propagate towards both, stimulating the atria or the ventricles first. As a result, therefore, the conduction of the impulse is disordered and anomalous.
4. Ventricular extrasystoles . They are by far the most frequent premature systoles. Originate in any point of the ventricles and can propagate towards the atria. The extrasystole of the ventricles is followed by the sinus stimulus, which, however, runs into the non-excitability of the myocardium (as it has recently received a premature stimulus). Therefore there is no effective response to normal heartbeat. This lack of muscular receptivity results in a pause, called compensatory with a "loss of heart rate" sensation.

It should be noted that those listed above are just some of the characteristics of the various extrasystoles. In fact, each of them presents further details, useful for the cardiologist to define a complete diagnosis. However, we have mentioned the moment in which the extrasystole appears, and how it fits into the normal heartbeat, since this moment (early or late diastole) is important to understand the effects of an extrasystole on cardiac output . Diastole is the phase in which the heart is relaxing, after contracting to pump blood into the circulation: this is the time it takes for the myocardium to "recharge" and be receptive again to a new impulse. An extrasystole that arises in early diastole, will find the myocardium very little receptive to the stimulus; vice versa, an extrasystole that appears in late diastole will find a myocardium more susceptible to the passage of the impulse. This also affects the sinus beat following extrasystoles and cardiac output, which will therefore be compromised.

Causes

The causes that determine an extrasystole are different and depend on the state of health in which the individual affected by a premature systole finds himself.

Remembering that the extrasystoles are the most frequent arrhythmic episodes, if they arise in a healthy individual, as it is easy to happen, they are NOT to be considered cardiopathies, as they are not, for the cardiologist, of clinical importance. The determining factors of these non-pathological premature systoles are:

1. Tobacco.
2. Coffee and tea abuse.
3. Alcohol.
4. Reflexes vagal or sympathetic stimulations, coming from the abdominal organs.
5. States of fatigue, physical and mental.
6. Anxiety and anxiolytic drugs.
7. Pregnancy.

During pregnancy, extrasystoles are fairly frequent and persist until delivery; after that, they cease. Therefore, in the absence of other signs that may suggest heart disease, they must not arouse apprehension.

The picture regarding extrasystoles associated with heart disease is very different . In this case, the causes, that is heart diseases, are much more serious and require more attention. A simple extrasystole, in fact, can give rise to arrhythmias with more serious consequences. Self:

1. The extrasystole is supraventricular, it can turn into atrial flutter or atrial fibrillation.
2. The extrasystole is ventricular, it can turn into ventricular fibrillation. They are by far the most dangerous.

Heart diseases linked to extrasystolic episodes are:

1. Heart failure.
2. Valvular disease.
3. Ventricular hypertrophy.
4. Myocardial infarction.

Finally, there are other pathological situations, not concerning the heart, which can cause extrasystoles. They are:

1. Hyperthyroidism.
2. Gastrointestinal disorders (example: gastroesophageal reflux).
3. Hypertension.
4. Imbalances of electrolytes (hypokalemia; hypercalcemia; hypomagnesemia).

Symptoms

Most extrasystoles are not felt by the affected person. This is due to the fact that they are minor events. The feeling is of a missing beat or a more intense beat .

When the extrasystoles appear as blanks (that is, at least three successive premature systoles), heartbeat disturbances are more easily perceived.

The other typical symptoms are:

1. Troublesome sensation in the chest, similar to the whirring of wings.
2. Cardiopalmus (or palpitation).
3. Anxiety.
4. Dizziness.
5. Nausea.
6. Pallor.
7. Lipotimia (weakness).

Diagnosis

Accurate diagnosis requires a cardiological examination. The traditional tests, valid for the evaluation of any arrhythmic / extrasystolic episode, are:

1. Wrist measurement.
2. Stethoscopy.
3. Electrocardiogram (ECG).
4. Dynamic electrocardiogram according to Holter.

Wrist measurement . The cardiologist can draw fundamental information from the evaluation of:

1. Arterial pulse . The measurement is performed on the radial artery (at the level of the wrist). It informs about the frequency and regularity of the heart rhythm.
2. Jugular venous pulse . It is useful for understanding the type of extrasystole present.

Stetoscopy . Listening to noises and murmurs is very useful, for example, to distinguish an aortic or pulmonary valve stenosis from a stenosis of the atrioventricular valves.

Electrocardiogram (ECG) . It is the instrumental examination indicated to evaluate the progress of the electrical activity of the heart. Based on the traces that result, the doctor can estimate the severity and the causes of the extrasystoles.

Dynamic electrocardiogram according to Holter . This is a normal ECG, with the very advantageous difference that monitoring lasts for 24-48 hours, without preventing the patient from performing normal daily activities. It is useful when extrasystolic episodes are sporadic and unpredictable.

Anamnesis, that is, the collection of information by the physician of what the patient describes with regards to extrasystolic attacks also plays an important role in the diagnosis. The anamnesis is necessary because, as has been said, the extrasystoles arise, frequently and with episodes distant days / weeks from each other, even in those who do not have pathological disorders of other nature. These individuals, unless the extrasystolic attack is in progress, show a normal ECG trace, making a correct diagnosis impossible.

Therapy

The episodes of extrasystoles, in people without heart disorders, do not require specific therapeutic interventions. This applies even if the events are frequent. It is, however, recommended:

1. Moderate caffeine or alcohol consumption.
2. Not smoking.
3. Reduce stress and anxiety without using drugs.

In other words, by correcting certain behaviors and safeguarding one's health more, it is possible to stem the problem associated with premature systoles.

The behavior to adopt for extrasystoles of cardiac origin is different. In these cases, therapeutic treatment can be pharmacological, electrical or surgical .

The drugs used are:

1. Antiarrhythmics . They are used to normalize the heart rhythm. For example:
   1. quinidine
   2. Procainamide
2. Beta-blockers . They are used to slow down the heart rate. For example:
   1. Metoprolol
   2. Timolol
3. Calcium channel blockers . They are used to slow down the heart rate. For example:
   1. Diltiazem
   2. Verapamil

It should be pointed out that the extrasystole of pathological origin is a symptom. Therefore, the simple administration of antiarrhythmic drugs is not sufficient to solve the problem.

If at the origin of the problem there is a heart disease, the electrical treatment usually consists of the so-called transcatheter radiofrequency ablation .

This technique makes use of a catheter which, once carried to the heart, is able to infuse a radiofrequency discharge by affecting the area of ​​myocardium that generates the extrasystole (that is, the pedestal center that replaces the atrial sinus node). The affected area is destroyed and this should bring back control of the contraction impulses in the hands into the atrial sinus node.

Surgical treatment, on the other hand, is aimed at solving the basic heart problem and therefore depends on the diagnosed heart disease. If, for example, the patient suffers from an aortic stenosis, the surgical intervention aimed at repairing the heart valve function also restores the normal rhythm of the heart.

Finally, as we have seen, some extrasystoles are caused by non-cardiac pathological states. Even in these cases, the disappearance of premature systoles follows the treatment of the diagnosed underlying disease. This is the case, for example, of electrolyte imbalances, for which therapy consists in the administration of magnesium supplements (if the patient suffers from hypomagnesemia) or potassium (if the patient suffers from hypokalemia). One proceeds in the same way in the presence of hyperthyroidism, treating the latter first, as it causes extrasystoles.

Prevention

On the basis of what has been said, in order to prevent extrasystole episodes, it is necessary to eliminate those risk factors that can contribute to developing a heart disease. Avoiding smoking, for example, in addition to averting immediate extrasystolic phenomena, also removes the risk of developing heart disease in the future. Equally important is physical activity, the development of which (as long as it is seen as an entertainment and not as an obligation) has positive effects on the states of anxiety and stress that can affect an individual. It has been observed that physical exercise reduces extrasystoles in many subjects.