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Why is it important to monitor heart function and how is electrocardiography (ECG) used for diagnosis?

What are arrhythmias

Heart rhythm disorders, or arrhythmias, are among the common diseases in the population. They arise from the different generation or conduction of electrical impulses in the heart.

From a prognostic point of view, these may be benign forms that may cause symptoms and reduce the quality of life, arrhythmias associated with a range of potential complications and health risks, up to malignant arrhythmias that directly threaten the life of the patient, often requiring immediate therapeutic intervention.

The normal heart rate is 60-90 per minute, the normal rhythm is called sinus rhythm. In the case of cardiac arrhythmias, the heart rhythm may be abnormally fast (tachycardia) or slow (bradycardia).

In tachycardia, an electrical excitation occurs at a different location than normally in the sinus node. It can arise at any point in the musculature of the atria and ventricles, and the electrical impulse may circulate in different parts of the heart, thus causing a very rapid heartbeat. Tachycardias originating in the atrial musculature are called supraventricular, while tachycardias originating in the ventricular region are called ventricular.

In bradycardia, the electrical impulse in the sinus node is formed more slowly than normal or the conduction of the impulse is interrupted somewhere on its way to the ventricular musculature. Any other area of the atrial or ventricular musculature can become an alternate site of excitation, and this alternate rhythm is usually slower and less stable than sinus rhythm.

How arrhythmias manifest themsleves and what types of arrhythmias we recognise

Typical symptoms of cardiac arrhythmias are palpitations, a skipping sensation in the heart region, but also shortness of breath, pressure in the chest, dizziness or fatigue. In some cases, the first manifestation is a syncope (short loss of consciousness), which can lead to an uncontrollable fall. The most severe arrhythmias can present themselves as sudden cardiac death.

The most common arrhythmia in the adult population is atrial fibrillation. Its frequency in the population increases significantly with age. It is characterised by chaotic atrial activity with irregular transmission of electrical impulses to the ventricles. People suffering from this arrhythmia usually complain of irregular heartbeats of varying intensity. However, a significant proportion of these people are completely asymptomatic, which poses a major problem in its early diagnosis and treatment. The absence of problems does not reduce the health risks of arrhythmias. Patients with atrial fibrillation are particularly at risk of stroke and heart failure. However, they are also significantly more likely to develop dementia and kidney failure earlier. Atrial fibrillation leads to more frequent hospital admissions and a generally reduced quality of life. The diagnosis of this disability consists of documenting the arrhythmia on an electrocardiographic recording (ECG).

Other arrhythmias that originate in the atria include premature contractions (atrial extrasystoles).  These are either completely asymptomatic or may manifest as skipping of the heart sensation. In some cases, they can also trigger atrial fibrillation. Atrial extrasystoles can be clustered as runs of atrial tachycardia, which can manifest themselves as rapid palpitations. However, patients often report only reduced performance, fatigue or other non-specific complaints.

Rapid and regular arrhythmias referred to as supraventricular tachycardia can be found in many patients. Their common denominator is an unpleasantly perceived fast run of the heart, often accompanied by vegetative accompaniment (heat, feeling like vomiting or fainting). The onset and end of an arrhythmia is usually sudden, usually lasting only tens of seconds or minutes. Therefore, it happens that the physician is forced to repeatedly perform ambulatory monitoring of the heart rhythm (ECG Holter monitor), which, however, is completely unprofitable when performed outside of difficulties. Patients often fail to receive a correct diagnosis for a long time.

If the rhythm disturbance originates in the heart ventricle, we speak of ventricular arrhythmias. Most often, these are premature contractions from the ventricles (ventricular extrasystoles). Ventricular extrasystoles are often benign but may indicate incipient significant heart disease. In the case of numerous extrasystoles, a decrease in left ventricular function and heart failure may occur. Sometimes ventricular extrasystoles build up to forms of non-sustained ventricular tachycardia.

The most dangerous form of ventricular arrhythmias are the so-called sustained ventricular tachycardias. These can directly threaten the patient's life. There is an increased risk of these arrhythmias in people with structural heart disease, especially in the presence of coronary artery disease (e.g. after myocardial infarction) or with a congenital genetic predisposition and often a familial history. If the above heart rhythm disturbances are detected, it is important to consult a specialist who will appropriately indicate the investigation of the cause of the heart rhythm disturbance.  In individual cases, a cardioverter-defibrillator implantation may be indicated as a prevention of sudden cardiac death.

In general, the diagnosis of a specific rhythm disorder is quite crucial. Because only when the specific type of arrhythmia is known, it is possible to optimally target treatment, which may consist of properly adjusted drug therapy. Treatment can also be causal, using electrophysiological testing followed by catheter ablation in specialised cardiovascular centres.

The opposite of fast arrhythmias are slow arrhythmias (called bradycardia). Collectively, these are various forms of slow heart rate, which manifests itself in reduced performance, shortness of breath, fatigue, but often also collapse. The cause is a disturbance in the generation or conduction of the heart impulse. If a prognostically significant pause or slow heart rate is detected, often correlating with the reported symptoms, a pacemaker is implanted.

example - SR (healthy ECG)
Healthy EKG scan
example - AF (ECG fibrilace síní)
unhealthy EKG scan

Monitoring of Arrhythmias

Arrhythmias can occur at any time of the day.  This fact makes it significantly more difficult to detect in the physician's office, even with random outpatient ECG monitoring (ECG Holter monitor). It is clearly demonstrated that the length of the ECG recording correlates with the chance of detecting a heart rhythm disturbance. The longer and more frequent the ECG monitoring, the higher the probability of arrhythmia detection. However, even after the diagnosis is made, regular ECG monitoring is important to confirm the effect of treatment, detect any recurrences and determine the heart rate in arrhythmia. This monitoring has a great influence on further treatment and reduction of arrhythmia-related risks.

Despite all the possibilities of modern medicine and the golden standard of ECG evaluation on a 12-lead recording in a physician's office, the most important thing is repeated and prolonged ECG monitoring with high-quality equipment with the possibility of accurate interpretation of ECG findings. Only a sufficient duration of monitoring, a good quality recording and its correct evaluation can lead to a correct assessment of the patient's heart rhythm. In addition, it can help the physician with an optimal, and above all individual, approach, which reduces the complications of arrhythmias and improves the quality of life.