When the heart loses its rhythm

Risposta: The heart carries out continuous and extraordinarily intense work, which accompanies every moment of our lives. It has an electrical function, which generates and coordinates the rhythm of the heartbeats, and a mechanical function, that of a pump which propels blood throughout the body. Under normal conditions, the heart beats around 100,000 times a day, over 36 million times a year: figures that give an idea of the work it carries out over the course of a lifetime.

At the heart of every heartbeat is an electrical impulse that originates in the heart and spreads in an orderly manner, causing the atria to contract first, followed by the ventricles. This system works a bit like an internal clock, but it does not always maintain the same rhythm: the heart beats faster during physical exertion or when we experience strong emotions, and slower during rest and sleep. However, when the formation or propagation of these impulses is disrupted, the heart may beat too fast, too slowly or irregularly. This is what we call cardiac arrhythmia.

The most common example is premature beats, which occur earlier than expected and may be felt as a ‘flutter’, a stronger thud in the chest or the sensation that the heart is skipping a beat. They can occur even in the absence of heart disease and may be triggered by stress, tiredness, lack of sleep or excessive caffeine and alcohol intake. When they occur in isolation and the heart is structurally healthy, they are usually harmless, although in some cases further investigation may be advisable.

The situation is different for arrhythmias that are more prolonged and complex. Atrial fibrillation, caused by irregular electrical activity in the atria, results in an irregular and often rapid heartbeat. It is one of the most common arrhythmias, particularly with advancing age, and requires specific assessment as it can promote the formation of blood clots in the heart and increase the risk of stroke. It is therefore important to recognise it even when it causes few symptoms, in order to identify those individuals for whom anticoagulant therapy is indicated. Arrhythmias do not always present in the same way. Palpitations – that is, the unusual sensation of one’s own heartbeat – are the best-known symptom, but they do not necessarily indicate a dangerous arrhythmia. Conversely, even significant changes in heart rhythm may go largely unnoticed. If palpitations are new, frequent, prolonged or associated with shortness of breath, weakness, dizziness, reduced exercise tolerance, chest pain or loss of consciousness, further investigation is required. Particular attention should be paid to fainting or transient loss of consciousness, known as syncope. These can have a wide variety of causes, not necessarily cardiac in nature, but they must be assessed because they are sometimes caused by an excessively slow heart rate (bradycardia) or by a sudden and significant increase in heart rate (atrial or ventricular tachycardia). The severity depends on the cause, the condition of the heart and the risk of recurrence. Key factors in the assessment include whether the episode occurs during exertion, without any warning signs, in people with known heart disease or with a family history of serious arrhythmias or sudden cardiac death. The first test is usually an electrocardiogram (ECG), which records the heart’s electrical activity. However, it only captures a few seconds at a time: if the arrhythmia is intermittent, it may not be present at that moment. A Holter monitor, which records the heart rhythm over several days, or longer-term monitoring systems may therefore be used. Smartwatches and wearable devices can also be useful in selected cases, on medical advice. Echocardiograms, blood tests or other investigations are decided upon based on the clinical picture.

The key is to avoid the two extremes: do not panic straight away at the first sign of an irregular heartbeat, but do not ignore persistent signs or those associated with significant symptoms either. Understanding which type of arrhythmia is present and in what kind of heart it occurs allows us to distinguish between what is not a cause for concern and what requires monitoring and treatment. When the heart loses its rhythm, it is not just a question of how fast or irregularly it beats, but above all why it is doing so and whether it is occurring in a healthy heart or in the presence of heart disease.