Comparative analysis of syncope (Atena Editora)

Abstract

Syncopes are common medical conditions characterized by sudden and transient loss of consciousness, together with diffuse cerebral hypoperfusion, associated with reduced blood flow to the brain and loss of postural tone with spontaneous recovery. There is a wide variety of studies that seek to understand and classify syncope, due to the wide scope of its origins, consequences and manifestations. However, the best-known classification divides them into three main types: Cardiogenic, Orthostatic and Reflex. Each of them contains subtypes, which can differ by etiology, most affected population, symptoms and treatment. Examples of these are Hypotensive, Neurogenic and Vasovagal syncope. These classifications help in the diagnosis and development of appropriate therapeutic approaches for each patient. Studies indicate that syncope, especially Vasovagal, has a correlation with family history, and may be hereditary and possibly explained by some yet unknown genetic component. Cardiogenic syncope is fainting caused by problems in the cardiovascular system. Elderly people, people with chronic illnesses, people taking medications that affect blood pressure or heart rate, and patients with heart disease are most affected by this type. Its main subdivision concerns arrhythmogenic syncope, which can affect people of any age group. This is caused by a cardiac arrhythmia, that is, a change in the heart's rhythm and depends on the type of arrhythmia present in the patient - bradycardia (slow or absent beat), tachycardia (fast and irregular beat) or heart block (interruption in electrical conduction). from heart). Bradycardia arrhythmia can cause an episode of syncope due to a reduction in heart rate (< 30 or 35 bpm) and, consequently, a reduction in cardiac output.

Although opposite, tachycardia (> 150 or 180 bpm) also results in a reduction in cardiac output, since there is a decrease in ventricular filling time and consequently a smaller volume of blood being pumped around the body. Finally, heart block, which involves high-grade atrioventricular blocks or structural blockages caused by cardiovascular diseases. In this group we have valve diseases, hypertrophic cardiomyopathy, atrial myxoma, pulmonary embolism and pulmonary hypertension, cardiac tamponade, coronary syndrome and finally acute aortic dissection. Among these causes, the two with the greatest population reach are aortic stenosis and hypertrophic cardiomyopathy (HCM). The first often leads to compensatory peripheral vasodilation induced by physical exercise, since the obstruction prevents the increase in cardiac output, and thus results in a drop in systemic blood pressure and cerebral hypoperfusion. HCM causes syncopal episodes in approximately 25% of patients with this disease, due to abnormality and atrioventricular conduction blocks, myocardial ischemia during exertion and subaortic obstruction.