In patients who for any reason cannot undergo physical exercise, fatigue is achieved with pharmacological agents such as dipyridamole, adenosine and dobutamine…. Ischemia is caused by a sudden interruption of cerebral circulation from cardiac or extracardiac causes. The main question that should be answered in the process of investigating a syncope episode is whether it is due to cardiac or extracardiac causes, since the prognosis of patients with syncope due to organic heart disease may be poor.
What are the causes of syncope?
1. Neurocardiogenic syncope
a. Vasoparasympathetic syncope (Common Fainting): It is the most common cause of syncope due to a drop in blood pressure due to abnormal vasodilatation, reflexively caused by emotion, fear or anxiety.
Precursor symptoms such as nausea, epigastric heaviness, dizziness, blurred or impaired vision appear before syncope (may precede several minutes before)
b. Orthostatic: Hypotension caused by a drop in pressure in the upright position due to stasis of blood in the lower extremities and loss of cardiovascular reflexes. It occurs when the body is leveled.
c. Occasional: Occasional syncope is essentially vasoparasympathetic syncope caused by a specific activity (coughing, urinating, swallowing, etc.).
2. Cardiac causes
a. Arrhythmias: Ventricular tachycardia, ventricular fibrillation, atrioventricular block (Adams-Stokes syndrome), large sinus bradycardia, sick sinus syndrome, carotid sinus syndrome.
b. Mechanical cardiac causes: Aortic stenosis, left atrial myxosis, or hypertrophic cardiomyopathy.
3. Neurological causes
a. Transient ischemic strokes
b. Epilepsy
The diagnosis can be made from the history, clinical examination, laboratory findings and electrocardiogram. If the diagnosis is not possible from these tests, the following are additionally performed: Triplex of the heart and carotid arteries, fatigue test, 24-hour heart holter, CT or magnetic resonance imaging of the brain, electroencephalogram and electrophysiological study of the heart, which helps to discover and evaluate possible arrhythmic causes.
