From the Guidelines
Syncope can be caused by various factors, including cardiac, neurological, and metabolic disorders, as well as situational and psychiatric conditions. The most common cause of syncope is vasovagal syncope, which is triggered by emotional stress, pain, or prolonged standing, and is characterized by a sudden drop in heart rate and blood pressure 1. Other cardiac causes of syncope include arrhythmias, such as bradycardia, tachycardia, or heart blocks, as well as structural heart problems, such as aortic stenosis or hypertrophic cardiomyopathy 1. Neurological causes of syncope include seizures, transient ischemic attacks, and migraines, while situational syncope can occur during specific activities like coughing, urinating, or swallowing 1. Metabolic disorders, such as hypoglycemia, hypoxia, or anemia, can also reduce oxygen or glucose delivery to the brain, leading to syncope 1. Psychiatric conditions, like panic attacks or anxiety disorders, may also present with syncope-like episodes 1. Some of the other causes of syncope include:
- Infectious causes, such as myocarditis, Lyme disease, and Chagas disease 1
- Neuromuscular causes, such as myotonic dystrophy, Friedreich ataxia, and Kearns-Sayre Syndrome 1
- Anatomic causes, such as Lenègre-Lev disease, cardiac tumors, and prosthetic valve thrombosis 1
- Endocrine causes, such as carcinoid syndrome, pheochromocytoma, and mastocytosis 1
- Hematologic causes, such as beta thalassemia major 1
- Neurological disorders, such as seizure-induced bradycardia/hypotension and migraine 1 Proper diagnosis requires a thorough medical history, physical examination, and sometimes specialized tests like electrocardiograms, echocardiograms, or tilt-table testing to determine the underlying cause and guide appropriate treatment 1. It is essential to note that the evaluation and management of syncope should be guided by the patient's clinical presentation, medical history, and risk factors, rather than relying solely on diagnostic tests 1. In patients with syncope or presyncope, a detailed history and physical examination should be performed to identify potential causes and guide further evaluation and management 1. The use of imaging studies, such as head CT or MRI, should be reserved for patients with specific indications, such as trauma, focal neurological deficits, or suspected stroke 1. Similarly, cardiac imaging studies, such as echocardiography or cardiac MRI, should be used to evaluate patients with suspected cardiac causes of syncope, such as arrhythmias or structural heart disease 1. By taking a thoughtful and targeted approach to the evaluation and management of syncope, healthcare providers can improve patient outcomes and reduce the risk of adverse events.
From the Research
Causes of Syncope
The causes of syncope can be categorized into several types, including:
- Cardiovascular causes, which can be further subdivided into:
- Non-cardiovascular causes, which include:
- Unexplained causes, which may be due to neurally mediated (neurocardiogenic or vasovagal) syncope 4, 6
Specific Causes of Syncope
Some specific causes of syncope include:
- Orthostatic hypotension, which can be caused by an impairment of peripheral vasoconstriction or a reduction of the intravascular volume 4
- Neurocardiogenic or neurally mediated syncope, which can be associated with painful or emotionally stressful situations, prolonged standing, or specific trigger situations such as micturition, defecation, coughing, or sneezing 4
- Vascular causes, such as pulmonary embolism, subclavian steal, aortic dissection, cerebrovascular disease, intracerebral hemorrhage, carotid/vertebral dissection, and abdominal aortic aneurysm 5, 3
- Cardiac causes, such as cardiac arrhythmia, ischemic heart disease, and structural impairment of the heart or arteries 2, 3
Classification of Syncope
Syncope can be classified into three major types: