Important mechanisms of syncope
What are the three main mechanisms of syncope?
- Orthostatic hypotension may be due to a reduction in vascular resistance, hypovolemia, drugs, chronic baroreflex failure, or a neurally mediated mechanism (vasovagal syncope triggered by pain or fear). Reflex syncope and vasodepressor syncope are synonymous with vasovagal syncope.
- Fall in cardiac output may be due to cardiac arrhythmias, obstructions to flow, or myocardial infarction.
- Increased cerebrovascular resistance may be due to hyperventilation or increased intracranial pressure.