Some people experience fainting and near fainting episodes. These episodes can be caused by many conditions. Most of these episodes are associated with dizziness, sweating and fast heart beat. The medical term used for fainting is syncope. The most important information your doctor will need to know in order to diagnose these conditions is the description of the situation in which you had the episode. Were you standing at the moment? Or you were walking through the mall? What were the associated symptoms? Can you improve the symptoms by lying flat? Etc.
I will try to briefly describe each cause of fainting and near fainting episodes:
This can be caused by a disease in the heart valves which is blocking the blood flow out of the heart to the brain. There are some other less common conditions that may block blood flow out of the heart and cause you to faint such as enlargement of the heart muscle blocking the heart outlet. Also, cardiac syncope may be due to a disease in the heart muscle itself affecting heart's ability to pump sufficient amounts of blood to perfuse the brain. The above two types of syncope tend to happen while standing or walking but rarely while lying or sitting. Cardiac syncope can be caused by arrhythmias. Arrhythmia means your heart is beating irregularly faster or slower than usual. This type of syncope may occur in any position. Arrhythmia is diagnosed by recording it on ECG or on 24-hours Holter monitor. Syncope may also result from an acute myocardial infarction which is an emergency that is usually associated with severe chest pain, nausea and sweating.
Reflex or vasovagal syncope
This is the most common type of syncope in young adults but actually it can happen at any age. It usually occurs in a standing position and is mediated by emotional distress or physical pain, even mild pain may cause this type of syncope (after injection). The most common symptoms associated with this are nausea, sweating and light-headedness.
This is diagnosed if you faint whenever you do specific action such as micturition or swallowing. Situational syncope has basically the same mechanism as vasovagal syncope but related to specific identified events that's why the first line for treatment is avoiding these events, and some protective maneuvers when it is not possible to avoid the event.
Syncope due to sudden drop of blood pressure when standing up is called orthostatic hypotension. Many medical conditions can cause orthostatic hypotension but the most common one is dehydration due to insufficient oral fluid intake, diarrhea, vomiting or using water pills (diuretics).
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