Syncope is a partial or complete loss of consciousness with possible interruption of awareness of oneself and their surroundings. When the loss of consciousness is temporary and there is spontaneous recovery, it is referred to as syncope, or in nonmedical terms, fainting. Syncope accounts for one in every 30 visits to an emergency room. It is pronounced sin-ko-pea.
Syncope is due to a temporary reduction in blood flow and therefore a shortage of oxygen to the brain. This leads to lightheadedness or a "black out" episode, a loss of consciousness. Temporary impairment of the blood supply to the brain can be caused by heart conditions and by conditions that do not directly involve the heart.
Some non-cardiac causes of syncope could be:
Fainting after certain situations (situational syncope) such as:
Or anything that would trigger a reflex of the involuntary nervous system that slows the heart and dilates blood vessels in the legs and causes one to feel nauseated, sweating, or weakness just before fainting.
A migraine attack
A brain stroke or "near stroke" (transient ischemic attack)
Blood pressure medications leading to low blood pressure
Dehydration causing a decrease in blood volume
Postural hypotension or a drop in blood pressure due to changing body position to a more vertical position after lying or sitting.
Some cardiac causes could be:
- Abnormal heart rhythms (the heart beating too slow or too fast)
- Abnormalities of the heart valves (aortic stenosis)
- High blood pressure in the arteries supplying blood to the lungs (pulmonary artery hypertension)
- Tears in the aorta (aortic dissection)
- Widespread disease of the heart muscle (heart failure or cardiomyopathy)