Syncope is the loss of consciousness caused by a decrease in the amount of blood that flows into the brain. It can happen suddenly, and it is characterized by short duration and spontaneous recovery. Syncope can happen due to changes of the blood flows to different body areas. It can also happen as a result of a sudden drop in heart rate or blood pressure.
Some of the symptoms that occur before the onset of syncope are:
Syncope can be caused by overheating, exhaustion, dehydration, muscle strain, heavy sweating, or standing for a long period of time. Medical conditions (e.g. of the nervous and cardiovascular systems) can also trigger syncope. Some other medical conditions cause the decrease of blood pressure, which affects the blood flow through the body. A change a position can cause syncope, e.g. standing after lying down, moving from side to side.
Vasovagal syncope (also known as cardio-neurogenic syncope)
Vasovagal syncope is caused by a rapid drop in blood pressure and deprivation of oxygen to the brain. It happens due to position change, for example; standing up. When the sitting person stands, the blood tends to remain in the lower part of the human body due to gravity. Within less than a minute the autonomic nervous system, and the cardiovasuclar system stabilize the blood pressure. Vasovagal syncope is the most common type of syncope.
Situational syncope is usually considered a type of vasovagal syncope triggered under certain circumstances. These situations can have a direct effect on the nervous system, leading to a sudden faint.
These situations include
A sudden or a quick movement can cause this type of syncope. It can also be caused by the use of certain medication, or by dehydration. Postural syncope can be a symptoms of other illnesses such as structural heart disease, unorganized heart beat, valve disease, blood clot, heart failure, or blockage in blood vessels of the heart.
A transient ischemic attack, a stroke, or a seizure can cause Neurologic syncope. Migraines and normal pressure hydrocephalus are less common causes of Neurologic syncope.
Postural Orthostatic Tachycardia Syndrome
Usually, women suffer from this condition more than men. It is caused by an increase in the heart rate (by 30 beats per minute or more). This quickening happens when the patient stands up after lying down for several hours.
Doctors employ a number of tests to diagnose a patient with syncope: Exercise stress test: in order to measure the heart rate. Ambulatory monitor: also to measure the heart rate over the course of normal living. Electrocardiogram (EKG or ECG): record heart activity. Blood tests (anemia or metabolic imbalances) Echocardiogram: a test that uses high-frequency sound waves to examine heart structures. Autonomic reflex testing: a number of tests to diagnose the heart, blood pressure, and flow, and the temperature of the skin. Hemodynamic testing: this test is to examine the blood flow and the pressure inside the cardiac blood vessels. Tilt table test: this test can be useful when prior diagnosis shows no heart problems. The patient lies on a table, and moves to different positions while heart rhythms and blood pressure are measured.
Medications: Fludrocortisone acetate, or Selective serotonin inhibitors are sometimes prescribed.
Therapies: doctors may suggest exercises to improve the flow of blood in the upper body. Doctors also recommend patients avoid salt, refrain from standing for long periods of time, and drink plenty of fluids.
Surgery: this is not done just for syncope, but implantation of electrical pacemakers can help with blood distribution.
Presyncope is the "prodrome" of syncope. It doesn't entail fainting, but subjects report feeling that they are on the verge of fainting. Tt is also called near-syncope.