Transient Loss of Consciousness

Transient loss of consciousness is a condition where one individual momentarily lose his/her consciousness and regains his/her full consciousness within few seconds or minutes without any remaining disability.

Loss of consciousness is a serious condition and causes lot of discomfort and trouble to individuals and occasionally can be fatal. There are multiple causes of loss of conscious ness but in general if the loss of consciousness is due to any heart condition then it is transient  and the episode lasts only for few seconds to minutes. Patient recovers quickly to normal self after the episode of unconsciousness. These episodes can be associated with sweating, palpitation and chest discomfort.

To maintain our consciousness brain requires constant blood supply. Our heart pumps blood to the brain and heart generally pumps at a rate of 60 – 100/min to maintain the adequate blood and oxygen supply to the brain. Heart has an automatic generator (SA Node,which produces electricity) and wiring system to conduct electricity. With advancing age or because of any other causes if the generator (SA node) malfunctions or the wiring system cannot conduct the electricity properly from the upper chamber to the lower chambers of the heart then heart rate drops. Once heart rate drops significantly low it cannot cope to supply adequate blood and oxygen to the brain and a person can become unconscious quickly.

Apart from slow heart rate very fast heart rhythm (Ventricular tachycardia or ventricular fibrillation – heart starts beating at a rate around 250- 300/min and fail to generate effective pressure to send blood to the brain) can also produce episodes of unconsciousness and sometimes can be fatal. This fast heart rhythm happens in conditions where heart muscle is already damaged either from a previous heart attack or from heart muscle disease (cardiomyopathy) and sometimes from some genetic heart rhythm problems. Some of the medicines can also precipitate very fast heart rhythm problem which can be fatal.

Sometimes blood pressure regulatory problem can also give rise to transient loss of consciousness. Generally our blood pressure drops once we stand up from lying down position; this drop in normal individual is never above 10 mm Hg.  In some persons particularly in elderly individuals this drop can be more than 20 mm Hg causing inadequate blood supply to the brain causing transient loss of consciousness. In some individual heart rate also drops precipitously while standing up from lying position. These conditions are known as ‘neurocardiogenic syncope’.

In some individual fainting attack can be situational e.g extreme emotional outburst, sight of blood or needle prick etc. This often happens in young individuals. This is known as ‘vasovagal attack’ or ‘simple faint’