At some stage in most people’s lives, they will experience dizziness or a blackout. Dizziness and blackouts can be caused by a number of different problems, which can be related to the heart, blood pressure, the inner ear, the nervous system and brain, or blood related problems. Identifying the cause is key to treating patients.
Dizziness and Light-headedness
When patients report that they have dizzy episodes, the symptom can mean quite different things to different people. To some people, dizziness means that they feel light-headed and feel that they may pass-out. Others mean that they have symptoms that are more consistent with vertigo. Vertigo is caused by a problem in the inner ear, in which the surroundings start moving when there is no actual movement. This can also make people feel nauseated or even vomit. It also causes problems with balance and falling over. Dizziness may occur at any stage in life, but it is more common in older people.
Dizzy episodes and light-headedness can be caused by a number of different problems. Many of us will have had an episode in which we have stood up quickly having been sitting down for a while, and transiently feel dizzy or light-headed. This usually very rapidly passes, and is most commonly caused by a transient drop in blood pressure. There are a group of patients that suffer with this symptom every time they stand up, and this may be due to a problem with the part of the nervous system that regulates blood pressure. Ensuring that you are well hydrated and have an adequate amount of salt in your diet can help with this. We should all be drinking around 2-3 litres of water every day. With modern diets it is difficult to avoid salt, and usually does not require any additional salt to be added to food to help the problem. It can also be the result of persistently low blood pressure, which might be due to over-treatment with medications to lower blood pressure in a person that usually has high blood pressure.
Dizziness and light-headedness can also be caused by problems in the blood. One of the more common reasons is anaemia. In order to result in these symptoms the haemoglobin level is generally quite low. There are many different causes for anaemia, and this should be investigated to determine the correct treatment.
The same symptoms can also be caused by problems with the heart. These can more commonly be heart rhythm problems or heart valve problems. Some heart rhythm problems are that the heart is beating too slowly, or that the electrics of the heart is not sending the messages correctly. In other instances, it could be that the heart is going to quickly and has gone out of its normal rhythm (sinus rhythm) into an arrhythmia (abnormal heart rhythm). Heart valve problems might also cause similar symptoms. If the valve is too narrow or tight, not enough blood is able to pass through the valve. It is also possible that there is a very leaky heart valve, in which blood flows back the wrong way through the valve.
The brain and nerves of the body have important roles in regulating blood pressure and heart rate. This part of the nervous system is called the automonic nervous system. If there are problems with the autonomic nervous system, dizziness and light-headedness can also result.
What causes blackouts and feinting?
All of the problems that are described above can result in blackouts and feinting. Commonly, a vasovagal reaction is the cause of feinting. This is a transient problem with the autonomic nervous system, and is extremely common. Common causes of vasovagal syncope are pain, emotional stress, and sight of blood.
In instances of severe narrowing of the heart valves there is not enough blood passing through the valve to meet the demands of the body. Typically the aortic valve which is on the left side of the heart (the valve that is between the left ventricle and the aorta) is the valve of concern. Narrowing of the aortic valve is called aortic stenosis. When the valve is significantly narrowed (stenosed), the supply of blood through the valve to the vital organs such as the brain is not enough. The result is that patients can collapse and loose consciousness.
Other patients may have a blackout or feinting episode due to a heart rhythm problem. As previously mentioned this might be due to a fast or a slow heart beat. Fast heart beats could be an arrhythmia, in which the heart has gone out of its normal rhythm. It may also be due to the heart beating too slowly. This may be while it is in the normal rhythm, an abnormal rhythm, or a type of ‘heart block’ in which the electrical messages that are sent around the heart become disrupted.
What is bradycardia?
Bradycardia is where the heart is beating too slowly. If the heart rate is lower than 60 beats per minute, it is termed bradycardia. This is not always a problem. For example, some people that are physically very fit can have a resting heart rate of 40 beats per minute. In this situation, and without any symptoms, it may be of no concern. Similarly, some patients are not physically very fit, and have a persistently low heart rate that doesn’t increase when they exercise. This can cause dizziness or light-headedness, and may require a pacemaker in some instances. The heart can also go out of its normal heart rhythm, and run slowly.
What is tachycardia?
Tachycardia is where the heart is beating quickly. If the heart rate is above 100 beats per minute, this would be classified as tachycardic. This is not necessarily abnormal, for example when exercising. In this situation you would expect the heart rate to increase, and if it is in the normal rhythm this is referred to a sinus tachycardia.
Tachycardia can also occur when the heart is not in the normal heart rhythm, termed an arrhythmia. There are different types of arrhythmia, which can originate in the top chambers of the heart (atria) or the lower chambers of the heart (ventricles). In addition, there can be extra electrical connections which people are born with. These can also be implicated in causing arrhythmia.
When the heart is beating very quickly in an tachy-arrhythmia (fast and abnormal heart rhythm), the normal function of the heart is disrupted. This can result in people feeling dizzy or light-headed and a feeling that you might feint. Some tachy-arrhythmias can cause people to black out, but this is less common.
What is heart block?
There are different types of heart block. Heart block refers to a slowing of the electrical conduction through the heart. The different types of heart block relate to the different regions of the heart’s electrical conduction system that can be affected. Some types of heart block do not need any specific treatment, and can simply be monitored. Other types of heart block may require treatment with a pacemaker.