Symptoms - Dizzy Spells/Blackouts

There are many causes of dizziness and loss of consciousness (blackouts), and usually these symptoms are not a sign of serious heart disease. Nevertheless they are important symptoms and should not be ignored, particularly if recurrent or associated with injury, or in patients known to have heart disease such as a previous heart attack, or where there is a family history of premature sudden death.

Many people, especially children and young adults, are prone to simple faints which are completely benign. These episodes often occur at times of stress or in hot stuffy surroundings, or at times of dehydration. Usually no treatment is required, other than being aware of and avoiding triggers.

Less commonly abnormal heart rhythms or problems with the structure of the heart may be responsible, and for this reason recurrent symptoms should prompt medical review. Either fast or slow heart beats may cause dizziness or blackouts. The medical term for fast heart beats is tachycardia, and for slow heart beats bradycardia. Taking a careful history of the episodes, clinical examination, and a few simple tests often allows a rapid diagnosis to be made and effective treatment to be recommended. The tests may include recording the heart rhythm, and sometimes an ultrasound scan of the heart. If the symptoms are relatively infrequent more prolonged monitoring may be necessary, and this might include the use of an implantable monitor. See investigations section, implantable loop recorder. Treatments may include medications, a cauterising procedure for treating fast heart beats, or a pacemaker for symptoms caused by a slow heart beat.

Very rarely blackouts may be caused by dangerous disturbances of heart rhythm or be a sign of important heart valve problems. Effective treatments are available and therefore it is essential that these conditions are recognised early.

Sometimes tests on the heart do not reveal any abnormality and other investigations, such as neurological tests, may be needed to arrive at the correct diagnosis.