Other heart conditions may cause dizziness even when the heart is in normal rhythm. These include problems with the heart valves (narrowing or leaking) and problems with the pumping function of the heart. Such conditions can usually be discovered with physical examination, an electrocardiogram, and an ultrasound examination of the heart (an echocardiogram). In some cases, more invasive testing is required.
A nervous reflex involving the heart is a common cause of dizziness and syncope. These neurocardiogenic reflexes have many causes, but all result in some combination of relaxation of the blood vessels and slowing of the heart rate, which in turn causes low blood pressure and dizziness or fainting. The reflexes are usually transient and the chief concern lies in the potential for physical injury caused by loss of consciousness. These spells may be triggered by certain stimuli, such as coughing, swallowing, straining, pain, or fright, or they may occur for no apparent reason. When the symptoms are very typical, no further testing is needed; in less certain cases, a doctor may recommend tilt table testing, in which a patient is tilted upright on a table for 30 to 40 minutes while the heart rate and blood pressure is monitored.
This is a long answer to a simple question, but it illustrates why it is often difficult to find a definite cause of dizziness in a given patient. You can help your doctor by making note of any associated feelings you have when you become dizzy, the circumstances during which dizzy spells occur, and also by measuring your pulse rate during an episode.
