Syncope, or fainting, is an abrupt and short-lived loss of consciousness. It is a common problem, requiring the evaluation of more than 1 million cases per year in the US. Syncope accounts for more than 10 percent of falls, and therefore, is capable of causing serious injury. Typically, patients recover quickly and completely. Episodes may or may not be marked by warning signs or symptoms. At Lahey Clinic, consultation is often sought with a cardiac electrophysiologist, a cardiologist who focuses on the evaluation and treatment of heart rhythm disturbances. In addition, a specialized heart center like Lahey's Heart & Vascular Center offers access to physicians who are skilled in the performance of diagnostic testing and corrective procedures.
Diagnosis can often be made clinically, that is, without the use of specialized tests. There are many causes of syncope, most commonly disturbances of heart rhythm or blood pressure. The likelihood of a serious arrhythmia, or abnormal heart rhythm, depends on whether underlying heart problems are present. Most importantly, in patients who have a damaged heart muscle but otherwise possess no symptoms, syncope can predict the possibility of dying suddenly from a lethal arrhythmia, or cardiac arrest. Ninety percent of syncope patients may never have a second episode, regardless of treatment.
Essential to the evaluation of syncope is a thorough review of a patient's medical history and a physical examination. In addition, descriptions of the event by the patient and witnesses are also critical to diagnosis. Following the patient and witness interviews, a physical examination is performed to check for evidence of heart or vascular disease. Non-invasive testing is then completed and may include an electrocardiogram to assess the heart rhythm; an echocardiogram to image the heart muscle; and a stress test to look for significant coronary artery blockages. A very common type of syncope involves a nervous reflex in which the heart rate becomes quite slow and the blood pressure very low for seconds or minutes. Electrophysiologists can use a test referred to as a tilt table test to mimic these episodes and make a proper diagnosis. However, this is often still less valuable than a thorough interview and examination by a medical specialist who is experienced with syncope.
Although invasive testing is not needed in the case of many syncope patients, consideration for more extensive testing is given to patients with significant heart disease. For example, an invasive test called an electrophysiology study (EP study) may be performed. During this procedure, the cardiac rhythm is analyzed to better understand the cause of syncope, as well as to determine appropriate treatments. Abnormally slow or fast heart rhythms may be discovered. These rhythms often require the implantation of a heart device such as a permanent pacemaker (PPM) or an internal cardioverter-defibrillator (ICD). A pacemaker is a device that can correct a slow, unreliable heart rhythm, whereas an ICD detects and treats dangerous, abnormally fast rhythms.