[Syncope and fainting in patients with a cardiac pacemaker]

When a patient with a cardiac pacemaker presents with syncope or faintness, one's first thought should be failure of the pacemaker. If the abnormality is not apparent, the patient needs a full cardiological investigation, including "active" electrocardiographic recordings: magnet test, programming, or even Holter monitor should be performed in order to exclude the responsibility of the pacemaker. Modern pacemakers can fail and cause syncope, especially if they have been inadequately or incorrectly regulated. The so-called physiological (double chamber) pacemakers can induce dangerous arrhythmias. Programming of the pacemaker can avoid further operation and can relieve the syncope: acceleration to prevent twisting of the apex, increase in the power of the impulses to eliminate the defects in stimulation due, for example, to a rise in the threshold. The syncope may also be caused by an extracardiac cause: associated pathology or useless implantation; the simplicity of implantation techniques sometimes means that pacemakers are implanted in inappropriate cases.