Pacemaker syndrome refers to a group of clinical syndromes caused by hemodynamic and electrophysiological abnormalities after pacemaker implantation. It can occur in any pacing mode as long as the atria are separated. It is usually seen in VVI (suppressed on-demand ventricular) pacing mode mainly manifested by neurological symptoms of low cardiac output and congestive heart failure. What are the diagnoses of diseases associated with increased pacing frequency? Syncope occurs in about 38% of clinical cases Epidemiology: Pacemaker syndrome occurs in about 17% to 38% of patients with implanted ventricular pacemakers Syncope occurs in about 38% of patients with implanted single ventricle pacemakers, mostly due to clinical syndromes caused by asynchronous atrioventricular contraction, ventriculoatrial block and elevated right atrial pressure caused by implanted single ventricle pacemakers. The main prerequisites for establishing the diagnosis of pacemaker syndrome are that the patient develops symptoms after placement of a VVI artificial pacemaker; that the pacemaker functions normally; that there are hemodynamic abnormalities during cardiac pacing, such as decreased blood pressure and stroke volume and increased venous and pulmonary insertion pressure; and that the symptoms are reduced or disappear when self rhythm is present. The basic frequency of stimulation pulses issued by the pacemaker is based on the patient’s needs. Generally, 70 to 90 beats/min is the optimal heart rate, and the pacing frequency should be greater than 10% of the patient’s own heart rate. Pacemaker syndrome is a group of clinical syndromes caused by hemodynamic and electrophysiological abnormalities after pacemaker implantation. It can occur in any pacing mode as long as there is atrial separation. It is usually seen in the VVI (suppressed on-demand ventricular) pacing mode. The main manifestations are neurological symptoms, low cardiac output and congestive heart failure.