The pacemaker delivers the basic frequency of stimulation pulses according to the patient’s needs. Generally, 70 to 90 beats/min is the optimal heart rate, and a pacing frequency greater than 10% of the patient’s own heart rate is appropriate. 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. Syncope occurs in approximately 38% of clinical cases. Etiology of increased pacing frequency 1. Loss of atrial synchronous contraction can reduce cardiac output by 20% to 30%, or more than 50% in cases of pre-existing cardiac insufficiency; 2. Atrioventricular valve insufficiency causes systolic blood to regurgitate back into the atria, increasing atrial load; 3. Increased atrial pressure inhibits the normal contractile reflex of peripheral vessels, resulting in a drop in blood pressure; 4. Right ventricular pacing results in biventricular contraction asynchrony; 5. 5. Reverse ventricular-atrial conduction of electrical activity in the ventricles, atria, etc. Pacemaker syndrome can be prevented by performing a simple electrophysiological and hemodynamic examination prior to the placement of a permanent right ventricular pacemaker to find the most appropriate pacing frequency and pacing rate. Avoid permanent pacing in patients with atrial retrograde transmission during temporary right ventricular pacing, especially in patients with pathologic sinus node syndrome, and use physiologic pacing whenever possible. In patients with VVI pacing, a decrease in blood pressure of more than 20 mmHg after implantation indicates a high probability of pacemaker syndrome, and a dual-chamber pacemaker should be implanted, but the possibility of pacemaker syndrome cannot be ruled out in cases of significantly delayed left atrial excitation or excessive A-V interval control with a dual-chamber pacemaker.