In general, loss of synchronous atrial contraction can reduce cardiac output by 20% to 30%, or more than 50% in cases of pre-existing cardiac insufficiency; atrioventricular valve insufficiency causes systolic regurgitation of blood back into the atria, increasing atrial load; increased atrial pressure inhibits the normal contractile reflex of the peripheral vasculature, leading to a decrease in blood pressure; right ventricular pacing leads to biventricular contraction asynchrony; ventricular atrial electrical activity of the ventricles Reverse conduction of ventricular electrical activity can lead to an increase in pacing frequency. What can we do to prevent increased pacing frequency? Pacemakers implanted before 1985 had a high incidence of pacemaker syndrome (4.6%) because of their non-selective pacing mode. Pacemaker syndrome can be prevented by performing a simple electrophysiological and hemodynamic examination before placing a permanent right ventricular pacemaker to find the most appropriate pacing frequency and pacing mode; by avoiding permanent pacing in patients with atrial retrograde transmission during temporary right ventricular pacing, especially in patients with pathological sinus node syndrome; and by using physiological pacing as much as possible. However, the possibility of pacemaker syndrome is not excluded in cases of double-chamber pacemakers with markedly delayed left atrial excitation and excessive A-V interval programming. Pacemaker syndrome refers to a group of clinical syndromes caused by hemodynamic and electrophysiological abnormalities after pacemaker implantation. In patients receiving VVI pacing, a decrease in blood pressure of more than 20 mmHg immediately after implantation indicates that pacemaker syndrome is likely and that a dual-chamber pacemaker should be implanted.