The main diseases treated by permanent pacemakers include severe atrioventricular block, sinus node dysfunction, and other heart conditions. Permanent pacemakers stimulate the heart by sending certain electrical impulses that cause the heart to excite and contract, mimicking normal heart conduction. Specific diseases treated include: 2nd or 3rd degree atrioventricular block; sinus node dysfunction with symptomatic medication that is ineffective; atrial flutter or atrial fibrillation with high or complete atrioventricular block and a ventricular rate of <40 beats per minute; carotid sinus hypersensitivity with a slow heart rate with syncope occurring; and sinus rhythm that cannot be restored in 3 weeks after treatment with a temporary pacemaker. After surgery, the pulse rate should be monitored regularly, and if the pulse rate is found to be 10% less than before, the patient should be seen promptly and treated according to the doctor's instructions.