Symptoms of sinus bradycardia, according to the degree of occurrence of all the differences, as follows: 1, mild sinus bradycardia without obvious symptoms, some will appear dizziness or activity with insufficient blood supply and other performance; 2, sinus bradycardia, slow heartbeat, can appear important organ function deficiencies; 3, with organic heart disease, there will be angina and other symptoms; 4, insufficient blood supply to the brain can occur dizziness, syncope, and even A – S syndrome or sudden death.