Sinus node dysfunction or atrioventricular blocks are the causes of bradycardias. Diagnosis and management begin with evaluation of patient's hemodynamic status and diagnosis of bradycardia's cause. This is followed by an in depth evaluation of pathophysiology of the arrhythmia, its severity, and likelihood of progression. Implementing emergent measures depends on the presence of subsidiary pace makers maintaining cardiac output. Many of these decisions are greatly helped by 12 lead electrocardiogram, because its tracings are often diagnostic of the cause of the bradycardia and help to assess its persistence and progression and to evaluate the presence and reliability of subsidiary pacemakers.