Cardiac emergencies are life-threatening conditions that must be diagnosed quickly to avoid delay in treatment and to minimize morbidity and mortality. Cardiac emergencies represent most feared complications because of their complex pathogenesis. The successful management requires accurate diagnosis and timely interventions to achieve optimal outcome. This chapter covers the cardiac tamponade, cor pulmonale, pulmonary edema, cardiogenic shock, and cardiac arrest along with their etiology, pathophysiology, clinical manifestations, diagnostic evaluation, and management. Cardiac tamponade or pericardial tamponade is a true medical emergency. It can cause life-threatening complication due to rapid accumulation of fluid in the pericardial cavity. Acute pulmonary edema is the most important medical emergency. It is a local edema with serious functional impairment. It is most frequently seen with left ventricular dysfunction.