Class IV: Cardiogenic shock. Hypotension (a systolic blood pressure of less than 90 mmHg for at least 30 minutes or the need for supportive measures to maintain a systolic blood pressure of greater than or equal to 90 mmHg), end-organ hypoperfusion (cool extremities or a urine output of less than 30 ml/h, and a heart rate of greater than or equal to 60 beats per minute). The hemodynamic criteria are a cardiac index of no more than 2.2 l/min per square meter of body-surface area and a pulmonary capillary wedge pressure of at least 15 mmHg. Signs include hypotension (systolic pressure < 90 mm Hg) and evidence of peripheral vasoconstriction such as oliguria, cyanosis and diaphoresis. Heart failure, often with pulmonary oedema, has also been present in the majority of these patients.