Recognition and treatment of cardiogenic shock.

Cardiogenic shock has long been a difficult problem for clinicians. The most common cause is left ventricular pump failure after myocardial infarction, but other important causes include mechanical complications of infarction, right ventricular dysfunction, prolonged cardiopulmonary bypass, valvular disease, and cardiomyopathy. Cardiogenic shock is the leading cause of in-hospital death after myocardial infarction. Despite advances in management of heart failure and acute myocardial infarction, clinical outcomes had remained frustratingly poor, with reported mortality rates ranging from 50 to 80%. Recently, however, survival rates have been improving. Improved understanding of the pathophysiology of cardiogenic shock has led to renewed emphasis on the notion that stunned or hibernating myocardium may recover function with hemodynamic support and restoration of flow. This concept has underscored the importance of expeditious initiation of supportive measures to maintain blood pressure and cardiac output, including both medications and intraaortic balloon counterpulsation. Finally, the theory that coronary revascularization would be beneficial by reversing the vicious cycle in which ischemia causes myocardial dysfunction, which in turn worsens ischemia, which had been supported by an extensive body of observational and registry studies, has now been strongly buttressed by the results of two randomized, controlled trials, both of which show improved mortality with early revascularization for cardiogenic shock in the setting of acute infarction.