A rare, cardiac condition characterized by severely decreased cardiac output, hypoperfusion and end-organ dysfunction, in the presence of adequate intravascular volume. The clinical presentation is variable and may range from subtle hemodynamic alterations to overt cardiovascular collapse. Commonly reported features include dyspnea, crackles, elevated jugular venous pressure, altered mental state, abnormal pulse pressure, oliguria, cold extremities, and increased serum lactate levels.