Septic shock is the major cause of death in ICU patients and sepsis-induced cardiovascular dysfunction accounts for most of the sepsis-induced mortality. Cardiac abnormalities during septic shock in humans is poorly understood. To further define the heart's response to sepsis, serial hemodynamic studies and simultaneous radionuclide angiography were performed in patients with septic shock. This allowed construction of Starling ventricular function curves in order to assess myocardial response to volume infusion in these patients. Patients with septic shock demonstrated two distinct types of abnormalities of left ventricular function: (1) some patients failed to develop ventricular dilatation in response to a pressure increase, indicating a compliance abnormality of the ventricle; (2) others failed to increase stroke work despite an appropriate increase in ventricular volume, indicating a contractility abnormality. Further definition of these abnormalities of myocardial function should lead to more effective treatment of this highly lethal syndrome.