Shock, cardiogenic: Shock due to low blood output by the heart, most often seen in conjunction with heart failure or heart attack (myocardial infarction). In cardiogenic shock, the heart fails to pump blood effectively. For example, a heart attack (myocardial infarction) can cause an abnormal, ineffectual heartbeat (arrhythmia) with very slow, rapid, or irregular contractions of the heart, impairing the heart's ability to pump blood and lowering the volume of blood going to vital organs. Cardiogenic shock can also be due to drugs that reduce heart function or an abnormally low level of oxygen in the blood (hypoxemia) that may be caused, for instance, by lung disease. Whatever the cause of cardiogenic shock, the blood vessels constrict, and adrenaline-like substances are secreted into the bloodstream, increasing the heart rate. Treatment of cardiogenic shock is aimed at improving the heart's function. Cardiogenic shock is extremely serious. The mortality rate is over 80 'percent.