Inotropic agents

Inotropic agents are a group of medicines that affect the contraction of the heart muscle. Technically, inotropes can be divided into positive inotropes, which stimulate and increase the force of contraction of the heart muscle, and negative inotropes, which weaken the force of muscular contractions, decreasing how hard the heart has to work. However, clinically, if the word inotrope is used it typically refers to positive inotropes.

Inotropes are given for conditions associated with a low cardiac output (CO) (poor heart contraction), such as cardiogenic shock following a heart attack, severe heart failure, or following cardiac surgery. If left untreated, tissues become starved of oxygen, resulting in the formation of lactic acid and subsequent organ failure and death. Most positive inotropes work by increasing the release of calcium from the sarcoplasmic reticulum or increasing the influx of calcium into the heart muscle cell.

Initial monitoring of hemodynamic parameters such as cardiac output, arterial pressure, and central venous pressure is required on initiation of a positive inotrope. Preference for one inotrope over another has not been established.