**11. Indications for mechanical circulatory support**

Before we cite specific indications for IAB insertion, we should discuss indications for mechanical circulatory support. In other words, we should be able to delineate or define ventricular failure. LV failure would be defined as cardiac index (CI) of less than 1.8 L/min/m² with a systolic blood pressure of less than 90 mmhg (ref: Hensley Martin) despite maximized preload (mean atrial pressure > 20 mmhg), optimized heart rate (> 80) and normalized ionized calcium. This could be extrapolated to RV failure except for the systolic blood pressure. RV work is the function of the difference between the RA and PA mean pressure. As the difference between the two approaches zero, pulmonary blood flow is passive and RV failure is present. RV failure can occur with or without pulmonary hypertension.

Mechanical support is suggested when the above criteria are present despite maximum inotropic support. Maximum inotropic support can be defined as any two or more (*High et al., 1995*) of the following combinations:


For patients with severe forms of LV failure, ventricular assist devices (VAD) are indicated. The initial indicated mechanical support in these scenarios is the IABP. Large and prolonged inotrope infusion will only tend to increase the workload of the ventricle. The IABP does the exact opposite, decreases the workload of the heart.
