**6. Contractility**

Contractility is defined as the change in the force of contraction, independent of myocardial fiber length. Contractility inotropic performance can be increased by endogenous production of catecholamines or exogenous administration of vasopressors like norepinephrine (NE), dopamine, calcium etc. Myocardial contractility decreases wuth hypoxemia and drugs like barbiturates, procainamide, lidocaine, propranolol etc.
