American Association of Critical-Care Nurses (AACN) Certification Practice Test

What is the primary effect of a positive inotrope?

1. Decrease heart rate

2. Increase myocardial contractility

3. Decrease myocardial contractility

4. Decrease cardiac output

The correct answer is: Increase myocardial contractility

A positive inotrope primarily increases myocardial contractility, meaning it enhances the strength and force of the heart's contractions. By increasing the contractility of the heart muscle, a positive inotropic agent leads to more effective pumping of blood throughout the body. This is particularly beneficial in conditions where the heart's ability to contract is impaired, such as heart failure, as it allows for improved cardiac output and better perfusion of vital organs. In contrast, decreasing the heart rate or myocardial contractility would not be the intended effect of a positive inotrope, as these outcomes would typically lead to a reduction in the heart's efficiency. Additionally, a decrease in cardiac output would also contradict the primary goal of administering a positive inotropic agent, which is designed to enhance the heart's pumping ability rather than diminish it. Thus, the correct understanding of a positive inotrope's effects directly correlates to its role in boosting myocardial contractility.