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

What is a characteristic sign of decreased myocardial contractility?

1. Increased heart rate

2. Improved cardiac output

3. Poor perfusion and low blood pressure

4. High urine output

The correct answer is: Poor perfusion and low blood pressure

Decreased myocardial contractility negatively impacts the heart's ability to pump blood effectively. As a result, the heart struggles to generate sufficient force during contraction, which can lead to a decrease in cardiac output. This suboptimal blood circulation often manifests as poor tissue perfusion since the organs and muscles are not receiving enough blood to function properly. Consequently, one may observe signs such as low blood pressure due to impaired output, as well as other indications of reduced perfusion, including cool extremities and altered mental status. In contrast, increased heart rate, while sometimes present as a compensatory response to low cardiac output, does not directly relate to the contractility itself and can often be misleading. Improved cardiac output would indicate enhanced myocardial contractility, which is contrary to the premise of the question. High urine output typically signals effective kidney perfusion and can be a sign of good cardiac function, again not aligning with decreased myocardial contractility.