Advanced Patient Assessment Practice Exam

Which of the following dysrhythmias is associated with the lowest cardiac output?

1. AV block

2. Atrial fibrillation

3. Ventricular flutter

4. Ventricular fibrillation

The correct answer is: Ventricular fibrillation

Ventricular fibrillation is associated with the lowest cardiac output due to its chaotic electrical activity that prevents the heart muscle from contracting effectively. In this condition, the ventricles quiver instead of contracting in a synchronized manner, resulting in a complete loss of effective blood pumping action. As a consequence, there is virtually no perfusion of blood to the body's vital organs, leading to a critical drop in cardiac output. In contrast, atrial fibrillation may decrease cardiac output but still allows for some level of blood flow due to the presence of residual mechanical function of the heart. AV block can lead to impaired heart rate and may cause reduced cardiac output, but it does not achieve the total loss experienced in ventricular fibrillation. Lastly, ventricular flutter, while very rapid and potentially lethal, still maintains some degree of coordinated contraction compared to the disorganized activity seen in ventricular fibrillation, resulting in a somewhat better cardiac output. Understanding these distinctions helps to clarify the severity of each dysrhythmia and their potential impact on cardiac function.