Progressive Care Nursing Certification (PCCN) Practice Exam

A patient with QT prolongation is at risk for which condition?

1. Atrial fibrillation

2. 2nd degree heart block type II

3. Ventricular dysrhythmia

4. Paroxysmal atrial tachycardia

The correct answer is: Ventricular dysrhythmia

QT prolongation is a condition in which the time it takes for the heart's electrical system to recharge after each heartbeat is lengthened. This prolongation can lead to a higher risk of life-threatening ventricular dysrhythmias, specifically Torsades de Pointes, which is a specific type of polymorphic ventricular tachycardia. The reason ventricular dysrhythmias are a concern in patients with QT prolongation is tied to the structure of the cardiac action potential. When the QT interval is prolonged, it can lead to early afterdepolarizations, which can trigger abnormal heart rhythms. This is particularly critical because these dysrhythmias can result in insufficient blood flow to vital organs and may lead to decreased cardiac output, syncope, or even sudden cardiac arrest. While other options may refer to potential heart rhythm issues, they are less directly related to the risks associated with QT prolongation. For instance, atrial fibrillation relates to the upper chambers of the heart, whereas second-degree heart block type II and paroxysmal atrial tachycardia involve different mechanisms that are not primarily influenced by QT interval prolongation. Thus, ventricular dysrhythmias are the most immediate and serious concern in this scenario.