Certified EkG technician (CET) Practice Exam

In cases of third-degree AV block, what should the technician monitor for?

1. Increased heart rate

2. Signs of decreased cardiac output

3. Long QT intervals

4. ST segment elevation

The correct answer is: Signs of decreased cardiac output

In cases of third-degree AV block, monitoring for signs of decreased cardiac output is critical. Third-degree AV block, also known as complete heart block, is characterized by a complete failure of the electrical signals from the atria to conduct to the ventricles. This often leads to a significant disruption of the heart's normal rhythm and can result in a slow ventricular rate, which diminishes the amount of blood pumped to the body. As the ventricles fail to properly receive signals from the atria, they often rely on a slower intrinsic pacemaker. This slow heart rate (often in the 20-40 beats per minute range) can lead to inadequate tissue perfusion, causing symptoms such as fatigue, dizziness, and in severe cases, syncope or heart failure. Therefore, monitoring for signs of decreased cardiac output—such as hypotension, confusion, or the presence of cool extremities—becomes essential for patient safety and management. Other options listed pertain to different aspects of cardiac monitoring but are not the primary concern in third-degree AV block. Increased heart rate is typically not seen in this condition; long QT intervals may indicate other arrhythmias; and ST segment elevation is generally associated with myocardial ischemia rather than with AV block. Thus,