Cardiac Medicine Certification (CMC) Practice Exam

What EKG changes are typically seen in heart failure?

1. Elevated T waves and shorter QT interval

2. Prolonged QRS and junctional rhythm

3. Inverted P waves and ST depression

4. Normal sinus rhythm with occasional PVCs

The correct answer is: Prolonged QRS and junctional rhythm

In the context of heart failure, the presence of a prolonged QRS complex along with junctional rhythms reflects intrinsic conduction abnormalities that can occur due to structural and electrical remodeling in the heart. Heart failure can lead to changes in the heart's electrical conduction system, which often includes widening of the QRS complex. This prolongation suggests a slower conduction through the ventricles, typically seen in situations where the ventricular walls become dilated or when there is a block in the conduction system. Junctional rhythms may arise as a compensatory mechanism when the atrial activity is impaired or when the atrioventricular (AV) node takes over pacemaking in the absence of effective atrial contractions. This can occur in advanced heart failure where it is common to have decreased atrial effectiveness or significant arrhythmias. Recognizing these changes on an EKG is essential for diagnosing and managing heart failure effectively, as it helps to identify the severity of the condition and guides treatment decisions. While other choices mention different EKG findings, only the combination of a prolonged QRS and a junctional rhythm clearly aligns with the expected EKG alterations associated with heart failure.