What causes the wandering pacemaker rhythm?

What causes the wandering pacemaker rhythm?

• A. SA node damage
• B. Pacemaker activity wandering from the SA node to nearby atrial automaticity foci
• C. Increased vagal tone
• D. Myocardial ischemia

Answer: (B)

The wandering pacemaker rhythm is characterized by a variation in the pacemaker sites within the atria, which can result in different P-wave morphologies on the ECG. This phenomenon is primarily caused by pacemaker activity migrating from the dominant Sinoatrial (SA) node to nearby atrial automaticity foci, which can intermittently assume control over the heart rate.

As these foci take over, they may generate impulses that originate from various locations within the atrial tissue, leading to changes in P-wave shapes and intervals. This can also create variability in heart rate and atrial activity, as different foci may discharge at different rates.

Understanding this mechanism is crucial for interpreting the EKG correctly, as it highlights the normal adaptive responses of the heart to changing physiologic conditions, often seen in younger and healthier individuals.