In what situation is the pacemaking from atrial automaticity foci observed in MAT?

In what situation is the pacemaking from atrial automaticity foci observed in MAT?

• A. One pacemaker dominates the others
• B. All foci pace together without achieving dominance
• C. SA node continuously suppresses all foci
• D. Foci switch dominance periodically

Answer: (B)

In multifocal atrial tachycardia (MAT), multiple atrial automaticity foci can generate impulses at the same time. The scenario where all foci pace together without achieving dominance is a hallmark characteristic of MAT. This leads to a chaotic and irregular rhythm, as the impulses from these different foci compete to take control of the heart rhythm without any single focus being able to suppress the others.

In this situation, the result is a varied and irregular atrial activation pattern due to the concurrent firing of multiple ectopic foci, which can lead to the characteristic multi-shaped P waves observable on an electrocardiogram (ECG). This observation underscores the nature of MAT, where no single pacemaker is consistently dominant, allowing for the maintenance of an irregularly rapid heart rhythm.