What describes the outcome of Non-selective His Bundle Pacing?

The outcome of Non-selective His Bundle Pacing is best described by the presence of a pseudodelta wave with no isoelectric line between the paced and intrinsic QRS complexes. This phenomenon occurs because the pacing site is very close to both the His bundle and surrounding myocardial tissue, leading to simultaneous depolarization.

When pacing occurs at the His bundle level, the electrical impulse can spread rapidly through the bundle and also activate the surrounding myocardium almost concurrently. As a result, instead of a clean, clear separation that we would see in a typical paced complex, the QRS shows a wavefront that blends in with the pacing signal, creating the pseudodelta appearance. This lack of a distinct isoelectric line indicates that the transition between the pacing and the native conduction is not clear.

In this pacing scenario, the modifications in the QRS waveform can reflect the combined electrical activity of both the His bundle and the ventricular myocardium. This makes the observed change significant in assessing the quality and effectiveness of his bundle pacing as a therapeutic measure for various conduction disorders.