During pacing, what could indicate capture of atria and ventricles?

The presence of visible signals of pacing that demonstrate coordination with the QRS complex is a clear indicator that both the atria and the ventricles are being captured during pacing. This coordination reflects that the pacing is effectively stimulating the heart tissues. When the pacing signals align with the QRS complexes on the ECG, it shows that the electrical impulses generated by the pacemaker are being transmitted through the conduction system, resulting in depolarization of the ventricles. This is crucial for maintaining effective and synchronized cardiac function.

Stable pacing output with no noise might suggest effective pacing, but it does not necessarily confirm that the heart is capturing both the atria and ventricles. Similarly, a high pacing threshold without loss of capture may indicate that pacing is successful at a certain energy level, but it does not provide direct evidence of QRS coordination, which is essential for confirming that both chambers are being stimulated appropriately. Atrial oversensing aligned with H signals might indicate that the pacemaker is picking up signals from the heart, but it does not confirm stimulation or effective capture of the ventricles.