Paced electrical alternans with syncope: Time for emergent pericardiocentesis?

Area of Science:

• Cardiology
• Electrophysiology
• Medical Device Technology

Background:

• Left bundle branch area pacing (LBBAP) is a common strategy for cardiac device therapies.
• Established criteria exist for LBBAP capture, even in cases of left bundle branch block (LBB).

Purpose of the Study:

• To investigate the implications of LBBAP rate relative to the intrinsic refractory period of the left bundle branch (LBB).
• To highlight a specific case demonstrating the physiological consequences of pacing exceeding LBB refractoriness.

Main Methods:

• Case study analysis of a patient undergoing LBBAP.
• Observation of pacing capture patterns in relation to the LBB refractory period.

Main Results:

• A case of LBBAP at a rate exceeding the LBB refractory period was observed.
• This resulted in alternating LBBAP capture and non-selective septal pacing.

Conclusions:

• Understanding the LBB refractory period is crucial for LBBAP.
• This physiological insight is important for accurate lead placement assessment during LBBAP implantation.