Atrial lead malposition in a dual chamber (DDD,M) pacemaker

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Device Technology

Background:

• Pacemakers are vital for managing cardiac arrhythmias.
• Dual-chamber pacing modes require precise lead placement for optimal function.
• Lead dislodgement can lead to pacing complications and suboptimal therapy.

Observation:

• A Model 7000 pacemaker, programmed in DVI mode, delivered two stimuli.
• The atrial lead was identified within the right ventricular outflow tract.
• The QRS complex generated by the misplaced atrial lead occurred after the pacemaker's blanking period.

Findings:

• The atrial lead's signal "committed" the subsequent ventricular stimulus.
• This resulted in the ventricular stimulus being delivered 110 ms after the "atrial" stimulus, despite the atrial lead's inappropriate position.
• The pacemaker's behavior was a consequence of the lead's location, not a device malfunction.

Implications:

• Intracardiac electrography during pacemaker implantation is critical for verifying correct lead placement.
• Failure to confirm proper lead positioning can result in pacing abnormalities and potential patient harm.
• This case highlights the importance of procedural checks in cardiac device implantation to prevent complications.