What is the best course of action for a patient experiencing palpitations and pounding in the chest after their pacemaker (artificial cardiac pacemaker) was activated 6 months ago?

Immediate Pacemaker Interrogation and Evaluation Required

This patient requires urgent pacemaker interrogation to assess device function, review stored events from 6 months ago, and evaluate for pacemaker-mediated tachycardia or other device-related arrhythmias causing their persistent symptoms. 1

Initial Assessment and Device Interrogation

The 6-month duration of symptoms following pacemaker activation strongly suggests a device-related issue rather than a transient problem. Immediate steps include:

• Interrogate the pacemaker to review stored electrograms and event logs from the time symptoms began, checking for inappropriate mode switching, pacemaker-mediated tachycardia, or sensing abnormalities 1
• Assess current programming parameters including pacing mode, rate response settings, and upper rate limits that may be triggering palpitations 1
• Evaluate for functional undersensing or oversensing that can cause inappropriate pacing and palpitations, particularly if rate-adaptive algorithms are active 2, 3
• Obtain 12-lead ECG during symptoms to correlate palpitations with pacing activity and identify pacemaker-mediated arrhythmias 1

Common Device-Related Causes of Persistent Palpitations

Several pacemaker programming issues can cause chronic palpitations:

• Pacemaker-mediated tachycardia (PMT) occurs in dual-chamber devices when retrograde atrial activation triggers ventricular pacing, creating a reentrant circuit 4
• Inappropriate rate response from accelerometer or minute ventilation sensors can cause rapid pacing with minimal activity 1
• Upper rate behavior where the device reaches programmed upper rate limits during normal activity, causing sudden rate changes 1
• AV synchrony loss or suboptimal AV delay programming can cause "pacemaker syndrome" with palpitations and chest discomfort even without hemodynamic compromise 1

Specific Diagnostic Steps

Beyond basic interrogation, targeted evaluation should include:

• 24-hour Holter monitoring with pacemaker marker channels to capture symptomatic episodes and correlate with device behavior 1
• Exercise testing with continuous ECG monitoring to assess rate response appropriateness and upper rate behavior during activity 1
• Transtelephonic monitoring if symptoms are intermittent and difficult to capture, allowing real-time rhythm transmission during palpitations 1

Reprogramming Strategies

Once device interrogation identifies the mechanism:

• Disable or adjust rate-adaptive pacing if sensor-driven rate increases correlate with symptoms 1
• Extend post-ventricular atrial refractory period (PVARP) to prevent PMT in dual-chamber devices 1
• Optimize AV delay to restore physiologic AV synchrony and reduce atrial stretch that can trigger palpitations 1
• Lower upper rate limits if tracking or sensor-driven rates are excessive for the patient's activity level 1

Critical Pitfalls to Avoid

• Do not assume symptoms are unrelated to the device simply because the pacemaker is "functioning normally" on basic interrogation—stored event logs and detailed programming review are essential 1
• Functional undersensing can mimic device malfunction when actually caused by algorithm-specific refractory periods, particularly with managed ventricular pacing (MVP) or similar modes 2
• Remote monitoring alone cannot replace in-person evaluation for persistent symptoms requiring detailed interrogation and potential reprogramming 1

When to Consider Lead or Hardware Issues

If reprogramming fails to resolve symptoms, evaluate for:

• Lead dislodgement or microdislodgement causing intermittent capture failure and compensatory pacing, though this typically presents earlier than 6 months post-implant 1
• Elevated pacing thresholds requiring higher output that patients may perceive as pounding 1
• Lead insulation breach or conductor fracture causing erratic sensing and inappropriate pacing responses 5

Follow-Up Protocol

After intervention:

• Repeat device interrogation at 2-4 weeks to confirm symptom resolution and assess any new stored events 1
• Continue monitoring at 6-month intervals once stable, with more frequent checks if battery depletion is approaching or symptoms recur 1
• Patient should maintain device identification card and report any symptom recurrence immediately rather than waiting for scheduled follow-up 1

The persistence of symptoms for 6 months indicates this is not a self-limited issue and requires active intervention through systematic device evaluation and reprogramming.