What are the signs and symptoms that a pacemaker has stopped working?

Signs and Symptoms of Pacemaker Malfunction

When a pacemaker stops working, patients experience the return of their original bradycardia symptoms—most critically lightheadedness, presyncope, syncope, or confusional states—and in pacemaker-dependent patients, this can manifest as documented asystole or pauses ≥3 seconds, which is life-threatening. 1

Critical Warning Signs Requiring Immediate Evaluation

Syncope in any pacemaker patient must be presumed to be pacemaker-related until proven otherwise. 1 This is the most important clinical principle when evaluating these patients.

Life-Threatening Presentations

• Documented asystole or pauses ≥3 seconds, particularly in pacemaker-dependent patients (those with complete heart block, post-AV junction ablation, or no escape rhythm) 1
• Ventricular rate <40 bpm in symptomatic patients indicates complete device failure in patients with underlying complete heart block 1
• Sudden death can occur, though it is relatively rare as a direct consequence of pacemaker failure because most patients develop an idioventricular escape rhythm 2

Pacemaker-Dependent Patients at Highest Risk

Patients with the following conditions are at greatest risk from device failure and may experience immediate hemodynamic collapse 1:

• Complete heart block
• Post-AV junction ablation
• No underlying escape rhythm
• Myotonic dystrophy with AV block 3

Common Clinical Presentations

Bradycardia-Related Symptoms (Return of Original Indication)

The hallmark of pacemaker failure is recurrence of the symptoms that originally necessitated pacing 1:

• Lightheadedness and presyncope from inadequate cerebral perfusion 1
• Syncope (complete loss of consciousness), which in the presence of complete heart block must be presumed due to the block unless proven otherwise 3
• Confusional states that would clear with proper pacing function 3, 1
• Fatigue and exercise intolerance, particularly in patients who had chronotropic incompetence requiring rate-responsive pacing 1

Hemodynamic Compromise

• Congestive heart failure symptoms: worsening dyspnea, edema, or reduced cardiac output in pacemaker-dependent patients 1
• Hypotension: sudden drops in blood pressure >20 mmHg, especially in patients with ventricular-only pacing 1
• Malaise and weakness from inadequate cardiac output due to improper timing of atrial and ventricular contractions 1

Pacemaker Syndrome (Loss of AV Synchrony)

Even when the device is technically functioning, loss of proper AV synchrony can cause symptoms 3:

• Cannon A waves: visible neck pulsations from atrial contraction against closed AV valves 1
• New fatigue, dyspnea, or hypotension in VVI-paced patients 1
• Patient awareness of beat-to-beat variations with absence of AV synchrony 3

Specific Malfunction Patterns

Intermittent Symptoms

• Recurrent episodes of dizziness or near-syncope with specific movements (e.g., arm swinging) may indicate lead fracture or oversensing 4
• Symptoms on awakening or with positional changes 4

Battery Depletion

• Gradual onset of bradycardia symptoms as the pulse generator battery depletes 3
• This typically presents less acutely than lead failure 3

Critical Diagnostic Pitfalls to Avoid

The most dangerous error is assuming symptoms are non-cardiac in pacemaker patients with confusional states, bradycardia, or syncope—device malfunction should always be suspected first. 1

Common Mistakes

• Missing pacemaker syndrome: New fatigue, dyspnea, or hypotension in VVI-paced patients may represent loss of AV synchrony rather than complete device failure 1
• Attributing syncope to other causes without first ruling out device malfunction 3, 1
• Failing to recognize that most syncope in pacemaker patients is unrelated to the device 3, but this can only be determined after thorough device interrogation

Immediate Assessment Priorities

When pacemaker malfunction is suspected 1:

• Document vital signs including blood pressure and orthostatic changes to assess hemodynamic compromise 1
• Obtain 12-lead ECG to identify pacing spikes, capture, and underlying rhythm 5
• Assume device failure in pacemaker-dependent patients presenting with bradycardia or syncope until proven otherwise 1
• Arrange urgent device interrogation to confirm malfunction type (sensing failure, capture failure, lead fracture, battery depletion) 5, 4

Specific ECG Findings

Look for 5:

• Absence of pacing spikes when expected
• Pacing spikes without myocardial capture
• Inappropriate sensing (oversensing or undersensing)
• Intermittently non-conducted P waves corresponding to inappropriate pacemaker inhibition 4