What are the symptoms and management of pseudo pacemaker syndrome?

Symptoms Associated with Pseudo Pacemaker Syndrome

Pseudo pacemaker syndrome presents with symptoms of hemodynamic instability due to AV dyssynchrony caused by a markedly prolonged PR interval, similar to those seen in pacemaker syndrome but without an implanted pacemaker. 1

Clinical Presentation

Primary Symptoms

• Palpitations (most common presenting symptom) 1
• Syncope or near-syncope 2, 3
• Dizziness or light-headedness 2
• Fatigue 2, 4
• Malaise secondary to low cardiac output 2
• Confusion due to cerebral hypoperfusion 2

Hemodynamic Manifestations

• Decreased cardiac output 4
• Hypotension 2, 4
• Elevated ventricular filling pressures 2
• Venous "cannon A waves" due to atrial contraction against closed AV valves 4

Pathophysiological Mechanism

The fundamental mechanism involves:

• Markedly prolonged PR interval (typically >300 ms, can be as high as 480 ms) 3
• P wave occurring too close to the preceding QRS complex 3
• AV dyssynchrony causing improper timing of atrial and ventricular systole 2
• Atrial contraction occurring during ventricular systole or early diastole 4
• Sudden increase in atrial pressure triggering systemic hypotensive reflex 4

Etiologies of Pseudo Pacemaker Syndrome

Four main causes have been identified:

1. Idiopathic PPMS with impaired AV nodal conduction (20% of cases) 1
2. Reversible inflammatory causes (13% of cases) 1
3. Iatrogenic damage to AV conduction system following surgical or interventional procedures (20% of cases) 1
4. Dual AV nodal physiology - either as primary finding (27%) or after ablation procedures for AVNRT (20%) 1, 5

Other specific scenarios:

• Acute inferior myocardial infarction with conduction disturbances 3
• Sinus node disease with junctional rhythm and retrograde VA conduction 6
• Selective fast pathway ablation for AVNRT 5

Diagnostic Approach

• ECG showing markedly prolonged PR interval (typically >300 ms) 3
• Correlation between symptoms and the presence of first-degree AV block 5
• Often associated with sinus tachycardia 5
• Exclusion of other causes of syncope or hemodynamic compromise 5
• Hemodynamic assessment showing decreased cardiac output during episodes 4

Management Options

Treatment should be tailored to the specific etiology:

1. For persistent symptomatic cases:

   • Permanent pacemaker implantation 1, 5
   • Complete AV block induction with catheter ablation followed by permanent pacing 5

2. For reversible causes:

   • Temporary pacing until conduction system recovers 3
   • Treatment of underlying inflammatory condition 1

3. Preventive measures:

   • During ablation procedures for AVNRT, preserve fast nodal pathway when possible 5
   • Monitor PR interval in patients with inferior MI or after cardiac interventions 3

Clinical Pearls and Pitfalls

• First-degree AV block is usually asymptomatic and does not require treatment unless associated with pseudo pacemaker syndrome 3
• The syndrome can occur spontaneously and should be considered during investigation of unexplained syncope 5
• Middle-aged and young adults (average age 47) are most commonly affected 1
• Symptoms may be identical to those seen in true pacemaker syndrome with VVI pacing 6
• Pseudo pacemaker syndrome should be suspected in any patient with marked first-degree AV block and unexplained symptoms of hemodynamic compromise 1, 3