Pacemaker Panic

By Aarti Jain, MD
Algorithm for approach to the sick patient with a cardiac pacemaker

Case: An ill-appearing 88 yo M is brought in by EMS with a complaint of lightheadedness. You order IV, O2, cardiac monitor and glance up at the monitor to see:


How should you approach this type of patient?

Pacemaker basics:

  • Pulse generator palpable on anterior chest
  • Leads exit pulse generator and traverse subclavian vein to enter chambers of heart
  • Pacemaker code compromised of 5 letters
    • only first three letters are important for us- use pneumonic P-S-R…like “pacer”
  1. Chamber Paced (Atrium, Ventricle, or D-both)
  2. Chamber Sensed (Atrium, Ventricle, or D-both)
  3. Response to sensing (Triggered, Inhibited, D-both)

What should you ask on history?

Type of device?

Device company (St. Jude, Medtronic etc.)?

When placed?

When last interrogated?

Hopefully, the patient will have this card on them. ALWAYS ASK.

pacemaker 2


Screen Shot 2016-03-24 at 3.29.28 PM

What are you looking for with each of these tests?

CXR- Look for type of device and presence of complications

  • Type of device: Pacemaker or AICD?
    • Coils and lead #/orientation
      • Single chamber ICD
        • Coils PRESENT


  • Dual chamber pacemaker
    • Coils ABSENT, leads in RA, RV


  • Biventricular pacemaker with ICD
    • Coils ABSENT, leads in RA, RV, LV
    • Synchronizes contractions of RA/RV to improve ejection fraction
    • Presence of this device on CXR suggests HISTORY OF CHF


  • Complications seen on CXR
    • Pneumothorax
    • Lead fracture- often between first rib and clavicle
    • Lead migration
      • Change in EKG from LBBB to RBBB morphology suggests migration of RV lead into LV
    • Perforation-> pericardial effusion
    • Twiddler’s syndrome- patient rotates device (subconsciously) causing lead retraction

***Note: Pacemaker complications not identified on CXR include pouch hematoma/infection, upper extremity thrombosis, and cardiac device-related endocarditis.


EKG- Is the rate too slow? Is there a STEMI?

LBBB type pattern- spikes may or may not be visible. pacemaker6

Is the rate too slow? Look for:

  • Pacer spikes followed by no activity  


  • Long pauses


  • High degree AV block



Is there a STEMI?

  • Use Sgarbossa Criteria




Check bicarb, K+. Abnormalities can cause pacemaker dysfunction


All patients with a pacemaker and the symptoms mentioned above should undergo device interrogation (regardless of normal EKG/CXR). Many cases of device malfunction are only detected after interrogation.


When magnet is placed over pacemaker, device:

  • Stops sensing
  • Ignores intrinsic rhythm
  • Paces at fixed/regular rate


Consider using magnet in sick pacemaker patient whose EKG shows bradycardia. Understand that if pacemaker malfunction is extrinsic (i.e. lead fracture), magnet will not improve patient’s condition. Be prepared to give atropine/apply pacer pads if there is no improvement with application of magnet.

Note: If pacemaker patient presents in cardiac arrest, place pads in A/P orientation at least 8-10 cm from device. Also be prepared to externally pace patient after ROSC due to device failure secondary to chest compressions/severe acidosis.


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