Pacemaker complication
Nomenclature
- Position I
- Chamber paced (A, V, or D (dual))
- Position II
- Chamber sensed
- Position III
- Response after Sensing
- I = inhibited
- T = triggered
- D = Dual
- Response after Sensing
- Position IV
- Programmability
- P = rate & output
- M = multiprogramable
- C = communicating
- R = rate adaptive
- O = none
- Programmability
- Position V
- Arrhythmia Control
- P = pacing
- S = shock
- D = dual (P+S)
- O = none
- Arrhythmia Control
Indications
- Sinus Node Dysfunction-sinus bradycardia/arrest, sinoatrial block, chronotropic incompetence, a-fib.
- Acquired AV block- 3rd degree block and 2nd degree type II
- Chronic Bifascicular or Trifascicular block
- After Acute MI-high mortality with persistent AV block post MI
- Cardiac Resynchronization Therapy- Conduction delay (>150msec w/ mortality benefit) in chronic systolic heart failure further decreases EF, increases remodeling and increased MR.
- Neurocardiogenic Syncope and Carotid Sinus Syndrome
Expected ECG Patterns
- Absence of pacer artifact indicates intrinsic depolarization
- Pacing artifacts preceding depolarizations indicate successful pacing and capture
- Leads in RV apex produce LBBB pattern with appropriate discordance
- New RBBB pattern may indicate lead in LV
- Simulataneous depol of ventricles produces dominant R wave in V1
Methods to Identify Manufacturer
- Patient most often has a pocket card indicating manufacturer
- Magnet types are specific to each model so use magnets to deactivate pulse generator
- Manufactuer Hotline has patient database
- Medtronic Inc. (1-800-328-2518)
- St. Jude Medical Inc. (1-800-722-3774)
- Manufactuer code on pulse generator is visible on Chest Xray
Plain Film Findings
- Obtain PA/Lateral Films to confirm pulse generator, manufacturer, lead placement/number/integrity
- R atrial lead J shaped(tip medially on AP) entering right atrial appendage
- RV leads point downward with tip between left spine and cardiac apex--lateral XR shows inferior and anterior
- Coronary sinus lead- courses posteriorly on lateral XR
- Extra leads may be appropriately abandoned and capped
- ICD component appears as thickened shock coil
Pacemaker Malfunction
Problems with pocket
- Infection
- Most commonly Staphylococcus aureus or S. epidermidis
- Hematoma
- Typically occurs shortly after placement
Problems with leads
- Lead separation
- Lead dislodgment may cause thrombosis or myocardial rupture
- Lead infection can cause severe sepsis
- Leads can cause tricuspid regurg, dx w/ TTE
Failure to Capture
- Def-delivery of pacing stimulus without depolarization
- Functional- myocardium in refractory state or tissue reaction around lead insensitive
- Pathologic- drugs, myocardial disease, lytes
- Causes-lead dislodgement, fracture, perforation, insulation defect
Failure to Pace
- Def-failure to deliver a stimulus to the heart (w/ or w/o capture)
- Oversensing-most common cause-retrograde P’s, T’s, skeletal muscle myopotentials,
- Crosstalk- type of oversensing-vent lead senses atrial pacing stim, and vent output inhibited
Failure to Sense
- Signal sensed when myocardial depol sent up leads and into pacemaker, if voltage exceeds threshold, pacing inhibited(appropriately)
- Most commonly break in lead/insulation, battery
- Voltages of patient's intrinsic QRS complex is too low to be detected
- New intrinsic arrhythmia, AMI, electrolyte abnormalities, lead separation, battery depletion
Runaway Pacing
- Physiologic electrical activity (T waves, muscle potentials)
- External electromagnetic interference
- Signals generated by interaction of different portions of the pacing system
Work-Up
- CXR
- ECG
- Troponin
- Interrogation
Management
- Pacemaker Mediated Tachycardia- dual chamber devices-PAC or PVC trigger with pacemaker in loop. Break with adenosine or magnet.
- Use magnet to convert pacemaker to asynchronous mode if oversensing or runaway pacing
Electromagnetic Interference
- Nonmedical-
- Cell phones- do not interact w/ device
- Airport security-may trigger alarm, no alteration of activity
- Medical Sources
- MRI—mostly safe, consult cards on device specific recs
- Cardioversion- Use AP pads >8cm from device to minimize adverse effects
Sources
EB Medicine- Sept 2014- Managing Pacemaker-Related Complications and Malfunctions in the Emergency Department