The document discusses pacemakers, including their indications, types, and considerations for use. It provides details on: 1) Class I and II indications for pacemaker implantation including various types of acquired atrioventricular block and after myocardial infarction. 2) Types of pacemaker codes defining the chamber paced and sensed. 3) Special considerations for pacemaker patients in anesthesia, surgery, transport, and defibrillation to avoid electromagnetic interference.

1. Pacemakers For
House Officers
Frank W. Meissner, MD, FACP, FACC, FCCP
LtCol, USAF, MC, FS
Chief of Cardiology

2. Pacemakers For The Boards
●Pacemaker Codes
Position Category I II III
Chamber(s) Paced Sensed Response
Letter Code V=Ventricle V=Ventricle T=Triggered
A=Atrium A=Atrium I=Inhibited
D=Dual D=Dual D=Dual
S=Single O=None O=None
S=Single R=Reverse

3. ●Case Presentation
●22 y/o Caucasian male with pericarditis
+ CHB in November
●Athletic & avid outdoors man
●Backpacking trip in July Olympia Range
Pacemakers For The Boards

4. ●8-10% LD- pxts => cardiac injury
●Occurs median 5 weeks (range 3-21
weeks) post exposure
●Myopericarditis, pancarditis, & all
degrees (1°-3°) AV block
●Cardiac valves spared
●Due to direct invasion of spirochetes
●De novo or with other findings of LD
Pacemakers For The Boards

5. ●Hospitalize High-degree AV block or
P-R interval >0.3 seconds
●Marked risk for developing complete
heart block
●Temporary pacemaker insertion
necessary in some pxts
Pacemakers For The Boards

6. Pacemakers For The Wards
●Indications For Pacemaker Implantation
●Class I: Conditions for which there is general
agreement that permanent pacemakers or
antitachycardia devices should be implanted
●Class II: Conditions for which permanent
pacemakers or antitachycardia devices are frequently
used but there is divergence of opinion with respect
to the necessity of their insertion
●Class III: Conditions for which there is general
agreement that permanent pacemakers or
antitachycardia devices are unnessecary

7. Pacemakers For the Wards
●Class I - Acquired AV Block
●CHB, associated with:
○Symptomatic bradycardia
○CHF
○Pauses > 3.0 s or escape rate < 40 bpm
○Required drugs whose use causes
symptomatic bradycardia
○Confusional states that clear with pacing
○S/P AV nodal ablation, myotonic dystrophy

8. Pacemakers For the Wards
●Class I - Acquired AV Block
○2° AV block, with symptomatic bradycardia
○Atrial fibrillation/flutter or supraventricular
tachycardia + CHB or advanced AV block,
bradycardia, or condtions noted under CHB
indications

9. ●Class II- Acquired AV Block
●Asymptomatic complete heart block,
with ventricular rates of 40 beats/min or
faster
●Asymptomatic type II second degree AV
block
●Asymptomatic type I second degree AV
block at intra-His or infra-His levels
Pacemakers For the Wards

10. ●Class III- Acquired AV Block
●First degree AV block
●Asymptomatic type I second degree AV
block at the supra-His (AV node) level
Pacemakers For the Wards

11. ●Permanent Pacing After AMI
●Class I Indications
○Persistent advanced 2° AV block or CHB
with block in the His-Purkinje system
(bilateral bundle branch block)
Pacemakers For the Wards

12. Pacemakers For the Wards
●Permanent Pacing After AMI
●Class II Indications
○Persistent advanced block at the AV node
●Class III Indications
○Transient AV conduction disturbances
○Patients with persistent first degree AV
block in the presence of bundle branch
block not demonstrated previously

13. Pacemakers For the Wards
●Bifascicular & Trifascicular Block
●Class I Indications
○Bifascicular block + intermittent CHB block
+ symptomatic bradycardia
○Bifascicular or trifascicular block +
intermittent type II second degree AV block
●Class II Indications
○Bifascicular or trifascicular block + syncope
with noncardiac etiologies excluded
○HV interval >100 ms or Pacing-induced

14. Pacemakers For the Wards
●Bifascicular & Trifascicular Block
●Class III Indications
○Fascicular block without AV block or
symptoms
○Fascicular block with first degree AV block

15. Pacemakers For the Wards
●Anesthesia considerations
○EMI- Electromagnetic Interference
○Greater likelyhood unipolar than bipolar
○Myopotential interference � 15-20%
unipolar leads
○Electrocautery units may inhibit output
when used within several inches of pacer
○Magnet use in surgery may result in
random programming

16. Pacemakers For the Wards
●Electrocautery
○Grounding plate as far as possible from
pulse generator leads
○Pulse pressure or heart sounds should be
monitored ,
■EMI will render EKG useless for detection of
pacemaker inhibition
○Program unit asynchronous mode just prior
to procedure
○Shield pulse generator from radiation

17. Pacemakers For the Wards
●Patient transport
○Exercise caution in transfering patient since
dislodgement of leads is possible
○Rarely, positive pressure ventilation has
been reported to cause lead displacement
in rare cases

18. Pacemakers For The Units
●AV block in AMI
○Most common site of block
■AV node or prenodal atrial myocardium
■Usually in patients with inferior infarcts
■2ndary occlusion of RCA
○AV nodal block in this setting
■Prolonged PR interval =>
■Wenckebach type 2° AV block =>
■higher degrees of block, including complete AV
block
■Escape rhythm usually @ AV junction & is stable
with rate 50-60 bpm

19. Pacemakers For The Units
●AV nodal block usually transient &
asymptomatic
●Symptomatic block < 6hrs post-infarct
○Rx with Atropine effective
●Symptomatic block > 6hrs post-infarct
○Rx with Atropine ineffective
○Ischemic in origin

20. Pacemakers For The Units
●AV Nodal block +
○CHF, syncope, or ventricular arrhythmia
○=> temporary transcutaneous or
transvenous pacemaker
●High-grade AV nodal block MARKER for
large infarction
●Implies high risk complications & death
●Rx’ing AV block little prognostic benefit

21. Pacemakers For The Units
●Intra-Hisian or Infra-Hisian block far
more serious than AV nodal block
●Implies extensive AS/Anterior MI
●BBB + nml AV conduction =>
●Prolonged PR or Mobitz II block =>
●CHB
○CHB MAY appear precipitiously
○Slow & unstable idioventricular escape
rhythm

22. Pacemakers For The Units
●Mobitz type II block frequent
○RBBB &LAFB ± prolonged PR interval
○RBBB & LPFB even if nml PR interval
●Mortality independent of pacemaker
therapy
○Extensive infarcts cause His-Purkinje block
○Mechnical complications (CHF &
Cardiogenic Shock) cause of death

23. LAD
Circumflex
L-Main
RCA
AV NODE
HIS
BUNDLE
LPF
RBB
LAF
Conduction & Vascular System
3-D Spatial InterRelationships

24. Pacemakers For the Units
●Defibrillation
○Paddles not placed over pulse generator
○Use lowest output discharges
○Pacemaker function checked post-defib

25. Pacemakers For The ED
Posterior
To White EKG
To Black EKG
To Post Connector
To Anterior (Red
Band) Connector
Anterior
(over Septum @
V3 Position)

26. Pacemakers For The ED

27. Internal Jugular Vein Anatomy