1. Supparerk Prichayudh M.D
Pacemaker
Supparerk Prichayudh M.D

3. Normal EKG P wave = atrial depolarization
QRS wave = ventricular depolarization
T wave = ventricular repolarization

4. Outline Indications Types Modes of pacemaker Temporary pacemaker
Problems with pacemakers
Surgical diathermy and pacemakers

5. Indications

6. Indication: Symptomatic bradycardia
Sinus node dysfunction
3° and advanced 2° AV block
Bradycardia associated with AMI

7. Prophylactic Implant
Patients with LBBB requiring Swan-Ganz catheter placement
Cardioversion in the setting of SSS
New BBB in the setting of acute endocarditis
Peri-operatively

8. Sick Sinus Syndrome

13. Types
Temporary
Permanent

14. Permanent pacemaker Box = pulse generator

15. Pacemaker Leads
Pacemaker leads are the conduits from the generator to the myocardium. Most leads are implanted transvenously.

16. Wiring systems Unipolar Bipolar One electrode on the heart (-)
Signals return through body fluid and tissue to the pacemaker (+)
Bipolar
Two electrodes on the heart (- & +)
Signals return to the ring electrode (+) above the lead (-) tip

17. UNIPOLAR AND BIPOLAR PACING

19. Modes of pacemaker

20. NASPE-BPEG Generic Five-Position Code
Position I II
III IV V
Parameter measured
Chamber(s) paced
Chamber(s) sensed
Response to sensing
Rate modulation
Anti-tachyarrhythmia function
Possible values
O = None
A = Atrium
I = Inhibited
R = Rate modulation on
P = Pace
V = Ventricle
T = Triggered
S = Shock
D = Dual (A + V)
D = Dual (I + T)
D = Dual
NASPE, North American Society of Pacing and Electrophysiology; BPEG, British Pacing and Electrophysiology Group

21. First letter: Chamber Paced
V- Ventricle
A- Atrium
D- Dual (A & V)
O- None

22. Second letter: Chamber Sensed
V- Ventricle
A- Atrium
D- Dual (A & V)
O- None

23. Third letter: Sensed Response
T- Triggers Pacing
I- Inhibits Pacing (demand)
D- Dual (synchronous)
O- None (asynchronous)

24. Chamber Paced Atrial pacing Ventricular pacing
Intact AV conduction system required
Ventricular pacing
Loss of atrial kick
Atrial/Ventricular pacing
Natural pacing
Atrial-ventricular synchrony

25. Commonly used modes AAI - atrial demand pacing
VVI - ventricular demand pacing
DDD – Dual chamber pacemaker
AOO - atrial asynchronous pacing
VOO - ventricular asynchronous pacing

26. ventricular asynchronous pacing VOO
Indications
Temporary mode some-times used during surgery to prevent interference from electrocautery

27. ventricular demand pacing VVI
Indications
The combination of AV block and chronic atrial arrhythmias (particularly atrial fibrillation).

28. atrial demand pacing AAI
Indications
Sick sinus syndrome in the absence of AV node disease or atrial fibrillation.

29. atrial synchronous ventricular inhibited pacemaker VDD
Indications
AV block with intact sinus node function (particularly useful in congenital AV block).

30. Dual chamber pacemaker DDD
Indications
1. The combination of AV block and SSS.
2. Patients with LV dysfunction and LV hypertrophy who need coordination of atrial and ventricular contractions to maintain adequate CO.

31. Temporary pacemaker

32. Types
Transvenous- pacing wire via central line to RV under X ray, usually bipolar i.e., with 2 electrodes at the end of wire
Transthoracic (epicardial lead)  post op pacer wires.
Transcutaneous  one electrode over cardiac apex, other over right scapula or clavicle.
Transesophageal

33. Transcutaneous pacemaker
Posterior  Lt side of the spine, behind the scapula, directly behind the anterior electrode. Avoid placement over bone.
Anterior  Upper = below nipple, center =V2, V3 position, Female= under the breast, above diaphragm.
Output  Increase gradually until captures, then increase 10% more.
Require sedation and analgesia.

34. Transvenous pacemaker

40. Medtronic 5388 Dual Chamber

44. Setting Atrial and ventricular output (lowest possible)
Milliamperes (mA)
Typical atrial mA 5
Typical ventricular mA 8-10
Atrial/ventricular rate
Set at physiologic rate for individual patient
Post open heart sugery  90/min
AV Interval, upper rate, & PVARP automatically adjust with set rate changes
Atrial and ventricular sensitivity
Millivolts (mV)
Typical atrial: 0.4 mV
Typical ventricular: 2.0mV

45. Setting (cont.) AV Interval Milliseconds (msec) Upper rate
Time from atrial sense/pace to ventricular pace
Synonymous with “PR” interval
Upper rate
Automatically adjusts to 30 bpm higher than set rate
Prevents pacemaker mediated tachycardia from unusually high atrial rates
Wenckebach-type rhythm results when atrial rates are sensed faster than the set rate
Refractory period
PVARP: Post Ventricular Atrial Refractory Period
Time after ventricular sensing/pacing when atrial events are ignored

48. Normal Pacing
Atrial Pacing
Atrial pacing spikes followed by P waves

49. Normal Pacing Ventricular pacing
Ventricular pacing spikes followed by wide, bizarre QRS complexes

50. Normal Pacing A-V Pacing
Atrial & Ventricular pacing spikes followed by atrial & ventricular complexes

51. Normal Pacing
DDD mode of pacing
Ventricle paced at atrial rate

52. Assessing Underlying Rhythm

53. Problems with pacemakers

54. Problems with pacemakers
Failure to pace
Failure to capture
Failure to sense (overpacing)
Wenkebach
Pacemaker syndrome

55. 1. Failure to Pace Causes: Oversensing Battery failure
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
Causes:
Oversensing
Battery failure
Internal insulation failure
Conductor coil fracture

56. Problems with Pacemakers Failure to Pace
Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005.
Causes:
Crosstalk (V oversensing when A paced)

57. Oversensing
Pacing does not occur when intrinsic rhythm is inadequate

58. Oversensing Causes Danger - heart block, asystole
Pacemaker inhibited due to sensing of “P” waves & “QRS” complexes that do not exist
Pacemaker too sensitive
Possible wire fracture, loose contact
Pacemaker failure
Danger - heart block, asystole

59. Oversensing Solution View rhythm in different leads Change electrodes
Check connections
Decrease pacemaker sensitivity (↑mV)
Change cables, battery, pacemaker
Reverse polarity
Check electrolytes
Unipolar pacing with subcutaneous “ground wire”

60. Reversing polarity Changing polarity Requires bipolar wiring system
Reverses current flow
Switch wires at pacing wire/bridging cable interface

61. 2. Failure to Capture Atrial non-capture
Atrial pacing spikes are not followed by P waves

62. Failure to Capture Ventricular non-capture
Ventricular pacing spikes are not followed by QRS complexes

63. Failure to Capture Causes Danger - poor cardiac output
Insufficient energy delivered by pacer
Low pacemaker battery
Dislodged, loose, fibrotic, or fractured electrode
Electrolyte abnormalities
Acidosis
Hypoxemia
Hypokalemia
Danger - poor cardiac output

64. Failure to Capture Solutions View rhythm in different leads
Change electrodes
Check connections
Increase pacer output (↑mA)
Change battery, cables, pacer
Reverse polarity

65. 3. Failure to Sense (overpacing)
Atrial undersensing
Atrial pacing spikes occur regardless of P waves
Pacemaker is not “seeing” intrinsic activity

66. Failure to Sense Ventricular undersensing
Ventricular pacing spikes occur regardless of QRS complexes
Pacemaker is not “seeing” intrinsic activity

67. Competition Pacemaker & patient’s intrinsic rate are similar
Unrelated pacer spikes to P wave, QRS complex
Fusion beats

68. Failure to Sense Causes
Pacemaker not sensitive enough to patient’s intrinsic electrical activity (mV)
Insufficient myocardial voltage
Dislodged, loose, fibrotic, or fractured electrode
Electrolyte abnormalities
Low battery
Malfunction of pacemaker or bridging cable

69. Failure to Sense
Danger – potential (low) for paced ventricular beat to land on T wave (R on T)  VF!!

70. Failure to Sense Solution View rhythm in different leads
Change electrodes
Check connections
Increase pacemaker’s sensitivity (↓mV)
Change cables, battery, pacemaker
Reverse polarity
Check electrolytes
Unipolar pacing with subcutaneous “ground wire”

71. 4. Wenckebach Assessment Appears similar to 2nd degree heart block
Occurs with intrinsic tachycardia

72. Wenckebach Causes DDD mode safety feature
Prevents rapid ventricular pacing impulse in response to rapid atrial rate
Sinus tachycardia
Atrial fibrillation, flutter
Prevents pacer-mediated tachycardia
Upper rate limit may be inappropriate

73. Wenckebach Solution Treat cause of tachycardia
Fever: Cooling
Atrial tachycardia: Anti-arrhythmic
Pain: Analgesic
Hypovolemia: Fluid bolus
Adjust pacemaker upper rate limit as appropriate

74. 5. Pacemaker syndrome
Ventricular pacing  sacrifice the atrial contribution to ventricular output
Loss of AV synchrony  Atrium contracts against closed TV,MV  ↓ CO, ↑ JVD
Retrograde ventriculoatrial (VA) conduction  inverted P, ↑ PR, AV dissociation
Absence of rate response to physiologic need
14-57% in VVI
Patients with intact VA conduction are at greater risk

75. Rx VVI  Add A-lead, ↓ Rate
Other  interrogation and reprogramming to fix loss of AV synchrony

76. Surgical diathermy and pacemakers

77. Ventricular fibrillation – most common if pacemaker unit is older type
Inhibition of demand function- sensing may be triggered, with resultant chamber inhibition or arrhythmias induced
Unpredictable setting of programmable types
Asystole
Unit failure

78. Recommendations
Place indifferent electrode on same side as operation & as far from pacemaker unit as possible
Limit use of diathermy
Use lowest current setting possible
Use bipolar diathermy
Careful monitoring of pulse, pulse oximetry & arterial pressure
Transcutaneous pacing should be available
Isoprenaline should be available
Interrogation before Sx
Magnet
Reset PM to asynchronous
Inactivate defribillation feature in AICD

79. Post operative care Full telemetric check
Reprogramming back to original setting

80. THANK YOU