1. Dr.Gharibzadeh Alaleh Rashidnasab
Pacemakers and ICD’s
Dr.Gharibzadeh
Alaleh Rashidnasab

2. SCD most common cause of death

3. Sudden Cardiac Death

4. Sudden Cardiac Death Death by an arrhythmia: Bradycardia Tachycardia
Atrial Fibrillation
Ventricular Fibrillation

5. Bradycardia Sinus node discharges at a rate < 60 bpm
Decreased CO may occur

6. Tachycardia
Discharge rate from the sinus node is increased and is > 100 bpm
Increased myocardial oxygen consumption is associated with increased HR

7. Atrial Fibrillation
Total disorganization of atrial activity without effective atrial contraction
Can often result in decrease in CO because of ineffective atrial contractions and rapid ventricular response
Goals are decreased in ventricular response and conversion to sinus rhythm

8. Ventricular Fibrillation
Severe derangement of the heart rhythm characterized on ECG by irregular undulations of varying contour and amplitude
No effective contraction or CO occurs
If untreated, patient will die

9. Treatments Drug therapy Defibrillators Pacemakers
ICDs(Implantable Cardioverter Defibrillator):
ICD Therapy consists of pacing, cardioversion, and defibrillation therapies to treat brady and tachy arrhythmias

10. Historical Perspective
1905 – Einthoven
Published first two human AV block using string galvanometer
1958 – Senning and Elmqvist
Asynchronous (VVI) pacemaker implanted by thoracostomy and functioned for 3 hours
Arne Larsson
First pacemaker patient
Used 23 pulse generators and 5 electrode systems
Died 2001 at age 86 of cancer

11. Historical Perspective
1960 – First atrial triggered pacemaker
1964 – First on demand pacemaker (DVI)
1977 – First atrial and ventricular demand pacing (DDD)
1980 – Griffin published first successful pacemaker intervention for supraventricular tachycardias

12. Historical Perspective
1981 – Rate responsive pacing by QT interval, respiration, and movement
1994 – Cardiac resynchronization pacing
1998 – Automatic capture detection
Now
Approximately 3 million with pacemakers
Approximately 1 million with ICD device

13. 1980 Large devices - Abdominal site
First human implants
Thoracotomy, multiple incisions
Primary implanter= cardiac surgeon
General anesthesia
Long hospital stays
Complications from major surgery
Perioperative mortality up to 9%
Nonprogrammable therapy
High-energy shock only
Device longevity  1.5 years
Fewer than 1,000 implants/year

14. Today Small devices - Pectoral site
First-line therapy for VT/VF patients
Treatment of atrial arrhythmias
Cardiac resynchronization therapy for HF
Transvenous, single incision
Local anesthesia; conscious sedation
Short hospital stays and few complications
Perioperative mortality < 1%
Programmable therapy options
Single- or dual-chamber therapy
Battery longevity up to 9 years
More than 100,000 implants/year

15. Evolution of ICD Therapy:

16. Pacemaker Basics
Provides electrical stimuli to cause cardiac contraction when intrinsic cardiac activity is inappropriately slow or absent
Sense intrinsic cardiac electric potentials

17. A Brief History of Pacemakers

18. ICD Basics Designed to treat a cardiac tachydysrythmia
An external programmer is used to monitor and access the device parameters and therapies for each patient.
Performs cardioversion/defibrillation
Ventricular rate exceeds programmed cut-off rate
ATP (antitachycardia pacing)
Overdrive pacing in an attempt to terminate ventricular tachycardias
Some have pacemaker function (combo devices)

20. Implantable Defibrillators (1989-2003)
120 cc
209 cc
80 cc
80 cc
72 cc
54 cc
62 cc
49 cc
39.5 cc
39.5 cc
36 cc
39.5 cc
38 cc

21. Pacemaker and ICD Basics
Pulse Generators
Placed submuscularly
Connected to leads
Battery
Most commonly lithium-iodide type
Life span 5 to 8 years
Output voltage decreases gradually
Makes sudden battery failure unlikely

22. Pacemaker and ICD Basics
Asynchronous
Fixed rate
Impulse produced at a set rate
No relation to patients intrinsic cardiac activity

23. Pacemaker and ICD Basics
Synchronous
Demand mode
Sensing circuit searches for intrinsic depolarization potential
If absent, a pacing response is generated
Can mimic intrinsic electrical activity pattern of the heart

24. Pacemaker Lead System Endocardial leads placed via central access
Placed in right ventricle and/or atria
Fixed to the endocardium via screws or tines
Experimental pacing systems
2 atrial leads (minimize afib)
Biventricular pacing

27. Pacemaker Indications
Absolute indications
Sick sinus syndrome
Symptomatic sinus bradycardia
Tachy-brady syndrome
Afib with slow ventricular response
3rd degree heart block
Chronotropic incompetence
Inability to increase heart rate to match exercise

28. ICD Indications Generally
Used in cases where there was a previous cardiac arrest
Or, patients with undetermined origin or continued VT or VF despite medical interventions

29. Pacemaker Complications
EKG abnormalities due to
Failure to output
Failure to capture
Sensing abnormalities

30. Pacemaker Failure to Output
Definition
No pacing spike present despite indication to pace
Etiology
Battery failure, lead fracture, break in lead insulation, oversensing, poor lead connection, “cross-talk”
Atrial output is sensed by ventricular lead

31. Pacemaker Failure to Capture
Definition
Pacing spike is not followed by either an atrial or ventricular complex
Etiology
Lead fracture or dislodgement, break in lead insulation, elevated pacing threshold, MI at lead tip, drugs, metabolic abnormalities, cardiac perforation, poor lead connection

32. Pacemaker Sensing Abnormalities
Oversensing
Senses noncardiac electrical activity and is inhibited from correctly pacing
Etiology
Muscular activity (diaphragm or pecs), EMI, cell phone held within 10cm of pulse generator
Undersensing
Incorrectly misses intrinsic depolarization and paces
Poor lead positioning, lead dislodgement, magnet application, low battery states, MI

33. ICD Complications Similar to pacemaker complications
Sensing and pacing failures
Inappropriate cardioversion
Ineffective cardioversion/defibrillation

34. ICD Sensing failures
Similar to pacmakers
Oversensing
Undersensing

35. ICD Inappropriate Cardioversion
Most frequent complications
Provokes pain and anxiety in pts
Consider when
Pt is in afib
Received multiple shocks in rapid succession
Etiology
Afib, T-wave oversensing, lead fracture, insulation breakage, MRI, EMI

36. ICD Inappropriate Cardioversion
Treatment
Magnet over ICD inhibits further shocks
Does NOT inhibit bradycardiac pacing
Note
Some older devices produce beep with each QRS
If left on for >30 seconds, ICD disabled and continous beep
To reactivate, lift off magnet and then replace for > 30 seconds, beep will return with each QRS

37. ICD Failure to Deliver Cardioversion
Etiology
Failure to sense, lead fracture, EMI, inadvertent ICD deactivation
Management
External defibrillation and cardioversion
Do not withhold therapy for fear of damaging ICD
If pt’s internal defibrillator activates during chest compressions, you may feel a mild shock (no reports of deaths related to this)
Antidysrhymthic medications

38. ICD Ineffective Cardioversion
Etiology
Inadequate energy output
Rise in the defibrillation threshold
Lead fracture
Insulation breakage

39. Electromagnetic Interference
Can interfere with function of pacemaker or ICD
Device misinterprets the EMI causing
Rate alteration
Sensing abnormalities
Asynchronous pacing
Noise reversion
Reprogramming

40. Electromagnetic Interference
Examples
Metal detectors
Cell phones
High voltage power lines
Some home appliances (microwave)

41. Electromagnetic Interference
Intensity of electromagnetic field decreases inversely with the square of the distance from the source
Newer pacemakers and ICDs are being built with increased internal shielding

42. Future ICD Technology Enhanced automaticity:
Device software that suggests programming options to the clinician based on the patient’s history and demographics
Continued reductions in device size:
Will require advancements in battery, capacitor and circuitry technology and/or decreasing the delivered energy output.

43. Future ICD Technology Enhanced diagnostics: Enhanced lead technology:
Monitoring of the progression of both arrhythmias and concomitant cardiac conditions
Enhanced lead technology:
Thinner leads with increased diagnostic capabilities, e.g., pressure sensing.
Patient follow-up modifications:
Broadly available programmer technology that enables remote transfer of data, reducing the need for in-clinic visits.

44. Thank you