1. Advance EP Training
April/24/2011
Basic ICD Treatment
張坤正 醫師
中國醫藥大學 內科副教授
中國醫藥大學附設醫院 心臟內科主任

2. ICD Concepts
ICD Automated Functions
Troubleshooting

3. ICD Concepts
Overview
• Evolution of ICDs
• The ICD System
• Components
– Device
• Battery, Capacitors & Voltage
• Circuitry
• Connector Blocks
– Leads
• Transvenous & Epicardial
• Electrical Design
• Connectors: IS-1 & DF-1
– Programmer

4. The Evolution of ICDs

5. ICD Evolution
1970
• Patent granted for first
totally implantable
defibrillator
• System used an
intracardiac catheter and
SQ patch with detection
via RV pressure transducer
Michael Mirowski (1924-1990)

6. ICD Evolution
• 1947 First human internal defibrillation
• 1956 First human external defibrillation
• 1969 First external canine prototype tested
• 1970 First implantable prototype (895 g)
• 1975 First implantable Defib in canines (250 g)
• 1980 First human implant @ Johns Hopkins
• 1985 ICD market released (350 units)

7. ICD Evolution
• 1991 Non thoracotomy lead systems
• 1995 Pectoral ICD systems
• 1997 ICD & DDD
• 1998 ICD & DR
• 1999 ICD & Atrial Defibrillation
• 2001 ICD & Resynchronization Therapy

8. THE ICD SYSTEM

9. The ICD System
How it Works
* Animation

10. The ICD System
How it Works
Atrium & Ventricle
Ventricle • Bradycardia sensing
• VT prevention • Bradycardia pacing
• Antitachycardia pacing • Antitachycardia
pacing
• Cardioversion
• Defibrillation

11. ICD
Device Components

12. ICD
Device Components

13. ICD
How High Voltage Is Created
Battery – Provides low voltage energy
c
Transformer – Multiplies Voltage
c
Capacitor – Stores high energy for use
c
High Voltage Shock – Delivered on
demand

14. ICD
How High Voltage Is Created
For Pacing Pacing
Voltage Voltages
Battery Multiplier
3.2 and
Volts High High Energy
Transformer
Voltage Shocks
For Defibrillation
Capacitor (Up to 800 Volts)

15. ICD
Battery Depletion

16. Battery & Charge Time Relationship
Battery DOWN
Both can Indicate
Elective Replacement
(ERI)
Charge Time UP

17. Battery & Charge Time Relationship

18. Battery & Charge Time Relationship
Battery Voltage & Charge Time in an optimized ICD battery

19. The Importance of Charge Time
10 Seconds of VF
The longer the charge time, the
longer this rhythm continues.

20. ICD
Connector Block

21. ICD
Connector Block

22. Components
ICD Connector Blocks

23. Today’s Current® DR RF Header (6 set screws)
New DF4 DR Header (2 set screws)
23

24. COMPONENTS
High Voltage Leads

25. High Voltage Leads
Epicardial
Placed directly on the epicardium of the heart.
Transvenous
Introduced into the heart through a vein.

26. High Voltage Leads

27. High Voltage Leads
Types of Transvenous Leads
Transvenous
Passive
Active
No
Fixation

28. Endocardial Lead Systems
Passive Fixation (Tines)
Active Fixation (Screw)

29. Transvenous Leads
Placement
Single Coil Dual Coil

30. Distal Coil
Proximal Coil
Connector
Pins

31. High Voltage Leads
Typical Transvenous Lead

32. Transvenous Lead
Steroid Tip
*Steroid not available in all leads

33. Transvenous Lead
Steroid Tip
Benefits of Steroid:
• Reduces acute Trauma and
Inflammation
• Rapid Tissue Damage Repair
• Reduced Fibrosis
*Steroid not available in all leads

34. Transvenous Lead
Lead Design
Optimal Tissue
Contact
*Steroid not available in all leads

35. Electrical Design

36. Lead Electrical Design
Circuits
• High Voltage Leads can have 2 Circuits:
PACING & SENSING
SHOCKING

37. Lead Electrical Design
Circuits
PACING & SENSING
Bipolar

38. Lead Electrical Design
Pacing/Sensing Circuit
• The electrical circuit for
pacing and sensing
includes:
•Cathode – negative
electrode (Tip)
•Anode: positive electrode
(Ring or Coil)
Bipolar
Configuration

39. Lead Electrical Design
Circuits
PACING & SENSING
Bipolar True vs. Integrated

40. Polarity
Pacing/Sensing Circuit
Bipolar
uses dedicated ring can as anode
Integrated Bipolar
uses RV Coil can as anode

41. Polarity
Pacing/Sensing Circuit

42. Lead Electrical Design
Circuits
PACING & SENSING
Bipolar True vs. Integrated
SHOCKING
High Voltage
Coils

43. Polarity
Shocking Circuit
Single Coil
• 1 high voltage coil per lead:
- RV (Right Ventricle)
- Other extra HV Coils/Patches
• 1 or 2 Connector Pins
- (HV only or P/S + HV)
Dual Coil
• 2 High Voltage coils per lead:
- RV + SVC
• 3 Connector Pins (P/S + 2 HV)

44. High Voltage Leads
Connector Pins
Pace / Sense Connection = IS-1
(International Standard)
High Voltage Defibrillation Connections = DF-1
(Defibrillation Standard)

45. Shocking Circuit
Vectors
• The pathway in which high energy is delivered
• Determined by electrodes used:
– HVA = active device
– HVB = RV Coil
– HVX = optional HV electrode (such as an SVC Coil)
Example: A > B A
(Active Can)
B
(RV HV Coil)

46. Shocking Circuit
Vectors
Example: A > B
(Active Can > RV HV Coil)

47. Shocking Circuit
Vectors
Example of Dual Coil: AX > B
(Active Can + SVC HV Coil > RV HV Coil)

48. Shocking Circuit
Vectors
A>B AX > B

49. COMPONENTS
Programmer

50. ICD Automated Functions

51. ICD Automated Functions
Overview
• Sensing • Therapy
–The EGM Signal –Tachyarrhythmia
–The Sensing Circuit
• Anti-tachycardia Pacing Low
–Marker Channels (ATP) Power
• Detection • Cardioversion (Non-
committed)
–Suspension (Magnet)
• Defibrillation (Committed)
–Rate & Duration
(NID) –Bradyarrhythmia
–Detection Zones • Pacing Modes
–SVT Discrimination • Parameters
• Single Chamber • Other Brady Therapies
• Dual Chamber
–Redetection

52. ICD Automated Functions
Sensing

53. Sensing
• Sensing - what the device “sees”
• Electrical Activity - what the
device is looking for
• Lead – contains the ‘eyeball’ of
the device

54. Sensing
True vs. Integrated Bipolar
• Range of ‘eyeball’ is determined by
polarity
True Bipolar Sensing Integrated Bipolar Sensing
Tip-to-ring Tip-to-coil
Smaller surface area Larger surface area
More “localized” sensing Broader sensing area

55. Sensing
•The ‘eye’ of the device
– Constantly watches for
electrical activity
– Sees or Senses all
electrical signals that pass
– Signal produced by a
passing electrical wave is
called an Intracardiac
Electrogram (EGM)

56. SENSING
The Intracardiac Electrogram EGM

57. Sensing
• Sensing is:
–The process of identifying cardiac
depolarizations from an intracardiac
electrogram

58. Sensing
The EGM Signal
• The signal from a depolarization wave passing between sensing electrodes
Processed by
Depolarization Wave Device

59. The EGM Signal
• Measured by:
– Amplitude
• Peak-to-peak measurement (height)
of deflection
• Measured in Millivolts (mV)
– Slew Rate
• Speed of deflection change over time
• Measured in volts per second (V/s)

60. The EGM Signal
Amplitude
• Measured Peak-to-Peak
Typical Ventricular EGM
• >5 mV for optimal sensing

61. The EGM Signal
Slew Rate
• Measures Peak-to-Peak
change in voltage over time
• R >.75 volts/sec for optimal
sensing
dV
Slew Rate =
[V/s] dt
Typical Ventricular EGM

62. The EGM Signal
Fields
• Nearfield
– Electrodes are close in range
• EGM Source = Tip-to-Ring / Tip-to-Coil
– Commonly a narrow signal (less myocardium in range)
– Used for arrhythmia detection
• Devices are hardwired to nearfield for detection

63. The EGM Signal
Nearfield
EGM Source = Tip-to-Ring / Tip-to-Coil
Tip-to-Ring Tip-to-Coil
(Bipolar) (Integrated
Bipolar)

64. The EGM Signal
Nearfield
Morphology
Comparison
SINUS
RHYTHM VT
EGM Source = Tip-to-Ring / Tip-to-Coil

65. The EGM Signal
Fields
•Nearfield
– Electrodes are close in range
•EGM Source = Tip-to-Ring / Tip-to-Coil
– Narrow signal – less myocardium in range
– Used for arrhythmia detection
•Farfield
–Electrodes are further in range
•EGM Source = Variable
–More myocardium covered in range
–Can resemble surface EKG

66. The EGM Signal
Farfield
EGM Source = Variable
Can-to-RV Coil RV Coil-to-SVC
(HVA to HVB) Coil
(HVB to HVX)

67. The EGM Signal
Farfield
Morphology
Comparison
SINUS
RHYTHM VT
EGM Source = Variable

68. SENSING
The Sensing Circuit

69. The Sensing Circuit
• Upon being ‘seen,’ a signal is transported through
the sensing circuit

70. The Sensing Circuit
The Amplifier

71. The Sensing Circuit
The Bandpass Filter

72. The Sensing Circuit
Rectifier

73. The Sensing Circuit
Level Detector

74. The Sensing Circuit
Level Detector

75. The Sensing Circuit

76. The Sensing Circuit

77. Sensitivity
• Minimum amplitude of electrical signal that
registers as a sensed event
– Set in Millivolts (mV)
– Programmable Setting

78. Sensitivity
Programmed
If set at .15 mV

79. Sensitivity
Programmed
If set at .3 mV
T-wave Not
Sensed

80. Sensitivity
Auto-Adjusting

81. Sensitivity
Auto-Adjusting
• Allows sensing of fine VF waves
• Prevents sensing of T-waves, cross-chamber
events, and pacing artifacts

82. Auto-Adjusting Sensitivity
Decay Constant

83. Threshold Start
Max R- wave
Max R-wave amplitude
amplitude measured at 7
measured at 4
mV
mV
Threshold Start
R- wave is set to 50% of
Sensed measured R-
wave or 3 mV
2 mV 3 mV
Maximum
Sensitivity
Ventricular
Sensed Refractory Sensed Refractory

84. Decay Delay
• The Decay Delay holds the sensitivity
threshold at the starting value for a
programmable amount of time
60 ms
0 ms
R- T-
wave wave

85. Question?
What are the consequences of
undersensing?
• Failure to sense VF, therefore, no therapy
initiated
• Failure to treat VT that can accelerate to VF
• Can be fatal

86. Question?
What are the consequences of
oversensing?
• Inappropriate therapies
• Potential for inducing fatal arrhythmias
• Patient suffering due to inappropriate
therapy

87. SENSING
Marker Channels™

88. Marker Channel™
• Display:
– Pace/Sense annotations
– ICD functional annotations:
• Sensing
• Detection
• Therapy
• Other information
* in Medtronic devices

89. ICD Automated Functions
Detection

90. Question?
What does “Detection” mean?
A device defined arrhythmia is present
based on what is sensed.

91. Detection
• Confirms a sensed rhythm as an
arrhythmia based on:
– Rate
– Duration

92. Detection
Detection Rate
• Measured in:
–Beat-to-beat intervals (milliseconds), or
–Beats-per-minute (BPM)
• Classifies rhythm by detection zone:
–VT = Ventricular Tachycardia
–VF = Ventricular Fibrillation
• Programmable in ranges of rates
Example: VT = 162 bpm – 188 bpm
VF = 188 bpm and faster

93. Detection
Detect Duration
• Measured in:
– Number of intervals to detect (NID), or
– Length of time to detect
• Programmable by:
– Beat or interval counters
• Consecutive
ex: 16 beats within the detect zone
• Probabilistic (percentage or fraction)
ex: 12 out of 16 beats within the detect zone
– Time in seconds

94. Detection
Consecutive Counter
Used for detection of VT

95. Detection
Probabilistic Counter
NID =
12/16

96. Detection
Detect Duration
Non-Sustained: Duration not met / No Detection
Sustained: Duration met / Detection Occurs

97. Question?
What if the fast, sustained ventricular
rhythm is the result of an SVT?

98. SVT Discriminators
•SVT Discriminators:
– Prevent detection of tachyarrhythmias
caused by the presence of an SVT
– Prevent inappropriate, unnecessary therapy
due to rapid SVT conduction
– Are present in some form in most ICDs

99. SVT Discriminators
•Discriminate based on:
– Waveform morphology
• EGM Width (single chamber)
• Wavelet
– Onset of arrhythmia
– Stability of arrhythmia
– Relationship between P- and R-waves
(dual chamber / requires an atrial lead)

100. SVT Discriminators
Waveform Morphology
•Measures and stores the QRS
characteristics of a normal sinus beat
•Identifies SVT vs. VT based on the QRS
changes that occur in most VTs
SINUS VT
RHYTHM

101. Classification: MD Morphology
Discrimination
Sinus
Supra-Ventricular
Ventricular
Electrical wavefronts generated by focus approach electrodes from
different directions depending on the focus location.

102. SVT Discriminators
Wavelet
•Match Threshold Programming
– Lower %
• More likely to withhold appropriately; less likely to detect true VT
– Higher %
• Less likely to appropriately withhold; more likely to detect true VT

103. SVT Discriminators
Onset
•Based on the premise that most VTs
are characterized by a sudden onset
•Evaluates the acceleration of the
ventricular rate
•Discriminates between:
–Gradual rate increase
–Abrupt rate increase
•Determines VT present if rate
increase is abrupt

104. SVT Discriminators
Onset
• When On:
– Averages 4 beats and compares with an
average of previous 4 (multiplied by
programmed Onset Percentage)
• Onset met if recent average is less
than previous

105. SVT Discriminators
Onset
• Onset Percentage = 81%
530ms X 81% = 430ms ≠ 460ms = Onset
430ms Not Met
* in Medtronic devices

106. SVT Discriminators
Stability
•Based on the premise that AF conducts
irregularly to the ventricles
(and VT is a stable, regular rhythm)
•Discriminates regular from irregular
intervals within a detect zone

107. SVT Discriminators
Stability
Stability = 50 ms
Varies >50 ms from Unstable
previous 3

108. SVT Discriminators
Dual Chamber
• Considers P and R relationship to
discriminate SVT from VT
• Dual Chamber (requires an atrial and ventricular lead)
• Can be used in conjunction with other
discriminators

109. Optimized DR Discriminators
Bigeminal Avoidance
Ventricular frequency >
VT detection
Compare atrial &
ventricular frequency
V<A V=A V>A
SVT
On
Stability VT
Morphology 40 ms
Off
45% Morphology
Onset
5 out of 8 AVA 45%, 5/8
Passive
80 ms ATU On
Any

110. SVT Discriminators
PR Logic™
•What it looks for:
– Atrial Fibrillation / Flutter
– Sinus Tachycardia
– Other 1:1 SVTs (such as AVNRT)
•How it works:
– Analyzes:
• Pattern (P:R wave relationship)
• AV Association
• Rate
• Regularity (R waves)

111. PR Logic™
Pattern
•Distinguishes SVTs by analyzing P and R-wave:
– Pattern: number and position of atrial events relative to ventricular events

112. PR Logic™
Example: Sinus Tachycardia

113. PR Logic™
Example: Atrial Fibrillation

114. PR Logic™
Example: AVNRT (Other 1:1 SVTs)
Junctional
Zone

115. Question?
What about far-field R-wave sensing
in the atrial channel?

116. PR Logic™
Far-field R-wave Sensing
•Algorithm identifies and withholds
therapy for:
– Consistent, short-long pattern

117. Question?
What happens when a magnet is
applied over an ICD?

118. Tachy Detection
Magnet Mode
• ICDs of different manufacturers respond to
magnets differently
• Use when:
– EMI is present (surgery, TENS, etc.)
– Temporary suspension is preferred over permanent
programming
– Therapy is temporarily not desired

119. ICD Automated Functions
Therapy

120. Question?
Can you name some therapies delivered
by an ICD?

121. ICD Therapies
• ICD Therapy
– Low Power (Pacing Therapies)
• Anti-tachycardia Pacing (ATP)
• Bradyarrhythmia Pacing
– High Power (Shock Therapies)
• Cardioversion
• Defibrillation

122. Anti-Tachycardia Pacing

123. Anti-Tachycardia Pacing
Re-entry ATP delivered at a rate Subsequent Pulse:
initiated faster than Wavefronts collide
tachyarrhythmia. closer to re-entry
Wavefronts collide. circuit
Subsequent Pulses: Arrhythmia
Wavefronts collide terminated
even closer to re-
entry circuit

124. Anti-Tachycardia Pacing
•Has programmable:
– Sequences – the number of times ATP will be
applied upon re-detection

125. Anti-Tachycardia Pacing
•Has programmable:
–Pulses – the number of pulses per sequence

126. Anti-Tachycardia Pacing
•Has programmable:
– Sequences – the number of times ATP will be applied
upon re-detection (max = 10 in most)
–Pulses – the number of pulses per sequence
(1-15)
–Rate of pulses delivered (percent or ms)

127. Anti-Tachycardia Pacing
• Types:
–Burst
•A series of pacing pulses delivered at
equal intervals
•Interval decrement per sequence

128. Anti-Tachycardia Pacing
Burst

129. Anti-Tachycardia Pacing
•Types:
–Burst
•A series of pacing pulses delivered at equal
intervals
•Interval decrement per sequence
–Ramp
• A series of pacing pulses delivered at ever
decreasing intervals
• Adds a pulse per sequence

130. Anti-Tachycardia Pacing
Ramp

131. Anti-Tachycardia Pacing
Burst and Ramp Comparison
Programmed Values: Programmed Values:
Number of S1 Pulses = 4 Number of S1 Pulses = 4
Number of Sequences = Number of Sequences = 4
4 R-S1% = 91%
R- S1% = 91% Decrement* = 10 ms
Decrement* = 10 ms * Decrement between pulses
* Decrement between sequences * Adds a pulse per sequence

132. ICD Therapies
•Tachyarrhythmia Therapy
–Anti-Tachycardia Pacing (ATP)
Low
Power
•Pacing pulses delivered at a rate faster
than the rhythm detected
•Can successfully terminate re-entrant
tachycardias
–Cardioversion (CV)
High
Power
•Non-committed shock therapy
(must synchronize to an R-wave to be
delivered)
•Designed to treat re-entrant
tachycardias

133. Cardioversion
•Delivers shock on an R-wave
•Aborts if synchronization cannot be
obtained due to arrhythmia termination

134. Cardioversion
Programming

135. ICD Therapies
•Tachyarrhythmia Therapy
–Anti-Tachycardia Pacing (ATP) Low
Power
•Pacing pulses delivered at a rate faster than the
rhythm detected
•Can successfully terminate re-entrant tachycardias
–Cardioversion (CV) High
Power
•A non-committed shock (must synchronize to an
R-wave to be delivered)
•Designed to treat organized tachyarrhythmias
–Defibrillation Shock High Power
•A shock delivered to the heart to terminate a
tachyarrhythmia

136. ICD Therapy
Benefits of Tiered Therapy
VT
FVT
VF

137. Defibrillation
Programming
*Medtronic Programming
Screen

138. Question?
When does the device call a therapy
a success?

139. ICD Therapies
Termination/Redetection
•“8 to terminate” rule
–8 sinus and/or paced beats outside the
slowed programmed detection zone
* in Medtronic devices

140. ICD System Troubleshooting

141. Troubleshooting
Overview
•ICD System Issues
–Lead System & Connections
–Device
–Other Issues (Patient, EMI)

142. ICD SYSTEM ISSUES
Lead Systems & Connections

143. Question?
In an ICD System, what
component is generally known to
be the source of most issues?
a. device
b. lead

144. ICD System Issues
Leads
• Points of Failure
– Acute (common suspects)
• Connector
• Lead Dislodgement/Perforation

145. ICD System Issues
Leads
Points of Failure
– Chronic (common suspects: High points of stress/pressure)
Lead fracture (commonly exhibits HIGH impedance/resistance)
Lead insulation break (commonly exhibits LOW
impedance/resistance)

146. ICD System Issues
Points of Failure
– Acute (common suspects)
Connector
What kinds of things can go wrong here?

147. ICD System Issues
Connector
Can you identify a problem?
Set screw is obstructing the bore

148. ICD System Issues
Connector
What might happen if a lead is
connected?

149. ICD System Issues
Connector
What is going on here?
Set Screw Noise

150. ICD System Issues
• Points of Failure
– Acute (common suspects)
• Connector
Lead dislodgement/perforation
How do we know when this occurs?

151. ICD System Issues
Lead Dislodgement
Common signs
– Intermittent or loss of capture
– Intermittent or loss or sensing
– Inappropriate therapy during SVT
(in this example due to atrial lead dislodgement)
Atrial Dislodgement

152. ICD System Issues
Lead Dislodgement
Can you identify the dislodged
lead(s)?

153. ICD System Issues
Lead Dislodgement
• Avoiding dislodgements
– Ensure sufficient slack in lead
– Use suture sleeves
– Check lead tip stability during implant

154. ICD System Issues
Lead Perforation
• Occurs when:
– Lead tip exits the heart, through the heart

155. ICD System Issues
Lead Perforation
•Diagnosing
– Can be seen on x-ray
– Definitive by Echo
– Threshold and lead impedance may remain
unchanged (due to possible continuous contact with tissue
outside the heart)
•Possible patient symptoms
– Change in pressure
– Cardiac tamponade
– Dyspnea

156. ICD System Issues
• Points of Failure
– Acute (common suspects)
• Connector
• Lead dislodgement/perforation
– Chronic (common suspects: High points of stress/pressure)
Lead fracture (commonly exhibits HIGH impedance)

157. ICD System Issues
Can you identify a problem?
1st Rib-Clavicle Crush (lead fracture)

158. ICD System Issues
Lead Fracture
Lead Crush
1st Rib & Clavicle Crush

159. ICD System Issues
Lead Fracture
Can you identify the fracture?

160. ICD System Issues
Lead Fracture
• Common behavior
– Erratic sensing
– Intermittent or loss of capture
– High lead impedance

161. ICD System Issues
Lead Fracture
Example

162. ICD System Issues
• Points of Failure
– Acute (common suspects)
• Connector
• Lead dislodgement/perforation
(common suspects: high points
– Chronic
of stress/pressure)
Lead fracture (commonly exhibits HIGH impedance)
Lead insulation break (commonly exhibits
LOW impedance)

163. ICD System Issues
Insulation Break
• Common Behavior
– Lead impedance
• Low
• Can be intermittent
– Capture threshold
• Sudden rise or loss
• Can be intermittent
– Sensing
• Over/undersensing
• Can be intermittent Coaxial Inner
Insulation Breach

164. ICD System Issues
Insulation Break
Example

165. ICD SYSTEM ISSUES
Device

166. ICD System Issues
Device
• Common device issues:
– Long charge times
– Battery depletion
• Elective Replacement (ERI)
• End of Life (EOL)
– Inappropriate programming
Acceleration
Over/Undersensing
Output

167. ICD System Issues
Device
Can you identify a problem?
T-wave oversensing

168. ICD System Issues
Can you identify the problem?
Device
*Medtronic Programming Undersensing

169. ICD System Issues
Device
Can you identify the problem?
Undersensing

170. Infection/Erosion/Allergy

171. Allergy/Infection/Allergy

172. Infection/Erosion/Allergy
Allergy Testing
Allergy Test Metals
(included in kits)
Allergy Test Kit Contents:
Polyurethane
Silicone
Titanium
Platinum Iridium
Polysulfone
Epoxy
Gold-sputtered devices

173. Abandoned Leads
• Chatter between active and abandoned leads
may cause inappropriate therapy

174. Electromagnetic Interference
(EMI)
• The sensing of electrical signals other than
those produced by the heart
60 Hz (oversensing)

175. Test Your Skills
What might you suspect from this EGM?

176. Case Study (Noise)
• Male 62 years
• ICD Implant for VT/VF
• Patient got 11 shocks

177. Fast Path Summary

178. Trends: Signal Amplitude

179. Trends: Lead Impedance
Impedance Decrease

180. Appropriate or Inappropriate Therapy?

181. Episode 52
A/V lead 皆有
noise

182. Case study (Morphology Change)
• Female 72 years old
• ICD for VT episodes
• Standard follow-up patient didn’t feel
anything.

183. FastPath Summary

184. Episode Directory

185. Episode 1: Appropriate or Inappropriate Therapy?
Morphology score low

186. Diagnostics

187. Therapy

188. MD Auto Update
Morphology auto update score increase to 100

189. Episode 3: Correct Diagnosis?
SVT Diagnosis

190. Diagnostics
After morphology update Correct Discreamation is SVT

191. CMUH

192. CMUH

193. Indications for ICD Therapy

194. Implantable Cardioverter-Defibrillators
I IIa IIb III
IIb III ICD therapy is indicated in patients who are survivors of
cardiac arrest due to ventricular fibrillation or
hemodynamically unstable sustained VT after evaluation
to define the cause of the event and to exclude any
completely reversible causes.
I IIa IIb III
ICD therapy is indicated in patients with structural heart
disease and spontaneous sustained VT, whether
hemodynamically stable or unstable.
I IIa IIb III
ICD therapy is indicated in patients with syncope of
undetermined origin with clinically relevant,
hemodynamically significant sustained VT or VF induced
at electrophysiological study.
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

195. Implantable Cardioverter-Defibrillators
I IIa IIb III
IIb III ICD therapy is indicated in patients with LVEF less than or
equal to 35% due to prior MI who are at least 40 days
post-MI and are in NYHA functional Class II or III.
I IIa IIb III ICD therapy is indicated in patients with nonischemic DCM
who have an LVEF less than or equal to 35% and who are
in NYHA functional Class II or III.
I IIa IIb III
IIb III ICD therapy is indicated in patients with LV dysfunction
due to prior MI who are at least 40 days post-MI, have an
LVEF less than or equal to 30%, and are in NYHA
functional Class I.
I IIa IIb III ICD therapy is indicated in patients with nonsustained VT
due to prior MI, LVEF less than or equal to 40%, and
inducible VF or sustained VT at electrophysiological study.
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

196. Implantable Cardioverter-Defibrillators
I IIaIIbIII
ICD implantation is reasonable for patients with unexplained
syncope, significant LV dysfunction, and nonischemic DCM.
I IIaIIbIII ICD implantation is reasonable for patients with sustained VT and
normal or near-normal ventricular function.
I IIaIIbIII ICD implantation is reasonable for patients with HCM who have 1
or more major† risk factors for SCD.
ICD implantation is reasonable for the prevention of SCD in
I IIaIIbIII patients with arrhythmogenic right ventricular
dysplasia/cardiomyopathy (ARVD/C) who have 1 or more risk
factors for SCD.
I IIaIIbIII ICD implantation is reasonable to reduce SCD in patients with long-
QT syndrome who are experiencing syncope and/or VT while
receiving beta blockers.
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.
† See Section 3.2.4, “Hypertrophic Cardiomyopathy,” in the full-text guidelines for definition of major risk factors.

197. Implantable Cardioverter-Defibrillators
I IIaIIbIII ICD implantation is reasonable for nonhospitalized
patients awaiting transplantation.
I IIaIIbIII ICD implantation is reasonable for patients with Brugada
syndrome who have had syncope.
I IIaIIbIII ICD implantation is reasonable for patients with Brugada
syndrome who have documented VT that has not resulted
in cardiac arrest.
I IIaIIbIII ICD implantation is reasonable for patients with
catecholaminergic polymorphic VT who have syncope
and/or documented sustained VT while receiving beta
blockers.
I IIaIIbIII
ICD implantation is reasonable for patients with cardiac
sarcoidosis, giant cell myocarditis, or Chagas disease.
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

198. Implantable Cardioverter-Defibrillators
I IIaIIbIII ICD therapy may be considered in patients with nonischemic
heart disease who have an LVEF of less than or equal to
35% and who are in NYHA functional Class I.
I IIa IIbIII
IIbIII ICD therapy may be considered for patients with long-QT
syndrome and risk factors for SCD.
I IIaIIbIII ICD therapy may be considered in patients with syncope
and advanced structural heart disease in whom thorough
invasive and noninvasive investigations have failed to define
a cause.
I IIaIIbIII
ICD therapy may be considered in patients with a familial
cardiomyopathy associated with sudden death.
I IIaIIbIII
ICD therapy may be considered in patients with LV
noncompaction.
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

199. Implantable Cardioverter-Defibrillators
I IIa IIb III ICD therapy is not indicated for patients who do not have
a reasonable expectation of survival with an acceptable
functional status for at least 1 year, even if they meet ICD
implantation criteria specified in the Class I, IIa, and IIb
I IIa IIb III recommendations above.
ICD therapy is not indicated for patients with incessant
VT or VF.
I IIa IIb III ICD therapy is not indicated in patients with significant
psychiatric illnesses that may be aggravated by device
implantation or that may preclude systematic follow-up.
I IIa IIb III ICD therapy is not indicated for NYHA Class IV patients
with drug-refractory congestive heart failure who are not
candidates for cardiac transplantation or cardiac
resynchronization therapy defibrillators (CRT-D).
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

200. Implantable Cardioverter-Defibrillators
I IIa IIb III ICD therapy is not indicated for syncope of undetermined
cause in a patient without inducible ventricular
tachyarrhythmias and without structural heart disease.
ICD therapy is not indicated when VF or VT is amenable
I IIa IIb III
to surgical or catheter ablation (e.g., atrial arrhythmias
associated with the Wolff-Parkinson-White syndrome, RV
or LV outflow tract VT, idiopathic VT, or fascicular VT in
the absence of structural heart disease).
I IIa IIb III ICD therapy is not indicated for patients with ventricular
tachyarrhythmias due to a completely reversible disorder
in the absence of structural heart disease (e.g., electrolyte
imbalance, drugs, or trauma).
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

201. ICDs in Pediatric Patients and Patients With
Congenital Heart Disease
I IIa IIb III ICD implantation is indicated in the survivor of
cardiac arrest after evaluation to define the cause of
the event and exclusion of any reversible causes.
I IIa IIb III
ICD implantation is indicated for patients with
symptomatic sustained VT in association with
congenital heart disease who have undergone
hemodynamic and electrophysiological evaluation.
Catheter ablation or surgical repair may offer
possible alternatives in carefully selected patients.
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

202. ICDs in Pediatric Patients and Patients With
Congenital Heart Disease
I IIa IIb III
IIb III ICD implantation is reasonable for patients with congenital
heart disease with recurrent syncope of undetermined origin
in the presence of either ventricular dysfunction or inducible
ventricular arrhythmias at electrophysiological study.
I IIa IIb III ICD implantation may be considered for patients with
recurrent syncope associated with complex congenital heart
disease and advanced systemic ventricular dysfunction
when thorough invasive and noninvasive investigations have
failed to define a cause.
I IIa IIb III All Class III recommendations found in Section 3 of the full-
text guidelines, “Indications for Implantable Cardioverter-
Defibrillator Therapy,” apply to pediatric patients and
patients with congenital heart disease, and ICD implantation
is not indicated in these patient populations.
All primary SCD prevention ICD recommendations apply only to patients who are receiving optimal medical therapy and have reasonable expectation of
survival with good functional capacity for more than 1 year.

203. Major Implantable Cardioverter-Defibrillator
Trials for Prevention of Sudden Cardiac Death
Trial Year Patients LVEF Additional Study Hazard 95% CI p
(n) Features Ratio*
MADIT I 1996 196 < 35% NSVT and EP+ 0.46 (0.26-0.82) p=0.009
MADIT II 2002 1232 < 30% Prior MI 0.69 (0.51-0.93) p=0.016
CABG-Patch 1997 900 < 36% +SAECG and CABG 1.07 (0.81-1.42) p=0.63
DEFINITE 2004 485 < 35% NICM, PVCs or NSVT 0.65 (0.40-1.06) p=0.08
DINAMIT 2004 674 < 35% 6-40 days post-MI 1.08 (0.76-1.55) p=0.66
and Impaired HRV
SCD-HeFT 2006 1676 < 35% Prior MI of NICM 0.77 (0.62-0.96) p=0.007
AVID 1997 1016 Prior cardiac NA 0.62 (0.43-0.82) NS
arrest
CASH† 2000 191 Prior cardiac NA 0.766 ‡ 1-sided
arrest p=0.081
CIDS 2000 659 Prior cardiac NA 0.82 (0.60-1.1) NS
arrest, syncope
* Hazard ratios for death from any cause in the ICD group compared with the non-ICD group. Includes only ICD and amiodarone patients from CASH.
‡CI Upper Bound 1.112 CI indicates Confidence Interval, NS = Not statistically significant, NSVT = nonsustained ventricular tachycardia, SAECG = signal-averaged
electrocardiogram.
Epstein A, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities. J Am Coll Cardiol 2008; 51:e1–62. Table 5.

204. Comparison of Medical Therapy, Pacing, and Defibrillation in
Heart Failure (COMPANION) Trial
• 1520 patients with NYHA Class III or IV HF, ischemic
cardiomyopathy (ICM) or nonischemic cardiomyopathy
(NICM) and QRS ≥ 120 ms
• Randomized 1:2:2 to optimal pharmacological therapy
(OPT) alone or in combination with cardiac
resynchronization therapy with either a pacemaker (CRT-P)
or pacemaker-defibrillator (CRT-D)
• Both device arms significantly ↓ combined risk of all-cause
hospitalization and all-cause mortality by ~20% compared
with OPT
• CRT-D ↓ mortality by 36% compared with OPT (p=0.003)
• Insufficient evidence to conclude that CRT-P inferior to
CRT-D
Bristow MR, Saxon LA, Boehmer J, et al. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced
chronic heart failure. N Engl J Med 2004;350:2140-50.

205. Implantable Cardioverter-Defibrillators and Prevention of
Sudden Cardiac Death in Hypertrophic Cardiomyopathy
• Multicenter registry study of implanted ICDs in 506
unrelated patients with HCM @ high risk for SCD (family
hx of SCD, [septal thickness ≥ 30 mm], NSVT, syncope)
• Mean patient age 42 years (SD=17) and 87% had no or
only mildly limiting symptoms
• Appropriate ICD discharge rates were 11% per year for
2o prevention and 4% per year for 1o prevention
• For 1o prevention, 35% of patients with appropriate ICD
interventions had undergone implantation for only 1 risk
factor
Maron BJ, Spirito P, Shen WK, et al. Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic
cardiomyopathy. JAMA 2007;298:405-12.

206. Multicenter Automatic Defibrillator Implantation Trial
II (MADIT II)
• 1232 patients ≥ 1 month post-MI and LVEF ≤ 30%
• Randomized to ICD (n=742) or medical therapy (n=490)
• No spontaneous or induced arrhythmia required for
enrollment
• 6% absolute and 31% relative risk ↓ in all-cause mortality
with ICD therapy (p=0.016)
Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced
ejection fraction. N Engl J Med 2002;346:877-83.

207. Sudden Death in Heart Failure
(SCD-HeFT) Trial
• 2521 patients with NYHA Class II or III HF, ICM, or
NICM and LVEF ≤ 35%
• Randomized to
1) conventional rx for HF + placebo;
2) conventional rx + amiodarone; or
3) conventional rx + conservatively programmed shock-
only single lead ICD
• No survival benefit for amiodarone
• 23% ↓ in overall mortality with ICD therapy
• Absolute ↓ in mortality of 7.2% after 5 y in the overall
population
Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med
2005;352:225-37.

208. Defibrillator in Acute Myocardial Infarction
(DINAMIT) Trial
• 674 patients 6 to 40 days post-MI with LVEF ≤ 35% and
impaired cardiac autonomic function
• Randomized to ICD therapy (n=332) or no ICD therapy
(n=342)
• Arrhythmic death ↓ in ICD group, but ↑ in nonarrhythmic
death (6.1% per year vs. 3.5% per year, HR 1.75 (95%
CI 1.11 to 2.76; p=0.016)
• No difference in total mortality
Hohnloser SH, Kuck KH, Dorian P, et al. Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction.
N Engl J Med 2004;351:2481-8.

209. Defibrillators in Nonischemic Cardiomyopathy
Treatment Evaluation (DEFINITE) Trial
• 458 patients with NYHA Class I to III, NICM, LVEF ≤
35% and premature ventricular contractions (> 10/h) or
NSVT
• Randomized to standard medical rx alone or in
combination with single-chamber ICD
• Strong trend toward ↓ all-cause mortality with ICD
therapy, although not statistically significant (p=0.08)
Kadish A, Dyer A, Daubert JP, et al. Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy. N Engl J
Med 2004;350:2151-8.

210. Notable Changes in 2008 ACC/AHA/HRS Guidelines
1. ICD recommendations are combined into a single list because of overlap between primary
and secondary indications.
2. Primary prevention ICD indications in nonischemic cardiomyopathy are clarified using data
from SCD-HeFT (i.e., ischemic and nonischemic cardiomyopathies and LVEF ≤35%, NYHA
II-III) for support.
3. Indications for ICD therapy in inherited arrhythmia syndromes and selected nonischemic
cardiomyopathies are listed.
4. MADIT II indication (i.e., ischemic cardiomypathy and LVEF ≤30%, NYHA I) is now Class I,
elevated from Class IIa.
5. EF criteria for primary prevention ICD indications are based on entry criteria for trials on
which the recommendations are based.
6. Emphasized primary SCD prevention ICD recommendations apply only to patients
receiving optimal medical therapy and reasonable expectation of survival with good
functional capacity for >1 year.
7. Independent risk assessment preceding ICD implantation is emphasized, including
consideration of patient preference.
8. Optimization of pacemaker programming to minimize unneeded RV pacing is encouraged.
9. Pacemaker insertion is discouraged for asymptomatic bradycardia, particularly at night.
10. A section has been added that addresses ICD and pacemaker programming at end of life.