ICD troubleshooting

Satyam Rajvanshi
ICD System
Troubleshooting

Word meaning
• ICD
– Intracardiac

Word meaning
• ICD
– Intracardiac cardioverter

Word meaning
• ICD
– Intracardiac cardioverter defibrillator

• ICD brief history
– 1947 First human internal defibrillation
– 1956 First human external defibrillation
– 1966 First ICD conception
– 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 – Mirowski et al
– 1985 ICD market released (350 units) – (FDA approval)

ICD: Conception 1966
Dr Mirowski

ICD: Conception 1966
Over-the-counter electronic components

ICD: First Human Implant 1980
Dr Winkle, Dr Mirowski, the first ICD patient, Dr Heilman

ICD: First Human Implant 1980
A transvenous lead in SVC and a ventricular patch lead

Word meaning
• Troubleshooting

Sensing Detection Therapy
ICD treats ventricular tachyarrhythmias

Sensing in ICD: A major challenge…
Sensing - process by which an ICD determines the timing of each
atrial or ventricular depolarization from electrogram signals.
A wide variation in the size of signals
• stable and large normal ventricular signals
• low amplitude VF signals

Sensing auto-adjust
Beat-to-beat auto-adjusting sensitivity

Sensing auto-adjust
Sinus rhythm – To avoid oversensing T waves
VF – To avoid undersensing

Detection
Algorithm by which ICD processes sensed signals to classify the
rhythm and determine if therapy should be delivered.
Up to 3 programmable rate detection zones to permit zone-
specific therapies for slower VT, faster VT, and ventricular
fibrillation (VF).
The minimum duration of tachycardia required for detection is
programmable, either in seconds or in number of ventricular
intervals required for detection.
The specific method used to count ventricular intervals
influences the sensitivity and specificity of VT detection

SVT-VT discriminators
Programmable subset of the VT/VF detection algorithm that
withholds ventricular therapy for SVT to improve specificity.
They usually differ from SVT detection algorithms used to mode-
switch during bradycardia pacing or to deliver atrial therapy
for atrial fibrillation or atrial flutter.

Confirmation or Reconfirmation
Brief process by which ICDs determine whether to deliver or
abort a shock after the high-voltage capacitor is charged.

Redetection
Process by which ICDs determine whether VT or VF detection
criteria remain satisfied after therapy is delivered.

Termination
Termination of a VT or VF episode occurs when the ICD
reclassifies the rhythm as sinus after VT or VF has been
detected.

Detection
Ventricular Fibrillation (VF)
• Rate cut-off (VF zone)
• Number of intervals for detection
(usually consecutive intervals not required; high sensitivity)

Detection
Ventricular Tachycardia (VT)
• Rate cut-off [VT zone(s)]
• Number of intervals for detection
• Detection Enhancement/SVT-VT Discriminators

Electrogram Morphology
• Current electrogram signal compared with stored normal
template
• Match percentage = 1 - (area of difference)
SVT-VT Discriminators

Stability
• To reduce inappropriate detection of atrial arrhythmias eg
atrial fibrillation (rhythm not “stable” i.e. variable cycle length)
• Each interval compared to previous intervals
• Count as VT if the difference  the programmed stability
interval i.e. VT is “stable”
VT detection interval: 500ms Stability 30ms

Onset
• To reduce inappropriate detection of sinus tachycardia
• Average of current 4 intervals is compared to average of
previous 4 intervals
Current average programmed
Previous average onset percentage
i.e. onset is “sudden” in VT


Lead noise discriminator
 Caused by pace-sense conductor fracture, loose
set screw, lead insulation breach.
 Therapy avoided by comparing near-field channel
(RV tip to RV ring) to far-field channel (RV tip to
Can/RV coil to Can)

* - AT may have sudden onset, weaker criteria

ICD troubleshooting
• Troubleshooting problems identified at routine follow-up

ICD troubleshooting
• Troubleshooting an ICD shock

ICD troubleshooting
• Troubleshooting an ICD shock
• Remote monitoring

TROUBLESHOOTING PROBLEMS
IDENTIFIED AT ROUTINE FOLLOW-UP

Battery depletion
Premature battery depletion
• Latest iterations of ICDs claim battery lifespan of more than 10 yrs
with 2 shocks per year and upto 40% pacing support

Battery depletion
• Causes related to pacing
– Unnecessary ventricular pacing
– High pacing outputs
– Lead insulation failure

Battery depletion
• Causes related to pacing
– Unnecessary ventricular pacing
– High pacing outputs
– Lead insulation failure
• Most common cause of asymptomatic battery depletion
– Repeated capacitor charging due to aborted shocks due to
repetitive nonsustained VT or oversensing due to lead-
connector problems
• Repeated shocks due to VT storm

Lead problems
Evaluation in all patients usually
• Electrograms from all electrodes on the lead
– Sensed amplitude (P/R)
– Any oversensing

Lead problems
• Pacing threshold, pacing impedance
– Impedance varies with manufacturer/lead type
– 200-2000 ohms

Lead problems
• Painless high voltage electrode impedance
– 25-75 ohms
– Review of periodic assessment

Lead problems
• Painless high voltage electrode impedance
Selective patients
• Radiography
• Stored episode electrograms, data logs, patient alerts
• Real time telemetry – provocative maneuvers

Undersensing VT/VF
Sustained Ventricular Arrhythmias Without ICD Therapy:
• Programming error
– VT rate limit is set above that of the clinical VT.
– Discrimainator inhibits therapy thinking it is SVT
• System component failure
– Lead failure - conducture fracture, insulation failure, decrease in
sensing characteristics of the lead
– Battery or capacitor failure – prolonged charge time

Inappropriate Shock
Tachycardia
Absent
(Oversensing)
Intracardiac
T/P wave
Double count
Extracardiac
EMI
Myopotentials
Present
(Inappropriate SVT
detection)

Tachycardia present
• VF? – Analyse EGM to verify
• VT? – Analyse EGM to differentiate SVT/VT

EGM to differentiate SVT/VT
• Single chamber ICD
– Unstable rhythm is more likely to represent AF,
– Gradual acceleration is more compatible with sinus tachycardia
– Sudden onset regular tachycardias – SVT (AVNRT, AT, Afl) or VT
• Compare morphology of far-field channel from sinus rhythm with the one
in arrhythmia
• Morphology of beats that immediately follow shocks should not be relied
on for comparison because of possible EGM distortion
• Beats that immediately follow ATP can be analysed

• ATP response
• In V=A Tachycardia, During ATP
– If AV dissociation – AT > AVNRT >> VT
– If retrograde AV blocks – AVNRT > VT
– Arrhythmia termination by ATP – supports VT >> AVRT, AVNRT
– If atrial acceleration to ATP (entrainment), then after ATP stops
• VAAV – AT
• VVA – VT
• VAV – Not helpful

• Dual chamber ICD
– Atrial sensing
• V>A vs. V<A
• PVC vs. PAC initiated
• If V=A, Driving chamber
– A-A followed by V-V vs. V-V followed by A-A

Appropriate Shock
• Single shock
• Multiple shocks

Appropriate Shock
• Single shock
• Multiple shocks
– Ineffective Initial shocks – High DFT
– Incessant VT
– VT Storm
– Appropriate shocks for AF – If AF defibrillation ‘ON’

VT storm
• Treat ischemia or other precipitating factors such as HF
• Judicious use of a magnet or inactivation of ICD therapy
• Pharmacological therapy for VT (e.g. β-blockers, amiodarone);
possible catheter ablation
• IABP or hemodynamic support for hypotension
• Replace electrolytes (K+, Mg2+)
• Left stellate ganglionic blockade in selected patients
• Identify specific diseases that may need specific therapy (e.g.
recurrent VT in Brugada syndrome - isoproterenol and
quinidine)

SYNCOPE WITH NO APPARENT
SHOCK

Is the ICD programming appropriate to the
patient needs?

Traditional/Older Concepts
 Quick detection: the longer the arrhythmia, the more likely a
patient to have symptoms e.g. syncope
 Lower cut-off rate: if a higher cut-off rate is used, a
hemodynamically significant VT will be missed, leading to
syncope or VF.
 But primary prevention indications were uncommon in the
past.

 Atrial arrhythmias (AF, atrial flutter, SVT)
 Oversensing due to lead fracture noise or overcounting (T-wave
oversensing, EMI, myopotentials)
Causes for inappropriate therapy (Shock or ATP)
Too aggressive treatment of VT than absolutely required
 Shock or ATP for premature detection of non-sustained VT;
premature ATP may accelerate NSVT
 Shock for sustained pace-terminable VT
Causes for unnecessary therapy (Shock or ATP)

 A randomized, single-blind, multicenter clinical study
 1500 patients with either ischaemic or nonischaemic disease with an
indication for a primary-prevention dual-chamber ICD or CRTD.
Patients with atrial fibrillation or device replacement excluded.
 Patients were assigned to one of three ICD programming groups with
the primary objective of finding their rate of a first occurrence of
inappropriate ATP or shocks.
Reduction in Inappropriate Therapy and
mortality through ICD Programming
(MADIT-RIT trial)
Moss A., etal. NEJM 2012; 367: 2275-83

 The ICD was not a new type of ICD.
 The programming choices were not new.
 Aim - To ignore the slower tachyarrhythmias in High-rate
and those of shorter duration in Duration-delay.

MADIT-RIT: Three Treatment Arms
Arm A
(Conventional)
Arm B
(High-rate)
Arm C
(Duration-delay)
Zone 1:
170 bpm, 2.5s delay
Onset/Stability Detection
Enhancements ON
ATP + Shock
Zone 1:
170 bpm
Monitor only
Zone 1:
170 bpm, 60s delay
Rhythm ID Detection
Enhancements ON
ATP + Shock
Zone 2:
Quick Convert ATP
Shock
Zone 2:
Quick Convert ATP
Shock
Zone 2:
Rhythm ID Detection
Enhancements ON
ATP + Shock
Zone 3:
Quick Convert ATP +
Shock

 During an average follow-up of 1.4 years, high-rate
therapy and delayed ICD therapy, as compared with
conventional device programming, associated with
- reduction in a first occurrence of inappropriate therapy
- reduction in all-cause mortality
- no significant difference in adverse events
e.g. syncope
 There was significant reduction by more than 70% of
inappropriate therapy in both high-rate and delayed
therapy groups
 Mortality was reduced by 55% in high-rate group
(p=0.01) and by 44% in the delayed-therapy group
(p=0.06).
MADIT-RIT Results

Lesson: Treat sustained tachyarrhythmias only. It does not favor
quick detection and therapy.
MADIT-RIT
Note that in MADIT-RIT:
•Primary prevention indication only
•Dual-chamber ICD and CRT-D only
•Excluded AF patients.

 A randomized, single-blind study to determine whether using 30
of 40 intervals to detect VT (long detection) reduces ATP and
Shock compared with 18 of 24 intervals (standard detection).
 Patients with
 Primary or secondary prevention,
 Single- or dual-chamber ICD or CRT-D
 Sinus or AF.
Effects of Long-detection Interval vs Standard-
detection Interval for ICDs on Antitachycardia
Pacing and Shock Delivery (ADVANCE III trial)
Gasparini M, et al. JAMA 2013; 309:1903-11

 After a median follow-up of 1 year, the long-detection group had
significantly less ICD therapies (ATP and shocks) and inappropriate
shocks.
There was significant reduction in all-cause hospitalizations.
No difference in arrhythmia syncope and mortality.
Lession: Broaden the long detection applicability to include
secondary prevention, single-chamber ICD and AF patients.
ADVANCE III trial Results

 A non-randomized trial with primary endpoint of the rate of
inappropriate shocks at one year post implant.
 A special detection algorithm includes wavelet morphology
analysis, discriminating T wave, assessment of lead integrity or
noise and improved recognition of nonsustained episodes.
 Patients with
 Single chamber ICD,
 Primary or secondary prevention,
 Sinus or AF.
Inappropriate shock rates in patients with
single chamber ICDs using a novel suite of
detection algorithms (PainFree SST study)
Meijer A, et al. Europace June 2013

 757 patients with single-chamber ICD
 97.6% of patients free of inappropriate shocks during the first
year post implant.
Lession: reducing inappropriate shock rate below 3% at 1 year is
possible
PainFree SST study Results

 A randomized study of primary prevention ICD (single or dual
chamber or CRTD) in 1670 patients.
 A combination of programmed parameters (higher detection
rates, longer detection intervals, empiric ATP, SVT discriminators)
vs conventional parameters.
 Result: Reduced ICD therapies without increasing arrhythmic
syncope and reduced all-cause mortality.
Programming ICDs in patients with primary
prevention indication to prolong time to first
shock (PROVIDE study)
Saeed M, et al. J Cardiovasc Electrophysiol 2014; 25(1): 52-59

 4896 patients from MADIT-RIT, ADVANCE 3, PROVIDE, RELEVANT.
 Reduced mortality by 23%
 Reduced inappropriate shocks and both appropriate and
inappropriate ATP significantly.
 64% risk reduction in primary endpoint (composite of death and
appropriate shocks) and 70% reduction in inappropriate shocks.
The impact of prolonged arrhythmia detection
times on outcomes: a meta-analysis
Scott PA, et al. Heart Rhythm 2014; D01: 10.1016. Abstract.
Buber J, et al. Europace 2014; 16(2): 227-234

1. ICD therapy has morbidity. The benefits of an ICD are greatly affected
by its programming.
2. Avoid inappropriate therapy and unnecessary therapy.
(less pain, less hospitalization, better QOL, improved survival)
3. To be certain that there is a sustained tachyarrhythmia before
treating the rhythm
 Prolonged duration of arrhythmia detection
 Faster rate of arrhythmia detection
 Use of ATP
 Algorithms for discrimination of SVT
Aims of ICD programming

• ICD is a medical breakthrough but has a complex functioning

• Adequate therapy prolongs survival but unnecessary therapy
increases morbidity and mortality

• Appropriate function requires adequate mechanical
components (Lead), electrical function (battery and
capacitor), software functioning (detection algorithms), and
substrate (appropriate DFT and safety margin)

• Appropriate function requires adequate mechanical
components (Lead), electrical function (battery and
capacitor), software functioning (detection algorithms), and
substrate (appropriate DFT and safety margin)
• Knowledge and know-how of all 4 components of ICD therapy
is essential for the caregiver

An ICD Prayer
O Creator,
Grant me the serenity to accept the things I should
not(cannot) change,
the voltage (courage) to change the things I can,
and the algorithm (wisdom) to know the difference.
Amen.

ICD troubleshooting

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