ICD troubleshooting

Satyam Rajvanshi

ICD System Troubleshooting

Word meaning

• ICD

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 1966Dr Mirowski

ICD: Conception 1966Over-the-counter electronic components

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

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

Evolution of ICD Therapy

Word meaning

• Troubleshooting

Word meaning

• Troubleshooting

Word meaning

• Troubleshooting

ICD FUNCTIONNG

Sensing Detection Therapy

ICD treats ventricular tachyarrhythmias

SENSING IN ICD

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

ICD sensing and EGMs

Sensing auto-adjust

Beat-to-beat auto-adjusting sensitivity

Sensing auto-adjust

Beat-to-beat auto-adjusting sensitivity

Sensing auto-adjust

Sinus rhythm – To avoid oversensing T wavesVF – To avoid undersensing

Sensing auto-adjust

Sensing auto-adjust

DetectionAlgorithm 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 discriminatorsProgrammable 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 ReconfirmationBrief 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

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

Detection

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 programmedPrevious average onset percentagei.e. onset is “sudden” in VT


Onset percentage: 81%




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

Boston scientific: RHYTHM ID

St Jude: Rate Branch

Biotronik: SMART

Medtronik: PR Logic

ICD TROUBLESHOOTING

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 depletionPremature battery depletion• Latest iterations of ICDs claim battery lifespan of more than 10 yrs

with 2 shocks per year and upto 40% pacing support


with 2 shocks per year and upto 40% pacing support• Causes related to pacing– Unnecessary ventricular pacing– High pacing outputs– Lead insulation failure


with 2 shocks per year and upto 40% pacing support• 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 problemsEvaluation in all patients usually• Electrograms from all electrodes on the lead

– Sensed amplitude (P/R)– Any oversensing

Lead problemsEvaluation in all patients usually• Electrograms from all electrodes on the lead• Pacing threshold, pacing impedance

– Impedance varies with manufacturer/lead type– 200-2000 ohms

Lead problemsEvaluation in all patients usually• Electrograms from all electrodes on the lead• Pacing threshold, pacing impedance• Painless high voltage electrode impedance

– 25-75 ohms– Review of periodic assessment

Lead problemsEvaluation in all patients usually• Electrograms from all electrodes on the lead• Pacing threshold, pacing impedance• 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

TROUBLESHOOTING AN ICD SHOCK

Evaluate ICD shock

Evaluate ICD shock

Inappropriate Shock

Tachycardia

Absent(Oversensing)

IntracardiacT/P wave

Double count

ExtracardiacEMI

Myopotentials

Present(Inappropriate SVT detection)

Extracardiac oversensing

Extracardiac oversensing

Intracardiac Oversensing

Lead failure

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

EGM to differentiate SVT/VT• 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

EGM to differentiate SVT/VT• 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’

Multiple shocks / VT storm

Multiple shocks / VT storm

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

PERIOPERATIVE MANAGEMENT

Perioperative management

PROGRAMMING ICD

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 ArmsArm A(Conventional)

Arm B(High-rate)

Arm C(Duration-delay)

Zone 1:³170 bpm, 2.5s delayOnset/Stability Detection Enhancements ONATP + Shock

Zone 1:170 bpmMonitor only

Zone 1:³170 bpm, 60s delayRhythm ID Detection Enhancements ONATP + Shock

Zone 2:³200 bpm, 1s delayQuick Convert ATP Shock

Zone 2:³200 bpm, 2.5s delayQuick Convert ATP Shock

Zone 2:³200 bpm, 12s delayRhythm ID Detection Enhancements ONATP + Shock

Zone 3:³250 bpm, 2.5s delayQuick 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

CONCLUSION

• 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

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.

Health & Medicine

ICD troubleshooting