ICD: Basics, Programming and Trouble-shooting Amir AbdelWahab, MD Electrophysiology and Pacing Service Cardiology Department Cairo University Feb 2013
Evolution of ICD Technology ICD Evolution
Indications for ICD (ACC 2008) 1. Cardiac Arrest Due to VT or VF Not due to transient or reversible cause Class I 2. Spontaneous sustained VT With structural heart disease 3. Syncope of undetermined origin with: Inducible sustained VT or VF that has clinical relevance and/or hemodynamic significance
4. Primary prevention of SCD: Indications for ICD ICM (LVEF < 35% due to prior MI) 40 days post-mi and NYHA FC II or III (LVEF < 30% with NYHA FC I) NICM (LVEF 35) and NYHA FC II or III Class I 5. Nonsustained VT with: Prior MI, LVEF < 40%, Inducible VF or sustained VT (Non-suppressible by antiarrhythmic drugs)
Indications for ICD 1. Sustained VT Normal or near-normal LVEF Class IIa 2. Unexplained Syncope with: Significant LV dysfunction and NICM
The ICD System ICD System = + +
Device Components ICD
Battery Depletion ICD
Charge Time The time between arrhythmia detection and therapy delivery Initiated upon the detection of an arrhythmia Time depends on device model and battery integrity
Battery & Charge Time Relationship Battery Voltage & Charge Time in a typical ICD Battery
Connector Block ICD
Typical Transvenous Lead High Voltage Leads
High Voltage Leads
Pacing/Sensing Circuit Polarity
Shocking Circuit Polarity 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)
Vectors Shocking Circuit
ICD Functions and Programming
ICD Functions Sensing The EGM Signal The Sensing Circuit Marker Channels Detection Suspension (Magnet) Rate & Duration (NID) Detection Zones SVT Discrimination Single Chamber Dual Chamber Redetection Therapy Tachyarrhythmia Anti-tachycardia Pacing (ATP) Cardioversion (Non-committed) Defibrillation (Committed) Bradyarrhythmia Pacing Modes Parameters Other Brady Therapies Low Power Low Power
Sensing ICD Functions
The EGM Signal Nearfield Electrodes are close in range EGM Source = Tip-to-Ring / Tip-to-Coil Narrow signal less myocardium in range Used for arrhythmia detection Fields Farfield Electrodes are further in range EGM Source = Variable More myocardium covered in range Can resemble surface EKG
True vs. Integrated Bipolar Sensing Range of eyeball is determined by polarity True Bipolar Sensing Integrated Bipolar Sensing Tip-to-ring Smaller surface area More localized sensing Tip-to-coil Larger surface area Broader sensing area
Sensing The EGM Signal A signal from inside the heart vs. surface
Morphology Comparison The EGM Signal Nearfield SINUS RHYTHM VT EGM Source = Tip-to-Ring / Tip-to-Coil
The EGM Signal EGM Source = Variable Farfield Can-to-RV Coil (HVA to HVB) RV Coil-to-SVC Coil (HVB to HVX)
Morphology Comparison The EGM Signal Farfield SINUS RHYTHM VT EGM Source = Variable
Sensing Marker Channel Marker Channels identify what the device sees, and does at all times on a beat-to-beat basis:
ICD Automated Functions - Detection Confirms a sensed rhythm as an arrhythmia based on: Rate Duration
Measured in: Detection Beat-to-beat intervals (milliseconds), or Beats-per-minute (BPM) Detection Rate 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
Measured in: Detection 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 Detect Duration
Detection Consecutive Counter Used for detection of VT
Detection Probabilistic Counter NID = 12/16
Detection Classify tachyarrhythmias based on cycle length (rate) Detection zones: VT = Ventricular Tachycardia FVT = Fast Ventricular Tachycardia VF = Ventricular Fibrillation Programmable (in milliseconds)
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
Discriminate based on: SVT Discriminators 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)
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 RHYTHM VT
Stability = 50 ms SVT Discriminators Stability Varies >50 ms from previous 3 Unstable * in Medtronic devices
ICD Therapy Low Power (Pacing Therapies) Anti-tachycardia Pacing (ATP) Bradyarrhythmia Pacing High Power (Shock Therapies) Cardioversion Defibrillation ICD Therapies
Tachyarrhythmia Therapy Anti-Tachycardia Pacing (ATP) ICD Therapies Pacing pulses delivered at a rate faster than the rhythm detected Can successfully terminate re-entrant tachycardias Low Power
Has programmable: Anti-Tachycardia Pacing Sequences the number of times ATP will be applied upon re-detection
Has programmable: Anti-Tachycardia Pacing Sequences the number of times ATP will be applied upon re-detection Pulses the number of pulses per sequence
Has programmable: Anti-Tachycardia Pacing 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)
Anti-Tachycardia Pacing Types: Burst A series of pacing pulses delivered at equal intervals Interval decrement per sequence
Anti-Tachycardia Pacing Burst
Types: Anti-Tachycardia Pacing 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
Anti-Tachycardia Pacing Ramp
ICD Therapies Anti-Tachycardia Pacing (ATP) Pacing pulses delivered at a rate faster than the rhythm detected Can successfully terminate re-entrant tachycardias Cardioversion (CV) High Power Low 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
Cardioversion Programming
Defibrillation Programming *Medtronic Programming Screen
ICD Therapies Shock delivery waveform Biphasic waveforms generally provide: Lower defibrillation thresholds Higher implant success rates Reduced short-term myocardial injury Faster return to sinus rhythm post-shock
ICD Trouble-shooting
ICD SYSTEM ISSUES Lead Systems & Connections
ICD System Issues Leads Points of Failure Acute (common suspects) Connector Lead Dislodgement/Perforation
ICD System Issues 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) Leads
Avoiding dislodgements Ensure sufficient slack in lead Use suture sleeves Check lead tip stability during implant ICD System Issues Lead Dislodgement
ICD System Issues Lead Fracture Example
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 ICD System Issues Device
ATP caused Acceleration ICD System Issues Device: Inappropriate Programming Can you identify a problem?
ICD System Issues Device T-wave oversensing
ICD System Issues Device Double Counting
ICD System Issues Device Undersensing
Magnet Interactions A Magnet over an ICD May prompt tones from the ICD (varies by manufacturer) Has no effect on pacing Temporarily suspends detection/therapy Function resumes upon removal of magnet
Recorded Episodes EGM Strip An electrogram of a detected arrhythmia. *Medtronic Programming Screen
4-Step Troubleshooting Strategy Step 1: Define the Problem Patient Information Diagnostic Retrieval Step 2: List the Potential Causes Lead Issues Device Issues Other Issues Step 3: Determine the Cause(s) Diagnostic Testing & Analysis Step 4: Correct the Problem Non-Invasive vs. Invasive
4-Step Troubleshooting Strategy The more puzzle pieces we can assemble, the easier it will be to see the answer..
Test Your Skills What could be happening here? Next Steps?
What is happening here? Test Your Skills
Thank You!