ICD Evolution 1970 • Patent granted for first totally implantable defibrillator • System used an intracardiac catheter and SQ patch with detection via RV pressure transducerMichael Mirowski (1924-1990)
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)
The ICD System How it Works Atrium & VentricleVentricle • Bradycardia sensing• VT prevention • Bradycardia pacing• Antitachycardia pacing • Antitachycardia pacing• Cardioversion• Defibrillation
ICD How High Voltage Is CreatedBattery – Provides low voltage energy cTransformer – Multiplies Voltage cCapacitor – Stores high energy for use cHigh Voltage Shock – Delivered ondemand
ICD How High Voltage Is Created For Pacing Pacing Voltage Voltages Battery Multiplier 3.2 and Volts High High Energy Transformer Voltage ShocksFor Defibrillation Capacitor (Up to 800 Volts)
Battery & Charge Time Relationship Battery DOWN Both can Indicate Elective Replacement (ERI) Charge Time UP
Battery & Charge Time Relationship
Battery & Charge Time RelationshipBattery Voltage & Charge Time in an optimized ICD battery
The Importance of Charge Time 10 Seconds of VFThe longer the charge time, the longer this rhythm continues.
ComponentsICD Connector Blocks
Today’s Current® DR RF Header (6 set screws) New DF4 DR Header (2 set screws)23
COMPONENTSHigh Voltage Leads
High Voltage Leads EpicardialPlaced directly on the epicardium of the heart. Transvenous Introduced into the heart through a vein.
High Voltage Leads
High Voltage Leads Types of Transvenous LeadsTransvenous Passive Active No Fixation
Endocardial Lead Systems Passive Fixation (Tines)Active Fixation (Screw)
Transvenous Leads PlacementSingle Coil Dual Coil
Distal Coil Proximal Coil Connector Pins
High Voltage LeadsTypical Transvenous Lead
Transvenous Lead Steroid Tip*Steroid not available in all leads
Transvenous Lead Steroid TipBenefits of Steroid:• Reduces acute Trauma and Inflammation• Rapid Tissue Damage Repair• Reduced Fibrosis *Steroid not available in all leads
Transvenous Lead Lead Design Optimal Tissue Contact*Steroid not available in all leads
Lead Electrical Design Circuits• High Voltage Leads can have 2 Circuits: PACING & SENSING SHOCKING
Lead Electrical Design CircuitsPACING & SENSING Bipolar
Lead Electrical Design Pacing/Sensing Circuit • The electrical circuit for pacing and sensing includes: •Cathode – negative electrode (Tip) •Anode: positive electrode (Ring or Coil) BipolarConfiguration
Lead Electrical Design CircuitsPACING & SENSING Bipolar True vs. Integrated
Polarity Pacing/Sensing CircuitBipolaruses dedicated ring can as anodeIntegrated Bipolaruses RV Coil can as anode
Lead Electrical Design CircuitsPACING & SENSING Bipolar True vs. Integrated SHOCKING High Voltage Coils
Polarity Shocking CircuitSingle 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)
High Voltage Leads Connector Pins Pace / Sense Connection = IS-1 (International Standard)High Voltage Defibrillation Connections = DF-1 (Defibrillation Standard)
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)
Shocking Circuit VectorsExample: A > B(Active Can > RV HV Coil)
Shocking Circuit VectorsExample of Dual Coil: AX > B(Active Can + SVC HV Coil > RV HV Coil)
Sensing• Sensing - what the device “sees”• Electrical Activity - what thedevice is looking for• Lead – contains the ‘eyeball’ of the device
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
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)
SENSINGThe Intracardiac Electrogram EGM
Sensing• Sensing is: –The process of identifying cardiac depolarizations from an intracardiac electrogram
Sensing The EGM Signal• The signal from a depolarization wave passing between sensing electrodes Processed by Depolarization Wave Device
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)
The EGM Signal Amplitude• Measured Peak-to-Peak Typical Ventricular EGM • >5 mV for optimal sensing
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
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
The EGM Signal NearfieldEGM Source = Tip-to-Ring / Tip-to-Coil Tip-to-Ring Tip-to-Coil (Bipolar) (Integrated Bipolar)
The EGM Signal Nearfield Morphology Comparison SINUS RHYTHM VTEGM Source = Tip-to-Ring / Tip-to-Coil
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
The EGM Signal Farfield EGM Source = VariableCan-to-RV Coil RV Coil-to-SVC(HVA to HVB) Coil (HVB to HVX)
The EGM Signal FarfieldMorphology Comparison SINUS RHYTHM VTEGM Source = Variable
SENSINGThe Sensing Circuit
The Sensing Circuit• Upon being ‘seen,’ a signal is transported through the sensing circuit
The Sensing Circuit The Amplifier
The Sensing Circuit The Bandpass Filter
The Sensing Circuit Rectifier
The Sensing Circuit Level Detector
The Sensing Circuit Level Detector
The Sensing Circuit
The Sensing Circuit
Sensitivity• Minimum amplitude of electrical signal that registers as a sensed event – Set in Millivolts (mV) – Programmable Setting
Sensitivity ProgrammedIf set at .15 mV
Sensitivity ProgrammedIf set at .3 mV T-wave Not Sensed
Sensitivity Auto-Adjusting• Allows sensing of fine VF waves• Prevents sensing of T-waves, cross-chamber events, and pacing artifacts
Auto-Adjusting Sensitivity Decay Constant
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 VentricularSensed Refractory Sensed Refractory
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
Question?What are the consequences ofundersensing?• Failure to sense VF, therefore, no therapyinitiated• Failure to treat VT that can accelerate to VF• Can be fatal
Question?What are the consequences ofoversensing?• Inappropriate therapies• Potential for inducing fatal arrhythmias• Patient suffering due to inappropriatetherapy
Marker Channel™• Display: – Pace/Sense annotations – ICD functional annotations: • Sensing • Detection • Therapy • Other information * in Medtronic devices
ICD Automated Functions Detection
Question?What does “Detection” mean?A device defined arrhythmia is presentbased on what is sensed.
Detection• Confirms a sensed rhythm as an arrhythmia based on: – Rate – Duration
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
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
Detection Consecutive CounterUsed for detection of VT
Detection Probabilistic CounterNID =12/16
Detection Detect DurationNon-Sustained: Duration not met / No Detection Sustained: Duration met / Detection Occurs
Question?What if the fast, sustained ventricularrhythm is the result of an SVT?
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
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)
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
Classification: MD Morphology Discrimination Sinus Supra-Ventricular VentricularElectrical wavefronts generated by focus approach electrodes fromdifferent directions depending on the focus location.
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
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
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
SVT Discriminators Onset• Onset Percentage = 81% 530ms X 81% = 430ms ≠ 460ms = Onset 430ms Not Met * in Medtronic devices
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
SVT Discriminators StabilityStability = 50 ms Varies >50 ms from Unstable previous 3
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
Optimized DR Discriminators Bigeminal Avoidance Ventricular frequency > VT detection Compare atrial & ventricular frequency V<A V=A V>A SVT On Stability VTMorphology 40 ms Off 45% Morphology Onset 5 out of 8 AVA 45%, 5/8 Passive 80 ms ATU On Any
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)
PR Logic™ Pattern•Distinguishes SVTs by analyzing P and R-wave: – Pattern: number and position of atrial events relative to ventricular events
Question?What happens when a magnet isapplied over an ICD?
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
ICD Automated Functions Therapy
Question?Can you name some therapies deliveredby an ICD?
ICD Therapies• ICD Therapy – Low Power (Pacing Therapies) • Anti-tachycardia Pacing (ATP) • Bradyarrhythmia Pacing – High Power (Shock Therapies) • Cardioversion • Defibrillation
Anti-Tachycardia PacingRe-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
Anti-Tachycardia Pacing•Has programmable: – Sequences – the number of times ATP will be applied upon re-detection
Anti-Tachycardia Pacing•Has programmable: –Pulses – the number of pulses per sequence
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)
Anti-Tachycardia Pacing• Types:–Burst •A series of pacing pulses delivered at equal intervals •Interval decrement per sequence
Anti-Tachycardia Pacing Burst
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
Anti-Tachycardia Pacing Ramp
Anti-Tachycardia Pacing Burst and Ramp ComparisonProgrammed Values: Programmed Values: Number of S1 Pulses = 4 Number of S1 Pulses = 4 Number of Sequences = Number of Sequences = 44 R-S1% = 91% R- S1% = 91% Decrement* = 10 ms Decrement* = 10 ms * Decrement between pulses* Decrement between sequences * Adds a pulse per sequence
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
Cardioversion•Delivers shock on an R-wave•Aborts if synchronization cannot be obtained due to arrhythmia termination
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
Question?When does the device call a therapya success?
ICD Therapies Termination/Redetection•“8 to terminate” rule –8 sinus and/or paced beats outside the slowed programmed detection zone * in Medtronic devices
ICD System Troubleshooting
Troubleshooting Overview•ICD System Issues –Lead System & Connections –Device –Other Issues (Patient, EMI)
ICD SYSTEM ISSUESLead Systems & Connections
Question?In an ICD System, whatcomponent is generally known tobe the source of most issues? a. deviceb. lead
ICD System Issues Leads• Points of Failure – Acute (common suspects) • Connector • Lead Dislodgement/Perforation
ICD System Issues LeadsPoints 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)
ICD System IssuesPoints of Failure – Acute (common suspects) Connector What kinds of things can go wrong here?
ICD System Issues ConnectorCan you identify a problem? Set screw is obstructing the bore
ICD System Issues ConnectorWhat might happen if a lead is connected?
ICD System Issues ConnectorWhat is going on here? Set Screw Noise
ICD System Issues• Points of Failure – Acute (common suspects) • Connector Lead dislodgement/perforation How do we know when this occurs?
ICD System Issues Lead DislodgementCommon 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
ICD System Issues Lead DislodgementCan you identify the dislodged lead(s)?
ICD System Issues Lead Dislodgement• Avoiding dislodgements – Ensure sufficient slack in lead – Use suture sleeves – Check lead tip stability during implant
ICD System Issues Lead Perforation• Occurs when: – Lead tip exits the heart, through the heart
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
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)
ICD System IssuesCan you identify a problem? 1st Rib-Clavicle Crush (lead fracture)
ICD System Issues Lead Fracture Lead Crush1st Rib & Clavicle Crush
ICD System Issues Lead FractureCan you identify the fracture?
ICD System Issues Lead Fracture• Common behavior – Erratic sensing – Intermittent or loss of capture – High lead impedance
ICD System Issues Lead FractureExample
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)
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
ICD System Issues Insulation BreakExample
ICD SYSTEM ISSUES Device
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 DeviceCan you identify a problem? T-wave oversensing
ICD System IssuesCan you identify the problem? Device*Medtronic Programming Undersensing
ICD System Issues DeviceCan you identify the problem? Undersensing
Infection/Erosion/Allergy Allergy TestingAllergy Test Metals (included in kits) Allergy Test Kit Contents: Polyurethane Silicone Titanium Platinum Iridium Polysulfone Epoxy Gold-sputtered devices
Abandoned Leads• Chatter between active and abandoned leads may cause inappropriate therapy
Electromagnetic Interference (EMI)• The sensing of electrical signals other than those produced by the heart 60 Hz (oversensing)
Test Your SkillsWhat might you suspect from this EGM?
Case Study (Noise)• Male 62 years• ICD Implant for VT/VF• Patient got 11 shocks
Fast Path Summary
Trends: Signal Amplitude
Trends: Lead Impedance Impedance Decrease
Appropriate or Inappropriate Therapy?
Episode 52A/V lead 皆有noise
Case study (Morphology Change)• Female 72 years old• ICD for VT episodes• Standard follow-up patient didn’t feel anything.
Episode 1: Appropriate or Inappropriate Therapy? Morphology score low
MD Auto UpdateMorphology auto update score increase to 100
Episode 3: Correct Diagnosis? SVT Diagnosis
DiagnosticsAfter morphology update Correct Discreamation is SVT
Indications for ICD Therapy
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 ofsurvival with good functional capacity for more than 1 year.
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 ofsurvival with good functional capacity for more than 1 year.
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 ofsurvival 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.
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 ofsurvival with good functional capacity for more than 1 year.
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 ofsurvival with good functional capacity for more than 1 year.
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 ofsurvival with good functional capacity for more than 1 year.
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 ofsurvival with good functional capacity for more than 1 year.
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 ofsurvival with good functional capacity for more than 1 year.
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 ofsurvival with good functional capacity for more than 1 year.
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-averagedelectrocardiogram.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.
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.
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.
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.
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.
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.
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.
Notable Changes in 2008 ACC/AHA/HRS Guidelines1. 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.