The Electrical Management of Cardiac Rhythm Disorders Tachycardia History of ICDs

1. The Electrical Management of Cardiac Rhythm DisordersTachycardiaHistory of ICDs The Electrical Management of Cardiac Rhythm Disorders, Tachycardia, Slide Presentation 08 History of ICDsThe Electrical Management of Cardiac Rhythm Disorders, Tachycardia, Slide Presentation 08 History of ICDs

2. The Genesis of ICDs The idea of the ICD came to Dr. Michel Mirowski when his friend died of SCD Concept: could a defibrillator be implanted in the body? Technological challenges Could an implantable device deliver sufficient energy? Could leads be developed to carry that much energy? How would the device detect arrhythmias? How could defibrillation become �automated�?

3. Dr. Michel Mirowski Dr. Harry Heller died of SCD in 1966 His friend, Dr. Michel Mirowski, knew that he might have lived had he received defibrillation immediately Technological and even ethical hurdles Was it ethical to even test such a device on humans? By 1969, Dr. Mirowski was working on the first experimental models of what would later become the ICD But it would be almost 20 years before the device was commercially available!

4. Time Line Sinai Hospital of Baltimore recruited Dr. Mirowski and offered him opportunity to work on ICD idea At Sinai, Mirowski teamed up with Martin Mower in the research lab In 1969, experimental model First transvenous defibrillation (1969) Canine implants (1970s) First human implant: 1980 (Johns Hopkins, Baltimore)

5. Technological Challenges Capacitor technology allowed small battery to store and deliver large amount of energy Transvenous defibrillation leads could carry defibrillation energy to the inside of the heart Circuitry could sense cardiac rhythms and interpret potentially dangerous ventricular tachyarrhythmias Device could be downsized enough to implant in the body

6. Early Devices 1980-1985 clinical trial of first ICDs 1985 FDA approved first ICD for human use Those first devices were 10 times the size of modern ICDs! Their large size mandated an abdominal implant Thoracotomy required to implant leads

7. Road to ICDs Point out that the time span from the first concept of the device (1966) to FDA approval (1985) was nearly 20 years!Point out that the time span from the first concept of the device (1966) to FDA approval (1985) was nearly 20 years!

8. ICD Evolution Cardioversion (lower-energy shocks) and �tiered therapy� Programmability (1988) First ICDs were custom-built since cutoff rates were set at the factory! Biphasic waveforms Multiple zones (VT/VF) Transvenous ICD leads Radically downsized generators (pectoral implants) Full-featured integrated pacemakers

9. Defibrillation Leads This image shows the Riata lead. Point out: First ICDs used epicardial leads which required a thoracotomy at implant Transvenous defibrillation leads like Riata provide pacing, sensing, and defibrillationThis image shows the Riata lead. Point out: First ICDs used epicardial leads which required a thoracotomy at implant Transvenous defibrillation leads like Riata provide pacing, sensing, and defibrillation

10. Single-Coil Defib Leads Pacing requires one or more electrodes on the lead to pace sense Shocking requires one or more �coils� on the lead to defibrillate A single-coil lead has one coil on the lead and forms the electrical circuit by using the ICD can as the other pole to complete the circuit

11. Modern Defibrillation Leads Integrated bipolar and true bipolar leads Refers to sensing cardiac signals Integrated bipolar uses distal shocking coil to sense cardiac signals True bipolar has dedicated distal sensing electrode Single-coil and dual-coil designs Very thin, comparable to some pacing leads! Choice of lead fixation mechanisms Active fixation (helix, corkscrew) Passive fixation (fins, tines) Steroid elution option

12. Progress: The Implant Procedure THEN Open-chest Took several hours General anesthesia Several days hospital stay Large device Abdominal implant No or very limited programmability NOW Minimally invasive implant Can take < 1 hour Conscious sedation May be done outpatient Devices ~ size of pacemaker Pectoral implant Extensive programmability

13. Progress: Device Functionality THEN Very few programmable options Short service life Only one therapy (defib) No pacing capability (if pacing was needed, a second device might be required) Could only be monitored in-clinic NOW Lots of programmability, including advanced features Four to six years service life Tiered therapy, even ATP Full pacing capability including some dual-chamber rate-responsive pacing with advanced features Remote patient monitoring

14. Device Acceptance The first ICDs were considered a device of last resort Patients had to be drug-refractory and survived at least two episodes of SCD Early concepts pitted drugs against devices as if they were mutually exclusive Devices became acceptable as first-line therapy for certain types of secondary-prevention patients Today, we know devices can provide additive benefits to drug therapy and that combination therapy (drugs plus devices) is ideal for most patients Recent studies have shown the mortality benefits of primary prevention therapy Point out: Not only have devices made tremendous progress in the past 20 years, so has our appreciation and acceptance of these devices. Originally, clinicians regarded ICDs as extreme therapy suitable for only the most challenging cases. Gradually, indications for ICD therapy expanded to include many patients with a documented history of potentially life-threatening ventricular arrhythmias. Around that time, the notion that devices somehow replaced drugs gave way to the prevailing view today of combination therapy (drugs plus devices). Recent clinical trials have demonstrated that patients at high risk of SCD (but without a history of ventricular tachyarrhythmias) derive mortality benefits from prophylactic ICD implantation. This introduced the concept of the primary-prevention patient.Point out: Not only have devices made tremendous progress in the past 20 years, so has our appreciation and acceptance of these devices. Originally, clinicians regarded ICDs as extreme therapy suitable for only the most challenging cases. Gradually, indications for ICD therapy expanded to include many patients with a documented history of potentially life-threatening ventricular arrhythmias. Around that time, the notion that devices somehow replaced drugs gave way to the prevailing view today of combination therapy (drugs plus devices). Recent clinical trials have demonstrated that patients at high risk of SCD (but without a history of ventricular tachyarrhythmias) derive mortality benefits from prophylactic ICD implantation. This introduced the concept of the primary-prevention patient.

15. The Future of ICDs Smaller, flatter devices (improved capacitor technology) Longer-lived devices (improved battery technology) CRT (addition of a third lead) Remote patient monitoring Wireless patient monitoring Special algorithms Expanded memory More automatic features Built-in monitors