Internal Cardiac Defibrillator

Aka: Internal Cardiac Defibrillator, Automatic Internal Cardiac Defibrillator, Implantable Defibrillator

1. See Also
   1. Pacemaker
   2. Cardiac Resynchronization Implantable Device
   3. Left Ventricular Assist Device (LVAD)
   4. Sudden Cardiac Death
2. Background: Device
   1. Device discharges current when triggered by life-threatening arrhythmia
   2. Pacemaker-like device with high capacity battery and capacitor
      1. ICD Lead in the right ventricular apex
      2. Defibrillator coils in right ventricle and superior vena cava
      3. Left ventricular pacing lead at the coronary sinus (biventricular ICD or resynchronization devices)
   3. Implantation procedure
      1. Device placed in upper left chest below clavicle
      2. Transvenous threading of leads
      3. Defibrillator is tested during implantation by triggering arrhythmia
      4. Placement in 1-2 hours by electrophysiology, cardiology, or cardiothoracic surgery
      5. Major complications: 1.5%
         1. Hematoma
         2. Displaced lead
         3. Pneumothorax
3. Precautions
   1. Optimal medical therapy is critical
      1. See Congestive Heart Failure
4. Indications: Primary prevention for Cardiomyopathy
   1. Ischemic Cardiomyopathy
      1. NYHA Class I: Ejection Fraction <30%
      2. NYHA Class II: Ejection Fraction <35%
   2. Non-ischemic Dilated Cardiomyopathy
      1. NYHA Class I: Ejection Fraction <35% (consider)
      2. NYHA Class II-III: Ejection Fraction <35%
5. Indications: Secondary Prevention
   1. Structural heart disease and history of Ventricular Tachycardia
   2. Cardiac Arrest survivor
      1. Ventricular Fibrillation
      2. Unstable Ventricular Tachycardia
   3. Brugada Syndrome
6. Contraindications
   1. Last revascularization procedure within 3 months
   2. Last Myocardial Infarction within 40 days
   3. Life expectancy <1 year
   4. Arrhythmia otherwise treatable with catheter ablation or other procedure (e.g. WPW)
7. Management: Patient has received shock with device
   1. Indications for immediate evaluation
      1. More than one shock delivered
      2. Cardiovascular (e.g. Chest Pain) or other systemic symptoms immediately preceded the shock
      3. Syncope
   2. Disposition
      1. Immediate emergency department evaluation for indications as listed above
      2. Routine cardiology clinic follow-up in 24 hours is sufficient if no emergent indications
   3. Evaluation
      1. Interrogate device
         1. Identify triggering rhythm (e.g. Ventricular Tachycardia)
         2. Identify rhythms for which shock would be inappropriate
            1. Sinus Tachycardia
            2. Atrial Fibrillation with rapid ventricular rate
      2. Diagnostics
         1. Electrocardiogram
         2. Troponin
         3. Seum electrolytes
   4. References
      1. Jones and Orman in Majoewsky (2012) EM:Rap 12(5): 4-6
8. Management: Turning off device
   1. Indications
      1. Emergency surgery
         1. Consult with electrophysiology if adequate time
      2. Palliative Care
         1. Device may repeatedly apply shocks at end-of-life (before device can be formally turned off)
   2. Device deactivated by applying a large magnet (typically doughnut shaped) over the device
      1. Device will only be disabled as long as magnet is over the device
      2. Consider taping magnet in place
   3. Device reactivated by removing magnet
      1. Device will reactivate within 10 seconds
9. References
   1. Myerburg (2008) N Engl J Med 359(21): 2245-53
   2. Stevenson (2006) J Card Fail 12(6): 407-12
   3. Turakhia (2010) Am Fam Physician 82(11): 1357-66