Implantable Defibrillator

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Contents 1 More Specific Terms 2 Introduction 3 Indications 4 Procedure 5 Complications 6 Management 7 Notes 8 More General Terms 9 Additional Terms 10 References

More Specific Terms

• automatic implantable cardioverter/defibrillator (AICD)

Introduction

• Implantable device to automatically detect & terminate ventricular tachycardia or ventricular fibrillation by delivering 1 or more shocks to the heart to terminate the arrhythmia.

Indications

• serious arrhythmias not controlled by medication*

• hemodynamically significant ventricular arrhythmia [2]

• risk of arrhythmia due to underlying heart disease#

• cardiomyopathy with LVEF <= 35%

• hereditary predisposition to fatal arrhythmias
  *The multicenter automatic defibrillator implantation trial ( MADIT) showed better survival in patients with inducible ventricular tachycardia with implanted defibrillators than those treated with anti-arrhythmic agents.
  #ICD may benefit patients with history of myocardial infarction & low LV ejection fractions (< 30-35%). [3,5];

• no survival benefit for patients with severe LV dysfunction [11]
• may benefit younger patients (HR=0.65) but not older patients [11]
• placement should be delayed until 40 days post- MI [2]
  
• Life expectancy should be > 1 year
• May be covered by Medicare [5]

Procedure

• these devices may be installed without thoracotomy
• some devices have back-up bradycardia & anti- tachycardia pacing
• devices are installed in the cardiac catherization laboratory
• after electrode placement & testing, a small generator (circuitry, capacitor, battery) is place under the skin in the chest
• the device records when arrhythmias occur & shocks are delivered
• battery life of 3-5 years
• shocks may occur during sinus rhythm or atrial fibrillation
• overall 1 year survival 90%

Complications

• infection

• originate in subcutaneous pocket created for generator box
• etiologic agents

• coagulase-negative Staphylococcus
• Staphylococcus aureus

• management:

• removal of the generator box
• systemic antibiotics for 2 weeks
• epicardial & transvenous wires

• should also be removed if possible
• if not, 6 weeks of antibiotic therapy

• device malfunction [6,8]

• inappropriate shocks increase mortality [9]
• women have fewer appropriate shocks and more lead complications [16]

• electromagnetic interference

• avoid metal detection devices at airports, courthouses ...
• cell phones may be used, but it is prudent to keep cellphone on opposite side of body from ICD
• avoid magnets or strong magnetic fields, i.e. MRI is contraindicated

• failure to prevent sudden death

• reccurent myocardial infarction & cardiac rupture account for 50% of deaths after myocardial infarction [10]

Management

• monitoring needed
• amiodarone effectively blocks many ICD shocks [6]
• metal detectors (hand-held & gates) used at airports are "probably safe" for patients with cardia pacemakers or implantable cardioverter-defibrillators ( ICDs) [13,15]

Notes

• 20% of implantable cardioverter-defibrillators are placed contrary to evidence-based guidelines [12]
• implantable cardioverter-defibrillators ( ICDs) & cardiac resynchronization therapy ( CRT) devices often include a feature that measures intrathoracic impedance, potentially providing an early warning system for decompensation by detecting pulmonary fluid retention [14]

More General Terms

• cardiovascular implantable electronic device (CIED)
• defibrillator

Additional Terms

• cardiac device infection
• cardiac pacemaker
• cardiac resynchronization therapy (CRT)
• ICD driving guidelines
• multicenter automatic defibrillator implantation trial (MADIT)

References

1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 67, 68
2. Medical Knowledge Self Assessment Program (MKSAP) 11,15, American College of Physicians, Philadelphia 1998,2009
3. Journal Watch 22(9):67, 2002 Moss AJ et al, N Engl J Med 346:877, 2002
4. Journal Watch 25(5):37-38, 2005 Hohnloser SH, Kuck KH, Dorian P, Roberts RS, Hampton JR, Hatala R, Fain E, Gent M, Connolly SJ; DINAMIT Investigators. Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction. N Engl J Med. 2004 Dec 9;351(24):2481-8. PMID: [1]
   - Bardy GH, Lee KL, Mark DB, Poole JE, Packer DL, Boineau R, Domanski M, Troutman C, Anderson J, Johnson G, McNulty SE, Clapp-Channing N, Davidson-Ray LD, Fraulo ES, Fishbein DP, Luceri RM, Ip JH; Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) Investigators. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med. 2005 Jan 20;352(3):225-37. PMID: [2]
   - McClellan MB, Tunis SR. Medicare coverage of ICDs. N Engl J Med. 2005 Jan 20;352(3):222-4. No abstract available. <PubMed> PMID: [3] <Internet> [4]
   - Kadish A. Prophylactic defibrillator implantation--toward an evidence-based approach. N Engl J Med. 2005 Jan 20;352(3):285-7. No abstract available. PMID: [5]
5. Connolly SJ, Dorian P, Roberts RS, Gent M, Bailin S, Fain ES, Thorpe K, Champagne J, Talajic M, Coutu B, Gronefeld GC, Hohnloser SH; Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients (OPTIC) Investigators. Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC Study: a randomized trial. JAMA. 2006 Jan 11;295(2):165-71. PMID: [6]
   - Page RL. Antiarrhythmic drugs for all patients with an ICD? JAMA. 2006 Jan 11;295(2):211-3. No abstract available. PMID: [7]
6. Amin MS, Matchar DB, Wood MA, Ellenbogen KA. Management of recalled pacemakers and implantable cardioverter- defibrillators: a decision analysis model. JAMA. 2006 Jul 26;296(4):412-20. PMID: [8]
7. Torpy JM, Implantable Cardioverter-Defibrillators JAMA 2007, 297:1946
   - Zimetbaum PJ A 59-year-old man considering implantation of a cardiac defibrillator JAMA 2007, 297:1946 PMID: [9]
8. FDA MedWatch Oct 16, 2007 Medtronic Sprint Fidelis Defibrillator Leads [10]
9. Daubert JP, Zareba W, Cannom DS, McNitt S, Rosero SZ, et al; MADIT II Investigators. Inappropriate implantable cardioverter-defibrillator shocks in MADIT II: frequency, mechanisms, predictors, and survival impact. J Am Coll Cardiol. 2008 Apr 8;51(14):1357-65. PMID: [11]
   - Raitt MH. Implantable cardioverter-defibrillator shocks: a double-edged sword? J Am Coll Cardiol. 2008 Apr 8;51(14):1366-8. PMID: [12]
10. Pouleur A-C et al. Pathogenesis of sudden unexpected death in a clinical trial of patients with myocardial infarction and left ventricular dysfunction, heart failure, or both. Circulation 2010 Aug; 122:597. PMID: [13]
11. Physician's First Watch, Nov 2, 2010 Massachessetts Medical Society [14] Santangeli P et al, Meta-analysis: Age and Effectiveness of Prophylactic Implantable Cardioverter-Defibrillators Annals of Internal Medicine 2010, 153:592-599 <PubMed> PMID: [15] <Internet> [16]
12. Al-Khatib SM et al. Non-evidence-based ICD implantations in the United States. JAMA 2011 Jan 5; 305:43. <PubMed> PMID: [17] <Internet> [18]
    - Kadish A and Goldberger J. Selecting patients for ICD implantation: Are clinicians choosing appropriately? JAMA 2011 Jan 5; 305:91. PMID: [19]
13. Kolb CK et al. Do airport metal detectors interfere with implantable pacemakers or cardioverter-defibrillators? J Am Coll Cardiol 2003 Jun 4; 41:2054-9. PMID: [20]
    - Jilek C et al Safety of Screening Procedures With Hand-Held Metal Detectors Among Patients With Implanted Cardiac Rhythm Devices A Cross-sectional Analysis Annals of Internal Medicine November 1, 2011. 155(9):587-592 [21]
14. Journal Watch Massachussetts Medical Society Journal Watch Cardiology November 30, 2011 [22]
15. Jilek C et al Safety of screening procedures with hand-held metal detectors among patients with implanted cardiac rhythm devices: A cross-sectional analysis. Ann Intern Med 2011 Nov 1; 155:587 PMID: [23]
16. MacFadden DR et al. Sex differences in implantable cardioverter-defibrillator outcomes: Findings from a prospective defibrillator database. Ann Intern Med 2012 Feb 7; 156:195.
17. National Guideline Clearinghouse ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices). ngc-guideline: [24] PMID: [25]
    - Practice advisory for the perioperative management of patients with cardiac implantable electronic devices: pacemakers and implantable cardioverter-defibrillators. An updated report by the American Society of Anesthesiologists Task Force on Perioperative Management of Patients with Cardiac Implantable Electronic Devices. ngc-guideline: [26]

implantable cardioverter defibrillator (ICD)