Basics
Description
- An implantable cardiac device (ICD) is a small battery-powered electrical impulse generator implanted SC in patients at risk of cardiac arrest from cardiac arrhythmias.
- Lead(s) are positioned via venous return to heart and are endocardial (RA and RV) or epicardial (LV via coronary sinus).
- The device is able to detect and convert ventricular and atrial arrhythmias to sinus rhythm with electric shocks delivered between the ICD can and coil(s) in the RV (single coil) and the SVC/RA juncture (dual coil).
- Similar method of implantation as a pacemaker
- Newly released devices (S-ICD) no longer have endocardial leads reducing the risk of blood infection.
- 450,000 individuals experience sudden cardiac death yearly in US:
- >100,000 devices implanted in US each year
- ICDs have been shown to reduce mortality more effectively than antiarrhythmic drug therapy in patients with left ventricular dysfunction:
- Absolute risk reduction of mortality of 7% in the 1st 2 yr
- Benefit over antiarrhythmic drug therapy is limited to patients with ejection fractions of <35%
- Effective in reducing mortality in hypertrophic cardiomyopathy
- Both ischemic and nonischemic dilated cardiomyopathy patients show survival benefit with ICD
- Immediate postimplant complications:
- Pneumothorax
- Vascular perforation
- Acute lead dislodgement
- Appropriate shocks:
- 5% a year for primary prevention
- 20% a year for secondary prevention
- Electrical storm:
- ≥2 appropriate shocks delivered within a 24-hr period
- Inappropriate shocks:
- 10-20% of ICD recipients
- Oversensing
- Inappropriate classification of rapid supraventricular tachycardia
- Device infection:
- 1-12% of patients
- Acute 1-30 days-think staph
- Subacute >30 days-think Staphylococcus epidermidis or gram negatives
- 31-66% mortality if the device is left in place
- Infection may involve the skin, the generator, the defibrillation pocket, or the leads.
- Coagulase-negative staphylococci (42%)
- Methicillin-sensitive staphylococci (25%)
- MRSA (4%)
- Gram-negative bacilli (9%)
- Pocket hematoma do not aspirate
- Vascular occlusion
Etiology
- Electrical storm: (≥2 appropriate shocks delivered within a 24-hr period)
- Unknown
- Decompensated heart failure
- Acute ischemia
- Metabolic disturbances
- Drug proarrhythmia
- Thyrotoxicosis
- Fever with dilated cardiomyopathy
- Genetic channelopathies, Brugada syndrome, Long QT, catacholaminergic polymorphic VT, arrhythmogenic RV cardiomyopathy
- Postcardiac surgery
- ICD induced from left ventricular or T-wave pacing
- Inappropriate shocks:
- Oversensing:
- QRS, T-wave, P-wave, myopotential, electromagnetic interference (EMI)
- Frequent nonsustained ventricular dysrhythmias
- Lead fracture
- Loose setscrew
- Chatter between leads
- Header (device circuitry) problem
- Inappropriate classification of rapid supraventricular tachycardia:
- Atrial fibrillation
- Sinus tachycardia
- Atrial flutter
- Other supraventricular tachycardias (SVT)
- Device/site-related:
- Wound infection:
- Staphylococcus aureus (most aggressive and seen early)
- S. epidermidis (more indolent and later)
- Escherichia coli, Pseudomonas species, and Streptococcal species (less common)
- Pocket hematomas
- Vascular (venous thrombosis/embolism secondary to impedance of venous flow as a result of the ICD lead[s])
Diagnosis
Signs and Symptoms
- Felt bad before shock and good after: Likely appropriate therapy
- Felt good before and after shock: Likely inappropriate therapy
- Felt bad before and after shock: Consider ongoing arrhythmia or ischemia
- Appropriate shocks:
- Syncope or near syncope
- Lightheadedness or dizziness
- Shortness of breath
- Palpitations (non-SVT)
- Chest discomfort or pain
- Diaphoresis
- Inappropriate shocks:
- Palpitations (SVT)
- No symptoms (Lead-related fractures, inappropriate sensing)
- Device infection:
- Fever
- Chills
- Malaise
- Anorexia
- Nausea
- Diaphoresis
- Hypotension
- Heart murmur
- Wound infection:
- Pain
- Erythema
- Purulent drainage
- Warmth
- Fluctuance
- Skin erosion
- Hematoma at the insertion site (pocket hematoma):
- Vascular (thromboembolic phenomena):
- Unilateral swelling in upper extremity
- Superficial varicosities
History
- Therapy-related:
- Recent angina, heart failure
- Device-related:
- Recent implant (<14 days)
- Skin trauma to wound
- Lead-related:
- Repetitive arm motions
- "Twiddlers syndrome" (inadvertent manipulation of the device)
- Vascular:
- Recent implant
- Multiple leads
Physical Exam
- Vital signs
- Evidence of heart failure/acute coronary syndrome:
- Displaced point of maximal impulse
- Left ventricular heave
- Presence of an S3 or S4
- Presence of basilar rales
- Dullness to percussion
- Determination of jugular venous pressure
- Hepatojugular reflex
- Peripheral edema
- Device/site-related:
- Exam of wound/pocket:
- Demarcation of pocket (erythema)
- Purulent drainage
- Exam of affected upper extremity
Essential Workup
- Following ICD therapy:
- ICD interrogation will determine whether therapy was appropriate and can determine lead fracture if present.
- EKG (transient ST-segment changes and elevations of the cardiac enzymes may be seen after shock delivery and do not necessarily indicate myocardial damage)
- CXR may diagnose lead fracture.
- Device/site-related:
- Signs and symptoms of local vs. systemic infection
- Upper-extremity swelling suggests venous thrombosis.
Diagnosis Tests & Interpretation
Lab
- Therapy-related:
- 12-lead EKG
- Cardiac enzymes
- Device-related:
- CBC with differential
- Blood cultures
- Do not aspirate pocket
Imaging
- PA and lateral chest radiograph:
- Lead fractures
- Lead dislodgement
- Vascular US of upper extremity
- MRI absolutely contraindicated:
- Magnetic field may damage ICDs and cause heating at lead tip.
Diagnostic Procedures/Surgery
- Therapy-related:
- Device interrogation by electrophysiologist/cardiologist
- Application of magnet inhibits tachy therapies (does not affect brady support pacing).
- Device/site-related (pocket hematoma/infection):
- Referral to surgeon/electrophysiologist
- Electrocautery should generally be avoided in patients with ICDs unless device is deactivated with programming or with magnet application.
- External defibrillation is safe, but avoids shocking directly over ICD (see below).
Differential Diagnosis
- Appropriate therapies:
- Single shock following an episode of VT or VF with restoration of normal rhythm
- Inappropriate therapies:
- Usually due to SVT (afib), lead fracture, or EMI
- Phantom shocks:
- Patient awakened from sleep by a perceived shock(s)
Treatment
Pre-Hospital
Following an ICD electrical discharge:
- IV access
- Continuous EKG monitoring
- Advanced cardiac life support (ACLS) protocols
Initial Stabilization/Therapy
- ACLS protocols
- Magnet application inhibits ICD therapies.
- Device-related:
- Pain management
- Elevation of affected extremity (upper-extremity thrombosis)
Ed Treatment/Procedures
- Patients with devices should receive treatment according to standard ACLS protocols.
- Electrical storm may require IV antiarrhythmic agents such as amiodarone.
- Inappropriate therapies:
- Treatment of supraventricular dysrhythmia to prevent ICD shocks with β-blockers or calcium channel blockers
- Lead-related problems may require further surgical intervention or device reprogramming; magnet application will inhibit tachy therapies.
- Device infections:
- Broad-spectrum antibiotics
- Obtain blood cultures 1st
Medication
- Amiodarone 150 or 300 mg IVP followed by an infusion 1 mg/kg/h for 6 hr, then reduce to 0.5 mg/kg/h. Can rebolus (150 mg) as often as required
- Metoprolol: 5 mg IV as needed to control heart rate
- Diltiazem: 5-20 mg IV, then a maintenance drip to control heart rate
- Cefazolin: 1 g IV q8h
- Vancomycin: 1 g IV q12h
- Cephalexin: 500 mg PO QID
- Warfarin for documented venous occlusion, INR 2-3 for 3 mo
Follow-Up
Disposition
Admission Criteria
- Therapy-related:
- Ongoing/suspected cardiac ischemia or heart failure
- Multiple ICD shocks and initiation of antiarrhythmic agents for VF/VT or other SVT
- Treat underlying process and consult with electrophysiologist to determine if immediate interrogation is warranted.
- Device/site-related:
- Skin erosion
- Wound dehiscence
- Systemic infection/endocarditis
- Need for lead revision
- Expanding pocket hematoma
- Upper-extremity thrombosis
- Therapy-related:
- If patient is hemodynamically stable without evidence of active ischemia or heart failure, interrogation usually not required:
- Single-shock, appropriate therapy
- Consult with electrophysiologist and arrange appropriate follow-up.
- Device reprogrammed to avoid inappropriate therapy
- Device/site-related:
- Localized infection
- No signs of skin erosion
- Pocket not expanding:
- Prophylactic antibiotics are not indicated for pocket hematomas.
- Wound stable
Follow-Up Recommendations
- Therapy-related:
- Cardiologist or electrophysiologist
- Device-related:
- Surgeon or cardiologist/electrophysiologist
Pearls and Pitfalls
- Aspiration of device pocket is not recommended.
- Care should be taken not to deliver external shocks directly over the device, as it may shunt energy away from the heart.
Additional Reading
- Epstein AE, DiMarco JP, Ellenbogen KA, et al. 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2013;61(3):e6-e75.
- Kowalski M, Huizar JF, Kaszala K, et al. Problems with implantable cardiac device therapy. Cardiol Clin. 2008;26:441-458.
- Maron BJ, Spirito P, Shen WK, et al. Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy. JAMA. 2007;298:405-412.
- Scher DL. Troubleshooting pacemakers and implantable cardioverter-defibrillators. Curr Opin Cardiol. 2004;19(1):36-46.
Codes
ICD9
- V45.02 Automatic implantable cardiac defibrillator in situ
- V53.32 Fitting and adjustment of automatic implantable cardiac defibrillator
- 996.04 Mechanical complication of automatic implantable cardiac defibrillator
- 426.9 Conduction disorder, unspecified
- 427.31 Atrial fibrillation
- 427.32 Atrial flutter
- 427.3 Atrial fibrillation and flutter
- 427.89 Other specified cardiac dysrhythmias
ICD10
- T82.518A Breakdown (mechanical) of other cardiac and vascular devices and implants, initial encounter
- Z45.02 Encounter for adjustment and management of automatic implantable cardiac defibrillator
- Z95.810 Presence of automatic (implantable) cardiac defibrillator
- I45.9 Conduction disorder, unspecified
- I47.1 Supraventricular tachycardia
- I48.91 Unspecified atrial fibrillation
- I48.92 Unspecified atrial flutter
- I48.9 Unspecified atrial fibrillation and atrial flutter
SNOMED
- 441769002 Cardiac defibrillator in situ
- 431415002 Management of internal defibrillation (procedure)
- 234229000 Disorder of implanted cardiac defibrillator electrode (disorder)
- 44808001 conduction disorder of the heart (disorder)
- 49436004 Atrial fibrillation (disorder)
- 5370000 Atrial flutter (disorder)
- 6456007 Supraventricular tachycardia (disorder)