Automatic Internal Cardiac Defibrillator


Article Author:
Arshad Muhammad Iqbal


Article Editor:
Syed Jamal


Editors In Chief:
Shane Havens
Jim Wang
Koushik Tripathy


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Kyle Blair
Trevor Nezwek
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Abbey Smiley
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Daniyal Ameen
Altif Muneeb
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes
Komal Shaheen
Sandeep Sekhon


Updated:
9/9/2019 10:39:31 PM

Introduction

The automated internal cardiac defibrillator or shock box is the common name given to the Implantable Cardioverter Defibrillator (ICD).

ICD is a state of the art device that treats arrhythmias specifically those of ventricular origin like ventricular tachycardia and fibrillation. It has become the first line of defense in patients who are at high risk for sudden cardiac death (SCD) and has shown consistent survival benefit in cardiac arrest survivors (SCA), in patients with Heart failure and severe systolic dysfunction (left ventricular ejection fraction-LVEF less than or equal to 35%) as well as in patients with hypertrophic cardiomyopathy (HCM).[1][2]

ICD is essentially a pacemaker with the ability to recognize abnormally fast cardiac rhythm and provide immediate treatment which can be in the form of overdrive pacing called anti-tachycardia Pacing (ATP) or shock therapy which could be synchronized or asynchronized, depending on the recognized rhythm and the pre-programmed rhythm detection algorithm. It comes in three systems, a single lead or single chamber device, a dual lead or a dual chamber device and one that is coupled with cardiac resynchronisation therapy (CRT-D) that is essentially a bi-ventricular device with leads in right atrium (RA), Right ventricle (RV) and coronary sinus (CS) lead. Due to its proximity, CS lead is also called the LV lead.

In 2012, the US Food and Drug Administration (FDA) approved the sub-cutaneous device (S-ICD) which used sub-cutaneous leads rather than intra-cardiac leads. Recently, the wearable defibrillators (WCD) have also been introduced for short term usage.

Indications

Indications are usually secondary where the patient has already suffered and survived cardiac arrest due to ventricular fibrillation/ventricular tachycardia, or primary when the patient is at high risk of sudden cardiac death due to VF/ VT but has never had any such event.

Secondary prophylaxis usually involves event of cardiac arrest due to ventricular fibrillation (VF) or hemodynamically unstable, also known as pulseless, ventricular tachycardia (VT). Adequate workup and exclusion of reversible causes should be done first before deciding to put the device in, as is endorsed by the guidelines laid down by Heart Rhythm Society (HRS) and American College of Cardiology (ACC).[3]

Primary prophylaxis, as described above, involves implanting the device in patients who have not had sudden cardiac death due to VF or pulseless VT but are at high risk of having such an event. These have become the most common reasons for device implantation in recent times.

Class (I) recommendations for ICD implantation include[3]:

  • LV dysfunction with ejection fraction less than or equal to 35% and NYHA II/III symptoms
  • LV dysfunction with ejection fraction less than or equal to 35% due to previous Myocardial Infarction (MI) or at least 40 days post-MI and NYHA II/III symptoms
  • LV dysfunction with ejection fraction less than or equal to 30% due to previous Myocardial Infarction (MI) or at least 40 days post-MI
  • LV dysfunction with ejection fraction less than or equal to 40% due to previous Myocardial Infarction (MI) or at least 40 days post-MI and inducible VT/VF on EP study (EPS)
  • Syncope of unknown etiology and inducible VT/ VF on EPS
  • Sustained VT in the presence of structural heart disease

Contraindications

ICD is contraindicated in situations where there are reversible causes (like myocardial ischemia, sepsis, hypoxia, electrolyte imbalance, electrocution, etc.) leading to VT/VF.

Atrial arrhythmias with no concomitant VT/VF and incessant VT/VF are also contra-indications for ICD.

Equipment

ICD system consists of three components;

  1. The pulse generator or generator is the ovoid/circular pod that houses the sophisticated machinery which reads, recognizes and stores cardiac rhythm tracings as well as decides for the need and delivery of appropriate therapy (ATP or defibrillation) according to a pre-programmed algorithm. It is implanted in the sub-cutaneous pocket usually in the pectoral region. It also contains the battery and defibrillator which have finite charge and capacity to defibrillate and pace the heart, as the need be. This part also includes the manufacturer code which is readable on the magnified plain radiogram. The device programmer magnet is placed over Pulse-generator for purposes of magnet inhibition, interrogation, and external programming or therapy. Moreover, these generators also have wireless communication ability with compatible programmers, within a limited radius.
  2. Leads are the cables or silicone coated wires that connect the generator to the myocardium and house the electrodes which facilitate conduction between the device and myocardium. They remain inside the heart. They have screws at one end hooked to the device, and the cardiac end has either screws or tines by which the lead is secured in place inside the respective cardiac chamber.
  3. Shocking coil. Inside the ICD, the lead has a shocking coil which delivers the necessary charge for defibrillation/electrical cardioversion. ICD leads can be identified on plane radiograms by the presence of shocking coils which appear as localized and well demarcated spiral thickenings on the lead usually in the region of SVC on atrial lead and near the ventricular end of RV lead.

Personnel

The decision for ICD implantation rests with the patient's primary physician and usually requires referral to a cardiac electrophysiologist and rhythm device specialist for appropriate screening and procedural planning.

Preparation

Patients are required to undergo a whole body wash usually 24 hours before and should be kept NPO for at least 4 hours prior to the procedure.

Blood work-up consisting of platelet count and checking the INR  is run and addressed appropriately. HbA1c is also checked to ensure adequate glycemic control as this is essential for diabetic individuals to minimize the risk of infection.

In some cases, the implanting physician might also advice discontinuing anti-coagulants (warfarin, NOACs, DTIs, etc.) for a short period.

Technique

The patient is usually draped and prepped in a sterile manner similar to that for pacemakers with the pectoral region exposed, and the procedure is generally performed under local anesthesia along with conscious sedation.

The device is implanted in a sub-cutaneous pocket usually made in the pectoral region where the device generator is placed, the leads are then hooked to the generator at one end, and the other end of the lead is then advanced, via the subclavian vein, and positioned in the respective cardiac chamber. While there is no consensus regarding defibrillation threshold testing (DFT), some operators perform DFT after putting in the device to check for defibrillation thresholds and device optimization and then close the pocket after DFT.[4][5]

The procedure typically takes up to 90 minutes.

Although it is a daycare procedure, patients are usually retained over the night and are discharged the next day after device interrogation and obtaining a plain chest radiogram to check for lead placement.

Complications

Complications divide into short term and long term.

Short term complications (2 to 3%) are usually immediate and relate to the procedure; they are[6][7]:

  1. Access complications like bleeding, thrombosis of subclavian/ axillary vein and inadvertent puncture of lung tissue causing pneumothorax or hemothorax
  2. Pocket complications like pain, pocket hematoma and even Twiddler's syndrome which is the twisting and misplacement of the device, usually due to pressure exerted by expanding hematoma, that causes device malfunction usually by disrupting the lead and generator connections
  3. Device-related infection (1 to 2%), including endocarditis, have also been reported
  4. Serious complications (less than 1%) like pulseless electrical activity (PEA) and death can also occur during DFT

Long term complications (up to 4%) include[7][8]:

  1. Device-related pain
  2. Anxiety
  3. Lead fracture
  4. Inappropriate shock delivery
  5. Phantom shock (which means that the patient perceives as receiving shock therapy, but device interrogation doesn't reveal any such shock or event)
  6. Device erosion through the skin
  7. Device Infection - more so in cases of replacement or generator change, than new device implantation[8]
  8. Immunologic rejection - rare

Clinical Significance

ICDs have proven survival benefit. Since their inception in the late 1980s, they continue to improve in functionality and design and have provided a lifeline for high-risk patients who, can seek help in case of cardiac arrest, otherwise would not have made it to the hospital.

Patients with structural heart disease as well as cardiomyopathies, both ischemic and non-ischemic, fare equally from the device especially when its coupled with resynchronization therapy that provides not only mortality benefit but improves quality of life (QOL) and has also shown potential to aid in the recovery of LVEF.

Now, there is an ever-growing list of patients who can live up to their date of transplant with ICDs/CRT-Ds watching over them while they wait for the suitable donor.

Enhancing Healthcare Team Outcomes

With advances in cardiovascular healthcare and new strategies and therapies in the management of coronary heart disease and heart failure, the overall life expectancy of patients have increased and has led to an ever-growing population of patients with LV systolic dysfunction and an increased risk of sudden cardiac death. This has opened up avenues for device therapy not only to save but also to improve life.

The National Cardiovascular Data Registry (NCDR) also has setup device registry which helps physicians and hospitals to pool their data, share their experiences and help each other out which, not only, is translating into better outcomes for these patients but also re-assuring patients that there is hope, and there are health professionals for them, working for them.

There remains a taboo, a psychological component with these devices, the fear of not returning to their previous lives and the fear of getting shocked during treatment. However, this could be readily overcome by adequate support and proper patient counseling by the physicians, electrophysiologists, cardiac rehab staff, and the heart failure staff that are involved in the management of such patients.

Effective communication and timely referral are essential amongst physicians, cardiologists, electrophysiologists as well as rehab and cardiac staff and patient caretakers as these patients require a lot of medical and psychosocial support to return to and maintain an adequate quality of life.

All in all, these devices have become a valuable tool for the heart failure team.


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Automatic Internal Cardiac Defibrillator - Questions

Take a quiz of the questions on this article.

Take Quiz
What is the recommended management of an automatic implantable defibrillator in a patient undergoing major abdominal surgery?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is a contraindication for implantable cardioverter defibrillator implantation?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 56-year-old male was referred to the cardiology clinic for consultation. He had a 30-pack-year smoking history, coronary artery disease, hypertension, and past medical history of myocardial infarction ten years ago. Detailed medical history revealed that he feels comfortable as rest, but any ordinary activity, e.g., walking short distances (18-90 meters) causes dyspnea, ankle edema, palpitations, and chest pain. Echocardiography was done, which showed reduced left ventricular ejection fraction. The cardiologist advised the patient for the implantation of implantable cardioverter-defibrillator (ICD). Which one of the following is a class (I) indication for implantable cardioverter-defibrillator implantation?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 60-year-old male was referred to the cardiology clinic for consultation. He had a 30-pack-year smoking history, coronary artery disease, hypertension, and past medical history of myocardial infarction ten years ago. Detailed medical history revealed that he feels comfortable as rest, but any ordinary activity, e.g., walking short distances (18-90 meters) causes dyspnea, ankle edema, palpitations, and chest pain. Echocardiography was done, which showed reduced left ventricular ejection fraction. An implantable cardioverter-defibrillator was implanted. Now he presented to the emergency department with a complaint of feeling a jolt while walking, last night. He suspects that he has received a shock from his implantable cardioverter-defibrillator (ICD). What is the next best step in the management of this patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Automatic Internal Cardiac Defibrillator - References

References

A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias. The New England journal of medicine. 1997 Nov 27;     [PubMed]
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, Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. The New England journal of medicine. 2005 Jan 20;     [PubMed]
Epstein AE,DiMarco JP,Ellenbogen KA,Estes NA 3rd,Freedman RA,Gettes LS,Gillinov AM,Gregoratos G,Hammill SC,Hayes DL,Hlatky MA,Newby LK,Page RL,Schoenfeld MH,Silka MJ,Stevenson LW,Sweeney MO,Smith SC Jr,Jacobs AK,Adams CD,Anderson JL,Buller CE,Creager MA,Ettinger SM,Faxon DP,Halperin JL,Hiratzka LF,Hunt SA,Krumholz HM,Kushner FG,Lytle BW,Nishimura RA,Ornato JP,Page RL,Riegel B,Tarkington LG,Yancy CW, 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) developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. Journal of the American College of Cardiology. 2008 May 27;     [PubMed]
Brignole M,Occhetta E,Bongiorni MG,Proclemer A,Favale S,Iacopino S,Calò L,Vado A,Buja G,Mascioli G,Quartieri F,Tritto M,Parravicini U,Castro A,Tomasi C,Villani GQ,D'Acri MG,Klersy C,Gasparini M, Clinical evaluation of defibrillation testing in an unselected population of 2,120 consecutive patients undergoing first implantable cardioverter-defibrillator implant. Journal of the American College of Cardiology. 2012 Sep 11;     [PubMed]
Swerdlow CD, Reappraisal of implant testing of implantable cardioverter defibrillators. Journal of the American College of Cardiology. 2004 Jul 7;     [PubMed]
Klug D,Balde M,Pavin D,Hidden-Lucet F,Clementy J,Sadoul N,Rey JL,Lande G,Lazarus A,Victor J,Barnay C,Grandbastien B,Kacet S, Risk factors related to infections of implanted pacemakers and cardioverter-defibrillators: results of a large prospective study. Circulation. 2007 Sep 18;     [PubMed]
Uslan DZ,Gleva MJ,Warren DK,Mela T,Chung MK,Gottipaty V,Borge R,Dan D,Shinn T,Mitchell K,Holcomb RG,Poole JE, Cardiovascular implantable electronic device replacement infections and prevention: results from the REPLACE Registry. Pacing and clinical electrophysiology : PACE. 2012 Jan;     [PubMed]
Freeman JV,Wang Y,Curtis JP,Heidenreich PA,Hlatky MA, Physician procedure volume and complications of cardioverter-defibrillator implantation. Circulation. 2012 Jan 3;     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Surgery-Ophthalmology. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Surgery-Ophthalmology, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Surgery-Ophthalmology, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Surgery-Ophthalmology. When it is time for the Surgery-Ophthalmology board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Surgery-Ophthalmology.