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What is an implantable cardioverter defibrillator?

The implantable cardioverter-defibrillator is an astonishing device that has splendid capabilities to automatically monitor, diagnose, and help regulate the normal heart rhythm. It is a small electronic device connected to the human heart to increase its heart rate and manage life-threatening electrical problems in the heart.

The early version of the implantable cardioverter-defibrillator came into clinical practice in 1930. The machine used these days is the exclusive version of the previous ICD. The original device only diagnosed ventricular fibrillation, but the new version also monitors, detects, and treats ventricular tachycardia. The advanced features of implantable cardioverter-defibrillator have helped save countless patients from life-threatening electrical problems of the heart.

ICD implantation:

The latest versions of ICDs are about the size of a stopwatch and are implanted under the skin under the collarbone. It is constructed of a pulse generator and wires known as leads. The pulse generator is made up of a mini-computer and a battery. One or more lead wires are used to connect the pulse generator with the specific locations of the heart.

What is Ventricular Fibrillation

ICDs are designed to monitor and if needed, shock the heart back into a normal rhythm. If the heart’s rhythm goes abnormally fast, it paces its lower chamber and promotes its normal rhythm. It can also perform defibrillation (electric shock) on the heart to reset its rhythm and avoid sudden cardiac death. Another amazing feature of an ICD is that it stores and records information about your heart rhythm and the therapies performed by ICD. It helps the doctors in reviewing the health condition of the heart rhythm.

People with an ICD implantation often can’t feel anything different when ICD paces the heart. But defibrillation is often felt by the patients as a sudden ” kick in the chest” due to sudden electric shock given to the heart.

Another characteristic of ICD is that it can be programmed to act as a “pacemaker.” A pacemaker is also a small electric device for treating cardiac problems. It sends small pulses to the heart to maintain a steady heartbeat. If the heart rate becomes too slow after an electric shock or after defibrillation an ICD has a backup pacemaker, which sends small pulses as signals to the heart and brings the heartbeat back to a normal rhythm. The backup pacemaker of the ICD keeps working until a normal rhythm of the heart is achieved. An ICD automatically becomes a pacemaker at any instant when the heart rate decreases after a reset or electric shock (defibrillation).

In some cases, when patients don’t require the ‘backup’ pacemaker or ATP, the ICD device uses Subcutaneous Implantable Defibrillator (S-ICD). This state sends high-energy electric shocks to the heart through leads wires, avoiding the potential risks. Lead wires carry the electric shock through the veins into the heart. ICD or cardiovascular medicine is the primary prevention for patients surviving cardiac arrest. Secondary prevention is proper medication.

Why might you need an implantable cardioverter-defibrillator?

ICD implantation depends upon the person’s cardiac conditions. Suppose a person has suffered from sudden cardiac arrest due to ventricular fibrillation or has suffered from ventricular tachycardia or has other inherited heart problems. In that case, his medical practitioner may recommend an ICD.

Implantable cardioverter-defibrillators are frequently implanted in people who have a high probability of sudden cardiac death due to ventricular arrhythmia. This consists of patients with congestive heart failure, having issues with blood pumping (such as abnormal left ventricular ejection fraction). Patients who have a history of hemodynamically significant sustained VT, heart failure, or atrial fibrillation are typical candidates for an ICD.

What is Ventricular Fibrillation?

Another dangerous type of arrhythmia is Ventricular fibrillation, which is an irregular heart rhythm. Ventricular fibrillation (V-Fib) directly affects the heart’s ventricles, as described in its name. The human heart is made up of four chambers. Each chamber has its job. The two lower or bottom chambers are known as ventricles.

What is Ventricular Fibrillation

In healthy conditions, the human heart pumps blood through these chambers forcing blood circulation throughout the body. V-Fib is known as “ventricular fibrillation” because it begins from ventricles. When the Sinoatrial Node (SA Node) sends wrong electric signals that instruct the heart to fibrillate instead of pumping blood, it causes abnormal heart rate. The fibrillation or quivering of the heart leads to no pumping of blood throughout your body. If ventricular fibrillation occurs several times, then it is known as an “electrical storm.”

Treatment: ICD (implantable cardioverter-defibrillator) insertion or antiarrhythmic drug therapy

Risk elements for ventricular fibrillation:

Ventricular fibrillation could be triggered due to the following:

  • cardiomyopathy (weakness of heart muscle)
  • an acute or prior myocardial infarction (heart attack)
  • genetic or inherited diseases like Brugada disease, or hypertrophic cardiomyopathy, long or short Q.T. syndrome
  • reaction to medications
  • congestive heart failure
  • ischemic cardiomyopathy
  • abnormalities in the electrical activity or electrolytes

What is Ventricular Tachycardia?

Ventricular tachycardia is another dangerous arrhythmia that is due to an abnormally fast heart rate. This disorder also occurs in the lower chambers, “Ventricles” of the heart. That’s why these are known as “ventricular tachycardia.” For instance, three or more beats in a row or 100 beats per minute are considered ventricular tachycardia. If the situation continues for more than three seconds in a row, it may trigger other dangerous cardiac disorders. When arrhythmia or the above-described situation lasts for more than 30 seconds, it is called sustained ventricular tachycardia. Sustained ventricular tachycardia doesn’t give the heart enough time to fill with blood before the heart contracts again. This will have negative effects on the flow of blood through your body.

Treatment: Implantable cardioverter-defibrillator implantation or antiarrhythmic drug therapy

Causes of Ventricular tachycardia:

Sometimes the causes of V.T. can be discovered, but when V.T. occurs in young people, it is difficult to find the cause. Major triggers for V.T. are explained below:

  • Previous heart attack: Each heart attack leaves scar tissues on the muscles of the heart which can lead to V.T.
  • Congenital Heart Defect
  • Hypertrophy
  • Cardiomyopathy
  • Ischemic Cardiomyopathy
  • Congestive Heart Failure
  • Myocardium

Risks with an Implantable Cardioverter Defibrillator:

Although the typical implanting of an ICD is very common and not considered too invasive, the procedure does have potential risks and complications. According to clinical practice guidelines, some of these are listed below:

  • Bleeding from the incision insertion point
  • Damage to the vessels at the incision insertion point
  • Infection in catheter site
  • Collapsed lungs
  • Repositioning of lead wires in case of dislodging
  • Tearing of the heart muscles

Difference between ICDs and Cardiac Pacemakers:

An ICD is a small stopwatch-sized electronic device. It is implanted in the skin under the collarbone. It is programmed to automatically treat major cardiac diseases such as ventricular fibrillation and dysrhythmias using ventricular pacing. It was specifically designed to treat ventricular tachyarrhythmias.

Before the ICD, it was difficult to save the life of patients at risk for sudden cardiac death. The invention of implantable cardioverter defibrillators revolutionized the method of proactively treating cardiac disorders.

A pacemaker is also a small electric device designed to provide continuous electric pulses to the heart when myocardial electrical activity is absent or too slow. It is also implanted in the chest in the skin under the collarbone.

A pacemaker is designed for a specific ventricular pacing task but implantable cardioverter-defibrillator functions as both defibrillator and as a ‘backup pacemaker’ to retain the heart’s normal rhythm.

What are the risks of an implantable cardioverter-defibrillator?

Any surgical or medical procedure comes up with risks. Possible risks from ICD insertion are as follows:

  • Bleeding from incision or catheter insertion site. The incision is the wound or cut due to the surgical process of the ICD insertion point.
  • Damage or injury to the blood vessel at the catheter insertion point.
  • Infection or inflammation at the catheter insertion site.
  • Tearing or damage to the heart muscle.
  • Collapsed lungs.
  • Dislodging or dislocation of the ICD leads. This may require another surgery to reposition the leads at the right location.

How is a cardioverter defibrillator implanted?

ICD insertion can be performed on an outpatient basis. Procedure or surgery methods can be different depending upon the patient’s condition and your cardiologist’s practices.

Mostly, ICD insertion follows the following criteria:

  • Medical staff (Thoracic Surgeons) will ask you to remove all jewelry or the objects you are wearing, to prevent any disturbance during the surgery.
  • You will be asked to change into the hospital’s surgical gown (clothing).
  • Before starting surgery, you would be asked to fast for a specific period to avoid any disruption during ICD insertion.
  • An IV line will be inserted in your wrist or arm for inserting any medicines or fluids in your body.
  • You will be asked to lie on your back on the surgical table.
  • During the surgery, your body will be connected to an electrocardiogram (ECG) monitor, which will show the basic vitals of the working and electrical activity of your heart. The basic vitals monitored during the surgery include heart rate, blood pressure, oxygenation level, and breathing rate.
  • The operating room will be cleaned beforehand. You may also be asked to shave all hairs from your chest.
  • Large electrodes (plastic pads) are placed on the front and back of your body.
  • A sedative will be inserted through an IV before the procedure, which will help you relax. Although, you would be awake during the ICD surgery.
  • ICD insertion point (place on chest) is thoroughly cleaned with antiseptic products.
  • Sterilized cloth or sheets will be placed on the surgical area.
  • A low-level anesthetic will be given to you.
  • Once the anesthetic effect is on your body, the cardiologist will make a small cut or incision at the ICD insertion point.
  • A sheath (sort of plastic tube) is inserted in the blood vessel where the leads will be inserted and advanced to the heart.
  • It is a must to stay still during surgery so that the insertion point is not dislodged from the usual place. Keep this in mind to prevent any harm or damage to the catheter insertion site.
  • The ICD lead wire will be inserted through the sheath. The doctor will advance the lead wire through a blood vessel to the heart.
  • After the lead wire has entered the heart, it will be tested at different heart locations. Fluoroscopy (monitoring through X-ray) will be used to place lead wires at the appropriate place in the heart.
  • If you are implanting a subcutaneous ICD, a minimum of two incisions will be made at the upper and bottom of the breast bone or sternum. Then ICD lead wire is entered into the skin through incision points.
  • Just below the collarbone, the ICD generator will be inserted through an incision or surgical cut after the lead wires have been attached.
  • ECG will be continually monitored to make sure surgery is going well. Certain medical tests are then done to make sure that the device is working properly.
  • The incision sites will b closed with specific medical treatments.
  • A sterilized dressing or bandage will be applied to the surgical wound.

Implantable Cardioverter defibrillators implantation in Cardiac amyloidosis patients:

What Is New?
  • 26.9% 1-year mortality rate has been claimed in patients of cardiac Amyloidosis who got an implantable cardioverter-defibrillator implanted. This ratio is certainly higher than the patients suffering from the disease of the myocardium (associated with the electrical or mechanical disorder in dilation). These results are claimed with propensity‐matched nonischemic cardiomyopathy.
  • Patients with cardiac Amyloidosis got successful treatment after implantable cardioverter-defibrillator implantation.
  • Risk factors for death in cardiac amyloidosis patients after implantable cardioverter defibrillation implantation are so far observed to be syncope (continuous fainting), ventricular tachycardia (abnormally fast heart rate), impaired renal function (kidney working disorder), cerebrovascular (area of the brain affected by blocked blood flow or severe bleeding) disorder and diabetes mellitus (a disease in which body doesn’t produce the required amount of insulin).
What Are the Clinical Implications?
  • Cardiac amyloidosis patients with implantable cardioverter-defibrillators implanted have maximum chances of morality. Therefore, paramedics carefully select and share decision-making for a successful and lifelong implantable cardioverter-defibrillator implantation. National cardiovascular data registry is another cardiac resynchronization therapy.
  • Amyloidosis is a multisystem disease that deposits an abnormal protein to the heart. It affects the normal working of the heart. This disease becomes more complex if the cardiac disorder is involved. It happens in 50% to 60% of patients. Cardiac involvement in Amyloidosis can cause life-threatening ventricular arrhythmias, sudden cardiac death, heart failure, and conduction abnormalities (affects the normal working of S.A. node). 5% of patients have rare forms of heavy chain and apolipoprotein amyloid. At the same time, Immunoglobulin light‐chain amyloidosis (A.L.) and transthyretin amyloidosis (aTTR) increase the chances of cardiac Amyloidosis in patients.
  • Amyloidosis fibrils have pathogenic effects on the patients. It deposits extracellularly in the heart tissues. However, a history of amyloidosis fibril is more intimidating than A.L. It is significantly known for being rapidly advancing and fatal for the patients. It is thought that electromechanical disorder (detectable electric complexes) is the most common cause of sudden cardiac death in A.L. patients. But ventricular arrhythmias have the most severe effects on cardiac amyloidosis patients. Although clinical data about the usage of implantable cardioverter defibrillators are limited, ICD is claimed to be safe. It is effective in treating sudden cardiac death due to fatal arrhythmias in cardiomyopathy. It is the safest, efficient, and reliable mechanism of treating cardiac sudden cardiac death in cardiomyopathy. Cardiovascular medicine is also used for such patients.
  • Researches and studies held in the past to evaluate the mortality rate in patients with cardiac Amyloidosis with implantable cardioverter-defibrillator were limited and didn’t have any essential consequences. It was partially due to fewer methodologies used for single-center and multicenter retrospective studies. (according to recent studies)Cardiac amyloidosis patients depending upon restricted evidence and undetectable advantages, require individual decision-making sessions associated with implantable cardioverter defibrillators implantation. Moreover, current studies are against ICDs implantation in cardiac amyloidosis patients with less than 1-year survival rates. But some paramedics of mortality rates in patients with cardiac Amyloidosis and ICDs are often wrong. Cardiac resynchronization therapy such as the national cardiovascular data registry is also used as secondary prevention for thoracic surgery.

Health outcomes after ICD shock:

There is always a long debate that ICD therapies can increase mortality rate in selected Heart failure and left ventricular systolic dysfunction patients because it can stop arrhythmic sudden cardiac death with quick defibrillation. Furthermore, some researchers also claim that a prolonged life after ICD shock has its own cost and can lead to adverse consequences.

While some studies state that the healthy life of patients who have experienced implantable cardioverter-defibrillator shock is affected adversely, whether they are suitable for it or not. According to recent studies, patients who received a shock in a specific time assessment had a lower health-related quality of life. But the patients who didn’t receive a shock in the given time assessment have a better health-related quality of life. Thus, patients who received shock were observed to have poorer health both mentally and physically.

Psychological diseases also relate the implantable cardioverter-defibrillator shocks. 24% to 87% of patients who experienced implantable cardioverter-defibrillator shock were diagnosed with high and worsened symptoms of anxiety disorders. Furthermore, patients who got more implantable cardioverter-defibrillator shocks were significantly observed to be more depressed and anxious as compared to other patients receiving only one ICD shock. Thus, more than 5 shocks of implantable cardioverter-defibrillator in patients lead to high leveled anxiety (constant feeling of fear and dread in minimal situations) and other psychological disorders.

Professors interviewed about 90 patients with implantable cardioverter defibrillators, whose main goal was to diagnose anxiety disorders. About 16.7% of patients had panic disorders or agoraphobia, and this ratio is significantly higher than compared to the general population.

Patients who received ICD shock had a 21% ubiquity of being diagnosed with anxiety disorder. While a ratio of 6.9% commonness in those patients without an implantable cardioverter-defibrillator shock. Implantable cardioverter-defibrillator shock greatly contributes to the psychological disorders of the patients. Hence, patients having implantable cardioverter-defibrillator have relatable maximum rates of psychological distress. There isn’t any study claiming that psychological distress occurs only in the patients who suffer inappropriate implantable cardioverter-defibrillator shock.

Other than psychological disorders, implantable cardioverter shocks have maximized the risk of heart failure hospitalization. Patients with left ventricular systolic disorder had a high rate of hospitalization due to ICD shocks. According to approved research, the risk of heart failure hospitalization in one year for ICD patients was about 26% to 31%. But if we compare it to the patients without ICD, then the ratio certainly decreases to 19%.

Current clinical trials have been succeeded in finding the relevance between implantable cardioverter-defibrillator shock and mortality. Both inappropriate and inappropriate ICD shocks were significantly fatal to mortality and rapidly advanced the risk of death. At the same time, a 20% increment of mortality was observed in ventricular arrhythmias related to implantable cardioverter-defibrillator therapies. Although, no oscillation was observed in the mortality rate of patients with ATP-treated arrhythmias. The most severe reason for death in implantable cardioverter-defibrillator patients was progressive heart failure aftershock.

Studies show various disputes over the relevance between ICD shock and bad outcomes. The dependence between both is still unclear. A possible description for the relevance is that ICD shock can have bad outcomes by giving rise to myocardial injury. It is also often observed that patients with low health status experience ventricular arrhythmias. However, it is claimed that ICD shock is a marker rather than a negotiator of adverse consequences.

Methods to reduce the incidence of ICD shock

ICD Programming:

ICD usually uses pacing stimulation tactics for the termination of tachyarrhythmias. Antitachycardia pacing is highly effective and safe than ICD shocks. In this technique, ICD provides relatively high ventricular paced beats than the underlying arrhythmia. ATP can effectively stop reentrant arrhythmias, even monomorphic V.T.s as fast as 240/min, which leads to restriction of need for shocks in many cases. Studies prove that anti-tachycardia pacing can prevent more than 90% chances of spontaneous ventricular arrhythmia. ATP also has various benefits over shocks like less patient discomfort, lower risks of adverse outcomes, and less battery usage. ATP is highly suggested as preliminary therapy for many monomorphic V.T.s. Otherwise, it shouldn’t be used.

Two specific programming techniques have been devised to reduce the requirement of ICD shocks to prevent its bad outcomes. The first one is ATP for V.T. faster than 200/min; it has been traditionally used to treat patients due to safety concerns. It comes up with the following outcomes:

  • decreased need for ICD shock
  • better and improved quality of life
  • relatively low risk of V.T. acceleration
  • little risk of syncope (fainting due to temporary drop in the amount of blood flowing to the brain)
  • no effect of mortality

The second programming strategy is the aggressive use of ATP, SVT discriminators. It led to a high-output first shock compared with a historical control cohort of patients. It lowered the risk for any shock during the first year (8.5% vs. 16.9%) for the patients who had ICD parameters programmed at the discretion of their physician.

Recent studies evaluated more severe ventricular arrhythmia detection algorithms. Studies also claim that more stringent use of ATP would reduce inappropriate therapies once ventricular arrhythmia is detected. Patients included in this study reduced the first and total occurrence of both appropriate and inappropriate therapy. Patients who followed these two programming strategies did not have any effect on their mortality rates.

V.T. tends to be sudden in the beginning and is somewhat stable. Sinus tachycardia advances gradually and has low stability. Studies claim that strategizing sudden beginning and stability criteria can help discriminate supraventricular arrhythmias and reduce the chances of inappropriate shock. Moreover, surface QRS during V.T. is more complicated and generally differs from that during sinus rhythm. Discrimination algorithms can detect the differences in the contour of the sensed intracardiac electrograms compared with a template of the electrograms during the known normal rhythm of the heart. However, all ICD devices are already programmed, but still implanting clinician must prefer reviewing the device settings beforehand because the settings may not be suitable for the individual patient. Randomized clinical trials that cardiac resynchronization therapy can be taken as secondary prevention from atrial fibrillation or heart failure trial. Transcatheter aortic valve replacement is also introduced in heart failure trials as primary prevention.

 Dual-Chamber ICDs:

A dual-chamber ICD can theoretically help differentiate between Supraventricular tachycardia and ventricular tachycardia by sensing the knowledge to discriminate between these two types of arrhythmias. If you can spot atrioventricular dissociation, it can lead to helping you in distinguishing ventricular tachycardia from supraventricular tachycardia. It can be done by using surface electrocardiography but also via the sensed device electrograms.

The main theme for this tactic is that a ventricular rate of 200/min with an atrial rate of 75/min would be constant with ventricular tachycardia (V.T.); in contrast, a ventricular rate of 109/min with an atrial rate of 350/min recommends Supraventricular tachycardia (SVT). However, studies proving the effective results (at reducing the risk of inappropriate ICD shocks) of dual-chamber ICD are much limited.

Moreover, the apparent advantages of dual-chamber ICD devices are worth the costs. These devices are more expensive and likely relate to higher periprocedural complication rates than single-chamber ICDs.

Pharmacologic Therapy:

It is stated that some specific antiarrhythmic medications tend to reduce the frequency and intensity of ICD shocks. This mechanism can allow patients to tolerate V.T. better hemodynamically, thereby allowing for broader use of ATP. The mechanisms of benefit come up with:

  • defeating atrial
  • suppressing ventricular arrhythmias
  • gradually slowing episodes of V.T.

The risk of heart failure hospitalization mortality among patients with LVSD can be reduced by evidence-based heart failure therapy having beta-blockers, angiotensin-converting enzyme inhibitors, and aldosterone receptor antagonists. Evidence-based heart failure therapy is not much used on patients eligible for ICD implantation, which in turn may add to the trouble of ICD shocks.

However, optimal ranged medical therapy can improve left ventricular systolic function such that ICD therapy may no longer be warranted. In addition, this therapy also improves symptoms of heart failure, mortality, and the risk of ventricular arrhythmias, resulting in ICD therapies. Beta-blockers would also decrease the ventricular rates in patients with supraventricular arrhythmias such as A.F. It could prevent unsuitable ICD shocks.

Only optimal heart failure therapy may not be sufficient to avoid ICD shocks. In recent researches, randomized trials were done to compare the effects of β-blocker alone, amiodarone, and a β-blocker, or sotalol. In individual trials, 40% of patients treated with β-blockers alone had shocks at about 1 year, while those nursed with amiodarone and β-blockers had only a 10% risk. Hence, left ventricular systolic disorder patients should receive optimal heart failure therapy. In some selected LVSD patients, receiving additional cardiac rhythm control therapy may be validated.

Antiarrhythmic (cardiac rhythm abnormalities) medications also have some restrictions. Sotalol has about a 1% to 4% risk of triggering torsades de pointes, which occurs especially within patients who intake higher doses, with higher creatinine levels and a history of V.T. or heart failure. Furthermore, Amiodarone results in various significant and rarely severe extracardiac toxic effects. Thus, the addition of antiarrhythmic medications should be individualized after monitoring the number of shocks, the pros & cons of these shocks on the patient, and the risk of bad effects of the medications.

Catheter Ablation:

Ventricular arrhythmias are also treated with catheter-based ablation techniques. The traditional indicator for ablation is V.T. not yielding to medical therapy treatment in patients who also receive multiple ICD shocks. The prudent usage of this technique on the rate of ICD therapy in secondary prevention patients was examined in random order to either catheter ablation using a substrate-based approach or no ablation. Patients who received catheter ablation had 65% less risk of receiving ICD therapy and 73% less risk of receiving shocks. Furthermore, catheter ablation had no significant effect on the quality of life or mortality rates. Catheter ablation was conducted only at highly experienced centers. As it is highly operator dependent, therefore, is not widely available. In addition, no general adverse effects of catheter ablation were reported, yet the procedure inherently had multiple potential complications. Catheter ablation techniques shouldn’t be observed as prophylaxis to decrease ICD therapy because of a lack of evidence and clinical trials in this regard.

Optimizing Evidence-Based ICD Implantation:

Patients who do not go through implantable cardioverter-defibrillator implantation will ultimately not receive ATP or shocks. Any technique to reduce the unsuitable device therapies should initially ensure that the decision to implant an ICD is based on established indications outlined in the relevant clinical guidelines. Rigorous adherence to current evidence in deciding patients for ICD implantation will ensure that the benefits of the treatment would be more than the risks of therapy (including risks of inappropriate shocks). A recent study claims that the strategy for patient selection for primary prevention ICD therapy needs improvement.

Moreover, a selected patient received multiple inappropriate ICD shocks for sinus tachycardia while exercising. During ICD implantation, the programmer’s default programming settings are often used, including a lower-limit V.F. zone starting at 180/min. The implantable cardioverter-defibrillator was reprogrammed to a higher-threshold heart rate for the V.F. zone, and his β-blocker dose was increased to reduce the risk of inappropriate ICD shock. The selected patient has since been free of inappropriate ICD shocks while maintaining his active exercise sessions.

Implantable cardioverter-defibrillator surely minimizes the risk of Sickle Cell Disease (SCD) and can exclusively increase the lifespan in selected high-risk patients. Patients also need to understand that many with ICDs receive a shock. But the benefit of the device surely results from its treatment of malignant ventricular arrhythmias. Unfortunately, shocks can be nonlethal rhythms (inappropriately delivered) as well. Furthermore, both appropriate and inappropriate shocks affect health status and can have other important health outcomes.

ICD and sudden cardiac death:

Sudden death due to cardiac arrest is a significant health problem that affects almost 500 000 people in the U.S. annually. An implanted automatic defibrillator can treat malignant ventricular arrhythmias.

Clinical trials prove that defibrillator therapy has improved survival in high-risk populations. Cardiac death is a diversified problem, yet defibrillator therapy has been proved beneficial for the population’s mortality with ischemic heart disease. Prophylactic therapy of ICD becomes the single best option when the left ventricular ejection fraction of 35 percent or less is found. That is why patients having a life-threatening heart disease should benefit from defibrillator therapy.

The best step to select patients at risk of cardiac death (who can get the most out of ICD implantation) is assessing ejection fraction. For optimal care, a cardiologist must understand and evaluate each patient’s ICD type, indication, cardiovascular condition, and etiology of heart disease.

Moreover, the circumstancing relevant to the index event can easily be discovered if ICD was implanted as secondary prevention. Assessment of defibrillator shocks is done to judge the evaluation of the patient’s cardiovascular conditions carefully. If you experienced or felt appropriate or inappropriate ICD shocks, you should first consult your cardiologist or some subspecialist. Device interrogation can also be conducted to properly check and facilitate the management of ICD or cardiac pacemakers.

Major risk factors for sudden cardiac death:

Some common risk factors for sudden cardiac arrest are discussed below:

1. CAD

CAD is a significant reason for angina (chest pain), myocardial infarction (heart attack), and even cardiac arrest (sudden stopping of the heart). Myocardial infarction or heart attack often occurs due to severe coronary artery disease. Myocardial infarction highly triggers ventricular fibrillation and sudden stopping of the heart. Another adverse fact is that a heart attack often leaves scar tissues in the heart of the victim. Electrical short circuits due to improper working of S.A. node around the scar tissue can trigger abnormalities in the victim’s heart rhythm.

2. Acute MI

Acute myocardial infarction occurs when there is a blockage that affects the oxygen-rich blood from reaching the heart. This significant cardiac complication often occurs in patients without risk factors. Clinical trials claim that they had once experienced cardiac arrest in a patient due to acute myocardial infarction without any risk factors during the process of head and neck reconstructive surgery.

3. Heart Failure

A typical difference between cardiac arrest and heart failure is that heart failure often happens gradually, while cardiac arrest occurs immediately often without warning. Heart failure can lead to cardiac arrest and arrhythmia. Ischemic or nonischemic cardiomyopathy causes reduced left ventricular ejection fraction, which results in the sudden stoppage of the heart.

  1. Arrhythmia

An arrhythmia occurs when a patient experiences an abnormal heart rhythm. Abnormal heart rhythm means that the patient’s heart rate becomes too fast or too slow, which leads to various adverse effects. Some versions of arrhythmia are brief and harmless. But some kinds of arrhythmia can trigger sudden cardiac arrest. Arrhythmia in the lower chamber of the patient’s heart (ventricle) is the most common heart rate that causes sudden stoppage of the heart. It includes prior sustained or nonsustained ventricular arrhythmias.

Some relatively less common risk factors for cardiac arrest are given below:

1. Structural Heart Disease:

Structural Heart diseases include Arrhythmogenic right ventricular dysplasia, Hypertrophic cardiomyopathy, Coronary circulatory anomalies, Congenital heart disease, Severe left ventricular hypertrophy, and Myocarditis. These symptoms or risk factors are relatively less common, but still, there are some chances that these diseases may trigger cardiac arrest.

2. Electrical disease

The electrical disease can be due to long Q.T. syndrome, drug-induced Q.T. prolongation and polymorphic ventricular tachycardia, Brugada syndrome, Complete heart block, catecholaminergic polymorphic ventricular tachycardia, preexcitation syndrome, chest wall trauma, and primary electrical disease. These symptoms are also part of less common factors of sudden cardiac death.

How long can you live with an ICD implant?

Pacemakers and ICD devices can mostly last 5 to 7 years or longer. Its lifespan depends upon the usage and type of pacemaker or ICD device. There are various examples in the world that prove you can lead a normal life with an ICD. The latest updates in technology have reduced the chances that other electronic devices (such as microwaves, T.V., etc.) could affect your device. But still, you must follow the precautionary measures when you have a pacemaker or ICD.

What precautions should you take with your pacemaker or ICD?

Here’s a brief description of the precautions you need to consider. You can get further details about these from your doctor.

  • Patients with ICD or pacemakers are all safe to go through airports or other security detectors. Some patients have the wrong idea that their device can’t bear the closeness of any security detector. But the fact is that security detectors will not have many adverse effects on your implantable cardioverter defibrillator or pacemaker device. The implantable cardioverter-defibrillator may set off the alarm of security detecting devices. Further, if the security team wants to have a more detailed search on you, politely tell the staff not to hold the handheld metal-detecting wand over the pacemaker for a long time (more than a second or two). This precaution is suggested because the magnet inside the wand will temporarily stop the operating mode of your implantable cardioverter defibrillator or pacemaker. Remember to not stay with the detecting device longer than needed. Although it will not have much effect, still precautionary measures should be followed.
  • Restrict yourself (or keep long distance) from magnetic resonance imaging (MRI) machines or other large magnetic fields. It is advised because magnetic fields adversely affect the programming or function of an ICD generator or pacemaker. Also, rapid commute in the magnetic field within the MRI scanner can cause heat in the pacemaker or ICD lead. Many other options have been devised to do MRIs of patients with ICD or pacemakers. But if your doctor claims that you can get an MRI scan, then go for it. Make sure to discuss it with your cardiologist. Even if you get permission to get MRI, during the process of an MRI scan, you should be closely monitored by a cardiologist. The cardiologist should have a pacemaker programming device immediately available. Advanced versions of pacemakers and ICDs can have an exception from MRI damage. Still monitoring and certain precautions are a must to be followed.
  • Strictly avoid diathermy! Diathermy is a new procedure to provide heat in your muscles to treat them. Diathermy is also known as “deep heating” due to its unique method of giving heat under the skin’s surface. The heat from the diathermy can have adverse effects on the pacemaker or ICD generator.
  • As discussed above, magnetic fields disturb the normal working of subcutaneous ICD or pacemaker. While working on large motors, including machinery (such as cars, boats, factories), make sure to turn them off. As large motors largely depend upon magnetic fields and generate a real strong magnetic field. Therefore ICD patients are advised to stay away from devices generating a magnetic field. The magnetic fields can be a big threat for ICD patients. Activation or a close approximation of ICD patients with a magnetic field can give rise to asynchronous pacing in pacemakers and transient or permanent disabling of tachycardia therapies in certain ICD systems.
  • Similarly, high voltage or radar electronics (such as radio or T.V. transmitters, arc welders, high-tension wires, radar installations, or smelting furnaces.) should also be prohibited. The electric field generated by these devices would ultimately disturb the proper functioning of the pacemaker and ICD registry. Close interaction with these devices causes significant symptoms in ICD patients and appropriate ICD therapy or device. Thus, remember to not linger around EAS systems longer than required. Avoid leaning against the system’s sensors.
  • Apparently, cell phones available in the U.S. (less than 3 watts) are safe for patients having ICD implants. Still, it is advised to keep mobile at least 6 inches distance from your pacemaker or ICD leads. Most importantly, restrict yourself from carrying cell phones in your breast pocket, as it is much closer to your pacemaker or ICD registry. Pacemakers or ICD leads could mistake the radio waves from your cell phone as a cardiac signal. This could lead to confusion and disturbance in devices and can cause cardiac rhythm abnormalities.
  • Further, MP3 player headphones or handsfree also have magnetic substance. This magnetic substance will also affect the working of ICD lead or pacemaker. In order to stop the interference of MP3 magnetic substance, it shouldn’t be in very close contact with a pacemaker or subcutaneous ICD. Headphones should be kept at about 1.2 inches from a pacemaker or subcutaneous ICD. If you adjust them properly in your ears while keeping a distance from the device, they will not pose any risk. Never drape headphones around your neck, never put them in your breast pocket and never let any person with headphones come very close to your pacemaker or ICD registry.
  • While having any kind of surgical procedure by a surgeon or dentist, make sure to tell him that you have a pacemaker or ICD implanted. This is suggested because various surgical procedures require the ICD registry to be turned off or programmed to a special mode. You can ask your cardiologist in such a case. Qualified medical personnel could be appointed to change the mode of pacemaker temporarily. This process can be done without any surgery.
  • Shock wave lithotripsy is another medical therapy that should be done carefully not to affect the ICD treatment. Lithotripsy is done by generating magnetic and electrical fields. As discussed before, magnetic and electric field lines interfere with the working of ICD and can ultimately cause abnormal heart rhythm. Before having any kind of medical treatment, make sure to share the history of implantable cardioverter-defibrillator with your attending doctor. In this way, he will know which therapy is not suggested for ICD patients. Thus, before scheduling any surgery or wave treatment, make sure to discuss it with your cardiologist and surgeon.
  • Transcutaneous electrical nerve stimulation is another treatment method that confuses the normal working of implantable cardioverter-defibrillator (ICD). It is stated that in various cases, TENs have caused ICD patients to have sudden inappropriate shock, which could lead to cardiac arrest. Although TENs are used to cure certain pain conditions, this treatment can have aggressive effects for a person with an implantable cardioverter-defibrillator (ICD). Make sure to discuss with your cardiologist or attending doctor before receiving TENs therapy to avoid any adverse consequences.
  • Various times, it has been stated that any electromagnetic or traditional waves are a bad fortune for ICD and pacemakers. Therapeutic radiation therapy could be essential for some patients with ICD implants. As Therapeutic radiation is used to cure cancer, so it can’t be avoided. But Therapeutic radiation will directly have adverse effects on implantable cardioverter-defibrillator (ICD). It will extensively damage the circuits of ICD, resulting in sudden death or sudden cardiac arrest. As the dosage of radiation is increased, the risk for bad effects on ICD also increases. You can discuss it with your cardiologist to devise some appropriate precautions in such a matter. Thus, before undergoing Therapeutic radiation, make sure to inform your doctor that you have an implantable cardioverter-defibrillator (ICD).
  • Make sure to carry your verified I.D. card stating that you have a pacemaker or implantable cardioverter-defibrillator (ICD). If you have an implantable cardioverter-defibrillator (ICD), it is suggested that you must always wear a medic alert bracelet or necklace. It will have a massive effect on keeping you away from cardiac arrest or sudden death.

You can always consult your cardiologist if you have any questions about preventive measures or if you are not sure whether you can have a certain surgery or not.

Can you participate in regular, daily activities with a pacemaker or ICD?

Before undergoing ICD implants, it might be difficult for you to make up through your daily activities. But after you have succeeded in ICD implantation, you can do the same daily activities everyone else of your age is doing. Although your daily activities will be quite limited until the incision (wound or cut from the surgery) is completely healed. No worries, as this limit will not be more than 3 weeks, depending upon the aftercare and your cardiologists’ instructions. ICD or pacemaker patients would be able to do the following activities:

1. Exercise:

Once you have your ICD or pacemaker implanted, you can continue your daily activities after a few days of rest. Exercise is the most important factor of daily life in order to stay healthy. Don’t worry, as you can easily continue your daily exercise with ICD or pacemaker. Initially, your cardiologist will suggest you some light exercise that will help you live a healthy life. Later, you can increase the intensity of exercise according to your doctor’s instructions.

2. Driving:

Driving is another important activity of daily life which can’t be ignored. People highly depend on the driving vehicle in order to reach any destination. Once you are cleared (permitted) by a doctor, you can drive your vehicles. However, some legal laws may prevent you from driving. This restriction will be for the first 6 months after you have got your ICD implants. This restriction is because the device may get fired, which will lead to abnormal heart rhythm. This may further lead to fainting or cardiac arrest. Also, patients with ICD cannot get a commercial driver’s license, according to law restrictions.

3. Return to work:

Working is the basic need of life, as you need to earn to fulfill your life’s needs. There are myths about ICD implantation that you can’t work properly after the process. But these are all false ideas. After the prescribed amount of rest, you can get back to work like everyone else. ICD implantation will not become a hurdle in your work life.

4. Sports and recreational activities:

Another common myth about ICD and pacemakers is that patients can’t involve themselves in sports or other recreational activities. It is completely wrong. However, ICD patients can naturally involve themselves in sports and other activities. Although patients should make sure not to put much pressure on the chest as it may affect the working of their ICD or pacemaker. If you get a pressured blow on your chest, make sure to see your cardiologists to check that your device’s functioning is not damaged.

Moreover, you can make it through a shower and baths as well. If you have any confusion about a certain daily activity, make sure to ask your cardiologist.

How can you ensure that my pacemaker or ICD is working properly?

Implantable defibrillators are built to last for at least 5 to 7 years. But you should still get a regular check-up to make sure that your implantable defibrillators are working properly. Schedules for checking devices may differ in different cardiologist centers. Some advanced implantable defibrillators can be monitored at home remotely over a telephone or internet connection. The manufacturers of the implantable defibrillators provide all equipment required for the monitoring system of the device. Other than remote monitoring, your cardiologist will also schedule an in-person device check after specific intervals. If there is any change required in the settings, it must be done by a trained medical professional using a device programmer.

A device interrogation is used to check or monitor lead wire condition, battery life, and other functions. Interrogation is done by connecting ICD with the detecting device. This connection is done noninvasively without any surgery. A special wand-like device is placed on the skin where ICD is implanted. ICD and detecting device is connected in this way. Data recorded by ICD is transmitted from the device to the programmer, and further specifications are evaluated. In-home or remote interrogation device systems usually have wireless technology connections to special equipment that evaluates the necessary data and sends it to your cardiologist.

Your cardiologist may also ask you to record your pulse rate periodically. Inform your cardiologist of any unusual symptoms or symptoms similar to those you had before undergoing ICD implantation. Make sure always to consult your cardiologist for more information, if needed.

How to check your pulse?

You must know ‘how to check your pulse’ in order to record it after specific intervals. The heart is considered the most important part of the body because it pumps blood throughout the body. As the blood pumped by the heart reaches the arteries, heart-pumping beats can be felt by firmly pressing over the arteries. Arteries are located near the bare surface of the skin at certain locations on the body. Pulse can easily be detected on the inside of the elbow, on the side of the lower neck, and at the wrist.

You can read your pulse by following tips:

  • Look for the trace of arteries on your wrist. Put the first and second fingertips firmly but gently on the arteries unless you can feel a pulse.
  • Start observing the pulse when the clock’s second hand is on twelve. Start counting the pulse.
  • Calculate the number of pulses for 60 sec (or 15 sec, then multiply it by 4 to find pulse rate in 1 minute or beat per minute).
  • Another thing to note is that do not look on the watch again and again, rather than focus on counting the pulse.
  • If you are confused with the result of pulse reading, ask any other person to count it for you.
  • Radial artery (pulse on the wrist) is probably better to check pulse rate. While carotid artery (pulse on the neck) is difficult to count the pulse rate. But if you want to check through the pulse on the neck, make sure not to press hard against the neck. Never press the neck from both sides as it can cause the person to pass out or faint.


Defibrillator therapy has great benefits for the survived victim of sudden stopping of the heart. Implantation of ICDs is increasing day by day in people at high risk of sudden termination of working of the heart. An ICD reduces the risks of sudden death from immediate heart stoppage more than any cardiac medication.

Sometimes ICD shocks can be disturbing; such an unsettling feeling is a sign that your ICD effectively treats abnormal heart rhythm and keeps the patient safe from sudden death. Consult your cardiologist about how to care for your ICD.

The lithium battery used in ICD devices can last about 5 to 7 years. The battery will be observed thoroughly during the regular checkups after specific intervals (mostly after six months). If the battery seems to be nearly out of power, the ICD generator is changed with a new one. A minor outpatient procedure does this replacement.

ICDs and end-of-life issues

Even if the patient with ICD becomes terminally ill, ICD will still continue its therapy and provide ICD shocks if required. ICD should be deactivated in order to terminate ICD shocks. The cardiologist does a small procedure to turn off the device if desired. Deactivating ICD will lead to the prevention of unwanted shocks and unnecessary tolerance. This process won’t stop your heart suddenly.

Consult your cardiologist if you want deactivation of ICD. Also, discuss your wish with your family members or guardian who makes medical decisions for you about what you could in an end-of-life care situation.


Can ICD cure abnormal heart rhythm?

The simple answer to this question is “No.” You might be wondering why! Let me explain. Cure means permanently elevating or eliminating the condition. That’s proving cure is not a function of ICD. ICD is used as part of a cardiac patient’s treatment. It automatically detects the cardiac disorder and applies the appropriate therapies to normalize the heart rate.

Does ICD treat all rhythm disorders?

No! as ICD is programmed to treat acute cardiac or rhythmic disorders. It is particularly programmed to treat lower chambers or portions of the heart. Many technical types of research are done to create a new version of ICD that can treat all rhythmic problems. A good rhythmic condition can often be attained by the medications only. But if the situation worsens, consult your cardiologist. Your doctor will perform an EP study on you to know more about your cardiac condition. Your doctor will discuss if you require ICD insertion.

Do shocks from ICD hurt?

ICD shocks are never observed as painful. However, the experienced persons state that ICD shocks give an unsettling feeling, not painful. ICD usually delivers a shock to treat abnormally fast heart rate. The shock is given instantly without any delay to get the normal rhythm back.

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