Brandenburg Heart Center near Berlin – Cardiology, Cardiac Surgery and Home Monitoring
An implantable cardioverter defibrillator (ICD) – or automatic implantable cardioverter defibrillator (AICD) – is used to monitor and treat patients with malignant tachyarrhythmia (e.g. ventricular fibrillation), providing protection against sudden cardiac death.
Ventricular fibrillation is one of the most dangerous types of cardiac arrhythmia. When it occurs, a defibrillator can save a patient's life by delivering a strong electric shock to the heart.
This results in all the cells of the heart muscle being stimulated at the same time, and allows normal sinus rhythm to be restored.
Patients at a high risk of ventricular fibrillation or other malignant cardiac arrhythmias can now be fitted with miniature defibrillators (ICDs), with the process of implantation similar to that of a pacemaker.
On 4 February 1980, the first successful implantation of an automatic defibrillator was carried out at the Johns Hopkins Hospital in Baltimore by American cardiologist Michel Mirowski.
Following this event, the automatic implantable defibrillator – and later the automatic implantable cardioverter defibrillator (ICD) – became one of the most successful therapeutic devices used within the field of cardiology.
What conditions can be treated using an implantable cardioverter defibrillator?
- Primary ventricular fibrillation
- Ventricular tachycardia
- Heart failure with decreased ventricular function (LVEF ≤ 35%)
The use of defibrillators is recommended primarily in patients with heart failure, in order to prevent sudden cardiac death as a result of dangerously fast tachyarrhythmias (LVEF ≤ 35%). The implantation procedure is similar to that used with pacemakers.
Defibrillators continuously monitor the patient's heart rate and, if necessary, are able to terminate an episode of tachyarrhythmia (a dangerously fast and irregular heart rate) by either delivering quick electrical impulses that stimulate the heart muscle (known as fast pacing or antitachycardia pacing) or by delivering an electric shock. Many defibrillators can also measure and record additional parameters, such as patient-activated recordings, other types of arrhythmias, intrathoracic impedance (resistance) through the lungs and, where appropriate, details of any action taken by the device. Combined with home monitoring (remote monitoring), this can help to improve the patient's cardiac rhythm management. The effectiveness of individualized cardiac rhythm management depends on the quality of individualized programming and device management, which can help to ensure that potential problems are detected early and addressed without delay.
- Assessment with regard to patient's suitability for treatment with an implantable device and selection of the type of implantable pacing device to be used in line with the patient's requirements; information and consent procedure, including discussion with the patient and written consent.
- Implantation of the ICD under local anesthesia.
- The device's main lead is positioned in the tip of the right ventricle, in direct contact with the heart muscle.
- An alternative approach to implantation has recently become available for cases where the patient's anatomy or scar tissue from a previous surgical procedure prevents the lead from being advanced into the right ventricle. In these cases, a subcutaneous ICD can be used, which is implanted in a subcutaneous pocket (under the skin) and can deliver an electric shock to defibrillate the heart without the need for a lead to be implanted into the ventricle.
Chest x-ray following the implantation of an ICD: the defibrillator lead has been advanced to the tip of the right ventricle.
At the Brandenburg Heart Center, the implantation of cardiac pacing devices forms an integral part of our approach to the treatment of cardiac arrhythmias.
Every year, we implant approximately 100 single and dual chamber ICD systems – which have one and two leads, respectively – and approximately 100 biventricular ICD devices, which have three leads (cardiac resynchronization therapy with ICD).
Johns Hopkins Pathology
SCD Research at Johns Hopkins
The Johns Hopkins Hospital has a long history in sudden cardiac death research. Dr.
Michel Mirowski invented the implantable cardioverter-defibrillator (ICD) while working at Sinai Hospital in Baltimore which is an affiliate of Johns Hopkins. Many of his early papers were written with Dr.
Helen Taussig, internationally known for her work with “blue babies” and Myron Weisfeldt who became the Chairman of Medicine at Johns Hopkins Hospital.
Prominent sudden cardiac death research continues to this day, particularly in the area of genetics. Dr. Dan Arking is a geneticist who has achieved wide recognition for his discovery of many genes involved in regulating electrical properties of the heart, including the PR, QRS, and QT intervals.
Some of these genes also influence the risk of sudden cardiac death, and characterizing the biological role of these genes is under investigation. Dr.
Arking is also using genome-wide association studies (GWAS) to identify specific genetic changes that make an individual more ly to die of sudden cardiac death.
Dr. Marc Halushka is a cardiovascular pathologist who has studied a variety of cardiovascular diseases ranging from aortic aneurysms to sudden cardiac death. Dr.
Halushka has taken a technique commonly used in cancer research – the tissue microarray – and has adapted it to cardiovascular research questions.
He is now focusing his efforts on using tissue microarrays for sudden cardiac death research.
Research Program of:
Dr. Arking has published extensively on many causes of cardiovascular disease. His more recent focus has been on genetic causes of sudden cardiac death. A complete list of publications can be found here. Learn more about his research at his faculty web page.
GWAS Studies +
The goal of this research is to identify genes and specific genetic changes that influence risk for sudden cardiac death.
From the standpoint of preventive care, SCD poses a huge burden since less than 10% of SCD victims survive, and approximately 2/3 of SCD victims do not have clinical symptoms that would warrant preventive intervention.
Thus, the use of genetics to identify individuals who are at high risk for SCD is crucial.
Traditional approaches to identify genes have relied upon screening candidate genes or family-based studies in families with rare single-gene forms of disease (S/LQTS, ARVC/D, Brugada syndrome). Given the limited success of these approaches to identify genes contributing to common forms of sudden cardiac death, Dr.
Arking has pioneered the use of genome-wide association studies (GWAS), which allow for an unbiased screen of virtually all common genetic variants in the genome. These have directly lead to the identification of at least 2 genes involved in SCD, NOS1AP and BAZ2B.
He is currently participating in an international collaboration to increase the available SCD samples for GWAS, which is critical to identifying additional genes.
Dr. Arking is also currently developing improved GWAS methodology, as well as exploring the use of additional genome-scale data, including gene expression directly from hearts obtained at autopsy, to improve the power to both identify SCD risk genes, and understand how modification of these gene products influences risk of SCD.
TMA Studies +
Wolf-Parkinson-White (WPW) is a rare disease in which the electrical conducting system of the heart is abnormal. A normal heart has two “pacemakers” that keep the heart beating synchronously. They are called the sinoatrial (SA) node and the atrioventricular (AV) node.
They are usually connected to each other by a single conducting pathway. There are two pathways the AV node, which pass through the bundle of His and are called Purkinje fibers. In WPW, there is an accessory pathway, known as the bundle of Kent, that bypasses all or part of the typical AV node conduction system.
This can cause the heart to get “confused” as it can recieve different signals on when to beat. This results in a preactivation contraction and can cause tachyarrhythmias (accelerated heartbeats) and a typical appearance on the EKG of a delta wave. In some individuals this can result in sudden cardiac death.
Some individuals who have been diagnosed with WPW will actually improve and lose the accessory excitation pathway.
There are a number of different treatments for WPW, which depends on the type of reentrant pathway. Some individuals can stop arrhythmias by coughing, bearing down, or massaging the neck. Some individuals need to undergo radiofrequency ablation, in which the abnormal pathway is destroyed.
- Sotoodehnia N, et al. Common variants in 22 loci are associated with QRS duration and cardiac ventricular conduction. Nat Genet. 2010 Dec;42(12):1068-76.
- Wirka RC, et al. A common connexin-40 gene promoter variant affects connexin-40 expression in human atria and is associated with atrial fibrillation. Circ Arrhythm Electrophysiol. 2011 Feb;4(1):87-93.
- Lubitz SA, et al. Independent susceptibility markers for atrial fibrillation on chromosome 4q25. Circulation. 2010 Sep 7;122(10):976-84.
- Eijgelsheim M, et al. Genome-wide association analysis identifies multiple loci related to resting heart rate. Hum Mol Genet. 2010 Oct 1;19(19):3885-94.
- Tomas M, et al. Polymorphisms in the NOS1AP gene modulate QT interval duration and risk of arrhythmias in the long QT syndrome. J Am Coll Cardiol. 2010 Jun 15;55(24):2745-52.
- Arking DE, et al. Genome-wide association study identifies GPC5 as a novel genetic locus protective against sudden cardiac arrest. PLoS One. 2010 Mar 25;5(3):e9879
- Ellinor PT, et al. Common variants in KCNN3 are associated with lone atrial fibrillation. Nat Genet. 2010 Mar;42(3):240-4.
- Pfeufer A, et al. Genome-wide association study of PR interval. Nat Genet. 2010 Feb;42(2):153-9.
- Pfeufer A, et al. Common variants at ten loci modulate the QT interval duration in the QTSCD Study. Nat Genet. 2009 Apr;41(4):407-14.
- Arking DE, et al. Multiple independent genetic factors at NOS1AP modulate the QT interval in a multi-ethnic population. PLoS One. 2009;4(1):e4333.
- Arking DE, et al. A common genetic variant in the NOS1 regulator NOS1AP modulates cardiac repolarization. Nat Genet. 2006 Jun;38(6):644-51.
Pacemaker or ICD: Which Do I Need?
You may have heard of two little devices that doctors use to help treat heart problems: pacemakers and ICDs (implantable cardioverter defibrillators).
They use them when you have a type of heart problem called an arrhythmia. When you have it, your heart might beat too slowly, too fast, or with an irregular rhythm, depending on which kind you have.
While both devices work to help your heart beat better, these two devices are not exactly the same. Learn about what each one does, how they work, and when each would be used.
It’s a small device placed under your skin in your upper chest. The pacemaker has a computer that senses when your heart beats at the wrong speed or rhythm.
When that happens, it sends out electrical pulses to keep your heart at a steady rhythm and rate.
You might need a pacemaker if:
- Your heart beats too slow or unevenly and other treatments haven't helped.
- You have an ablation procedure. This burns off tiny areas of your heart that trigger abnormal electrical impulses. Sometimes the doctor will destroy a section of your heart called the AV node. This is where electrical signals pass from the atria to the ventricles. After this procedure, you will need a pacemaker to regulate your heart rhythm.
- You take certain heart medicines. Beta-blockers and some other heart medications can slow your heartbeat. You might need a pacemaker to speed up the beat.
Before your surgery, you might need to take an antibiotic, a type of medicine that kills bacteria. Your doctor may ask you to stop taking certain other medications, such as blood thinners. You'll need to stop eating about 8 hours before your surgery.
You'll have the surgery at a hospital. You'll get medicine to relax you and prevent pain.
The doctor will thread the pacemaker wires (called “leads”) through a blood vessel into your heart. Then, she will make a small cut in your chest. She will insert the pacemaker just under your collarbone. It contains a small computer and a battery.
Usually, it will go on the side you don't use most of the time. If you're right-handed, it will go on your left side.
Leads will connect the pacemaker to your heart. Electrical signals will travel down the leads. These signals will adjust your heart rate if it gets too slow or too fast. Your doctor will test the device to make sure it works.
Any surgery can carry the chance of complications. With pacemaker surgery, you may have bleeding and bruising. Other possible problems include:
- Damage to a blood vessel or nerve
- Punctured or collapsed lung
You may stay in the hospital overnight to make sure the pacemaker is working. You might have some pain and swelling in the area where it was placed for a few days afterward.
Most people can go back to their normal routine within a few days of getting a pacemaker. You might need to avoid lifting anything heavy for the rest of your life and playing contact sports that could damage it. Talk to your doctor about how much you can do.
Your doctor will check your pacemaker once every 6 months. During the checkup, she will make sure:
- The battery works
- The wires are still in place
- The pacemaker is keeping your heart in rhythm
Batteries need to be replaced every 5 to 15 years. You'll have minor surgery to switch them.
You need to be careful around devices that have strong magnetic fields. They could mess up the pacemaker’s signal. Limit how long you’re around them and try not to get too close. Some of these devices are:
- Cell phones and MP3 players
- Electrical generators
- High-tension wires
- Metal detectors
- Microwave ovens
Some medical procedures can also interfere with a pacemaker. If your doctor wants you to have an MRI scan or shockwave therapy for kidney stones, for instance, be sure they know you have a pacemaker and what kind you have. That information can be put on a card you carry with you.
a pacemaker, an implantable cardioverter defibrillator, or ICD, is a device placed under your skin. It also contains a computer that tracks your heart rate and rhythm.
The main difference is that if your heart beats way too fast or is very rhythm, the ICD sends out a shock to get it back into rhythm. Some also act pacemakers. They send out a signal when your heart rate gets too slow.
You might need an ICD if the rhythm of your heart's lower chambers, called the ventricles, is dangerously abnormal.
You might also need one if you've had a heart attack or cardiac arrest, which is when your heart stops working. An ICD could save your life if your abnormal heart rhythm becomes life-threatening.
You may have to take an antibiotic before the surgery. And, your doctor might ask you to stop taking certain medicines, such as blood thinners. You’ll have to stop eating and drinking about 8 hours before your surgery.
You'll get medicine to relax you and so you don't feel pain. Also, you might be given something so that you won’t be awake during the surgery.
The doctor will place the ICD wires into a vein and thread them into your heart. She will place the device in your chest through a small cut. She will test the ICD to make sure it works.
You could have bleeding or bruising. Other possible problems from ICD surgery include:
- Blood clots
- Damage to a blood vessel, nerves, or your heart
- Punctured or collapsed lung
Once your ICD is in place, it might shock your heart if it beats too fast. The shock can feel intense. You might get dizzy or faint when it happens.
Sometimes you can get shocked when you don't need it. If this happens, your doctor can reprogram your device to stop it from jolting you at the wrong time.
You'll stay in the hospital for 1 to 2 days. You won't be able to lift the elbow on the side of the ICD for 4 weeks after it's implanted. Your doctor will tell you how soon you can go back to your normal activities. You should avoid heavy lifting and contact sports that could damage the ICD.
Your doctor will check your ICD once every 3 months to make sure it works. Keep your distance from magnetic fields that could interfere with your ICD. These include:
- Motorcycle engines
- Power plants
- Chain saws
- Cell phones (hold to the ear opposite the ICD)
- Airport security
Your pacemaker or ICD will help keep your heart in rhythm. You should be able to do most of your normal activities, including exercise.
Follow your doctor's instructions and go to all of your follow-up visits to make sure you get the most from your device.
American Heart Association: “Implantable Cardioverter Defibrillator (ICD),” “What Is a Pacemaker?”
Johns Hopkins Medicine: “Pacemaker Insertion,” “Overview of Pacemakers and Implantable Cardioverter Defibrillators (ICDs).”
National Heart, Lung, and Blood Institute: “How Does an Implantable Cardioverter Defibrillator Work?” “How Will a Pacemaker Affect My Lifestyle?” “What are the Risks of Having an Implantable Cardioverter Defibrillator?” “What are the Risks of Pacemaker Surgery?” “What is a Pacemaker?” “What to Expect After Implantable Cardioverter Defibrillator Surgery,” “What to Expect After Pacemaker Surgery,” “What to Expect During Pacemaker Surgery,” “Who Needs a Pacemaker?”
Stanford Healthcare: “After You Go Home,” “Before the Procedure,” “During the Procedure,” “Follow-Up,” “Magnetic Interference,” “Risks and Success.”
Learn.Genetics (University of Utah): “What Is an Antibiotic?”
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