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Types of Cardiac Devices

Many cardiac devices are designed to help control irregular heartbeats in people with heart rhythm disorders. These irregularities are caused by problems with the heart’s electrical system, which signals the heart to contract and pump blood throughout the body.

At NYU Langone's Heart Rhythm Center, our cardiac electrophysiologists implant and monitor devices that either help the heart’s electrical system function properly or measure heart rhythm. These devices include implantable cardioverter defibrillators, or ICDs, pacemakers, and implanted heart rhythm monitors called loop recorders.

Implantable Cardioverter Defibrillator

People with heart failure are often at risk for life threatening, fast, irregular heartbeats called ventricular arrhythmias. These people may need a combination biventricular pacemaker and implantable cardioverter defibrillator, or ICD, which shocks the heart’s rhythm back to normal.

Ventricular arrhythmia occurs when irregular heartbeats originate in the heart’s ventricles, the lower chambers that pump blood to the body. When this happens, the heart stops pumping blood. If the rhythm is not corrected quickly, the result is sudden cardiac arrest—a short-circuiting of the electrical signals that control the heart’s ability to pump blood.

VIDEO: Dr. Larry Chinitz, director of the Heart Rhythm Center, explains how implantable cardioverter defibrillators are used to correct dangerous arrhythmias.

The heart usually pumps out about 60 percent of its blood with each beat—a measurement called ejection fraction. When the heart’s ejection fraction is reduced to 35 percent or less, a person’s risk for sudden cardiac arrest increases. If the reduced ejection fraction is not caused by a condition that can be treated and reversed, surgeons often implant an ICD.

In emergency situations, someone can deliver a shock from an external defibrillator, if one is available, to restore the heart to a normal rhythm. An ICD, however, detects an irregular heartbeat and automatically and internally delivers a series of pacing pulses or an electrical shock to the heart to correct the heart’s rate and rhythm.

An ICD stores information about when and how many electrical shocks are delivered to the heart, whether they corrected the arrhythmia, and the status of the device’s battery. Many ICDs have a built-in pacemaker, which sends electrical impulses to the heart when it is beating too slowly, helping it to beat at a normal rate.

People usually don’t notice small pacing impulses that correct a fast heart rate, but they do feel an uncomfortable “thump” in the chest when a shock is delivered. If you notice one of these shocks, contact your doctor.

The ICD device is surgically implanted in the chest wall below the collarbone. Surgery typically takes about an hour and requires an overnight stay in the hospital. Your doctor may restrict your activity, including driving and lifting items heavier than 10 pounds, until your follow-up appointment 2 weeks after surgery.

If you are at risk of fainting from a fast or irregular heart rhythm, driving may be restricted for longer periods of time or permanently. Your heart condition, not the implanted device, is the reason for this restriction.

The battery for an ICD typically lasts 5 to 10 years.

A new type of defibrillator, called a subcutaneous internal cardioverter defibrillator, is now offered at NYU Langone. This device does not need to be implanted within the heart or a blood vessel. The leads are implanted subcutaneously, or under the skin, which helps to avoid complications associated with the implantation of a device in a blood vessel.


A pacemaker is a small device that’s implanted under the skin of the chest. It produces electrical pulses to keep the heart beating at a normal rate. A pacemaker helps manage heart rhythm disorders, such as bradycardia, when the heart beats too slowly, or an arrhythmia, when the heart beats irregularly.

The size of two half-dollars pressed together, a pacemaker contains a small computer and a battery that are connected to one or two flexible, insulated wires called leads, which extend from the device inside the chest to the heart.

A pacemaker is implanted in the chest, beneath the collarbone during a procedure that requires local anesthesia and sedation. The surgery typically takes less than an hour to complete and usually requires an overnight stay in the hospital.

You can most likely return to your usual activities the day after pacemaker implantation, but your doctor may restrict some activities for two weeks. Restrictions include avoiding lifting anything heavier than 10 pounds and not engaging in exercises—such as swimming, golf, or tennis—that strain the affected side.

Two weeks after the procedure, your doctor examines the implantation site and checks to see how well the pacemaker is working by using a wand that transmits information stored in the device’s generator to a computer. This includes information about the pacemaker’s battery life, the condition of the lead or leads, and any arrhythmias experienced since the pacemaker was implanted. The battery typically lasts 7 to 13 years.

Every six months, you visit NYU Langone’s Heart Rhythm Center, so your doctor can retrieve and analyze the information stored on the pacemaker. Sometimes, this information can be transmitted from home via a telephone line, cellular network, or the internet. This scheduled remote monitoring allows for more frequent checkups while reducing the need for office visits to once a year.

Ongoing monitoring helps your doctor determine if the device needs reprogramming or replacing. It can also determine if another therapy, such as medication, is needed to manage a heart rhythm disorder.

NYU Langone’s Heart Rhythm Center offers a new type of pacemaker called a leadless pacemaker. The generator and a small wire are included in the 2-centimeter device, which is implanted directly into the heart via a catheter through a vein.

Biventricular Pacemaker

A biventricular pacemaker works like a conventional pacemaker, but uses a third wire to send electrical impulses to the heart to resynchronize the contractions of the heart’s left lower chamber, or ventricle.

Also called a cardiac resynchronization device, this type of pacemaker is implanted when medications don’t relieve symptoms of heart failure, a condition in which the heart does not pump a sufficient amount of blood to the body, and when the left chamber does not beat in a coordinated manner. This causes both ventricles to contract out of sync with one another. A resynchronization device coordinates the contractions of the left ventricle.

Doctors provide local anesthesia and a sedative when implanting a biventricular pacemaker. The surgery takes about two hours to complete and requires an overnight stay in the hospital. The restrictions afterward are the same as those recommended after the implantation of a conventional pacemaker.

Your doctor electronically monitors a biventricular pacemaker at NYU Langone’s Heart Rhythm Center in the same way as a conventional pacemaker.

Implantable Cardiac Loop Recorder

Your cardiac electrophysiologist may recommend surgically implanting a wireless cardiac monitor called a loop recorder, which continuously records your heart’s rhythm for up to three years. Smaller than the size of an AAA battery, this device is surgically inserted beneath the skin of the upper chest to record the heart’s electrical activity, much like an electrocardiogram, or EKG.

People who have had unexplained fainting spells or heart palpitations that can’t be detected by short term heart rhythm recording devices—such as Holter monitors—may be candidates for this device. Doctors may also recommend an implantable loop recorder for people with atrial fibrillation, which causes a rapid and irregular heartbeat. In addition, this device is used in people who have had a stroke for which a cause has not been determined.

Your doctor makes a small incision in the upper chest and inserts the device just under the skin. The surgery is brief, and you can return to your usual activities the next day. Your doctor may limit your activity until the incision heals.

Cardiac loop recorders typically monitor the heart’s electrical activity for up to 36 months before replacement is required. The device is removed through the original incision site through a short surgery that is similar to the implantation procedure.

If you experience a fainting spell or heart palpitations while this device is implanted in the chest, you or another person places a handheld recorder over the device to capture and record the heart’s electrical activity. This information is stored in the device and can be transmitted via a remote monitoring system to help your doctor determine the cause of your symptoms. The loop recorder is also able to automatically record irregular heart rhythms.

The newest implantable cardiac loop recorder is extremely small and can be injected under the skin. In this procedure, a small puncture is made in the skin to the left of the breastbone. The loop recorder is loaded into a small plastic applicator, which your doctor uses to push the device under the skin. Dissolvable sutures are used to close the small puncture. This procedure is performed with local anesthesia, and you can go home afterwards.

Our Research and Education in Cardiac Device Management in Adults

Learn more about our research and professional education opportunities.