What is an implantable cardioverter defibrillator?
An implantable cardioverter defibrillator (ICD) is
a small device that your doctor can put into your chest to help regulate an
irregular heart rhythm, or an arrhythmia.
Although it’s smaller than a deck of cards, the ICD contains
a battery and a small computer that monitors your heart rate. The computer
delivers small electrical shocks to your heart at certain moments. This helps
control your heart rate.
Doctors most commonly implant ICDs in people who have
life-threatening arrhythmias and who are at risk for sudden cardiac arrest, which
is a condition in which the heart stops beating. Arrhythmias can be congenital,
which means something you were born with, or a symptom of heart disease.
ICDs are also known as cardiac implantable
devices or defibrillators.
Why do I need an implantable cardioverter defibrillator?
Your heart has two atria, or upper chambers, and
two ventricles, or lower chambers. Your ventricles pump blood from your
heart to the rest of your body. These four chambers of your heart contract in a
timed sequence to pump blood throughout your body. This is called a rhythm.
Two nodes in your heart control your heart’s rhythm. Each node
sends out an electrical impulse in a timed sequence. This impulse causes your
heart muscles to contract. First the atria contract, and then the ventricles
contract. This creates a pump. When the timing of these impulses is off, your
heart doesn’t pump blood very efficiently. Heart rhythm problems in your
ventricles are very dangerous because your heart can stop pumping. This can be
fatal if you don’t receive treatment immediately.
You might benefit from an ICD if you have:
- a very fast and dangerous heart rhythm called
- erratic pumping, which is referred to as
quivering or ventricular fibrillation
- a heart weakened by a history of heart disease
or a previous heart attack
- an enlarged or thickened heart muscle, which is
called dilated, or hypertrophic, cardiomyopathy
- congenital heart defects, such as long QT
syndrome, which causes heart quivering
- heart failure
How does an implantable cardioverter defibrillator work?
An ICD is a small device implanted in your chest. The main part,
which is called a pulse generator, holds a battery and tiny computer that
monitors your heart rhythms. If your heart beats too fast or irregularly, the
computer delivers an electric pulse to correct the problem.
Wires called leads run from the pulse generator into
specific areas of your heart. These leads deliver the electric impulses sent by
the pulse generator.
Depending on your diagnosis, your doctor may recommend one
of the following types of ICDs:
- A single-chamber ICD sends electrical signals to
the right ventricle.
- A dual-chamber ICD sends electrical signals to
the right atrium and right ventricle.
- A biventricular device sends electrical signals
to the right atrium and both ventricles. Doctors use it for people who have
An ICD can also deliver up to four different types of
electrical signals to your heart.
Cardioversion gives a stronger electrical signal that
can feel like a thump to your chest. It resets heart rhythms to normal when it
detects a very fast heart rate.
Defibrillation sends a very strong electrical signal
that restarts your heart. The sensation is painful and can knock you off your
feet, but lasts only a second.
Antitachycardia pacing provides a low-energy pulse
meant to reset a rapid heartbeat. Typically, you feel nothing when the pulse occurs.
However, you may sense a small flutter in your chest.
Bradycardia pacing restores a heartbeat that’s too slow
to normal speed. In this situation, the ICD works like a pacemaker. People with
ICDs usually have hearts that beat too fast. However, defibrillation can
sometimes cause the heart to slow down to a dangerous level. Bradycardia pacing
returns the rhythm to normal.
How do I prepare for the procedure?
You shouldn’t eat or drink anything after midnight on the
day before your procedure. Your doctor may also ask you to stop taking certain
medicines, such as aspirin or those that cause blood clotting. Be sure to tell
your doctor about the medications, over-the-counter drugs, and supplements you
take before the procedure. You should never stop taking a medication without
talking to your doctor first.
What happens during the procedure?
An ICD implant procedure is minimally invasive. An electrophysiologist
usually implants the device in an electrophysiology laboratory. In most cases,
you’ll be awake during the procedure. However, you’ll receive a sedative to
make you drowsy and a local anesthetic to numb your chest area.
After making small incisions, the doctor will guide the
leads through a vein and attach them to the specific muscles of your heart. An
X-ray monitoring tool called a fluoroscope may help guide your doctor to your
They’ll then attach the other end of the leads to the pulse
generator. The doctor will make a small incision and place the device in a
pocket of skin on your chest, most often under your left shoulder.
The procedure typically takes between one and three hours.
Afterward, you’ll stay in the hospital for at least 24 hours for recovery and
monitoring. You should feel fully recovered within four to six weeks.
A doctor can also implant an ICD surgically under general
anesthesia. In this case, your hospital recovery time can last up to five days.
What are the risks associated with the procedure?
As with any surgery, an ICD implant procedure may cause
bleeding, pain, and infection at the incision site. It’s also possible to have
an allergic reaction to the medications you receive during the procedure.
More serious problems specific to this procedure are rare.
However, they can include:
- blood clots
- damage to your heart, valves, or arteries
- fluid buildup around the heart
- a heart attack
- a collapsed lung
It’s also possible that your device will occasionally shock
your heart unnecessarily. Although these shocks are brief and not harmful, it’s
likely you’ll feel them. If there’s a problem with the ICD, your
electrophysiologist may need to reprogram it.
What happens after the procedure?
Depending on your situation, recovery can take anywhere from
a few days to a few weeks. You should avoid high-impact activities and heavy
lifting for at least a month after your procedure.
The American Heart
Association discourages driving for at least six months after an ICD
implant procedure. This gives you a chance to assess whether a shock to your
heart will cause you to faint.
What is the long-term outlook?
Having an ICD is a lifelong commitment.
After you recover, your doctor will meet with you to program
your device. You should continue to meet with your doctor about every three to
six months. Be sure to take any prescribed medications and adopt the lifestyle
and diet changes your doctor recommends.
The batteries in the device last for five to seven years.
You’ll need another procedure to replace the batteries. However, this procedure
is slightly less complicated than the first one.
Certain objects can interfere with your device’s
performance, so you’ll need to avoid them. These include security systems and certain
medical equipment, like MRIs and power generators.
You may want to carry a card in your wallet or wear a
medical identification bracelet that states the type of ICD you have. You
should also try to keep cell phones and other mobile devices at least 6 inches
away from your ICD.
Tell your doctor if you’re experiencing any problems with
your device, and call your doctor immediately if your defibrillator delivers a
shock to restart your heart.