Pacemaker & ICD
Pacemaker & ICD Implantation
You may have heard of two little devices that doctors use to help treat heart problems: pacemakers and ICDs (implantable cardioverter defibrillator).
What Is a Pacemaker?
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 out of rhythm. When that happens, it sends out electrical pulses to keep your heart at a steady rhythm and rate.
Pacemaker Types
Depending on your condition, you might have one of the following types of pacemakers.
- Single chamber pacemaker. This type usually carries electrical impulses to the right ventricle of your heart.
- Dual chamber pacemaker. This type carries electrical impulses to the right ventricle and the right atrium of your heart to help control the timing of contractions between the two chambers.
- Biventricular pacemaker. Biventricular pacing also called cardiac resynchronization therapy, is for people who have heart failure and heartbeat problems. This type of pacemaker stimulates both of the lower heart chambers (the right and left ventricles) to make the heart beat more efficiently.
Why it's done
A pacemaker is implanted to help control your heartbeat. Your doctor may recommend a temporary pacemaker when you have a slow heartbeat (bradycardia) after a heart attack, surgery or medication overdose but your heartbeat is otherwise expected to recover. A pacemaker may be implanted permanently to correct a chronic slow or irregular heartbeat or to help treat heart failure.
How your heart beats
The heart is a muscular, fist-sized pump with four chambers, two on the left side and two on the right. The upper chambers (right and left atria) and the lower chambers (right and left ventricles) work with your heart’s electrical system to keep your heart beating at an appropriate rate — usually 60 to 100 beats a minute for adults at rest.
Your heart’s electrical system controls your heartbeat, beginning in a group of cells at the top of the heart (sinus node) and spreading to the bottom, causing it to contract and pump blood. Aging, heart muscle damage from a heart attack, some medications and certain genetic conditions can cause an irregular heart rhythm.
What a pacemaker does
Pacemakers work only when needed. If your heartbeat is too slow (bradycardia), the pacemaker sends electrical signals to your heart to correct the beat.
Some newer pacemakers also have sensors that detect body motion or breathing rate and signal the devices to increase heart rate during exercise, as needed.
A pacemaker has two parts:
- Pulse generator. This small metal container houses a battery and the electrical circuitry that controls the rate of electrical pulses sent to the heart.
- Leads (electrodes). One to three flexible, insulated wires are each placed in one or more chambers of the heart and deliver the electrical pulses to adjust the heart rate. However, some newer pacemakers don’t require leads. These devices, called leadless pacemakers, are implanted directly into the heart muscle.
What Is a ICD?
An implantable cardioverter-defibrillator (ICD) is a small battery-powered device placed in the chest to detect and stop irregular heartbeats (arrhythmias). An ICD continuously monitors the heartbeat and delivers electric shocks, when needed, to restore a regular heart rhythm.
You might need an ICD if you have a dangerously fast heartbeat that keeps your heart from supplying enough blood to the rest of your body (such as ventricular tachycardia or ventricular fibrillation) or if you are at high risk of such a heart rhythm problem (arrhythmia), usually because of a weak heart muscle.
An ICD differs from a pacemaker — an implantable device that can prevent dangerously slow heartbeats.
Types
An ICD is a type of cardiac therapy device. There are two basic types:
A traditional ICD is implanted in the chest, and the wires (leads) attach to the heart. The implant procedure requires invasive surgery.
A subcutaneous ICD (S-ICD) is another option that’s implanted under the skin at the side of the chest below the armpit. It’s attached to an electrode that runs along the breastbone. An S-ICD is larger than a traditional ICD but doesn’t attach to the heart.
Why it's done
An ICD constantly monitors for irregular heartbeats and instantly tries to correct them. It helps when the heart stops beating effectively (cardiac arrest).
Your health care provider may recommend an ICD if you’ve had signs or symptoms of a certain type of irregular heart rhythm called sustained ventricular tachycardia, including fainting. An ICD might also be recommended if you survived a cardiac arrest. Other reasons you may benefit from an ICD are:
- A history of coronary artery disease and heart attack that has weakened the heart
- An enlarged heart muscle
- A genetic heart condition that increases the risk of dangerously fast heart rhythms, such as some types of long QT syndrome
- Other rare conditions that may affect the heartbeat
A health care provider may recommend an S-ICD if there are structural defects in the heart that prevent attaching wires to the heart through the blood vessels.