What is a pacemaker?
A pacemaker is an artificial device that electrically stimulates the heart's muscle to cause it to contract to initiate a heartbeat. It is a small, lightweight electrical device surgically placed inside in the upper chest area. A pacemaker will keep your heart rate from going below a pre-programmed rate. That will help ensure that enough oxygen and nourishment get to your body's cells. A pacemaker may be temporary or permanent, depending on the patient's condition.
An artificial pacemaker system has two parts: a generator and wire (leads). The pacemaker generator is a small lithium battery-powered unit. It produces the electrical impulses that start your heartbeat. The generator is implanted under your skin through a small incision. A generator is connected to your heart through tiny wires that are implanted at the same time. The impulses flow through these leads to your heart and are timed to flow at regular intervals just as impulses from your heart's natural pacemaker would.
A pacemaker senses every heartbeat the patient has and only paces the heart when the patient's heart rate falls below a pre-set limit, this is called a demand pacemaker. A demand pacemaker has a sensing device that shuts it off if the heart rate is above a certain rate. When the heart is beating slower than the pacemaker rate, the sensing device turns the pacemaker on again. Patients are usually completely unaware of when the pacemaker is pacing their heart.
When is a pacemaker indicated?
A pacemaker is a treatment for a dangerously slow heart rate or arrhythmia. Frequently, pacemakers are necessary following a heart attack or cardiac surgery. Without treatment, a slow or irregular heart rate can lead to weakness, confusion, dizziness, fainting, shortness of breath and even death. Slow heart rates can be the result of metabolic abnormalities or occur as a result of blocked arteries to the heart's conduction system. Slow heart rates can also be a side effect of certain medications.
The sinoatrial node may speed up or slow down the rate at which it sends its electrical impulse. If the sinoatrial node slows down the rate, the heart chambers do not contract often enough to supply the proper amount of blood to your body. This type of arrhythmia is called bradycardia. If the sinoatrial node speeds up the rate, the heart chambers do not have enough time to fill with enough blood to adequately perfuse the body's tissues. This type of arrhythmia is called tachycardia.
Problems may also occur with the electrical pathway between the upper heart (atria) and the lower heart (ventricles). The electrical signals sent out by the sino-atrial node may be delayed in the atrioventricular node (AV node) or may fail to reach the ventricles all together. This arrhythmia is called heart block. Heart block may also cause poor timing with the atria and the ventricles. Doctors call this condition asynchrony. As a result, the ventricles will not fill with enough blood before contracting.
What happens during implantation of a pacemaker?
Fortunately, having a pacemaker implanted is only a minor surgical procedure. This is not an open-heart surgery. The procedure is performed with mild sedation and a local anesthetic. Patients are not put to sleep. An area of skin in the upper chest area is shaved, scrubbed, and then cleaned with a special antiseptic. You are given injections of numbing medicine in that area. The doctor may touch the area and ask you when you start to lose sensation in your upper chest.
A small, approximately 2-inch incision is made parallel to and just below the collarbone. A thin flexible wire (called the lead) is inserted into a vein that lies just under the collarbone. The doctor gently advances the lead through that vein under fluoroscopic guidance into the heart. The fluoroscope may be thought of as a kind of moving X-ray picture. Once the lead enters the heart, the doctor attaches it to the tissue inside the heart. At this point, the doctor will test the lead to see if it is in a suitable place for pacing. The testing is not painful. After the lead test, your doctor may decide to move the lead and run the test again. Repositioning and retesting a pacing lead several times is not unusual in pacemaker surgery.
The other end of the pacer wires are connected to a "generator" that is implanted under the skin beneath the collarbone. This generator is about half an inch deep and one and a half inches wide. The skin is then sutured closed and the patient leaves the hospital later that same day or the following day. Pain around the incision is mild and transient and usually responds to Tylenol. It is possible to feel the pacer generator under the skin and a slight deformity of the skin can be visually noticed.
What are possible complications?
Any surgical procedure includes the possibility of complications. The most typical complications for pacemaker implantation are not life threatening, but may require a longer hospital stay or a repeated operation. The most common complications include bleeding, infection, lead dislodgement, and problems with the pacemaker working properly. Ask your doctor about potential complications before your surgery.
Do pacemaker batteries wear out?
The pacemaker contains batteries that will wear down over time, just like any electronic device. The batteries wear down, your pacemaker will slow down, but it will not stop right away. Most batteries last at least 5 years. Using a special analyzer, the doctor can detect the first warning that the batteries are running down. This can be done before you detect any changes yourself. A sudden major slowing down of your heart rate, which you may detect, indicates a more serious problem. If that occurs, call your doctor.
Patient instructions after implantation.
1. SYMPTOMS TO REPORT TO YOUR DOCTOR
3. SPECIAL INSTRUCTIONS
4. THINGS TO AVOID *Keep the following potential sources of strong electrical or magnetic fields at least 30 cm (12 inches) away from your Pacemaker.
Where is the test performed?
In the cardiac catheterization lab at EvergreenHealth.
How long does this test take?
Typically this procedure takes 1-2 hours to perform and patients go home either the same day or the next day.