Devices that are used to manage heart rhythm problems are also referred to as CRM (cardiac rhythm management) devices, and include pacemakers and implantable cardioverter-defibrillators (ICDs). Pacemakers are among the most common types of cardiac devices and are used to regulate the heartbeat of patients diagnosed with arrhythmia. If your doctor says you may need one, you likely have questions and concerns about your diagnosis and treatment. However, once you understand how a pacemaker can help alleviate symptoms associated with your cardiac condition, you may feel more comfortable about the procedure and your treatment plan going forward.
The Heart’s Electrical System
The heart rhythm is actually controlled by the heart’s electrical system, which generates the signals that cause the muscle to contract. The normal heartbeat starts in a structure called the Sinus Node, located at the top of the right atrium. The sinus nodal cells “fire” or generate the electrical “spark” that starts each heartbeat. That electrical signal spreads across the top chambers and stimulates the atria to contract. The electrical signal of the atria then passes through the electrical connection between the top and bottom chambers. This connection is called the atrioventricular (AV) Node. The AV node allows the top and bottom chambers to work together and maintains efficient pumping of the blood.
Patients with electrical disease of the heart can develop excessively slow heartbeats (bradycardia). One condition, known as “Sick Sinus Syndrome,” is due to gradual failure of the sinus node. It leads to progressive slowing of the normal heart rate to the point where the heart does not pump fast enough to meet the body’s needs. A diminished cardiac output leads to symptoms of fatigue, weakness, lightheadedness, shortness of breath, and inability to exercise. Another condition can occur if the AV node malfunctions. This is known as “AV Block,” and it causes failure of the electrical signal to pass from the atria to the ventricles. This can lead to dramatic slowing of the heart rate. If severe enough, the heart can stop, leading to symptoms such as fainting and even death.
The History of Pacemakers
The complexities of the heart’s electrical system weren’t uncovered until 1924, when William Einthoven, a Dutch physician, was awarded the Nobel Prize in Medicine for his publications regarding the electrocardiogram (ECG or EKG). His work showed that each time the heart beats the heart muscle emits low level electrical currents that can be picked up from the skin. The ECG provides doctors with a visual map of how the patient’s heart is functioning, and allows physicians to make an accurate diagnosis of heart rhythm disturbances.
Although doctors knew that some patients suffered with severe symptoms from bradycardia, they had no way of helping those patients until the 1930s, when scientists found that a small electrical stimulation from a generator delivered to the heart through a wire could cause the heart muscle to contract. A steady series of stimuli could restore a normal heart rate, which is the basis for how pacemakers work. In the early 1950s, large tabletop external pacemakers were developed and could keep patients with severe bradycardia alive. However, these were not practical long-term solutions.
By the late 1950s a number of primitive implantable pacemakers had been inserted in patients, demonstrating the feasibility of a self-contained device that was capable of delivering small electrical stimuli to keep the heart beating at a normal rate. By 1970 battery technology had improved dramatically, and this led the way to the development of modern pacemakers as they are commonly known and used today.
The Relationship Between Heart Disease and Pacemakers
Heart disease is extremely prevalent today and is one of the leading causes of death among Americans. Heart rhythm problems affect its ability to pump blood sufficiently and can cause significant symptoms and adverse cardiac effects. A normal human heart rate is between 60 and 80 beats per minute (bpm) at rest. When a person exercises, the heart rate should increase. We can calculate the predicted maximal heart rate by subtracting a person’s age from the number 220. Thus, a 50 year old person should be able to reach a heart rate of 170 beats per minute with maximal effort. Bradycardia can affect the heart rate at rest, and if the resting heart rate falls to very low numbers (generally below 50 beats per minute) patients may start to have symptoms. Another manifestation of significant bradycardia occurs if the heart rate does not increase appropriately with exercise. This condition, known as “chronotropic incompetence,” can be diagnosed, for example, in a person who runs out of steam easily with exercise, yet the heart rate never gets above 90 bpm. Keep in mind that highly conditioned athletes can have very slow resting heart rates, but that would be normal for them. A patient with an excessively slow heart rate, particularly if it causes symptoms that affect their quality of life, may require the use of a pacemaker to help restore and regulate a normal heartbeat. If you happen to need a pacemaker, you will be in good company. Approximately 600,000 new pacemakers are implanted each year!
How Are Pacemakers Implanted?
Today’s pacemaker is a small device that is roughly the size of a silver dollar, though perhaps twice as thick. Inside the pacemaker can (known as the “pulse generator”) is the battery, the computer circuitry, and a communication circuit that allows us to talk to the device and change its behavior. In addition to the generator, the system includes wires or leads that connect the pacemaker to the heart. Generally two leads are used, though some systems have only one lead and some have three. The generator is surgically implanted below the skin and fat of the upper chest wall, generally on top of the muscle (so it won’t interfere with your ability to exercise). The leads are inserted into a vein and are advanced into the chambers of your heart using x-ray guidance. The leads detect the electrical activity of your heart, the computer circuit analyzes your heart’s needs on a beat-to-beat basis, and small electrical signals are delivered to the heart through the leads as needed to correct any slow heart beat problems. The procedure is considered to be “minor” surgery and should take about an hour to complete. It is done with a local anesthetic, and generally with some sedation. Most people stay overnight, though some may be discharged the same day. The pacemaker will work tirelessly for 8-10 years to keep the heart beating properly, and generally the patient won’t even know it’s working. After the battery wears down, the device is replaced with a new one, while the leads should last the rest of your life.
Ideally, your pacemaker will be inserted by a cardiac rhythm specialist or Cardiac Electrophysiologist. However, in some communities pacemakers may be implanted by cardiologists or surgeons, depending on who is available and experienced in the procedure. Regardless of who implants the device, make sure you have a comprehensive consultation ahead of time to discuss the risks, benefits, and alternatives to the surgery.
Other Concerns: The Cost of Pacemakers
Cardiac devices such as pacemakers are expensive, and they need to be implanted in a hospital, so in addition to the cost of the device there are hospital costs, including the operating room and sometimes anesthesia costs. The pacemaker will have to be checked every 3-6 months after it is implanted, so there are medical charges associated with the routine follow-up care. Pacemakers are covered by all health insurance plans, though you may be responsible for a percentage of the total cost. Check with your insurance carrier if you have any questions.
For patients not covered by insurance, the cost of pacemaker surgery can be quite high, so it’s best to discuss financial concerns with the business office associated with your medical provider. However, any patient who needs a pacemaker is likely to be older, and often has had other medical problems before, so the vast majority of those patients already have some form of health insurance.