A pacemaker, in fact, is the entire pacing system. The pacing system consists of a pacemaker, a pacing electrode lead and a programmable controller. The pacemaker and the pacing electrode lead are implanted in the body.
The pacemaker consists of a circuit and a battery mounted in a metal box. The pacemaker sends small electrical pulses to the heart when needed.
The pacing electrode leads consist of insulated wires that transmit tiny electrical impulses to the heart to stimulate it to beat.
Programmable pacemakers are usually placed in hospitals or clinics. A special computer, the programmer, allows nurses and physicians to observe the operating status of the pacemaker and to adjust the pacemaker settings when needed.
These three parts of the pacing system work together to help improve the symptoms of bradycardia. The pacing system causes the heart to beat faster to meet the body’s need for oxygen.
By increasing the heart rate, the symptoms of bradycardia are usually relieved or eliminated, which means the patient can have increased vitality and less shortness of breath. Generally speaking, pacing therapy is a treatment for bradycardia and does not eradicate the cause of the bradycardia. Therefore, the pacing system does not prevent other heart diseases (e.g. coronary artery disease, etc.) or heart failure, etc.
To date, pacemakers are the only means of treating bradycardia. This great technology has benefited more than 2 million people in the last 50 years. Thanks to pacemakers, patients with bradycardia can look forward to a normal life.
Part I: Pacemakers
The pacemaker is the “power” part of the entire pacing system, with an electronic part that determines when a small electrical energy, known as a pacing pulse, is sent. The pacemaker consists of a titanium housing with internal circuitry and a battery.
The pacing battery provides the energy needed for pacing (i.e., the tiny electrical pulses). This tiny, sealed lithium battery usually works for several years. When the battery is depleted, the entire pacemaker needs to be replaced.
Circuitry The circuitry of the pacemaker is like a microcomputer. The circuit converts the battery energy into tiny electrical pulses that are not felt by the patient, and the circuit controls the timing and amount of electrical energy released.
This part is located at the upper end of the metal housing of the pacemaker and is a transparent plastic part. The connection port is where the pacing electrode leads are connected to the pacemaker.
History
Since 1950, when the world’s first pacemaker was implanted, approximately 2 million people worldwide have benefited from this great invention, and since 1985, a large number of new technologies have brought great benefits to patients. For example, new technologies that automatically adjust the pacemaker to the patient’s physiological needs in response to the patient’s activity (e.g., exercise) have greatly improved the patient’s quality of life.
Today, through the use of microelectronics and smoother, lighter metals, pacemakers are becoming smaller, lighter, and more streamlined than ever before.
Pacemakers are multifunctional and their settings can be adjusted in the clinic or doctor’s office during follow-up visits to allow for more targeted treatment plans.
Part II: Pacemaker leads
The pacing electrode lead is a piece of insulated wire that is connected to the pacemaker. They are very flexible in order to adapt to the bending and twisting of the body’s movements, as well as to the activity of the heart itself.
The pacing lead has two main functions.
1. Transmitting the tiny electrical impulses sent from the pacemaker to the heart.
2. To transmit the electrical activity of the heart back to the pacemaker.
The pacing electrode lead consists of four parts.
1. connecting pin: the part of the electrode lead that is inserted into the pacemaker connection port
2. Electrode lead body: the insulated metal wire that transmits electrical energy from the pacemaker to the heart.
3. Fixation structure: The structure near the electrode lead head that fixes the electrode lead to the heart muscle.
4. Electrode lead head: At least one electrode lead head is located at the tip of the electrode lead. The electrode lead head transmits the electrical energy from the pacemaker to the heart tissue and at the same time transmits information about the electrical activity of the heart back to the pacemaker.
Where is the pacemaker placed: inside or outside the heart? For most adults, the electrode lead is inserted through a vein and guided to the right atrium or right ventricle. These leads are called “intracardiac leads” or “transvenous leads” (because they are inserted through a vein).
Sometimes the lead is attached to the outer wall of the heart, and this type of lead is called an “extracardiac lead”. Extracardiac leads are usually used in children because their bodies are still growing. An extracardiac lead may also be used if another procedure is being performed and the lead can be easily placed in the outer wall of the heart at that time.
Drug therapy when the electrode lead is attached to the heart tissue.
Whether an extracardiac lead or an intracardiac lead is used, an inflammatory reaction will occur where the lead is attached to the heart tissue. Just as your skin becomes red and swollen and crusty when you cut it, the same reaction occurs when the lead is placed into the heart. Medtronic’s CapSure Pacemaker leads reduce this inflammation by applying medication to the tip of the lead.
The drug applied to the tip of the electrode lead is a hormone called a steroid. The amount is very small (less than 1 mg) and is usually applied to the tip of the lead. By slowly releasing the drug while the lead is fixed to the heart, the potential for crusting between the lead end and the heart tissue is minimized. By reducing the amount of crusted tissue, the pacing lead works more efficiently.
Depending on the treatment needs, one or several leads may need to be implanted.
Part III: The Programmer
A programmer is a special computer used to monitor and adjust Medtronic pacemakers.
During the patient’s hospitalization or follow-up, the physician or nurse places a magnetic bar (or programmable electrode lead) over the pacemaker, which allows the programmer to
Receive information from your pacemaker. The information collected from the pacemaker shows how your pacemaker and your heart are working. Based on this information, decide whether a change in the treatment plan is needed.
Sending commands to the pacemaker. When a change in treatment plan is needed, the doctor or nurse can send the command to the pacemaker – without any surgery.
The pacemaker is part of a pacing system that can help improve the condition of your heart. A pacing system consists of a pacemaker, a pacer, and one or more pacing electrode leads.