Pacemaker – indications, procedure, complications. How does a pacemaker work?

Proven content

A pacemaker, or pacemaker, is a device that stimulates the work of the heart, causing it to contract. It also functions as a sinoatrial node. It can be applied temporarily, e.g. to assist the patient during a heart attack or permanently. It is necessary when there are chronic, life-threatening slowdowns of the heart rate.

The pacemaker and the work of the heart

The heart is basically a pump consisting of muscle tissue that is stimulated by electrical currents that normally follow a certain circuit in the heart.

This normal electrical circuit begins in the sinus or sinoatrial (SA) node, which is a small mass of specialized tissue located in the heart’s right atrium (upper chamber). The SA node generates an electrical stimulus of 60 to 100 times per minute (adult) under normal conditions; this electrical impulse from the SA node starts the heartbeat.

The electrical impulse travels from the SA node through the atria to the atrioventricular (AV) node in the lower part of the right atrium. From there, the impulse continues along the electrical conduction path and then through the “His-Purkinje” system to the ventricles (lower ventricles) of the heart. When an electrical stimulus occurs, it causes the muscle to contract and pump blood to the rest of the body. This process of electrical stimulation followed by muscle contraction causes the heart to beat.

A pacemaker may be needed when there are problems with the heart’s electrical conduction system. When the timing of the heart’s electrical stimulation to the heart muscle and the subsequent response of the pumping chambers of the heart are altered, a pacemaker may help.

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Pacemaker – history

Therapy with implanted pacemakers was introduced in 1958. Initially, however, the batteries did not last very long and the patient had to undergo many changes to the device throughout its life. In 1972, pacemakers entered the modern era with the introduction of the first lithium battery.

The first generation pacemakers were only able to stimulate the ventricle at a constant rate without changes. Later, more sophisticated devices were introduced that could detect the patient’s internal ventricular rhythm and deliver stimulation stimulation only when needed. This allowed for a more appropriate physiological response and was dubbed the “on-demand” pacemaker.

Despite this significant technological advance, the internal activity of the atria has not been taken into account. In the late XNUMXs, further advances included the introduction of a second electrode to enable communication between the atria and the ventricles.

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Pacemaker – action

The pacemaker (pacemaker) has three parts: the pulse generator, at least one lead, and an electrode on each lead. A pacemaker signals your heart beating when it is too slow or irregular.

The pulse generator is a small metal case containing electronic circuits with a small computer and a battery to regulate the pulses sent to the heart.

The wire (or wires) is an insulated wire that is connected to the pulse generator at one end and the other end is placed in one of the chambers of the heart. The tube is almost always positioned so that it passes through the chest aorta that leads directly to the heart. The electrode at the end touches the wall of the heart. The cable delivers electrical impulses to the heart. It also senses the electrical activity of the heart and feeds this information back to the Pulse Generator. Pacemaker leads may be placed in the atrium, ventricle, or both, depending on your medical condition.

If the heart rate is slower than the programmed limit, an electrical pulse is sent through the lead to the electrode and the heart beats faster.

When the heart beats faster than the programmed limit, the pacemaker usually monitors the heart rate and will not pace. Modern pacemakers are programmed to operate only on demand, so they do not compete with the natural rhythm of the heart. In general, no electrical pulses will be sent to the heart, unless the natural heart rate falls below its lower limit.

A newer type of pacemaker, called a dual-chamber pacemaker, is now used to treat certain types of heart failure. Sometimes, in heart failure, both chambers of the heart do not work properly. Ventricular dyssynchrony is the common term used to describe this abnormal heart pattern. When this happens, the heart pumps less blood. The Dual Pacemaker stimulates both ventricles simultaneously, increasing the amount of blood pumped by the heart. This type of treatment is called cardiac resynchronization therapy, or CRT.

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Other related medical procedures that may be used to assess how the heart is working include resting and stress electrocardiogram (EKG), Holter, cardiac catheterization, chest X-ray, chest computed tomography (CT), echocardiography, electrophysiology, magnetic resonance imaging (MRI) of the heart .

See these medical procedures for additional information. Keep in mind that although MRI is a very safe procedure, the magnetic fields used by the MRI scanner can interfere with the operation of the pacemaker. Any patient with a pacemaker should always talk to their cardiologist before undergoing an MRI scan.

See: Computed tomography of the heart – an alternative to coronography

Pacemaker – location

The pacemaker is usually placed on the left side of the patient’s body. This is mainly because most people are right-handed and because during the first four to six weeks after implantation, patients must have limited movement near the pacemaker to allow the electrodes to seat. Left-handed patients may have a pacemaker located on the right side. The pacemaker is located in a pocket between the pectoral muscle and the layer of fatty tissue under the collarbone.

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A pacemaker – why is it used?

A pacemaker is implanted to stimulate a faster heart rate when the heart beats too slowly and causes problems that cannot be solved otherwise.

Problems with heart rhythm can cause difficulties because the heart cannot pump enough blood into the body. If the heart rate is too slow, blood is pumped too slowly. If the heart rate is too fast or too irregular, the chambers of the heart cannot fill with enough blood to pump out with each beat. When your body does not get enough blood, symptoms such as tiredness, dizziness, fainting and / or chest pain may occur.

Here are some examples of heart rate problems where a pacemaker may also be inserted:

1. bradycardia – this happens when the sinus node is causing the heart to beat too slowly,
2. sick sinus syndrome (tachy-brady syndrome) – this is characterized by alternating fast and slow heartbeats
3. heart block – this is when the electrical signal is delayed or blocked after it leaves the SA node, there are several types of heart blocks.

There may be other reasons for your doctor to recommend a pacemaker.

Read also: Magnetic resonance imaging of the heart – diagnostics of heart defects and diseases

Pacemakers – what are the risks?

For most people, having a pacemaker has no side effects, although they can be. There is always a slight risk of infection at the site of pacemaker implantation. There may be bleeding or swelling at the pacemaker site, especially if you are taking blood-thinning medications, but some pressure on the wound site usually stops this.

Bruising is common and can spread around the chest and arm. More serious complications are rare but may include a collapsed lung, damage to a blood vessel or nerves in the chest around the pacemaker.

The possible risks of a pacemaker can also include:

1. bleeding from the incision or catheter insertion site
2. damage to the vessel at the site of catheter insertion,
3. infection of the incision or catheter site.

As part of the detail, complications can be acute (during or immediately after surgery) or chronic.

Acute complications after pacemaker implantation:

1. perforation of the heart muscle (heart muscle) – this is a rare but very important complication. Placing the electrode in the chamber may cause it to be punctured by the heart muscle; this mainly happens at the apex of the right ventricle, as the muscle wall is often much thinner here than elsewhere in the ventricle. If the stimulation electrode pierces the apex of the right ventricle, the patient may experience chest pain and shortness of breath associated with pericardial tamponade. To diagnose perforation, imaging tests such as x-rays and echocardiography are needed to help visualize electrode placement.
2. pocket hematoma – this complication occurs due to the accumulation of blood in the pacemaker pockets and coagulation. Studies have shown that this can occur in up to 7,5% of pacemaker implantations and can significantly increase the risk of infection. Patients may experience pain at the pacemaker site or significant swelling. To minimize the occurrence of this complication, a pressure dressing can be used,
3. pneumothorax (air in the pleural space) – mainly caused during venous access using a specific method such as the subclavian puncture technique in which the needle is inserted directly into the vein and can pass into the lungs. To make a complete diagnosis, a chest x-ray is often required, which clearly shows a shadow on the lung.

Chronic complications after pacemaker implantation:

1. pocket erosion – occurs when the pacemaker is recognized by the patient’s immune system as a foreign body, which causes the body to reject the device and attempt to evacuate it. This is evident when it shows up as the device looks like it is running out of the body. Its function is not affected, but the patient may experience severe discomfort. If patients report it, it should be escalated immediately;
2. electrode breakage or insulation failure – this can happen even though the pacing electrodes are designed to withstand pressure and movement exerted by the heart. Each conductor includes a coil covered with polyurethane insulation to provide some degree of flexibility. Pacemaker therapy specialists can identify this complication by interrogating the patient’s device and possibly visualizing it with X-rays. This complication may have a clinically significant effect on device performance and the patient may experience episodes of syncope (syncope),
3. venous thrombosis– may occur several days to several years after pacemaker implantation and may, in rare cases, lead to life-threatening pulmonary embolism. One possible explanation is that the stimulation electrode induces a foreign body type reaction followed by inflammation and fibrosis along the course of the electrode. Some of the most common symptoms include swelling, cyanotic discoloration of the affected arm, pain, and venous prominence.

Patients who are allergic or sensitive to drugs or latex should notify their physician.

In some patients, the need to lie still on the treatment table for the duration of the procedure may cause some discomfort or pain. There may be other risks depending on your specific health condition. You should discuss any concerns you have with your doctor before the procedure.

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Pacemaker – procedure before surgery

Before having a pacemaker, your doctor will explain the procedure to you. Moreover:

1. you will be asked to sign a consent form that gives you consent to perform the procedure. Please read the form carefully and ask questions if anything is unclear.
2. notify your doctor if you are allergic to any medications, iodine, latex or anesthetics (local and general),
3. you will probably need to fast before the procedure,
4. if you are pregnant or suspect that you are pregnant, you should inform your doctor
5. tell your doctor about all medications (prescription and over-the-counter) and herbal or other supplements you are taking.
6. notify your doctor if you suffer from heart valve disease, as an antibiotic may be required before the procedure,
7. tell your doctor if you have suffered from a bleeding disorder in the past or if you are taking anticoagulants (blood thinners), aspirin or other medications that affect blood clotting. You may need to stop some of these medications before surgery.
8. your doctor may do a blood test before surgery to determine how long it takes for your blood to clot. Other blood tests may also be performed.

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Pacemaker – surgery

Pacemaker implantation is relatively safe and simple, and does not cause many serious complications. Anyway, complications related to the procedure of pacemaker implantation concern only a small percentage of patients undergoing the procedure. The implantation of a pacemaker does not require opening the chest, but placing it subcutaneously under the collarbone and passing stimulating electrodes through the intravascular route – most often it is the cephalic or subclavian vein, or the external jugular vein, the internal jugular vein, the femoral vein (at the superior vena cava) – to the heart .

The procedure usually lasts up to about two hours and must be performed with the highest sterility, preferably in an operating room or electrophysiology laboratory. The convalescence after the implantation procedure is not long, the patient should remain under observation of his health and the operation of the implanted pacemaker for a short time. Medical checkups are recommended every few months.

Pacemaker – price

The price of the starter depends on the type of device. Single-chamber pacemaker implantation costs about PLN 7000, a dual-chamber pacemaker is an example cost of about PLN 9000. The prices depend on the type of device and the cost of a specific treatment.