Artificial heart valves

introduction

An artificial heart valve is given to patients whose own heart valve is so defective that it can no longer adequately fulfill its function. In order for the heart to pump blood into the body, it is important that the valves open and close properly so that the blood can be transported further. There are basically two different diseases of the valves, called stenosis and insufficiency.

Read more about the topic here: Valvular heart disease

In the Valve stenosis can have a heart valve not opening properly, not enough blood can flow through them, causing the blood to grow jams in the area in front of the flap.

At a insufficiency it is the other way around. The heart valve does not close properly. So it no longer prevents the blood from flowing back. Thus, depending on the severity of the insufficiency, blood can flow back in the direction it came from. This also leads to an increased blood volume in front the flap.

If a heart valve no longer works properly, certain areas of the heart are stressed over a longer period of time. This stress makes the heart unable to pump blood effectively, which results in a Heart failure can develop. This heart failure, too Heart failure called, can start with Medication be treated. However, if medication is no longer sufficient, a artificial heart valve necessary.

How long does an artificial heart valve last?

A common question that patients ask themselves in connection with an artificial heart valve is the question "how long does it last?"

First of all, you have to know that there are different types of artificial heart valves. On the one hand, there are the mechanical heart valves made of metal, on the other hand there are biological valves.

The biological valve, on the other hand, is made of animal material, which often comes from pigs, or as a human valve, which comes from dead donors, also known as "homologous valve replacement". However, the possibility of human donation is very rare at the moment. Most of the biological valves used in humans therefore come from pigs.

In general one can say that the mechanical heart valves last significantly longer than the biological valves. This is a great advantage because the long shelf life means that you can possibly avoid a second heart operation. Mechanical heart valves can last for a few decades. In principle, such a heart valve can even last a lifetime.

In contrast, the shorter shelf life is a disadvantage of the biological valves. Biological heart valves only last about 10-15 years on average. Since, like human tissue, they are also subject to aging processes such as calcification, they are only fully functional for a limited period of time.

In younger patients, aging occurs much more quickly and, as a result, valve function deteriorates. Therefore, one of the selection criteria for the valve is the age of the patient concerned. Older patients (older than 75 years) would probably tend to have a biological heart valve. In a younger patient, on the other hand, a mechanical valve would be more inclined to avoid the risk of a second operation.

What materials is an artificial heart valve made of?

An artificial heart valve consists of particularly durable materials. In laboratory studies, the artificial valves have a durability of 100 to 300 years. In order to be so durable, the material has to be durable on the one hand and be well accepted by the body on the other. Therefore, the various components of the artificial valve are made of carbon and a well-tolerated plastic. These materials also have the advantage that they are very light and therefore do not change the feeling in the chest.

What is the difference to a biological heart valve?

While an artificial heart valve, as the name suggests, consists of artificial material, biological valves come from other living things. Usually the aortic valve of pigs or part of the pericardium of a cattle is used for this. An organ donor flap from a deceased person can also be used.

The biological materials are chemically processed after they have been removed from the donor (human or animal) so that they do not cause any problems in the body. In contrast to artificial heart valves, biological heart valves have a significantly reduced lifespan. The valve material is subject to a normal aging process and has an average shelf life of eight to fifteen years. One advantage over the artificial heart valve is that no blood thinners have to be taken.

The artificial heart valve changes the flow behavior of the blood in such a way that eddies arise, which can easily lead to small blood clots (Thrombi) being able to lead. To counteract this, blood thinners such as Marcumar® must be taken. This is not necessary with biological heart valves. In terms of their mechanical properties, they are similar to the body's own valves in such a way that the flow behavior of the blood does not change.

What is the life expectancy with an artificial heart valve?

The life expectancy with an artificial heart valve is generally increased after the operation. This is mainly due to the fact that the heart can regenerate itself after having had to use increased pumping capacity for a long time due to the broken valve. With targeted lifestyle changes such as a healthy diet and regular physical activity, the life expectancy with an artificial heart valve is comparable to the life expectancy of healthy people. In addition, an artificial heart valve (just like a biological heart valve) improves the quality of life considerably. The heart no longer has to work more and more in a resting state and thus has much more reserves that can be exhausted during physical activity.

In contrast to the biological heart valve, the artificial valve is almost indestructible. The material of the valve itself will last the entire life of the person concerned. Nevertheless, problems such as leaks can occur, in which a new valve may have to be installed. In addition, life expectancy, even with an artificial heart valve, is largely dependent on other diseases such as hypercholesterolemia (high blood lipids) or diabetes. Life expectancy only improves if these are well adjusted with medication.

Which artificial heart valves are there?

An artificial heart valve basically consists of two elements. On the one hand there is a framework that is surrounded by polyester (plastic). This framework forms the transition between the valve and the human heart. There is a metal flap in the frame.

There are different types of flaps. A distinction must be made between three different models.

• There is the artificial heart valve, which consists of a tilting disk. The most prominent representative of this type of valve is the Björk-Shiley prosthesis.
• There are also double-leaf flaps such as the St. Jude Medical.
• The third type of valve is called a ball valve. The best known is the Rigid Edwards ball valve.

Due to their sizes and different mechanical properties, the different valve types each have advantages and disadvantages and are therefore suitable for different patient groups. All three valve types trigger the typical click of the prosthesis, where you can hear the valve leaflet colliding with the valve ring.

OP - insertion of the heart valve

There are now various ways of inserting an artificial heart valve. One option is still a major open heart surgery in which the chest and heart are opened to remove the affected valve and insert the new artificial heart valve. During the large open surgery, the patient is under general anesthesia. The rib cage is opened up by cutting the breastbone in order to get to the heart behind it. Most surgeries are performed on a non-beating heart. The so-called heart-lung machine then takes over the function instead. As soon as the new artificial valve is inserted, the heart is made to beat again.

Another way is the so-called minimally invasive procedure, in which the artificial valve is inserted like a stent over the inguinal arteries into the vascular system and then advanced to the heart. However, this is only possible when the aortic valve is replaced, as it is located at the exit of the heart, which is reached via the arterial vascular system.

The non-invasive method in which the valve is inserted over the inguinal artery is called TAVI. TAVI stands for Transcatheter aortic valve implantation (Engl .: "valve"= Valve). The new artificial aortic valve is inserted via a cardiac catheter. The catheter is advanced to its place of use through the vascular system and then unfolds the artificial heart valve. This takes place when the heart is beating. The new valve presses the old, defective one Fold it against the wall.

What are the risks of an operation?

The operation on artificial heart valves takes place under general anesthesia. This results in a fundamental health risk regardless of the surgical procedure, which also increases with age and the number of previous illnesses (particularly in the cardiovascular system).

In addition, the chest must be opened during the operation to ensure access to the heart. In order to insert the artificial heart valve, the heart has to stand still for a certain time. To do this, the person concerned is connected to a heart-lung machine, which takes over the pumping function of the heart. The heart can then be restrained with medication. Since the use of the heart-lung machine is a very common procedure, the risks here are rather small, even if it involves a very strong intervention in the body's own functions.

Sawing or cutting the chest also puts a lot of strain on the body. There is also the risk of bleeding or infection in the area of ​​the wound and the heart. Infections can also occur later when bacteria attach to the artificial heart valve.

How long are you in the hospital?

The time in the hospital initially consists of the day of admission, which is usually one day from the operation. The operation is followed by two to three days in intensive care to monitor cardiac function. This is followed by a stay in a normal cardiological ward of around two weeks. In most cases, the hospital stay is immediately followed by inpatient rehab, which in turn takes another three to four weeks.

Taken together, a stay in the hospital of six to seven weeks must be assumed.

Rehabilitation after an artificial heart valve?

Rehabilitation after an artificial heart valve usually takes place immediately after the stay in hospital. There are various focal points that are dealt with in the context of rehabilitation. Physical performance should be improved again through physiotherapy, gymnastics and fitness training. There is an educational program on nutrition and medication. Psychological problems such as anxiety, depression and long-lasting pain are also treated.

MRI of the heart

The MRT examination is becoming more and more important within the scope of the diagnostic possibilities. It is therefore particularly important for patients with an artificial heart valve to know whether they are allowed to undergo an MRI examination or whether they should be advised against it. The artificial heart valves used today are mostly made of carbon. From a chemical point of view, carbon is a hydrocarbon. This hydrocarbon is not magnetic, so you could get an MRI scan.

You can find more information on the topic here: MRI with implants (artificial heart valve)

However, older models of an artificial heart valve may contain other materials that could be magnetic. It is therefore important for the patient to look up his or her heart valve passport and to show it to the doctor before each MRI examination so that he can decide whether the examination is even possible.

Furthermore, it is absolutely necessary to check whether the artificial heart valve is firmly seated in its anchorage. The MRI examination creates a magnetic field that creates certain deflection forces. These forces are extremely small, but theoretically minimal displacements can occur if the heart valve is not firmly seated.
Basically, however, one can say that the artificial heart valves installed today are almost all unproblematic for an examination using MRI.

Read more on the topic: MRI of the heart

MRI-compatible artificial heart valve

Almost all available artificial heart valves are MRI compatible. Metallic objects prove to be problematic in the MRI because they heat up in the MRI. However, only the ferromagnetic ones (i.e. those that are influenced by magnetism) are affected, since the MRI works via magnetic forces.

However, the materials used in artificial valves are all non-ferromagnetic. Only those who still have an artificial valve from before 1969 in their heart should find out more, as MRI-critical materials were still used at that time.

Sport despite an artificial heart valve

Sports activity is right and good in almost every situation in life. But especially after the installation of an artificial heart valve, sport plays an even more important role. Sport is one of the most important pillars of therapy for a cardiac patient and should be incorporated into the everyday life of a cardiac patient as regularly as possible. However, it is important not to overwhelm yourself and not to ask too much of your body.

The duration and intensity of the sport is therefore an individual matter. The previous damage to the heart can vary depending on the duration of the existing heart disease. A severely damaged heart then needs significantly longer to recover after a heart valve operation and to achieve the desired performance.

You have to be aware that in the majority of cases with an artificial heart valve you can no longer do competitive sports. However, in the context of heart disease, it is primarily about doing endurance sports and training the heart and body in such a way that performance increases in everyday life. Endurance sports such as walking, cycling or swimming are good for the heart. These should therefore be incorporated into everyday life at regular intervals.

Marcumar®

Another important question that patients with an artificial heart valve often ask themselves is how to take it Blood thinners looks like. Especially in patients who have a mechanical When the heart valve is installed, it is important to take blood thinners. This is where the drug comes first Marcumar® for use.

Marcumar® is administered shortly after the operation. First, it is given in increased doses in order to achieve the necessary concentration. Then have to regular blood tests be done to control the effect of blood thinning. Since a mechanical heart valve is a foreign body in the body and this is also perceived by the body, a mechanical heart valve poses a risk for the development of Thrombi (Blood clots) on its surface. It is therefore particularly important to ensure effective blood thinning with Marcumar® and to take it regularly.

If any operation is planned, the patient must definitely discuss this with his family doctor. Usually there is then a change from Marcumar® to another blood thinner for a certain period of time. Usually this is the so-called unfractionated in heart valve patients Heparin. In contrast to patients with a mechanical heart valve, patients with a biological artificial heart valve do not require lifelong blood thinning.

Bacteria on an artificial heart valve?

The attachment of bacteria to an artificial heart valve is one of the biggest problems in the field of heart valve replacement. Once bacteria have established themselves, endocarditis (inflammation of the inner lining of the heart) occurs and the bacteria can hardly be removed from the valve. There are particularly high risks with infections and procedures in the oral cavity. From there, the bacteria can easily be carried to the heart. It is therefore imperative that those affected inform their dentist that they have an artificial heart valve. So antibiotics can be used preventively.

Is an artificial heart valve ticking?

An artificial heart valve ticks every time the valve closes. However, it is usually only audible in the idle state. The noise is caused by the fact that two metal parts collide when the flap closes. The flap itself hits the fastening ring and thereby triggers a mechanical click. The noise depends on the structure of the heart valve and the anatomical situation of the heart in which it was built. More modern flaps are also particularly quiet.