Aortic valve stenosis is the most common form of heart valve defect. It is caused by inflammation or wear and tear processes in the course of life. As a result, the aortic valve cannot open wide enough, allowing less oxygen to enter the body. The heart has to work harder to pump more blood into the body's circulation. This causes it to enlarge. Several symptoms can indicate aortic valve stenosis.
You can find further information and selected aortic valve stenosis specialists here.
Let's first take a look at the anatomy of the heart. The aortic valve forms the transition from the left ventricle to theaorta (Fig. 1).
The blood enriched with oxygen in the lungs is pumped from the left ventricle into the body at high pressure. In a healthy aortic valve, it flows evenly through the valve.
After each ejection(systole), which can be felt as a pulse wave, the aortic valve closes again (diastole).
The aortic valve consists of three delicate sail-shaped pockets (Fig. 2). The opening area of a healthy aortic valve is 3-4 cm². In an adult at rest - depending on body size and weight - approx. 4-5 L/minute flow through the aortic valve.
Fig. 1: Diagram of the human heart and heart valves © bilderzwerg | AdobeStock
When pockets of the aortic valves no longer open fully, this is known as aortic valve stenosis. It is a result of stiffening and calcification of the pockets (Fig 3). The left ventricle has to generate increasingly higher pressure in order to pump the same amount of blood through the narrowing.
Aortic valve stenosis is considered severe if the remaining opening area is less than 1 cm². The smaller the remaining opening area, the higher the blood flow velocity and the pressure difference before and after the aortic valve (mean pressure gradient).
The heart initially reacts to the pressure load by strengthening the heart muscle (hypertrophy). If the aortic valve stenosis persists for a long time, an enlargement of the left ventricle (dilatation) may occur in addition to the hypertrophy.
Fig. 2: Aortic valve with the 3 delicate pockets, in an open state (image by Prof. Dr. med. Alexander Albert during an aortic valve reconstruction according to DAVID)
Fig. 3: Stenotic aortic valve with 3 pockets that have become stiff due to calcification and thickening and no longer open properly.
Various causes can be responsible for aortic valve stenosis. Firstly, a distinction is made between congenital aortic valve stenosis and aortic valve stenosis acquired in the course of life. Only ten percent of all aortic valve stenoses already exist at birth. In most cases, the heart disease only develops in the course of life.
Aortic valve stenosis occurs most frequently in older people after the age of 60. Various factors promote age-related wear and tear processes. These lead to connective tissueremodeling and calcification of the valve pockets. Favors a faster progression of this process, which is not fully understood:
Aortic valve stenosis develops gradually and usually remains asymptomatic in the first phase. It is therefore not uncommon for aortic valve stenosis to go unnoticed for years and only become apparent during routine examinations.
In the early stages, symptoms only occur during physical exertion. The heart is no longer able to pump enough blood through the stenosis during strenuous exertion. If too little blood reaches the brain, this manifests itself as dizziness and light-headedness. This can even lead to a brief loss of consciousness (syncope).
The increasing thickening of the heart muscle leads to muscular and connective tissue remodeling of the heart (negative remodeling). Once the muscle reaches a certain thickness, it can no longer be adequately supplied with oxygen. Similar to coronary heart disease, this leads to
The heart also becomes stiffer and less flexible (reduced compliance).
As a result, the atrium has to exert ever-increasing pressure to stretch and fill the left ventricle. This leads to pathological enlargement (dilatation) as well as muscular and connective tissue remodeling of the atrium.
This causes cardiac arrhythmia - in particular atrial fibrillation. The remodeling of the entire heart also increases the risk of ventricular (malignant) arrhythmias. These in turn can cause loss of consciousness.
In the later stages, the entire heart enlarges and cardiac output decreases. The blood then backs up into the lungs, leading to shortness of breath and even pulmonary edema. Shortness of breath as a symptom of heart failure is associated with a very poor prognosis if left untreated.
Aortic valve stenosis produces a characteristic heart murmur. Doctors can hear the murmur during a routine examination with a stethoscope and make a suspected diagnosis.
The diagnosis is confirmed by an ultrasound examination of the heart(echocardiography).
The severity of aortic valve stenosis is classified as follows:
| Aortic valve stenosis | Mild stenosis | Moderate stenosis | Severe stenosis | |
| Max. Flow velocity, m/sec | <2,5 | 2,5-3 | 3-4 | >4 |
| Mean pressure gradient, mmHG | No gradient | <20 | 20-40 | >40 |
| Opening area of the aortic valve | 3-4 cm² | >1,5 | 1-1,5 | <1 |
Cardiac function is also important for the prognosis (ejection fraction of the left heart - ejection fraction (EF)):
The standard treatment for aortic valve stenosis is surgery.
Heart valve insufficiencies (leaks) can often be reconstructed. In the case of stenosis, the leaflets or pockets are typically destroyed by inflammation and degeneration. They no longer open adequately.
Accordingly, replacement of the heart valve is always necessary in the case of (acquired) aortic valve stenosis.
A heart valve replacement is necessary in cases of severe aortic valve stenosis with additional typical symptoms. These can also be symptoms that only occur during exercise.
Sometimes the patient has few or no symptoms, but the heart already shows significant damage as a result of the aortic valve stenosis (EF <50%). In this case, surgery is also necessary.
Sometimes the severity of the aortic valve stenosis is not easy to determine. This is the case, for example, if the heart function is clearly restricted. Special examinations by a cardiologist are then necessary to determine the severity of the aortic valve stenosis.
Classically, aortic valve replacement is performed by open heart surgery.
The heart is accessed via a longitudinal opening in the sternum [Fig. 6, sternotomy]. The patient is connected to a heart-lung machine. This takes over the functions of the heart and lungs during the operation. In this way, the heart is "immobilized" and the surgeon can work on it safely.
The surgeon then removes the old, diseased components of the aortic valve and then sews in a prosthesis.
The advantage of open heart surgery is that the surgeon has a direct and clear view of the aortic valve.
The same operation can also be performed minimally invasively in specialized centers. This means either only partial transection of the sternum [Fig. 7, partial sternotomy], or a lateral approach by spreading the ribs.
Nowadays, replacement of the aortic valve is increasingly performed using minimally invasive techniques, but without a heart-lung machine. The so-called catheter-based procedure(TAVI) is of great importance here. It is not a surgical procedure in the classical sense.
The new heart valve prosthesis is implanted via the groin [Fig. 9 transfemoral TAVI] or between the ribs through the apex of the heart [Fig. 10 transapical TAVI].
Aortic valve replacement using transfemoral TAVI can be performed with the patient awake.
TAVI is currently used for
are recommended.
There is still too little experience available for younger patients. In addition, the physician will consider various technical aspects that speak for or against TAVI.
Arguments in favor of TAVI:
Certain anatomical characteristicsspeak against TAVI
TAVI prostheses are biological prostheses. For this reason, a mechanical prosthesis or the Ross operation is used in patients under 50 to 60 years of age.
In non-TAVI procedures, the patient can choose between biological and mechanical prostheses (see Fig. 4 and 5). TAVI prostheses are always biological prostheses. Biological prostheses are made from the heart valves or pericardium of pigs or cattle . The material is modified in such a way that it is accepted by the body's immune system and accepted very well.
The disadvantage of these prostheses is that they wear out very quickly, especially in younger patients. They are ideal for patients over the age of 70, where they are expected to last over 20 years.
However, nowadays there are other options in the event of wear and tear and the occurrence of a new aortic valve stenosis. The so-called valve-in-valve procedure can be used as a TAVI without the need for a second operation.
With the prospect of avoiding a repeat operation, biological prostheses are now even recommended for patients between the ages of 50 and 60. With each new TAVI, however, the opening area becomes smaller and smaller. As a result, this valve-in-valve procedure can usually only be performed once.
Fig. 4: Biological heart valve made from bovine material (courtesy of Edwards)
Fig. 5: Mechanical heart valve (courtesy of the Medtronic company)
Mechanical prostheses are recommended for patients < 50 to 65 years of age. These are made of robust carbon-containing material and theoretically last forever. However, blood clots easily form on this artificial surface, which can lead to blockages in the prosthesis and strokes.
Patients must therefore take blood-thinning medication - usually Marcumar or warfarin - for the rest of their lives. The problem with Marcumar therapy is that even minor injuries can lead to severe bleeding. Brain haemorrhages are particularly feared here.
The risk of serious bleeding is not so high at 1-2% per year. However, the risk accumulates over the decades, particularly in younger patients. This Marcumar therapy can lead to a significant reduction in quality of life, particularly for patients who play sport or have physically demanding jobs.
Mechanical prostheses can also be inserted minimally invasively via the ribs (antero-lateral minithoracotomy) with the appropriate experience. Understandably, this is never done as a TAVI because they cannot be folded.
For younger patients, this means that neither the biological nor the mechanical prosthesis is a really good solution.
The Ross operation is an alternative. In this procedure, the aortic valve is replaced by the body's own heart valve, the pulmonary valve. This is located between the right heart and the pulmonary circulation. In this low-pressure circulation, it is exposed to significantly less blood pressure and stress than the aortic valve and is therefore somewhat more delicate. Otherwise, it has the same anatomical structure as the aortic valve.
It is dissected out during the operation and sutured in place of the diseased aortic valve. The pulmonary valve (pulmonary autograft) has all the properties of a natural heart valve. It therefore does not require blood thinning and is not subject to wear and tear. It is therefore a true biological prosthesis.
The operation is also performed on children with aortic valve stenosis, where it even grows with the child.
Where the pulmonary valve has been removed, a so-called homograft is inserted. This comes from a deceased person and is provided by specialized homograft banks before the operation.
This homograft is exposed to less stress in the pulmonary flow area. They therefore last much longer than if they were inserted directly into the position of the aortic valve.
The Ross operation is quite complicated and is only offered by a few surgeons with years of experience.
The complete sternotomy is the standard procedure for cases that are not suitable for TAVI. These cases are therefore younger patients without a significantly increased surgical risk.
In most cases, a minimally invasive operation as an anterolateral mini-thoracotomy would also be an alternative for these patients (see below).
Fig. 6: Classic sternotomy, image source [https://adultct.surgery.ucsf.edu/conditions--procedures/minimally-invasive-aortic-valve-surgery.aspx]: "Minimally-invasive Cardiac Surgery" by Tobias Deuse, M.D.
For which patients is the procedure suitable?
Many surgeons no longer perform this procedure. Because the sternum is opened, there is also a risk of instability and problems in this area.
As a truly minimally invasive alternative to surgery via a sternotomy, surgeons prefer the antero-lateral mini-thoracotomy without opening the sternum (see below).
Fig. 7: The partial stenotomy, image source [https://adultct.surgery.ucsf.edu/conditions--procedures/minimally-invasive-aortic-valve-surgery.aspx]: "Minimally-invasive Cardiac Surgery" by Tobias Deuse, M.D.
The anterolateral mini-thoracotomy involves opening the chest near the sternum between the second and third ribs.
During MIS surgery, the surgeon reaches the heart via a small incision between the ribs. The sternum is not opened in the process.
The heart-lung machine is connected via the femoral vessels (leg arteries and veins) through a puncture (without an incision).
For which patients is the procedure suitable?
In the hands of experienced surgeons, almost all aortic valve operations can be performed via this access. It is used when a TAVI procedure is not an option (see below).
Fig. 8: The anterolateral mini-thoracotomy, image source [https://adultct.surgery.ucsf.edu/conditions--procedures/minimally-invasive-aortic-valve-surgery.aspx]: "Minimally-invasive Cardiac Surgery" by Tobias Deuse, M.D.
Transfemoral TAVI
During TAVI surgery, a biological aortic valve is attached to a catheter tip. The surgeon pushes it up to the heart and fixes it in the aortic valve position by stretching it.
The TAVI procedure was developed for the following patients
The procedure is performed in a so-called hybrid operating theater. It combines the possibilities of a cardiac catheterization laboratory (mobile X-ray system) and the equipment of an operating theatre.
With this TAVI procedure, it is not necessary to cut through the sternum or use the heart-lung machine. The catheter is usually advanced into the heart via the inguinal artery (transfemoral).
Transfemoral TAVI is now the gold standard for the treatment of aortic valve stenosis in
The procedure can be performed under anesthesia or with the patient awake.
Aortic valve replacement using a catheter © Henrie | AdobeStock
Transapical TAVI
Transapical means that the valve is inserted via the apex of the heart. This method is an option if the inguinal arteries are too small or the main arteries are severely calcified.
An incision a few centimeters long is made on the left half of the chest wall below the nipple. The catheter is then inserted directly over the apex of the heart.
A folded biological heart valve prosthesis is advanced via the catheter to the site of the diseased aortic valve and expanded. The diseased heart valve is then pressed into the wall of the aorta and replaced.
This procedure is now standard for aortic valve replacement. In certain cases, it is also possible to replace the mitral valve in this way (TMVI).
Transapical aortic valve replacement is possible for all patients who are older or have an increased surgical risk.
Transfemoral TAVI is even less invasive than transapical TAVI. It can also be performed with the patient awake. This is why transfemoral TAVI is preferred nowadays. Exceptions are patients with
In the presence of coronary heart disease, a combination of TAVI and single coronary bypass on the anterior wall of the heart is also performed.
It is also used as a hybrid procedure with subsequent PCI (stenting) of the side and/or back wall of the heart.
Ross operation
The Ross operation is suitable for
Certain anatomical criteria must be met. These can usually be clarified preoperatively using appropriate examinations such as CT or MRI. In particular, the sizes of the pulmonary and aortic valves should not differ too much from each other.
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