Function of the Aortic Valve
The aortic valve lies between the left ventricle and the main artery (aorta). It ensures that the blood from the heart, which is rich in oxygen, can flow outwards but not back again. The aortic valve is known as a seminlunar valve as it consists of three cusps of half-moon-like shape.
These cusps are attached to a ring made of connective tissue, which is part of the scaffolding of the heart. The blood leaving the heart presses the cusps apart. In the relaxation phase of the left ventricle they move back close together, preventing backflow of the blood.
Diseases of the Aortic Valve
Aortic Valve Insufficiency
If the cusps of the aortic valve no longer close properly in the relaxation phase, the valve “leaks”. Some of the blood that is being pumped into the body then flows back into the left ventricle. This is known as valve insufficiency or regurgitation.
Aortic Valve Stenosis
When the aortic valve cusps no longer open sufficiently to allow the blood through, an aortic valve stenosis is present; this is the most common heart valve defect. The aortic valve stenosis is usually an acquired condition, mostly caused by processes of wear, such as calicification, thickening and stiffening of the tissue in advanced age. Rheumatic fever or inflammation of the inner layer of the heart (endocarditis) can also lead to scarring of the aortic valve and cause an aortic valve stenosis. Between three and five percent of individuals over 75 years of age have an aortic valve stenosis. Congenital aortic valve stenosis is much rarer and leads to symptoms at a younger age.
Symptoms and Diagnosis
Patients with mild forms of aortic valve stenosis often have no symptoms. More severe forms cause breathlessness, pain or a feeling of tightness in the chest. Patients often also suffer from dizziness or short loss of consciousness, since the brain briefly receives too little oxygen.
The first important method of diagnosing a heart valve disease is echocardiography (ultrasound examination) of the heart. Next, an ECG is performed and, if necessary, also a chest X-ray. To prepare for an operation on an aortic valve stenosis, an exact, invasive diagnosis is usually conducted in the heart catheterization laboratory.
The first-line method of diagnosing a heart valve disease is echocardiography (ultrasound examination). In addition, an ECG is performed and, if necessary, a chest X-ray. To prepare for the operation to treat an aortic valve stenosis, a heart catheter examination is usually conducted.
Treatment: Aortic Valve Replacement
There is no pharmacological treatment for aortic valve stenosis. A severely narrowed aortic valve must be replaced surgically, with either an artificial or a biological valve. An artificial valve has two metallic “wings” that open and close it. They have the advantage of lasting for an unlimited time, but medication has to be taken to thin the blood for the rest of the patient’s lifetime, to prevent the formation of blood clots. Biological valves are made from the pericardium (heart sac) of cows or pigs. With these biological prostheses lifelong blood thinning is not necessary but they must be replaced after 10-15 years. The heart surgeon selects the type of valve to be implanted in detailed discussion with the patient.
Conventional Aortic Valve Surgery
The conventional operation is performed on the open heart, with the breastbone divided and the ribs splayed. The heart-lung machine takes over the function of both these organs. The heart is stopped, the aorta is opened and the diseased heart valve is removed, together with calcium deposits. The surgeon sews the new heart valve into place and then closes the aorta again. Next the patient’s circulation is restarted. Finally an ultrasound probe is introduced into the esophagus to check the function of the new valve.
Minimally Invasive Aortic Valve Surgery
With the minimally invasive operation method the breastbone is not completely divided or not divided at all. Access to the heart is gained through an incision on the right side of the chest. We check carefully in each patient whether a minimally invasive procedure is possible. If the risk of even a minimally invasive operation is very high, for example due to advanced age of the patient, a new kind of valve can be implanted via a heart catheter.