Aortic Valve is located between the left ventricle and the aorta in the heart. Ordinarily it is a tricuspid valve (meaning it has three leaflets), although in 2% of the population it is found to be bicuspid (two leaflets). When functioning properly pressure rises in the left ventricle, the aortic valve opens, and blood exits the aortic valve and flows into the aorta. During the flow of blood through the aortic valve pressure decreases in the left ventricle and forces the aortic valve shut. The change in pressure due to the closing of the aortic valve constitutes the second heart sound.
Aortic Valve Disorder
Before the sophisticated medicine and treatment we have today, aortic valve disease was the most common valvular problem. There are typically three ways that an aortic valve disorder can develop.
Those who are born with a bicuspid aortic valve are at a possible risk later on in life. This is because the bicuspid valve doesn’t open as widely as its tricuspid counterpart. This causes more pressure on the aortic valve leaflets, and leads to increased wear and tear over time, resulting in aortic valve stenosis. About 10% of bicuspid aortic valves become significantly narrowed, resulting in this aortic valve disorder.
The most common cause of aortic valve stenosis is due to protein collagen on the aortic valve being destroyed (commonly with elderly people). Calcium begins to deposit on the aortic valve leaflets, and the mobility of the aortic valve is decreased. This can cause aortic valve leakage, which can lead to other complications.
Less common in first world countries, aortic valve disease can also be caused by an infection that develops with rheumatic fever (an illness that follows strep throat if it is left untreated). The infection causes the edges of the aortic valve to fuse (bind together) and become weakened, thus resulting in a leaky aortic valve.
Symptoms of Aortic Stenosis
Major symptoms of aortic stenosis are chest pain (angina), fainting (syncope), and shortness of breath (due to aortic valve leakage and heart failure). In 4% of patients with aortic stenosis, the first symptom is sudden death, usually resulting from strenuous physical activity.
In about one third of all patients diagnosed with aortic valve stenosis, chest pain is usually the first sign. The pain is described as uncomfortable pressure below the rib cage, becoming worse during physical exertion and usually relieved during rest. Because the aortic valve is narrowed, this increases pressure in the heart. It also increases the oxygen demand for the blood flowing into the heart because there is less blood being pumped by the heart due to the narrowing of the aortic valve. This can also attribute to shortness of breath.
Fainting (syncope) is another symptom of aortic valve disease and is usually associated with physical exertion or excitement. This is because the narrowed aortic valve cannot supply the right amount of pressure to blood veins in the body, resulting in a drop of blood pressure. Since blood flow to the brain is decreased as a result of this, fainting can occur.
Shortness of breath is caused by an increased pressure load on blood vessels of the lung. This is due to the fact there is increased pressure on the aortic valve, and therefore pressure is increased on all blood flow leading to the aortic valve. Initially, patients suffering from aortic valve stenosis will feel a shortness of breath during physical activity, although as the aortic valve disease progresses, shortness of breath can also occur during rest.
Aortic Valve Surgery
Patients with mild aortic stenosis do not require to be treated to refrain from any activity. Once the aortic valve stenosis becomes categorized as “moderate”, patients are typically advised to avoid strenuous activities such as sprinting or weight lifting. Doctors and their patients are most often aware of aortic valve stenosis as it progresses. That being said, patients are then monitored annually by use of echocardiography (ultrasonography of the heart). Patients with a serious progression of aortic valve stenosis are likely to be given antibiotics prior to any sort of procedure in which bacteria may enter the blood stream. This includes but is not limited to dental work and minor surgery.
Patients categorized with severe aortic valve stenosis are usually recommended to go in for aortic valve surgery. There are two main types of procedures in which aortic valve surgery is performed: aortic valve repairand aortic valve replacement.
Aortic Valve Repair
Aortic valve repair can usually be performed on valve defects that are congenital. Although valve repair is more commonly used to treat mitral valve defects, it’s still a viable procedure. The following are six procedures that surgeon use depending on how the aortic valveappears to be defective:
Commisurotomy, which is used when the aortic valve becomes too narrow. The leaflets of the aortic valve are too wide and can obstruct the flow of blood. The surgeon cuts the points where the leaflets are too wide.
Valvuloplasty, an action taken when the leaflets of the aortic valveare weakened. A ring-like device is attached to the outside of the aortic valve for support.
Reshaping, which involves the cutting and re-stitching of misshapen aortic valves.
Decalcification, which involves the removal of calcium which can build up on the aortic valve leaflets, allowing them to close properly and preventing aortic valve leakage.
Repair of structural support, where cords that support the aortic valve are shaped to the right length, allowing the aortic valve to close properly.
Patching, where holes in the aortic valve leaflets are patched, thus preventing aortic valve leakage.
Aortic Valve Replacement
Aortic valve replacement is a much more common procedure than aortic valve repair, because patients usually don’t develop life threatening complications that can be solved by aortic valve repair. There are two different types of aortic valve replacements: biological and mechanical. Both biological and mechanical aortic valve replacements have their advantages and disadvantages, and communication between a doctor and his/her patient should determine which aortic valve replacement is best.
Mechanical aortic valve replacement materials usually consist of things such as plastic, carbon or metal. These last much longer than their biologicalcounterpart. The downside of a mechanical aortic valve replacement is that patients will have to take blood-thinning anticoagulants for the rest of their lives to prevent blood clotting to the mechanicalparts of the valve.
Biological aortic valve replacements are either made from animal tissue, or the human tissue of a donated heart. Because the aortic valve replacementis made from biological materials as opposed to mechanical ones, patients usually do not require to take anticoagulants to prevent blood clotting. However, biological valves need to be replaced after 10 years or so. In children and young adults, the biological aortic valve replacement naturally breaks down quicker, so these replacements are most often used in elderly patients.