The aortic valve is the protective valve that lies between the left ventricle and the aorta. It regulates the flow of blood from the left ventricle to the rest of the body.
The normal anatomy of the aortic valve has been described here. Briefly, it consists of 3 leaflets that close together like a Mercedes Benz sign.
The anatomy of the aortic valve can vary. In some patients, it can only have 2 leaflets instead of 3. This condition is described as a bicuspid aortic valve. Let’s take a look at this further.
What is a bicuspid aortic valve?
A bicuspid aortic valve is an aortic valve that has just 2 leaflets, not 3. It was first recognised by Sir William Osler, a doctor in Canada in the late 1800’s.
We have already spoken elsewhere about how the normal aortic valve has 3 leaflets. These 3 leaflets open to allow blood to flow through it, and then stop to prevent further flow. When the valve shuts close, the leaflets join each other at the ‘line of coaptation’. In the normal valve there are 3 lines of coaptation.
In a bicuspid valve, one of the lines of coaptation is fused. It therefore appears that the valve has 2 leaflets.
How common is it?
It is believed that bicuspid aortic valves are present in 1-2% of the general population worldwide. There are no specific statistics on Indians. Men tend to be affected twice as much as women. It is a birth defect that can remain silent and undetected for a number of years. Sometimes, a bicuspid aortic valve may be detected on autopsy.
It is possible that bicuspid aortic valve is a genetically transmitted condition, though not every generation is affected.
Clinical signs and symptoms
A large proportion of patients with bicuspid aortic valve do not have any symptoms. However, 1 in 3 patients may develop some type of complication (discussed later).
On examination of the patient by the doctor, there may not be any findings at all. In other words, a bicuspid aortic valve can be completely silent and hidden for a long time.
That being said, there are some patients who develop complications. One such complication is the development of narrowing of the valve (aortic stenosis). This can occur later in life, though in some cases it may be rather critically narrowed in infancy itself. Narrowing later in life takes place due to thickening of the valve leaflets and deposition of calcium on the surface. The valve can become weak as well, leading to leaking of blood back into the heart (aortic regurgitation). This leaking can be seen in up to 20% of patients.
Occasionally, narrowing and leaking may be present at the same time. The other complications are discussed later in this article.
The clinical symptoms that a patient develops is due to the narrowing or leakage of the valve. Dizziness, chest pain when walking and difficulty breathing are some of the common symptoms.
Diagnosis
The diagnosis of a bicuspid aortic valve is best made through echocardiography. The image and video below demonstrate what the valve looks like on a scan.
What happens if I have bicuspid aortic valve disease?
If you (or your child) have had a diagnosis of bicuspid aortic valve made, you may be wondering what would happen in the future. The following points may help you.
1. Most patients with bicuspid aortic valve do not have any symptoms for a long time.
2. It is estimated that only 1 in 50 children with this condition will develop valve disease (narrowing or leaking) by adolescence.
3. The development of complications depends on the presence of other risk factors. Patients with no associated risk factors rarely developed any problems. The risk increased to over 60% if they had more than 1 risk factor for heart disease.
4. Patients with bicuspid aortic valve disease without any other heart problems have the same life expectancy as the general population.
What are the complications?
There are certain complications associated with having this condition.
1. Narrowing of the aortic valve – This is called aortic stenosis.
2. Leakage of the aortic valve – This is called aortic regurgitation
3. Weakening of the heart muscle – This is called heart failure.
4. Infection of the heart valve – This is called endocarditis
5. Aortic aneurysm – This refers to enlargement of the aorta just beyond the point where the aortic valve is present.
Patients who have a bicuspid aortic valve often have other heart and blood vessel conditions associated with it. These include coarctation of the aorta, Williams syndrome and patent ductus arteriosus (PDA). It is also seen in patients with Turner’s syndrome.
How is it treated?
Firstly, if you are diagnosed with a bicuspid aortic valve, don’t panic. Majority of patients do not have symptoms.
In those who do have symptoms, they often arise due to narrowing or leakage of the valve.
Medical treatment
There is no specific medical treatment for this condition. However, patients will require constant review in clinic – usually once a year. Every year an echocardiogram may be performed to determine the state of the valve.
Patients who have heart failure may need ACE inhibitors, beta blockers and diuretics.
Surgical treatment
Surgery is only offered if there is narrowing or leakage of the valve and the patient has symptoms.
Previously, patients who had bicuspid valves required a short course of antibiotics before they underwent any dental procedure. However, new guidelines have stated that this is no longer necessary. In India, the new guidelines are not in effect, and hence all patients who are undergoing any dental procedures will be given antibiotics by their doctor.