Bicuspid aortic valve

A bicuspid aortic valve (BAV) is a defect of the aortic valve that results in the formation of two leaflets or cusps instead of the normal three. Normally only the mitral valve (bicuspid valve) has two cusps (instead of three); situated between the left atrium and left ventricle. Valves ensure the unidirectional flow of blood from the atrium to the ventricles, or the ventricles to the major arteries and veins.

Incidence/prevalence
About 1–2% of the population have bicuspid aortic valves (BAV), although the condition is nearly twice as common in males. This disease can lead to other heart complications such as an enlarged aorta.

It is more common than any other congenital cardiac anomaly.

Bicuspid aortic valve is an inheritable condition, with a demonstrated association with Notch 1. Both familial clustering and isolated valve defects have been documented. The incidence of bicuspid aortic valve can be as high as 10% in families affected with the valve problem. Other congenital heart defects are associated with bicuspid aortic valve at various frequencies, including coarctation of the aorta.

Presentation
In many cases, a bicuspid aortic valve will cause no problems. However BAV may become calcified later in life, which may lead to varying degrees of severity of aortic stenosis that will manifest as murmurs. If the leaflets do not close correctly, aortic regurgitation can occur. If these become severe enough, they may require heart surgery. People with BAV may become tired more easily than those with normal valvular function and have difficulty maintaining stamina for cardio-intensive activities-due to poor heart performance. The heart is put under more stress in order to either pump more blood through a stenotic valve or attempt to circulate regurgitation blood through a leaking valve.

Diagnosis, treatment, and prognosis
The condition can be associated with a heart murmur located at the right second intercostal space. Often there will be differences in blood pressures between upper and lower extremities. The diagnosis can be assisted with echocardiography (EchoCG) or magnetic resonance imaging (MRI).

Most patients with bicuspid aortic valve whose valve becomes dysfunctional will need careful follow-up and potentially valve replacement at some point in life. Regular EchoCG and MRI may be performed. For diagnosed patients, genetic testing is done to allow for future offspring with the disease to be monitored and treated early in life.

Patients with bicuspid aortic valve should be followed by cardiologist or cardiac surgeon with specific interest in this valve pathology.

Average lifespan is similar to that of those without the anomaly.

Aorta complications
An important associated problem is that the aorta of patients with bicuspid aortic valve is not normal in strength or size.

Aortas of patients with a bicuspid aortic valve do not have the same histological (cellular) characteristics of a normal aorta. In particular, the tensile strength of the aortal wall is reduced, which causes these patients a higher risk for aortic dissection and aneurysm formation of the ascending aorta. The size of the proximal aorta should be evaluated carefully during the work-up. The initial diameter of the aorta should be noted and annual evaluation with CT scan, or MRI to avoid ionizing radiation, should be recommended to the patient; the examination should be conducted more frequently if a change in aortic diameter is seen. From this monitoring, the type of surgery that should be offered to the patient can be determined based on the change in size of the aorta.

Patients with bicuspid aortic valve are also at higher risk of aortic coarctation, an abnormal narrowing of the thoracic aorta.