What is a bicuspid aortic valve?;

The human heart has four valves (aortic, mitral, pulmonary, tricuspid). The main function of these valves is to direct the flow of blood from one part of the heart to another. The aortic valve is the last valve that blood will pass through before exiting the heart and out into the aorta, the large vessel that will carry blood throughout the body. The aortic valve usually has three “leaflets” (also known as cusps) that open to let blood through and then close to let blood out of the body and not back up to the heart.

Bicuspid aortic valve will be seen in 1-2% of the population. In the bicuspid aortic valve usually two of the “leaves” are fused at birth and therefore the valve appears to have only two “leaves”. This condition can be random or it can be hereditary in some families. It is also associated with some syndromes (e.g. Turner syndrome) and in a percentage of patients another heart condition will be found at the same time such as interventricular defect, patent ductus arteriosus (or ductus arteriosus), or aortic isthmus stenosis. The presence of the bicuspid aortic valve carries an increased risk for two categories of disease: the aortic valve and the aorta (the large vessel that carries all the blood when it leaves the heart).

Aortic valve diseases

Bicuspid aortic valve has an increased risk for stenosis or regurgitation. In stenosis, it is difficult for the blood to leave the heart, resulting in hypertrophy of the heart muscle. In aortic valve insufficiency, the valve does not “close” completely, resulting in the blood that has just exited returning to the heart. A consequence of this insufficiency of the aortic valve is that the heart enlarges from the overload of blood volume.

Diseases of the aorta

People with a bicuspid aortic valve have an increased risk of developing an aneurysm of the aorta, the large vessel that carries all the blood from the heart to the body. There are two theories as to why aneurysms form in patients with a bicuspid aortic valve. One theory suggests that it is due to abnormal blood flow pushing against the walls of the aorta. The other theory suggests that it is due to congenital changes in the composition of the walls of the aorta.

Aortic aneurysms can be located in the aortic root (the initial part of the aorta just after the aortic valve), the ascending aorta (the middle part), or the aortic arch (the part of the aorta where the arteries for the upper extremities and the brain).

Aortic aneurysms also carry an increased risk of aortic dissection (tearing the walls) or aortic rupture (breaking the aorta completely). Aortic dissection and rupture are extremely dangerous and urgent conditions and therefore surgery is recommended in specific cases to avoid this risk.

Diagnosis

The diagnosis of bicuspid aortic valve will be established by triplex echocardiography. Also, computed tomography, and especially computed tomography with electrocardiographic resonance, can establish the existence of the bicuspid valve. Aortic aneurysm will be best measured by computed tomography (also known as CT angiography of the thoracic aorta) but also echocardiography and magnetic resonance imaging are good alternative methods for imaging the aneurysm.

When valve dysfunction or aneurysm size require monitoring imaging will usually be recommended every 6 to 12 months as appropriate.

Indication and choice of surgery for the aortic valve

Aortic valve surgery will be recommended when the valve becomes severely narrowed or severely incompetent. Usually the patient will have symptoms of shortness of breath on exertion. Also, there may be an indication for valve surgery with moderate valve dysfunction if the patient will be operated on for another reason (either for aortic aneurysm or coronary disease usually).

In valve stenosis, the valve must be replaced with either a biological valve (made from processed animal tissue) or a mechanical valve. The biological aortic valve does not require the patient to take anticoagulants but has a lifespan of 10-20 years. After this period of time it will malfunction and require reoperation. The mechanical aortic valve requires the patient to receive anticoagulation but can function for the patient’s lifetime. In younger patients there is usually a preference for a mechanical valve and in older patients a biological valve is preferred.

In aortic valve insufficiency there is the option, in certain cases, to repair the valve. Tissue quality, the presence of calcium, the condition of the aortic annulus, and other factors will be taken into account to assess the likelihood of repair. There are multiple valve repair techniques from suturing the glottis tissue, supporting the glottis with various sutures, and techniques to support the aortic annulus with either a ring or a special suture that will shrink the aortic annulus. In cases where the valve cannot be repaired, the valve will be replaced.

Valve surgery can be performed in multiple ways (sternotomy, mini-incision, thoracoscopic, robotic, and fully percutaneous with a catheter). The patient’s anatomy and other medical conditions will be evaluated to select the most appropriate approach for each patient.

Indication and choice of surgery for aortic aneurysm

Aortic aneurysms are operated when they are more than 50 mm in experienced cardiac surgery centers, more than 45 mm when aortic valve surgery will be performed at the same time and also when the diameter increases more than 5 mm in one year or more than 3 mm per year for two consecutive years. There are many options for aneurysm repair with techniques such as: David, Bentall, Yacoub, Bio-Bentall, use of homografts and many others. When simultaneous aortic valve and aneurysm surgery is needed, the possibility of valve repair, the type of valve that will be preferred if replacement (biological or mechanical) and the age and other diseases of the patient will be taken into account. These operations can be performed minimally invasively and in some cases completely percutaneously with a catheter. Recent improvements in surgical techniques and developments in valve and graft materials promise excellent results for the patient who will need them.

Conclusions

Bicuspid aortic valve is the most common congenital heart disease. Patients with a bicuspid aortic valve have an increased risk for aortic valve dysfunction as well as aortic aneurysm development. Regular monitoring with echocardiography for the valve and CT scan for the aneurysm will protect the patient and document the presence of an indication for surgery. Bicuspid aortic valve and co-existing aneurysm procedures can now be performed minimally invasively or percutaneously in most cases. Advances in surgical techniques and materials promise excellent results for patients.

Our heart is the source of our life. September is dedicated to World Heart Day, let’s remember how important it is to take care of our heart every day. A healthy heart contributes to more moments of happiness and well-being with our loved ones.