Bicuspid Aortic Valve - An Abnormality in Heart Anatomy

Introduction:

A bicuspid aortic valve is a congenital condition in which an aortic valve is present with two leaflets (cusps) instead of three. An aortic valve is normally tricuspid. The heart has four valves, namely, the aortic valve, mitral valve, tricuspid valve, and pulmonary valve. The aortic valve is positioned between the left ventricle, the lower chamber on the left side of the heart, and the primary artery known as the aorta. The aortic valve lets oxygenated blood flow from the heart to the aorta. When the heart contracts, the aortic valve opens and allows the blood flow from the left ventricle to enter the aorta. During the relaxation phase of the heart, the aortic valves seal shut to prevent the reverse flow of blood. However, if the aortic valve is damaged or diseased, it can impede the blood flow, causing the heart to face difficulties in pumping blood to other organs in the body. The bicuspid valve can leak (aortic regurgitation) and narrow (aortic stenosis). The bicuspid aortic valve is a common congenital condition as approximately two percent of the population has this condition. Men are twice more likely to have bicuspid aortic valves than women.

What Is the Cause of the Bicuspid Aortic Valve?

The exact cause of the bicuspid aortic valve is still unknown. The bicuspid aortic valve is a congenital condition, and it often runs in the family. It is also seen that it develops early in pregnancy. This condition seems to be an inherited heart defect, but the researchers have not understood it correctly.

What Are the Signs and Symptoms of a Bicuspid Aortic Valve?

A bicuspid aortic valve is often asymptomatic. With age, conditions like stenosis (narrowing of the valve) or regurgitation (blood leaks backward because the aortic valve does not close tightly) develop, and the person starts to feel the signs and symptoms associated with these conditions.

Signs and symptoms seen in adults:

• Pain and discomfort in the chest region.

• Tiredness (fatigue).

• Sudden shortness of breath.

• Loss of consciousness or lightheadedness.

• Abnormal heart sound (heart murmur).

Signs and symptoms seen in infants and children:

• Difficulty in breathing.

• Fainting.

• The skin turns pale.

• Difficulty in feeding or weight gain.

• Getting tired easily.

• Pain in the chest region.

What Are the Complications of the Bicuspid Aortic Valve?

The possible outcomes of the bicuspid aortic valve are:

• Aortic Stenosis - This condition can be explained as the narrowing of the aorta(the main artery branching off the heart).

• Aortic Regurgitation - This happens when the aortic valve does not close properly and lets the backward flow of the blood and blood enter the left ventricle.

• Infective Endocarditis - It is an infection of the lining of the heart valve and heart chambers because of bacteria that enter the bloodstream and settle in the heart lining.

• Thoracic Aortic Aneurysm - This condition develops due to the weakened area in the wall of the aorta in the chest region. With time, the blood vessel balloons and has a risk of bursting or separating.

• Aortic Dissection - This condition represents a medical emergency characterized by a tear in the inner layer of the aorta.

How to Diagnose a Bicuspid Aortic Valve?

Although the bicuspid aortic valve is present since birth, it remains asymptomatic and undiagnosed until the person shows signs and symptoms, usually in adulthood. The doctor, using the stethoscope, examines the patient for abnormal heart sounds or heart murmur, which is the first sign of the bicuspid aortic valve. After that, the doctor would recommend the following tests:

• Transthoracic Echocardiogram - This test allows the doctor to have a proper view of the heart and check heart sounds and heart conditions. It is done by moving an instrument called a transducer that resembles a microphone over the chest region. This transducer sends sound waves into the chest and receives echoes from the different parts of the heart.

• Transesophageal Echocardiogram - This test is done to assess the structure and function of the heart. In this test, a probe with a transducer is inserted down the esophagus that provides a clear image of the heart as the sound waves do not have to cross the skin, muscle, or bone tissue to reach the heart.

• CT (Computed Tomography) Scan - This test uses multiple X-rays from different angles to construct a detailed image of the heart.

• Cardiac MRI (Magnetic Resonance Imaging) Scan - The MRI scan shows the parts of the heart and their functioning too. It uses radio waves and magnetic fields to produce clear and detailed pictures of the structure of the heart.

• Coronary Angiography - This test is done to check for any restriction in blood flow going to the heart. It uses X-ray imaging to visualize the blood vessels of the heart.

What Are the Treatment Options for the Bicuspid Aortic Valve?

The treatment options include:

Surgery - It is important to go to surgery to avoid further complications and heart damage. About 80 % of the patients require repair or replacement of the aortic valve. The surgery type is decided based on the specific condition and symptoms of the patient.

• Aortic Valve Replacement - During this surgical procedure, the surgeon eliminates the impaired valve and substitutes it with either a mechanical valve or a biological tissue valve, which can be derived from pig, cow, or human heart tissue, or occasionally from the patient's own pulmonary valve. Patients with mechanical valves are given blood thinners all their life to prevent blood clots. Individuals who possess a biological tissue valve will receive information regarding its gradual deterioration over time and the potential necessity for eventual replacement. The doctor will engage in a discussion concerning the advantages, drawbacks, and suitability of various valve options for the patient.

• Aortic Root and Ascending Aorta Surgery - In this procedure, the surgeon removes the enlarged part of the aorta located near the heart and replaces it with a synthetic tube (graft). The aortic valve is also removed and replaced during the procedure.

• Balloon Valvuloplasty - This procedure is recommended in cases where aortic stenosis is caused by the aortic valve. The surgeon enters a catheter with a balloon on the tip into the groin’s artery and guides it to the aortic valve. On inflating the balloon, the opening of the valve expands. Then the air is let out, and the balloon deflates. The catheter and the balloon are removed from the patient’s artery. In these patients, there is a tendency for the aortic valve to narrow once again.

Medication - Medicines are prescribed so that the patient can have some relief from symptoms and prevent complications. No medication is currently accessible for treating the bicuspid aortic valve.

• Beta-blockers and ACE (Angiotensin Converting Enzymes) Inhibitors - These medicines lower the workload on the heart.

• Inotropic Agents - These drugs help the heart in pumping harder.

• Diuretics - These medicines help in getting rid of body salts and water.

Conclusion:

The bicuspid aortic valve is a birth defect, but it usually remains undiagnosed till the symptoms are visible. Once it is diagnosed, the patient has to have regular checkups with the doctor for life. Individuals with this condition are prone to developing infections, and maintaining good oral hygiene can aid in reducing the risk of infection. As it is considered an inherited condition, the family members of the patient are often recommended to get screened for the same condition.