Unicuspid Aortic Valve - Types, Diagnosis, and Treatment

Introduction:

The unicuspid aortic valve is a rare congenital abnormality that was initially described by Edwards in 1958. It is frequently misidentified as a bicuspid aortic valve. Patients with a unicuspid aortic valve are always relatively young when they are diagnosed or have surgery, ranging in age from 14 to 75 years, indicating an earlier beginning and a faster rate of development of aortic stenosis (aortic valve is constricted and does not fully open). The most common disease in patients with a unicuspid aortic valve is severe aortic stenosis or combined stenosis and regurgitation (backflow of the blood). The unicuspid aortic valve, like the bicuspid aortic valve, is prone to dilatation or dissection of the aorta, including the aortic root, ascending aorta, or aortic arch, and often necessitates surgical intervention. Aortic coarctation (birth defect with narrow aorta), a single coronary artery, an abnormal right subclavian artery, and ventricular septal defects are also related to diseases.

What Are the Types of Unicuspid Aortic Valves?

The adult population's annual incidence of unicuspid aortic valves is predicted to be 0.02 %. However, it occurs at a rate of four percent to five percent in patients undergoing surgery for isolated aortic stenosis. There are two forms of unicuspid aortic valves:

1. Acommissural Pin-Hole-Shaped - This form has no lateral attachment with a central orifice to the aorta.

2. Unicommissural Slit-Shaped - This type has one attachment with an eccentric aperture.

How Do Unicuspid Aortic Valves Develop?

A proper aortic valve with valve cusps, sinuses, and commissures develops during embryogenesis. A typical tri-leaflet aortic valve is made up of three cusps and three related commissures that grow from embryonic aortic trunk tubercules. The unicuspid aortic valve occurs when the three aortic cusps fail to separate before birth.

1. Unicuspid Acommissural Valve - At the level of the orifice, the unicuspid unicommissural valve has no commissures or lateral attachments to the aorta and appears as a pinhole on imaging. As a result, significant aortic stenosis occurs at a young age, and patients may present for surgical repair as early as birth or infancy.

2. Unicommissural Unicuspid Aortic Valve - It has one lateral commissural attachment to the aorta at the level of the orifice and appears as a slit-shaped feature in its morphology. Because the orifice in unicommissural unicuspid aortic valves is larger than that in acommissural unicuspid aortic valves, these patients generally stay asymptomatic until their third to fifth decade of life. Males are more likely than females in the ratio of 4:1 to have a unicuspid aortic valve.

What Are the Symptoms of a Unicuspid Aortic Valve?

The most common adult symptoms of the unicuspid aortic valve are:

1. Dyspnea (difficulty breathing).

2. Angina (heart attack).

3. Dizziness.

4. Syncope (fainting).

Left heart failure and failure to thrive are always present in pediatric patients. Pneumonia may appear within the first two months of life. The presence of a cardiac murmur at the aortic area is the most noticeable aberrant result on physical examination. The other cardiac problems associated are as follows:

1. Patent ductus arteriosus (continuous aperture between the two main blood arteries exiting the heart).

2. Coarctation of the aorta.

3. Aortic dilatation.

4. Aortic regurgitations (inadequate aortic valve closure resulting in reverse blood flow via the aortic valve).

5. Aortic aneurysm (aortic ballooning).

6. Aortic dissection (rip in the aorta's interiors).

How to Diagnose Unicuspid Aortic Valves?

In order to assess the aortic valve morphology, including the exact morphology of the aortic valve as well as the severity of aortic stenosis and regurgitation, the following tests can be done:

1. Magnetic resonance imaging.

2. Cardiac computed tomography.

3. Multislice tomography angiography.

4. Echocardiography.

In most individuals, echocardiographic imaging enables for accurate diagnosis of aortic valve morphology. Furthermore, it can discriminate between actual and false unicuspid aortic valves.

As the absence of cusp separation during aortic valve opening displays the eccentric teardrop opening in a unicommissural unicuspid aortic valve, echocardiography is best used to assess the unicuspid aortic valve.

How Is the Unicuspid Aortic Valve Treated?

Patients withunicuspid aortic valve develop symptoms of aortic stenosis 20 to 30 years sooner than those with a normal trileaflet aortic valve. The unicuspid aortic valve has a bimodal presentation, with older patients having a less aggressive type and younger patients having a more aggressive version. The techniques for unicuspid aortic valve treatment vary greatly between adults and children. In children, the most common procedures are:

1. Aortic Balloon Valvuloplasty: A surgery that extends the aortic valve to alleviate the symptoms of aortic stenosis.

2. Surgical Valvotomy: A minimally invasive treatment that involves the opening of a constricted heart valve.

3. Commissurotomy: Surgery to enhance blood flow across the heart valves.

4. The Ross Operation: Heart valve replacement surgery.

Some are palliative operations that may be linked to persistent or recurring valve malfunction and reintervention because severe acommissural form frequently requires these therapies from infancy.

• Aortic Valve Replacement - Aortic valve replacement (AVR) is the most often used therapeutic method in adults. Many people require AVR in their forties, on average, in their third decade of life. This procedure can be done when the maximal aorta diameter exceeds 5 cm. Isolated aortic stenosis is the most prevalent of the various valve diseases linked with unicuspid aortic valves. Symptoms of aortic stenosis usually appear when the:

1. Transvalvular mean gradient exceeds 40 mmHg.

2. Aortic jet velocity exceeds four meter per second.

3. The valve area is less than one centimeter square.

Conclusion:

The unicuspid aortic valve is an uncommon congenital cardiac defect of the aortic valve that usually manifests in the third to fifth decade of life. It might cause significant valve malfunction, as well as accompanying clinical appearance and other problems. Echocardiography is the foundation of the imaging technology used to detect unicuspid aortic valves. Multi-modality imaging has played a major part in diagnosis and may increase diagnostic accuracy. The unicuspid aortic valve is frequently misdiagnosed as a bicuspid aortic valve, yet there are important differences between the two. It is critical to accurately identify aortic valve morphology in order to select the optimal treatment. Adults and children have various treatment techniques. Many unicuspid aortic valve sufferers may require surgical intervention at a young age.