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Bicuspid aortic valve: Basics and beyond

Cleveland Clinic Journal of Medicine. 2018 October;85(10):779-784 | 10.3949/ccjm.85a.17069
October 1, 2018|Cleveland Clinic Journal of Medicine
Shailee Y. Shah, MD;Andrew Higgins, MD;Milind Y. Desai, MD, FACC, FAHA, FESC
Author and Disclosure Information

Shailee Y. Shah, MD
Department of Internal Medicine, Cleveland Clinic

Andrew Higgins, MD
Heart and Vascular Institute, Cleveland Clinic

Milind Y. Desai, MD
Haslam Family Endowed Chair in Cardiovascular Medicine, Department of Cardiovascular Medicine, Heart and Vascular Institute, and Department of Diagnostic Radiology, Cleveland Clinic; Professor, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH

Address: Shailee Y. Shah, MD, Department of Internal Medicine, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; shahs10@ccf.org

ABSTRACT

Bicuspid aortic valve, one of the most common congenital cardiac malformations, is associated with other valvular abnormalities and aortopathies. It increases the risk of thoracic aortic aneurysm and dissection, infective endocarditis, and sudden cardiac death. Patients require regular surveillance for progressive valvular disease and aortopathy. Although bicuspid aortic valve may occur sporadically, many cases are inherited, so first-degree relatives should be evaluated and genetic counseling considered.

KEY POINTS

  • Associated aortopathies such as aortic root dilation, aneurysm, dissection, and coarctation may initially be asymptomatic.
  • Regular surveillance with transthoracic echocardiography (TTE) is required.
  • Transesophageal echocardiography should be performed if TTE does not clearly show the aorta and aortic root. Magnetic resonance imaging or computed tomographic angiography may also be needed to measure the aortic root and ascending thoracic aorta.
  • If initial imaging is normal and there is no aortic dilation, repeat imaging should be done every 5 to 10 years. If any abnormality is found, annual surveillance is needed.
  • Women with a bicuspid aortic valve who are contemplating pregnancy should undergo echocardiography first, and some may need to undergo surgery.

EXERCISE RESTRICTIONS

The 2015 ACC/AHA guidelines for competitive athletes with cardiovascular abnormalities recommend annual screening with TTE or MRI angiography for athletes with bicuspid aortic valve and coexisting dilation of the ascending aorta (aortic diameter 40–42 mm in men and 36–39 mm in women) (class I recommendation, level of evidence C).29

Athletes with a bicuspid aortic valve and a normal aortic root and ascending aorta may participate in all competitive activities.29 However, those with a dilated aorta should avoid strenuous activities because of the increased risk of rupture.30 The ACC/AHA recommendations29 depend on the diameter of the ascending aorta and the nature of the sport:

  • For an aortic diameter 40 to 42 mm in men or 36 to 39 mm in women, and no features of connective tissue disease or familial thoracic ascending aortic syndrome, low- and moderate-intensity sports with a low likelihood of significant body contact may be considered; consider avoiding intense weight training (class IIb, level of evidence C)
  • For an aortic diameter 43 to 45 mm, low-intensity sports with a low likelihood of body contact may be considered (class IIb, level of evidence C)
  • For an aortic diameter greater than 43 mm in men or greater than 40 mm in women, sports involving body collision should be avoided (class III, level of evidence C)
  • For an aortic diameter greater than 45 mm, sports activities should be avoided (class III, level of evidence C).

PREGNANCY CONSIDERATIONS

Bicuspid aortic valve is associated with aortic dissection, mainly in the third trimester.31 Patients should ideally undergo echocardiographic screening before conception. The 2010 ACC/AHA guidelines for managing thoracic aortic disease recommend monthly or bimonthly echocardiography until delivery in pregnant women with a dilated thoracic aorta.22

Patients with bicuspid aortic valve and aortic root enlargement of more than 40 mm should have preconception counseling about surgery for aortic root replacement before becoming pregnant. If the diagnosis of enlarged aortic root is made during pregnancy, echocardiographic surveillance at 4- to 6-week intervals is indicated.32

SURGICAL MANAGEMENT

In the past, beta-blockers and angiotensin-converting enzyme inhibitors were recommended to minimize shear stress, with the goal of slowing progression of aortic dilation. However, evidence to support their use is inadequate.33,34

The only definitive treatment is surgery, with various procedures that lower the risk of death or dissection.24,35

The dimensions of the aortic root or ascending aorta should be examined vigilantly, according to the 2014 ACC/AHA guidelines27:

  • Repairing the aortic sinuses or replacing the ascending aorta is indicated if the diameter of the aortic sinuses or ascending aorta is greater than 5.5 cm (class I, level of evidence B)
  • Repairing the aortic sinuses or replacing the ascending aorta is reasonable if the diameter of the aortic sinuses or ascending aorta is greater than 5.0 cm and the patient has a risk factor for dissection such as a family history of aortic dissection or an increase in diameter of 0.5 cm or greater per year (class IIa, level of evidence C)
  • Replacement of the ascending aorta is reasonable if the diameter of the ascending aorta is greater than 4.5 cm and the patient is undergoing aortic valve surgery for severe aortic stenosis or regurgitation.

Valve repair or replacement

Aortic valve repair or replacement is sometimes done separately from aortic root repair.

The value of aortic valve repair is debatable, but a series of 728 patients at Cleveland Clinic showed a very low mortality rate (0.41%) and an annual reoperation rate of 2.6% during up to 15 years of follow-up.36

Aortic valve replacement is usually considered for patients with severe valve dysfunction, abnormal left ventricular dimensions, or symptoms. It is important to determine if the patient is a good surgical candidate and to refer early for surgical evaluation to avoid the higher risk of death associated with emergency surgery.36

Transcatheter aortic valve replacement has been studied in patients deemed to be at too high a risk for surgical replacement. Short- and intermediate-term outcomes have been good in these patients, but long-term data are lacking.37

Surveillance after surgery

The type of operation determines postoperative surveillance.

After isolated aortic valve repair or replacement, patients should continue with surveillance at least annually to monitor for progressive aortopathy, as they remain at increased risk of dissection or rupture after isolated valve surgery, especially if they had aortic insufficiency preoperatively.38

After definitive surgery with replacement or repair of the ascending aorta, no clear recommendations have been established for continued surveillance. However, it is reasonable to image these patients with either MRI or CT angiography 3 to 5 years after their surgery to monitor for anastomotic complications.

CASE QUESTIONS ANSWERED

Our patient should undergo repeat TTE in 1 year. He should also undergo CT angiography of the ascending aorta if it is not seen by TTE. He can participate in low-intensity sports but should avoid intense weight training. His parents, siblings, and children should be screened for bicuspid aortic valve or associated aortopathies.

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