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Bicuspid aortic valve: Basics and beyond

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Release date: October 1, 2018
Expiration date: September 30, 2019
Estimated time of completion: 1 hour

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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.


 

References

Bicuspid aortic valve may initially be asymptomatic, but it is associated with progressive valvular and aortic abnormalities that can lead to chronic heart failure and sudden death. Regular monitoring is required with an eye toward surgery when indicated.

See related editorial

This article reviews inheritance patterns and conditions associated with bicuspid aortic valve. We discuss diagnosis, management, and monitoring, and offer surgical recommendations. Special guidance for dental procedures, pregnancy, and athletes is also provided.

A YOUNG MAN WITH PALPITATIONS AND A MURMUR

A 34-year-old man presented to an outpatient clinic with occasional palpitations over the past several months. He reported that he had been diagnosed with a murmur as a child but had received no further testing.

Physical examination at this time revealed a faint systolic crescendo-decrescendo murmur along the right sternal border without radiation to the carotid arteries or to the apex. Transthoracic echocardiography (TTE) showed a bicuspid aortic valve with fusion of the right and left coronary cusps, with no aortic valve stenosis or insufficiency. There was mild dilation of the aortic root, but the mid-ascending aorta could not be evaluated because of limited acoustic windows.

Is further diagnostic testing needed, and if so, what? May he participate in exertional physical activity? Does his newborn son need evaluation?

ABNORMALITIES OCCUR DURING EMBRYOGENESIS

Bicuspid aortic valve develops because of abnormal valvulogenesis. Adjacent cusps fail to separate from each other, resulting in only 2 cusps, with 1 usually larger than the other. Morphology varies according to which commissures are fused.1

Bicuspid aortic valve is associated with abnormalities in the coronary artery anatomy in about 2% of patients, including anomalous origins of the coronary arteries and upwardly displaced coronary ostia.2 Such features need to be considered before surgical intervention.

Bicuspid aortic valve can be found in 1% to 2% of the general population, with a male-to-female predominance of 3:1.1,3,4 It is one of the most common congenital cardiac malformations and is the leading congenital cause of aortic valve stenosis.1,3 However, routine screening of newborns for the condition is not recommended, and most cases are diagnosed incidentally.

GENETIC FACTORS PROMINENT

Bicuspid aortic valve is thought to be primarily inherited in an autosomal-dominant pattern, but there is evidence of genetic heterogeneity, and the pattern may be variable.5,6

No single gene responsible for bicuspid aortic valve has been identified. The condition may occur as a component of different pleiotropic genetic syndromes such as Loeys-Dietz, DiGeorge, and Marfan syndromes,7,8 as well as in patients with Turner syndrome and Williams syndrome.8–11 It also commonly coexists with other congenital heart diseases, including ventricular septal defect, isolated aortic arch obstruction, and patent ductus arteriosus.9

Studies have found a 15% rate of familial clustering.6,12 In a study of 142 patients with bicuspid aortic valve, 20% of first-degree relatives had some cardiac abnormality found by screening, of whom 68% had bicuspid aortic valve. Of these, 71% were newly detected abnormalities.13

CHARACTERISTIC CLICK AND MURMUR

Physical examination findings of a functionally normal bicuspid aortic valve include a systolic ejection click followed by an early peaking systolic murmur at the apex or left lower sternal border. With progression of aortic stenosis, the ejection murmur has a harsher sound, with later peaking, and the S2 sound diminishes or becomes inaudible.14 If aortic regurgitation is present, a diastolic decrescendo murmur is heard best at the left lower sternal border.

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