Aortic valve stenosis
Aortic valve stenosis (also known as aortic stenosis) is the most common type of valvular heart disease that requires valve replacement. It can be classified according to the anatomical location: supravalvular, valvular and subvalvular 1.
There are several causes of aortic valve disease that include a bicuspid aortic valve, degenerative aortic valve disease and rheumatic heart disease.
Bicuspid aortic valve is the most common congenital cardiac anomaly with a prevalence of 4.6 in 1,000 live births 5.
The incidence of degenerative aortic valve disease is increasing. Risk factors are closely associated with atherosclerosis including diabetes, smoking, hypertension and dyslipidaemia.
Rheumatic heart disease is the late sequelae of rheumatic fever, a rare multisystem disease caused by an immunological response to Group A streptococcus infection. The incidence is declining in developed countries and is more common in the Aboriginal and Maori populations and other disadvantaged groups worldwide.
- angina pectoris
- crescendo-decrescendo mid-systolic murmur
- increased risk of sudden cardiac death
- congenital: isolated or in association with William syndrome
- acquired: post-surgical or sequelae of aortitis
congenital (congenital aortic valve stenosis): most frequent cause of aortic valve stenosis age in patients between 15 and 65 of age and often arises in associated with anomalous valves
- bicuspid aortic valve: deformed aortic valves with two functional leaflets or cusps which are often unequal in size (60%); a calcified bicuspid aortic valve is considered the most frequent form of adult aortic valve stenosis
- tricuspid aortic valve: aortic valves with three functional leaflets or cusps which are often unequal in size (30%)
- unicommissural/unicuspid aortic valve: dome-like aortic valve with stenosis at very young age (10%)
- quadricuspid aortic valve (rare)
- congenital (congenital aortic valve stenosis): most frequent cause of aortic valve stenosis age in patients between 15 and 65 of age and often arises in associated with anomalous valves
- subaortic membrane
- idiopathic hypertrophic subaortic stenosis associated with hypertrophic cardiomyopathy
Variable appearance on chest radiographs depending on stage and severity of the disease.
In early disease, the chest radiograph can be entirely normal or it may show dilatation of the ascending aorta with a normal heart size. Differentiation with hypertension can usually be made as in hypertension the entire descending aorta is enlarged.
Late in the disease, the chest radiograph is characterized by cardiac enlargement and features of heart failure - pulmonary venous congestion, pulmonary interstitial/alveolar oedema. At this stage, it is not possible to differentiate aortic stenosis from other causes of heart failure.
A high aortic valve calcification score determined with cardiac CT may indicate severe aortic stenosis, particularly in patients with non-rheumatic acquired calcific aortic valve stenosis 3.
- structural assessment on spin echo MR sequence 1
- bicuspid or unicuspid (rare) aortic valve
- post stenotic dilatation of ascending aorta
- symmetrical left ventricular (LV) hypertrophy wall thickness (>/= 12 mm)
- increased LV mass
- dynamic assessment on cine GRE or b-SSEP 1
- thickened valve leaflets with reduce excursion during systole
- size and extent of the high-velocity jet into the ascending aorta
- hyperdynamic LV contraction in compensated state
Treatment and prognosis
A decision on treatment for aortic stenosis is based on symptoms, left ventricular (LV) dysfunction and coronary artery disease. In symptomatic patient or asymptomatic patients with LV dysfunction, surgical aortic valve replacement is the mainstay of treatment.
Alternatively percutaneous balloon valvuloplasty is indicated in non-calcific aortic valves in young adults or patient with aortic stenosis who are of high anesthetic risk for open heart surgery.
Transcatheter aortic valve implantation (TAVI) is a less-invasive surgical technique for valve replacement in patients with aortic valve stenosis.
The differential of a dilated ascending aorta includes:
- 1. Webb WR, Higgins CB. Thoracic Imaging, Pulmonary And Cardiovascular Radiology. Philadelphia : Lippincott Williams & Wilkins, 2005. (2005) ISBN:078174119X. Read it at Google Books - Find it at Amazon
- 2. Sebastià C, Quiroga S, Boyé R et-al. Aortic stenosis: spectrum of diseases depicted at multisection CT. Radiographics. 2003;23 Spec No : S79-91. doi:10.1148/rg.23si035506 - Pubmed citation
- 3. Laissy JP, Messika-zeitoun D, Serfaty JM et-al. Comprehensive evaluation of preoperative patients with aortic valve stenosis: usefulness of cardiac multidetector computed tomography. Heart. 2007;93 (9): 1121-5. doi:10.1136/hrt.2006.107284 - Free text at pubmed - Pubmed citation
- 4. Koos R, Mahnken AH, Sinha AM et-al. Aortic valve calcification as a marker for aortic stenosis severity: assessment on 16-MDCT. AJR Am J Roentgenol. 2004;183 (6): 1813-8. AJR Am J Roentgenol (full text) - Pubmed citation
- 5. Tutar E, Ekici F, Atalay S et-al. The prevalence of bicuspid aortic valve in newborns by echocardiographic screening. Am. Heart J. 2005;150 (3): 513-5. doi:10.1016/j.ahj.2004.10.036 - Pubmed citation