ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Aortic Stenosis: Congenital Aortic Valve Stenosis And Rheumatic Aortic Stenosis

Updated on January 14, 2014

Severe Aortic Stenosis

Stenosis may occur below, at or above the aortic valve. These are termed as subaortic. Valvular and supravalvular stenosis respectively.
Stenosis may occur below, at or above the aortic valve. These are termed as subaortic. Valvular and supravalvular stenosis respectively. | Source

Introduction And Etiology

Obstruction to the outflow tract of the left ventricle constitutes left ventricular outflow tract obstruction. This may comprise of valvar, subvalvar or supravalvar obstructions. Subvalvar obstruction may be fixed or dynamic as is seen in hypertrophic obstructive cardiomyopathy.

Etiology

Though it was thought earlier that rheumatic fever was the commonest cause of aortic valvular stenosis, current evidences is that stenosis developing in congenital bicuspid aortic valve is the most common cause. The commonest causes below the age of 30 years are congenital unicuspid or bicuspid aortic valves. Between 30-70 years, bicuspid aortic valves, rheumatic valvulitis and unicuspid valves account for the majority of cases. Above the age of 70 years, degenerative calcification, bicuspid valves and rheumatic valvulities are the frequent causes.

Stenosis may occur below, at or above the aortic valve. These are termed as subaortic. Valvular and supravalvular stenosis respectively.

Hemodynamic Changes

The aperture of the normal aortic valve is 2.5cm2 . Narrowing of the aperture to 0.75cm2 or less produces severe obstruction to left ventricular ejection and a pressure gradient across the aortic valve develops which may reach 50 mm to even 200 mmHg.
The aperture of the normal aortic valve is 2.5cm2 . Narrowing of the aperture to 0.75cm2 or less produces severe obstruction to left ventricular ejection and a pressure gradient across the aortic valve develops which may reach 50 mm to even 200 mmHg. | Source

Clinical Presentations And Hemodynamic Changes

Congenital aortic valve stenosis

It may be unicuspid or bicuspid, the latter being the commonest. Unicuspid aortic valve is inherently stenotic and is the only type of valvar stenosis present at birth. These patients develop calcification at an unusually young age. Congenital bicuspid aortic valve occurs in about 2% of the general population. The two cusps may be located anteriorly and posteriorly or on the right and left sides.

The bicuspid valve is not inherently stenotic, because of the abnormal opening and closure of the valve cusps, degenerative changes occur which lead on to calcification. Stenosis results mainly from calcification.

Rheumatic aortic stenosis

Active rheumatic endocardities of the aortic valve leads on to thickening of the valve cusps with fusion of both commisures or fusion of a single commisure. This results in varying degrees of narrowing of the aortic valve lumen. Subsequently hemodynamic stress on this abnormal valve produces further degenerative changes and consequent calcification. However, calcification occurs much later than in the case of congenital bicuspid aortic valve. Pure aortic stenosis is rare to develop in rheumatic heart disease. In most cases it is associated with aortic incompetence.

Degenerative calcification of aortic valve

This results from the degeneration and calcification of the tricuspid aortic valve. The calcification is more towards the base of the aortic leaflets and the commisures are free.

Hemodynamic changes

The aperture of the normal aortic valve is 2.5cm2 . Narrowing of the aperture to 0.75cm2 or less produces severe obstruction to left ventricular ejection and a pressure gradient across the aortic valve develops which may reach 50 mm to even 200 mmHg. The left ventricle undergoes concentric hypertrophy which clinically manifests as heaving apex beat. Finally, the left ventricle dilates and fails. When this happens, the force of contraction of the ventricle reduces and the intensity of the murmur diminishes. Due to the fixed cardiac output, syncope results when the subject exerts. The diminishing of the coronary arterial filling may lead to angina pain.

© 2014 Funom Theophilus Makama

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)