Prosthetic heart valve

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Prosthetic heart valves are common. The four valves of the heart may all be surgically replaced. However, the aortic and mitral valves are the most commonly replaced.

Replacements may be tissue or metallic valves, only the latter being visualised on imaging investigations. Sometimes the annulus alone is replaced as seen in annuloplasty rings.

In recent times, aortic valves in select circumstances are being replaced via a transcatheter approach, called a transcatheter aortic valve implantation (TAVI) from a femoral artery approach.

Radiographic features

Evaluation of prosthetic valves often relies on multimodality imaging, including transesophageal echocardiography, transthoracic echocardiography, fluoroscopy, and computed tomography (CT) 3.

Echocardiography

Valve appearance on echocardiography is dependent on the type of valve, which areis generally subdivided into two categories (mechanical and bioprosthetic) with examples as follows 4,5:

  • mechanical valves
    • ball cage valves
      • Starr-Edwards caged ball valve
    • tilting disk valves
      • Bjork-Shiley tilting disk valve
  • bioprosthetic valves
    • homografts
    • heterografts
    • stented
      • Carpentier-Edwards stented aortic valve
    • stentless
      • Biocor stentless aortic valve

Transesophageal echocardiography is the modality of choice to assess the status of a prosthetic heart valve; a baseline study is typically performed after placement, and subsequent studies rely on comparison with this baseline to assess for pathology.

Complications of prosthetic valves 5:
  • obstruction
    • may bemaybe due to thrombus or pannus 4
      • Can be differentiateddifferentiation on MDCT:
        • Pannuspannus appears as a circular or semicircular mass extending from the prosthesis ring. Thrombus appear as an irregular lobulated mass.
        • Pannus, can demonstrate enhancement.
        • Pannus and typically hasshows a significantly higher attenuation, as measured by Hounsfield units (HU). A with a recommended cut-off point of >145 HU has been recommended (sensitivity 88%, specificity 96%).
        • thrombus appears as an irregular lobulated non-enhancing mass
      • thrombogenic obstruction typically occurs with a subtherapeutic INR early after mechanical prosthesis implantation 6
        • ​typically occult to transthoracic echo studies
        • the posterior acoustic shadowing from the valve obscures the typical atrial location of thrombi
        • obstruction due to pannus tends to be a more chronic process, with a slow symptom onset and in older valvular prosthesis
  • infective endocarditis
  • paravalvular regurgitation
  • valve failure (see below)
    • mechanical failure in mechanical valves
    • degeneration of a biological valve
  • haemolytic anaemia: rare, both biological and mechanical valves 7

Severe dysfunction of a prosthetic valve should be suspected when the following parameters are measured 5:

See also

  • -<p><strong>Prosthetic heart valves </strong>are common. The four valves of the heart may all be surgically replaced. However, the <a href="/articles/aortic-valve">aortic</a> and <a href="/articles/mitral-valve">mitral valves</a> are the most commonly replaced.</p><p>Replacements may be tissue or metallic valves, only the latter being visualised on imaging investigations. Sometimes the annulus alone is replaced as seen in <a href="/articles/annuloplasty-rings">annuloplasty rings</a>.</p><p>In recent times, aortic valves in select circumstances are being replaced via a transcatheter approach, called a <a href="/articles/transcatheter-aortic-valve-implantation-tavi-2">transcatheter aortic valve implantation (TAVI)</a> from a femoral artery approach.</p><h4>Radiographic features</h4><p>Evaluation of prosthetic valves often relies on multimodality imaging, including transesophageal echocardiography, transthoracic echocardiography, fluoroscopy, and <a href="/articles/computed-tomography">computed tomography (CT)</a> <sup>3</sup>.</p><h5>Echocardiography</h5><p>Valve appearance on <a href="/articles/transthoracic-echocardiography-views">echocardiography</a> is dependent on the type of valve, which are generally subdivided into two categories (mechanical and bioprosthetic) with examples as follows <sup>4,</sup><sup>5</sup>:</p><ul>
  • +<p><strong>Prosthetic heart valves </strong>are common. The four valves of the heart may all be surgically replaced. However, the <a href="/articles/aortic-valve">aortic</a> and <a href="/articles/mitral-valve">mitral valves</a> are the most commonly replaced.</p><p>Replacements may be tissue or metallic valves, only the latter being visualised on imaging investigations. Sometimes the annulus alone is replaced as seen in <a href="/articles/annuloplasty-rings">annuloplasty rings</a>.</p><p>In recent times, aortic valves in select circumstances are being replaced via a transcatheter approach, called <a href="/articles/transcatheter-aortic-valve-implantation-tavi-2">transcatheter aortic valve implantation (TAVI)</a> from a femoral artery approach.</p><h4>Radiographic features</h4><p>Evaluation of prosthetic valves often relies on multimodality imaging, including transesophageal echocardiography, transthoracic echocardiography, fluoroscopy, and <a href="/articles/computed-tomography">computed tomography (CT)</a> <sup>3</sup>.</p><h5>Echocardiography</h5><p>Valve appearance on <a href="/articles/transthoracic-echocardiography-views">echocardiography</a> is dependent on the type of valve, which is generally subdivided into two categories (mechanical and bioprosthetic) with examples as follows <sup>4,</sup><sup>5</sup>:</p><ul>
  • -<li>obstruction<ul><li>may be due to <a href="/articles/intracardiac-thrombi">thrombus</a> or pannus <sup>4</sup><ul>
  • -<li>Can be differentiated on <a href="/articles/computed-tomography">MDCT</a>:<ul>
  • -<li>Pannus appears as a circular or semicircular mass extending from the prosthesis ring. Thrombus appear as an irregular lobulated mass.</li>
  • -<li>Pannus can demonstrate enhancement.</li>
  • -<li>Pannus typically has a significantly higher attenuation, as measured by <a href="/articles/hounsfield-unit">Hounsfield units (HU)</a>. A cut-off point of &gt;145 HU has been recommended (sensitivity 88%, specificity 96%).</li>
  • +<li>obstruction<ul><li>maybe due to <a href="/articles/intracardiac-thrombi">thrombus</a> or pannus <sup>4</sup><ul>
  • +<li>differentiation on <a href="/articles/computed-tomography">MDCT</a>:<ul>
  • +<li>pannus appears as a circular or semicircular mass extending from the prosthesis ring, can demonstrate enhancement and typically shows a significantly higher attenuation as measured by <a href="/articles/hounsfield-unit">Hounsfield units (HU)</a> with a recommended cut-off point of &gt;145 HU (sensitivity 88%, specificity 96%)</li>
  • +<li>thrombus appears as an irregular lobulated non-enhancing mass</li>
  • -<li>​typically occult to transthoracic studies</li>
  • +<li>​typically occult to transthoracic echo studies</li>
  • -<li>obstruction due to pannus tends to be a more chronic process, with a slow symptom onset and older valvular prosthesis</li>
  • +<li>obstruction due to pannus tends to be a more chronic process, with slow symptom onset and in older valvular prosthesis</li>
  • -<li>dense, triangular <a href="/articles/continuous-wave-doppler">continuous wave Doppler</a> envelope with early peak</li>
  • +<li>dense, triangular <a href="/articles/continuous-wave-doppler">continuous wave Doppler</a> envelope with an early peak</li>

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