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Prosthetic Heart Valves

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Transcript

Come to lecture 14 of our course, prosthetic heart valves. Prostate heart valves have become increasingly common and chances are you'll run into patients with prosthetic valve malfunction if you haven't already. It's important that you know how to assess these valves since it's somewhat different from regular valves. This is especially important for the upcoming lecture about infective endocarditis since it's an important cause of prosthetic valve dysfunction. The most common kinds of prosthetic valves you're likely to run into are the following First time is a metallic by leaflet valve. Let's explore its structure a little bit.

This fuzzy ring at the edge is called the sealing ring and this is what the surgeon uses to suture the valve to the heart wall. This metal rim is called the flange and these are the leaflets which open and close on these two hinges. This is called a bio prosthetic valve in which the leaflets are made from bovine or porcine pericardium These are supposed to be more physiological than metallic valves. This is a valve which is used in tavor or transcatheter aortic valve replacement. This is an example of a pair of certain long axis view of a patient who has two prosthetic valves in the aortic position. And in the mitral position where you can see the two leaflets opening and closing.

These two leaflets are vitally metallic valves. You can observe here how prosthetic valves by the nature of their metallic rings cast these long trails that we call acoustic shadows, which make the visualizations visualization of structures lying behind them, rather difficult. For us to examine our function is usually due to formation of a thrombus, a penis or a vegetation, which is infection on the valve leading to narrowing of the valve area, restriction of leaflet motion or the heatsinks of the valve which means attachment of the suit Rain from the surrounding Hartwall thrown by usually form acutely or subacute in the setting of inadequate anticoagulation, while pennis is formed insidiously over years, irrespective of anticoagulation status. vegetations from Southern Caribbean are usually accompanied by fever, or other features infective endocarditis. Unfortunately, Echo is not reliable for accurate differentiation between these masses and clinical correlation is more useful for that purpose.

And in many cases, even visualization of the obstructing mass by echo transthoracic echo is not possible due to the bright acoustic shadows cast by the valve and the only evidence of their existence is gradual or acute increase in valve gradients or a new valve regurgitation. prosthetic valve malfunction is commonly discovered accidentally hearing a routine echo but other times the patient will present to you with a complaint like new onset this near palpitations chest pain. Sometimes the patient will present with syncope or eventually Talk. Some of the more observant patients will even complain that they can no longer he'll appear the valve click in case of metallic valves. And this is complaint you should always take very seriously. Let's start with assessing prosthetic valves first gnosis note that prosthetic dowser naturally no narrower than made of valves.

In most cases you can visualize prosthetic valve leaflets, by to the echo transthoracic and check they can both open and close normally, for the mitral valve position the best This is best seen in the short axis mitral valve level. This is an example and you can see how both leaflets are opening and closing well in the shape of V. This is an example of the pair sternal long axis view and you can again see both leaflets. This is the valve in April for chamber view. These are the two leaflets For the aortic valve, the short axis greatness a little frequently visualized leaflets if you fail to adequately, adequately visualize leaflet motion using Echo, and you can use T or fluoroscopy to visualize the valve. This is an example of the patient with the two prosthetic prosthetic by leaflet valves and mitral and aortic valves seeing using fluoroscopy side by side and you can see both leaflets both valves opening and closing.

This is an example of a malfunctioning prosthetic mitral valve by leaflet metallic valve. And you can see here that one leaf that is moving well while the other leaf is completely immobile. This is what we call a stuck leaflet. This is the same valve and pear strung along axis again, you can see how on leaf This is not moving at all. quantification of prosthetic valve stenosis is done using the philosophy and the ingredients similar to Normal valves, except that the normal values are higher than native valves, and also vary according to the type and size of valve. You can also measure valve area using the continued continuity equation for early valves and use pressure halftime for mitral and tricuspid valves.

Similar to the normal valves. Again, the nominal value values are different, I think included link to a normal values table in the resources section. You can use the link I've placed in the resources section. And there's also there's this nifty app called auto calc. It's free, available for both Android and iOS. It's by the British society of echocardiography, and it has all the normal values for cardiac chambers and valves, including prosthetic valves, as well as a bunch of useful calculators.

I've also placed a link to it in the resources section of this lecture. This is an example of continuous Doppler tracing of a mitral valve prosthetic mitral valve that is malfunctioning with only clicks Stuck in the closed position and you can see how the peak velocity and gradients are abnormally high. If you can see both leaflets opening and closing adequately, that are getting abnormally high gradients by Doppler, then you have two possibilities. The first one is a hyper dynamic circulation, which can be due to mark tachycardia, anemia, Pregnancy fire toxic causes, or valve regurgitation, and keep that in mind because we'll come back to it later. The second cause is what we call prosthesis patient mismatch which simply means that the valve implanted is too small for the patient, especially if the patient has gained a lot of weight since the implantation. Now let's move on to regurgitation.

Prosthetic valves have a normal degree of regurgitation, which we call closure volume. This is a T view of a prosthetic mitral valve and you can see this small jet, a regurgitation. This is what we call closure volume and it's a small amount of blood that manages to escape through the valve before the valve is fully closed. There are usually two jets but we can only see one at this view. Anything more than this normal closure volume is abnormal prosthetic valve regurgitation can also happen between the valve and and the heart law. So between the suing ring and the heart wall, in which case it's called a pair of valves hardly any degree of pair value or leak is abnormal.

This is a prosthetic aortic valve and the arrow indicates the jet of the aortic pair value or leak. This is the same patient Sr paraspinal short axis view. And again, the arrow indicates the jet and you can easily see that the jet is outside the valve. It's not through the valve the regurgitation happens between the bout suturing and the myocardium. severity regurgitation is estimated using the same criteria has phenomenal valves. With the added difficulty that prosthetic valves always cast bright acoustics.

Shadows, as we said that make it hard to visualize anything beyond them. In the case of the mitral valve in the April 14 Review specifically, this makes appreciation of regurgitation troublesome. That's why you have to know when to suspect it even if you don't see it. Remember, when we listed the causes of increased gradients in spite of normally moving leaflets, I told you to pay special attention to valve regurgitation. The first thing you should suspect in the case of elevated gradients in the absence of an obvious cause is regurgitation, and that same prosthetic valve, so elevated gradients, together with a normal estimated area or pressure halftime should prompt you to look for significant prosthetic regurgitation. So that's one clue.

In addition, severe prosthetic valve regurgitation, especially when parallel healer can cause significant hemolysis with all its clinical and lab features, so finding that in a prosthetic valve patient should also prompt you to look for hidden regurgitation. This is an example of a patient with a prosthetic aortic valve and you can see how the gradients are elevated. This patient Doesn't have your externals it doesn't have prosthetic aortic stenosis or malfunction. This is actually the same patient with the aortic pear value or leak. leak is not well visible in this view because it's an eccentric jet. But the clue here is the elevated gradients.

When we kept looking, we found the pair of alveolar leak jet. Finally, seeing obvious valve hastens in the form of a rocking valve on 2d will definitely indicate the presence of a severe pair of alveolar regurgitation. You can see here how the prosthetic valve almost completely detaches. From the heart wall is swinging back and forth what he called rocking prosthetic valve he senses an extremely serious condition needing urgent surgical replacement of the valve. That's it for this lecture. In the next lecture, we'll be discussing infective endocarditis.

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