Assessing Cardiac Valves - The Aortic Valve

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Transcript

Welcome to lecture eight assessing the aortic valve. In the previous lecture, we learned how to assess the mitral valve regurgitation and stenosis. Assessment. The aortic valve is pretty similar with a few differences that we'll discuss. We can see the aortic valve and the pair of stern along axis view, the pair of sternal short axis view great puzzle level where we can see the three cusps forming sort of an inverted Mercedes Benz sign on close. You can also see it in the APR five chamber and the typical three chamber views.

As usual, the first step in the assessment of the aortic valve is to examine the valve in 2d. You should be able to see to the three leaflets in the pair sternal long axis view with a central closure line in the middle of the aorta. That is diseases which affect the aortic valve are more or less the same as The ones which affect the mitral valve. So we have rheumatic heart disease sclera calcific, heart disease, and also prolapse. In addition to another common disorder which is called bicuspid. aortic valve.

A bicuspid aortic valve is a common congenital anomaly that can lead to early valve stenosis regurgitation and two ascending aortic aneurysms. And the person is the person on long axis, we can observe an eccentric closure line so the closure line of valve is not in the middle, but is eccentric towards one or the other sides. It's very evident in the pair sternal short axis view rate vessel level where you can see that the valve has only two leaflets and opens in the shape of an ellipsoid and closes in the shape of a line. That's freeze the image and sisterly on the back was open, and you can see how the opening of the valve is ellipsoid instead of triangular. This valve is well opening however and not synoptic. Let's take a look at a different pathology.

This is an example of a valve with heavy sclera calcific disease, it's immediately obvious that the leaflets are thicken with again chunks of calcium deposits. You can also see how liquid mobility is restricted and the opening is quite small. Let's have a look and short access. Same changes are clearly visible. Let's have a look in a typical five chamber view, ignore the color. Just look at the aortic valve right here.

You can see how the leaflets are thinking calcified and almost not moving. You can immediately realize that this valve is stenotic The next step is to use color Doppler to visualize blood flow across the aortic valve. This is an example of a rather low quality image of vascular calcific aortic valve, you can see the abnormal jet like flow across the valving system indicating stenosis. This is another color Doppler flow in a typical five chambered view showing an abnormal jet direction back into the Lv, signifying aortic regurgitation. So again, we have both stenosis and regurgitation and we will know how to determine the severity. Let's Let's start with regurgitation.

Assessing severity regurgitation for the aortic valve also has several methods and we will be discussing three of them. You're already familiar with the first one which is Vienna contract them. The second one is the ratio of jet width to Lv ot width and third one is pressure halftime. We're going to discuss all of those now. This example is a case of mild aortic regurgitation. Let's take this example.

This is this is moderate aortic regurgitation. First of all, let's freeze the image and meet via saline and where the regurgitating jet is most visible. Let's measure being a contract at the same way we measured in a contract for mitral regurgitation, across the narrowest part of the jet or the neck of the jet easily enough to have the same kind of values as mitral regurgitation. So below 0.3 is mild AR, above 0.6 is severe AR and in between is moderate. So this one is moderate AR because the Vienna contractor is about 4.5 centimeters. Let's take this example.

And let's apply this The second method, Jet with to LVT with let's first measure the LVT was Lv ot diameter, I'm going to still image without color to make it easier for you at first and then go back to the one with color. lv ot diameter is measured at the basis of the aortic valve leaflets. Go to analysis dimensions Lv ot diameter, and you'll get a cursor and use that to draw a line across the Lv ot between the basis of the two leaflets right there. You can use the Zoom knob if necessary to enlarge the image and see exactly where you're placing your cursor. Now let's go back to that color image. So again, we're going to measure the LVT here at the basis of the two leaflets, and then we use the caliper to measure the jet width along the same line.

So say the elbow T is two centimeters or 20 millimeters and the jet width is open six centimeters. So we divide the jet By the Lv ot diameter and we get a ratio. In this case it's Oh point three. ratio below 0.25 is my AR ratio between one to five and oh point six, five is moderate AR, and a ratio above 0.65 is consistent with severe AR. The third method we'll discuss is pressure halftime. Remember how we use that and mitral stenosis to calculate the valve area?

Well in the aortic valve, we use it to estimate regurgitation severity. Go to the typical fact chamber view with color Doppler on Place the cursor through the aortic valve. Always have colored dots or online we do it so that you can see the jet and align the cursor properly with it. CW and pw Doppler must always be well aligned with the flowing question or you get underestimated values, a CW now. Now we can use the baseline knob to make sure the entire AR envelope is visible. That's the one Above the baseline because it's flow towards the probe.

Now we go to here the valve, ar pressure halftime or AI in this case for air insufficiency pressure halftime, we press that I get a cursor. Now let's pick an envelope with a well defined border that's still with this one. mark the beginning of the slope and draw a line parallel or in line with the slope line and mark the end. And now the pressure halftime is displayed. A pressure halftime below 200 milliseconds is strongly indicative of severe our pressure halftime above 500 is mild and obviously in between is moderate. Notice how we always have several methods of doing everything because none of those methods is perfect and you always have to use several methods and correlate their results to be sure As we did for the mitral valve, we will explain how the presence of severe er bears upon your patients management.

As an MMR high blood pressure increases regurgitation, so that needs to be very well controlled. Secondly, you should avoid heart rate lowering drugs because a lower heart rate, heart rate means that prolong diastolic and a prolonged isolate allows the ventricular pressure to drop to near zero pressures, making it easier for regurgitated blood flow back to the Lv. final point before we move on to stenosis, remember, in the mitral valve where we discussed functional mitral regurgitation? Well, the aortic valve can also have functional regurgitation. In this case, you can see that the valve leaflets look normal. But the regurgitation that you see here, mild as it is, is because of aortic root dilatation.

You can see toward the end of the cycle in the aorta opens up that it's abnormally dilated. This patient has an aortic aneurysm and The translation of the aortic annulus interferes with normal leaflets closure and leads to regurgitation. Now let's move on to stenosis. As usual. Again, the methods have a lot in common with those of the mitral valve. First, let's look at pressure ratings from the age of five chamber view.

Direct the cursor through the opening of the aortic valve and press continuous wave Doppler. CW is an example trace vz image. You can use the baseline or any scale knobs you have to adjust the image accordingly. Now go to the measurement pane or analysis pane valves, aortic valve, the aortic valve trace or aortic valve VTi. That's press that get the cursor. Of course, he already got flow is from the ventricle to the atrium to the yada yada so it's flow away from the probe so it's below the baseline.

So this is the aortic valve society flow, place your cursor at the start of the envelope and trace the envelope all the way to where it needs the baseline again. Press again and you have the peak and the ingredients and peak velocity. Normal peak velocity is below 2.5 meters per second here, it's an insane you're four seconds so that makes it about oh point nine meters per second. So it's normal peak velocity above for a severe Eretz gnosis while below three is mild and in between is moderate. The next parameter is ingredient, above 40 millimeters of mercury or 15. Europe is severe by below 25 millimeters of mercury is mild with moderate in between again, you memorize these numbers with practice, you don't have to sit down and memorize them now just keep them handy.

And the resources section for every lecture I'll be including the normal values is a printable PDF. Now that we look at gradients, we want to estimate the value area. Unfortunately, planting a tree of the aortic valve in transthoracic echo is not reliable, so we're going to resort to a different method on the continuity equation. machine will do it for you, as usual, but it's like takes several parameters. The good news is we already have two of them. We have the VLT diameter we just measured and we have the aortic valve VTi that we just measured right now.

All that we're missing is the Lv Lv ot VTi. We measure this just like they are on VTi but this time with pulse wave Doppler, and with the sample volume place just proximal to the eclipse. So we'll switch back to 2d, the same session we did use for the aortic valve VTi We now press P W. Also please press the image go to analysis aortic valve and select Lv ot VTi is this possible there and there we have the aortic valve area estimated to be 3.12 centimeter square. The normal area is three to four centimeter square, and area below one centimeter square severe stenosis above 1.5 is mild and in between is moderate. An important caveat to keep in mind in the presence of reduced Lv systolic function. gradients are unreliable because The impaired Lv cannot generate enough pressure so the transfer alveolar gradients are lower than normal and you can't use them to judge stenosis severity.

But instead you should calculate the valve area by continuity equation. For patients with severe errors, you need to do almost the opposite of what you did in AR. You need to bring the heart rate down so that the prolong diagonally enables the Lv to become well filled and the Frank Starling law can kick in resulting in more powerful contraction, which can overcome the obstruction. You also need to avoid valve dilating agents because the increase in cardiac output required to offset the decreased peripheral vascular resistance will be blunted by the obstruction, putting your patient at risk of dangerous syncope. This concludes our lecture. In the next lecture, we'll be discussing assessment of the tricuspid valve and pulmonary artery pressure.

See you there.

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