Welcome back. Now that you're comfortable enough getting the standard views, it's time to start to actually get some data from these views. The most common question you'll probably need to answer for your patients is whether the Lv systolic function is preserved. before trying to assess Lv systolic function, it's equally important first to assess Lv size, the left ventricle can be normal, it can be dilated, hypertrophied, or both. Small Lv can be observed sometimes in people with very low body weight or in hypovolemic patients. Now there is an abundance an overabundance even of methods used to measure Lv size and function, each with its advantages and shortcomings.
To keep it simple, we're gonna discuss three of the most commonly used methods with varying simplicity and accuracy. The first method is eyeballing which is just looking at the Lv in 2d and using your eyes to gauge its size and function. This is the simplest and quickest method and needless to say this method requires a highly experienced operator with trained eyes and is surprisingly accurate in that case. This method is most commonly used in the emergency setting where there might not might not be time for measurements. And you need questions answered quickly and crudely. And I can't teach you this method of course it comes after seeing a lot of normal impaired hearts.
This This here is an example of an Lv with normal systolic function in the left pair sternum long axis view. You can see how the intercepting posture LD walls both show normal excursion and thickening. This is an impaired Lv and the same view. The difference is easy to spot because this Lv is an extreme state of dysfunction. From this view, I'd give this Lv about 15% ejection fraction. more subtle differences that are of course harder to spot and you can also see here how this Lv is dilated.
Now, there are two caveats you need to keep in mind when using this method. First, keep the depth setting in mind because when judging Lv size, both a normal and a dilated Lv can both be made to fill the screen using Death setting and then consequently look the same to you. Second, never judge Lv function from just one view because in some cases, especially in the presence of regional wall motion abnormalities, and we'll explain those in lecture 11 lV function will look deceivingly good in some views and impaired in others. The next method is called the title method. This method is performed in the first journal long access view using m mode. First, you have to get a good view then I'll press M mode now.
I'll position the cursor so that it cuts the Lv perpendicularly like so. I press freeze to freeze the image You can let go the probe now if you like but practice is to keep your hand in place and use your other hand to take the measurements. For one thing, when you unfreeze the probe, you won't have to get the view all over again. Now to take an item, it's all ultrasound machines and able to echocardiography package will enable you to easily do this in one step. To open the measurement panel look for a button marked measure or analysis or something similar. If you've selected the cardiovascular preset or template as we discussed in lecture three, then all the measurements would show up in the panel will be for the heart.
Now look for a measurement named Lv study or Lv dimensions. Here we can plus analysis. By dimensions, there's a button saying our points we're going to press that on some machine pressing Lv study will give you the cursor start working on some other machines, you have to select one of these dimensions to start with it. We're going to go ahead and start With this button that says IV SD which stands in intervention to set them in diagonally. Once we press that, we're going to get this cursor and we can start moving it. And we can see here in the mo trace that this is diagonally or the ventricle is at its widest and this is Sicily, where where the ventricle is contracted and at its narrowest diameter, we start to move the cursor using the trackball to the upper edge of the intervention color septum in diagonally and press.
Move down a little to the lower edge and press left mouse button again. Then move the button to the lower edge of the Lv posterior wall and diagonally. And here it is, can see it. Don't get confused by all these lines because these two lines are actually the anterior and posterior mitral valve leaflets This is actually the posterior Lv wall. Hope you can see it and then this is the lower edge of the posterior Lv wall. Move again to system D This time, you can see how the highlighted parameter or measurement is now IV s s which stands for intrapreneurial septum insistently press, move all the way down here, press, then move up here.
Press move, lower edge, and press. Ok. So now we're done with the titles method and the ejection fraction displayed is 55.4%. Normal ejection fraction ranges from 52 to 72% in males and 54 to 74% in females and It represents the percentage of blood flow of blood ejected from the ventricle each stroke. The the other values you measure will also be displayed. We have the left ventricular posterior wall thickness insistently, the left ventricular internal diameter insistently, he interprets regular septum thickness insistently.
The left ventricular posterior wall that dimensions diagonally, the left ventricular internal diameter and distally and the interpreter color, septal thickness and diastolic. This is the ejection fraction down here. I placed link to the normal length values of all these parameters and the echocardiography cheat sheet with all the normal values in a PDF page. I placed this in the resources section for this lecture and most of the other lectures. Now using them all is tough Of course, so don't worry too much about it. Just have this list handy with you and practice.
With practice, you'll start memorizing them without noticing, it will notice that the list includes each parameter twice one plane and one divided by or index two, as we say the body surface area. The body surface area is usually calculated by the machine if you type in the patient's weight and height as you discuss the resist custom lecture three, but if it doesn't, you can easily calculate it using this formula. The value of indexing measurements becomes evident in case of patients with extreme bodyweight because you can't expect a 60 kilogram man to have the same lb size as a 150 kilogram man. I mean, the latter might easily have an end diastolic diameter well above the normal range that's in the table. But if you index that to his body surface area and look it up, it's going to be normal. So you really don't have to worry about this on this your patient is really over or underweight and you're getting abnormal measurements that you suspect might just be due to the patient's unusual size.
The titles method is more objective than eyeballing but also has a few caveats. First of all, you have to make sure that you cut the wall perpendicularly like this. Your view is askance or off axis to say, you won't be perpendicular, and your measure dimensions and ejection fraction will be overestimated, or inaccurate. The second thing is that frequently the presence of leaflets Corrie 10 Dini, or speckles of the myocardium can cause the presence of too many lines in the Amal trace, and it becomes difficult to tell which of them you should use for measurement. What I like to do in this case is look at the 2d image above and look at this line over here and try to figure out which structures intersect this line. And, and which of those correspond to which in the trace below.
So when you do that, you can see that this line you for measurement here is actually not the posture of the wall, but the posture, mitral valve leaflet, so the correct line would be right here. The third caveat is that this method only uses a single dimension to extrapolate a 3d volume so it's easy, easy to misjudged systolic function if the one used for measurement isn't representative of the rest of the Lv. Again, this is particularly relevant in the presence of regional diastolic dysfunction. You can see here that the posterior wall isn't moving very well, this patient had an intercepted myocardial infarction. So if I were to use the tie calls method here, a line across the Lv at this point, would underestimate ejection fraction because this segment isn't moving as well as the other segments. Our last method we'll be discussing is called The Simpsons method, and is the most accurate if done correctly, the Simpsons method you need to start out in the APR for chamber view, make sure you have a good view with the clear endo cardio definition.
This is the endo cardio border and don't confuse that with the fiber skeleton of the heart out here. Where you want to see is the endo cardio border. Because we're going to trace that you can increase the depth so that the ventricle fills almost your whole viewport. Sure a couple of beats have passed and press freeze. When you press freeze using the trackball, you can sort of time shift. By move the trackball to the left.
I can go back in time. Select a good diagonally when the ventricle is at its widest this frame right here. Make sure you also have the following system because we're going to need that. Scroll back to diagonally. Okay. There we go.
Now, bring up the measurement thing. Look for something called volumes or by plane. Here we have an E, F and volume button. We're going to press that then we're going to press Simpsons Easy enough and press a triple for chamber diagonally. That's what this stands for. On most machines, you just press the left mouse left trackball button and start tracking the endo cardio border.
But on this particular machine, you mark we press the left trackball button to mark the first end of the annulus and then extend this line and press again and it's going to give us this this skeleton and we need to apply it to the Lv wha of course your game needs to be adjusted so that the end cardio border is visible. We press again and now we can adjust these points by clicking each of them and moving them. I hope the image is not too dark and that you can see the no cardio borders As long as I can, there we go again take this right here this too and just this one there and I press and measure there may not be that same button on your machine. Then I use the trackball to time shift again forward to maximum system, which is this frame and I press a vehicle for chamber s F stands for system and I repeat the same thing again.
Extend the line Mark at the end of the annulus this fix it. Okay, back a little Okay, so the display ejection fraction down here is 52%. For an accurate estimation of Lv function using the Simpsons method you need to repeat this process again in the APR to chamber view so that both planes of the Lv wall are included in the measurement. So we need to get a good april two chamber view. Also with good endo Cardinal border definition. Wait until a couple beats have passed and freeze.
Now we track back To a good beat visible borders making sure we have the following sisterly. Okay sounds as good as any go to maximum diastolic. Press f4 to chamber diagonally and repeat the process just curse then I hope the images is probably enough for you to see and no carniola borders as well as I see it Since they're snowing, in my opinion, I think it's easier just to track with cavity spray. There we go. Now, we'll press and measurement track to maximum sisterly right here and a two CS press that mark the annulus and it's kind of a perfect fit this time. We're gonna go ahead with that Now we have the ejection fraction for the APR two chamber view and we have the ejection fraction VP, which stands for biplane.
This is like an average of or a combination of both APR for chamber and Apex to chamber ejection fractions. There you have it, it takes some work, but it's a lot more reliable. The caveat is that you need a good enough image with excellent my cardio and cardio order definition. we've now reached the end of our lecture, but there are a couple of points that I'd like to note. First of all, what we've been measuring now is called Global Lv function, which means the overall systolic function of the Lv, there's something else called regional Lv function, which means assessing the function of each segment of the Lv one separately to check for coronary artery disease. This will be covered in the metro 11.
The second note is that Lv function is not only systolic function, we also says diastolic Lv function using echo which is a measure for the ability of the heart to relax and accommodate love. And there are many ways to do it. But we're just going to skip diastolic function. For the sake of simplicity, I'm not emphasizing its importance, it's just that it's a bit complicated and at the same time less likely to be relevant to you in the emergency or critical care setting. I'm just mentioning so that you know, it's there and you can look it up if you feel the need to know more. That's all and see you in our next lecture next lecture assessing RV size and function.