Hello again. In the last lecture we discussed Lv size and function. In this lecture we'll be discussing the assessment of RV size and function. The RV is smaller and less powerful in the Lv having only to pump blood a very short distance to lungs. But RV failure is no less fatal than Lv failure and no f cartographic studies complete without an assessment of RV size and function. Let's start with our besides.
As usual, there are a handful of measurements all of which will we will select to RV basal diameter and argument Diana from the vehicle for chamber view. We're gonna slide the probe little medially and tilted so that the RV is centered in view. It is now called an RV focused view. We're going to freeze the image and use the trackball to track back to maximum diagonally Right here, this Frank now use the caliper. To measure these two diameters we have we'll start with the bezel or the diameter. We draw a line across the tricuspid annulus like this, on this end to this end just at the end of my endo cardio border.
This is called the RV basal diameter and it should be no longer than 41 millimeters. The second diameter this caliper again is called the mid RV diameter and is we join the two ends of the RV wall at its middle segment. This is called the argument diameter and it should be no larger than 35 million In any of those is above the upper limit. This indicates the dilated RV. Simple enough. Now, onto RV function.
In the LD we use ejection fraction as a measure for Lv systolic function. In the RV however, we don't use ejection fraction because the unusual geometric shape of the RV Crescent Eric shape makes it really hard to measure accurately. And it's also affected by loading conditions too much. So we use a few other ways. Therefore, and we'll discuss to them here a simply a simple and commonly used way is to measure the taxi or tricuspid, annular plain systolic excursion, some name on the measurement itself is actually much simpler than the name all you have to do is use m modes on the lateral tricuspid annulus. Like so, and mode and position the cursor on the lateral into the truck has been any else and this is this trace you get for ease And then simply use the caliper to measure the excursion from the peak and all the way to the trough in a straight line down.
In this case it's about 22 millimeters. Pepsi should be no lower than 17 millimeters and if it is lower this indicates an impaired RV. As you've probably guessed, Pepsi isn't the most reliable of methods to assess every function and does have some fallacies Most importantly, that it only measures longitudinal contract contractually and not radio contract, but it should do in most cases. However, if you are in doubt and have a decision hanging on RV function, then you can use fractional area change. This fancy name simply means that you measure the 2d area of the visible section of RV insistently and diagonally and divide them. Let's let's switch back to 2d Let's find it's kind of similar to what we did in the Lv with the Simpsons method.
Find a good view with good endo Cardinal definition. And as we did in The Simpsons method, this is good enough and freeze the image track back to good beat Maxim diagonally. Okay. So usually just before tricuspid valve closure Okay, then some machines have a generic area button that can be used to measure 2d area, but if your machine doesn't have that you can always Use mitral valve valve area, so we're going to press Val's and mitral tap area, that's going to give us a cursor. So we just mark the beginning of the annulus here and trace the endo cardio wall. You can see the wall well just use the trackball to animate the image sometimes that can help you see the borders if you weren't previously seeing them clearly.
Okay, here to this end of the nose and press to finalize the measurement. The RV area is about 9.9 centimeter square. Now use it note this write this down and use the trackball to go to system this is this is an axon system right here. Again, press my mitral valve area. And who is the trackball? to trace the endo cardio border of the RV in sisterly.
The area is 4.2. Remember the area and diastole he was for was a 9.9. So if we divide 4.2 by 9.9, we get Oh point four, two, and that's the fractional area change. Normal fractional area change shouldn't fall below 35%. Okay, so we're done with RV size and function. I just want to note that an integral part of assessing the RV is measuring the pulmonary artery pressure, which I've decided to defer to lecture nine, assessing the tricuspid valve the meantime, see you in the next lecture, assessment of the mitral valve