 In today's tutorial, we will look at the addition of color Doppler while doing the fetal cardiac assessment. Is it a value addition tool? And if it is, then how do we use it and why do we use it while doing the fetal cardiac assessment? So fetal cardiac assessment can be a part of anomaly scan. It can be a dedicated fetal echo. So the guidelines, there are different guidelines according to if you're doing it as a cardiac screening or if you're doing it as a part of dedicated fetal echo. So as a part of dedicated fetal echo, all the guidelines will say that use of color Doppler is mandatory. But as a part of 18 to 20 weeks obstetrics scan, the guidelines have not implemented the use of color Doppler. They say that only if the cardiac anomaly is suspected, then you can use the color Doppler as an additional tool. So is it helpful then to use it as an adjunct in all the low risk population patients? It's a dilemma. What is the scenario in India? What is our goal? Is it giving a precise diagnosis of a cardiac anomaly or is it just spotting a cardiac anomaly and referring these patients elsewhere? There are different sets of rules in different parts of India where you are practicing. It depends on if the facilities for a dedicated fetal echo is available or not. Facilities for the tertiary care units dealing with major CHD is available or not. So if you are doing a fetal cardiac screening, an unbalanced four chamber view or a common AV valve or an abnormal position of the heart, these are the findings which are mainly related to a grayscale imaging. Unilateral perfusion of one ventricle, the AV insufficiency, the retrograde flow in one of the vessels in the three vessel view, these are the findings related to the use of color Doppler. So overriding vessel, the parallel vessels and one great vessel in the three vessel view might be detected on a grayscale. However, these abnormalities are probably also easier to spot using a color Doppler. So we will just see one or two examples of this. So if you see this heart, the spine is posterior, this is an 18 weeks anomaly scan and you feel that there is the cavity of the LV is really very small. Of course, it is not a very good section, it is little obliquity as you can make out from the multiple ribs which are seen there. But it appears as if the cavity in the left ventricle is really small. But then if you are trying to see on color Doppler the three vessel view, it shows a forward flow in the aorta as you can see here. So you are wondering whether LALV is small, so whether it is hypoplastic. On color Doppler, the inflow is not very well demonstrated but you can see a forward flow in the aorta. So you know there has to be a cavity of the LV which is receiving blood and then you make the patient wait for some time and then you start seeing it. Though here it is not so clear but you can see two inflows and you know here the grayscale image may not be very good but then the two inflows are definitely seen. So then I will think whether it is a co-actation or I will look at the pulmonary veins if they are training into the left atrium or not and try to see whether it is the pulmonary venous drainage problem. Now this four chamber view apparently looks normal but then when I come to the three vessel trachea view, I know that this pulmonary is very small and though of course the black and white imaging is helping me here, you can see that there is aliasing which is coming somewhere here and it is not even coming at the level of the tricuspid valves here. So this is typically an Epstein's anomaly, there is a regurgitation which is seen a little apically and then if you go back to this you know that you know there is a apical insertion of this valve, it is you know quite low placed, the septal leaflet is quite low placed and this is typically an Epstein's anomaly. This is another anomaly scan and if you see the four chamber view is normal, the three vessel trachea view is okay and then when you are doing the color study, when you add the color Doppler, you start seeing that there is some aliasing in that section in the aorta. So then if you do the spectral Doppler examination, you will realize that there is a very high velocity across the aorta which is 323 centimeters per second. So this is an aortic stenosis and then it may evolve into hypoplastic left arm or critical aortic stenosis and things like that. Then of course there are certain anomalies like ARSA, the operant rights of playbinatory or the vascular rings which are better demonstrated on the color Doppler on the use of color Doppler. So how do we optimize the color Doppler? How do we use the color Doppler by doing the fetal cardiac assessment? It all depends on the technique or the physics of the color Doppler. Size of the color box should be very small just occupying the fetal heart. The velocity scale has to be adjusted. If you are looking at the high velocity structures like to inflows or to outflows, the velocity scale can be on the higher side. But if you're trying to look at the pulmonary veins, you will have to really lower down the velocity scale. The color filter is the high filter is recommended. Color persistence is low color persistence is recommended. So if you go to the cardiac presets in your presets, all these things are actually set by the application specialist. But one should know how these settings are helpful in fetal cardiac assessment. Color again is if you are looking at the low velocity structures like the IVC, SVC or the pulmonary veins or you are trying to look at the ARSA, then the velocity and the color gain velocity can be low color gain can be little high. Color balance or the right priority is something which is always set at maximum while doing the color, while doing the fetal echo. The right priority is something like adding the color over your black and white or your gray scale image again, which is kept at a higher values while doing the fetal echo. So if you see here, this color box is very wide, you know, you don't really need so much of the information here. And what it causes is drop in the frame rate because this is too much of an area of the color frame. If you narrow the color box, look at the frame rate, it has improved, it has become 24 hertz and the overall the frame rate and overall sharpness or crispness of the image will increase. Now here the velocity scale is very low and that's why the color is bleeding. If you increase the velocity scale, you are seeing the better color filling but still the septum is not really very well defined. There is still some bleeding here. So then if you adjust it still higher, now you will see only the ventricular cavity is filled. Now if you make it still higher, what happens is you will not really see the color filling the entire ventricular cavity, then even that is also not very good. So then again you have to make the adjustments depending on which structure you are seeing and then once you see that, you can see both the inflows and both the outflows, the LBOT, the RVOT. In fact, you can see the SVC color and in fact the azagus vein which is coming here like this. So all these structures are optimally visualized, both inflows, both outflows, the three vessel drug view and everything is seen very well. So when you use color Doppler in fetal eco, again it is the same way how you do in your black and white imaging. You use it as a four chamber view at the outflow tracks, the three vessel drug view and for the demonstration of aortic and the ductile arches. So this will be the two inflows. This is the LBOT, this is the RVOT, this is a three vessel drug view. The SVC will be, the color will be in red in the opposite direction. When your velocity scale is little high to see these other cardiac structures, the SVC will not pick up the color. You will have to lower your PRF or the velocity scale to see that. Then this is the ductile arch, the bider arch and this is the aortic arch. You will see the three branching vessels also arising from the aortic arch. Then if you are trying to see the pulmonary veins, as I said, you will have to lower the PRF. Showing two pulmonary veins is mandatory. In fact, you see here both the pulmonary veins on the left side and one on the right side. This is the video of that and you can see the pulmonary veins filling up there. One basic principle what you need to remember is that to see the color, the color direction has to be parallel to your ultrasound beam. This is your ultrasound beam which is coming like this and that is why when the flow, the pulmonary veins are going in this direction like this vertically. So they will be picked up better on this section as they are parallel to the intonation of the ultrasound beam. So what is the clinical usefulness of the doing the color Doppler? It gives you the blood flow information, the flow across the valves, the smaller structures like narrow pulmonary artery or shunt across the VSTs. It gives you the direction of the blood flow, especially in a three vessel tachyabue. If it is an anti-grade or retrograde flow, it can detect some unexpected blood flow events like regurgitation, a turbulent flow across the aorta like we saw in our previous case or it may be in the pulmonary artery or it may be just a ventricle or coronary fistulas which will be seen in certain conditions like PA, IVS, intact ventricular septum and then when you're wondering what this condition is, if you put the color on and if you see these fistulas, your diagnosis gets extended by that. The demonstration of smaller vessels, the pulmonary veins, the abnormal vessels like napkas, the LSVC or dilated ozygous vein or the RSA. So all these structures will be seen while using only the color Doppler. So clinical usefulness is again there in all three sections, a four chamber, the outflow track view and three vessel tachyabue. So it will give you a supportive diagnostic clue on a color Doppler. So we will see on these different sections what are the clues on color Doppler and what is the diagnosis in these conditions. From this book of Abu Ahmed then Rabishavi, in fact there are more conditions described and more kind of conditions given in that book. So if you have a color flow sign and a possible cardiac defect, so in four chamber view, if you see two inflows with small connection across the septum, it is a ventricular septal defect. If you see two inflows with discrepant ventricular width, most of the times, commonly it is coactation of the outer. If you rule that out, then maybe some other conditions and then you start looking for that. Two AV valves are draining into one ventricle or if you see only one inflow, it is either double inlet ventricle or it may be a univentricle. If you see one common AV valve or a Y shaped kind of the inflow, it is in the AVST, that is it your ventricular septal defects. If you see only right sided inflow, it is hypoplastic left hand or mitral atresia. If you see only left sided inflow, then it is tricuspid atresia or a PIVS. So now if you come to the outflow tracks and use a color Doppler to see any abnormalities, if you see a turbulent flow across the aortic valve in five chamber view, it is a vulvular aortic stenosis. If you see no flow across the aortic valve, it is in the hypoplastic left hand syndrome. If you see VSD with overriding aortic root, then of course there is a big differential TOF or PAVSD or TORV or absent pulmonary valve syndrome or a common arterial tongue. If you see a large vessel arising from the left ventricle with VSD again, it is a cat. If you come to a three vessel tachyabue, then there are a lot of permutation combinations possible. It may be an integrated flow in the aorta and PA, but both these vessels are dilated and showing some turbulent flow. It is because of the pulmonary stenosis. Same way, if you see it in the aorta, it is because of the aortic stenosis. If you see in a narrow pulmonary artery, then it is top or TORV or in obstynes anomaly. If you see narrow aortic arch, it is co-optation. If you see no aortic arch continuity that is interrupted aortic arch and if you see a retrograde flow that is in the aorta, it is HLHS. If you see anti-grade flow but in the aorta, but retrograde in the pulmonary artery, then it is PAVSD or PIVS. These differential diagnosis, we will be learning more about it in our upcoming conference in the VTEL EcoMaster class. So in the end to summarize, we will say that a routine use of color Doppler makes the examiner more confident with this technique and improves its accurate and reliable use in difficult scanning conditions. It also helps in, in fact, in OB's patients when, you know, your 2D imaging sometimes is not very good. It is definitely a time saving tool. We routinely assess the fetal art using the color Doppler at all gestational ages from 12 weeks to 40 weeks. In fact, the color Doppler is of tremendous value in the early anomaly scan where we try, where we rely most of the times on seeing 2 inflows and 2 outflows forming OB at that 12 weeks empty scan time. So the key points when using the color Doppler are that color optimization is critical in order to display the best interpretable images. Smaller the color box, the higher the frame rate. The color presets for flow across the 4 measure valves, you have to have the high velocity scales, high filter, low gain, low color persistence. And the color presets for pulmonary veins or the smaller vessels, you have a low PRF, low filter, high gain or high persistence. And by and large, the inflows view and the 3VT view are the most informative planes while using a color Doppler scan.