Level 1 Video Lecture: Valvulopathies

[@eyupkaraer2534]

Thank you very much for very informative and teaching video ❤ We wait excitedly continue videos ☺️

[@isekaidoctor]

excuse me sir, i want to ask something about the AR jet, yes i understand the red is AR jet during diastole means that red towards the probe and also LV. so where does that blue color come from and go to ? cause during diastole, the only blood flow is LA to LV which in this case toward the probe and the color should be red why blue ?, i know blue is away from probe and correct me if i am wrong the probe position is in the upper left side side isnt ? (marked with that long straight line), please correct me, thank you

[@richardfisher9916]

Hi, thanks for the question, which highlights an important point. The convention to demonstrate flow towards the probe as red, and away from the probe as blue, only works for blood which is flowing at relatively low velocities. If we look at the clips in which the AR is demonstrated, the scale is set from +61.6cm/s to -61.6cm/s. When set like this, the software can correctly identify the direction of blood flow, as long as the apparent blood flow velocity is under 61.6cm/s. Once the apparent blood flow velocity exceeds this, the software cannot determine the direction that the blood is travelling, and incorrectly asigns the flow the wrong colour (we term this 'alaising'). We can't just turn up the scale, because Pulsed Wave (PW) Doppler, of which Colour Doppler is one form, has an inherent maximum speed limit. Blood velocity largely depends upon the pressure gradient between where the blood is coming from and where it is going to. Aortic regurgitation is leaving the aorta and going to the LV, in diastole. Let's imagine a situation whereby we have an aortic iastolic pressure of 72mmHg and an LV diastolic pressure of 8mmHg. This gradient, 64mmHg, would be expected to generate a blood velocity of ~400cm/s, far in excess of our scale. Indeed, as a general rule of thumb, most abnormal flow in the heart is high velocity, and so will almost always lead to alaising. 'Normal' flow in the heart tends to be much lower velocity, because a high gradient represents resistance to flow, and the normal heart is designed not to introduce unnecessary resistance. Even these 'normal' lower velocities frequently exceed the Colour Doppler scale, leading to alaising. I have a video which explains just why this happens, which you can see here: kzbin.info/www/bejne/n4W6nalod8l-pposi=4qgysUtcGGhP5_pi

[@isekaidoctor]

@@richardfisher9916 I see, it is a limitation that could be misleading, thank you very much for the explanations sir