With the Alizarin Red Stain, I was able to test for calcification in the aortic valves. Now, I needed to measure the functionality of the valves. To do this, I used an ultrasound machine. No, not the one used during pregnancies. I used a specific type of ultrasound: an echocardiogram, which is basically an ultrasound for hearts. The machine sends high-frequency sound waves to produce pictures of the heart. It is able to measure the size and shape of the heart in addition to how well the heart’s chambers and valves are functioning. It uses the Doppler effect to show how well blood flows through the heart. The echocardiogram can even detect blood clots and fluid buildup!
For my experiment, I took all the measurements from the left ventricle (LV) of the heart because it pumps the most blood and it pumps directly into the aorta. I measured the ejection fraction (percentage of blood pumped out by the LV during each contraction) and how much the LV walls contract while pushing out blood. I also took pictures of the aortic valve and aorta with the echocardiogram. In the aorta, I measured the peak velocity of blood and in the aortic valve, I measured the maximum cusp separation during each contraction.
Here is an example of a picture I took with the echocardiogram. In this picture, we can see the left ventricle wall contract as the heart goes through systole and diastole motions:
By comparing the values we see in the pictures I took to standard values of ejection fraction, AO peak velocity, and cusp separation, I can tell how well the valve is working and if there is any stenosis/calcification. Since I took measurements for my control mice and my experimental mice, I was able to use my control mice’s measurements as the standard. I compared the measurements between my control and experimental group and created graphs displaying the differences.
The echocardiogram helped me successfully measure the functionality of the aortic valves, a crucial part in determining whether SIRT6 had any effect on the aortic valves!