 Now, we need to understand a basic difference between axis deviation of the heart and a media transition. So, normally we know that the heart is at a 45 degree axis and there can be a left axis deviation where the axis turns the apex itself turns a little more toward the left or there can be a right axis deviation where the apex goes towards the midline. Now, when you have an axis deviation, we always think of intrinsic cardiac economy. So, to begin with when you have a left axis deviation, there are certain anomalies we think of and when there is a right axis deviation with the line coming in the center, we need to think of some anomalies. Now, why I am showing this is because as compared to axis deviation, mediasonal shift is a different entity in a way. What happens in mediasonal shift is that the heart still points to the left or to the right or to the left and the heart gets shifted to one side. So, if there is a mass here on the right side, the heart, the mediasonum will be shifted to the left but the apex of the heart will still point to the left. And similarly, if there is a large mass on the left side, the entire mediason will be shifted to the right but the apex of the heart will still point towards the left. And why it is important is because axis deviation typically is associated with cardiac economies, whereas mediasonal shift is one of the hallmarks of a thoracic abnormality or thoracic mass and one of the whistle blowers as we have seen it drawn. So, what happens in day-to-day practice is we always don't make it a point to look at lungs, especially getting. So, just like we look at four chambers, RGUT, LBUT, we do not look at lungs, though we are supposed to look at lungs. So, there are some whistle blowers which make us realize that okay, something is wrong in the thorax or in the lung. And the first whistle blower is a mediasonal shift. So, here for example, we can see that the entire mediason is shifted to the left, but the apex of the heart is still pointing to the right, but the apex of the heart is still pointing to the left. And that's a classical mediasonal shift. And this is the first whistle blower that something is wrong in the thorax or in the lung. The second whistle blower is the appearance of the lung. So, typically we said that lungs are slightly more hyper-reflective as compared to the liver. But if the equivalency is significantly different as compared to the liver, that's another clue that something is wrong going wrong in the lungs or in the thorax. And of course, this can be a large hyper-reflective mass as we'll see later on. The third whistle blower are presence of cystic areas within the lungs. So, normally we have uniform appearance of the lungs, but if we see cystic areas such as this, that's the third whistle blower that something is wrong in the lungs or in the thorax. The fourth whistle blower is the position of the diaphragm. So, just to show you that normally if you look at a diaphragm and the respiratory movements, the diaphragm shows a slight convexity towards the chest. And that's a normal appearance. If the diaphragm is flat or if the diaphragm becomes convex towards the diaphragm, that's another whistle blower that something is wrong in the lungs or in the thorax. And lastly, look at the movements of the diaphragm. As I said that more the leaves of the diaphragm should move synchronously. That is very important. If you see a paradoxical movements of diaphragm, as you see here, you can see that one leaflet is going up, the other going down, one coming up, the other going down. That is another whistle blower for a possible thoracic abnormally. Classically, for example, in a diaphragmatic hernia. So, as I said earlier, very often lung abnormalities are picked up, not because we are concentrating on the lungs, but because we see one of these five whistle blowers which makes us aware that something is going wrong.