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Aortic Dissection

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In this lecture, you'll learn about aortic dissection, how it happens, its echo appearance, and complications including AR, myocardial infarction and branch ischemia. You'll also learn about an additional special view to visualize the whole thoracic aorta: the suprasternal view.

Transcript

Welcome to lecture 16 or course, here a dissection. Early dissection is a devastating complication in hypertension and atherosclerosis of the aorta and presents with a sudden sharp stabbing chest pain that usually radiates the back and migrates down the torso as the dissection progresses. dissection means separation of the layers of the aorta. It takes a bit of imagination to understand what happens in dissection, but we'll try to explain it in simple terms. This is a diagram of the aorta. This is the Lv ot.

This is the Eric valve and these are the roots of the coronaries, which arise from the aorta, just distal to the aortic valve from these pouches called the sinuses of valsalva. This is the root of the brachial artery or the innominate artery and these are the roots of the left common carotid and subclavian arteries. Now the long the aorta like all arteries is composed of three concentric layers, the intima on the inside, the media in the middle and the repetition on the outside. When the area is They used the internet loses some of its elasticity and blood pressure spike can stretch the aorta to a point beyond which the internet can't stretch any further, and it tears the tear happens through all the layers of the aorta. This is called the aortic rupture and rapid fatal examination into the media Steinem occurs. In dissection, however, only the intimate store and the blood under high pressure forces apart the intimate and the medium and fills the space between them.

So now the fact that segment of the aorta, there's the adventitious and the media on the outside intact, the intima on the inside, and there's blood in between the lumen is now narrowed because of the extra layer of blood between the intimate and the media. All of that is not the real problem. The Arabic lumen is wide enough to withstand a lot of narrowing without significant here to hemodynamic effects. The real problem happens when the dissection spreads to involve the ostium of a branch such as the innominate subclavian common carotid. Again, the blood tracks through between their immediate intima. But in this case it can easily narrow their intima lumens to the point of total occlusion sometimes, dissection can spread forward along the aorta as far as the mesenteric and renal arteries and it could also spread backwards to the proximal ascending aorta and disrupt the anatomy of the aortic valve leaflets causing acute regurgitation.

More importantly, it can involve and obstruct the view of the coronaries causing acute myocardial infarction. This is very important to bear in mind because it means that myocardial infarction and early dissection can coexist. And that finding a myocardial infarction and an ECG of a patient presenting with with pain suggestive of dissection does not exclude dissection. Now that you have an idea of what area dissection is, it's time to learn what it looks like on echo. transesophageal echo is about 8% sensitive for detection of aortic dissection, and diagnosis rests on visualizing an intimate flap which is the separated into a layer. This is an intimate flap Looks like on 2d echo.

And sometimes placing color Doppler can help you distinguish the true Eric lumen, in which you can see color flow from the false lumen in which you don't see any code flow. Sometimes there will also be an exit tear back into the lumen and then you can see a jet of blood flowing back into the lumen. In most cases, you'll also notice a dilated aorta. Normal as any aortic diameter should be less than 36 millimeters you can measure it using the caliper. This is an example of a patient with early dissection in which the dissection caused acute Eric regurgitation it smile in this case, though, this is another example of earlier dissection, in which the blood between the intima and the media the blood under the intima flap of thrombosis, and that's why it looks white brighten echogenic in this case, that's actually the ascending aorta is usually most evident in the left person on long axis view proximally.

But if you want to look more distally there's a special view called The Super sternal view, which you get by placing the probe in the external fossa directed downwards with the knob pointing towards 11 o'clock at just your position until you get a view like this. This is the aortic root, the arch and the Aussie of the innominate subclavian common carotid arteries and below is the descending thoracic aorta. You should check all these views for features of air dissection. That's it for this lecture. See you in the next lecture. hypertrophic cardiomyopathy.

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