 Thank you, Dr. Chan and the ICU Organizing Committee for the opportunity to present here. My name is Azad Mishari. I'm a cardiac anesthesiologist at Toronto General Hospital and I'll be presenting to you today on TD assessment of the aorta and pulmonary artery. All the materials here are under a Creative Commons Attribution License and available at the link here. These are my disclosures. Nothing specific to this presentation. Most of my work is funded by the UHN Foundation and our UHN HHS Anesthesiologist Association. So I'll start by talking about the value of imaging of the aorta and pulmonary artery and routine prior operative exams. We'll look at the 3D anatomy of the aorta and PA and the relationship to the esophagus and the airway which determine our TE windows and we'll visualize the common TE imaging views and we'll look at some pathology specifically atherosclerosis and aortic dissections. So why bother? Well, imaging of the aorta is quite easy. It only involves a few views that are quite easy to conceptualize. It's very fast. It can be done in under a minute. It is cheap. There's no radiation or contrast. It gives you very high quality images in most cases that are every bit as sensitive or specific if not more than seat here in MRI. The main limitation of that being the blind spots which we'll discuss. There's significant diagnostic value in emergencies. The diagnosis of an aortic dissection can be life-saving and of course there's significant prognostic value in evaluation of atherosclerosis in the descending aorta. This is some fairly old but classic data looking at a prior operative stroke after a cabbage and classified by atheroma grade in the descending aorta and patients who had grade 5 atheroma had a nearly 50% risk of stroke at one week. This is a grade 4 had a nearly 10% and then a substantial drop off below that. And this is a grading system that was used in that study and it's a classic grading system that we still use. The grade 1 is normal which is nearly impossible to find in adults. Most adults have at least some to give entomal thickening that would make them a grade 2 so that it requires a smooth entomal outline with thickness under 3 millimeters, any protruding plaques under 5 millimeters will make you a grade 3, anything over 5 millimeters will be a grade 4 and any mobile segments would make it a grade 5, the highest risk category. Atheroma grade in the descending aorta is prognostically useful because atherosclerosis is a systemic disease and significant atheromas in the descending aorta are highly correlated with atheroma dis-disease in the cerebrovascular system and the coronary artery system and elsewhere in your arterial tree. And obviously we have significant means for potentially mitigating at these risks and patients if they're adequately worked up. So how do we do this? So first we'll just have a quick look at the TE windows. This is a posterior view of a 3D model based on a CT. So at the very far back we see the descending aorta coming down. Here in pink we have the esophagus where our TE probe will be sitting, coming down to the stomach. In front of that we have the tracheobronchial tree which is the source of our blind spots and beyond that the vestus of the heart. So you can see that in dark blue the pulmonary artery, in the yellow we have the heart base and in the transparent red and blue the left and right blood volumes. The left main stem bronchus marks the division between the upper esophageal window and the mesosophageal window. The mesosophageal window essentially images the heart through the left atrium and is continuous with the lower esophageal window further down. These are the three main windows that are used in assessing the aorta. The transgastric window is not particularly involved in this assessment. And these are the blind spots. So one blind spot is caused by the main stem bronchi and the carina and it severely limits our ability to image both the distilled ascending aorta further down and the branch PAs. We're actually able to image the right PA to some extent but we're very limited imaging the left PA. In this diagram it looks like the left PA which should actually be fairly visible but in many patients actually that left main stem bronchus is higher up under a significant amount of lymphatic tissue that does not allow ultrasound penetration very well. In the upper esophagus we have a blind spot caused by the trachea which significantly limits our ability to image the distilled arch sorry the proximal arch and distilled ascending aorta in most patients. Just a quick look at the anatomy of the aorta and the PA of course are fairly simple structures. This is the posterior view in the middle anterior view on the left and the left lateral view on the right. We'll focus on the posterior view since that's the view of the TE probe. So the aortic valve initially comes out of the aorta initially comes out of the aortic valve heads off towards the right shoulder then turns midline curves around the airway and the esophagus and descends. The pulmonary artery heads out of the pulmonary valve and goes almost slightly up and straight back and bifurcates with the left pulmonary artery being typically significantly superior to the right pulmonary artery. And here's the same image now with the esophagus and the trachea again interposed. And just to highlight the orientations of the two valves again and the corresponding arteries the long axis of the aortic valve goes from the right humeral head to the apex whereas the long axis of the pulmonary valve is along the mid sagittal plane and goes from the xyphoid to the lower c-spine. So here are the basic TE views for assessing the aorta and the PA. They're in sort of four sets of long and short axis pairs so we have the mid esophageal long and short axis views of the aortic valve we have the mid esophageal ascending aorta long axis and short axis which also show us the PA and long and short axis as well. The upper esophageal arch views and the views of the descending aorta all the way from the upper esophagus down to the lower esophagus. Now while we have eight views here you can actually get most of the information with just four of them by basically keeping your probe at or near zero degrees and going through the entire aorta. So for a screening exam this can be done in under a minute quite easily. Image optimization for aortic imaging especially for the descending aorta involves minimizing the depth. I would recommend keeping two or three centimeters beyond the aorta because in many cases you may see a pleural effusion or lung consolidation that may provide useful information to pair operatively. You can typically use the higher frequency that your probe is capable of because the aorta and the esophagus are very close to each other so ultrasound penetration is usually not a limiting factor and I would recommend using harmonics to minimize cellular artifacts which are especially significant when you have stronger factors like the aortic wall or calcified plaques. So we'll start imaging at the aortic valve and work our way up. So this is the aortic valve short axis at somewhere between 25 and 45 degrees. Of course all these angles are very approximate. You can see in our example here it's actually at 61 degrees. So here we see the aortic valve in short axis, the pulmonic valve in long axis. This is a good view for imaging the coronary arteries at the left main being much easier to see than the RCA but I'll show you some examples. You can also see the left atrium, the right atrium, the interatural septum, the tricuspid valve and the pulmonic valve. And here is a normal example. So again we see the aortic valve in short axis, the pulmonary valve in something close to long axis. And this example of a severely stenotic aortic valve you can see the valve is functionally bicuspid so even that we see a commissure that commissure is not opening between the left and non-coronary cusps we have very thick and leaflet edges with very limited opening. And here we're showing the imaging of the RCA which can be fairly challenging and definitely becomes a lot easier with the use of color Doppler. This of course would be the right coronary cusp here and here is the left main coronary artery coming off the left coronary cusp and you can often even see the bifurcation into the LAD and circumflex quite easily. So next we have the aortic valve long axis view which is obtained from the long axis cut plane. And here you see the aortic root and the proximal ascending aorta. You see the STJ and it's a good view to assess for aneurysms, disactions, functioning of the aortic valve and the aortic insufficiency. So here's a normal example. By pulling the probe up a little bit we obtain the midisophageal ascending aorta views. So in the short axis view shown here you can see the main pulmonary artery and the RPA. Sometimes you're also able to visualize part of the LPA by rotating a little bit left. We have the proximal ascending aorta and next to it would be the SVC. So this is a fairly normal example of this view. So we have the ascending aorta here. You can see the SVC a little bit here. You have the main PA and the right PA. So here again you would see large aneurysms, dissections and potentially if you have any very large thrombi in the pulmonary artery, you may be able to see them here. And this is the long axis view of the ascending aorta from the midisophagus. So here we now see the right pulmonary artery in short axis and the ascending aorta in the long axis. This is a good view for detecting atheromatous disease in the ascending aorta. So here's a relatively normal example again. Sometimes we actually be able to still see the aortic valve in the image but that's not a requirement. As you pull up the probe a bit further you're going to go through the blind spot as you pass behind the left main stem bronchus and going past the blind spot you will then come upon the arch and at zero degrees you will have the aortic arch long axis view. Or you can see at the aortic arch flow any potential dissection or dilation of the aortic arch. And this is a fairly normal example of that with colorful draper on the right. Again you can see that the blood is flowing from the left to the right of the image. At the aortic arch short axis view which also corresponds to the pulmonary artery long axis view is an underappreciated view but potentially quite informative. It gives you a great view of the pulmonary outflow tract and the ascending pa and is one of the best views for making a dopper measurement of the pulmonary valve and the pa velocities. Also by rotating the probe left and right from this position you're potentially able to get some images of the aortic arch vessels depending on where your trachea is located and how large your blind spot is. And in particular you may be able to image the distal arch. So this area over here if you rotate the plane over and this is where the ligamentum arteriosum will be located or where a patent ductus arteriosus would be if the patient has a shunt. This location is also the second most common location for the initiation of a dissection tear because it has some contrary regularity related to the ductus arteriosus and it's also the most common location for a coarctation of the aorta. This is again a relatively normal version of that view the collar dropper on the right and the 2D on the left. And from the same view by rotating left you can begin to image a variable number of the arch vessels in some cases all three of them. It's quite difficult to distinguish which one you're looking at unless you count them as you go back and forth. The left subclavian artery is imaged in the vast majority of patients and we then have the images of the descending aorta which can actually be performed anywhere from the lower esophagus all the way to the upper esophagus and allows us to image nearly the full length of the descending aorta and is often where type B dissections, significant atherosclerosis and aneurysms are diagnosed. We get the corresponding long axis view with a blood flowing from right to left. And here we have the long axis view and a short axis view cut slightly above the valve itself. You can see the valve itself is quite calcified. You have the dissection flaps coming almost to the actual valve leaflets. The true lumen is actually a very small space between these two flaps and they have a potential circumferential false lumen that goes all the way around. And this is the dissection flap in the descending aorta. So erg dissections are commonly classified according to the Stanford classification whose primary purpose is to identify which cases require emergency surgery and which ones can be managed more conservatively and potentially undergo either medical management or elective surgery. About 60% of cases that present are type A dissections which is ones that involve the ascending aorta or the arch and the remaining 30 to 40% are type B which are ones where the pathology is all distal to the left of clavian artery and as such does not pose nearly as high a risk of stroke or cardiac involvement. Diagonal cell type A dissection can obviously be life-saving and a proper pair of these is very important as mortality increases rapidly with any delay as the social diagram of the aortic root that's the aortic valve there and that is the hematoma in the false lumen. There are numerous significant complications of type A dissections including acute aortic insufficiency which can cause complete hemodynamic decompensation, coronary dissection and evulsion, more commonly in the right than the left which can obviously cause infarcts and ischemia, paracardial tamponade in the event of any leakage, aortic rupture which is typically fatal, extension of the dissection into arch vessels which can result in stroke and evulsion of any branches in the descending aorta which can also cause various forms of ischemia from spinal cord ischemia to visceral ischemia. Thank you very much for your attention these are some key references including some guidelines and reviews at the top is a link to this presentation and also links to two presentations by the University of Utah group these are freely available online and they're both excellent lectures that cover more ground than I was able to cover in the 15 minutes today and a big thank you to my lab team and my mentors and thank you again for your attention