 Good morning, and please present this talk on tricuspid valve anatomy. Here are my disclosures. The objectives for my talk are first to review tricuspid valve anatomy, then I will demonstrate how to identify the tricuspid valve leaflets using 2D and 3D transcephageal aquacardiography. I will also touch upon how to identify the leaflets using transcephageal imaging, as sometimes the tricuspid valve leaflets are difficult to identify using transcephageal imaging and a transcephageal probe may be needed. Finally, I will discuss the incremental value of using 3D aquacardiography to image the tricuspid valve. The tricuspid valve is the largest cardiac valve. It has an area between 7 to 9 centimeters squared. It's the most aptly located of all the cardiac valves. It's composed of leaflets, cordytenin I, pavillary muscles, an annulus, as well as the RA and RV myocardium. The tricuspid valve leaflets can actually vary greatly in number. Normal subjects can have between two, three or more leaflets. In the literature, there have been cases of patients with up to six leaflets. If you look at the top row of images, these are 3D transcephageal images of the tricuspid valve, as viewed from the right ventricle. The septum is located at the 6 o'clock position. The anterior leaflet is generally at 3 o'clock and the posterior leaflet around 9 o'clock. If you look at the top leftmost image, you can see that that patient has two leaflets. The middle, three leaflets, and the right has four. If you look at the bottom row, these are pathologic specimens of tricuspid valve leaflets, or tricuspid valve structures. If you look at the left, there are three leaflets identified, septal, posterior, and anterior, and then on the right, you can see that there are four leaflets identified. The tricuspid valve leaflets can actually vary in terms of size. The anterior leaflet tends to be the largest in terms of area, as well as the longest. The posterior leaflet is the shortest circumferentially. It's made of multiple scallops and may not be clearly separated from the anterior leaflet in about 10% of patients. The septal leaflet tends to be the shortest radially. It's also the least mobile, and inserts into the septum about 10 millimeters apically to the septal insertion point of the anterior mitral valve leaflet. If you look at the trans thoracic images on the top row, you can see the anterior, posterior, and septal leaflets as they're identified, as viewed from the right ventricular perspective on the left, the right atrial perspective in the middle. And then there's a cross-sectional showing the septal insertion point of the tricuspid valve leaflet compared to the septal insertion point of the mitral valve leaflet. The tricuspid valve has two distinct papillary muscles. The anterior tends to be the largest. It supports both the anterior and posterior leaflets. There may be a moderator band that joins this papillary muscle. The posterior leaflet is often bipid or triphid, and it supports the posterior and septal leaflets. The septal papillary muscle is actually variable in most patients. It may be absent up to 20% of normal individuals, or it may be present, but then small and multiple. If you look at the top right image, you can see that's a trans-gastric view of the tricuspid valve. You can see the posterior leaflet is located there with that is bipid, and then you can see the anterior papillary muscle, which is single. If you look at the 3D image on the bottom, you can see this is a trans-esophageal, mid-esophageal view, and you can see a moderator band connecting to the anterior papillary muscle. Now the tricuspid valve may have normal as well as aberrant cords. Normal cords are attached at the edge, and accessory cord I can also be seen attached to the septum, free will, and moderator band. Now, if you look at the image in the middle, you can have aberrant short cords that lead to severe tricuspid regurgitation. These cords are generally attached to the body of the leaflet, and they displace the jet from the annular plane into the right ventricle. Now you can also have short non-aberrant cords attached to the edge of the leaflets. Now these cords also can result in tethering and displacement of the jet from the annular plane into the right ventricle. The tricuspid valve annulus is actually D-shaped. Now it's a virtual structure similar to that of the aortic annulus. It's there's not a continuous fibrous ring around the tricuspid annulus. In some areas there's just fat, and it's usually defined as the plane where the leaflet's insert into the area where the right atrium of right ventricle or myocardium meet. The normal annular circumference is about 12 centimeters. The normal annular area is about 11 centimeters squared. Now women tend to have bigger tricuspid valve annuli than men. Now one of the things that's very important to note is the location of the coronary sinus because it plays a very important role in terms of identification of the tricuspid leaflet structures. Now there are two ways that the tricuspid annulus has been broken down for identification purposes. The first is the surgical perspective, which breaks it down into a aortic anterior, posterior, and septal areas. The other is the agricula segmentation, which breaks it down into an anterior septal commissure area, an anterior leaflet area, an anterior posterior commissure area, a posterior leaflet area, as well as the posterior septal commissure area. Now the tricuspid valve annulus is actually very dynamic and changes throughout the cardiac cycle. As you can see, the area changes greatly as well as the perimeter, as well as the circularity during the cardiac cycle. Now you can get a reduction of almost 20% in terms of dimensions and perimeter, as well as the 30% reduction in tricuspid annular area during systole. Now the tricuspid valve is surrounded by other important cardiac structures. As you can see, it's adjacent to the aortic root. This is why if you have an aortic root abscess, you also have to take a look at the tricuspid valve to see that there's not been any spread to affect that valve. It's right next to the mitral valve. Once again, processes that affect the mitral or the tricuspid valve could affect the other valve. Similarly, anteriorly, it's got the pulmonic valves of the LVL flow tract. The tricuspid valve is very close to the conduction system. This is why surgeries involving the tricuspid valve can lead to conduction system abnormalities. So if you look at the left-most image, this is a cross-sectional cut plane through the crux of the heart. You can see the interatrial septum, the septal insertion point, the mitral valve leaflet, the septal insertion of the tricuspid valve leaflet, and then the intraventricular septum. There's a gap between the mitral valve insertion point and the tricuspid valve insertion point, and this gap is the atrial ventricular membranous septum. If you take this cross-sectional image and you rotate it so you're looking at the insertion line of the tricuspid valve, you can see that the AV node sits in this atrial ventricular membranous septum, and then if you take a close up of that node, you can see that it then connects down to the his bundle as well as the left and right bundles. Now when we look at the coronary, we can see that the right coronary actually surrounds three-quarters of the tricuspid valve annulus. So here we have a CT scan showing the tricuspid valve annulus with the right coronary artery and its path, and you can see that it's closer to the tricuspid valve annulus towards the distal part of the coronary as opposed to the origin. Now tricuspid valve, tricuspid regurgitation etiology, most causes of tricuspid regurgitation are actually secondary or functional, and a few are primary. Now secondary causes include left heart disease, right ventricular dysfunction, pulmonary hypertension as well as atrial fibrillation. Primary causes include congenital abnormalities or acquired diseases such as carcinoid, myxomonas valve disease, endocarditis, pacemaker leads, or RV biopsy damage. Now how does tricuspid regurgitation develop? Well regardless of whether or not you have primary, secondary tricuspid regurgitation, they all end up in this final pathway of RV volume overload that leads to more RV and RA dilatation, and then more tricuspid regurgitation. Now how does tricuspid regurgitation develop? Well as you get tricuspid RA and RV dilatation, you get more tricuspid annular dilatation and remodeling the annulus in tricuspid patients with tricuspid regurgitation loses its normal shape and becomes flattened. With tricuspid regurgitation you also get remodeling of the leaflets and cords and papillary muscles become distorted because of the RV changes as well as the RA changes and this causes the papillary muscles to move more laterally as well as medally, as well as get become apoclet displaced, changing the tricuspid valve co-optation. You then get tricuspid regurgitation which leads to more volume overload and then that results in more distortion of the RA and RV dilatation and then the cycle continues. Now how do we identify tricuspid valve anatomy? So traditionally we actually thought that in the RV inflow view as you see on the left image that was the anterior and posterior leaflet and then in the short axis view with the RV inflow and outflow you've got the septal and anterior leaflet. In a four chamber view you're looking at a septal anterior leaflet and then a transgastric you're looking at septal and posterior leaflets. However we know that on 2D imaging we can be wrong about how we're identifying the tricuspid valve anatomy so this is a 3D dataset and it's been cut to show a four chamber view. However on the top four chamber view you're actually cutting through the septal and posterior leaflets whereas on the bottom four chamber view you're actually cutting through the anterior and septal leaflets but both views it'd be very difficult to identify which leaflet is which. So you actually have to look at the structures surrounding tricuspid valve leaflets to make sure you're identifying it correctly. So this I'm showing these pictures even though they were trans thoracic because it clearly demonstrates how to identify leaflets and so then we'll go through the transesophageal imaging next after I cover through this. So if you're in a short axis view of the if you look at the leftmost panel in your look and we're at the short axis view showing the inflow outflow view if you see the tricuspid valve leaflets and you see a single leaflet in this view then you are cutting through the anterior leaflet. If you tilt a little bit so you're once again still in this short axis inflow outflow view and you see two leaflets you're cutting through the anterior and posterior leaflets. If you see three leaflets in the short axis view and you see an LVOT then you're actually going through the septal the anterior and the posterior leaflets. Now in an RV inflow view where you've tilted and you've got the two leaflets you can see if you see a coronary sinus there then you are looking at septal as well as the anterior leaflet. If you actually have closed off so you don't see the coronary sinus then you're looking at the posterior leaflet and the anterior leaflet. Now when you are in a four chamber view it's very hard if you don't have any structures to know where you're looking at it could be the septal and anterior or septal and posterior leaflets. However if you're tilted anteriorly and you see the aortic root or LVL flow tract then you know that you're cutting through the septal and anterior leaflet. If you've tilted back and you see the coronary sinus you know you're cutting through the the septal and posterior leaflets. Now let's move on to transorbital imaging. So in a midisophageal view sometimes you if you can't see your trichocytid valve leaflet you'll have to actually push down and be in a lowisophageal view but in a midisophageal view you're usually looking at the septal and anterior leaflet. If you push down and you see the coronary sinus then you're looking at the posterior and anterior leaflets. Now if you're in a short access view and you just see two leaflets you're usually looking at anterior and posterior leaflets. If you push down and you foreshorten your view and you're not seeing in your lowest off deal then you're looking at septal and anterior leaflet. Now when you're in the transgastric view, the transgastric view is actually the easiest to identify it. If you're in the transgastric view in your short access view you can clearly identify the septum. If you see the liver you know that that's the posterior leaflet and then by default the other one is the anterior leaflet. And then when you cut through with your cross planes and you get a long access view then you can actually know when you're cutting through what you're looking at whether or not you're looking at the anterior posterior leaflet or the interseptile leaflet. Now sometimes if you're doing a deep transgastric view you can see if you see three leaflets and you cut through then you are looking at the anterior and posterior leaflets. And then on the the three leaflets you're seeing are usually the septal anterior and posterior leaflets. Okay so recently there's been a push to better refine how we identify the truck has been leafless beyond what we've been doing already. And part of this comes out of the work that's being done on percutaneous tricuspid valve procedures. Becky Hahn and her group have made this proposal of six different types of tricuspid valve leaflets. If you look here they've got cartoons summarizing each of the types and this is a transesophageal short access view of the tricuspid valve with the septal leaflet in yellow, the posterior leaflet in green, and the anterior leaflet in red. And type one is the traditional tri leaflet valve with a septal anterior and posterior leaflet. The blue dot represents the anterior papillary muscle and this is what they use to divide an anterior from a posterior leaflet. If you look at type two this is the typical two or two leaflet tricuspid valve with a septal and then a fused anterior and posterior leaflet. Type three A has five leaflets with a septal posterior and then the anterior divided by a cleft into an A1 and A2 region. Type three B is five leaflets but here the posterior leaflet is divided into two by P1 and P2. Type three C is where the septal leaflet is actually divided into two so you have an anterior posterior as well as an S1 and an S2. And then type four is a five leaflet tricuspid valve with a septal P1, P2 as well as an A1 and A2. Now they found in their study of consecutive patients undergoing tricuspid valve assessment. The majority of patients have this type one or the traditional tri leaflet tricuspid valve that we know of. However the 30% of patients have a type two B which is where the posterior leaflet is divided by cleft into P1 and P2. Now one of the things as you look at these studies is you realize that 3D echocardiography is very useful for looking at and identifying all three leaflets simultaneously. So if you are doing 2D trans thoracic imaging only about five to 10% of the time will you be able to see all three leaflets in a single image. With trans esophageal imaging about 65 to 70% of the time and that's simply because of the anterior location of the tricuspid valve in the chest making it very far from the probe and making it challenging to obtain that image. Trans thoracic imaging is 3D imaging is very ideal for it because of the location and so about 85 to 90% of the time with trans thoracic 3D imaging you'll identify all three leaflets in the single view. Beyond identifying leaflet morphology you can actually identify the pathology of with 3D echocardiography. So here going from left to right there's an example of a displastic valve with the abnormal cordi. Patient with both mitral as well as tricuspid carcinoid syndrome and you can see the thickened restricted leaflet of the tricuspid valve. A patient with functional tricuspid regurgitation the leaflets are highly mobile but they just do not have co-opt in the center because of the dilatation of the RV and then a patient with pulmonary hypertension. One of the most valuable uses of 3D echocardiography has been the identification of the role of pacemakers in the development of tricuspid regurgitation. So if you look at the image on the left we're sitting in the right ventricle looking up at the valve and you can see that the pacemaker lead is going between the septal and the posterior leaflets and it's in the commissure there so it's not affecting co-optation. You can see that the leaflets come together and there's no gap seen during systole. Now if you look at the image on the right you can see that the pacemaker lead is impinging on the septal leaflet and so during systole there's a gap between the anterior posterior leaflet as well as the septal leaflet because the septal leaflet is unable to move forward to co-opt with the normal anterior posterior leaflets. Now 3D has also improved our understanding of how much we underestimate tricuspid annular measurements from a four chamber view. Typically these are done in the OR to decide whether or not the tricuspid valve should be repaired at the time of valve surgery regardless of the amount of tricuspid regurgitation present. Here you can see it's a four chamber view and on the 3D cut plane that matches that four chamber view you can see that we're actually not cutting at the longest dimension of the tricuspid annulus and so we're underestimating how big it actually is. Now in terms of tricuspid valve acquisition similar to the mitral valve what you want to do is you want to find an imaging plane where you see the tricuspid valve leaflets very well in both cystine and dastille and you also want to make sure it's as perpendicular as you can get through to the beam and then when you acquire a tricuspid valve most of times because it is slightly off axis you will have to use some cropping to show and display the valve nicely. So here we have a patient who has a mitral tricuspid valve disease and we have acquired it in this mitisophageal inflow outflow view and you can and then we've cropped it to align it so we're looking on fast at the tricuspid valve leaflets and you can see both the prolapse and the leaflets as well as the jet that's coming through there. So in summary the tricuspid valve is mainly imaged using echocardiography while transtheroscic is probably slightly better than transesophageal. It is transesophageal is the main modality used especially for interventions landmarks surrounding the tricuspid valve anatomy are very important to ensure accurate leaflet identification and even now we're now moving towards where we're sub-identifying the leaflets and 3D echocardiography vastly improves how we assess the leaflets. Thank you for listening.