Trans-Catheter Interventions: New Horizons in Medical and Surgical Fontan...

So Brian's going to talk to us next about what he does in in the cath lab to help these patients. Thanks, Dr. Velman. So this talk is not intended to be a broad array of all things interventional amongst the Fontaine population. I'd like to go through a particular case and and a little bit. About the thought process within that case, one or two other brief examples, and then keep moving through today's agenda. This is really intended to introduce the topic of trans catheter interventions now that we've talked a lot about using both invasive and noninvasive tools to assess the physiology and the hemodynamics of patients with Fontan circulation. This first case is a nine year old female with hypoplastic left heart syndrome who had mitral stenosis and aortic atresia, who underwent typical stage palliation to get to a lateral tunnel penetrated Fontan procedure. At 8 years of age, she developed Fontan associated plastic bronchitis with progressive increase in cast frequency following the initial onset. She underwent an evasive evaluation at another institution which revealed elevated Fontian pressure and elevated transpulmonary gradients. She did not undergo any transcaheter interventions, she was started on Aldactone, inhaled steroids, aerosolized TPA to try and break down existing casts, as well as sildenafil because of the increased transpulmonary gradient and pulmonary vascular resistance that we've talked about so much already today. She had no change in her cast frequency following uh these interventions and medical therapies. She was thus referred to us for uh further evaluation including catheterization with plans for intervention. As a brief review of Fontan associated plastic bronchitis, this is a rare but really devastating complication of the Fontan circulation. It occurs in less than 2% of patients with Fontan circulation. It's characterized by protinaceous lymphatic effluent into the tracheal bronchial tree where there's connections between the lymphatic circulation and the airway. With evaporation, with breathing of the water contents, the characteristic fibrinous airway casts remain behind and may be expectorated in whole or in part and are typically beautiful examples of the tracheobronchial tree. They don't come with a ruler Um In this patient we brought to the cath lab and measured a mean PA and fontan pressure of 19 with a wedge pressure of 12, suggestive of a persistently elevated transpulmonary gradient even on PD5 inhibitor therapy. Um, the right ventricular and aortic pressure didn't reflect any obstruction and the baseline EDP was 11. We did perform a fluid challenge which the the diastolic pressure rose to about 15 after uh after fluid. The baseline QPQS was 0.73 to 1, suggesting the presence of right to left shunt. The systemic cardiac output was normal at 2.9 L per minute per meter squared, and the pulmonary vascular resistance was elevated for a patient with single ventricle circulation on PD5 inhibitor, but all that said, not so atypical for many patients who present with the complications of Fontan circulation. These were the baseline angiograms showing a nice lateral tunnel fontan. The fenestration has clearly closed spontaneously. There's not much right to left shunseen at the level of the conduit. Branch PAs are unobstructed. Flow in general through the circulation is a bit sluggish, which isn't so uncommon in an intubated patient. The other thing you'll note is the presence of bilateral femoral venous occlusion, so this catheterization is performed via access through the through the liver. Given the presence of elevated pressures, elevated transpulmonar gradient despite therapies and persistent gas production, we set about making a fenestration to increase right to left shunting, to augment cardiac output and try and create a little bit of a pressure pop off for that elevated central venous pressure. In the next slide you'll see the presence of a transesophageal echo to give us some guidance. It's a transepal needle which has been straightened because of the course from the hepatic vein, and we'll use that the transeptal needle to get across the lateral tunnel fontan and into the left atrium, which you'll see a little bit of a dye injection in the left atrium through the transepinal needle. A wire will be passed and then a balloon will be used in order to dilate this space. And we'll use the balloon as a dilator to gain access to the left atrium with our sheath in order to place a stent uh to finish the fenestration creation. Here's some stills showing you an angiogram of the right upper pulmonary vein with our sheath demonstrating sheath position, and then there's a stent that is overlying the lateral tunnel into the atrium, which when dilated will create a communication for a right fluff shunt or fenestration creation. In our hands we've chosen to use covered stents for this procedure, not because of risk of dye leakage or extravasation or injury. We found the incidence of fenestration, thrombosis or stenosis early after the procedure, in short and mid-term follow-up to be very high with the bare metal stents, presumably from tissue and vagination through the cells of the stent and tissue factor exposure to blood, even on anticoagulation, thrombosis is pretty common. So this is a covered stent that's going in, you can see it inflated, and then the angiogram after the stent's been placed demonstrates a nice fenestration in the lateral tunnel with right to left shunt. Now, even good procedures don't always mean much. Cardiac output improved with the fenestration, Croatian warfarin was initiated. The aortic saturation fell into the low 80s. Of course, with each cast episode, desaturations occurred into the 60s and 70s. The cast episodes did not improve, and ultimately the patient was referred for heart transplant evaluation. She underwent transplant about 4 months after the fenestration creation and is now doing quite well. So I think the lesson from this case is one can do a good intervention in a complex population doesn't always mean you're going to change the ultimate clinical outcome, but there are clearly roles for more, more limited or minimally invasive therapies in the management of these otherwise complex patients. Couple of additional therapies that we can offer, uh, this is a patient who has uh Fontan procedure. This is an extra cardiac Fontan you can see on the right, the picture in the SPC demonstrates a mild left pulmonary artery hypoplasia with otherwise very nice right and left lungs with nice arborization throughout the lung fields. In the image on the right, the extra cardiac conduit, which was placed at 20 or 22 millimeters, has shrunk down and now measures something like 14 or 15 millimeters, creating obstruction to flow for a population, of course, that has a very high incidence of liver-related pathologies, as Dr. Veltman will speak to later today. Having obstruction in the inferior limb of the fontan can be a real problem. It only serves to augment venous hypertension, and of course, like the other things we've talked about today, a resting absence of gradient does not rule out the presence of hemodynamically meaningful obstruction. So in this case we set about treating both the left pulmonary artery. Here's an angiogram selectively in the left pulmonary artery demonstrating some hypoplasia. You can see the pigtail catheter in fact is widening the left pulmonary artery, suggesting it's a compliant lesion as it's under some tension and maybe some compression from the kneeo aorta. Angiogram to the right is after stent placement in the left pulmonary artery revealing relief of the hypoplasia. The stent's been tailored proximately so there's not metal hanging out in the lumen, creating a thrombostonitis uh approximately. We then place stents across the extra cardiac conduit, and these are the final angiograms demonstrating relief of conduit obstruction, relief of LPA obstruction, and an opportunity to normalize hemodynamics in as much as possible for this patient with Fontan circulation. Another example, this is a Fontan patient who was desaturated. Clearly there's evidence of a left SVC, the coronary sinus, that has recurred, uh, or at least uh developed and hadn't been noticed previously. So one can put a vascular plug in this to occlude the LSVC, and I think the more important finding in this case actually isn't the persistent LSVC of the coronary sinus, but is the fact that the left denominator vein is rather obstructed. It's gonna go back and show that one more time. That left anominative vein, of course, is nearby to where the thoracic duct inserts and all of the lymphatic circulation gets back into the systemic circulation and can create a real opportunity for this patient to present with either plastic bronchitis or protein losing enteropathy, two really important diagnoses associated with very adverse clinical outcomes that have been shown increasingly, especially by the group from Philadelphia, to be associated with lymphatic pathology. So in this case, uh, the LSVC therapy was probably the lesser of the two therapies. We performed a cutting balloon and standard angioplasty techniques to try and resuscitate the left denominative vein and restore normal venous flow. This is after restoration of the left denominative vein, there's improved flow into the the hemi baffle within the fontan circulation. I'm going to stop there and go through some brief conclusions, open it up. I didn't really want this to be a smorgasbord of anything we can do, but just to open up the conversation of trans catheter approaches to therapies. I think we can offer a wide range of approaches to improving both anatomic substrate as well as palliating physiologic intolerances in the Fontaine circulation. What I've termed secondary palliations, meaning palliation of a palliation, the Font circuit, have limitations. They may not offer cure. They may not even offer substantial benefits. Sometimes we're not able to test the hypothesis until we actually perform the intervention. And it's very important, if not critical, to understand that the approach to trans catheter interventions must be taken from a multi disciplinary perspective. We don't practice what we do in a silo. Therapies have both medical and surgical considerations to future therapies, to the need for anticoagulation, and other aspects of therapy must be undertaken with a team-based approach with healthy conversation beforehand and even during procedures, as many. The folks in our room know I've been known to call almost everybody in this room with questions in the middle of the cases as we go about our decision making. It's not as simple as, OK, there's an obstruction, we're going to treat the obstruction. Everything we do can have sequelae, and it's really important to make sure that the multiple disciplines we use to care for these patients all understand and appreciate the implications of decision making and therapies. I'm gonna stop there and see if there's questions from the group or the audience and otherwise offer us an opportunity to catch up with the agenda, but. Brian, thanks. Uh, uh, um, one of the things that, you know, we see not infrequently is patients end up in adult life with fontan conduits, whether it's in the lateral tunnel or more commonly actually in the extracardiacs, that the diameter of the conduit is generally small. And, you know, and we've both seen conduits of 1416 millimeters, uh, in size. You know, how aggressive do you think we ought to be? And I'd like to open up this discussion, uh, you know, in treating patients like that, you know, should we, uh, uh, in an anticipatory fashion, go in and deal with those conduits, dilate them up to their original size, stent them up to that size? Should we take the ones that were 14 or 14 to 16 millimeters in their original size? Should we electively replace those ones? I, I think this is a good question, and I think I certainly don't know the answer to it. Um, from a technical standpoint, treating an extra cardiac conduit that has shrunk, so to speak, um, Tuesday, today is Thursday, so Tuesday I took a patient who had an 18 millimeter extra cardiac conduit that measured 8 millimeters to the catheter. And we dilated instead of that. I think there's there's patients where it symptomatic. Yeah, patient was symptomatic with exercise intolerance, but many of our patients have exercise intolerance, and there's clearly nothing that we did to demonstrate that the exercise tolerance was going to be causal from that, nor improve from that intervention. I think it's incumbent upon us to do the testing to demonstrate that, and I think you offer one opportunity to do the testing is if there's a way to get. You know, leg venous pressure or pic venous pressure. And arm venous pressure with exercise and demonstrate a discrepancy between those two with a gradient across the conduit, that's really meaningful data. I think the surrogate for that would be to show that there's increasing, let's say, liver stiffness to suggest that that's a clinically meaningful obstruction. I think those deserve therapy. The good news is the therapy is pretty easy to do. Bad news is if they're not on anticoagulation, they ought to be on anticoagulation after that because clearly stent and conduit equals thrombo. gen ic behavior substrate and that in and of itself is not benign, you know, a 12 year old young man being on Coumadin is not free and so we don't yet have perfect answers to our questions, but I think it's a great question. I think having seen many of these patients grow up and face symptoms increasing through their teenage years, I personally think it's worth being aggressive when there's anatomic deficiencies we'll call them within the circuit, but I think we don't know everything very clearly. The question is. Uh, Daniel Oliveira says we have a question from Brazil about how do you conduct this fluid testing. Can you explain a little more about it? Yeah, Danielle or Daniel, thank you very much for the question. It's a great question. Um, we published our protocol. It's in Hart in maybe 2015 or 201616. Uh, Avrin, Constantin Avrin, one of our fellows wrote this up, A V E R I N, so you can find that, um, but it's very simple. We give. 15 ccs per kilo with no limit of fluid volume uh rapidly via our central axis, we give it in about 2 minutes and then they get a timer started. Every patient has 5 minutes from the end of fluid challenge until we measure our repeat hemodynamic runs. They got 5 minutes to sort of equilibrate that fluid and then and then they get a repeat measurement. There are some limitations if they have overt diastolic dysfunction, which we define as. Baseline EDP arresting EDP of greater than 15, we don't do it since they don't need to look for occult problems. They already have the overt problem and if they have a baseline Fontan pressure greater than 18 and or repeated hospitalizations with heart failure to get volume off, we don't go ahead and give the 15 ccs per kilo because I think they've already manifest problems, um, but apart from that, it's a pretty simple approach that we do with every Fontain patient on the cath lab who meets those criteria. Thanks for the question. Brian, can you, uh, safely, uh, increase the size of an extra cardiac cortex, uh, tube conduit? Uh, above the size of it was at original implantation. So how high can you go? Great question. So can we increase the diameter beyond the nominal diameter of a Gore-Tex tube? Um, there is increasing experience with this in homographs and contegra conduits in right ventricular pulmonary artery position. There's less experience in the lateral tunnel in the extrac cardiac conduit position. Um, uh, we know that we can safely take cortex tubes to at least 110% of their nominal diameter. Beyond that, I think there's a bit of risk. That stated, I think the risk is probably pretty subtle. So if it's an 18 millimeter tube taken to 22 millimeters, for example, I think that's a pretty subtle risk, and we certainly have covered stents to easily place within that range. To protect ourselves, there's always risk at the anastomosis where it's hard to necessarily cover that should a problem arise because hepatic vein enters very close or something, for example, but I have not yet seen an avulsion of a Gore-Tex tube with moderate dilation of that structure. So years and years ago I, I took balloons and I took Gore-Tex tubes and I blew them up, uh. You can take them up to about 110%. The problem is that whatever it is, their stiffness constant is very high and you, you cannot generate enough pressure in the balloon. To stretch the cortex much more than about 110%, so I mean I, I think the risk of rupture is actually very low too, right, so I think the risk is low, but you, you're about 100, and you, you'll get a 10, if it's 20 m you might get it up to 22, it's very difficult to get it any higher than that. The good news is there are, there are few patients who have an undersized tube at placement and, and really require augmentation of the nominal diameter. I mean, yeah, but it's not uncommon for them to have sort of an, you can put it in a large conduit and it'll have sort of, it'll. It'll have an elliptical shape when you're done and, and so it's it was also a series of homografts being put in as extra cardio conduits and you can crack them up and they get, they get highly calcified. I think the important thing for When we approach this as interventionalists as recognizing that this is a a three dimensional structure as you just alluded to, they're not circular, and if a 22 millimeter tube measures 17 in the frontal plane, it often measures 25 in the lateral plane, and we don't touch that. The cross sectional area is just fine. It's important that there's a true stenosis, not just a non-circular shape of it, for us to want to treat it. All right.