TSRA Podcast: Congenital - Tetralogy of Fallot (Michael Cain & Matthew Stone)

[music] Welcome to this edition of the The Rasek Surgery Resident Association's podcast. The opinions expressed in this podcast are provided for teaching purposes only and should not be applied directly to patient care. [music] Alright, so first talk about a neonatal presentation. You're called to the neonatal intensive care unit. There's a 38-week gestational age baby that has prenatal diagnosis of a VSD with concern for some outflow tract obstruction, potentially tetrology. They empirically placed the kid on prostaglanins due to sinusis at birth. Outgars were 8-9, the kids now stable on a little blow by oxygen, but have called you to evaluate. Okay, so I'd start by going and seeing evaluating the patient. I'd want to obtain a complete history, both a maternal fetal history as well as pregnancy history as well as a family history of any congenital defects. And then you've kind of outlined the early neonatal, perinatal course here as well, but any additional things that have come up from a hemodynamic instability standpoint as well. Yeah, no abnormalities. The mom had an unabentful pregnancy, was compliant with prenatal therapy, had regular follow-ups. No part children, no history of congenital heart disease. They've obtained a chest x-ray, which shows some decreased pulmonary gaskillature and an EKG, which is normal. The exception of some mild right ventricular hypertrophy, and they're at the bedside now working on the echo. So what are some things that you're going to talk to them about? So I'd want to talk to them about it as part of the detailed echo cardiogram to get a good assessment of the bi-vitricular function for this child. I'd want to have an assessment of any degree of health full track obstructions since that was more questionable, as well as the directionality on the shunt through the known VSD. And then if we are able to, I'd also like to get a good assessment of the pulmonary arteries and their size as well, and then see how this response has been to the prosicland infusion so far. Yeah, there's a small duct that is left to right, and the PAs look of reasonable size as these scores are within normal limits. The bi-vitricular function is normal. There's a very large, what's described as an anterior malalignment VSD. So there's overriding of the aorta on the septum, and the conus is resulting in some infindibular obstruction, however it's mild. I tell you it's about two meters per second. The pulmonary bowel anulus is -2.5 z-score, and your shunt is currently left to right. There's mild TR, no other abnormalities. Okay, so I think it's an overall fairly reassuring echocardiogram, albeit consistent with tetrology. With a relatively normal size pulmonary valve anulus and normal pulmonary arteries, I'd expect this child to be able to wean off prostituclandin with some therapy over the next day or so. I'd proceed to work on that with the ultimate goal of letting him gain weight and medically manage his physiology for undertaking a definitive repair of his tetrology. Okay, so we'll change this scenario slightly, and they have the same kid, same history, presents five days of life with similar birth history. They've weaned off prostituclandins, and the kid's oxygen saturation is less than 80%. There are two liters, nasolcanulum, and pulmonary bowel anulus is around z-score of -3, and the gradient across the sub-alvarian bowel bar regions is approaching 4 meters per second. I think that this is more consistent with a child who's struggling from a pulmonary blood flow standpoint with a stenotic pulmonary valve. On nasolcanula, not not intubated, but one could be more likely to need a repair earlier rather than the other child we were talking about. So, you talked with the cardiologists, and you both agreed that it failure to wean from prostituclandins as an indication for surgery. How are you going to counsel the parents about your plan for the war? For the first child, this kid clearly needs an operation. He has an oxygen requirement that's increasing after the wean across the glannins, and he has no other contraindications to go into the OR. Head ultrasound is normal, and he's not premature. So, I counsel the patient and his family that with a small anulus of that size, it's unlikely that we'd be able to preserve his bowel within his repair of his tetralogy, and so that would include his repair, would include an infantibular patch extending under the proximal main PA. I counsel them about the risk of heart block with repair of the BSD. I counsel them on the risk of a residual VSD after repair, and then I'd also counsel them about the long-term effects of doing a trans-annual patch, which would be the potential for intervention with a pulmonary valve replacement in the future. So, the parents' hermit agreement with surgery, the cardiologist agrees, however, he comes back to you, and he says that he's concerned that the branch pulmonary arteries look small, and they're around as e-score of minus two, and ask what your thoughts are on complete repair versus shunt in the setting of small PAs. I think what I'd discuss with them and the family as well is that particularly in such a young child, the pulmonary arteries are fairly compliant, and so it's fairly likely that if we restore normal pulmonary blood flow that they would descend and be normal, that can be confirmed with haggard eye labors in the OR, which can give us an assessment of how compliant they are. A pulmonary artery plasticity is unlikely, although we'd have to assess for that in the OR based on the sensitivity. Okay, great. So, you go to the operating room, how are you going to set the case up, and what do you plan to do? Yeah, so, so, the immune-sertotomy, we would do a bio-capital cannulation. I think there are multiple approaches. One is to do the muscular resection and VSD closure through the right age room, but most familiar with doing it through the infant and the vet patch, particularly in a child who's going to have a trans-annual patch as well. So, we would use a bio-capital cannulation, myocipal thermo, and rest the child. Preoperatively, I want to make sure that we have a good assessment of the coronary anatomy. I suppose in this child who needs to go to the OR regardless, we can assess that based on the surface anatomy as well, but it'd be important to know whether or not their left-and-tier descending artery comes off of the right side, right coronary or not, as that would change the preoperative plan. All right, so you get in the operating room, you inspect the coronary rates, and your preoperative echo show that there was a clear left-main bi-procation into circumflexion LED. There's a prominent colonel branch off your right coronary, but you agree on your intraoperative inspection that there's clearly a LED going into the apex off the left coronary. And so, you give your dose of an integrate cardiac plezia, you open the right atrium, you put your vent through the septum, and then you open the infindibulum, and you see complex muscle, bumbedol, hypertrophy. How are you going to sort the anatomy out? I think that when I want to ensure that I don't resect the portion of the tricuspid subbalbioapparitis and the supporting structures, so I want to trace that back to the tricuspid cord A to identify important, like the moderator band, and then resect. just the. the. um. or divide the muscle which is tethering the RVO-T to open that off for track. Okay, so you open it up, you pass a hangar down through the infantibulum into the right-pinch boil, you feel that you've relieved the majority of the obstruction and there's a large antiremaul alignment and ventricular septal defect that's pretty standard anatomy and you close that with a Gore-Tex patch. Then you transition to looking at the pulmonary valve and the kids about five kilos now. And looking at the pulmonary valve, you size it to around four millimeters in diameter. You choose to open up the PA and look at it from the top. What are the things that you're going to be looking at to determine whether you save the valve or do a full tracing of your patch? So I think the leaflet anatomy would be important if you know if it's bicuspid tricuspidlyphlets and then the extent of whether a like a commage erotomy will relieve the proportion of the obstruction. That would be one thing that would be a potential for this child but it's a fairly small on the lower end. I think that if you know if I had any concern I wouldn't have too much hesitation about just doing a transanular patch and believing the obstruction primarily is the goal. Yeah, the measurements that you're getting are pretty consistent with the pre-operative echo show and your z-score was around my three. So with all that you decided to do a transanular patch. You could across the valve which opens up the annulus and extend that into your supervalver incision. What are you going to patch your outflow with? Traditionally we've used core matrix as a patch of the transanular patch as opposed to cortex. Something which incorporates a little bit more scar. Okay great, you start your weenop bypassed, your dear left heart, you take your clamp off and you're in sinus rhythm. The synographer tells you that there is a moderate size residual of intricular septal defect up near the aortic valve annulus. How are you going to evaluate that? What are your criteria to go back on bypass? I think that the first thing to do would be that we've already given an echo synographer, an ecosanographer, an assessment of it, but to do a shunt fraction and see what the QPDQS is for this. And see if it's a sign of being based on that. Okay, so you do a shunt fraction and it's two to one. And that's where it's kind of right on the borderline, but I think that in that child it probably would be worth loud to repair that residual BSD. Okay, all right. So you go back on, you repair the BSD, you come off bypass, and you relieve the gradient through the right intricular outflow track. So we'll go back to the first child who recovered from their neonatal resuscitation. They have favorable anatomy, but a borderline, pulmonary valve, they spend their first week of life in the hospital, their oxygen saturation are in the high 80s, not on oxygen. When are you going to tell the parents that you'd like to do the repair? I think ideally, you know, in my training, I've been taught to repair these around six months of age. There's some people talk about repair and slightly later. But in a child who's otherwise growing well, a definitive repair would be at six month of age, would be sufficient for growth. Okay. So generally, I would say probably four to six weeks for true ten anatomy. I think you'd be able to have more BSD physiology without any outflow track destruction than you can wait a little bit longer. So you tell them four to six weeks. And unfortunately, the child represents, rather unpredictably, at three weeks of age, and is cyanotic, satirin, the sixties in the emergency department. There's evidence of profound cyanosis and the chest x-ray demonstrates decreased pulmonary blood flow. The echocardiogram tells you that there's been a fairly rapid progression of the infantibular hypertrophy, such as the gradients now, about four to five meters per second, and there's clearly sub-dolbar obstruction. So based with what you diagnose as an acute test spell, how are you going to treat that? I think that the first thing to do, or to ensure that we have adequate oxygenation by intubating the child, providing better saturation, bond resuscitate if there are any issues with hypotension. But his physiology is also going to be one of the right to left-- or sorry, right to left shunt. And so increasing his systemic venous resistance will be helpful, so some alpha agents will be helpful for him as well. Any other pharmacologic modalities? I think beta-hockey is also helpful in these children as well. So you put the kid on procranolol, you give them an alpha agonist, you sedate them, you put them on oxygen, and you stabilize the child. He improves from a metabolic standpoint and the systemic oxygen delivery. However, it's clear that he needs a rather emergent operative intervention to relieve his alpha-attract obstruction, and you decide to do a complete repair. I think we'll move on now to-- after a complete repair, a new patient that you operated on as a child presents at age 25 had a transannular patch in infancy and has done quite well. There's no residual shunts, intercardiac shunts. There's good ol' v-function. There's mildly reduced r-v-function, and there's evidence of both severe pulmonary valve insufficiency as you would anticipate in some prolongation of their QRS on EKG, and they present to you because of exercise intolerance and decreased aerobic capacity. Okay. So, yeah, I've discussed the kind of timing and the duration of these symptoms, any other symptoms of heart failure or congestion. I think it'd be important to know if there's any things that are-- any other things that are considered with the right-sided dysfunction, such as liver dysfunction for this young patient as well. And then I talked to them about the indications for a pulmonary valve replacement and somebody who's having symptomatic severe pulmonary valve regurgitation. Okay. So, in consultation with your cardiologist, you all discussed that there are MRI-derived criteria for pulmonary valve replacement and you get an MRI. The right ventricular endostolic volume index is 180. The right ventricular endostolic index is around 100. The r-v-function is estimated about 40%, the regurgitation fraction of the valve is 35%. And unfortunately, in consultation with your interventional colleagues, the pulmonary valve annual is too large for percutaneous approach for repair. So, you counsel your patient that there is an indication for pulmonary valve replacement and if you could just walk me through what the operation entails. So, I think an important part of the pre-appered assessment is to assess the spacing between the coronary arteries and the pulmonary-- the pulmonary artery as well as part of the pre-appered of the planning. But for this patient, it would be-- the plan would be for a tissue valve replacement in the pulmonary position, reoperative sternotomy. Reoperative CT angiogram would be helpful to assess reentry. And so, I don't want that as well. Or in kind of a high risk reentry, a performer, you know, redo-median sternotomy. a bio-cable cannulation with snares. And, you know, you can perform these without arresting the heart, but I think that in otherwise normal left ventricular function, I would probably arrest the heart to make sure that there's no question about the quality of stitches and, you know, closeness to the coronaries and that era, plenary groove. Are there any things on the echo that you would be particularly concerned about that we'd push you in one direction or the other whether to arrest the heart? I think closeness of the coronaries in that era, plenary groove would be one primary, or it would certainly be one thing that would sway me towards arresting the heart. If he has a residual atrial level shunt, I'd arrest the heart. There are oftentimes we leave behind an atrial level shunt which closes, but I don't know that. And there's be the primary things. Good. Good. Okay. Okay. Yeah, you did a nice job. I think those are the main, I think, scenarios that are helpful to familiarize yourself with tetralogy. And, you know, when we think about tetralogy, I think grouping them into probably three groups is the best way to think about it anatomically and physiologically, one being tetralogy without any right ventricular alphloge tract obstruction. So more BSD physiology, but a TET type BSD. Oftentimes those are referred to as pink TETs. Then, tetralogy with pulmonary stenosis, which is what we focused on in this discussion. And then, tetralogy with pulmonary atreasia, which brings in the potential for able to pulmonary collateral and a rather complex surgical management strategy. So, just in recap going over a couple of things, you did a nice job walking through the decision algorithm with your echo and evaluating your pulmonary bowel annualized size. As we discussed here and as you appropriately chose, the discipline is certainly moving towards complete repair even in impency. The traditional practices have oftentimes entertained utilizing either a shunt or a right ventricular alphloge tract patch to palliate children until a complete repair, but as our experience has grown with neonatal surgery, we as a discipline have moved towards more complete TET repairs in impency. I think having conceptual understanding of shunt and RVOT patching as potential palliative steps are particularly beneficial in children that have contraindications to complete repair, particularly those that might have contraindication of cardiac pulmonary bypass and that may be able to undergo a shunt without being on pump. Generally, if the pulmonary valve annulus is greater than a z-score of minus two, then that pulmonary valve is likely to be able to be preserved with commissure otamies. The majority of pulmonary valves in tetralogy are by cuspid, and you can open up the valve sufficiently. However, the gray area is really in between a minus two and minus three z-score and then less than a minus three generally nearly all those children required a transannular patch. I would probably use paracardium, either autologous or bovine, as you know, you're really trying not to have scar and you want redundancy in your patch, such that, you know, really any patch material likely works, but I think the traditional experience is to use paracardium to preserve long-term patency. And you appropriately alluded to PA size. You know, we know that the pulmonary arteries branch PAs are very compliant in the unates, and so I would not let a pulmonary artery z-score preoperatively dictate the need for either pulmonary branch pulmonary augmentation or shunt. I think sizing the PA's intraoperatively is a very appropriate step, and the majority of these children will have larger PA's once flow is restored to them. The residual VSD, I think, is an important point because tetrology children have protected pulmonary vascular and therefore their PBR is going to be low, so after the repair, they handle residual shunt very poorly. They'll have much more flow through a small shunt as a result of that, and they're used to a chronic pressure load rather than a chronic volume load, and so making sure that you relieve both the obstruction, but also so the shunt is an important factor, particularly in neonatal tetraperes. You did a nice job managing the tet spell, I think, sedation, decreasing the right to left shunt and trying to shift the shunt to left to right by alpha-agonism, proprano law. Really, the mechanism of proprano law is debated, but there's thought to be an effect of relaxing the infantibular muscle with beta-agonism. And then the indications for pulmonary bowel replacement, we generally get MRIs in all of these young adults and older adults in determining when their candidacy for pulmonary bowel replacement, and the volumetric indices are really a primary driver, so riventricular and diastolic volume index greater than generally 150 and then an insustolic volume index greater than 80. Decreased RV function, so the cutoff 47%, but any decrease in function should prompt evaluation of the pulmonary bowel and increase in the QRS duration and then a decrease in the aerobic capacity, so less than 70% of the O2 max, would be all the indications for pulmonary bowel replacement. A lot of these are moving towards trans catheter therapies, but still having knowledge of surgical pulmonary bowel replacement is critical. And these patients are particularly hard to reduce sternotomy, so I would just encourage you and all these patients to have a good understanding of the funeral vascular chair so that you're ready to initiate bypass through the groin, so oftentimes the patch or conduit, if they've had a conduit in the past, is scarred to the chest. And these are important things to consider. One other special consideration that we alluded to, but then touch on, was the potential for a LED off the right when you're faced with that. The preparation or the technique would be to place an RV to PA conduit over the LED, so you make an infantibular incision as you did. Resector muscle bundle, closure BSD, and then have what would be a dual supply to the main pulmonary artery, so you would build a conduit from your infantibular incision over the LED off the right and onto the main pulmonary artery. But overall, very nice job.