Congenital Heart Disease for the Pediatric Surgeon Part 1: Acyanotic heart disease

Hi, I'm Rod Gerardo, research resident at Cincinnati Children's Hospital Medical Center. And today, we're going to change gears. We're going to talk about something a little close to the chest, congenital heart disease. All right, that was uh that was a bad joke. I'm sorry about that. But don't worry, we're not going to get into the weeds about it for the pediatric cardiothoracic surgeon. No, no, no, no. This is just going to be the basics that every PE surgeon should know. And to help us out, we're going to hear from Dr. Colleen Pater. She's a cardiologist at Cincinnati Children's Hospital Medical Center. Okay, let's start with some basics. What's the normal blood flow in fetal circulation? So the oxygenated blood uh comes from mom through the ductus uh venosus and goes um primarily streams through the right atrium. The um oxygenated blood um aims to go across the um PFO to the left atrium into the left ventricle. The right ventricle um gets 65% or pumps 65% of the fetal blood and the left ventricle only pumps 35% of it. Uh the reason is that primarily deoxygenated blood is going out um to the body, but then the oxygenated blood coming directly from mom is going uh from the left ventricle directly to the brain. And all that physiology changes as soon as the baby is born. When the baby comes out and immediately starts breathing oxygen, um that high oxygen pressure uh causes a massive uh pulmonary vasodilation, uh which ends up sending a lot more of the deoxygenated blood directly to the lungs, uh that can do oxygenation and send it back um to the body. Uh this as a result the high P2 um causes PDA constriction. Um and then all of the blood going back to the left side of the heart um causes increased left atrial pressure which closes um the PFO. Um the PVR does drop quite precipitously over the first 12 to 24 hours of life. All right, so the most common congenital heart diseases overall are right to left shunts. Think like a VSD. But the most common cyanotic heart disease, that's tetrology of fallo. And there are some genetic associations to keep in mind too. For example, atrio ventricular septal defects are associated with trisome 21. And 22 Q11 deletions are associated with conal defects. Thanks to advances in imaging techniques, we can now diagnose a lot of these patients with prenatal ultrasound. But for the rest of the patients, we can rely on the newborn screening tool. There's a nice fancy algorithm. We don't have to get into the details, but know that a child who's born, who potentially has a congenital heart disease, usually the newborn screening tool can pick it up. So before all of these fancy imaging studies and newborn screening algorithms, doctors really just had to rely on the physical exam. So here are the things that you should look out for. Basically the presence of central cyanosis and this is um people often talk about cyanotic babies, but these are some pictures of what cyanosis actually looks like. Uh so importantly around the mouth, um in the uh the tongue and so those are good places to assess for cyanosis. Now as you can start to tell, there are so many different types of congenital heart diseases. So to break them up, Dr. Pater divides them into aanotic and cyanotic. So let's start with the aanotic heart diseases. How do these typically present? Uh so typically the way uh these patients will present uh is withnia, uh slow feeding and sweating. Um and they often will have signs with hepatomegaly. Um sometimes they have a flow murmur and often times they have a failure to thrive. Um on the chest x-ray they'll have um increased pulmonary vascular markings and the heart will look big. Most of the time the blood is going from the left ventricle, red blood is going from the left venal uh through the VSD to the right ventricle and back to the lungs and that's how they get over circulated and how they have um white out on their chest x-rays. But if they are screaming their brains out, then it's possible for blood to go from the right ventricle across the VSD and out the left ventricle into the body. And so they can be transiently blue, but that's not necessarily um concerning cyanosis. Okay, let's jump into the different types of heart disease. We'll start with the patent ductus arteriosis, otherwise known as the PDA. So it's the little connection between the pulmonary artery and the aorta and so it's um used in utero for that blue blood to bypass the left side of the heart. Um and it's supposed to close postnatally. If it doesn't close, then it can lead to red blood going from the aorta to the pulmonary artery because the resistance in the lungs is lower than the resistance in the aorta and so all the blood is going downstream into the lungs. Um and so we will close those um if the child is over circulated and symptomatic over circulated. So kids in the NICU who can't come off of the ventilator, they can't grow, they can't breathe on their own. Um and they think that the PDA is contributing to their inability to progress. Um or long term if there's a risk of pulmonary hypertension and there's a theoretical risk of endocarditis. So how is a PDA repaired? Nowadays most of these are on our end are closed in the cath lab with um device occluders um like we've seen here on the lower left. For a child who's too small for one of the typical devices, um they can be surgically closed and that's usually done via a lateral thoratomy with ligation and then division. Okay, so now let's talk about ventricular septal defects or VSDs. There's actually a few different types to keep in mind. Uh by far and away most of them, the most common ones are in the um muscular um septum and those tend to uh close over time. The ones that often don't close are the ones that are in the peri membranous region, which is um kind of below the aortic valve and the uh fancy doubly committed subarterial or super crystal or jux arterial, whatever you want to call them that sit right under the aortic valve. Some of these VSCs will kind of close as the child grows and the ones that don't um will need surgical repair and the way that they're closed is um simply by patch closure. All right, we got another awesome animation from the Media Lab at Cincinnati Children's, showing surgical patch closure of a VSD. So first, the child is placed on bypass, as you can see here. Then an incision is made in the right atrium. We can follow that view down into the atrium and then into the right ventricle. And then you can see the large defect that they have to correct. So the patch is brought in. And sewn into the septum. Once that's in place, then the atrial incision is closed and normal circulation is resumed. All right, moving on. Let's talk about atrial septal defects or ASDs. Again, they come in some different flavors. There's um secundum ASDs that are right in the middle of the atrial septum, primum defects that are um closer to the AV valves and then the sinus venosis defects that are uh by the IVC and the SVC. The only reason that it matters um essentially is that um there are a lot of catheter based um closure options. So we can close most secundum ASDs in the cath lab when the kids are around three to five years of age. Um but if for some reason there are insufficient rims. It kind of looks like a giant Oreo. So um if there are insufficient rims for the device to be able to sit onto, um or it's in a location that is not amenable to cath based closure, then they get surgical closure uh either with a patch or um by direct closure. Again, we have an awesome animation from the Media Lab at Cincinnati Children's. Here they're going to show you a patch closure of an ASD. So first again the child is placed on bypass. We have a right atrial incision and once they open that up, you can already see the large atrial defect, the communication between the right and left atria. So a patch is brought in, sewn into place and then the right atrial incision is closed and normal circulation again resumed. Okay, next we have a mouthful. Atrio ventricular septal defects or AVSDs. So what are those? Uh essentially there's kind of a spectrum of defects. So there's a complete AVSD, which is effectively one big atrio ventricular valve, uh all the way to partial defects, which is essentially um two AV valves, a left AV valve and a right AV valve and oftentimes um not a VSD uh associated with it and sometimes uh an ASD associated with it. All right, this one's kind of confusing, so let's just break it down. Let's start with some basic anatomy. Here are all the major structures labeled out and then right in the middle of the heart, you can see there's a common AV valve. So let's zoom in to this view. Here this is if we're looking at it from the left atrium and you can see the common AV valve here and then right next to it, you can see that's an ASD. Now let's change views. Here's as if we're sitting in the apex of the right ventricle. You can see the mitral and the tripid valves have kind of fused and formed this like one big common valve. And then there is a VSD. In the complete defect, it can also be unbalanced. So either unbalanced to the left or unbalanced to the right and um effectively what that means is that uh the defect only opens into one of the chambers and so the other chamber doesn't grow. So these children end up with a single ventricle. Now, let's say we have a complete balanced AVSD. Uh and so a lot of these kids end up going down a single ventricle pathway. Um in a complete balanced AVSD, they essentially act like a big uh VSD and so these kids will get uh surgical repair also around four to six months of age. If it's an incomplete defect, often times all they have is um the an ASD and they will get surgery around uh one to three years. All right, so there are two surgical procedures here, two different approaches. You have a single patch and a double patch repair. So for the single patch repair, you basically have an ASD patch and then that common AV valve, they kind of smoosh it and then place it over the crest of the ventricles. Now if you do a two patch repair, then you have basically just what it says. You have an ASD patch and you have a separate VSD patch. Okay, so last of the atic heart diseases, let's talk about cortation of the aorta. Um and then finally in the non cyanotic heart disease is cortation of the aorta. So many kids are walking around with cortations. Those that need intervention are those who have um heart failure, so basically ventricular dysfunction because the left ventricle is pumping against this kind of like narrow tightening. Uh if there's a gradient less greater than 20 by calf or if um the body is developing collateral circulation around it. Uh typically these are repaired when they're discovered. Um most of the time they're discovered um in infancy or um in you know, when kids are younger, but probably once every couple months or so, we have an um an older kid or an adult who is um getting evaluated for hypertension and someone realizes that they have no lower extremity pulses or that they have a gradient between the uppers and lowers and so then they need um get referred. Um the options for intervention are with a stent uh if they're big enough in the cath lab. Um and if not surgical intervention and the surgical options are with an end to end anastomosis or um historically with the subclavian flap graft. Um and this is um occasionally used and of worth noting to non cardiologist because the uh left subclavian is sacrificed in order to be able to um create the graft and um to open up the cortation and so these patients uh should not have blood pressures monitored in the left upper extremity because it'll be unreliable. So that wraps up the basics of congenital heart disease and then specifically the aanotic diagnoses. In part two, we're going to cover the cyanotic heart diseases. But until then, subscribe to our YouTube page, follow us on social media, download the Stay Current pediatric surgery app. And until next time, I'm Rod from Cincinnati Children's and remember, knowledge should be free.