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Congenital Heart Disease

The incidence of heart disease is 0.8 out of 100 infants or 8 per thousand infants are born each year with a heart defect. That number, when you look at it sounds kind of small but congenital heart anomalies still account for the highest percentage of all fetal heart anomalies. So fetuses born with any type of anomalies, congenital heart disease represents 25% of all of the fetal heart anomalies. 1 out of 100 kids are eventually evaluated by a pediatric cardiologist and in the United States there are 25-30,000 kids born each year with heart defects congenital heart disease, patent ductus arteriosus, atrial septal defect, hole in heart, ductis arteriosus, ductus arteriosis

The list of common heart defects. The incidence of them and really their order hasnít changed a whole lot over the last 100 years as weíve been studying them. In a more recent study where they analyzed over 5000 kids born with heart disease, still by far the most common heart lesion is ventricular septal defects. That occurs in 14%. Thatís followed by your secundum atrial septal defects. So our septal defects are still by far the most common of the heart lesions. Thatís followed by pulmonary valve stenosis, myocardial disorders, patent ductus arteriosus Ė this is not the preemie born with a PDA but these are the term ones who the ductus has not closed in. Then the two most common cyanotic heart lesions are tetralogy of Fallot Ė thatís in 6.3% and then transposition is in 6%. So the two most common are tetralogy of Fallot and transposition of the great arteries for the most common cyanotic heart lesions. Then from 8 to 12, the bottom is filled by our left-sided heart lesions: aortic valve stenosis, AV canal which weíll spend quite a bit of time on, mitral valve anomalies, coarctation of the aorta and the dreaded hypoplastic left heart syndrome.

Heart murmurs. The vast majority of heart murmurs in kids, as you all know, are innocent. We get the easy job because you have to do this big sorting of the large mass of kids to try to decide which are innocent and which are pathologic and then we only get to see a proportion of the ones that youíve already weeded out. But 75-80% of kids, during the first five years of life, will have a heart murmur. A vast majority of them are innocent murmurs. You can hear just vibratory murmurs. As blood passes through their valves, it vibrates the mitral valve apparatus. You hear that and thatís your classic vibratory Stillís murmur.

Lots of times if you have a very prominent murmur, as the kids get older and they donít go away, you can have a normal variant which is a false tendon in the left ventricle. You have a little tendon at the very bottom of the left ventricle that kind of acts like a guitar string. As blood goes in and out, it vibrates that string causing the normal murmur which is like a Stillís murmur. So youíd hear a lub-pink-dub, lub-pink-dub. So if you hear a murmur that really sounds like youíre plucking a guitar string, most of the time thatís normal. So a vast majority of murmurs in children are innocent especially after, like, the age of 1. If youíre hearing really prominent murmurs in the first year of life, especially the first six months of life, they tend to be more pathologic. But from 1 to 5 thatís when you have your highest incidence of innocent murmurs.

So before we call a murmur totally innocent we have to have absolutely no suspicious history that weíve gotten for organic heart disease. There are no other additional physical findings that are suspicious so they donít have hepatomegaly. Theyíve got normal pulses, everything. Plus that innocent murmur has to have the classic sound, the classic findings, for a particular innocent murmur. If you have the triad of these things, you really donít need an additional testing. If you have an experienced ear, normal EKG, weíre not going to do additional testings. Itís generally not needed to say that itís an innocent murmur.

Some of the pitfalls of our history and physical. Murmurs sometimes can appear later. As we talk about it, the murmurs sounds change by difference in both pressures and really difference in resistances between the chambers. If you have a large hole or a large VSD right when a child is born, well, if the pressure and the resistance is the same in the left ventricle and the right ventricle, thatís not going to create any noise.

So until, like, the resistance in the lungs drops and the pressure in the right ventricle drops, youíre not going to get a murmur from a large VSD. So they can appear late. You donít necessarily have them right away. Initially, you have elevation of the pulmonary vascular resistance. So as the lung resistance is up, youíre not going to hear murmurs that you will hear later once the pulmonary resistance drops.

All the symptoms that we talked about Ė poor feeding, tachypnea. None of these are specific. They can also signify anything else so there is no pathognomonic thing that you can look at on your history and physical that will say, "Think heart disease."

The clinical detection of cardiac enlargement is difficult. You obviously donít do chest x_rays on everybody unless you really have something to be suspicious about and itís hard to tell just on your physical exam. You can feel where your PMI is and see if itís in the midclavicular line but itís hard to just say, "Yes, theyíve got cardiomegaly" based on your physical exam. Respiratory rate as we talked about is frequently ignored and liver enlargement, although it most of the time goes with heart failure, itís not constant. Itís not 100%.

So now weíre going to spend the rest of the time talking about all the different types of heart disease and the different lesions. Weíre going to break the categories of heart disease into four types: The left to right shunts, right to left shunt, obstructive lesions and myocardial abnormalities. Iím going to talk about these three and my partner next is going to talk about the myocardial abnormalities.

The easiest way to think of heart disease, especially if you have a patient with real complex heart disease with lots of things Ė weíre going to be talking about general big categories but thereís obviously hundreds of different combinations Ė just try to, in your mind, break it down to overall are they getting too much blood flow to their lungs or are they overall getting too little blood flow to their lungs. If you break it down just into those two basic categories, it really helps to understand it.

If you end up having overall too much blood flow to the lungs, then that gives you symptoms of congestive heart failure. Congestive heart failure in kids really only means pulmonary over circulation. Itís not like congestive heart failure always in adults where you have pump failure as well. In kids, itís very rare to have pump failure so congestive heart failure really only means pulmonary over circulation. So if youíve got too much blood going to the lungs, whatís going to happen? Well, theyíre going to breathe faster because theyíre going to try to get rid of this extra fluid thatís in their lungs. So all their calories are going to be going towards breathing and not really growing so these are your failure to thrive kids and the kids that arenít growing well, are growing less on their percentiles, then obviously our surgery is going to be aimed at decreasing this overflow and rebalancing things.

Then what happens if they get too little blood flow to the lungs? If theyíve got too little blood flow to the lungs, then not enough blood is getting appropriately oxygenated so theyíre going to be blue. But theyíre not going to have extra flow to their lungs so their breathing is going to be pretty normal and their growth is generally not compromised. So usually the cyanotic kids are ones that donít ever have trouble with failure to thrive. They're usually big babies and obviously our surgery is going to be aimed at increasing the overall flow to the lungs.

So now going on to the specific left to right shunts, left to right shunt is defined as a condition in which oxygenated pulmonary venous blood or basically red blood goes back through the lungs rather than being delivered out to the systemic circulation or to the body. So weíve got extra red blood going to the lungs rather than being delivered out to the body. The four most common lesions on this are atrial septal defects (ASD), VSD, patent ductus arteriosus and AV canal defect or the newer name for that is atrioventricular septal defect but still most people call it AV canal.

Now, all these diagrams, in the top youíll have the normal heart and in the bottom the lesion that weíre going to be talking about. Obviously, everybody knows blue blood normally goes out to the lungs, picks up oxygen, comes back red and goes out to the body and usually thereís no mixing at the atrial or ventricular levels. In an ASD, youíve got a hole between the top chambers of the heart.

Now, everybody is born with a patent foramen ovale. This hole has to be open because that has to be present to deliver oxygenated blood from the mom to the fetus in utero. So everyone has to be born with a patent foramen ovale. But at the flap, that will close over as the pressure in the left atrium increases, that will push against the flap to close it over. 25% of the general population, the PFO doesnít totally close. So 25% of adults will have a small PFO and itís becoming harder and harder to decide as they get older which of these need closing and which donít but weíll go into that a little bit more

But if you have a true deficiency of how much tissue is in the atrial septum, then youíve got a true atrial septal defect and then what happens is blue blood goes out to the lungs and picks up red blood. But since the resistance is always lower in the right sided chamber, your RV pressure is only 30, your systemic is 90-100, itís easier for blood to come to the right side and get pumped out to the lungs. Itís almost always that you have a left to right shunt at the atrial level because the resistance is lower on the right side. So what you end up having is eventually you get right side volume overload and if you have a real large ASD, you can get an increased RV impulse.

On EKG, you may see right atrial enlargement. Thatís unlikely unless itís real severe. More commonly, youíll just see right ventricular hypertrophy. On x-ray, you can see increased heart size, especially the right sided structures Ė the right atrium and right ventricle and PVMs or pulmonary vascular markings. Increased pulmonary vascular markings.

On exam, youíd get a nonspecific murmur just from the extra blood going out to the lungs. So you hear a pulmonary ejection murmur. So a systolic ejection murmur at the left upper sternal border which is the pulmonary region. You may hear an extra sound that extends into diastole so the murmur may sound a little longer going into diastole and thatís what we call a tricuspid diastolic flow rumble. If you hear a murmur that goes into diastole Ė a diastolic flow rumble Ė what that signifies is youíve got probably twice as much blood going across the tricuspid valve as you do across the mitral valve. So thatís implying to us when we hear a tricuspid diastolic rumble that itís a pretty big hole because our shunt, or what we call our QP to QS, the flow to the lungs compared to the flow to the body is at least 2:1. So youíve got twice as much blood going to the lungs as youíve got going to the body. So when we hear that then that's a pretty good sized atrial septal defect.

The reason you have the fixed split S2, thatís always a test question in everything. When weíre in med school, on boards and on everything else, they always say, "What heart lesion has a fixed split S2?" The answer is always atrial septal defect

The next one is a ventricular septal defect and in VSDs, just like ASDs, the hole is in the bottom chamber so the red blood comes back, goes through the hole and more directly out into the lungs. Unlike the ASD where youíve got a big right atrium as a compliant chamber in here, here you get more shooting just directly into the lungs through a VSD. So you get more symptoms even with a less QP to QS ratio because you donít have all these big compliant chambers to hold that extra blood.

So VSD, the hemodynamics really depend on the location of the VSD. They can be anywhere along the ventricular septum, this thin region which is the perimembranous region, more in the muscular regions and then outlet/inlet portions. The ventricular septum is a 3-D septum and it doesnít really do it justice by showing it on 2-D like this but you can have the holes anywhere and the findings really depend on the location, the size of the lesion and what the pulmonary resistance is. The lower the pulmonary resistance, the more flow through the hole. The higher the resistance, even though you have a

Just to show you on the 3-D nature of the hole, the perimembranous area is one of the most common for where we have the holes but itís a very small area. Itís a thin area. If you shine a penlight to it, this is the only area of the septum that doesnít have any muscle. You can see it through from the left ventricular side in here and thatís just right close to the tricuspid valve. The rest of this region is the muscular septum. Right under the tricuspid valve, a hole anywhere in here is called an inlet VSD or thatís the AV canal type VSDs. Up here, more under the pulmonary valve, thatís called our outlet or super crystal ventricular septal defects. Just so if you hear those terms, those are the locations in

So those are some of the complications and thatís mostly just by the jet effect or the Venturi effect in there. So you can get RV outflow tract obstruction, you can get a subaortic membrane aortic insufficiency. You can get SBE or sub acute bacterial endocarditis. Bugs love to sit in turbulent areas and itís a very turbulent area. You can also get pulmonary hypertension or Eisenmengerís disease and you can obviously die early if you have a big hole thatís left untreated.

The next lesion, patent ductus arteriosus. The ductus arteriosus is a tube that connects the aorta and the pulmonary artery. You need to have that in utero because in utero the babies arenít breathing. So the lungs are collapsed and the blood is diverted from the lungs directly to the fetusí body. But that usually closes off within the first week after life. If it stays open, then itís called patent Ė because it stayed open Ė ductus arteriosus. Then what ends up happening is the red blood, since the resistance is lower into the lungs, goes in from the aorta through this tube back out directly into the

The symptoms depend on how big of a scoop we took. So the extent of the lesion. How big the ASD is, how big the VSD is and more importantly, how that one common AV valve is functioning. These kids usually have bad failure to thrive because they have a lot of pulmonary overcirculation. On EKG, they get left access deviation because the mid portion or their AV node part isnít at the right place either.

Weíre mucked up with the entire middle of the heart so on EKG, even though you may not hear any murmur because they have huge holes and they may not have valve leaking, if an EKG is abnormal on a baby with Down syndrome and theyíve got left access deviation, they almost always have heart disease regardless of whether you hear anything or not. They can have left ventricular hypertrophy, biventricular hypertrophy Ė they have huge hearts on x-ray. We do a lot on babies with Down syndrome, obviously, almost every one thatís born and the doctor or the pediatrician or family practitioner will always be surprised when I call back and say, "This baby has AV canal" or "They have this bad lesion." And they go, "But I donít hear any murmur." It doesnít matter if you donít hear any murmur, but you put your hand on that babyís chest and itís like ba-boom! ba-boom! under it. I mean, just by putting your hand on their chest, you know whether they have a hear lesion or not. They really have very impressive RV and LV impulses. Sometimes they can have an increased P2 component from pulmonary hypertension and usually if you hear a murmur, itís not from their holes. Itís because their valve is leaky and youíre hearing the AV valve regurgitant murmur. They usually have huge livers as well. Theyíre also hypotonic so it makes their liver seem lower.

But they have usually terrible congestive heart failure because theyíve got torrential PBF, this pulmonary blood flow, and also from AV valve regurgitation. They develop pulmonary hypertension very early. We donít understand what it is about Down syndrome and their lung arteries but they are abnormal. Whereas other kids with ASDs, VSDs donít develop pulmonary hypertension until maybe theyíre in their teens or 20s or 30s. Some of these can develop pulmonary hypertension as early as six months and then theyíre irreversible after that point. Thatís why we donít wait on a baby with Down syndrome to diagnose them. Now we treat them all early. We close them by the time theyíre three to six months old because we donít want to have irreversible pulmonary hypertension. They can develop endocarditis and they obviously will all die early if we donít treat it.

So that takes care of all the left to right shunts. On the right to left shunts, thereís lots of them but weíre only going to talk about the two that are the most common. A right to left shunt is defined as a condition in which desaturated systemic blood or basically blue blood goes right straight out to the body without going through the lungs. So thatís the definition of a right to left shunt and thereís lots. I only listed the top eight. This list can go on and on with different variations but the two most common are tetralogy of Fallot and transposition of the great arteries and those are the two that weíre going to discuss.

The biggest challenge to you guys is when you have a blue baby thatís in the nursery is you have to decide is it lungs or is it the heart. Thatís your two main differentials. One of the tests that you can use is an oxygen challenge test. You get what their ABG or their gas is in room air and then you repeat that after putting them on 100% oxygen for about 15 or 20

What is tetralogy of Fallot? Dr. Fallot described this lesion in the 1800s, sometime I think in the 1870s and he thought it was four separate lesions. Thatís why they called it tetralogy. The four lesions are you have this big ventricular septal defect, you have overriding aorta, you have pulmonary stenosis and you have right ventricular hypertrophy. So for the longest time, we thought in development there were a lot of things that went wrong to give us this problem and then we found out really it isnít many different things that cause this problem, itís one thing.

Everybody starts having a hole in utero and what ends up happening is that the bottom part of the ventricular septum comes up and meets with the top part of the ventricular septum and it closes off the hole in utero. Well, in tetralogy of Fallot, what happens is the top part of the ventricular septum comes in crooked. So the bottom part is coming up like it should but the top partís coming in crooked and so they canít even meet so you end up having a hole. Depending on how crooked it is, it takes the aorta with it so it makes it overriding and then it scrunches in the RV outflow tract and youíve got the pulmonary stenosis. Thatís what differentiates a "blue tet" versus a "pink tet". In a pink tet you donít have very much whereas a blue tet itís scrunched all the way over and you can even have like pulmonary atresia. So the ones that present later at three to six months are ones that are basically more VSD. They donít have much PS but the ones that present earlier and are bluer, they have more degree of pulmonary stenosis.

So what it really results from is an anterior displacement of the infundibular septum which is a fancy way of saying that that top part of the septum comes in crooked or comes in more anteriorly. Cyanosis can appear late if itís not very crooked.

The next lesion is transposition of the great arteries and in transposition of the great arteries, as its name implies, the great arteries are switched so the blue blood goes straight out to the aorta and the red blood keeps going out to the lungs. The only reason that you have any mixing is because in utero everyone has that hole between the top chambers, the PFO, so some blue blood can go out to the body when babies are immediately born because of this hole. You also have the ductus here so some blue blood can go into the lungs to pick up oxygen.

You get into trouble when this ductus closes because now you have no blood picking up oxygen at all. So these are babies that are born with severe cyanosis within the first few days. These are always big large babies. The nurse calls you, they say theyíve got a four kilogram male whoís sitting there at 60-70% saturation whoís breathing totally comfortably,

Obstructive lesions. Pulmonary stenosis, aortic stenosis, coarctation of the aorta and the very severe end of that which is interrupted aortic arch and then the dreaded hypoplastic left heart syndrome.

Pulmonary stenosis. Your pulmonary valve is made abnormal and kind of sticks. It doesnít open all the way so it domes. So instead of opening all the way like a valve should itís just opening partially so what ends up happening is blue blood goes out to the lung. But your right ventricle has to generate higher pressure to deliver that same amount of blood through a smaller orifice. So we determine the level of how severe the pulmonary stenosis is by how much pressure that the right ventricle has to generate in order to pump it out.

Normally, your pressure in your right ventricle is only one-third of what it is systemically. So if itís 90 here, itís only 30 here. If itís from one-third to one-half systemic, we call it just mild pulmonary stenosis. If itís like one-half to three-quarters systemic, then itís more moderate and if itís greater than three-fourths systemic pressure in here then itís severe pulmonary valve stenosis.

So on exam, again, these kids are asymptomatic. EKG, all you see is right ventricular hypertrophy. X-ray you may see a

So what do we do? Well, if itís mild, we do nothing. We just follow it along and if it gets to the moderate and closer to the severe category, then we usually go in and do a balloon valvuloplasty. We put a special catheter with a balloon across the pulmonary valve, open the valve up so it kind of opens the valve better. Most of the time, you only need to do this once in a lifetime and it generally takes care of it. Very rarely they have thick, really ugly, gnarly looking valves that donít open and the surgeon has to go in and do a valvotomy. Thatís usually in kids that have other lesions, you know, Noonanís syndrome or something else and the valve is just not made right.

This is what you see in the balloon procedure. This is a balloon valvuloplasty. This is the right ventricle. This is the thickened pulmonary valve and you see a very tiny jet of contrast that goes across that valve into the lungs. You put in a balloon across that valve, open that valve up and then afterwards you see how more blood is now going through that valve out into the lung arteries. Then you balloon it until the pressure is down to where you 

Coarctation of the aorta. Now weíre just going down further on where itís narrowed. So now right as the subclavian goes off, the left subclavian you get a narrowing on the aorta and usually when theyíre born, your ductus goes below this narrowing. So your ductal flow, as long as the duct is opening, theyíre still getting blood supply to their legs and to their kidneys. But as the duct closes off, then they may not get hardly any blood supply to their kidneys or their legs. So thereís two types of coarcts depending on how they present. So if itís really tight, theyíll present as shock in the newborn period as that ductus closes. Or if itís not that tight of a narrowing in the newborn period and they get beyond the newborn period, then theyíll come in later with either decreased pulses in their legs or with hypertension in their arms.

How do we treat them? If they present very sick in the newborn period well we know itís because the ductus closed. So again we take out our holy grail medicine, prostaglandin E1, and reopen that duct until we can fix it. Then the surgeon goes in and most of the time he just does an end to end anastomosis where he cuts the bad part out and then rejoins the good part of the aorta. Sometimes after they get older, after a year of age, we can consider doing a balloon aortoplasty but youíre going in with a balloon catheter and youíre stretching it. The wordís still out on just ballooning because if you get intimal tears and dissections in the aorta, thatís bad. Thatís worse than sending a surgeon in there to do it but now weíre doing some of them in the kids and putting stents in so you donít get the dissection and youíve got that but, again, we donít have 10-20 year followup on these aortic stents.

The last lesion Iím going to discuss is the dreaded hypoplastic left heart syndrome. Like its name implies, the left heart doesnít form. Thereís at least a thousand of these babies born in the United States per year and we seem to have a disproportionate amount. But you get blue blood coming back to the right side of your heart, it goes out to your lungs and picks up oxygen. But now youíve got mitral atresia so it canít go into the left ventricle. Thereís no left ventricle for it to go into so the red blood has to come through this PFO out toward the lungs again. So the only way your body is getting any blood is both blue and red blood mixing, going through the ductus and then out to the body. So all the blood going to your brain is retrograde, going backwards, because nothing is going forward and all the blood going to your coronaries is retrograde as well.

Then the last stage is called the Fontan procedure where we totally bypass the heart altogether. So you take the IVC blood, you put in a tube and connect it to the SVC. So now all the blue blood goes directly to the lungs without a pump. So basically itís just getting sucked into the lungs because your lungs have lower resistance and then the red blood comes back to the heart and out to the body.

Well, what are the long term problems of this going to be? Well, now weíve got a big right ventricle pumping out to the body. So in 20 years weíre in trouble within all these kids. Also anything that increases their pulmonary resistance, they get bad pneumonias or anything, now theyíre not getting blood out to their lungs. So itís not the worldís greatest procedure but it gets them to live and itís three open hearts. We do that for all single ventricles which is called the Fontan operation. So if you see that, this is