Okay, we got an absolutely important question here.
It's challenging. Let's jump right in.
A 2-year-old boy is brought to the pediatrician due to poor weight gain and easy fatigability.
His mother states that the patient barely engages in any physical activity, as he becomes short of breath easily.
Prenatal and birth histories are insignificant.
Past medical history includes a few episodes of upper respiratory tract infections that were treated successfully.
The patient is in the 10th percentile for weight and 40th percentile for height.
His heart rate is 122 beats per minute and respirations are 32 per minute.
Cardiac auscultation reveals clear lung sounds and a grade II/VI holosystolic murmur heard loudest at the left lower sternal border.
The rest of the physical examination is negative for clubbing, cyanosis, and peripheral edema.
Which of the following is the most likely diagnosis in this patient?
Answer choice A: Patent ductus arteriosis (PDA);
Answer choice B: Atrial septal defect (ASD);
Answer choice C: Ventricular septal defect (VSD);
Answer choice D: Coarctation of the aorta; and
Answer choice E: Tetralogy of Fallot
Now take a moment to come to your own answer before we go through it together.
Okay, this is a super important question.
The question stem has a lot of information.
There are some complex physical exam findings and this is bread and butter for step two so let's really focus in.
Now, looking at the question characteristics, we can tell it's a cardiac question within internal medicine.
You have a child who's got this holosystolic murmur.
There seems to be some tachycardia and tachypnea so your brain should already be going to heart.
Now, this is actually a one-step question.
All they want from you is just the diagnosis but man, that's not an easy question.
There is a lot of information so though it's a one-step question, it's still really challenging
because you have to take a lot of information and bring it together.
And of course, the stem is absolutely required.
We gotta take all those information pieces and bring them together and dissect them out of the stem.
So, let's do that now.
Now, let's look at the question stem and take out the vital information and actually ignore the filler information
so we can isolate the pieces of information that we need to be able to come to the correct diagnosis.
Now, the very first thing we see is that we have a pediatric patient.
A two-year-old boy. Now, that's really important.
Cardiac conditions in kids versus adults is very different
so already your brain can kind of shift into thinking aboutpediatric cardiology.
Now, the chief complaint here really is failure to thrive. Even though that phrase is never mentioned in the stem,
not that you kind of have to figure out in your head as part of the thinking process.
Now, that's kind of actually shown in the question stem.
The mother notes that the child has poor weight gain
and we actually have objective data that he's in the 10th percentile for weight, that's really low.
Now, in addition to him having failure to thrive, what they're also describing in the question stem or what are called hypoxic events.
In which you see hypoxia inadequate oxygen delivery, patients will have fatigability.
Like this kid does.
You know he doesn't really -- it says, engage much in physical activity
cuz he gets tired fast and he also has shortness of breath.
Now these are kind of little clues to get your brain thinking about hypoxic events
but what is very important is that the hypoxic events are acute, they are not chronic
and you can figure that out by looking in the question stem when they give you physical exam negatives,
and that there is no clubbing of the fingers, no cyanosis or peripheral edema
as those are clinical exam findings of chronic hypoxic injury, not acute.
Now, there are some cardiovascular signs that we had noted, tachycardia, tachypnea
and the elephant in the room, the holosystolic murmur.
Now, taking into account all of these pieces of information:
he's a kid, he's got symptoms and chief complaint of failure to thrive, he has hypoxic events,
he's got cardiac abnormality on exam.
You should really be thinking about some type of cyanotic congenital heart disease or defect.
Now, bring that together in your head, failure to thrive, hypoxic events, abnormal heart.
You need to be thinking like me in this case and say, "Ah, cyanotic congenital heart disease.
Now, let me figure out which one it is."
This is where it gets really high-yield.
This patient has a grade II/VI, holosystolic murmur best heard in the left lower sternal border,
that is a heavy pieces of information that is going to help you.
Now, in this case, it's heard at the left lower sternal border
and it's holosystolic, meaning you hear it at the entire time during just asystole.
Now, this is actually pathognomonic for a ventricular septal defect and that's actually the right answer here:
answer choice C, a ventricular septal defect. Now, let's look at VSD's
and figure out why it makes sense then we'll go through the other answer choices and explain how they're wrong.
Now, with respect to test-taking strategy, in this case,
I will also show you in a few moments how you can eliminate answer choices as them being wrong.
But in this case, what I really want you to do is not really rely on test-taking strategy.
I want you to be able to figure out, know the pathognomonic heart sounds
and then just get the answer, click the right answer and move on to the next question.
Save time on the exam on these kinds of questions that you can dominate if you know the core information.
Now, let's refer to an image that actually has an image of a large ventricular septal defect
on the left and Eisenmenger's syndrome on the right.
Now, ventricular septal defect is the most common congenital heart disease.
Okay, if it's most common, you better remember it, right? So it's the most common congenital heart disease
and its presentation actually varies depending on the size of the ventricular defect.
If it is a smaller defect, these are typically asymptomatic
but interestingly, you'll have a louder murmur because there's turbulent flow across a smaller defect.
But on the other hand, if you have a larger ventricular septal defect, these tend to be quieter on exam
but they actually will have a more significant left to right shunting of blood and then the kid will have more symptoms.
Now, given the clinical kind of story we have here in the stem,
we can see that this kid likely has a large ventricular septal defect.
Now, how can you diagnose that?
Well, cardiac auscultation is step one looking at symptoms is kind of their step two
but really what you need to do is to do a transthoracic echocardiogram
to actually be able to determine the ventricular septal defect and then there are two ways where you can see it.
One, you can put flow on and see the flow going between the shunt or you can do a bubble study
to also show the bubbles going across which shows the ventricular septal defect.
Now, large ventricular septal defects like this kid on our question has actually led to a significant left to right shunt
that can result in pulmonary over-circulation, pulmonary hypertension, growth failure, and congestive heart failure.
Which is what this kid's starting to get since he's got some respiratory distress
and easy fatigability, these are signs of congestive heart failure.
Now, if you have a ventricular septal defect, you will have shunting of blood from the left to the right side
and that's because the left ventricle is stronger, the muscle is bigger,
and it's going to be pumping blood out of the aorta.
The left ventricle has higher pressure than the right.
So, if you have a ventricular septal defect, look at the image here, the blood's gonna go from the left ventricle to the right.
Now, in a chronic state when you have persistent left to right shunting
because you didn't repair this ventricular septal defect, you're going to develop chronic pulmonary hypertension
and then you'll actually have reversal of the blood flow, in which it'll go from right to left
because all that pressure over time caused the right ventricle to become stronger
and have a bigger muscle and hypertrophy, and then the actual flow will reverse.
Once this happens, it is named Eisenmenger's syndrome.
Absolutely high-yield, you know that. That's basic. Memorize it.
And then when patients have Eisenmenger's syndrome, they develop cyanosis, clubbing, and dyspnea.
Now, what's interesting also very high-yield. Memorize this. Patients that have a large ventricular septal defect
are actually at an increased risk of infectious carditis.
That could be another question on the exam, very likely, very high-yield. Memorize it.
Now, when do you treat a ventricular septal defect? And the answer is not always.
Now, it really depends on the size and the severity of symptoms.
Small defects actually usually close spontaneously and don't require treatments
so you don't always gotta go in there mucking around.
Large defects though generally do require a combo treatment therapy.
In which you need to get medication such as like diuretics to treat the heart failure
and you usually need to do some kind of closure of the ventricular septal defect.
Usually surgical or transcatheter because you want to do that
before the kid develops Eisenmenger's syndrome.
Now, let's go back to the question answers to see how we could have eliminated other ones
if you did not know the pathognomonic cardiac auscultation sign for ventricular septal defect.
Now, look at option A, a patent ductus arteriosus.
Now, this is most commonly seen in patients who are born premature
and they will have a cyanotic congenital heart disease.
Well, this kid wasn't born premature but more importantly,
the heart sound that you will need to know for patent ductus arteriosus
is a continuous murmur heard best in the left infraclavicular area.
And that would be very pathognomonic for a patent ductus arteriosis.
A continuous murmur.
Some people even say a continuous machine-like murmur
heard best in the left infraclavicular area, that means below the clavicle.
Now, look at option B. So you could've eliminated A because well, that's not the heart sound that we're hearing.
We have a holosystolic, not a continuous murmur and it's also in the wrong part of the chest.
Look at answer choice B, atrial septal defect.
Now, patients that come in with an atrial septal defect, their cardiac auscultation
will have a wide splitting of the second heart sound or as we'd like to say, a splitting of S2
and that does not vary with respiration and that's heard in the left upper sternal border.
Now, a large atrial septal defect can eventually result in pulmonary hypertension and Eisenmenger's syndrome
but again, that's not the correct auscultation, a splitting S2 is not described so we can eliminate this as well.
Now, look at answer choice D, coarctation of the aorta.
Now that's very classically seen with Turner syndrome
and it can result in hypertension of the upper extremities and hypotension of the lower extremities
and the very important thing to know is that physical exam can reveal brachial femoral delay.
There is no cardiac auscultation pathognomonic sign,
it's more the brachio-femoral delay that you have to memorize
so you could've deleted this one again cuz this kid doesn't sound like they have turner's
and there is an auscultation pathognomonic finding which we would not see in coarctation of the aorta.
The last one, answer choice E, which is tetralogy of Fallot.
Now this is the most common cyanotic congenital heart disease
and it's characterized, and you gotta memorize this, right ventricular outflow obstruction,
right ventricular hypertrophy, overriding aorta, and a ventricular septal defect.
Now, the murmur of the tetralogy of Fallot is typically a crescendo, decrescendo harsh systolic murmur
best heard over the left upper sternal border.
Now, though there is a ventricular septal defect here, we don't hear the other signs that are being described for tetralogy of Fallot
which is the crescendo harsh systolic murmur. Instead, we have a whole systolic murmur.
So based on just knowing the very high-yield cardiac auscultation sounds for the different defects of the heart,
you could've quickly eliminated patent ductus arteriosus, atrial septal defect, coarctation, tetralogy of Fallot,
and landed straight into ventricular septal defect.
Also, don't feel like, "oh my god, if I don't know them all, what am I gonna do on test day?"
If you know some, at least you can eliminate some
and be left with something that's much more narrow.
So try to learn all the cardiac heart sounds the best that you can.
Now, let's discuss some high-yield facts regarding some other topics that are relevant to this question.
Now, first thing, failure to thrive. By definition, failure to thrive means insufficient weight gain in a child
and that can be due to insufficient calorie intake, malabsorption, and increased metabolic demand.
Now, it's most common in children with congenital heart disease.
It can be due to a multitude of the various mechanisms we just mentioned
but most strongly, it's actually due to insufficient calorie intake because they can't feed
and they get fatigued during feeding so they don't get enough calories.
Often parents will say the child will turn blue, they look out of breath,
so they don't actually feed that much at the breast so they get malnutrition.
Now the treatment here is treat the underlying condition -- you'll fix the failure to thrive.
Now, again, ventricular septal defect, what e talked about here extensively so far.
That's the most common congenital heart defect. [inaudible 15:10] is about two to six out of a thousand births.
You have incomplete fusion of the ventricular septum.
You'll have a left to right shunt.
Usually, these are asymptomatic at the birth so the kid comes out normal, no one's worried
and then they actually -- you start to have some symptom development in infancy
and the pathognomonic sound, you have to know, is a holosystolic murmur
and most commonly heard best at the left lower sternal border.
And really the treatment here like we discussed depends on the size of the defect.
If it's small and asymptomatic, it'll usually close on its own.
If it's larger, you may have to get medications or you'll probably will, and you'll probably throw on surgery as well.
Now, the other really high-yield topic here is Eisenmenger's syndrome.
This is when you have a left to right shunt and over time, you'll actually have a reversal of the shunt to have a right to left shunt.
Cyanosis is the main element because the low oxygen blood in the right ventricle is coming over to the left
and going out the aorta so you're actually making cyanosis a physiological reality.
Typically, that's associated with the septal defect of course and there is an increased risk of pulmonary hypertension.
Now, the incidence is actually decreasing due to more screening that is occurring and this is actually irreversible, unfortunately.
Once the right ventricle gets hypertrophy, there isn't really much for us to do.
A heart-lung or lung only transplant really is the only treatment option.