Welcome to the bed. We'll go ahead and give you
the story. This is all going to happen super
fast. Welcome to the emergency room. Imagine,
for a second, a heart the size of a strawberry.
It's beating 150 times a minute. It's essentially
sprinting a marathon. But the baby is lying completely
still in a plastic warmer. Yeah. And then you
introduce a structural flaw. The plumbing is
just, it's wired wrong. Exactly. The pipes are
crossed, or maybe a wall is missing, or a valve
is basically welded shut. It's a mechanical nightmare.
And for the parents, it is, I mean, it's absolutely
terrifying. Right. And now, put yourself in the
shoes of the nurse standing at that bedside.
You have to infuse a medication into that tiny
system. Yeah. If you get the math wrong or if
you push it too fast or miss a subtle cue on
the monitor. You can stop that heart. Or stop
that baby from breathing. That is the reality
of the pediatric cardiac ICU. It's high stakes,
high stress, and incredibly precise. The margin
for error is, well, it's effectively zero. Which
is exactly why we're doing this deep dive. We
aren't just reading drug labels today. We've
taken this massive stack of textbooks, clinical
guidelines, and drug monographs resources that
would honestly take weeks to digest. And we're
filtering them. We're looking for the Pareto
principle. The 80 -20 rule. Exactly. We want
the 20 % of the pharmacological knowledge that
is going to drive 80 % of your clinical decisions
and, you know, answer 80 % of those really difficult
board exam questions. So if you're prepping for
the NC... or if you're just trying to survive
your first shift with a blue baby, this is what
you need. This is your roadmap. And we should
be really clear about the scope here. We're going
to touch on defects, tetralogy of phallate, transposition
of the great arteries, but only as context. We
aren't teaching pathophysiology today. No, we're
teaching the chemical tools you use to manage
it, to fix it. We have four main stops on this
roadmap. First, we've got ductal dynamics. These
are the drugs that manipulate the fetal bypass.
The on -off switch. Then the failure fixers,
how we manage volume and squeeze. After that,
rhythm and flow, controlling the speed and the
thickness of the blood. And finally, the acquired
trio, the diseases kids can catch that actually
attack the heart. It's a heavy list, but we are
going to break it down so it sticks. Let's just
get right into it. Section one. Ductal dynamics.
This is the battle between open and closed. Right.
And looking at the literature, everything here,
it just revolves around one single structure,
the ductus arteriosus. OK. So set the scene for
us. Biologically, what are we actually looking
at? You have to remember that a fetus doesn't
use its lungs. In the womb, the lungs are fluid
filled and they're under high pressure. They
are, for all intents and purposes, closed for
business. But the heart is still pumping. The
heart is still pumping blood. So nature created
this incredible bypass road, a physical vessel
called the ductus arteriosus. And it connects
the pulmonary artery directly to the aorta. So
blood leaves the right side of the heart. It
heads toward the lungs, hits a road closed sign,
and just takes the ductus off ramp straight to
the body. Precisely. It skips the lungs entirely
because the placenta is doing all the breathing
for the baby. Okay, so what happens at birth?
Well, normally when a baby is born and takes
that first breath two things happen The lungs
expand which drops the pressure and the oxygen
levels in the blood just shoot up That surge
of oxygen trigger the chemical reaction that
clamps that vessel shot. That's just Usually
within a few days, it's totally closed. It becomes
a ligament. It's not a factor anymore. But here's
the crux of the problem for congenital heart
defects. In some of these babies, that closure
is catastrophic. Great. If you have a defect
like pulmonary atresia, where the normal road
to the lungs is completely blocked, or maybe
hypoplastic left heart syndrome, where the road
to the body is blocked, the ductus is the only
thing keeping the baby alive. It's the only bridge.
It is the only bridge allowing blood to get where
it needs to go. If nature takes its course and
closes that duct, the baby dies. It's that simple.
So we need a chemical doorstop. We need something
to physically jam that pathway open until the
surgeons can get in there and operate. And that
brings us to drug number one, alprostadil. Also
known as prostaglandin E1 or PGE1. Yeah. If you
work in an NACU or a CVICU, this is arguably
the single most critical drug in your crash cart.
It is a lifesaver. Let's start with the basics.
Drug description. I'm looking at the monograph
here, and it just says it's a potent, smooth
muscle relaxant. And that's the key phrase. The
ductus is a muscular vessel. Alprostidyl tells
that muscle to relax. Just chill out. By relaxing,
it prevents it from constricting. It maintains
ductal patency. That's the term you'll hear in
report. We're running prostin to maintain patency.
OK, so let's dig into the mechanism of action.
It's relaxing the smooth muscle. How? It binds
to prostaglandin receptors on the muscle cells
of the ductus. This activates a cascade inside
the cell that basically prevents calcium from
entering. Without that influx of calcium, the
muscle just can't contract. It's forced to stay
dilated. So practically speaking, if I'm in report
and I hear the phrase ductal -dependent lesion,
my brain should immediately jump to elprostidil.
Instantly. It's a direct one -to -one link. If
the baby's life depends on the ductus being open,
this is the drug they will be on. Let's talk
about specific defects. The outline links this
to transposition of the great arteries, or TGA.
Right. In TGA, the plumbing is completely swapped.
The blue blood from the body goes to the right
heart and back to the body. The red blood from
the lungs goes to the left heart and back to
the lungs. They never mix. They never mix. It's
two separate circles. That baby will die from
hypoxia within minutes unless you have somewhere
for the blood to mix. The open ductus allows
that. It lets some of that red oxygenated blood
cross over into the aorta and get to the body.
So it's a bridge. What about something like tricuspid
atresia or pulmonary atresia? In those cases,
the valve leading to the lungs is either missing
or sealed shut. No blood can get from the right
side of the heart to the lungs the normal way.
The ductus is the only source of pulmonary blood
flow. So blood goes from the aorta, backward,
through the ductus, and into the pulmonary artery.
Exactly. It's a reverse flow, but it's the only
way to get blood oxygenated. Okay. And on the
other side of things, hypoplastic left heart
syndrome, HLHS. In HLHS, the entire left side
of the heart is underdeveloped. It can't pump
blood to the body. So again, the ductus is the
only source of systemic blood flow. The right
ventricle pumps blood to the pulmonary artery,
and then it crosses the ductus to get to the
aorta and feed the body. So in all these cases,
if that duct closes, it's game over. Game over.
Now, when we start this infusion, what are we
actually watching for? How do we know it's working?
This is the core need to know stuff. The therapeutic
effect depends entirely on the defect. It's all
about what you're trying to achieve. So if the
baby is blue cyanotic, because blood can't get
to the lungs, like in pulmonary atresia. You
watch the O2 sats. Yeah. You start the drug.
and you should see the baby literally turn pink
in front of your eyes. The saturations climb
from, say, the 50s or 60s up into the 80s. And
if it's an obstructive lesion, like a severe
coarctation of the aorta where the aorta is pinched?
Then you're watching for perfusion. Before the
drug... The baby might have cold legs, pale skin,
and you can't feel the femoral pulses. The blood
pressure in the legs will be way lower than the
arms. Right. You start the L -prostil, the duct
opens, and it provides blood flow to the body
after the pinch point. Suddenly, you can feel
pulses again. The lactate levels, which were
high from poor perfusion, start to drop. The
baby looks, for lack of a better word, alive
again. That sounds like a miracle drug, but looking
at the side effect profile here, this is rough.
There is a boxed warning that seems to be a favorite
for exam writers. Apnea. It stops them from breathing.
It's a very, very real risk. Alprostidyl has
a central effect on the respiratory drive and
the brain stem. The data says about 10 % to 12
% of neonates will have an apneic spell. One
in 10. Yeah, and it usually happens quickly,
typically within the first hour of starting the
infusion. This feels like a massive trap for
a new nurse. I can see the exam question now.
You start alprostidyl on a newborn with TGA.
Fifteen minutes later, the baby stops breathing.
What is your priority action? And the distractors
will be things like stop the infusion or administer
epinephrine or call the provider. All sound plausible.
But you do not stop the infusion. Never. That's
the trap. If you stop the infusion, the duct
closes and the underlying heart defect kills
the baby. Apnea is a known, expected side effect,
not an allergy. So you treat the side effect.
You treat the side effect, you get your bag valve
mask, you support their breathing, and you call
for help to get them intubated. You ventilate
them. But you keep that prostaglandin running
at all costs. So the number one nursing implication,
the absolute safety priority, is never start
this drug without an airway cart at the bedside.
Correct. Intubation equipment, suction, a ventilator,
immediately available. In fact, if we're transporting
a baby on alprostitl, say, in a helicopter or
ambulance, We almost always intubate them electively
beforehand. Proactively. Exactly. You do not
want to be trying to intubate a tiny unstable
neonate in the back of a moving ambulance because
the drug kicked in and they stopped breathing.
It's all about anticipation. That makes perfect
sense. I also see fever and flushing listed here
as a common side effect. Is that an infection
risk? Usually not. It's a systemic vasodilator.
It opens blood vessels everywhere, not just the
ductus. So the baby turns red, gets hot to the
touch. It can look really alarming like a sepsis
flare, but it's usually just the drug working.
So you treat the temperature, maybe unswaddle
them, but you don't panic and start a sepsis
workup immediately. You don't panic. You also
need to watch for cardiovascular collapse. So
hypotension and brachycardia. if the baby is
particularly sensitive or if the drug is pushed
too fast. But apnea is the big one, the one you
have to be ready for. What about administration?
Can I run this through a peripheral IV in the
hand? You can, but it's risky. It's tough on
the veins and you can lose access. Ideally, you
want a secure central line or a UAC and umbilical
artery catheter. And here's a rigid rule. This
is a continuous infusion only. Meaning no interruptions.
Zero interruptions. You never flush the line,
you never bolus it, and you absolutely never
let the bag run dry. Because the half -life is
incredibly short. Seconds to minutes. If that
pump beeps infusion complete and you ignore it
for five minutes while you go get another bag,
the duct can start to spasm shut. Wow. And once
it clamps down, it is very, very hard to pry
it open again. The standard of care is to have
the next bag mixed and ready and you run two
pumps to switch it over so there is literally
zero interruption in the flow. That's a huge
nursing responsibility. It is. It's a life -sustaining
infusion. Okay, any nice -to -know facts about
alprostidyl before we move on? Well, the name
itself comes from its discovery in seminal fluid
from the prostate gland. It's also used for erectile
dysfunction in adults in products like cavergect
or MEWS. Same molecule, totally different application.
Fascinating. And one other thing for kids who
are on it long -term, like for weeks while awaiting
transplant, it can cause something called cortical
proliferation, which is a weird thickening of
the long bones. It's reversible, but something
to know. OK, so I'll process until jams the door
open, but let's flip the script. Sometimes we
have the opposite problem. The heart is structurally
normal, but the baby is premature and the ductus
won't close. Right. This is the classic patent
ductus arteriosus or PDA. In a preemie, the lungs
are incredibly fragile. If that duct stays open,
high -pressure blood from the aorta floods into
the low -pressure pulmonary artery. It's called
pulmonary overcirculation. Exactly. The lungs
get wet, heavy, boggy, the baby needs more ventilator
support, and the heart eventually fails trying
to pump against all that extra flow. So we need
to do the opposite of alprostidol. We need to
close it. Enter drug number two, indomethacin.
Indomethacin, an NSAI. It's in the same family
as ibuprofen or motrin. But we aren't giving
it for a headache or a fever. No. We are using
its primary mechanism of action as our therapeutic
effect. Indomethacin is an inhibitor of cyclooxygenase
enzymes, QOX1 and QOX2. And QS enzymes are the
factories that build prostaglandins. I see you're
making the connection. Yes. Alprostidyl is a
prostaglandin. It keeps the duct open. Indomethacin
stops the body from making prostaglandins in
the first place. Exactly. You fire the construction
crew. No COX enzymes, no prostaglandins. And
since the ductus needs a constant supply of prostaglandins
to stay open without them, it loses its signal
and it constricts. It's a chemical clamp. It
sounds brilliant, but looking at the safety data...
Endomethacin feels like a dirty drug. It hits
a lot of different systems. It does. It's not
a precision weapon. It's more like a shotgun.
Yeah. And the two battlegrounds you have to watch
very, very closely are the kidneys and the gut.
Why the kidneys? What's the link? Because prostaglandins
play a huge role in maintaining blood flow to
the kidneys, especially in a fragile, stressed
newborn. They keep the renal arteries dilated.
When you give endomethacin and wipe out the prostaglandins
to close the heart duct, You inadvertently clamp
down on the renal arteries, too. You do. You
can cause a significant reduction in renal blood
flow, leading to an acute kidney injury. So what's
the nursing implication? What do I monitor? Urine
output. Meticulously. You're calculating it every
hour. If the urine output drops, if you see oliguria,
or if the baby becomes an uric with no urine
at all, you have to hold the drug. You also monitor
the serum creatinine. If it's elevated, that's
a red flag. So the exam question might describe
a preemie with a PDA scheduled for endomethacin,
but their creatinine is high and their UOP is
low. And the answer is, hold the drug and notify
the provider. You cannot sacrifice the kidneys
just to close the duct. You might have to go
to surgical ligation instead. OK, that's the
kidneys. Now the gut. Same mechanism. Reduced
blood flow, this time to the intestines. In a
premature baby, this is the absolute nightmare
scenario. NEC. Necrotizing enterocolitis. Where
the bowel tissue literally dies. It dies because
it isn't getting enough blood. Bacteria invade
the bowel wall and the gut can perforate, spilling
stool into the abdomen. It's a surgical emergency
with a high mortality rate. So as a nurse, what
am I looking for? A distended, firm, shiny belly.
Bloody stools, you might need to do a guayac
test on the stool. Vomiting, especially green,
bilious vomit. Any of those signs are a hard
stop. So the big contraindications are active
bleeding, like an intraventricular hemorrhage,
existing kidney problems, or any signs of NEC?
Correct. You have to assess for those things
before every single dose. What about the therapeutic
effect? How do you know it worked? You listen
to the heart. A PDA has a very characteristic
machinery -like murmur. After a course of endomethacin,
that murmur should be gone. You'll also see the
baby's respiratory status improve. They'll need
less ventilator support because their lungs aren't
flooded anymore. Is there anything in the nice
-to -know category for endomethacin? Yeah, another
5e NSAI called ibuprofen lysine is sometimes
used as an alternative. Some studies suggest
it might have slightly fewer renal side effects,
but endomethacin is still the classic prototype
you'll see on exams. And it can mask a fever,
right, since it's an anti -inflammatory? It can.
You can't rely on temperature as your only sign
of infection in a baby getting this drug. You
have to look at the whole clinical picture. Okay,
so ductal dynamics in a nutshell. All prostidyl
opens the door but might stop the breathing.
Endomethacin slams the door but might starve
the kidneys and gut. That's the 80 -20 right
there. Understand that prostaglandin switch and
you understand both drugs. Perfect. Let's move
to section two. The failure fixers. We've managed
the plumbing, the ductus, but now we have to
deal with the pump itself. A lot of these kids,
whether they have a hole in the heart, like a
large VSD or an AV canal defect, they have a
heart that is just boggy. It's volume overloaded.
They're in heart failure. And it looks just like
adult heart failure, but in a tiny body. You
see periorbital edema puffy eyes to chipnia.
So rapid breeding and a classic sign in babies
is sweating while feeding. Diaphoresis. with
feeding. That's the term. It's like they're running
a marathon just to drink a bottle. It's a huge
red flag. And they fail to thrive because all
their calories are being burned just to breathe
and pump. The heart is just drowning in fluid.
So our first job is to unload the wagon. And
that brings us to drug number three, the gold
standard for this, furosemide. Lasix, the absolute
workhorse of pediatric cardiology. The class
is a loop diuretic. Let's break down the mechanism
of action in simple terms. How does it actually
get fluid out of the body? It works in a specific
part of the kidney called the ascending loop
of Henlo. In that spot, it blocks a transporter
protein that's responsible for reabsorbing sodium,
chloride, and potassium back into the blood.
And water follows salt? Water always follows
salt. If the kidney can't reabsorb the salt,
the salt stays in the urine, the water stays
with it, and the baby just pees out a huge volume
of fluid. Simple enough. You give the drug, the
diaper gets heavy, the lungs get clearer, the
breathing gets easier. That's the therapeutic
effect we want. Right. Decreased edema, clearer
lung sounds on auscultation, and an improved
work of breathing. But diuretics, especially
loop diuretics, are famous for messing with electrolytes.
What is the specific imbalance we are terrified
of with Lasix? Potassium. Lasix is a potent potassium
-wasting diuretic. It kicks potassium out right
along with the water. You are at a very high
risk for hypoklemia, low potassium. And why does
low potassium matter so much for these cardiac
kids? Two big reasons. First, low potassium makes
the heart muscle irritable. It can cause arrhythmias,
PVCs, even more dangerous rhythms. But the second
reason is a classic drug interaction that is
pure exam gold. Digoxin. Digoxin. Many of these
heart failure kids are also on digoxin to help
the heart squeeze more effectively. And I remember
this from nursing school, potassium and digoxin
compete. They compete for the same binding sites
on the heart muscle. Think of it like a game
of musical chairs. If potassium levels are normal,
there's healthy competition. But if potassium
is low, there are all these empty chairs and
digoxin can just bind everywhere way too aggressively.
And you get digoxin toxicity. You get dig toxicity.
And the earliest signs in an infant are often
GI related. Vomiting is number one, not just
spitting up, but real vomiting. So the nursing
algorithm, the exam question is, a child on Lasix
and Digoxin starts vomiting. Your first action
is? Check a potassium level immediately. Do not
just assume it's the flu or reflux. Vomiting
is often the first and only sign of dig toxicity
in an infant. So as the nurse, you're monitoring
serum potassium levels like a hawk, and you're
probably administering potassium supplements
like Kdur or IV potassium chloride. Constantly.
It's a daily battle to keep their potassium in
the normal range. There's another major safety
warning here for Lasix that I think a lot of
people miss. The monograph highlights ototoxicity.
Yes. Hearing loss. This is almost always associated
with IV administration and specifically with
pushing it too fast. How does that happen? If
you slam IV Lasix, it rapidly alters the electrolyte
balance in the fluid of the inner ear, the endolith.
That sudden shift can damage the delicate hair
cells that are responsible for hearing. And is
that damage permanent? It can be. Often it's
transient. But do you really want to be the nurse
who made a child deaf because you didn't want
to stand at the bedside for two extra minutes?
Absolutely not. So what is the speed limit? The
rule of thumb for pediatrics is you do not exceed
0 .5 milligrams per kilogram per minute. For
a bigger kid with a high dose, you are not slamming
it in like a saline flush. You are pushing it
slowly over several minutes. Or putting it on
a pump. If the dose is large enough, we often
just put it on a syringe pump to run over 10
or 15 minutes just to be absolutely safe. Slow
and steady saves the hearing. Okay, we've diareased
them. We've lowered the preload, the amount of
volume filling the heart. Now we need to help
that tired heart push blood out. We need to lower
the resistance it's pushing against. We need
to reduce the afterload. Which brings us to drug
number four, Lysinople. An AC inhibitor. That
stands for angiotensin converting enzyme inhibitor.
Right. So this drug's mechanism is blocking the
conversion of angiotensin I to angiotensin II.
And angiotensin II is one of the most potent
vasoconstrictors the body makes. It clamps vessels
down tight, which jacks up the blood pressure.
By blocking its production, Lisinopril lets the
arteries and veins relax and dilate. So it lowers
the blood pressure. It lowers the blood pressure,
which makes it much easier for a Wink failing
hard to empty its chamber. It's like trying to
push open a heavy spring -loaded door versus
a door that's already wide open. It reduces the
heart's workload. Now, let's contrast this with
Lasix. We just said Lasix dumps potassium. What
does lisinopril do to potassium? It does the
exact opposite. ACE inhibitors are potassium
sparing. By blocking part of the hormonal cascade,
they decrease aldosterone levels, and aldosterone
is what tells the kidneys to excrete potassium.
so they make the kidneys hold on to potassium.
So we have a perfect balancing act. The Lasix
is pushing potassium out. The Lisinopril is holding
it in. In an ideal world, they cancel each other
out beautifully. But you have to monitor the
lapse. You can't just blindly give potassium
supplements if, say, the Lasix is held for a
day, but the Lisinopril is still given. You could
easily swing them into hyperkalemia. And high
potassium is just as dangerous as low potassium.
It can cause fatal arrhythmias. It stops the
heart. OK. There are two other classic exam favorite
side effects for ACE inhibitors. One involves
the face. Angioedema. And the other involves
teenagers. Let's do the face first. Angioedema
is a rare but life -threatening allergic reaction
where the lips, tongue, and airway can swell
up. It can happen after the very first dose or
after years of being on the drug. So if a parent
calls and says his lips look weird and puffy
after his new heart medicine. That is a 9 -on
-1 call. That is a medical emergency. They need
to go to the ER immediately. And the teenagers.
Teratogenicity. It's a huge one. ACE inhibitors
are a boxed warning for fetal toxicity. They
are absolutely contraindicated in pregnancy.
They cause fetal renal failure and death. Yes.
So we're in pediatrics, and we often forget to
think about this. But if you have a 16 -year
-old girl with cardiomyopathy who is on Lisinopril.
You have to have the awkward conversation. You
have to. She cannot get pregnant while on this
drug. It is category X. If she's sexually active,
she needs reliable contraception. It is a mandatory
part of your nursing education and documentation
for all adolescent females of childbearing potential.
It's a huge liability point. OK, Lasix and Lisinopril
are sort of the daily maintenance crew. But sometimes,
especially post -op, you need a heavy hitter
to control acute hypertension. That's drug number
five, hydrolazine. Hydrolazine is a direct acting
vasodilator. It doesn't mess around with the
whole RAAS system like ACE inhibitors do. It
goes straight to the smooth muscle in the arteries
and tells it to relax. And its effect is pretty
rapid. Very rapid, especially the IV form. It
decreases systemic resistance and lowers blood
pressure fast. We use it a lot for post -op cardiac
kids who come back from the OR with hypertension.
But the body has a compensatory mechanism, right?
You drop the pressure suddenly and the body panics.
It does. It's called reflex tachycardia. The
body's baroreceptors sense the sudden drop in
pressure and they send an uh -oh signal to the
brain. The brain then tells the heart to beat
faster to try and bring the pressure back up.
So you give IV hydrolazine, the blood pressure
beautifully drops from 110 down to 90. But the
heart rate spikes from 120 to 150. Is that considered
a failure of the drug? No, it's an expected physiological
response. We anticipate it. Yeah. But you need
to monitor for it. And often these patients are
also on a beta blocker, which helps to blunt
that tachycardic spike. I found a weird nursing
tip in the notes for hydrolazine regarding its
interaction with metal. Yes. This is an old school,
but vital piece of information. Hydrolazine can
undergo a chemical change. It degrades and changes
color if it sits in contact with metal for too
long, like in a stainless steel medicine cup,
or if drawn up with a metal needle and left to
sit. So the rule is you don't pre -draw this
medication and leave it on the counter for an
hour. Never. You draw it up and you give it immediately.
If you notice it's changed color, you have to
toss it. It's a sign of chemical degradation
and loss of potency. All right, that covers our
failure fixers. Let's shift gears to section
three, scenario specifics. We are moving away
from general heart failure and looking at specific,
terrifying events that happen with certain defects.
Let's talk about the Tet spell. The hypersynotic
spell. This is the hallmark of Tetralogy of Fallot,
or TOF. Okay, quickly, what is the core problem
in TOF? You have four defects, but the one that
matters for spells is a narrowing of the pathway
to the lungs. Pulmonary stenosis, combined with
a big hole between the ventricles. A VSD. So
describe the physiology of a spell. What is actually
happening? So that pathway to the lungs is already
narrow, but sometimes usually during an event
that increases oxygen demand like crying, feeding,
or having a bowel movement, the muscle right
below that narrow valve, it's called the infundibulum,
goes into a sudden severe spasm. It's like a
fist closing around the hose to the lungs. That
is a perfect analogy. It clamps shut. Now, deoxygenated
blood coming into the right ventricle has nowhere
to go. It can't get to the lungs, so it takes
the path of least resistance, which is across
the VSD into the left ventricle and out to the
body. But this is blue, unoxygenated blood. Exactly.
So the baby turns a deep, profound blue or purple
almost instantly. Their oxygen saturation plummets
into the 30s or 40s. It is terrifying to watch.
We need a drug to break that spasm. Enter drug
number six, propranolol. Propranolol is a non
-selective beta blocker. It blocks the effects
of adrenaline and the sympathetic nervous system
on beta -1 receptors in the heart and beta -2
receptors elsewhere. How does that help break
the spell? By blocking the beta -1 receptors,
it slows the heart rate and, crucially, it reduces
the voice of contraction. It relaxes that spasming,
infundibular muscle. It loosens the fist. The
pathway to the lungs opens back up. It opens
back up. Blood can flow to the lungs again, and
the baby turns pink. So propranolol is usually
given as a daily maintenance drug to prevent
these spells from happening in the first place.
Correct. But let's simulate the emergency. You're
the nurse. A baby having a tet spell is in front
of you. Do you run for the propranolol first?
No. Absolutely not. The very first thing you
do is change the physics of the situation. You
put the baby in the knees to chest position.
You take the baby's knees and you push them up
firmly against their chest. Why does that work?
It kinks the femoral arteries in the legs. This
dramatically increases the systemic vascular
resistance, or SVR. By making it harder for blood
to flow down to the legs, you increase the pressure
on the left side of the heart. This encourages
the blood in the right ventricle to choose the
now easier path to the lungs instead of shunting
across the VSD. So it's a mechanical fix. It's
a mechanical fix. So it's knees to chest, try
to calm the infant, apply oxygen, and then you
might give IV morphine, which also helps relax
the spasm. Perpranolol would be more of a second
line IV intervention in the acute spell, but
its primary role is prevention. You mentioned
propranolol is non -selective. That means it
hits beta -1 and beta -2 receptors. Which is
a major problem if your cardiac kid also has
a history of asthma. Why? Because the beta -2
receptors are what keep the airways the bronchioles
open. If you block them with propranolol, you
can trigger a severe bronchospasm, a massive
asthma attack. So an absolute key nursing consideration
is to check the patient's respiratory history.
Cardiac kid plus asthma, propranolol is probably
not the right choice. You'd want to use a cardioselective
beta blocker instead, like metoprolol or atenolol,
which primarily hits beta 1. There's one more
tricky interaction with propranolol that is a
favorite for exams, diabetes. Yes. Beta blockers
mask the signs of hypoglycemia. Normally when
your blood sugar drops your sympathetic nervous
system kicks in. You get jittery, sweaty, and
your heart races. That's your body's alarm bell
telling you to eat. But beta blockers stop the
jitters and the tachycardia. They block that
whole response. Yes. So a diabetic child on propranolol
could have their blood sugar drop to a dangerously
low level without anyone noticing until they
become lethargic or even have a seizure. So you
have to be hypervigilant with blood sugar monitoring
in that specific population. You absolutely do.
OK, let's talk about the other big scenario,
clots. Kids with complex heart defects are full
of plastic tubes, artificial shunts, patches,
and areas of sluggish blood flow. All of this
is a recipe for thrombosis. Which brings us to
heparin, drug number seven. Heparin is an anticoagulant.
Its mechanism is that it potentiates the body's
own natural anti -clotting factor, antithrombin
the third. Right. It basically supercharges antithrombin
the third, making it hundreds of times more effective
at inactivating thrombin and other clotting factors.
It doesn't break down existing clots, but it
stops them from getting bigger and prevents new
ones from forming. We use this a lot after surgeries,
especially with palliative shunts like the BT
shunt. A Blalock tossing shunt is a tiny Gore
-Tex tube, maybe three or four millimeters wide,
that connects an artery from the aorta to the
pulmonary artery. It's a lifeline for babies
who need more pulmonary blood flow. If that tiny
tube clots off, the baby dies. Heparin is critical
to keep it patent. The primary risk, obviously,
is bleeding. But I want to focus on the fatal
error warning mentioned in the sources. This
is something that has tragically killed patients.
The concentration error. This is one of the most
feared medication errors in all of nursing. Heparin
comes in vials that can look frighteningly similar
but have vastly different strengths. You have
the flush concentration. Which is very dilute.
Maybe 10 units per ml or 100 units per ml. It's
used just to keep IV and central lines from clogging
up between uses. And then you have the systemic
or therapeutic file. Which can be 1 ,000 units
per ml. 5 ,000 or even 10 ,000 units per ml.
That is a potential 1 ,000 -fold difference in
concentration. And if you grab the 10 ,000 -unit
vial thinking it's the 10 -unit flesh? You give
a massive overdose. You effectively exsanguinate
the patient internally. Their blood becomes unable
to clot at all. In a tiny neonate, this is almost
always fatal. It's caused well -publicized deaths.
This is why heparin is a mandatory two -nurse
check in almost every hospital in the country.
It has to be. You have to physically get a second
licensed person, show them the vial, read the
concentration out loud, and show them your calculation.
I have heparin, 10 ,000 units per mL. The order
is for 100 units. I have drawn up 0 .01 mLs.
They have to verify every step. And you can't
rely on the color of the cap. Absolutely not.
Manufacturers change cap colors all the time.
You have to read the words on the label. If you
do make a mistake or if the patient just starts
hemorrhaging for other reasons while on heparin,
is there an undo button? There is. It's protamine
sulfate. That is the specific antidote for heparin.
It binds directly to the heparin molecule and
neutralizes it. You need to know where that is
kept on your unit, because when you need it,
you need it now. And what are you monitoring
for a patient on a continuous heparin infusion?
The APTT, or activated partial thromboplastin
time. That lab value tells you how long it takes
the blood to clot and you adjust the heparin
drip rate up or down to keep the APTT within
a specific therapeutic range. Okay, we are in
the homestretch. Section four, the acquired heart
disease meds. These are kids born with structurally
normal hearts who get sick. We have a trio here.
Kawasaki disease, rheumatic fever, and infective
endocarditis. Right. These are inflammatory or
infectious processes that attack the heart. Let's
start with Kawasaki disease. This is the vasculitis
known for the high fever, the rash, the strawberry
tongue. The real danger with Kawasaki is not
the rash or the fever. It's that the immune system
launches a massive inflammatory attack on the
blood vessels, and it has a scary affinity for
the coronary arteries. The arteries that feed
the heart muscle itself. Yes. It can cause coronary
artery aneurysms weak, ballooning spots in the
vessels. These can lead to blood quats, heart
attacks, and sudden death even years later. And
the treatment regimen for Kawasaki involves two
key things, one of which is a drug we are rigorously
taught never to give to children. Aspirin. Right.
Every nursing student learns that giving aspirin
to a child with a viral illness can cause Ray's
syndrome, a devastating condition that causes
litter failure and brain swelling. And that is
absolutely true. But Kawasaki is the one major
exception to that rule. The risk of a permanent
coronary artery aneurysm is so high. and the
anti -inflammatory and anti -platelet effects
of aspirin are so beneficial that we accept the
small risk of raise. So we give very high doses
of aspirin initially to cool down the inflammation
and then a low dose for a long time to prevent
clots. Exactly. And the second part of the treatment
is a massive dose of IVIG intravenous immunoglobulin.
What's the thinking there? IVIG. is a product
made from the pooled antibodies of thousands
of blood donors. Giving a huge dose of it seems
to reset or modulate the patient's own haywire
immune system, stopping it from attacking the
blood vessels. It dramatically reduces the incidence
of coronary aneurysms. But there is a logistical
catch with IVIG that's a big deal for pediatric
nurses. It messes with vaccines. It does. Because
IVIG is just a soup of antibodies, if you give
a child a live vaccine, like the MMR for measles,
mumps, rubella, or the varicella vaccine for
chickenpox, right after they've received IVIG.
The antibodies in the IVIG will just attack and
kill the weakened vaccine virus. And the child's
body never gets a chance to build its own immunity.
The vaccine just won't take. So what's the rule?
The rule is you must delay all live virus vaccines
for 11 months after the IVIG infusion. This is
a huge teaching point for parents at discharge.
You have to make sure they understand why their
child's vaccine schedule is being altered. Okay.
Finally, let's touch on rheumatic fever and infective
endocarditis. These are both bacterial in origin.
Correct. Rheumatic fever is a post -infectious
complication of untreated group A strep throat.
Endocarditis is a direct bacterial infection
of the heart lining or valves. The 80 -20 here
seems to be about the duration of antibiotic
therapy. These are not your typical five -day
courses of amoxicillin. Not even close. For infective
endocarditis, you have these clumps of bacteria
called vegetations growing on a heart valve.
It's incredibly difficult for antibiotics to
penetrate that biofilm. These kids need four
to eight weeks of high -dose IV antibiotics,
usually something strong like penicillin G or
vancomycin. So they are going home with a PICC
line and home health nursing. It's a huge commitment
for the family. And for romantic fever, the issue
is preventing recurrence. If you've had it once,
your heart valves can be damaged and you're very
susceptible to getting it again with another
strep infection. So these patients need long
-term prophylaxis? Yes. They might be on monthly
injections of long -acting penicillin until they
are 21 years old, or sometimes even for life,
to protect their heart valves from further damage.
It's a huge burden. OK, so looking back at this
entire roadmap, we've covered a lot of ground.
We have the ductal duo. Alprostidyl and indomethacin.
The opener and the closer. Watch the breathing
for the opener. Watch the kidneys for the closer.
Exactly. Then we have... The failure fixers,
Lasix and Lisinopril. Watch the potassium. It's
a seesaw. Lasix wastes it. Lisinopril saves it.
And always, always check a potassium level. If
a baby on digoxin starts vomiting. We have the
scenario managers, proprinol for tet spells,
heparin for clots. Knees to chest first for the
spell. And read the vial out loud for the heparin.
Twice. And finally, the acquired trio, where
we break the aspirin rule for Kawasaki and give
IV antibiotics for weeks on end. What is the
big so what here? Why does this specific level
of detail actually matter at the bedside? Because
the margin for error in a three kilogram baby
is non -existent. A misplaced decimal point in
a dose calculation isn't just a paperwork problem,
it's a stroke. It's renal failure. It's a dead
baby. It's about anticipation. That's the word.
If you know alprostedil causes apnea, you aren't
staring at the monitor in shock when the alarm
goes off. You are already standing there with
the bag -salve mask in your hand. You move from
being reactive to being proactive. That is what
saves lives. And before we wrap up, I want to
leave you with one final thought that really
struck me while researching alprostedil. We treat
these drugs like these very sterile industrial
chemicals. But nature is incredibly efficient.
Do you know where prostaglandins were first discovered?
In seminal fluid. Hence the name, prostaglandin.
It was first isolated from the prostate gland.
The exact same molecule that biology uses for
reproduction is the molecule we use to keep a
blue baby alive until surgery. And it's the same
molecule used in drugs like cavergect for adult
erectile dysfunction. It's just a tool. It's
just keys and locks. The body reuses the same
key for different doors. It just makes you wonder
what other off -label miracles are sitting in
our pharmacy right now, just waiting for someone
to figure out that a key for one condition fits
a completely different lock somewhere else. It's
a fascinating field. Biology is always smarter
than we are. We're just trying to catch up to
its designs. Keep your drips timed. Check your
math twice. And trust your gut. We'll see you
in the next deep dive.