Chapter 35: Critical Care of Patients With Acute Coronary Syndromes

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Welcome to the Deep Dive.

We're taking a really focused look today at acute coronary syndromes, or ACS.

Essentially the critical nursing care involved when someone's heart is acutely under threat.

We're aiming to give you that essential overview based on a core medical surgical text.

Exactly.

Think of this as your guide through a life or death situation.

And guiding our whole discussion today are two main concepts.

Number one priority,

perfusion, getting that blood flow back.

Absolutely critical.

And tied right into that signaling the crisis is pain.

And that focus on perfusion, it's just non -negotiable.

You know, coronary artery disease, CAD, it's still the biggest killer in the U .S.

Still number one.

Yeah.

And when perfusion stops, the damage starts, well, immediately.

But the actual signs of dead tissue, the infarction, they don't really show up clearly for about six hours.

Wow, six hours.

Right.

So that window, that crucial time for intervention, is really within the first four to six hours after symptoms begin.

Like we always say, time is myocardium.

Okay, so let's lay the groundwork.

CAD itself, coronary artery disease.

We're talking about the arteries feeding the heart muscle, right?

That's it.

And the chapter maps out this spectrum.

It starts with ischemia, basically, a temporary oxygen shortage.

Reversible, hopefully.

Hopefully.

And at the other end, infarction.

That's the irreversible bit.

Necrosis, cell death.

Game over for those cells.

So on the, let's say, milder end of the comfort.

Comes on with a certain amount of exertion, maybe walking up a hill.

Familiar pattern.

Exactly.

They know it.

They might take nitroglycerin or just rest.

And crucially, it goes away.

It's a warning sign, definitely, but stable.

But then things escalate.

We hit acute coronary syndrome, ACS.

Yep.

And the trigger here, it's fascinating.

It's not just the gunk of the pipes.

It's the rupture of that atherosclerotic plaque.

That's the key event.

The plaque breaks open.

The inside of the artery wall is exposed.

And bam, platelets rush in.

A clot starts forming.

The artery clamps down.

Veto constriction, right?

Yep.

And the text says, once you hit about 50 % blockage, blood flow is seriously, seriously compromised.

Okay.

So that rupture leads us to the unstable situations.

First, unstable angina, UA.

How is this different from the stable kind?

Well, the pain's worse for starters.

It can happen even when you're resting or with very little effort.

Lasts longer, maybe more than 15 minutes.

And the nitroglycerin doesn't work as well.

Exactly.

Poorly relieved by NTG or rest.

Now, on the ECG, you might see some changes.

ST depression, maybe.

T wave inversion.

But here's the kicker.

Initially, those cardiac markers, the troponins, they haven't gone up yet.

So ischemia is happening, but we haven't confirmed actual cell death yet.

Precisely.

It's unstable.

It's dangerous, but maybe not full infarction at that exact moment.

Okay.

So if that blockage gets worse or is already total, we get to myocardial infarction, MI.

And the ECG is what splits this into two types.

That's right.

It all comes down to the ST segment on that ECG.

You've got NSTEMI, non -ST elevation MI.

Here you see ST depression or T wave inversion, signs of significant ischemia.

And then over the next, say, three to 12 hours, the troponins do start to rise.

That confirms necrosis happened.

The artery isn't necessarily 100 % blocked, but damage occurred.

But the big one, the code red emergency, is the STEMI, ST elevation MI.

That's the one.

ST elevation in two adjacent leads on the ECG.

That tells you right then and there, you've got an abrupt total 100 % blockage of a coronary artery.

100%.

A big area of heart muscle is dying right now, needs immediate reperfusion, open that artery fast.

And if we don't open it fast enough,

what's the long -term consequence of that dead tissue?

You know, it's irreversible.

Yeah.

And this is so important clinically.

The dead area, the infarct, eventually scars over, but scar tissue doesn't pump.

Right.

And the scarring changes the actual size and shape of the left ventricle over time.

It's called ventricular remodeling.

The heart gets weaker, less efficient, and that's the path towards heart failure later on.

Minimizing that remodeling is a huge goal of treatment.

Got it.

So if atherosclerosis is the root cause, let's talk risks.

We know the usual suspects,

smoking,

diet, but is there a cluster of factors that really speeds this up?

Oh, absolutely.

The chapter highlights metabolic syndrome, sometimes called syndrome X.

It's not just one thing.

It's like a dangerous combination.

Convergence.

Exactly.

Usually involves things like a large waist circumference, central obesity, plus high blood pressure, plus high fasting blood sugar.

Get three of those indicators and your risk for CAD and ACS just skyrockets.

We also need to touch on gender.

The text points out some really important differences, especially in how symptoms present.

Yes, definitely.

Women tend to get CAD later, maybe 10 years older than men on average, but, and this is critical, if they have an MI, their risk of dying within that first year is actually higher.

Higher.

Yeah.

And part of the challenge is that many women experience what's called atypical angina, not the classic elephant on the chest.

What do they feel?

It could be really vague stuff, like unusual fatigue that can't explain, shortness of breath, maybe indigestion, or pain just between the shoulder blades, or an aching jaw.

Clinicians have got to have a high index of suspicion for these atypical symptoms.

That atypical presentation makes rapid assessment even more crucial.

Someone comes into the ED with chest discomfort.

What's the absolute first time critical diagnostic step?

Get an ECG, period.

And the standard, the quality measure, is within 10 minutes of arrival.

10 minutes.

That fast.

Yep.

That ECG is our first big clue.

Is it a stemma?

Where's the potential damage?

Meeting that 10 minute goal makes a huge difference in outcomes.

And while that's happening, we're drawing blood for labs.

You got it.

Specifically looking for troponin T and troponin I, these are super specific markers for heart muscle damage, for necrosis.

But they take time to rise, right?

You said three to 12 hours.

Exactly.

So you get a baseline level right away, but then you have to repeat the test, do serial troponins to see if they're going up.

That trend confirms the diagnosis, especially if the ECG wasn't a clear stemmy initially.

Okay.

Assessment done.

Diagnosis firming up.

Now, management.

We've got ACS.

Two main goals, you said.

Manage pain, restore perfusion.

Let's hit pain first.

Less pain equals less stress on the heart.

Right.

And the cornerstone here is nitroglycerin, NTG.

It's clever how it works.

It dilates coronary arteries, helps collateral flow, but it also reduces preload and afterload.

So it makes the heart's job easier.

Precisely.

Less work for a struggling muscle.

But there's a critical safety check with the NCG administration, right?

The protocol?

Absolutely paramount.

You give a dose, sublingual usually, wait five minutes, reassess their pain, check their blood pressure, still hurting.

Give another dose, wait five minutes, check again.

And max of three doses.

Max of three.

If they still have significant pain after three doses, five minutes apart, you have to assume it's a full MI.

Prepare for urgent intervention.

And the other huge safety alert.

Oh yeah.

You must ask if they've taken any phosphodiesterase inhibitors recently, drugs like sildanafil for erectile dysfunction, within the last 24 to 48 hours.

Because combining those with NTG can cause a catastrophic drop in blood pressure.

Profound hypotension.

Absolutely contraindicated.

Big red flag.

Okay.

Good to know.

If NTG isn't enough for the pain.

Then we move to morphine sulfate.

Usually a small dose, maybe two to four milligrams given slowly IV.

It's great for pain, but it also helps reduce that myocardial oxygen demand a bit too.

What about oxygen itself?

Do we just put everyone on it?

We used to, pretty much routinely, but the thinking shifted.

The text emphasizes,

only give oxygen if their O2 saturation is below 90%.

Really?

Why not just give it?

Because if they're not actually hypoxemic, extra oxygen might, paradoxically, cause coronary vasoconstriction and potentially worsen things.

So targeted use based on saturation.

Okay.

Pain addressed.

Now the main event,

increasing myocardial perfusion, getting that artery open,

starts with antiplatelets.

Immediately.

Everyone with suspected ACS gets aspirin, chewed ideally for faster absorption.

325 milligrams.

It stops platelets from clumping together.

And the advice for someone at home having new chest pain?

Chew that aspirin.

325 milligrams and call 9 -1 -1.

Don't drive yourself.

Call 9 -1 -1.

Then in the hospital, they often get more antiplatelet power.

Yep.

Usually dual antiplatelet therapy or BAPT.

That's aspirin plus another agent, like clopidogrel or ticagrelor.

These are P2I -12 inhibitors.

More potent clot prevention, but obviously increases bleeding risk too.

Makes sense.

What other meds are standard in this acute phase?

Beta blockers are really important.

They've been shown to decrease the and improve survival.

But another safety check here.

Always.

Don't give a beta blocker if their heart rate is already low, say under 50, or if their systolic blood pressure is under 100.

Gotta be cautious.

And then something for that remodeling we talked about.

Yes.

ACE inhibitors, or ARBs, usually started within 24 hours.

They specifically help prevent that negative ventricular remodeling and reduce the risk of developing heart failure.

Okay, drugs on board.

Now the definitive reperfusion strategies.

For a STEMI, the clock is ticking loudest.

Loudest and fastest.

Time is myocardium.

The gold standard for STEMI is percutaneous coronary intervention, PCI.

That's the angioplasty and stent procedure.

Exactly.

Go in with a catheter, retrieve the clot,

inflate a balloon to open the artery, place a stent to keep it open, and the goal,

door to balloon time,

within 90 minutes of arrival.

90 minutes.

That requires a really slick system.

It absolutely does.

What if a hospital doesn't have a cath lab or can't meet that 90 -minute window?

Then plan B is fibrinolytic therapy, clot -busting drugs, thrombolytics.

The goal here is door to needle time within 30 minutes of arrival.

Faster goal, but more risks.

Definitely more bleeding risk because it affects clotting everywhere, not just in the heart.

So lots of contraindications like recent surgery, stroke, active bleeding, prior intracranial hemorrhage.

You have to screen patients very carefully.

And if the fibrinolytics work, how do you know?

You look for signs of reperfusion.

Sometimes the chest pain just abruptly stops.

You might see the ST elevation start to come down on the ECG.

And interestingly, you can sometimes get a sudden burst of ventricular dysrhythmias as blood flow returns to the stunned heart muscle.

Okay.

Artery open, hopefully.

But the danger isn't over.

Post -MY complications are common.

What's the biggest killer before they even get to the hospital?

Dysrhythmias.

Legal heart rhythms.

That's the leading cause of pre -hospital death.

And does the location of the MI affect the type of dysrhythmia?

It often does.

MIs affecting the front wall, the anterior MIs, tend to make the ventricle irritable, think frequent PVCs, maybe even V -tach or V -fib.

And inferior MIs.

They're closer to the heart's natural pacemaker and conduction system.

So you're more likely to see slow heart rates, brady partias, and AV blocks.

Makes sense.

In the hospital, the most feared complication is probably severe heart failure,

up to cardiogenic shock.

Yes.

Cardiogenic shock.

That's the worst -case scenario.

The text uses the Killip classification check.

Class 4 is cardiogenic shock.

It means more than 40 % of the left ventricle muscle is necrotic, dead.

40%.

That's massive damage.

Catastrophic.

The heart just can't pump effectively anymore.

What are the critical signs nurses need to spot immediately?

The critical rescue signs.

You'll see persistent tachycardia trying to compensate, but profound hypotension systolic, usually below 90.

Skin gets cold, clammy.

They become confused because the brain isn't getting enough oxygen.

And you'll see signs of fluid backing up into the lungs, pulmonary congestion.

Early recognition is absolutely vital.

If drugs aren't enough to support the blood pressure in shock, what mechanical support might be used?

The text mentions the IABP.

Right.

The intraaortic balloon pump, IABP.

It's a temporary measure, a bridge.

It's a balloon inserted into the aorta.

How does it help?

It's all about timing.

It inflates during diastole when the heart rests.

This pushes blood backward into the coronary arteries, improving oxygen supply to the heart muscle itself.

Then, right before the heart beats, systole, it rapidly deflates.

This creates a sort of vacuum effect, reducing the resistance the weak ventricle has to pump against that's reducing afterload.

It basically gives the heart an assist.

Clever.

And managing these critically ill patients requires really detailed monitoring.

Oh, absolutely.

Invasive hemodynamic monitoring is standard, usually with a pulmonary artery catheter, sometimes called a swangans.

What is that measure?

It gives us real -time pressures from inside the heart and pulmonary artery, right, atrial pressure, pulmonary artery pressure, and the key one, pulmonary artery occlusion pressure, or PAUP, which reflects left ventricular filling pressure.

These numbers tell us exactly how the heart is handling fluids and guide our use of fluids, diuretics, and vasoactive drugs very precisely.

So intensive care, mechanical support,

but sometimes even that isn't enough, or the blockages are too widespread for stents, and surgery is considered.

Right, coronary artery bypass graft surgery, or CABG.

This is usually for patients who failed medical management, didn't get good results with PCI, or have really severe disease, like major blockage in that critical left main coronary artery.

What's key for nurses before the surgery?

Pre -op teaching.

Hugely important.

Patients need to know how to protect their sternal incisions splinting with a pillow when coughing.

They need to practice deep breathing and coughing exercises before surgery to help prevent lung complications like pneumonia afterwards, and stressing early walking, early ambulation to prevent blood clots.

And then after surgery, the monitoring is intense.

What are the big things to watch for?

Fluid and electrolytes are huge, especially potassium and magnesium.

If those get out of the bag, it's a recipe for dangerous dysrhythmias.

So frequent lab checks are standard.

Bleeding.

Yes, monitoring the chest tube drainage is critical.

The rule of thumb mentioned is, if you see drainage of 150 milliliters per hour or more, notify the surgeon immediately.

That's too much bleeding.

And the really scary complication, cardiac tamponade.

Yeah, that's where blood or fluid builds up in the sac around the heart and starts squeezing it, preventing it from filling properly.

It's a surgical emergency.

How do you spot it?

The classic signs.

Look for the Beck triad.

It's three things.

One, jugular venous distension, JVD, bulging neck veins, but the lungs sound clear.

Two, heart sounds are distant, muffled.

And three, hypotension falling blood pressure.

Beck's triad means tamponade until proven otherwise.

Okay, Beck's triad.

Got it.

One last post -DABG point.

Pain.

How do you tell normal incision pain from something more sinister, like the graft failing?

Good question.

The stenotomy incision pain is usually shark localized, feels like burning, and gets worse when they cough or move.

It's expected surgical pain.

But if the patient starts describing that familiar, maybe diffuse angiol chest discomfort again, that's a red flag.

That could mean one of the bypass grafts isn't working properly, needs urgent investigation.

All right.

So the patient survives the surgery, stabilizes, they're moving towards discharge.

What's the next phase?

That's cardiac rehabilitation, usually starts even before they leave the hospital.

But phase two is key.

That's the outpatient post discharge recovery period, helping them get back to a functional life.

How does activity progress?

Gradually.

It often starts with simple things like short walks.

The text suggests maybe 400 feet, three times a day initially, then slowly increasing distance and intensity as tolerated.

What about sensitive topics like resuming sexual activity?

Important to address it.

The general guidance is if the patient can comfortably claim two flights or walk a block without getting chest pain or severe shortness of breath, it's generally safe to resume sexual activity.

Advise them to choose a time when they're rested, maybe not right after a heavy meal.

And probably the most vital piece of discharge teaching, what to do if chest pain happens again at home.

Absolutely crucial reinforcement.

The protocol is sit down immediately, take one nitroglycerin dose, wait five minutes, still have pain, call 911 immediately.

Don't wait.

While waiting for EMS, they can take a second and if needed, a third NTG dose five minutes apart.

But the call to 911 after the first dose doesn't provide relief is the critical step.

That protocol saves lives.

It really does.

You know, we spent all this time on the technical side, the ECG times, the PCI windows, Beck's triad, all incredibly important.

But pulling back the source material really makes you think about the huge psychosocial impact of having an MI.

Yeah, the fear, the denial.

Exactly.

Denial, anger, depression are all common.

And maybe the biggest challenge for us as clinicians is balancing that technical urgency hitting those time targets with real empathetic communication.

We have to connect with patients, help them work through that denial so they actually adhere to the lifestyle changes and medications that will keep them alive long term.

It's a tough balance.

That is a powerful point to end on.

Balancing the science and the human element.

So we've traced the ACS journey from plaque rupture, differentiating STEMI and ENSTEMI, through the key drugs like NTG and aspirin, the big interventions like PCI and fibrinolytics, managing complications like cardiogenic shock, and the essentials of key BG care, including watching for tamponade.

And a comprehensive look, definitely.

Thank you for joining us on this deep dive into such critical coronary care.

Hopefully this helps you feel more prepared,

stay informed, and stay ready.