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02.03 Cardiac (Heart) Enzymes

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Overview

  1. Cardiac Enzymes
    1. CK
    2. CK-MB
      1. Normal Value Range
      2. Patho / meaning
      3. Any special considerations when drawing the lab (i.e. on ice, etc.)
      4. Too High: Causes, Symptoms, Treatments
      5. Too Low: Causes, Symptoms, Treatments

Nursing Points

General

  1. CK- Creatine Kinase
    1. Normal Value Range
      1. 55-170 U/L
    2. Patho / meaning
      1. Enzymes specific to muscle
      2. If damaged or inflamed, can be released into the bloodstream
      3. Can be measured
      4. CK is not specific to cardiac muscle
      5. Has three variants
        1. CK-MM
          1. Found in skeletal muscle
        2. CK-MB
          1. Found in cardiac muscle
        3. CK-BB
          1. Found in brain tissue
    3. Special considerations
      1. Green top tube (heparin)
    4. Lab Value Elevations
      1. Indicative of muscle tissue damage
      2. Must compare to clinical symptoms
    5. Decreased lab levels
      1. Could indicate muscle weakness or muscle disease
      2. Not specific to cardiac concern
  2. CK-MB –  Creatine Kinase – Muscle/Brain
    1. Normal Value Range
      1. 0-2.4 ng/mL
    2. Patho / meaning
      1. Enzymes specific to cardiac muscle
      2. If damaged or inflamed, can be released into the bloodstream
      3. Can be measured
      4. Detectable in 3-6 hours after injury
        1. Peaks in 12-24 hours
        2. Returns to normal in 24-72 hours
        3. Can be used in lieu of troponin
    3. Special considerations
      1. Green top tube (heparin)
    4. Lab Value Elevations
      1. Indicative of cardiac  muscle tissue damage
      2. Must compare to clinical symptoms
      3. Can also occur in kidney damage

Assessment

  1. Assess for:
    1. Acute chest pain
    2. Symptoms of MI
      1. Nausea
      2. Vomiting
      3. Angina in any form
      4. Reflux (especially in women)

Therapeutic Management

  1. EKG
  2. Angiography or PCI
  3. Management of non-cardiogenic etiology

Nursing Concepts

  1. Lab Values
  2. Perfusion

Patient Education

  1. Educate patient on keeping history of elevated levels or cardiac disease for future reference
  2. Educate patient on duration of elevated CK and CK-MB levels, post injury

Reference Links

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Video Transcript

All right in this lesson we’re going to take a look at cardiac enzymes.

Now in this lesson we’re going to look at two additional cardiac enzymes aside from troponin. These two are CK and CK-MB. CK stands for creatine kinase and and it’s an enzyme found in muscles and when there is muscle damage or inflammation, this enzyme leaks into the bloodstream and it can be measured. A normal value for CK is 55 to 170, but if you have some sort of muscle damage it could go up. There are three different types of CK and they’re called ISO enzymes. There’s CK-MM, which is specific to skeletal muscle, there’s CK-MB which is specific to cardiac muscle, and there’s CK-BB which is specific to brain tissue. The one that we worry about when we’re talking about cardiac enzymes is CK overall and also ck-mb.

Now like CK the ck-mb level it’s something that we’re going to continue to watch with our cardiac patients. So if your patient is having an acute cardiac event, what you would expect us to get cardiac levels on your patient. This would be your CK, your ck-mb, and your troponin. Use all of these levels together to get a good ideas what’s going on with your patient. The normal value for ck-mb is 0 to 2.4 nanograms per deciliter, and it really should be undetectable in most patients.

But because Ck-mb is specific to cardiac muscle and just like CK, it can be released into the bloodstream if there’s damage specifically to the cardiac muscle. Is usually detectable in 3 to 6 hours and often peaks in 12 to 24 hours. It starts to return to its normal level within one to three days but the beauty of this test is that it can actually be used in lieu of troponin. So if for whatever reason you can’t get a Trope on your patient, you can send this out to get an idea as if there is some sort of cardiac event going on.

Now for this lesson because they’re used so frequently together, and they’re very close in nature, we’re going to do some comparisons between the two. For special considerations what we want to consider here is that both of these tests can be submitted in a green top tube. Like I said in the last slide, it would not be uncommon to send out a whole cardiac panel on your patient with one Green Top tube. Most laboratories can do this without a problem. But you want to make sure you check with your facility.

So what do we do if our CK or our ck-mb is high for our patients. Well the first thing we want to do is look at our patient, see what kind of injury they have. If they’re there for a trauma, you can expect the CK to be high because they probably have some sort of skeletal injury that’s going to make their CK jump up. However if their ck-mb is high, and they’re troponin Czar high, and they’re complaining of chest pain, you probably have some sort of cardiac event going on and you need to pay attention so what’s going on with your patient.

For patients who have elevations in in CK specifically, it just indicates that there’s some sort of muscle cell damage, and it’s not specific to any type. What you want to do is compare that to your patient’s clinical symptoms. Now if the CK levels are actually low it can indicate some sort of muscle weakness or maybe some sort of muscular disease like muscular dystrophy. But it’s not specific to any sort of cardiac concern if it’s low.

Because you’re ck-mb levels should be low usually at all times, That level can be elevated if there’s some for cardiac injury. Ck-mb can also go up in some instances of kidney damage your kidney failure, so that’s why I’m saying you need to pay attention to your patient’s clinical symptoms, the overall diagnosis, and the labs and the trends when you’re looking at these levels.

For this lesson, we really focused on the nursing concepts of lab values and perfusion and looking at how cardiac cell damage affect certain levels.

Okay so let’s recap.

Remember that ck-mb is the CK level that were looking at when were talking about cardiac tissue; not just CK by itself.

CK can be elevated in cardiac injury patients but it also can be due to skeletal injuries so you’re going to want to look at your patient.

Which leads me to my next point, which is to consider if your patient is symptomatic.

Ck-mb can be used any of it the troponin is not available, and you want to use your ck-mb with your troponins, so look at these trends over time.

That’s our lesson on cardiac markers. Make sure you check out all the resources attached to this lesson. Now, go out and be your best selves today. And, as always, happy nursing!!

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