Cardiac Biomarker Tests for Acute Coronary Syndrome (Nursing)

00:00 Hi! Welcome to our video series.

00:03 In this one we're going to look at the lab work and diagnostic tests for a patient with a myocardial infarction.

00:09 So when you suspect a patient could having be having acute coronary syndrome.

00:14 We're going to talk about the lab tests take a venous blood sample.

00:17 And these lab tests will help us diagnose, evaluate and monitor these patients.

00:23 Now first we're going to talk about cardiac bio markers.

00:26 But what I want you to put a little star buyers Troponin I or T, so just mark that for now what we're trying to identify we're looking to see if the heart has suffered any damage.

00:37 Now in your graphic there we have the picture of the heart.

00:40 We've got a little black into area around where the heart did not receive enough oxygenated blood and so we have dead tissue.

00:48 That's what the bio markers will tell us.

00:49 Has there been any damage to the tissue.

00:52 Troponin I and troponin T are often used.

00:55 We also have high sensitivity troponin.

00:58 We'll talk about those in just a minute.

01:00 Creatine kinase and CK-MB those guys are ones we used to use troponin is going to be more effective and sometimes myoglobin is used.

01:10 So we've given you four tests.

01:12 But the one I want you to really remember is the one troponin.

01:15 That's the most important one for our discussion.

01:18 So troponin are the most commonly ordered and most specific of the bio markers.

01:24 So the other ones can be helpful, but troponin is going to be the most specific.

01:28 Now this is a group of proteins.

01:30 They're found in skeletal and cardiac muscle and they control can muscle contraction.

01:35 So what are troponins? They are group of proteins, we find it in skeletal and cardiac muscle.

01:42 There are what help control muscular contractions.

01:45 They usually very small amounts are present in the blood if there hasn't been any damage.

01:51 So if we look at the troponin results, we can indicate if there's been an injury to muscle tissue.

01:56 So that's why troponin is a cardiac bio marker.

02:00 Now have three types that are present in small amounts in your blood, troponin C, troponin T and troponin I.

02:09 So these are the proteins they're going to be an indication if they're an elevated levels that the heart has suffered damage.

02:16 So there's little difference between skeletal and cardiac muscle with troponin C.

02:21 So that one isn't used to diagnose acute coronary syndrome.

02:25 We're looking mostly at troponin T and troponin I.

02:29 Now to prone in T and troponin I are more specific for cardiac and that's their used to devaluate cardiac damage.

02:35 You'll probably particularly see troponin I predominantly but both of these will rise within three to six hours.

02:42 They'll peak at 24 to 48 hours and they'll go back to baseline over five days to 14 days.

02:49 So this is your basic to troponin I or troponin T.

02:52 This isn't the high sensitivity that we're discussing.

02:55 So troponin I and troponin T have to draw a series of tests to rule out cardiac infarction Troponins are drawn more than once and over a period of several hours.

03:06 So expect that if a patient comes in with chest pain, they're being evaluated.

03:10 We're likely going to keep them for a period of time over several hours, so the repeat lab work can be drawn.

03:17 Now if the patient has renal dysfunction, if their kidneys are kind of struggling this might interfere with the accuracy of the troponins.

03:25 Because their clearance might be decreased.

03:27 So you just keep that in mind.

03:30 Now we've come to the high sensitivity troponin test.

03:33 Now this was just approved in America for use in 2017.

03:36 So it's been around for a little bit but a relatively shorter period of time than it was been used in Europe.

03:42 So we came to the party a little late.

03:44 But now you'll see this often a high sensitivity troponin test.

03:49 It's more sensitive.

03:50 Hence the name, High sensitive troponin.

03:53 The positive results appear sooner than previous versions.

03:56 Well, that'll help us rule out an MI or identify one earlier so these are really helpful.

04:03 So if you see this you'll see it as a troponin maybe HS will indicate that it's a high sensitivity test.

04:09 So HS High sensitivity troponin may also be present in stable angina or no symptoms.

04:17 Now this may indicate an increased risk of future heart attacks.

04:21 Okay, so that's a good heads up so they can be positive even in stable angina but that doesn't mean the patient is absolutely out of heart attack, but it may indicate there's an increased risk of future heart attacks.

04:33 So that's a little bit about high sensitivity troponin.

04:37 Creatine kinase - i want to be sure that you understand that the troponin lab is more accurate, or specific, to cardiac muscle damage and is a prefered test over a CK.

04:49 Now, let me explain why myocardial cells are damaged in a heart attack.

04:54 That's why we call it myocardial infarction.

04:57 Now the cell membranes released this enzyme into the plasma within the first 30 to 60 minutes.

05:03 So That cardiac muscle is damaged, these enzymes are released in the plasma within 30 to 60 minutes.

05:10 Now CK is a measure of these enzymes or CPK.

05:15 Remember if patients had any kind of trauma like defibrillation CPR other cardiac interventions like a CABG, These will also be considered injury to the heart and you'll have these enzymes released.

05:27 So someone who's had these known events happen will also have elevated cardiac enzymes.

05:32 Now the indicate muscle damage, but it's not specific to cardiac muscle, we're talking about the CK.

05:38 So we have to do the isoenzymes.

05:41 Now those are the other two letters at the end.

05:43 CK-MM would be skeletal muscle, CK-BB is found in the brain but CK-MB is found mostly in the heart.

05:53 Now I know I keep saying this but remember troponin is going to be a more specific test.

05:58 But just in case you see these test run we want you to understand what they mean.

06:04 Now CK-MB runs means we've ordered a CPK with ISO enzymes and we're looking at the MB result if we're looking at damage to the heart because it's sensitive and specific to myocardial injury damage to heart tissue.

06:19 It rises within 4 to 8 hours peaks at about 18 to 24 and it should go back to normal within three days, If there's not ongoing heart attacks.

06:29 Now CK-MB must be greater than 5% of the total CK, in order for a definitive diagnosis of MI.

06:38 So let's look at the difference in those again CPK.

06:42 That's more global.

06:43 CK-MB is an isoenzyme.

06:46 That's most specific to cardiac.

06:49 You've got the times that you see the changes first starts to rise within four to eight hours in the test, peaks at 18 to 24 and should be back to normal in three days.

06:59 Now myoglobin might also be used with troponins, but it's not often. Used in the US.