Cardiac Enzymes… The Little Red Flags

Have you heard of the term “Cardiac Enzymes” and thought: enzymes – GI – heart – WTF? That’s ok. In a nutshell, when heart muscle is damaged a series of markers are released which we can pick up in a blood draw. This is vital information, because as you may know, people are weird… I’ll rephrase that, people present differently, some completely asymptomatic, hence the weirdness.

It's a chest pain kinda day for my pts #thattroponindoe #hollaatdemenzymes pic.twitter.com/XRwt5kEPj9

— xJaeJx, RN, BSN (@xJaeJxRNx) January 9, 2014

So this is a tweet I posted from a while back, look at that troponin, the normal values for my facility are right there so you can see how off the scale it is! This dude was in trouble.

So there are the TROPONINS – the most specific cardiac marker and the release times are quite prolonged, but you can use this guide to help you determine what you are dealing with:

So what about the other indicators? Well look at this graph to see the time they are released. Although Troponins are cardiac specific, this does not mean we discount the others, its all evidence of cardiac breakdown.

MB band of Creatine Kinase (CK-MB). An “enzyme” marker for myocardial infarction, the MB band of CK-MB is indicative of injury in many muscles, but its release is a highly specific indicator for MI. It is only elevated for 48-72 hours afterwards, though, making it less useful than troponin I for diagnostic purposes.

Cardiac Tamponade

This has nothing to do with tampons in the heart ok! Just an FYI.

When blood or fluid accumulate in the sac which surrounds the heart it exerts pressure against the heart, making it harder for the heart to pump. As you can imagine, if the ventricles cannot fill fully or contract effectively then cardiac output decreases. Decrease cardiac output is not good news!

So how do you know if someone has this?

Well the symptoms are nothing unusual: chest pain, restlessness, quick shallow breathing, palpitations, pallor, tachycardia, weak peripheral pulses, pulsus paradoxical, distended neck veins, low BP… (do these all sound a little familiar? MI anyone?) Well causes of cardiac tamponade can be MI, Dissecting aortic aneurysm (thoracic), end-stage lung cancer, heart surgery, Pericarditis caused by bacterial or viral infections, or direct wounds to the heart.

How do we diagnose? Echocardiogram is the usual diagnostic tool, but MRI, CT, CXR or EKG can also highlight or confirm this.

Can you see the halo of fluid around the heart?

This is an emergency! The fluid must be drained to reduce damage to the myocardium and reestablish cardiac output.

Pericardiocentesis is a procedure that uses a needle to remove fluid from the pericardial sac, the tissue that surrounds the heart. The patient will be hyperoxygenated, given fluids to maintain blood pressure. It is important to note that a pericardiocentesis may have to be repeated because cardiac tamponade can return. With fast treatment the outcome is usual good, without treatment death is immanent.

A pericardial draining tube may be placed during surgery to keep in place postop. The drainage will be measured every shift and documentation on the color, amount and consistency is very important! The tube will usually be removed slowly over the postop recovery weeks at the discretion of the cardiologist.

Great Little Story to Remember Those AV Heart Blocks!

❤The Sad Story of a Struggling Marriage…❤

1st Degree AVB
Husband comes home late every night at the same time, but he
ALWAYS comes home!!!

** P waves aren’t on time but always present! Prolonged PRI

2nd Degree AVB Type 1 (Mobitz 1 or Wenckebach)
Husband comes home later and later and later until one night he
doesn’t come home at all, then the pattern starts all over again!!!

**P wave “Going, going, gone”, PRI gets longer & longer till P is dropped

2nd Degree AVB Type 2 (Mobitz 2)
Husband comes at the same time every night, but there are some
nights that he just doesn’t come home!!!

**P wave is on time but randomly drops

3rd Degree AVB (Complete)
Husband and wife are finally divorced but can’t afford to move out of
their house because of the bad economy. As a result, they are still
living under the same roof, but leading two separate lives!!! It
appears as if they’re still married, but they’re not! There is no
communication between them!!!

** P waves, PRI are not in sync with Ventricular activity (QRS) and its a hot mess!

EKG Time!

EKG TIME! (For basic understanding)

Ok so for many the EKG is a weird and wonderful map of squiggles, but actually each little squiggle is very important in translating the conduction of the heart. From your A&P course you should know that the normal conduction of the heart starts in the SA node in the Right Atrium, it travels to the AV node in the wall of the right atrium (middle of the heart), then through the Bundle of His/Left & Right Bundle Branches and down through the Purkinje fibers. The EKG is basically a map of that scenario. Imagine that you are in a car in San Antonio (SA node), you need to drive to Aventura (AV node), then you go through the spaghetti junction (Bundle of His) while heading to Pittsburg (Purkinje fibers) – if you were to use Google maps, you would have the route highlighted out on the roads you have to take, right? Well that is basically what an EKG is! It is the highlighted route the conduction took through the heart.

I hope that has given you a little clarity on those squiggly lines, haha!

Now what does the map tell us?

As you can see we use letters to signify different areas of the squiggle. You can see that P is a little bump at the beginning. This is showing us that the atria of the heart are depolarizing (another fancy word for compress or pump). The atria is pushing the blood into the ventricles. P shows that the car has left the SA node in the Right Atrium and is traveling to the AV node in the middle of the heart. From P to Q (called PR complex),  the car then leaves the AV node and travels down through the Bundle of His. One the car travels out from the Bundle of His down the Bundle Branches, through the Purkinje fibers and the rest of the heart so a QRS complex occurs. The QRS shows that the ventricles have received all the blood from the atria and pumps it back out to lungs (right V) and aorta (left V). And with that you have just witnessed a heartbeat.

Well what about the leftover squiggles…

So between the S and the T (called the ST segment), we see the heart recovering from the heartbeat, otherwise known as Ventricular REpolarization. Think about clenching your fist really hard and then relaxing, that is in essence what the heart is doing. The ST segment is very important to monitor on an EKG strip because if you are looking for something pathological, such as an MI, you might just find it here with ST segment elevation. This would mean the patient would be diagnosed as having a STEMI. We could continue this further, but we’ll save the pathological changes for another time.

So following the T wave, the heart is now ready to complete another beat! We have come full circle!

I hope you found this helpful, it is purely for basic understanding, EKG’s can be much more in depth! My best advice is so search YouTube for videos, as visualizing this is the best way to learn what it going on inside the heart!

Good Resources:

http://www.youtube.com/watch?v=7b98JcGIGyE

http://handwrittentutorials.com/

Rapid Interpretation of EKG’s 6th Ed. – Dale Durbin (really good book)