Med-Surg - Cardiovascular System, part 6: Dysrhythmias
by Cathy Parkes September 29, 2021 Updated: April 24, 2022 9 min read
In this article, we'll cover basics on the dysrhythmias you need to know about in med-surg. We won't go into any details about EKG interpretation; if you need to learn EKG interpretation for these dysrhythmias, you can check out our EKG Interpretation - Nursing Flashcards.
The Med-Surg Nursing video series follows along with our Medical-Surgical Nursing Flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.
Sinus tachycardia is a regular cardiac rhythm wherein the heart rate is greater than 100 BPM.
The causes of sinus tachycardia can include physical activity, anxiety, fever, pain, anemia, medications, or as compensation for decreased cardiac output or blood pressure.
The recommended treatment for sinus tachycardia is to treat the underlying cause. For example, for sinus tachycardia due to a fever, the goal would be to treat the fever!
Sinus bradycardia is a regular cardiac rhythm wherein the heart rate is less than 60 BPM.
Sinus bradycardia can be brought on by excess vagal nerve stimulation, cardiovascular disease, cardiovascular infection, hypoxia, or certain medications. Sinus bradycardia is a normal or expected finding in athletes (because their heart might be working very efficiently and does not need to beat as often).
Sinus arrhythmia is a normal variant from a normal sinus rhythm where the heart rate increases slightly with inspiration (breathing in) and decreases slightly with expiration (breathing out).
Sinus arrhythmia causes
Sinus arrhythmia is common in children and typically disappears with increased age.
Sinus arrhythmia treatment
Treatment for sinus arrhythmia is usually not necessary.
Atrial dysrhythmias include atrial fibrillation, atrial flutter, premature atrial complexes, and supraventricular tachycardia.
Atrial dysrhythmia risk factors
Atrial Fibrillation (AFIB)
Atrial fibrillation (AFIB) is rapid and disorganized depolarization of the atria in the heart which causes the atria to quiver or “fibrillate” instead of fully squeezing. This causes blood to collect in the atria, which places a patient at HIGH risk for clots.
Atrial flutter is when an abnormal electrical circuit forms in the atria of the heart, causing it to depolarize 250 - 350 times per minute.
Atrial flutter treatment
The treatment for atrial flutter is cardioversion and/or antiarrhythmics.
Premature Atrial Complexes (PAC)
Premature atrial complexes (PACs) are premature discharges of the electrical signal in the atria of the heart.
Treatment of PACs is not usually necessary. What can help reduce PACs is decreasing stress, and avoiding alcohol and caffeine.
Supraventricular Tachycardia (SVT)
Abnormally fast HR that originates above (supra = above) the ventricles, typically in the atria.
The treatment for SVT is usually cardioversion and antiarrhythmics.
Ventricular dysrhythmias include premature ventricular complexes, ventricular tachycardia, ventricular fibrillation, and asystole.
Ventricular dysrhythmia risk factors
The risk factors for ventricular dysrhythmia risk factors include heart disease, a myocardial infarction (heart attack), and electrolyte imbalances.
Premature Ventricular Complexes (PVCs)
A premature ventricular complex (PVC) is an abnormal impulse that originates from the ventricle and occurs early.
The treatment for PVCs include antiarrhythmics, when the PVCs are symptomatic.
Ventricular Tachycardia (VT/V-tach)
Ventricular tachycardia is a rapid ventricular heart rhythm greater than 100 beats per min, usually due to ischemic heart disease. VT can often deteriorate into ventricular fibrillation (explained next).
The treatment for ventricular tachycardia when the patient has a pulse is cardioversion, antiarrhythmics, and correcting electrolyte imbalances.
The treatment for ventricular tachycardia when the patient does not have a pulse is defibrillation (Clear!).
Ventricular Fibrillation (VF/V-fib)
Ventricular fibrillation is rapid, ineffective quivering of the ventricles in the heart.
Ventricular fibrillation is an emergency so the treatment is defibrillation!
Asystole is the absence of any ventricular rhythm. The EKG of asystole is basically a flat line, which is where the term "flatlining" comes from. Usually, asystole happens after V-tach or V-fib has deteriorated.
The treatment for a patient in asystole is immediate CPR. Asystole is a "non-shockable rhythm" so defibrillation would not be done.
Atrioventricular (AV Block)
Atrioventricular (AV) blocks are some dysrhythmias you should know about, and there are two types: first-degree AV block and second-degree AV block.
AV block risk factors
First-Degree AV Block
A first-degree AV block is a prolonged impulse conduction time from the atria to the ventricles in the heart due to a delay in the AV node. First-degree AV block usually does not require treatment, but may progress into a more severe block.
Second-Degree Type 1 AV Block
A second-degree type 1 AV block is marked by a progressive increase in impulse conduction time between the atria and ventricles until one impulse finally fails to conduct at all. Second-degree type 1 AV block is usually temporary and does not require treatment.
Second-Degree Type 2 AV Block
A second-degree type 2 AV block is marked by a sudden failure of impulse conduction from the atria to the ventricles, without a progressive increase in conduction time.
Second-degree type 2 AV block usually requires a pacemaker.
Third-Degree AV Block
Third-degree AV block is a complete failure of any and all impulse conduction from the atria to the ventricles. A third-degree AV block requires a pacemaker for the patient.
I am Cathy with Level Up RN. In this video, I am going to cover cardiac dysrhythmias, and at the end of the video, I'm going to give you guys a little quiz to test your knowledge of some of the key facts I'll be covering in this video. So definitely stay tuned for that. If you have our medical-surgical nursing flashcards, definitely pull those out so you can follow along with me.
So in this video, I will not be covering how to interpret EKGs. We actually have a whole separate flashcard deck and video playlist for that. So if you need help with interpretation of EKGs, definitely head on over there to get help. Here, we're just going to go over some basic facts about dysrhythmias and the treatment of those dysrhythmias.
First up, let's talk about sinus dysrhythmias, which includes sinus tachycardia.
With sinus tachycardia, we have a regular cardiac rhythm, but our heart rate is over 100 beats per minute.
Causes include physical activity, anxiety, fever, pain, anemia. It can also be caused by your body, compensating for decreased blood pressure or decreased cardiac output.
Treatment is focused on treating the underlying cause. So, for example, if your patient has sinus tachycardia due to unresolved pain when we give them pain medication that often allows that heart rate to come down.
Then we have sinus bradycardia. This is where we have a regular cardiac rhythm, but our heart rate is under 60 beats per minute.
Causes include excess vagal stimulation, cardiovascular disease, hypoxia, as well as certain medications. It's also important to note that with athletes, they often have sinus bradycardia, and this is a normal and expected finding in athletes. So I'm not saying I'm an athlete, but I do work out a lot and my resting heart rate is around 50 beats per minute.
In terms of treatment, if the patient is symptomatic, if they have a shortness of breath and fatigue associated with their bradycardia, we can give them atropine as well as a pacemaker. But for asymptomatic bradycardia, treatment is often not required.
And finally, we have sinus arrhythmia. So this is a normal variant from normal sinus rhythm. This is where the heart rate increases slightly with inspiration and decreases slightly with expiration.
It's common in children, and it usually disappears with age, and treatment is not necessary for sinus arrhythmia.
Next up, we have our atrial dysrhythmias, and I won't go through all the information on the card, but I do want to highlight atrial fibrillation as well as atrial flutter.
So with atrial fibrillation or AFib, we have a rapid and disorganized depolarization of the atria, such that the atria will sit there and quiver instead of fully squeezing. And as it sits there and quivers, blood collects in there, and we have increased risk for blood clot formation.
So a key intervention for a patient who has AFib is to put them on an anticoagulant in order to prevent that clot from occurring.
Also, we can treat this condition with cardioversion, which we'll talk about more in my next video as well as antiarrhythmics. So when you look at an EKG strip, AFib will look like lots of little bumps between the QRS complexes.
All right, with atrial flutter, we have an abnormal electrical circuit that forms in the atria and causes rapid depolarization of the atria. So between 250 and 350 times per minute.
So when you look at an EKG strip and you see these sawtooth waves, so these are F waves, that's atrial flutter, and we would also treat this with antiarrhythmics as well as cardioversion.
Next, let's talk about some key ventricular dysrhythmias, including ventricular tachycardia or V-tach.
With V-tach, we have a rapid ventricular rhythm. So over 100 beats per minute on an EKG strip. You will not see any P waves. You will see wide QRS complexes that occur regularly.
V-tach is typically caused by ischemic heart disease.
Treatment of V-tach with a pulse includes cardioversion, as well as antiarrhythmics and correction of any electrolyte imbalances. If we have V-tach without a pulse, we need to defibrillate. V-tach can deteriorate into ventricular fibrillation or V-fib.
With V-fib we have rapid, ineffective, quivering of the ventricles. So on an EKG strip, you're not going to see any P waves and you're really not going to be able to see any QRS complexes. It's just going to be all these little bumps going across the screen.
Treatment of ventricular fibrillation is defibrillation.
So our little chicken hint here is to D-fib, V-fib.
And then finally, we have asystole, which is where there is absence of any ventricular rhythm. So on an EKG strip, this will look like a line. So this is something you never want to see in your patient, but you always want to see on a test because it's really easy to identify that dysrhythmia.
So treatment of asystole includes CPR. So despite what you may have seen on some kind of medical TV show where they attempt defibrillation on a patient with asystole, you cannot do that in real life. So you need to perform CPR on a patient who has asystole.
Finally, let's talk about some AV blocks or atrial ventricular blocks, which are typically caused by heart disease, by myocardial infarction. They can also be caused by certain medications, such as beta-blockers or the digoxin.
With a first-degree AV block, we have a prolonged impulse conduction time between the atria to the ventricles due to a delay in the AV node. So on a EKG strip, you will see a long PR interval that is consistent.
Treatment is typically not required for this type of heart block.
Then we have a second-degree type one AB block, which is where we have a progressive increase in the conduction time between the atria and the ventricles until one impulse fails to conduct at all. So on an EKG strip, we will see a PR interval that will gradually get bigger and bigger until a QRS complex drops.
Treatment is also not typically needed for this type of block, either.
Then we have a second-degree type two AV block. This is where we have a sudden failure of impulse conduction between the atria and the ventricles without a progressive increase in conduction time. So on your EKG strip, you will see a consistent PR interval. It'll either be consistently long or consistently normal, but then suddenly you'll just have a QRS complex that drops off.
This type of block typically requires a pacemaker.
And then finally, we have a third-degree AV block. This is where we have complete failure of any conduction between the atria and ventricles. So when you look at an EKG strip, you will see no association between the P waves and the QRS complexes.
Treatment of this type of block does require a pacemaker.
Okay, time for a quiz. I have three questions for you.
First question, what dysrhythmia is associated with an increased risk for clots?
The answer is atrial fibrillation. And that's why anyone who has AFib is put on an anticoagulant to help prevent that clot formation.
Question number two, what is the treatment for ventricular tachycardia without a pulse?
The answer is defibrillation.
Question number three, what is the treatment for ventricular fibrillation?
The answer is defibrillation, again. So we want to D-fib, V-fib.
All right, I hope this video has been helpful for you, and I hope you enjoyed this quiz. If so, be sure to leave me a comment. I would love to hear from you, and I'll see you on another video soon.
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