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Discussion

any EKG reading tips?

We are learning to interpret EKG readings, and I was wondering if anyone had any tips to share. Also, if you have a way of memorzing the intervals (i.e. P wave = 0.06 - 0.12 seconds)...that would be a huge help! I do understand that depolarization = systole (P/atrium, QRS/Ventricle) and repolarization = diastole (found that explanation in the allnurse archives...) Any other suggestions other than buying a book...don't have time for that b/c test is only 10 days away...

Thanks so much!

~J

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I just finished this today. The way I remember is a regular sinus has a P wave, Atrail stuff has no P wave and QRS are normal. And Vents have no P waves or they are hidden in the T wave, QRS are widen.

Hope this helps.

Tammy

  • Expert

here you go, kiddo!

i have other links as well, but they have more advanced information. these sites are pretty basic. professor crimando's cyberheart is really nice, covers the basics, and he explains the working of the heart and ekg very well. i think you'll find more than enough information in these links to get you through a basic understanding of the electrical system of the heart and it's pathophysiology.

basically, you want to know and understand the flow of blood through the heart. you must also know how an electrical impulse is generated in heart tissue by the physiological pacemaker and the normal pathway of an electrical impulse. the normal electrical pathway is what appears as the normal sinus rhythm on a monitor strip. as parts of the heart begin to go haywire, it affects the path taken by the electrical impulses. those odd pathways are what cause the arrhythmias and the unique wave formations they create that you can see on ekg tracings. in general, the heart begins to fail in the atria and the tissues fail in a downward path. it usually takes years for this breakdown to occur to the point the patient ends up in third degree heart block and then ventricular fib/flutter as the heart is incredibly resilient and has a number of mechanisms to compensate.

http://www.gwc.maricopa.edu/class/bio201/index.htm - cyberheart from professor crimando at gateway community college in phoenix, az. ekg review and an animated heart quiz.

http://students.med.nyu.edu/erclub/ekgexpl0.html - here is a short tutorial on how to read an ekg. click on the arrows at the bottom of each page to continue through the tutorial.

http://www-medlib.med.utah.edu/kw/ecg/index.html - an excellent online tutorial with diagrams on everything you want to know about ekg interpretation from the university of utah school of medicine. also has quizzes as you move through the tutorial! geared for physicians, but nurses can get information from this also.

http://medstat.med.utah.edu/kw/pharm/ - the hyper heart - an animated tutorial of the flow of blood through the heart (click on the play button to see this animation). there are links in a drop down menu toward the left bottom of the animation page that lead you to pages explaining each one of the phases of the heartbeat.

http://scc.healthcentral.com/bcp/main.asp?ap=448&brand=24&page=ency&id=27 - this will link you to patient information on heart arrhythmia. i'm listing it because it has a list of symptoms and another list of questions to ask the doctor about heart arrhythmia. you will want to be learning the answers to some of those questions yourself as you study egks.

http://themdsite.com/ - this is the site of the dr. dale dubin who wrote rapid interpretation of ekgs. click on the link to go to the nurse's site and then scroll down to the very bottom of the page and click on "continue" to access the information for nurses. on successive pages there is always the advertising information about his book that appears first, but as you scroll down the page, you will get to the information and animations on the site.

  • Author

Daytonite!!! WOW, thanks so much! I checked out a few of these and they are great. I appreciate all this great info =)...and i'll let ya know how the test turns out. You just raised the bar for me, lol.

~J

I agree with 'Daytonite'; she gave you some great info! I worked cardiac for about 3 years and got REALLY used to reading strips and EKGs. I think the best thing was having a really good idea of what exactly the heart was doing, and what these different rhythms actually physically mean. Once I could picture in my mind the flow of blood and how the heart "looked" and reacted, it seemed much easier to figure out and remember. Good luck on your test!

Hi

Need to clarify the terms depolarisation and repolarisation, so that I can understand cardiac physiology better. So would it be acceptable to think that depolarisation mean decrease in charge to a relaxed state. As repolarisation would mean recharging so that the ventricles contract? Am I on the right track?

:wink2: :idea:

Hey SN

You've got the idea. If you want to use the ancient analogy of a rubber band as a bit of cardiac muscle, you have to stretch it first--this is POLARIZING the cells. Then you release the rubber band and SNAP!!! it DEPOLARIZES.

The reason it is important to have this picture is that the actual 'work' of the cardiac cells is done by POLARIZING themselves not by snapping. There are all these channels that the cells use to shove ions where they don't want to go. Potassium ions get pulled into the cell which is already 'full' of potassium. Sodium ions get pushed out of the cell into the interstitial area which is already full of sodium. This is when the cells burn oxygen and use glucose--during the T-Wave part of the cycle.

That is why the Pt having an MI has ST Segment changes. It's also why the ventricles have a 'refractory' period and a partial-refractory period--which is important to understanding PVCs and how V-Tach can happen.

Keep studying!! And those are really fabulous websites, Daytonite!!!

Papaw John

  • Author

LOVE the visualization/explanation pawpawjohn! =)

~J

Certain electrical events must occur in heart cells before the heart can do its work of pumping blood. Electrical activity in heart cells results when potassium, sodium, and calcium move back and forth across cell membranes. All of these electrical events can be recorded with electrodes.

Cardiac cells, in their resting state, are negatively charged inside, whereas the charge outside the cells is positive. This is called polarized. The resting cardiac cell maintains its electrical polarity by membrane pumps that ensure the proper distribution of ions (potassium, sodium, and calcium) necessary to keep the insides of these cells negatively charged. Sodium and calcium are primarily extracellular while potassium is located mostly on the cell's interior (intracelluluar).

Depolarization is the fundamental electrical event of the heart.

When a cell is stimulated (depolarized), these ions change position and there is a flow of electrical current to all cells along the pathway of conduction. Sodium rushes rapidly into the cell's interior, and calcium follows at a slower pace. Meanwhile, potassium moves to the extracellular space. This electrical activity results in contraction. Depolarization, then, occurs just before contraction.

After depolarization is complete, the cardiac cells restore their normal resting polarity through a process called repolarization. Repolarization requires more time than depolarization.

Adequate electrolyte levels (particularly sodium, potassium, and calcium) are essential for normal electrical activity to occur in heart cells.

All of the different waves that we see on the ECG are manifestations of these two processes: depolarization and repolarization.

So, to put it simply:

Depolarization

  • Positive, electrical current
  • Contraction

Repolarization

  • Returns to resting (polarized) state
  • Negative, no flow of electricity
  • Membrane pumps

Adequate electrolyte levels essential (K+, Na+, Ca++).

Just an aside: You can have electrical activity occurring without mechanical activity in a very sick heart (pulseless electrical activity). This may be caused by such conditions as tension pneumothorax, cardiac tamponade, massive MI, or severe hypovolemia. Pulseless electrical activity (PEA) is lethal and is caused by the inability of cardiac muscle to generate a sufficient force despite an electrical depolarization. In other words, the heart produces electrical activity but fails to pump.

Daytonite...you are so awsome. You always have the most helpful websites for us. Are you a nursing instructor? I was just wondering. But I wanted to say thanks...I have used many of the websites you have recommended.

you must be in my class, i have the same test, haha

  • Expert
Daytonite...you are so awsome. You always have the most helpful websites for us. Are you a nursing instructor? I was just wondering. But I wanted to say thanks...I have used many of the websites you have recommended.

Thanks! No, I'm just an old med/surg nurse who enjoys helping students out. I was treated very badly at the start of my clinical nursing career and made a silent promise to myself to try to help others from having to go through the same thing. I've often volunteered to be a preceptor. I always loved school. I am actually back in school myself studying health information management and computer use. Many of the web sites I find for students are also needed for medical coders to help them understand what they are actually putting code numbers to for billing and Medicare reporting purposes. Because of a degenerative back problem and a few other medical problems I can no longer tolerate the hours of standing and walking around in clinical areas. Before I went into nursing I studied and worked in accounting. (I love :redbeathe math.)

Daytonite & Vicky RN.....Thanks for all the info & explaining this!! :bow: I have had two cardiac lectures so far, we start ekg's & the electrical part this week. I am a little suprised because I understand it all so far.......everyone in my class is freaking out...I hope I don't join them when I get to this upcoming lecture! I had a really great A&P instructor that taught me everything we have covered so far....Please stand by for a 911 just in case! :uhoh21:

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