ECG - Conduction Problems

1st Degree Heart Block

* PR interval is prolonged, ~ 360ms  (normal PR interval is 120 - 200ms or 3 - 5 small squares)

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Causes of 1st degree heart block include: 

  1. Coronary artery disease
  2. Acute rheumatic carditis
  3. Digoxin toxicity
  4. Electrolyte disturbances

2nd Degree Heart Block

* Mobitz Type II —> PR interval remains constant, however one P wave is not followed by QRS complex

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* Wenckebach / Mobitz Type I —> Progressive lengthening of PR interval, followed by one P wave not conducted, next conducted beat has shorter PR interval

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* 2:1 / 3:1 —> 2 P waves followed by QRS complex or 3 P waves followed by QRS complex

P waves can be in the T waves as well.

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 (2:1)

Causes of 2nd Degree Heart Block are the same as 1st Degree Heart Block

3rd Degree Heart Block / Complete heart block

- Atrial contraction is normal, however, none of the beats are conducted to the ventricles

- Could be due to fibrosis of the Bundle of His from previous myocardial infarction, or can occur during an acute myocardial infarction

** No relationship between P waves and QRS complexes. QRS complexes may be abnormally shaped as well due to the inconsistent spread of impulses in the ventricles. 

** the easiest way to see this is to draw a line to mark every P wave - make sure that the interval between each P wave is similar and constant, then see how the QRS complexes are not related to the P wave.

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Right Bundle Branch Block

* has not much significance, may be a normal variant

* best seen in V1 as an M pattern - RSR1 / however in V6 there will be a flip - W pattern seen

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Left Bundle Branch Block

* Best seen in V6 - M pattern, likewise at V1 it will be seen as a W pattern

* Causes: Aortic stenosis, ischemic disease

* When patient complains of chest pain (symptomatic), it could indicate an acute myocardial infarction

**** Left axis deviation + Right bundle branch block = SEVERE conducting tissue disease, may require pacemaker ****

source: The ECG made easy, Hampton JR, 2008

anonymous said:

sometimes my heart does this weird thing where it starts beating super fast for no reason. It comes without warning, no emotions involved, and it's so fast that I feel like it's going to rise to my throat and choke me. And then as suddenly as it begins, it stops.

Hello there, Bringing Winky Back

Um, yeah, so you didn’t actually come out and ask me “Is this a bad thing?”, but I figured you probably weren’t just telling a perfect stranger about your “wacky cardiac events” in order to make conversation.

So, in case you were wondering: your heart isn’t supposed to do that. You should see a doctor about it; they will probably have you get cardio-diagnostic testing, which could include:

  • EKG and rhythm strip (but if your heart is beating in normal rhythm at the time, these might not be very helpful).
  • Wearing a “Holter” monitor for a period of time to try to record the precise heart rhythm (or lack of one) which occurs when your heart suddenly starts shuckin’ and jivin’
  • Echocardiogram (heart ultrasound)
  • Evaluation of secondary causes for heart rhythm disturbances (lab work to check electrolytes, thyroid, and hemoglobin status, among others).

If it tends to do this for a long enough period (more than 15-20 minutes), perhaps you could arrange with your doctor to come in to their clinic “as soon as it acts up,” so that perhaps they can “catch” the rhythm irregularity on an EKG.

Good luck!

Watch on cuddlepuddlez.tumblr.com

Because I’m a total nerd and my professor showed this video in class today when we were talking about AV Blocks.

Watch on maggiscool.tumblr.com

Second-Degree AV Block aka Type I, Mobitz I or Wenkckebach

That’s right. Canadians (^_^)v

1) Use lead II

2) Note the progressive increase in length of PRI on the ECG

The SA node isn’t the problem. It’s the AV node. Therefore, the P wave WILL be conducted and mapped on the ECG BUT it will not consistently be followed by the QRS complex after because the sinus impulses does not always reach the ventricles.

Anyway! Awesome video.

Watch on logiclost.tumblr.com

When the Beat drops…
#EKG #ECG #nursing #nursingproblems #nursingschool #nurse #wenckebach

Watch on thirty-what.tumblr.com

Diagnosis Wenckebach

So funny, if you’re medical…

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