The Blocks

Objectives Identify the four types of atrioventricular blocks Differentiate EKG strips showing the types of blocks List causes of each block Describe treatments for each block. Objectives At the end of this presentation, you should be able to: Identify the four types of atrioventricular blocks Differentiate EKG strips showing the types of blocks List causes of each block Describe treatments for each block.

Atrioventricular (AV) block Can you do something like this: http://www.washingtonhra.com/16.html Atrioventricular (AV) block is a delay or interruption in the transmission of an impulse from the atria to the ventricles due to an anatomic or functional impairment in the conduction system. The conduction disturbance can be transient or permanent.

Interpreting blocks First degree Second degree type I Second degree type II Third degree Insert image of EKG strip or something similar (the one below isn’t positioned or sized quite right) Blocks can be time consuming to interpret. You have to know more than just the too fast, too slow or not at all interpretation. There are 4 blocks to contend with. They are: first degree, second degree type I, second degree type II, and third degree.

First degree Most common Elongated PR interval Appears normal, no missing QRS EKG strips are from http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cardio&part=A548 First degree. This is the most common of the blocks. In this dysrhythmia the PR interval is elongated. There is no missing QRS or anything else, the rhythm looks normal until you carefully look at the PR interval. This is sometime seen in young athletes and in patients without history of cardiac issues.

Second degree, type I Also known as Wenckebach Causes: AV node ischemia PR interval elongates until QRS complex is dropped Increased vagal tone Digitalis therapy Usually transient 2nd degree Type I: AKA Wenckebach. In this block the PR interval becomes longer and longer until a QRS complex is dropped. This may be caused by AV node ischemia, increased vagal tone, or digitalis therapy. This is usually transient and the patient will often revert back to normal rhythm without outside intervention.

Second degree, type II Also known as Mobitz type II. More serious than type I No progression QRS complex usually wider than normal Can progress to 3rd degree block 2nd degree type II: AKA Mobitz type II. This is more serious than Type I because there is no progression to the loss of the QRS complex, no rhyme or reason. This can represent a complete block of one of the bundle branches and the QRS complex is usually wider than normal. Each of the blocks can progress to a more complicated or serious heart block. Left alone this can progress to 3rd degree block.

Third degree Also known as a complete heart block Atria and ventricles not communicating Slow ventricular rate Considered lethal 3rd degree: AKA Complete Heart Block. The most serious of the blocks because the atria and the ventricles are not communicating with each other, they are literally independent entities. The ventricular rate is usually not sufficient and slow. This is considered to be a lethal arrhythmia because it can progress to asystole without intervention.

Conclusion