Step I Rx QID 1019

[dyspareunia]

Can anyone explain how you know that Mobitz type-II is more commonly associated with His-Purkinje defect than AV block?

 

[notbobtrustme]

it helps to see the question and answer choices 🙂

 

[Ionian]

Can anyone explain how you know that Mobitz type-II is more commonly associated with His-Purkinje defect than AV block?

Because we learned it in class, so I know its true.

Plus it's not hard to reason out, AV node is the site with the highest delay, if there is a defect there you an expect the PR interval to lengthen.

Since Mobitz type-II involves random drops of QRS complexes not proceeded by changes in the PR interval you can assume there is no problem making it through the AV node, only a problem with the final conduction to the ventricles. Hence, His-Purkinje defect.

Im pretty sure it was explained better either in FA, or Rx though.

 

[dyspareunia]

it helps to see the question and answer choices 🙂

Not sure how much detail I can post without violating some rule, but the question was very short.. Not much other info than below.

75 year old man gets a pacemaker to treat his heart block. His ekg shows constant PR with QRS appearing randomly.

What's the abnormality?

AV abnormality
His-purkinje
Independent contraction of atria and ventricles
Retrograde ckndjction
SA abnormality

Because we learned it in class, so I know its true.

Plus it's not hard to reason out, AV node is the site with the highest delay, if there is a defect there you an expect the PR interval to lengthen.

Since Mobitz type-II involves random drops of QRS complexes not proceeded by changes in the PR interval you can assume there is no problem making it through the AV node, only a problem with the final conduction to the ventricles. Hence, His-Purkinje defect.

Im pretty sure it was explained better either in FA, or Rx though.

There's no explanation in FA or RX other than "his-purkinje is most commonly responsible for mobitz 2"

What you say makes sense though.