B. blockers supress abnormal pacemakers by decreasing slope of phase 4 - USMLE Forums
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Old 06-27-2013
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Drug B. blockers supress abnormal pacemakers by decreasing slope of phase 4

Hi,
I am wondering what is meant by this sentence in FA
"B. blockers supress abnormal pacemakers by decreasing slope of phase 4"
Any help is appreciated!
Thanks
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Old 06-27-2013
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I think it means that beta blockers (class II antiarrythmics) will decrease phase 4 which is the spontaneous depolarization phase that is characteristic of pacemaker cells. In case the heart is having abnormal pacemaker cells, instead of the SA node, the beta blockers will help decrease this depolarization and help the SA node take over those abnormal cells that are firing.

That is also why these class II antiarrythmics can lead to heart block.
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