USMLE Forums banner

Action potential duration and the QT interval

4134 Views 1 Reply 2 Participants Last post by  donofitaly
please help me get these:rolleyes:
i need to know ;

1-what factors determine QT interval? how come sometimes medications which widen QRS do not change QT interval? is not QRS complex a part of QT?

2-all class1 antiarrytmics block sodium channels at phase 0,then should not we expect all class1s widen QRS? then why i just read class1a and 1c,but not 1B widen qrs?and again we have long QT with class1A but not with 1c,how come?

3-again about QRS, how come we have widen qrs in ventricular tachycardias??? i mean how ventricel could contract fast if it spends more time during depolarization?

2-is QT same as action potential duration(APD)?

:eek:i do not feel good to ask these very basic q about heart physiology that i was supposed to know well before ,,yearsssss back, but i have to understand it sometime , better now!

thankss for any inputs
  • Like
Reactions: 2
1 - 1 of 2 Posts
1 - 1 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.