14 EKG Basics
![](https://photos.thisispiggy.com/file/wikiFiles/dbJ9ah8.jpg)
- SA to LA and RA myocytes
- HIS bundles, left and right BBB, purkinje embedded in myocytes
![](https://photos.thisispiggy.com/file/wikiFiles/U4kkMqw.jpg)
- time x axis, electrical activity in y axis
- P: atrial depolarization
- flat after P: time for electrical activity to go to ventricles
- QRS: ventricle depolarize
- T: repolarization of ventricle. Atrial repolarization happens during QRS
Pacemaker and Hr
![](https://photos.thisispiggy.com/file/wikiFiles/KCUSLrr.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/1JUdAwB.jpg)
- speed by which electricity moves through heart
![](https://photos.thisispiggy.com/file/wikiFiles/QQz9REJ.jpg)
- most of time between P and QRS is by AV nodal conduction
![](https://photos.thisispiggy.com/file/wikiFiles/y0Ynsbj.jpg)
- small box: 40 ms
- big box: 200 ms
- 300 / # of big boxes
EKG lead
![](https://photos.thisispiggy.com/file/wikiFiles/YrfvXDG.jpg)
- some electrical activity to left, right
- sum of all activity: arrow
- each of 12 EKG leads look at summation from different POV = different QRS shape
![](https://photos.thisispiggy.com/file/wikiFiles/2H8WDJe.jpg)
- AVR: summation away, negative QRS
- 1, AVL: summation towards, positive
![](https://photos.thisispiggy.com/file/wikiFiles/id2vfzQ.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/dp1l7gZ.jpg)
QRS Axis
![](https://photos.thisispiggy.com/file/wikiFiles/YIm4CKj.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/r2rS5Vb.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/9cWoCsa.jpg)
- -30 and -90
- V tach, activity not from SA node but from ventricle itself
![](https://photos.thisispiggy.com/file/wikiFiles/dVUSEQn.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/41RfJna.jpg)
- positive lead 1: toward 0
- negative lead 1: towards 180
- positive lead 2: going down
- negative lead 2: going up
- added lead 1 and 2 vectors to have summation vector
![](https://photos.thisispiggy.com/file/wikiFiles/55m5Bjx.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/sR0zNmY.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/DlSKqBT.jpg)
- exception: part up part down, physiologic, slightly to left, nl
![](https://photos.thisispiggy.com/file/wikiFiles/Lo1wAmN.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/svt1cRP.jpg)
Intervals
![](https://photos.thisispiggy.com/file/wikiFiles/TYwpKCV.jpg)
- PR: shorter than 1 big box
![](https://photos.thisispiggy.com/file/wikiFiles/iLtjrqw.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/Q2GCXrM.jpg)
- Inactivated peanut butter jar: TCAs block the cardiac fast Na+ channels, decreased contractility, QRS, QT propagation
- Wide QRS crack: TCAs can widen the QRS complex on ECG
- Twisted torsades streamer: TCAs can induce torsades
![](https://photos.thisispiggy.com/file/wikiFiles/C2KRST6.jpg)
- Lightly held peanut butter jar: class IA antiarrhythmics have an intermediate binding affinity for the Na+ channel (intermediate use-dependence, moderate slowing of the phase 0 upstroke)
- Pushing away the curtain: class IA antiarrhythmics also block K+ channels, prolonging phase 2 and 3 of the cardiac action potential -> prolonged refractory period
- Twisted torsades streamer: class IA antiarrhythmics can cause Q-T interval prolongation (precipitates torsades) (K channel prolongation)
- Wide QRS shaped crack: class I antiarrhythmics widen the QRS complex on the ECG (decreased AP conduction velocity) (faster cells bind more and slow down more) (QRS widen as HR increases)
![](https://photos.thisispiggy.com/file/wikiFiles/CPprsGV.jpg)
- less than half QRS - QRS
- left: T begin immediately without flat portion
![](https://photos.thisispiggy.com/file/wikiFiles/AXpFMyM.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/3ZcnD89.jpg)
- hypocalcemia: less driving force to move Ca in, longer for Ca to go in, longer for QT interval to occur (myocyte in ventricles to depolarize, repolarize )
![](https://photos.thisispiggy.com/file/wikiFiles/yJ61jY3.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/6VwAAW7.jpg)
- Torsades strip: risk of prolonged Q-T interval
![](https://photos.thisispiggy.com/file/wikiFiles/x1Lu2Gg.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/z0iaNLl.jpg)
- Twisted streamer: FGAs can cause torsades de pointes
![](https://photos.thisispiggy.com/file/wikiFiles/C2KRST6.jpg)
- Lightly held peanut butter jar: class IA antiarrhythmics have an intermediate binding affinity for the Na+ channel (intermediate use-dependence, moderate slowing of the phase 0 upstroke)
- Pushing away the curtain: class IA antiarrhythmics also block K+ channels, prolonging phase 2 and 3 of the cardiac action potential -> prolonged refractory period
- Twisted torsades streamer: class IA antiarrhythmics can cause Q-T interval prolongation (precipitates torsades) (K channel prolongation)
- Wide QRS shaped crack: class I antiarrhythmics widen the QRS complex on the ECG (decreased AP conduction velocity) (faster cells bind more and slow down more) (QRS widen as HR increases)
![](https://photos.thisispiggy.com/file/wikiFiles/gRuqWDx.jpg)
- Pushing away the curtain: class III antiarrhythmics block K+ channels prolonging phase 2 and 3 of the cardiac action potential -> prolonged refractory period
- Twisted streamer: sotalol, dofetilide, and ibutilide can induce torsades (although all type III antiarrhythmics can widen the QT interval)
![](https://photos.thisispiggy.com/file/wikiFiles/Q2GCXrM.jpg)
- Inactivated peanut butter jar: TCAs block the cardiac fast Na+ channels, decreased contractility, QRS, QT propagation
- Wide QRS crack: TCAs can widen the QRS complex on ECG
- Twisted torsades streamer: TCAs can induce torsades
![](https://photos.thisispiggy.com/file/wikiFiles/AZRcoE9.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/6VwAAW7.jpg)
- Torsades strip: risk of prolonged Q-T interval
![](https://photos.thisispiggy.com/file/wikiFiles/x1Lu2Gg.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/z0iaNLl.jpg)
- Twisted streamer: FGAs can cause torsades de pointes
![](https://photos.thisispiggy.com/file/wikiFiles/C2KRST6.jpg)
- Lightly held peanut butter jar: class IA antiarrhythmics have an intermediate binding affinity for the Na+ channel (intermediate use-dependence, moderate slowing of the phase 0 upstroke)
- Pushing away the curtain: class IA antiarrhythmics also block K+ channels, prolonging phase 2 and 3 of the cardiac action potential -> prolonged refractory period
- Twisted torsades streamer: class IA antiarrhythmics can cause Q-T interval prolongation (precipitates torsades) (K channel prolongation)
![](https://photos.thisispiggy.com/file/wikiFiles/gRuqWDx.jpg)
- Pushing away the curtain: class III antiarrhythmics block K+ channels prolonging phase 2 and 3 of the cardiac action potential -> prolonged refractory period
- Twisted streamer: sotalol, dofetilide, and ibutilide can induce torsades (although all type III antiarrhythmics can widen the QT interval)
![](https://photos.thisispiggy.com/file/wikiFiles/Q2GCXrM.jpg)
- Inactivated peanut butter jar: TCAs block the cardiac fast Na+ channels, decreased contractility, QRS, QT propagation
- Wide QRS crack: TCAs can widen the QRS complex on ECG
- Twisted torsades streamer: TCAs can induce torsades
![](https://photos.thisispiggy.com/file/wikiFiles/4KRKPwF.jpg)
- longer to depolarize/repolarize, longer QT
![](https://photos.thisispiggy.com/file/wikiFiles/a80eNX2.jpg)
- not really seizures, passing out from torsades
![](https://photos.thisispiggy.com/file/wikiFiles/9DiJwr7.jpg)
- hyperacute: precede ST elevation in ischemia
![](https://photos.thisispiggy.com/file/wikiFiles/rAMN9Xs.jpg)
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