PNB 2265 Lecture Notes - Lecture 9: Ventricular Fibrillation, Atrial Fibrillation, Atrioventricular Node

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Clinical Uses of EKG
Normally, pretty evenly spaced out
Bradycardia: still see all the waves,
everything is still there but less frequency
o More spread out
Tachycardia: fast heart rate, more
o Stress and exercise
o Still very coordinated, QRS are still
evenly spaced apart
AV block: no coordination of contractility
(no/reduced QRS)
o Not functioning
o Travel to atria, hit AV
node, severe delay/no conduction (instead of small delay)
o A lot of P wave: atrial depolarization
o QRS and T barely present
Maybe QRS a little bit because still have atrial repolarization
Purkinje fibers can still generate AP
Long QT syndrome
o Slow recovery from contraction may lead to VFIB
o Within T wave
o Time for ventricles to repolarize is slower
P-Q interval: time between atrial depolarization and ventricular depolarization
o AP is going to AV node
T wave is ventricular repolarization
Mediated by potassium channel influx
Fibrillation: NOT tachycardia what’s different?
o Atrial fibrillation: uncoordinated contraction of atria and ventricles
No P wave: EKG has uncoordinated electrical activity
Even uncoordinated in atria, nothing wrong with AV, so pockets of
depolarization send signal to ventricles, still see QRS (relatively normal)
QRS: not evenly spaced, still uncoordinated
Not the same as tachycardia because tachycardia is evenly spaced
Treatable with medication
Atria contracting is not essential for filling ventricles
o Ventricular fibrillation: heart cannot pump
Ventricles are larger
Even if atria are still coordinated, still not pumping blood
Synchronize coordination by shocking them
V Fib needs help ASAP
Myocardial Infarction
Hyperacute T-wave: pointy
o Earliest sign of MI
o Heart beginning to become ischemic
o Hyperkalemia (why?)
o K ions are flooding out of cell
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