EKG Flashcards
What do open sodium channels cause?
a rising phase of the action potential (depolarization)
What happens when calcium is released?
couples the depolarization wave to the myofilaments
What happens when potassium channels open?
resting membrane potential is restored (repolarization)
How does the electrical impulses travel through the heart?
SA node to AV node to AV bundle (Bundle of His) to the right and left bundle branches and end at the purkinje fibers
What does the p wave represent?
atrial depolarization
What does Q represent on the EKG?
depolarization of the ventricular septum
What does R represent?
repolarization of the distal 1/3 of the ventricular septum
What does S represent?
depolarization of the remaining ventricle
What does T represent?
repolarization of the ventricle
What does the PR interval reflect?
conduction velocity through the AV nodde
What does the QRS complex represent?
ventricular depolarization
What does the QT interval represent?
the duration of depolarization AND repolarization of the ventricle
What happens with repolarization?
the heart relaxes
What happens with depolarization?
contraction
Which ventricle contracts first?
right
How long should the PR interval last? What is happening during this interval?
.12-.20 seconds. atrial depolarization
How long should the QRS complex last? What is happening during this time?
.08-.12 seconds. Ventricles are contracting
How long should the QT interval last? What is happening during this time?
less than .5 seconds. is the duration of depolarization AND repolarization of the ventricle
What is the time elapsed between each small box on an EKG?
.04 seconds
What is the time elapsed between each bolded box on an EKG?
.2 seconds
What does a premature atrial contraction look like on an EKG?
p wave immediately following the t wave
What can a PAC indicate?
can be a sign of an irritable heart
What does a PVC look like?
may completely skip the p wave
How can you tell if PVCs are perfusing the body?
Take the pulse
What makes a sinus rhythm present?
a p-wave
What does the AV node start?
ventricular contraction (depolarization)
What is it called when a p wave is not present (i.e. sinus rhythm is not present)?
Junctional
What is it called if the junctional rhythm is between 60 and 100 bpm?
accelerated
If a junctional rhythm is over 100 bpm?
junctional tachycardia
What would a wave be called if the t and the p wave become indistinguishable?
supraventricular
What would a patient feel like if they are experiencing SVT?
restless, anxious, they would be pale and have low perfusion, Tachypnic, and hypotensive
What does an atrial flutter look like on an EKG?
“saw tooth” waves
How many atrial depolarizations reach the ventricles if a patient is experiencing atrial flutter?
about one in three
How quick does the atrium typically fire at if someone experiencing atrial flutter?
250-350 bpm
What happens when there is atrial fibrillation?
rapid continuous firing of multiple atrial foci
What is someone at higher risk for if atrial fibrillation occurs?
stroke and pulmonary emboli
How are the impulses firing on the atria during Afib?
like fireworks across the entire atrium
Is Afib a regular rate?
no. it is always irregular
What would a patient typically be given if they are experiencing A-fib with rapid ventricular response?
ditalizem or amiodarone as well as heparin or lovenox
What happens when a patient is experiencing Afib with ventricular response?
Blood is clotting in the atria and immediately getting sent out to the body
What happens during VTach?
only the ventricles are beating
What should be done if VTach is present without a pulse?
CPR
How many PVCs need to be present to indicate Vtach?
3 or more consecutively at a rate greater than 100 bpm
What happens in a first degree AV block?
prolonged PR interval
What happens in a second degree AV block?
Wenckebach (progressive block of the AV node) or Mobitz (Blocks the purkinje fibers)
What happens in a 3rd degree AV block?
complete AV block
What happens with a Wenckenbach?
p wave takes longer, longer, longer to show up and then it drops completely
What happens in a Mobitz block?
a number of P waves occur before a successful QRS (2:1, 3:1, or higher)
What happens in a complete block of the AV node?
prevents sinus paced atrial depolarization from reaching ventricles and the p wave is independent of the QRS rate
What happens on an EKG when there is a bundle branch block?
widened QRS interval
What is the difference on an EKG between Afib and V-Fib?
Afib will still have a QRS complex
Where is a transvenous pacemaker placed?
pulmonary artery
Where do the wires of a permanent pacemaker rest?
endocardium
