cardiac ekg 1
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P wave represents what?
PR interval - where is it on the EGK, what does it represent?
from start of P to R's divot
the delay of current as it runs through the AV node and Bundle of His and Purkinje fibers
QRS complex represents what?
ST segment represents what?
ventricular isoelectric period
ST interval is where on the EKG
from the the J point (the place where the the slope btwn S and T changes/flattens most dramatically) to the start of T
T wave represents what?
locations of precordial leads V1 V2 V3 V4
- V1: 4th IC R sternal border
- V2: 4th IC L sternal border
- V3: btwn V2 and V4
- V4: 5th IC in the nipple line or under the boob
locations of precordial leads V5 V6
- V5: 5th IC midaxillary line
- V6: 5th IC under armpit
in EKG the Y axis is the __
each tiny square represents __ seconds
- so a bundle of 5 is 0.2 sec
what distance on an EKG = 1 second?
5 big blocks
PR interval - how long/how many boxes?
- from start of P to R
- .12-.2 sec
- 3-5 little boxes
timing of QRS complex / boxes involved
prolonged QRS indicates...
(anything much over .1 sec) the signal is taking longer than it should to get thru the ventricle due to damage to the ventricle ... MI
timing of QT interval - seconds and boxes
- .32-.4 sec
- 8-10 little boxes
- from start of QRS to end of T
when depol is flowing toward an electrode the deflection pattern will be...
positive, and vice versa
bipolar limb lead I runs where?
R hand to L hand (+ --> -)
bipolar limb lead II runs where?
R hand to L foot (+ --> -)
bipolar limb lead III runs where?
Left hand to foot (+ --> -)
augmented leads - names and basic description
- AVR, AVL, AVF
- each is an average of the leads going toward it (maybe maybe?)
AVR doesn't give much signal bc the electricity goes L, away from it, so we sometimes don't look at that lead
precordial leads give a view in what plane?
anterior/posterior view of the heart
leads and the views they give
- Anteroseptal: V1-2
- Anterior: V1-4
- Extensive anterior: V1-6, I aVL
- Anterolateral: V3-6, I aVL
- High lateral: I, aVL
- Inferior: II, III, aVF
- Posterior: V1, V2 (ST depression, tall R waves noted)
in the QT interval (from start of QRS to end of T) what doen't you want to see?
- fixed length - that's a sign of dysrhythmia
- it should vary in length as you exercise
3 things in an ekg that should be regular
- distance from R to R
- QRS complex should look the same each time
- P wave intervals
6 second HR method
- count out 30 big squares - this equals 6 seconds
- count the R peaks in this distance
- multiply that by ten
method of finding HR that involves counting boxes between Rs
1500 divided by the number of small boxes between Rs
Dubin's method for finding HR
300 150 100 75 60 50 etc and then subdivide for the smaller boxes
first 3 things to do when looking at an EKG strip
- 1) check to see if it's regular - equal distances between R intervals?
- 2) calculate HR
- 3) check for all components of the PQRST - present? are the timings roughly right?
where in the heart is the problem if the P wave is screwed up?
what to suspect if the ST segment is low
ischemia - but you can't do more than suspect until you see another view / another EKG angle
Q wave / transmural MI -- affects EKG how?
longer QRS complex for life
what kind of drugs do folks with atrial fib require
anticoagulants to limit the clots
how fast is an AV-based rhythm?
a ventricle based rhythm?
- AV - 40-60 bpm
- ventricle 20-40 bpm - and it'll have a qider QRS
- QRS is normal
- absense of P wave
- happens when pulse is coming from AV node
basic thing you know if a p wave is present
the rhythm is originating above the AV node
normal sinus rhythm basic def
- rhythm originates from SA node
- varies from 60-99 bpm
how does sinus bradycardia look?
- < 60 bpm
- regular rhythm, P wave present, 1 p wave per QRS, timing of segments is right
clinical significance of sinus bradycardia
- can be normal in athletes
- for others, may lead to inadequate cardiac output --> tiredness, lightheadedness, syncope
sinus tacchycardia clinical significance
- diastolic period is shortened, so less time for ventricular and coronary artery filling, acna --> hypotension, angina, palpitations, or dizziness
- increased workload for heart requires more O2 consumption ... so big concern for the post MI pt
- this is >100bpm at rest, > 210 at exercise
a tachycardia originating above the ventricle -- you can call it this any time you have tachychardia with a normal looking QRS
atrial flutter simple def
a rhythm in which an ectopic atrial focus causes the atria to fire at a rate of 250-350 bpm
what does the AV node do during atrial flutter?
it blocks some of the atrial impulses, letting only every 2nd to 5th be conducted
HR with atrial flutter
- atrial rate: 250-350 bpm
- ventricular rate: 60-150 bpm depending on conduction thru AV node
regularity in an atrial flutter ekg
may be regular or irregular, depending on the conduction thru the AV node (fixed vs variable block)
how does the P wave present in an atrial flutter ekg?
- present, more than 1 btwn QRS complexes
- looks like a saw toothed pattern
- all have the same shape bc they come from one focus
clinical significance of atrial flutter
- the effect of the arrhythmia depends a lot on the ventricular response rate
- if it's fast: my compromise ventricular filling and coronary artery blood flow --> syncope, angina, CHF, PE, or hypotension
- if slow: may provide inadequate perfusion
regularity of QRS complex in an atrial flutter
they'll look the same, less that .1 sec, but they'll be varying distances apart, so the HR will seem to fluxuate a lot
atrial fibrillation description
- multiple atrial ectopic foci cause the atria to fire 300-400 bpm (in flutter it's from a single ectopic focus)
- the combo of all this firing leads to an erratic quivering of the atria w no effective atrial contractions, so no clear P waves, just a scratchy line btwn QRSes
QRS complex regularity in atrial fibrillation
it's irregular bc it's getting a shitstorm of impulses from the atria
HR in atrial fibrillation
- atrial rate is 300-400 bpm but difficult to count
- ventricular rate depends on the vent's response to the atrial ectopic foci
why should you worry if you see atrial fibrillation in a pt who hasn't had it before
pt prob isn't on anticoagulants, so the atrial fib puts the pt at risk of a stroke
regular rhythm w 1 abnormal QRS ... what should you think?
don't worry, it's only worrisome if the irregularity comes in a pattern (this is a ventricular arrhytmia)
what should you think if two PVCs come back to back? what does PVC stand for
- premature ventricular contraction
- if back to back and not same shape, this is a multifocal problem and therefore worrisome
hallmark look of a pvc
- premature ventricular contraction
- no P wave, wide QRS, inverted T
- (ventricle is contracting before it fills)
- fancy name for when every second heart beat is a PVC
- one will be pos, one neg (above/below isoelectric line)
how to determine HR in bigeminy
use the inferior QRSes bc the upper ones don't have enough filling time
if you have PVCs making up __ % or more of your QRSes per minute don't exercise
how does a first degree heart block look on an EKG?
- sinoatrial impulse is delayed longer than normal at the AV node before being transmitted to the ventricles, so...
- bigger distance than usual btwn P and QRS
clinical significance of 1st degree heart block
- usually transient
- transmission of impulse across AV node is delayed, not blocked
- if associate w an MI, the pt should be monitored for progression to higher degree AV blocks
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