Cardio- Airey (EKG) Flashcards
upward vs downward deflection on EKG
An upward deflection is from electrical activity coming toward a positive electrode
A negative deflection is from electrical activity going away from a positive electrode
P wave
depol of atria (repol not seen)
PR interval
time from initial atria depol to initial depol of ventricles
QRS complex (what are the upward wave(s) )?
depol of ventricle
two upward waves? - R and R’
T wave
repol of ventricle
QT interval
first ventricle depol to final repol
lead I , lead II, lead III
Lead I: RA (-) to LA (+) (Right Left, or lateral)
Lead II: RA (-) to LL (+) (Superior Inferior)
Lead III: LA (-) to LL (+) (Superior Inferior)
V1 location
4th intercostal space, R sternal border
V2 location
4th intercostal space, L sternal border
V3 location
between V2 and V4
V5 location
horizontally even w/ V4, but in anterior axillary line (more lateral)
V6 location
even w/ V4 and V5 but in midaxillary line (more lateral)
place a total of ___ electrodes to get a ___ EKG. where are these placed?
10 electrodes for 12 lead EKG
4 on extremities:Anywhere as long as 10cm from heart [One of theses is a ground lead- prevents AC interference- ignore it, usually right leg]
6 electrodes are placed across the chest
where are the 12 leads from
6: extremities (I, II, III, AVR, AVL, AVF)
6: chest (V1-V6)
what do the letters in AVR, AVL, AVF mean?
A: augmented V: voltage R: right arm L: left arm F: left foot
which leads are over the interventricular septum?
V3 and V4
what part of the heart are you looking at ? leads I, II, III?
I- lateral
II and III: inferior
what part of the heart are you looking at? leads AVR, AVL and AVF?
AVR: none
AVL:lateral
AVF: inferior
what part of the heart are you looking at? V1-V6?
V1 and V2: septal
V3 and V4: anterior
V5 and V6: lateral
elongated PR interval?
heart block in AV node (normal is 0.12 -0.2 seconds) >0.2 is 1st degree AV block
elongated QRS?
electricity if spreading through the system slowly or abnormally (normal is <0.12 seconds)
how big are the small blocks on EKG? what about the bolded lines?
1mm, 5mm
how much time does each block represent on the EKG graph paper?
Single square 0.04 sec, 0.20 seconds between 2 heavy lines
what would sinus tachy or sinus brady be?
Sinus bradycardia- a rate less than 60 beats per minute
Sinus tachycardia- sinus rate more than 100 beats per minute
Rate: automaticity foci in atrial foci, AV junction and ventricles?
Atrial foci= 60-80/min
AV Junction= 40-60/min
Ventricles= 20-40/min
arrhythmia of sinus origin
usual conduction pathway, but either too fast, too slow or irregular
ectopic arrhythmia
rhythms starting at a place OTHER than the SA node
reentry arhythmia
elec. activity is going on in circles instead of forward through the normal pathway
conduction blocks
starts normal at SA node but has a block or delay
preexcitation syndrome
type of arhytmia : elec. activity follow alternate pathway allowing for shortcut through the system.
Pwave : QRS complex should be ….
one to one
hypertrophy (enlarged chamber) can cause what 3 things (seen on the EKG) ?
- increase the duration of the depolarization: EKG wave will be wider
- generate more electrical energy: EKG wave will have greater amplitude
- A larger percentage of TOTAL electrical current will move through the chamber which will change the average of the main vector (QRS Axis)
what is the QRS axis? how is it measured ?
The direction in which most of the electricity is traveling through the ventricles
Measured as a circle superimposed on the chest and given in degrees
abnormal QRS axis…
With certain abnormalities the QRS axis will point in the wrong direction. E.g. if one ventricles wall is thicker than other, more electricity is running through QRS orientation changes from normal
normal axis vs axis deviation
Normal: 0 to +90
Right axis deviation (RAD): +90 to 180
Left axis deviation (LAD): 0 to -90
Extreme axis deviation: -90 to 180
right axis deviation
Negative in I & positive in AVF
Happens in children, tall adult, pulmonary embolism, chronic lung disease
left axis deviation
I positive and AVF negative Look at lead II as a tiebreaker Positive normal Negative-left axis deviation With left ventricular hypertrophy and inferior MI
elongated QT interval?
> 0.44 seconds, signals an arrhythmia
1st, 2nd and 3rd degree AV blocks
AV blocks slow or eliminate the conduction from the atria to the ventricles
1st degree: Lengthens the delay between atrial and ventricular depolarization (PR >0.2seconds)
2nd degree: Some get through , some don’t
3rd degree: Completely blocks conduction of atrial stimulation to ventricles
sinus block
skip a cycle (flat line on graph then back to normal)
block in the AV node vs block in the bundle of His/purkinje system
AV node: wenkelbach: progressive lengthening of PR interval until QRS drops,
bundl system: mobitz : normal cycle followed by series w.out QRS
3rd degree block
P waves made but not passed through ventricle
BBB (bundle branch blocks) - right vs left shown on EKG
The resulting QRS is a combination of the two ventricles depolarizing and so has “two” R waves. R and R’ (R-prime) in a RBBB and a widened, notched QRS in a LBBB.
what leads do you look at for BBB?
chest leads: 1 and 2 are right, 5 and 6 are left
how would atrial enlargement be seen?
See in P wave, best in V1
Two ways:
P wave above and below baseline, biphasic
P wave > 2.5 boxes= right atria enlarged
where would ventricular enlargement be seen?
QRS complex in chest leads
infarction vs ischemia
Infarction- heart muscle is dead
Ischemia-heart muscle not getting enough blood
where on the EKG can infarction/ischemia be seen?
T waves (if inverted)
ST segments: look if its above (infarction) or below (ischemia) baseline and for sloping
Q waves: > One small square wide or 1/3 of QRS amplitude. think MI > 7 days old
If isolated T, ST, or Q changes (just in one lead) or in leads that are not in adjacent area of heart then the changes might not be due to _____ could be wrong _____
MI or ischemia, could be wrong lead placement
what is WPW: wolf-parkinson-white syndrome) ?
Extra bundle of tissue (accessory) in AV conduction pathway
Depolarization can go through here faster
Called pre-excitation
Gives a Delta wave on QRS
Looks like a short PR
what are you at risk for with WPW?
SVT (surpraventricular tachy) w/ rapid conduction