QRS and Axis Flashcards
how should the QRS look in leads AVF, II, III
mostly positive deflections; vectors coming toward these leads
how should the QRS look in lead AVR
mostly negative; stimulus traveling away
how should the QRS look in lead I and AVL
q wave is normal. mostly positive deflection because stimulus travels away
in the precordial leads V1 is mostly
negative deflection
as you move across the chest in the precordial leads from right to left the QRS deflection becomes
increasingly positive
what is the criteria for low voltage
<10mm in the precordial leads
an example of a situation that would have low voltage
pericardial effusion
an example of a situation with high amplitude/height of the QRS
hypertrophy
what is a normal QRS duration
< 0.12 seconds
name some causes of a wide QRS
hyperkalemia**: not as fast as vtach <125 bpm BBB idioventricular rhythms VPCs vtach WPW abberancy meds (tricyclics) pacemaker IVCD
how would you know a wide QRS is from a pacemaker
pacer spikes lines
what does multifocal PVCs look like
multiple PVCs in the same lead of different shape; coming from different foci in the ventricle
a QRS notch at the end of the complex ( j point)
benign, common in precordial leads
if you saw a QRS notch with a benign ST segment elevation what should you consider
pericarditis
early repolarization
what is an osborn wave
a large hump right after the QRS complex that is NOT the t wave
what condition does an osborn wave signify
hypothermia
in what conditions is a q wave considered benign/insignificant
- small q waves in leads AVL and I
- QS in V1 ONLY
- isolated q wave in lead III only
- Q wave in AVR
what classifies as a pathologic Q wave
height > 1/2 height of the R wave
width > or equal to 0.04 seconds or 1 small box
True or false: 1 lead in a region that has a q wave is concerning
false; 1+ leads in a region is where you get concerned for pathologic q waves
if you saw a q wave in leads V1, V2, V3 with no upward notching what is this
pathologic- MI
where is the normal transition zone of the precordial leads
between V3 and V4
what classifies as an early transition
before V3
what classifies as a late transition
after V4
what is the normal QT interval measured from
the beginning of the QRS complex until the end of the t wave
what is the normal duration of the QT interval
< 1/2 RR interval
a prolonged QT interval can lead to…
torasades de point
what can the ventricular axis help you diagnose
hemiblock- definitively R/L hypertrophy PE dextrocardia lead misplacement
what is the normal axis
0-90 degres
what is LAD
left axis deviation -1 to -90 degrees
what is RAD
right axis deviation 91 to 180 degree
if QRS is + in lead I, and + in AVF what is the axis
NORMAL
if QRS is + in lead I and - and AVF
LAD
if QRS is - in lead I and + in AVF
RAD
calculating normal axis:
if lead I > lead AVF what is the axis in degrees
0-40 degrees
calculating normal axis:
if lead I < AVF what is the axis in degrees
40-90 degrees
calculating normal axis:
if lead I = lead AVF
45 degrees
calculating normal axis
if lead I is isoelectric
90 degrees
calculating normal axis
if lead AVF is isoelectric
0 degrees
causes of left axis deviation
normal variant with aging
left anterior hemiblock
causes of right axis deviation
normal variant in kids/teens right ventricle hypertrophy left posterior hemlock dextrocardia pulm pathology
at what degree is LAD considered pathologic
greater than 30 degrees
< 30 is normal variant with aging
if you have LAD and you look to lead II and see an isoelectric QRS deflection what degree could you assume
-30 degrees; borderline pathologic
if you have an LAD and you look to lead II and see a negative deflection you know that the degree is
> -30 degrees; pathologic
where is a left anterior hemiblock located
left anterior fasicle
where is a left posterior hemiblock located
left posterior fasicle
which is more common, LAH or LPH
LAH
T or F: diagnosis with an EKG is definitive for LAH
true
T/F: diagnosis with an EKG is definitive for LPH
false; dx of exclusion
how does a LAH present
LAD: lead I is + lead AVF is -
lead II is negative
what is a bifasicular block
RBBB + LAH/LPH
RBBB + LPH ok or bad
BAD; concern for complete heart block and anterior MI
RBBB + LAH
ok, common fin dinging
only not ok if ischemic
