Advanced ECG Flashcards
cardiac conduction pathway 10
1 sa node 2 anterior internodal fascicle 3 middle internodal fasicle (wenckebach bundle) 4 posterior internodal fascicle (thorels pathway) 5 bachman bundle 6 av node 7 bundle of his 8 RBB 9 LBB 10 Purkinje fibers
phase 4 non pacer action potential electrical conduction cells
resting membrane potential -90
phase 0 non pacer action potential electrical conduction cells
depolarization
na moves intracellular
phase 1 non pacer action potential electrical conduction cells
start repolarization
K moves extracellular
phase 2 non pacer action potential electrical conduction cells
plateau phase
Ca moves intracellular
phase 3 non pacer action potential electrical conduction cells
finishes repolarization
Ca channel close
SA node action potential phase 4
spontaneous repolarization
Na and Ca constantly in
SA node action potential phase 0
slow depolarization
Ca in
SA node action potential phase 3
repolarization ca channel open k open (out)
5 large boxes =
1 second
1 large box =
0.2 seconds
what action potential has the fastest repolarization?
SA node
limb leads
I, II, III, aVR, aVL, aVF
standard/bipolar limb leads
I, II, III
which lead has a negative electrode on the R arm
1
2
which lead has a negative elctrode on the L arm
3
augmented/unipolar limb leads
aVR, aVL, aVF
in what orientation do the limb leads examine the heart through
frontal plane
bipolar limb leads
positive and negative electrodes
current moves from neg to pos
Lead I
180 to 0
right arm to left arm
Lead II
-120 to 60
right arm to left leg
Lead III
-60 to 120
left arm to left leg
augmented unipolar leads
obtained by modifying the bipolar limb leads
ONLY have positive electrode
naming unipolar limb leads “a” stand for
augmented or modified
naming unipolar limb leads “v” stands for
vector
vector can point to positive electrode on left or right or foot
naming unipolar limb leads “R,L,F” stands for’?
where the postive electrode is
example: aVR - postitive electrode is in right arm
Lead aVR created?
modified lead III
left arm and left leg cancel out to create positive electrode going towards right arm
aVR degrees
30 to -150
Lead aVL created?
modified lead II
right arm and left leg cancel out and create positive electrode going to left arm
aVL degrees
150 to -30
lead aVF created?
modification of lead I
right arm and left arm cancel out and create positive electrode going to foot
aVF degrees
-90 to 90
mean electrical axis
main cardiac vector
sum of all of the MANY vectors of electricity that the heart makes
what leads does the mean electrical axis apply to?
only limb leads
normal QRS axis (MEA)
-30 to 110
left axis deviation
cardiac vector falls within -30 to -90 range
possible causes of left axis deviation
LVH
inferior wall MI
right axis deviation
90 to 180
possible causes of right axis deviation
RVH
young age (children have larger RV)
dextrocardia
extreme right axis deviation
-90 to -180
if the MEA vector travels the same direction as the lead youre using how will that effect the R wave
positive R wave deflection
(upright QRS)
if the MEA vector travels the opposite direction as the lead youre using how will that effect the R wave
negative R wave deflection
(inverted R wave)
if the MEA vector travels perpendicular to the lead youre using how will that effect the R wave
equiphasic deflection of the r wave
if a pt has a normal QRS axis then the R wave will be ______ in lead aVR
negative (inverted)
if a pt has a normal QRS axis then the R wave will be ______ in lead II
positive (upright)
if a pt has a normal QRS axis then the R wave will USUALLY be ____ in lead I
upright
if a pt has a left axis deviation then the R wave will be _____ in lead I
positive (upright)
if a pt has a left axis deviation then the R wave will be ____ in leads II,III, aVF
negative (inverted)
if a pt has a left axis deviation then the R wave will be ______ in leads aVL
upright
if a pt has a right axis deviation then the R wave will be ____ in leads III, AVF
positive (upright)
if a pt has a right axis deviation then the R wave will be _____ in leads I, aVL
negative (inverted)
suppose the MEA is 140, the QRS will be _____ in lead 2
upright
suppose the MEA is 140, the QRS will be _____ in aVL
inverted
suppose the MEA is -60, the QRS will be _____ in lead 1
upright
suppose the MEA is -60, the QRS will be ____ in aVF
inverted
suppose the MEA is 90, the QRS will be _____ in lead 1
biphasic
suppose the MEA is 90, the QRS will be ______ in aVL
upright
main criteria to diagnose left axis deviation
negative R deflection in lead II
main criteria to diagnose Right axis deviation
negative R deflection in lead I
precordial leads
V1-V6
what plane to the precordial leads examine the heart in?
horizontal (transverse)
Right precordial leads
v1, v2
2nd intercostal space
left precordial leads
v3-v6
steps to analyze an ECG 6
1 Rate? 2 Rhythm? 3 P waves? 4 QRS Complexes? 5 All intervals? 6 Signs of Ischemia?
SSS
tachy brady syndrome
malfunctioning SA node
ectopic atrial beat
beat that originates from the atrial myocardium
different p wave morphology
ectopic atrial tachycardia
bunch of ectopic atrial beats rate >100
wandering atrial pacemaker
ectopic beats that are originating from multiple sites in atria
ECG description of wandering atrial pacemaker
irregularly irregular with p waves
3 or more different p morphologies
HR <100
MAT or CAT
mutlifocal atrial tachycardia or chaotic atrial tachycardia
ECG description of MAT
irregularly irregular rhythm with p waves
multiple p wave morphologies at least 3
HR >100
how is MAT treated?
antiarrhythmics
cardioversion is NOT effective
type 1 atrial flutter
atrial Rate <350
type 2 atrial flutter
atrial rate >350
afib with rapid ventricular response (RVR)
hr >100
controlled afib
ventricular rate <100
uncontrolled afib
ventricular rate >100
normal junctional rhythm
40-60bpm
accelerated junctional rhythm
60-100 bpm
junctional tachycardia
> 100bpm
SVT
> 150 bpm
bigeminy
every other beat
trigeminy
every third beat
unifocal
same shape (originate from the same place)
multifocal
different shape (originate from different places)
couplet
2 in a row
salvo
3 or more in a row
mobitz 2 degree av block type 1
p-r interval gradually gets larger then drops beat
mobitz 2 degree av block type 2
long p-r interval and dropped beat
right bundle branch block
impulse from bundle of his will only go down LBB and the RV depolarizes by myocardium
ECG description RBBB
two r waves (rSR) in V1/V2
slurred S waves (ST depression) in V5/V6
broad, slurred S waves (ST depression) in V5/V6
first R wave in RBBB
from left ventricle depolarization
second R wave in RBBB
right ventricle depolarization
intrinsicoid deflection
time from beginning of QRS to the peak of QRS
which patients have delayed intrinsicoid deflection
BBB
LBBB
impulse from bundle of his will go down right bundle branch and then the left will depolarize through the myocardium
first R wave in LBBB
right ventricle depolarization
second R wave in LBBB
left ventricle depolarization
ECG description for LBBB
RSR (double r wave) in:
I, aVL, V5-V6
can see deep S wave in V1/V2
St depression and or Twave inversion in I, aVL, V5/6
symptoms of BBB
usually asymptomatic
treatment for symptomatic BBB
cardiac resynchronization with biventricular pacemaker
aberrancy
abnormal conduction in the R or L bundle branches
which bundle branch has longer refractory period
RBB refractory is longer than LBB
what can SVT with aberrancy present like
VTACH
right atrial enlargement
also known as right atrial abnormality and has TALL P WAVES
ECG criteria for RAE
one or more:
tall p waves(>2.5mm) in I, II, III
tall p waves (>1.5mm) in V1/2
what is RAE a result of?
pulmonary HTN
pulmonic stenosis
tricuspid stenosis/regurg
left atrial enlargement
known as left atrial abnormality
ECG criteria for left atrial enlargement
one or both
wide P wave in limb leads >120msec
negative or biphasic p wave in V1/V2 (>1mm in depth and width)
what is LAE a result of?
aortic stenosis/regurg
mitral stenosis/regurg
ECG criteria right ventricular hypertrophy
tall r waves V1
deep s waves in V5/6
R(V1)+S(inV5or6)= >10.5mm
ECG criteria left ventricular hypertrophy
deep s wave V1
Tall R waves V5/6
S(V1)+R (V5or6) >35mm
LVH with repolarization abnormalities
repolarization abnormalities or strain when it is accompanied by st depression or t wave inversion
r wave progression
increase in the magnitude of the r wave from v1 to V4/5
this is normal
poor r wave progression
often seen after myocardial infarction and suggests myocardial defects
electrical alternans
alternation of QRS complex amplitude between beats
possible causes of electrical alternans
cardiac tamponade
pericardial effusion
acute MI
heart wobbles in pericardial sac
signs of coronary ischemia 4
1 st depression or elevation in 2 or more contiguous leads
2 pathologic Q waves
3 inverted or missing t wave
4 electrical alternans
pathologic Q waves
> 40msec wide
1/3 height of QRS
what is the most sensitive lead for measuring st segment changes?
V5
treatment of ischemia/infarction
increase O2 supply to pt
decrease O2 demand
obtain cardiology consult
coronary blood supply 5 main
aorta right coronary artery left coronary artery circumflex coronary artery left main coronary artery
what does the right coronary artery supply blood to? 5
SA node AV node inferior wall posterior wall inferior 1/3 ventricular septum
what does the left anterior descending LAD supply blood to?
anterior left ventricle
ventricular septum
ventricular septum
what does the circumflex artery supply blood to?
posterior left ventricle
lateral left venticle
lateral left ventricle
contiguous leads
leads that are a group of ECG leads that repressent the same area of the heart that receives similar blood supply
inferior wall ecg leads and blood supply
II,III, aVF
RCA
right coronary artery
lateral wall ecg leads and blood supply
I, aVL, V5, V6
CFlex
circumflex artery
septum ecg leads and blood supply
V1, V2
LAD
left anterior descending artery
anterior wall ecg leads and blood supply
V3 V4
LAD
left anterior descending artery
anteior MI cause by what
block of Left coronary artery
how is anterior Mi diagnosed?
ischemia in leads V3-4
inferior MI caused by what
block of the right coronary artery
inferior MI diagnosed?
ischemia in leads II,III, aVF
lateral MI caused by what?
block of the circumflex artery
lateral MI diagnosed?
ischemia in leads I, aVL, V5, V6
which lead is the most sensitive for detecting lateral wall ischemia
V5
posterior MI caused by what?
block of the circumflex and right coronary arteries
posterior MI diagnosed?
ischemia in V1-V3
septal MI caused by?
block of the left anterior descending
septal MI diagnosed?
ischemia in V1-V2
ecg artifact
make ecg uninterpretable
monitor filter mode
filters out electrical iterference
low frequency filter
eliminates baseline drift associated with patient movement
high frequency filter
reduces electrical noise
ecg artifact related to st segments
accuracy of st segment readings on intraoperative ecg monitors are affected if filters are used
