EKG Analysis Flashcards
Main vector of depolarization is from?
base to apex
in to out
What does the AV node do?
delays conduction for ventricular filling; initiates impulse 40-60 bpm
Purpose of bundle of His
directs impulse to left/right bundle branches
What do the purkinje fibers do?
reaches into myocardium to stimulate ventricular depolarization
initiates impulse 20-40 bpm
When the heart depolarizes from, the myocytes go from internally ________ to internally _________.
internally negative to internally positive –> produces a positive electrical current
Standard limb leads and characteristics
Lead I, II, III
bipolar; fixed positive and negative electrodes
Limb leasd record electrical activity from right to left and top to bottom
Placement and view of Lead I
Standard limb lead
goes from neg electrode on RIGHT UPPER limb to the positive electrode on LEFT UPPER limb
corresponds to a view of the lateral wall and area supplied by the CIRCUMFLEX ARTERY
Placement and view of Lead II
standard limb lead
goes from negative electrode on RIGHT UPPER limb to positive electrode on LEFT LOWER limb
corresponds to a view of the inferior wall and the areas supplied by the RIGHT CORONARY ARTERY
Placement and view of Lead III
standard limb lead
goes from negative electrode on LEFT UPPER limb to positive electrode on LEFT LOWER limb
corresponds to a view of the inferior wall and areas supplied by the RIGHT CORONARY ARTERY
Placement and view of aVR
augmented limb lead
RIGHT ARM electrode is positive; EKG will average the distance between the LEFT ARM and the LEFT LEG and that is now the new negative pole
placement and view of aVL
augmented limb lead
LEFT ARM is positive; EKG will average the distance between RIGHT ARM and LEFT LEG and that is now the new negative pole
corresponds to a view of the lateral wall and areas supplied by the CIRCUMFLEX ARTERY
placement and view of aVF
augmented limb lead
LEFT FOOT is positive; EKG will average the distance between RIGHT ARM and LEFT ARM and that is now the new negative pole
corresponds to a view of the inferior wall and areas supplied by the RIGHT CORONARY ARTERY
Precordial leads and characteristics
V1-V6
look at events in the heart on a horizontal plane
view the anterior and lateral surfaces of the heart
positive poles are on the anterior and lateral chest and the negative poles are on the opposite side of the positive pole
V1 placement and view
4th intercostal space, right sternal border
positive electrode placed directly over RA
corresponds to the SEPTAL WALL and areas supplied by LAD
V2 placement and view
4th intercostal space, left sternal border
positive electrode placed just anterior to the AV node
corresponds to the SEPTAL WALL and areas supplied by the LAD
V3 and V4 placement and view
positive electrode placed over ventricular septum
corresponds to the ANTERIOR WALL and areas supplied by LAD
V5 and V6 placement and view
positive electrode placed over LATERAL SURFACE of LEFT VENTRICLE
corresponds to the LATERAL WALL and areas supplied by the CIRCUMFLEX ARTERY
5 lead EKG: by adding the right leg lead, what can we view?
the six limb leads (standard + augmented)
Positive deflection on EKG occurs when vector of depolarization travels ________ positive electrode.
TOWARDS A
Negative deflection on EKG occurs when vector of depolarization travels _________ a positive electrode.
AWAY FROM
Biphasic deflection on the EKG occurs when vector of depolarization travels _________ a positive electrode.
PERPENDICULAR TO
Main vector of repolarization is from?
apex to base; out to in
What does t wave inversion tell you?
Myocytes are repolarizing AROUND an area of ISCHEMIA
also during reperfusion
Criteria for RBBB
broad QRS: >120 ms/>.12 sec
RSR’ pattern in V1-V3 (rabbit ears)
Wide, slurred S wave in lateral leads (I, aVL, V5, V6)
Criteria for LBBB
ST segments and T waves
- -directed opposite to the main vector of the QRS complex
- -ST elevation and upright T waves with negative QRS complex
- -ST depression and T wave inversion with positive QRS complex
- -QRS - top hat presentation
To evaluate for axis deviation, examine which leads?
Lead I and aVF, specifically the direction of the R wave deflection
Axis deviation: vectors tend to point ______ areas that are working hard (hypertrophy) and _______ areas of injury (ischemia).
vectors point TOWARDS areas of hypertrophy
vectors point AWAY FROM from areas of ischemia.
Normal axis has a ______ R wave in both lead I and aVF.
positive R wave deflections in both lead I and aVF.
Left axis deviation: ________ R wave deflection in lead I and _______ R wave deflection in aVF.
POSITIVE R wave deflection in lead I; NEGATIVE R wave deflection in aVF.
LEAVING each other = LEFT axis deviation
Right axis deviation: ________ R wave deflection in lead I and _______ R wave deflection in aVF
NEGATIVE R wave deflection in lead I; POSITIVE R wave deflection in aVF.
REACHING for each other = RIGHT axis deviation
EXTREME right axis deviation: ________ R wave deflections in both lead I and aVF.
NEGATIVE R wave deflections in both lead I and aVF.
“thumbs down all the way around.
Causes of right axis deviation
CONDITIONS THAT MAKE THE RIGHT SIDE OF THE HEART WORK HARDER OR HYPERTROPHY
- COPD
- acute bronchospasm
- cor pulmonale
- pulmonary HTN
- pulmonary embolism
Causes of right axis deviation
CONDITIONS THAT MAKE THE RIGHT SIDE OF THE HEART WORK HARDER OR HYPERTROPHY
- COPD
- acute bronchospasm
- cor pulmonale
- pulmonary HTN
- pulmonary embolism
- mitral stenois
Normal R wave progression
looking at precordial leads: V1 - V6
“R wave progression”
smallest R wave in V1 and gets progressively larger until V4/V5
Evaluating RIGHT ventricular hypertrophy
large R wave in V1 and gets progressively smaller in V2, V3, V4
Evaluating LEFT ventricular hypertrophy
LARGE S wave in V1 and LARGER R wave in V5
–depth (in mm) of S in V1, plus the height of R in V5 if > 35 mm = LVH
LEFT axis deviation, but NO left ventricular hypertrophy = ?
ACUTE PROCESS!
LEFT axis deviation, but NO left ventricular hypertrophy = ??
ACUTE PROCESS!
T wave inversion or ST segment depression: EKG presentation + tx
ischemia
inc supply, dec demand – inc DBP, dec HR
ST segment elevation ( >1 mm): EKG presentation + tx
injury
inc supply, dec demand – inc DBP, dec HR
Infarction (old MI): EKG presentation
cellular death
Q waves are > 1 small box or 1/3 size of QRS
septal ischemia seen in which leads + associated coronary artery
V1 - V2, anterior descending artery
anterior ischemia seen in which leads + associated coronary artery
V3 - V4, anterior descending artery
anterior - septal ischemia seen in which leads + associated coronary artery
V1 - V4, anterior descending artery
inferior ischemia seen in which leads + associated coronary artery
II, III, aVF, right coronary artery/posterior interventricular branch
lateral ischemia seen in which leads + associated coronary artery
I, aVL, V5, V6, circumflex artery
