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91 Cards in this Set
- Front
- Back
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EKG smallest box =
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0.04 seconds
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EKG big box =
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0.2 seconds
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P wave represents ...
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atrial depolarization
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normal p wave width
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no more than 0.11 seconds wide
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PR segment represents ...
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the delay in AV node
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PR interval represents ...
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atrial depolarization plus delay in AV node
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normal PR interval length
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0.12 - 0.20 seconds
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Q wave
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first negative wave after the P wave, before the R wave
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S wave
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the negative wave after the R wave
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QRS complex represents...
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represents ventricular depolarization
may have one, two or all three (QRS) |
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normal QRS interval
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0.06 to 0.11 seconds
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ST segment represents...
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represents time during which the ventricles have depolarized completely and the beginning of repolarization
(QRS to beginning of T wave) |
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Normal ST segment
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isoelectric at baseline
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J point
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The angle at which the QRS ends and the ST segment begins
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T wave represents...
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represents ventricular repolarization
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normal T wave
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may be positive or negative
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U wave represents ....
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repolarization of Purkinje fibers
small wave after the T wave, often not seen |
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QT interval represents ...
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time of ventricular depolarization and repolarization
measured from first wave of QRS to end of T wave |
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Normal QT interval
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based on HR
The slower the HR, the longer the QT IF HR 60 -100 bpm, the QT is < 1/2 the R to R |
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What is the "pacemaker rule"?
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The fastest rate will control the heart
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What is an "escape" rhythm?
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When an upper pacemaker fails (i.e. SA node) its up to a lower pacemaker (junctional, ventricular) to take over....this is an escape
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Serum K < 3 mEq EKG changes:
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Flat T wave, prominent U wave
ST segment flattening/depression |
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Serum K < 2 mEq EKG changes
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U wave taller than T wave
Prolonged QT interval ST segment depression |
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Serum K < 1 mEq EKG changes:
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U wave fuses with T wave
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Serum K > 5.5 mEq EKG changes
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Tall, narrow peaked T waves
QRS widens P wave widens and becomes shallow |
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Serum K > 6.5 mEq EKG changes
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QRS complex widens more
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Serum K > 8 mEq EKG changes
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Wide QRS merged with T wave
p wave barely visible |
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Serum K > 12 mEq EKG changes
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p wave disappears
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Hypocalcemia EKG changes
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Prolonged QT interval
Prolonged ST segment |
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Hypercalcemia EKG changes
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Shortened QT interval
SHortened ST segment |
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Hypomagnesemia EKG changes
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Prolonged QT interval
Broad, flattened T wave |
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Hypermagnesemia EKG changes
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PR interval & QT interval prolonged
Prolonged QRS complex |
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Digitalis effect on EKG
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scooping of ST-T wave
shortened QT interval PR interval may be prolonged |
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What are the 6 limb leads?
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I, II, III, aVR, aVL, aVF
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What are the 6 chest leads?
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V1-6
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Name locations of the 6 chest leads
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V1= 4th intercostal, R. sternal border
V2= 4th intercostl, L sternal border V3 = 1/2 between V2 and V4 V4= 5th intercostal, L midclavicular line V5= 5th intercostal, L anterior axillary line V6= 5th intercostal, L midaxillary line |
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The R wave gets _____ across the precordium from V1 to V6
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taller
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Conditions associated with poor R wave progression across precordium (3)
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AMI
L BBB emphysema |
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sinus block (sinus exit block)
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missed beat in sinus rhythm but R-R interval at block (missed beat) measures exact multiple of normal regular R-R interval
aka-just a missed beat but rhythm stays regular |
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Sinus arrest
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missed beat (can be more than 1)
R-R interval at pause is different than normal R-R interval |
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wandering atrial pacemaker
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P waves look different beat to beat, at least 3 different looking P waves
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supraventricular tachycardia rate
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> 100 bpm, usually 150-250 bpm
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atrial flutter (rate & regularity)
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regular
a rate 300 bpm V rate varies with conduction (i.e. 2:1, 4:1) |
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atrial fibrillation (rate & regularity)
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irregular
a rate 350 bpm V rate depends on conduction through AV node |
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Junctional escape rhythm rate
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40 - 60 bpm
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accelerated jxnl rhythm rate
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60-100 bpm
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Can jxnl rhythm have p waves?
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yes. May be inverted.
May be in front of or in the QRS complex |
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junctional tachycardia rate
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> 100 bpm, usually 100 -180 bpm
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1st degree AV block
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PR > 0.20 seconds
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Mobitz I (Wenckebach) 2nd degree AV block
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longer longer longer drop
now you got a Wenckebach (p wave but no QRS eventually, repeat) |
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Mobitz II 2nd degree AV block
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randomly dropped beats
(p wave but not QRS, randomly) |
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Third degree AV block
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atria and ventricles are doing their own thing
A & V rhythms are both regular |
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L BBB QRS is...
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> 0.12 seconds
Negative in V1 |
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R BBB QRS is...
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> 0.12 seconds
Positive in V1 |
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monomorphic VT rate
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100-250 bpm
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polymorphic VT rate
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150-250 bpm
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Idioventricular rhythm rate & describe
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20-40 bpm
no atrial activity QRS > 0.12 sec |
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Accelerated idioventricular rhythm rate & describe
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40-100 bpm
no atrial activity QRS > 0.12 seconds |
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What does the mean QRS axis represent?
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the average direction of ventricular depolarization
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which direction is the normal QRS axis?
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downward and to the left (0- 90 degrees)
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Left axis deviation (direction)
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upward and the left (0 to -90 degrees)
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causes of L. axis deviation (5)
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only abnormal if > -30 degrees
LV hypertrophy L anterior hemiblock septal/inferior MI V pacemaker mechanical shift of heart (ascites, pregnancy, tumor) |
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Right axis deviation (direction)
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downward and the right (+90 to +180 degrees)
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causes of right axis deviation (5)
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normal if only up to +110 degrees
RV hypertrophy pulmonary embolism L posterior hemiblock lateral MI dextrocardia (congenital, heart in R side body) |
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What is indeterminate axis deviation?
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when axis deviation is -90 to +/- 180
"no mans land" |
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causes of indeterminate axis deviation (5)
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V tach
ventricular pacing multiple MI's hyperkalemia severe RV hypertrophy |
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What is the quadrant method for determining axis deviation?
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The direction of the QRS in leads I (through L arm) and aVF (down through foot) is used to determine axis
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In lead one if the mean QRS axis is left/right then the QRS deflection will be ___/____
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positive/negative
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In lead aVF, if the mean QRS axis is upward/downward, then
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negative/positive
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If QRS is positive/negative in lead I/aVF, then the axis deviation is...
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lead I + aVF + = normal
lead I + aVF - = left axis deviation lead I - aVF - = indeterminate axis lead I - aVF + = right axis deviation |
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RV hypertrophy EKG changes
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Right axis deviation (lead I - aVF +)
QRS= R wave larger than S wave in V1 and V2, S wave larger than R wave in V5 & V6 |
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LV hypertrophy EKG changes
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Left axis deviation (lead I + aVF -)
Deepest S wave V1&V2, tallest R wave V5, V6 |
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The earliest EKG changes in an MI are...
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T wave changes (tombstone T waves/T wave inversion)
T wave inversion is in leads facing the ischemic area |
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MI injury EKG changes...
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ST segment changes
elevation in leads facing the area |
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MI infarction is shown in what EKG changes
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Q wave changes
pathologic Q waves in leads facing necrotic area |
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Are Q waves ever normal? When are they not normal?
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Yes they can be. IF they are 0.4 seconds wide or 1/4 height R wave they are pathologic
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How long do Q waves take to develop?
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up to 24 hrs
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anterior MI leads
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V2,3,4
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septal MI leads
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V1,2
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anteroseptal MI leads
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V1,2,3,4
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lateral MI leads
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I, aVL (high lateral), V5,6 (low lateral)
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anterolateral MI leads
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V3,4,5,6 (I, aVL)
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inferior MI leads
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II, III, aVF
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posterior MI leads
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V7,8,9 or reciprocal in V1,2,3
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Which coronary artery is anterior, septal MI?
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LAD
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Which coronary artery is lateral MI?
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LCA
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Which coronary artery is Inferior MI?
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RCA
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Which coronary artery is posterior MI?
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RCA and/or LCA
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Can ST segment elevation be present immediately (hyperacute phase MI?)
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yes
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EKG changes in pericarditis
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ST segment normal in V1 and aVR
all other leads show ST elevation |
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What ST changes are considered significant?
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ST elevation/depression of at least 1 mm (small box) for at least 60 seconds
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