EKG II Lecture Powerpoint Flashcards
9/23
Interval definition
Segment plus a wave, a function of time
AVR lead will often write ___ complexes (pos or neg)
Neg
Y axis of an EKG is measured in ___ but is almost always commonly described in ____
mv, mm
Segment definition
Baseline between waves
PR interval function and normal interval (in sec and squares)
Measures time required for impulse to travel from SA node to ventricular myocardium, a good estimate of AV node function to slow things down, .12-.2 sec or 3 to 5 squares
P wave function and normal interval (in sec and squares and mv vertically)
Just before QRS complex representing atrial depolarization, should be <3 small squares (.12 sec) in duration and <3 squares in amplitude (.3 mv)
Tall P wave indicates….
…right atrial enlargement
PR segment function and normal interval (in sec and squares)
Follows P wave and should be flat, represents slow conduction thru av node and ends with spike in R wave, should be .12-.2 sec or 3-5 squares
Delta wave
A sign of early excitation of ventricles, indicative of re-entry such as global (wolff-parkinson-white syndrome causing tachycardia in children)
QRS complex function and normal interval (in sec and squares)
Represents ventricular depolarization, generally less than .12 sec or 3 squares
Q wave function and normal interval (in sec and squares)
1st neg deflection after the P wave, should be less than .04 sec or 1/3 amplitude of QRS complex
R wave function and normal interval (in mm vertically)
1st positive deflection of QRS complex indicative of ventricular depolarization, amplitude should be between 1-15mm
ST segment function
Represents period from end of ventricular depolarization to beginning of repolarization, should be completely horizontal except in cases of infarct or ischemia
J point
Junction between S wave and ST segment, normally at a 90 degree angle, used in a stress test as a point of measurement for st segments
T wave function and normal interval
Represents ventricular repolarization, longer than depolarization, round and positive
QT interval function
Measures QRS to end of T wave, represents ventricular depolarization to end of ventricular repolarization,
Corrected QT interval
concern when .45 sec, considered normal when less than half the RR interval
U wave
Follows T wave, not always present, same direction of deflection of the T but much smaller amplitude (often not picked up), unknown what it represents
Hyperkalemia causes ___. What are 3 other things it sometimes causes?
Increased amplitude and peaking of T wave
- prolonged PR interval
- Prolonged QRS complex
- flattened P wave
Hypokalmeia causes ___. What are 2 other things it sometimes causes?
flattened or inverted T wave
- prominent U wave
- slight depression of ST segment
Wave definition
A positive or negative tick in response to changing signal (depolarization) that forms characteristics structures of the EKG
Inverted P wave indicates…
…retrograde conduction from AV junction
1 square represents what values in mm, sec, and mv horizontal and vertically?
1mm or .04 sec horizontally, and 1mm or .1mv vertically
Widened QRS complex indicates….
…conduction delay
Significant (Q) wave
Occurs when the length is >.04 sec or one square or 1/3 the amplitude of the entire QRS complex
R wave gets progressively ___ from V1 to V4-5
Bigger
Loss of R wave progression can indicate…
…loss of left ventricular myocardial conduction (MI)
RVH causes larger R waves in V __, LVH causes it in V___
1-2, 5-6
S wave function
Caused by terminal depolarization of right ventricle in lead I, is large in V1 and larger in V2, then progressively smaller V3-6
ST segment elevation indicates…
ST segment depression indicates…
elevation indicates acute infarction and pericardidits, and depression in ischemia
T wave abnormalities
, may become inverted, peaked, or flattened due to ischemia, infarction, or medications
What lead is the T wave in verted in? What 6 is it upright in? What is it variable in?
Inverted in AVR, upright in I,II, V3-6, variable in AVL, AVF, III, V1, V2
Widened QRS complex in the right precordial leads indicates ____, widened in the left indicates ____
right bundle branch block, left bundle branch block
R waves should get progressively bigger from ____ to ___, extra large R waves in ___ indicates RVH, extra large R waves in ___ indicates LVH
V1, V5, V1-2, V5-6
S waves should get progressively ____ from V1 to V6
smaller
