Unit 4 - EKGs Flashcards
what are EKGs compromised of?
vector sums
what are EKGs assessed for?
rate, rhythm, axis, and injury
what is rate calculated by?
counting number of large boxes (200 ms) from R-R
-300-150-100-75-60-50-37.5
what is normal:
- PR interval
- QRS
- QT
- PRI: 0.12 - 0.20 sec
- QRS: 0.06 - 0.10 sec
- QT: 0.36 - 0.44 sec
what is bradycardia, normal, and tachycardia?
brady < 50
normal = 50 - 100
tachy > 100
what is expected in normal sinus rhythem?
- every QRS is preceded by a P-wave
- 1:1 concordance between P-waves and QRS
- PR interval is constant or approximately constant
what leads are used to measure axis?
I and aVF
- both upright: normal
- I upright, aVF downward: left axis
- I downward, aVF upward: right axis
- both downright: extreme right axis
what does ST depression VS elevation mean (usually)?
depression: myocardial injury
elevation: myocardial infarction
what are inferior wall leads?
II, III, aVF
what are lateral wall leads?
I, aVL, V4-6
what are anterior wall leads?
V2-4
what are septum leads?
V1-2
what are posterior wall leads?
(depression in) anterior-septal leads (V1-4)
what does atrial tachycardia show?
preserved rhythm, but abnormal rate
what does atrial fibrillation show?
rapidly occurring abnormal waves replacing normal P wave
what does atrial flutter show?
saw-toothed waves replacing P wave
-ventricular depolarization occurs after several atrial waves
what does atrioventricular block show?
PR interval gradually prolonged until QRS complex completely disappears
what does premature ventriclar contraction show?
occurs at random, disrupting normal rhythm (downward wave)
what does ventricular tachycardia show?
rapidly widened QRS complexes of irregular shape
what does ventricular fibrillation show?
fibrillatory waves are small and irregular, or large and bizzarely shaped
what are the bipolar leads? where do they go?
I - left arm to right arm (lateral)
II - left leg to right arm (inferior)
III - left leg to left arm (inferior)
what are the unipolar leads? where do they go?
aVL - left arm to indifferent electrode (right arm + right leg) = lateral
aVR - right arm to indifferent electrode (left arm and left leg) = lateral
aVF - left leg to indifferent electrode (left arm and right arm) = inferior
what are the precordial chest leads? where do they go?
V1 - right sternal margin, 4th intercostal space (anterior/septal)
V2 - left sternal margin, 4th intercostal space (anterior/septal)
V3 - halfway between V2 and V4 (anterior)
V4 - 5th intercostal space in left mid-clavicular line (anterior/lateral)
V5 - 5th intercostal space in anterior axillary line (lateral)
V6 - 5th intercostal space in midaxillary line (lateral)
what does P-wave correspond with?
depolarization of atrium
what does PR interval correspond with?
time needed for impulse to pass thru AV node
-0.12 to 0.20 seconds
what does QRS complex correspond with?
depolarization of ventricles
-<0.1 second
what does ST segment correspond with?
little electrical activity in heart
what does T wave correspond with?
repolarization of ventricles
