Calibrating EKG Flashcards
Paper speed
25mm/s one mm square is 0.04 seconds
10 1mm squares vertically
one millivolt
one-millivolt calibration
square shaped signal should appear over approx. 10 mm horizontally and 10 mm vertically
Einthoven’s Triangle placement
right arm, left arm, left leg
electrical potential of Lead I plus lead III = lead II
EKG troubleshooting techniques
recognize potential sources of artifacts
verify that all equipment is working properly
check electrode placement and skin quality
right arm right leg electrode reversal
“isoelectric lead II”
lead II normally detects difference between left leg and right arm, in this case it would be difference between left and right leg, potential is virtually the same so lead II will show almost no activity
leads I and III will be mirror images of each other (equal opposite amp)
Right and left arm reversal
lead I: will show inverted P wave and inverted QRS complex compared to V6,
lead II: will appear as a normal lead III
lead III: will appear as a normal lead II
aVL: will look like aVR
aVR: will look like aVL
left arm right leg reversal
Lead III will be virtually isoelectric, almost no electrical activity
leads I and II will be equal but opposite
aVF and aVR will resemble each other
left arm left leg reversal
difficult to detect
Lead III will be inverted compared to normal tracings
aVL will be interpreted as aVF and vice versa
lead I and lead II will be interpreted as each other
often not noticed until other EKG’s are compared
right arm left leg reversal
aVF will resemble normal aVR, P wave in aVF will be inverted, will lead to an incorrect diagnosis of MI
V1 V2 placement
4th intercostal space
if too high: p wave is inverted, T wave inverted, R wave after S wave, will look like BBB or ventricular hypertrophy
V2 V3 reversal
abnormal R wave, R wave will not increase in amplitude from V2-V4
S wave in V3 will be larger than S wave in V2
Dextrocardia lead placement
everything is placed as a mirror image
Wandering Baseline
result of poor electrode contact with skin
skin must be clean, dry, no abnormalities or abrasions at the site, occurs gradually
Shifting Baseline
sudden loss of contact with skin
