5 - ECG at the Bedside 2 Flashcards
good guideline for a normal length of a QT interval
if its is less than or equal to 1/2 of RR interval, you can be pretty confident that it is not prolonged
ECG criteria for LVH
left axis deviation
R (V5/6) + S (V1/2) > 35 mm
ECG criteria for RVH
right axis deviation
tall R in V1/2 > 5 mm OR R>S
What ECG finding is suggestive (but not diagnostic) of eccentric hypertrophy?
bundle branch block
pathologic q waves - meaning and definition
indicate old MI in that area
features: wider than 40 ms, deeper than 1/3 of R wave in same lead
what do ST segment elevation and depression most commonly indicate, respectively?
elevation - acute MI
depression - subendocardial ischemia
which type of ST depression is most specific for subendocardial ischemia?
a. downsloping
b. horizontal
c. upsloping
d. a and b
d
when does upsloping ST depression occur?
can be normal during cardiac stress
what condition tends to cause subendocardial ischemia?
CAD
causes of ST elevation (4)
acute MI
coronary vasospasm (prinzmetal angina)
acute pericarditis
early repolarization
how do you distinguish between acute MI and pericarditis by ECG?
acute MI - localized ST elevation, pathologic Q waves, NO PR depression
acute pericarditis - diffuse ST elevation, no pathologic q waves, PR depression
what is the timeline of ECG changes after an MI?
immediately - ST elevation
after a few hours - t wave inversion and pathologic q waves
q waves will decrease over time and become only slightly abnormal. t wave inversion will go away completely after the event
significance of T wave inversions
myocardial ischemia
LVH/RVH
BBB
digoxin
significance of tall T waves
myocardial ischemia
acute MI
hyperkalemia
2 kinds of abnormal R wave progression
early R/S transition - bigger R wave in V1/2
late R/S transition - smaller R waves in V5/6
