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AHN 568 Unit 1 Test with Questions and Answers| Latest Update
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AHN 568 Unit 1 Test with Questions and Answers| Latest Update
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AHN 568 Unit 1 Test with Questions and Answers|Latest Update
§ What is occurring from a conduction standpoint?
The wall of the RV is very thick, so there is a much more positive depolarization (and more
vectors) towards the positive V1 electrode; therefore, we expect the QRS in lead V1 to be more
positive (taller) than usual
left ventricular hypertrophy - ✔✔Main Critera
o S wave depth in V1 or V2 (whichever is deepest) + R wave height in V5 or V6 (whichever is
tallest) is greater or equal to 35mm
o LAD with slightly widened QRS
o Leftward rotation in the horizontal plane
o Strain pattern à asymmetrical, down sloping T wave in some patients depending on pathology
**** these criteria are only valid if electrical conduction occurs via the normal pathway****
What is occurring from a conduction standpoint?
o Normally the S wave in V1 is deep, but with LVH even more depolarization is going downward
to the patient's left (away from the positive V1 electrode). This causes the S wave to be even
deeper in V1.
Right Atrial Enlargement - ✔✔Criteria:
o Initial component of the diphasic P wave in lead V1 is larger
o Suspect RAH if the height of the p wave in any limb lead > 2.5mm
§ What is occurring from a conduction standpoint?
o The amplitude of the P wave is exaggerated due to the close proximity of the hypertrophied
right atrial myocardium to the SA node. (Action potentials travel quicker)
,Left Atrial Enlargement - ✔✔Criteria:
o Terminal component of p wave in V1 is large and wide
Most common cause = systemic hypertension, but can also be caused by mitral stenosis
What is occurring from a conduction standpoint?
o Action potentials are travel slower through the atrial myocardium, lengthening the P wave
Right Bundle Branch Block - ✔✔Criteria:
o QRS > or equal to 0.12 sec
o R,R' in the right chest leas V1 or V2
o Slurred S wave in I and V6 (most important)
What is occurring from a conduction standpoint?
o RV depolarization is delayed
o LV depolarization is punctual, so the R represents the LV and the R¹ represents the delayed RV
depolarization
Left Bundle Branch Block - ✔✔Criteria:
o QRS > or equal to 0.12 sec
o Broad, monomorphic R wave in I and V6 that are either both + or -
o Broad, monomorphic S wave in V1
o R,R¹ in the left chest leads V5 or V6.
What is occurring from a conduction standpoint?
o The RV depolarizes before the LV, so the first portion of the wide QRS represents RV
depolarization
, Left Anterior Hemiblock - ✔✔Most common type of Hemiblock
· Commonly associated with LAD (always r/o pre-existing sources of LAD first)
· Normal or slightly widened QRS
· QıS3 à Finding a Q in I and wide and/or deep S in III confirms diagnosis
Posterior Hemiblock - ✔✔RARE!
· Deep/unusually wide S in I and Q in III (SıQ3)
· Serious, especially w/ RBBBà can progress to AV Blocks
· RAD
bifascicular block - ✔✔RBBB + either an Anterior or Posterior Hemiblock
EKG Changes with Coronary Ischemia - ✔✔reversible; ischemic area is more negative
electrically than surrounding tissue → ST depression
abnormal pathway of repolarization → T wave inversion;
affects a wedge-shaped section of the heart; increase in O2 demand or decrease/blockage of
supply
EKG Changes with Coronary Injury - ✔✔reversible; wedge-shaped zone of injury with tissue
damage similar to ischemia; zone of injury does not re-polarize completely and remains more
positive than surrounding tissue → ST elevation
abnormal repolarization pathway - inverted T wave
EKG Changes with Coronary Infarction - ✔✔NOT reversible; dead tissue is unable to generate
action potentials and act as an electrical window through the myocardium; causes:
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