EKG 3 - LVH, Infarcts, & Ischemia

Question 1

left ventricular hypertrophy - EKG findings

Answer 1

*several ways to classify:
1. add S wave amplitude from V1 + R wave amplitude from V5 or V6; if > 35 mm, then LVH
2. R wave in lead 1 >12 mm
3. R wave in aVL > 11 mm
4. any precordial lead > 45 mm

*asymmetric T wave inversions

note - do NOT diagnose anyone < 35 yo with LVH by EKG alone

Question 2

right ventricular hypertrophy - EKG findings

Answer 2

*requires BOTH of the following:
1. POSITIVE QRS in lead V1 (R > S)
2. RIGHT AXIS DEVIATION (negative QRS in lead 1, positive in aVF)

Question 3

inferior leads

Answer 3

*leads: II, III, and aVF
*ST elevations in these leads classically associated with obstruction of RCA

Question 4

septal leads

Answer 4

leads: V1, V2

Question 5

anterior leads

Answer 5

*leads: V2, V3, V4
*ST segment elevation in these leads is classically associated with obstruction of the LAD

Question 6

anterolateral leads

Answer 6

leads: V5, V6
classically associated with left circumflex artery

Question 7

lateral leads

Answer 7

leads: I, aVL
classically associated with LAD

Question 8

coronary artery involved with leads II, III, and aVF

Answer 8

right coronary artery (RCA)

Question 9

coronary artery involved with leads V1-V6

Answer 9

left anterior descending artery (LAD)

Question 10

coronary artery involved with leads I, aVL

Answer 10

left circumflex artery (LCx)

Question 11

significant Q waves indicate ?

Answer 11

*heart attack in the DISTANT PAST (dead cells)
*significant Q waves: if Q wave height is > 25% of the total height of the QRS
*if cells are completely dead, then they do not conduct electricity
*the signal in a lead near an infarct will have a negative inflection

Question 12

ST elevations - overview

Answer 12

*TRANSMURAL INJURIES cause ST elevation in the electrodes close to the affected region
*transmural injury indicates an acute, COMPLETE occlusion of a coronary artery
*this is what classifies a STEMI

Question 13

reciprocal ST depressions - overview

Answer 13

*a lead recording “opposite” to the transmural ischemia will show ST depression
*this is just an electrical phenomenon
*the area showing the ST depression most likely reflects ischemia on the opposite side of the heart

Question 14

convex ST elevations

Answer 14

*more suggestive of acute MI
*draw a line from the end of the QRS to the peak of T wave; if ST elevation is ABOVE THAT LINE, it is convex
*also referred to as “tombstoning”

Question 15

differences in EKG findings for an ACUTE STEMI vs. an MI that happened a long time ago

Answer 15

*ACUTE = ST elevations
*long time ago = significant Q waves

Question 16

ST elevations in leads I and aVL

Answer 16

*lateral / anterolateral MI
*artery = CIRCUMFLEX

Question 17

ST elevations in leads V1-V6

Answer 17

*ANTERIOR MI
*artery = left anterior descending (LAD)

Question 18

ST elevations in leads II, III, and aVF

Answer 18

*INFERIOR MI
*artery = right coronary artery (RCA)

Question 19

characterizing inferior STEMIs

Answer 19

*inferior STEMIs = ST elevations in leads II, III, and aVF
*need to look at lead V1:
-if ST elevations also in V1, inferior MI with right ventricular involvement
-if ST depressions in V1, inferior MI with POSTERIOR (PDA) involvement

Question 20

ST elevations in leads II, III, aVF & ST elevations in V1

Answer 20

*inferior STEMI (right coronary artery) with right ventricular involvement

Question 21

ST elevations in leads II, III, and aVF & ST depressions in V1

Answer 21

*inferior STEMI (right coronary artery) with posterior involvement (PDA)

Question 22

lateral / anterolateral STEMI

Answer 22

*ST elevations in leads I and aVL
*artery = circumflex

Question 23

anterior STEMI

Answer 23

*ST elevations in V1 - V6
*artery = LAD

Question 24

inferior STEMI

Answer 24

*ST elevations in leads II, III, and aVF

*look at V1:
-elevations in V1 = significant RV involvement
-depressions in V1 = posterior involvement (PDA)

Question 25

ST depressions - overview

Answer 25

*ischemia WITHOUT TRASNMURAL INFARCTION (not a complete infarction) tends to affect the subendocardium
*can be a sign of ischemia alone or of a NON-ST elevation MI (NSTEMI)

Question 26

symmetric vs. asymmetric T wave inversions

Answer 26

*asymmetric T wave inversions - associated with left ventricular hypertrophy (LVH)

*SYMMETRIC T wave inversions - associated with ISCHEMIA

-note: a T wave inversion is symmetric if you draw a line through it and it looks the same on both sides

Question 27

EKG findings of acute pericarditis

Answer 27

*GLOBAL ST segment elevation
*PR interval depression

Question 28

early hyperkalemia - EKG findings

Answer 28

*peak T waves (T waves very large, larger than QRS)

note - hyperkalemia is INCREASED potassium

Question 29

severe/late hyperkalemia - EKG findings

Answer 29

*peak T waves + WIDENED QRS + flattened P wave

note - hyperkalemia is INCREASED potassium

Question 30

marked HYPOkalemia - EKG findings

Answer 30

*prominent “U” waves (extra bump after the T wave)