Ch. 9: Infarction

Question 1

what is an infarction?

Answer 1

• complete occlusion of coronary artery
• necrosis
• no depolarization
• no contraction
• heart gets blood supply from coronary arteries
• blockage= myocardium has no blood supply
• PRIMARILY LEFT VENTRICLE

Question 2

how are infarctions diagnosed?

Answer 2

• history and physical exams
• cardiac enzymes
• EKG

Question 3

how will an EKG possibly show an infarction?

Answer 3

• which coronary artery is blocked
• reveal conduction blocks caused by infarction
• reveal reduced blood supply to heart

Question 4

what is the same as an infarction?

Answer 4

• myocardial infarction
• coronary occlusion
• heart attack

Question 5

what is necrotic tissue?

Answer 5

• functionally dead
• no depolarization
• may compromise hemodynamics

Question 6

what is the Infarction Triad?

Answer 6

• Ischemia (lack of blood flow)
• Injury (to heart tissue)
• Necrosis (dead tissue)
• basis for recognizing and diagnosing MI

Question 7

What is Ischemia?

Answer 7

• lack of blood flow
• Pathological
• may cause enigma

Question 8

How do you identify Ischemia?

Answer 8

• Inverted T wave in absence of MI
• inverted T wave and symmetrical
• T wave inversion V2-V6

Question 9

Injury

Answer 9

• acuteness of infarction
• ST seg elevation
• may be slight
• may be >10mm

Question 10

ST elevation

Answer 10

• alone may indicate infarction
• acute
• over time ST elevation returns to baseline
• Ventricular aneurysm may cause persistent ST elevation in most chest leads

Question 11

ST depression

Answer 11

• subendocardial infarction
• positive stress test
• digitalis
• angina attack

Question 12

When does ST depression occur?

Answer 12

• with ischema
• ventricular strain
• electrolyte abnormality
• subendocardial infarction
• elevated rate

Question 13

J Point (Junctional Point)

Answer 13

• end of QRS and beg. of ST set
• elevation is common in young, healthy indivs
• measure ST seg depression 80 sec past J point

Question 14

Subendocardial Infarction

Answer 14

• ST depression
• Flat, Horizontal, Downward sloping
• Non Q wave infarction
• small area just beneath endocardial lining

Question 15

Necrosis

Answer 15

• Q wave
• significant
• at least 0.04s in duration
• at least 1/3 of QRS amp
• height and depth

Question 16

How to identify infarctions

Answer 16

• scan all leads except QVR for:
• Q waves
• ST seg depression or elevation
• inverted T waves

Question 17

Anterior Infarction

Answer 17

• positive chest leads record negative
• V1-V4
• Q wave
• anterior descending art

Question 18

Lateral Infarction

Answer 18

• positive L arm leads record negative
• Lead 1 and AVL
• Q wave
• occlusion of circumflex art

Question 19

Inferior Infarction

Answer 19

• Positive L arm leads record negative
• Leads 2, 3, and AVF
• Q wave
• terminal branch of either R/L CA

Question 20

Posterior Infarction

Answer 20

• ST depression
• V1 and V2
• Large/Tall R waves
• may be Q in V6
• R coronary art

Question 21

Coronary arteries

Answer 21

• L coronary artery: Circumflex and Anterior Descending
• R coronary artery

Question 22

Left ventricle (lateral)

Answer 22

• Q wave
• Lead 1
• AVL

Question 23

Left ventricle (anterior)

Answer 23

• Q wave
• V1
• V2
• V3
• V4

Question 24

Antero-septal (septum)

Answer 24

• Q waves
• V1
• V2
  (negative QRS in V1-V4, V5-V6 norm have insignif Q waves)

Question 25

Antero-lateral

Answer 25

- Q waves - V3 - V4 (negative QRS in V1-V4, V5-V6 norm have insignif Q waves)

Question 25

Antero-lateral

Answer 25

- Q waves - V3 - V4

Question 26

T/F: anterior infarctions are very deadly

Answer 26

T: widow maker. immediate treatment improves survival

Question 27

Lateral Infarct

Answer 27

- depolarization away from positive leads - Lateral L ventricle involved - Q wave - Lead 1 - AVL

Question 28

Inferior infarction

Answer 28

- depolarization away from positive leads - 2, 3, AVF negative sometimes - inferior wall of L ventricle involved - Q wave - Lead 2 - Lead 3 - AVF

Question 29

Acute Anterior infarction

Answer 29

- V1-V4 still negative - ST elevation - significant Q waves - V1 - V2 - w/ possible significant Q waves in V1 and V2

Question 30

Acute posterior infarct

Answer 30

- ST depression - same as posterior infarct, difficult to diagnose on EKG - Large R wave - V1 - V2

Question 31

Hemiblock

Answer 31

- Leads to MI, hard to identify on EKG - associated with decreased blood supply - LBB- 2 divisions - anterior and posterior

Question 32

Hemiblock (anterior)

Answer 32

- LAD - normal or slightly widened QRS - Large Q wave in lead 1 - Large S wave in Lead 3 - occluded anterior descending coronary art - anterior infarction (1/2 develop anterior hemiblock)

Question 33

Posterior hemiblock

Answer 33

- RAD - normal or slightly widened QRS - Large S wave in Lead 1 - Large Q wave in Lead 3