MI Flashcards

1
Q

Best Discriminator of MI w/n 3 hours of chest pain onset

A

EKG

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2
Q

Transmural MI, injury and myocardial ischemia

A
  • full thickness

- usually L ventricle 2* to coronary artery disease

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3
Q

MI diagnosis

A

At least 2 of 3:

  • symptoms >20min
  • EKG changes (at least 2 leads)
  • Enzyme changes
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4
Q

ST Segment Elevation

>6 months =

A

ventricular aneurysm

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5
Q

After 3 hours best discriminant of MI is

A

creatine kinase MB

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6
Q

Reciprocal EKG changes

A
  • indicative of large MI
  • in leads opposite of TM MI
  • change is transient
  • ST segment depression with T wave upright
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7
Q

Myocardial Ischemia

A
  • Zone of Ischemia: functioning tissue at periphery of infarct
  • T wave increased size & peaked & symmetrical for 1st several hours
  • T wave inverts after 24-48 hours
  • After 1st week T gets upright
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8
Q

Myocardial Injury

A

Zone of Injury: nonfunctional area around infarct

  • indicates acute MI
  • ST Elevation >1mm
  • ST segment normal by 72 hours
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9
Q

Myocardial Infarct

A

Zone of necrosis: irreversible damage at center of MI

  • significant Q wave >0.04 sec (any lead but III & aVr)
  • w/n 48 hours & never go away
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10
Q

EKG with MI

A
  • Significant Q wave (>0.04 sec)
  • occur w/n 48 hours
  • never goes away
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11
Q

EKG with Myocardial Ischemia

A
  • incr T wave; peaked and symmetrical
  • initially & for 1st several hours
  • 24-48 hours after MI: T wave inverts
  • becomes upright after 1st week
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12
Q

EKG with Myocardial Injury

A
  • ST segment elevation
  • > 1mm over baseline (2 small boxes)
  • immediately
  • returned to normal by 72 hours
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13
Q

Potassium

A

resting membrane potential

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14
Q

Calcium

A

threshold potential

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15
Q

Low K+

A

-membrane potential lower

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16
Q

High K+

A

-membrane potential higher

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17
Q

Low Ca++

A

-threshold potential lower

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18
Q

High Ca++

A

-threshold potential higher

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19
Q

Trousseau sign

A
  • (hypocalcemia)

- contraction of hand and fingers with the arterial blood flow of arm occluded for 5 min

20
Q

Chvostek Sign

A
  • hypocalcemia

- tap facial nerve below temple and nose/lip twitches

21
Q

EKG with subendocardial MI

A
  • ST segment depression

- Inverted T wave (deep and symmetrical)

22
Q

Normal Magnesium Levels

A
  • 1.8-3.0 mg/dL

1. 5-2.5 mEq/L

23
Q

Hypomagnesia

A
  • alcoholics or result of multiple electrolyte abnormalities

- can lead to myocardial irritability, A-fib, PVC

24
Q

Subendocardial MI

A

(Non-Q wave MI)

  • partial thickness (inner portion)
  • necrosis is patchy
  • due to relative insufficiency of coronary blood flow
  • ST seg depression
  • Inverted T waves
25
Q

ST Segment depression

A

-Occurs with subencdocardial MI, K+ deficiency, digitalis toxicity with ex’s (if ischemic)

26
Q

Normal K+ levels

A

3.5-5.3 mEq/L

27
Q

Normal Ca++ Levels

A
  • 8.2-10.4 mg/dL

4. 5-5.5 mEq/L

28
Q

Hypercalcemia

A
  • raises threshold potential (decreased excitability)
  • EKG: shortened QRS, depressed T waves

–>heart block

29
Q

Hypocalcemia

A
  • lowers threshold potential (easier to excite)
  • EKG: prolonged QT interval

–>ventricular arrhythmia & cardiac arrest

30
Q

Causes of Hypercalcemia

A
  • thiazide diuretic use
  • acidosis
  • adrenal insufficiency
  • immobility
  • vitamin D excess
31
Q

Causes of Hyperkalemia

A
  • endocrine problems
  • renal problems
  • result of K+ replacement/overdose
32
Q

Causes of Hypokalemia

A
  • use of diuretics
  • vomiting
  • diarrhea
  • sweating
  • alkalosis
33
Q

Causes of Hypocalcemia

A
  • multiple transfusion of titrated blood
  • renal failure
  • alkalosis
  • laxatives
  • antacid abuse
  • parathyroid damage/removal
34
Q

Hyperkalemia

A
  • cell membrane hypopolarized (easier to stim)
  • EKG: narrow, tall T waves, shorter QT interval
  • EKG severe: ST seg depression, prolonged PR, wide QRS

–>v fib or cardiac arrest

35
Q

Hypokalemia

A
  • cell membrane becomes hyperpolarized (harder to excite)
  • EKG: decr T wave amplitude, ST seg depression, P wave peaked, QRS prolonged

–>ventricular arrhythmias

36
Q

Symptoms of Hypercalcemia

A
  • fatigue
  • weakness
  • lethargy
  • anorexia
  • impaired renal function
  • nausea
  • constipation
37
Q

Symptoms of Hypocalcemia

A
  • confusion
  • paresthesia (mouth, digits)
  • Carpal spasm
  • hyperreflexia
38
Q

Anterior Infarct

A

V2, V3 (V4 with greater damage)

Blood Supply: LAD

39
Q

Anteroseptal Infarct

A

V1, V2, V3

Blood Supply: LAD

40
Q

Anterolateral Infarct

A

-V4, V5, V6, I, aVL

Blood: LAD & Circumflex

41
Q

Septal Infarct

A

-Leads V1, V2

Blood: LAD

42
Q

Lateral Infarct

A

I, aVL, V5, V6

Blood: circumflex

43
Q

Inferior Infarct

A

II, III, aVF

Blood: RCA

44
Q

Inferolateral Infarct

A

-II, III, aVF, V5, V6

Blood: RCA & Circumflex

45
Q

Posterior Infarct

A

V1, V2, V3

Blood: posterior descending