MI

Question 1

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

Answer 1

EKG

Question 2

Transmural MI, injury and myocardial ischemia

Answer 2

• full thickness

- usually L ventricle 2* to coronary artery disease

Question 3

MI diagnosis

Answer 3

At least 2 of 3:

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

Question 4

ST Segment Elevation

>6 months =

Answer 4

ventricular aneurysm

Question 5

After 3 hours best discriminant of MI is

Answer 5

creatine kinase MB

Question 6

Reciprocal EKG changes

Answer 6

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

Question 7

Myocardial Ischemia

Answer 7

• 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

Question 8

Myocardial Injury

Answer 8

Zone of Injury: nonfunctional area around infarct

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

Question 9

Myocardial Infarct

Answer 9

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

Question 10

EKG with MI

Answer 10

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

Question 11

EKG with Myocardial Ischemia

Answer 11

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

Question 12

EKG with Myocardial Injury

Answer 12

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

Question 13

Potassium

Answer 13

resting membrane potential

Question 14

Calcium

Answer 14

threshold potential

Question 15

Low K+

Answer 15

-membrane potential lower

Question 16

High K+

Answer 16

-membrane potential higher

Question 17

Low Ca++

Answer 17

-threshold potential lower

Question 18

High Ca++

Answer 18

-threshold potential higher

Question 19

Trousseau sign

Answer 19

• (hypocalcemia)

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

Question 20

Chvostek Sign

Answer 20

• hypocalcemia

- tap facial nerve below temple and nose/lip twitches

Question 21

EKG with subendocardial MI

Answer 21

• ST segment depression

- Inverted T wave (deep and symmetrical)

Question 22

Normal Magnesium Levels

Answer 22

• 1.8-3.0 mg/dL

1. 5-2.5 mEq/L

Question 23

Hypomagnesia

Answer 23

• alcoholics or result of multiple electrolyte abnormalities

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

Question 24

Subendocardial MI

Answer 24

(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

Question 25

ST Segment depression

Answer 25

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

Question 26

Normal K+ levels

Answer 26

3.5-5.3 mEq/L

Question 27

Normal Ca++ Levels

Answer 27

- 8.2-10.4 mg/dL | 4. 5-5.5 mEq/L

Question 28

Hypercalcemia

Answer 28

- raises threshold potential (decreased excitability) - EKG: shortened QRS, depressed T waves -->heart block

Question 29

Hypocalcemia

Answer 29

- lowers threshold potential (easier to excite) - EKG: prolonged QT interval -->ventricular arrhythmia & cardiac arrest

Question 30

Causes of Hypercalcemia

Answer 30

- thiazide diuretic use - acidosis - adrenal insufficiency - immobility - vitamin D excess

Question 31

Causes of Hyperkalemia

Answer 31

- endocrine problems - renal problems - result of K+ replacement/overdose

Question 32

Causes of Hypokalemia

Answer 32

- use of diuretics - vomiting - diarrhea - sweating - alkalosis

Question 33

Causes of Hypocalcemia

Answer 33

- multiple transfusion of titrated blood - renal failure - alkalosis - laxatives - antacid abuse - parathyroid damage/removal

Question 34

Hyperkalemia

Answer 34

- 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

Question 35

Hypokalemia

Answer 35

- cell membrane becomes hyperpolarized (harder to excite) - EKG: decr T wave amplitude, ST seg depression, P wave peaked, QRS prolonged -->ventricular arrhythmias

Question 36

Symptoms of Hypercalcemia

Answer 36

- fatigue - weakness - lethargy - anorexia - impaired renal function - nausea - constipation

Question 37

Symptoms of Hypocalcemia

Answer 37

- confusion - paresthesia (mouth, digits) - Carpal spasm - hyperreflexia

Question 38

Anterior Infarct

Answer 38

V2, V3 (V4 with greater damage) Blood Supply: LAD

Question 39

Anteroseptal Infarct

Answer 39

V1, V2, V3 Blood Supply: LAD

Question 40

Anterolateral Infarct

Answer 40

-V4, V5, V6, I, aVL Blood: LAD & Circumflex

Question 41

Septal Infarct

Answer 41

-Leads V1, V2 Blood: LAD

Question 42

Lateral Infarct

Answer 42

I, aVL, V5, V6 Blood: circumflex

Question 43

Inferior Infarct

Answer 43

II, III, aVF Blood: RCA

Question 44

Inferolateral Infarct

Answer 44

-II, III, aVF, V5, V6 Blood: RCA & Circumflex

Question 45

Posterior Infarct

Answer 45

V1, V2, V3 Blood: posterior descending