Myocardial Infarction

Question 0

Chest pain in MI

Answer 0

Similar to angina but it is :
Sever
At rest - prolonged
Not responding to nitrate

Question 1

Myocardial infarction

Answer 1

Complete cessation of coronary perfusion

Occlusive thrombus on top of rupture or erosion of atheromatous plague

Ischemic necrosis –> localized area of the myocardium

Question 2

Clinical picture MI

Answer 2

Chest pain

Anxiety ( fear of impending death)

Sympathetic stimulation [pallor, sweating, increased HR]

Vagal stimulation [ vomiting, bradycardia ] common in inferior wall infarction

Hypotension ( with nitrate use)
Sinus tachycardia, 4th HS, raised jagular venous pressure

Manifestation of complications

Question 3

Painless infarction

Answer 3

Diabetic neuropathy

Infarction with pulmonary edema

Infarction during coma

Elderly

Infarction during anesthesia

Transplanted heart ( denervated)

Question 4

Pulmonary edema with MI

How??

Answer 4

Extensive MI > Lt. VF > acute pulmonary edema

Rupture papillary muscle > acute sever MR > backward failure

Question 5

Types of MI

Answer 5

Transmural ( full thickness)

Subendocardial ( inner one third to one half)

Question 6

Sites of MI

Answer 6

Anterior wall ( anterior descending branch )

Lateral wall ( left circumflex )

Inferior wall ( right coronary)

Question 7

ECG changes in MI

Answer 7

After 6 hr

**Transmural infarction
S-T segment elevation
Pathological Q wave
Inverted T wave

** subendocardial infarction ( non Q infarction )
S-T segment depression
Inverted T

Question 8

Enzymes and biomarkers for MI

Answer 8

CK

AST
LDH

Cardiac troponins T and I

Myoglobins

Question 9

Creatine kinase changes in MI

Answer 9

Onset 4-6 hr
Peak 12 hr
Duration 2-3 days

Ask for specific CK enzyme for MI ( CK-MB fraction)

Question 10

AST and LDH level changes in MI

Answer 10

AST
Onset 12 hr
Peak 1 day
Duration 3 days

LDH
Onset 12 hr
Peak 2 days
Duration 1 week

Question 11

Cardiac troponins T and I

features over other markers

Answer 11

Very specific

Released early 4-6 hr

Persist for up to 7-14 days

Question 12

Myoglobins changes in MI

Answer 12

Detected within 2 hr

Remains for 24 hr

Question 13

Echo values in MI

Answer 13

Showing VSD, ruptured inter ventricular septum, pericardial effusion, MR,

Also detects ejection fraction ( prognostic value)

Question 14

Uncomplicated MI

Answer 14

No associated arrhythmia or heart failure

Heamodynamically stable patient

Question 15

Treatment of uncomplicated MI

Answer 15

First aid

• rest , reassurance
• O2 therapy
• sublingual nitrates
• sedation, analgesia

In hospital

• CCU
• ECG monitoring
• Morphia 5-10 mg IV ( lanoxone must be available )
• IV cannula with 5% glucose IV drip very slowly
• mini dose heparin or antiplatelete, LMWH is safe
• metoclopramide IV if required
• O2 2-4 L/m to maintain saturation > 90%
• measures to limits the size of infarction or to reverse it within the first 6 hours ( IV BB, nitrates infusion, thrombolytic therapy)
• ACE inhibitors ( reduction of ventricular remodeling )
• adjust serum Mg ( reduce risk of arrhythmia )

Question 16

Nitrates infusion in treatment of MI

Answer 16

Systolic BP > 100 mgHg
To treat lt. VF and relieve of recurrent or persistent ischemic pain

Nitroglycerin 0.6-1.2 mg/h

Question 17

Thrombolytic therapy ( reperfusion)

Answer 17

Streptokinase 1-1.5 million units in 100 ml saline IV over 1 hr

Urokinase