Presentation And Tx Of Acute MI

Question 1

Morphine

Answer 1

Used to control pain associated with acute MI

• reduces afterload and preload
• reducing the preload may improve angina symptoms and chest pain
• controversial useage since some studies show increased mortality
• primarily used in the setting of angina and MI, is controversial in the use of Heart block and hypotension due to decreasing blood pressure*
• however for testing and boards purposes, use morphine for these incidents

Question 2

Treatment of STEMIs

Answer 2

Need treatment before 3hrs

• 50% reduction in mortality if treated before 3 hrs
• can treat up to 12 hrs after onset of symptoms

Goal of treatment is to limit infarct size and preserve left ventricular function

Treatment options =

1) fibrinolysis ( only serious incidents)
- requires door-needle time less than 30 min
- includes tenecteplase or reteplase w/ coadministration of HMW heparin or P2Y12 inhibitors

2) percutaneous coronary interventions (STENTS Or valvular angioplasty)
- this is preferred option unless it cant be done

Question 3

Contraindications of fibrinolysis drugs (tPA)

Answer 3

History of brain hemorrhages

History of strokes less than 3 months ago

Aortic dissection is likely

Active bleeding currently

Severe uncontrolled hypertension (>180/>110)
- must fix first, then treat

Significant head trauma

Question 4

Indications for fibrinolytic therapy

Answer 4

1) Onset of STEMI within 12 hrs without contraindications
- most effective within 90 min of symptoms

2) new LBBBs

Question 5

PCI

Answer 5

Includes angioplasty, valvuloplasty and stenting

• often used in acute coronary syndromes over tPA (unless PCI cannot be done within 90 minutes) since it has low contraindications
• must use in cardiogenic shock

also requires duel anti-platlet therapy for 12 months (asprin and P2Y12 inhibitor)

Question 6

When to choose PCI over Fibrinolytics?

Answer 6

When in doubt use PCI over fibrinolytics as long as its possible

only time for fibrinolytics is when PCI is not possible within 90 min.
- possess higher mortality so is less safe

Question 7

What rhythm is most common in ECGs after reperfusion?

Answer 7

Accelerated idioventricular rhythm

• this is usually limited and is more of a good sign that treatment worked
• DONT treat, just let it resolve

Question 8

What types of MIs can result in AV blocks?

Answer 8

1) Inferior MI w/or without posterior MI
- blockage of the RCA blocks blood flow to the SA/AV nodes

2) anterior MI
- more dangerous than inferior MI blockage

consider using atropine, however may not respond

Question 9

What type of MI results in LBBB sometimes?

Answer 9

Anterior MI

If MI + new LBBB = treatment for acute MI (lidocaine primarily)

Question 10

Pericarditis

Answer 10

Visceral/parietal layers have infection/inflammation
- pain decreases w/ sitting up

Is called Dressler syndrome if it occurs after post MIs
- generates pericarditis and/or pleural effusions via inflammation or immune related interactions

Question 11

Ventricular aneurysm on an ECG

Answer 11

Persistent ST elevation in the anterior leads often present w/ Q WAVES (PAST MI)

Usually caused by mural thrombosis so treatment consists of anticoagulants to break up the thrombosis

Question 12

Treatment for right ventricular infarct

Answer 12

Blood supply occluded = RCA (85%), left circumflex (15%)

Presents with distended neck veins, clear lungs and hypotension

ECG abnormalities = ST elevation in V1-2 ; ST elevation greater in lead 3 than lead 2

To:

• PCI if severe (shows signs of heart failure)
• IV bolus of lidocaine, BBs or CBBs, fluid overload overtime

DONT use nitrates or morphine (since these increase preload to a failing right ventricle)

Question 13

Tx for post myocardial infarction

Answer 13

Usually Lifelong aspirin and/or P2Y12 (“Grel”)
- If stent placed, must use for 1 yr regardless

BBs are required to be started within 24 hrs after unless contraindications
- often used for life as well

Lifelong statins

Question 14

Why is nitroglycerin used for burning/pain in the chest

Answer 14

Nitrates decrease myocardial preload as their primary effect
- do this by increasing venous capacitance and induce venous pooling

Most pain/burning is caused by increased preload/ oxygen demand is higher than cardiac supply

CONTRAINDICATED in right ventricular infracts

Question 15

Leads that show ST elevation for a septal/anterior MI?

Answer 15

V1-4 will show ST elevation

• Left anterior descending artery is occluded
• just need 2 leads*

Question 16

Leads that show ST elevation for a lateral MI

Answer 16

V5/6 and AVL will show ST elevation

• left circumflex artery is occluded
• just need 2 leads*

Question 17

Leads that show ST elevation for a inferior MI

Answer 17

2/3 and AVF will show ST elevation

• the artery occluded is the RCA
• just need 2 leads*

Question 18

Q waves in ECG

Answer 18

Consistent with previous MIs or with present transmural myocardial infarcts

• if Q waves are present, they will line up with the site of the MI (ex: Q waves in 2/3/AVF = inferior current or past Myocardial infarction)

Question 19

Statistics surrounding missed acute MIs

Answer 19

2-4% of patients are discharged with missing acute MI diagnosis
- accounts for the largest amount of malpractice payouts w/ emergency personal

People who are 1 or more of the following tend to be missed more often

• younger
• woman
• non-white
• poor ECG readings

Question 20

Dresser syndrome

Answer 20

Pericarditis that occurs post MIs

- high chance for pericardial and pleural effusions than normal pericarditis

Question 21

What does mitral regurgitation look like on an ECG?

Answer 21

Will be hypotensive and new holosystolic murmur

ECG changes

• depressed ST in 1/aVL/V3/V4 (around mitral area of the heart)
• ST elevations in aVF/3/2