What is the difference between STEMI and Angina Pectoris?

Angina Pectoris is partial occlusion of the coronary artery and and pain that accompanies. STEMI is the complete occlusion of the coronary artery which causes a much larger area of infaction.

Why is it called STEMI?

What are the risk factors for STEMI?

• ↑ age
• family hx of MI
• sedentary lifestyle
• obesity
• high serum cholesterol
• HTN
• smoking diabetes

Pathophysiology of STEMI

• blood flow is stopped due to platelet plugging and thrombus formation in a coronary artery, (almost always at the site of a fissure or ruptured atherosclerotic plaque) causing an imbalance of O₂  demand and O₂ supply  
• due to the ischemia, a dramatic redistribution of ions takes place- H ions accumulate in the myocardium and Ca ions are sequestered in the mitochondria
• This results in acidosis and functional Ca deficiency, which alters the distensibility of cardiac muscle
• Na ions accumulate in the myocardial cells and promote edema
• K ions are lost from myocardial cells, thereby causing dysrhythmia
• metabolism shifts from aerobic to anaerobic
• High-energy stores of ATP and creatinine phosphate become depleted, and contraction ceases in affected region
• if blood flow is not restored, cell death begins in 20 minutes    

How is STEMI diagnosed?

• Chest pain- severe substernal pressure for 20 to 30 minutes and nitroglycerin is ineffective
• characteristic ECG changes- elevation of the ST segment
• elevated serum levels of cardiac troponins

Why is it recommended for people to chew an aspirin if they suspect they are having an MI?  

Aspiring suppresses platelet aggregation and thereby decreases mortality, reinfarction, and stroke

How does IVP morphine sulfate help the person experiencing an acute MI

Morphine is given for pain as well as to improve hemodynamics by promoting venodilation. Venodilation will will reduce cardiac preload.

Why do patients with suspected STEMI receive supplemental oxygen?

Supplemental oxygen , administered by nasal cannula, can increase arterial oxygen saturation, and thereby increase oxygen delivery to the the ischemic myocardium

**2-4 L /nasal cannula should be given to all patients with O₂ saturation below 90% and to all other patients with suspected STEMI as well.

What is considered "routine therapy" for patients with suspected STEMI?

• Oxygen 2-4 L/nasal cannula- ↑O₂ to MI site
• Aspirin (162-325 mg )chewed- suppress platelet aggregation (antithrombotic effect) 
• Morphine- for pain & improves hemodynamics through venodilation- reduces cardiac preoad and through arterial dilation reduces afterload; together lowers cardiac O₂ demand
• Beta Blockers- ↓cardiac pain, infarct size, and short-term mortality
• Nitroglycerin- ↓ preload = ↓O₂ demand,    ↑ collateral blood flow to ischemic region, controls HTN caused by STEMI associated anxiety, and limits infarct size and improves LV function

Beta blocker, as they

• reduce cardiac pain
• infarct size, short-term mortality
• recurrent ishemia
• reinfarction
• and continued use increases long term survival

Why are ACE inhibitors prescribed to treat STEMI?

• decrease short term mortality in all patients
• decrease long-term mortality in patients with reduced LV function
• ↓ preload and afterload
• promotes water loss 
• prevents ventricular remodeling

What are adverse effects of using ACE inhibitors in STEMI patients?

• hypotension
• cough

What is Reperfusion Therapy?

What is the difference between fibrolytic therapy and percutaneous coronary intervention (PCI)?

Fibrolytic Therapy

• universal access
• shorter time to treat
• results are less dependent on physician experience
• lower cost

What is fibrolytic therapy and what drugs are used and how to they work?

Fibrolytic therapy is the use of drugs; alteplase, reteplase, streptokinase, tenecteplase, and urokinase, to dissolve clots.

Fibrinolytic drugs work by converting plasminogen into plasmin, an enzyme that digests fibrin meshwork that holds clots together

Under typical conditions, all the fibrolytics are equally beneficial. However, under ideal conditions, alteplase is most effective in pt. under 75. All pt. undergoing fibrolytic therapy should receive an anticoagualnt (IV heparin) plus antiplatelet druns (aspirin plus clopidogrel) 

Bleeding; intracranial pressure is the greatest concern

• Heparin- anticoagulant
• Clopidogrel combined with aspirin- antiplatelets
• Glycoprotein IIb/IIIa inhibitors- antiplatelet