Myocardial Ischemia Flashcards
Define myocardial ischemia
An imbalance of oxygen demand and oxygen supply TO THE HEART
What are the 2 targets for increasing O2 supply? Which is more important?
AV oxygen difference
Regional Myocardial distribution (more important
What is the characteristic symptom of myocardial ischemia?
Angina pectoris (chest pain) (due to buildup of metabolites in muscle tissue)
What are the 5 types of myocardial ischemia?
Stable angina (atherosclerotic block of coronary artery)
Unstable Angina (rupture of atherosclerotic plaque)
Silent/Effort Ischemia (asymptomatic until exercise is required)
Variant Angina (no obvious cause, possibly stress)
Myocardial infarction (death of tissue)
Define atherosclerosis
Deposition of fatty substances, esp. cholesterol/fatty acids in arteries
What is a coronary artery spasm?
Surprise death, unknown cause
Where do each of the two types of atherosclerosis take place?
Endothelium-smooth muscle interface
Ruptured lesion in endothelium
Drugs against myocardial ischemia provide one of two effects, what are they?
Reduce O2 demand / improve coronary flow
Slower development of ischemia
Name a nitrate, describe its mechanism of action, and possible side effects
Nitroglycerin
Increases cAMP through GPCR cascade, which leads to muscle relaxation
-> reduction of venous return, cardiac size & diastolic myocardial oxygen consumption
- Orthostatic hypotension
- Tachycardia
- Headache
Name 3 calcium channel blockers, describe their mechanism of action, and list possible side effects
Verapamil
Nifedipine
Diltiazem
peripheral vasodilation, reduction of cardiac work
- Orthostatic hypotension
- AV blockade
- Edema
Name a beta blocker, describe its mechanism of action, and possible side effects
Propranolol
Reduces blood pressure/cardiac work
- Orthostatic hypotension
- Tachycardia
- Headache
What drugs would be prescribed for someone with effort Angina?
Nitrates Ca channel blockers (prophylactic) Beta blockers (v important)
What drugs would be prescribed for someone with Variant angina?
NItrates
Ca channel blockers (prophylactic)
What drugs would be prescribed for someone with Acute Coronary Syndrome?
Nitrates Beta blockers (very important)
True/False? Drugs are the only way to prevent atherosclerosis
False (lots of ways to control, but people avoid them because they require effort)
How do statins help with myocardial ischemia?
Reduces cholesterol synthesis (which is what plaques are made of)
True/False? HDL are considered “bad” lipoproteins because they send cholesterol into tissues where they can accumulate
False
Name a statin, its mechanism of action and its potential side effects
Lovastatin
Inhibits HMG-Co-A reductase (blocks de novo synthesis of cholesterol)
May damage skeletal muscle or liver, interferes with myelination of infants
Name a resin, its mechanism of action, and its potential side effects
Cholestyramine
Bind to cholesterol and prevent reabsorption from gut
- unpleasant taste
- Upsets GI
- Interferes with vitamin/drug absorption
What is Niacin, what does it do, and what are its side effects?
Vitamin B3 (nicotinic acid)
Action not well understood, but it decreases secretion of VLDL in liver
- Occasional flush with itching
- Rarely causes glucose intolerance
Name a fibrate, describe its mechanism of action, and list its potential side effects
Gemfibrozil
Activates peroxisome proliferation-activated receptor-alpha which increases lipoprotein lipase synthesis
- Nausea
- Skin Rash
- Occasional increased risk of gallstones
What are the 3 options to prevent thrombus aggregation?
- Inhibition of platelet function
- Inhibition of blood coagulation
- Stimulate lysis of pre-formed thrombus
Name two drugs that inhibit blood coagulation, their mechanismS, and potential side effects
Warfarin:
- Blocks reactivation of vitamin K epoxide
- Teratogenic, bleeding
Heparin:
- Binds coagulation factor Xa and antithrombin III
- Bleeding
What is the prothrombin time test?
Prick your finger and time how long it takes to clot
What is the difference between HMW heparin and LMW heparin?
HMW heparin binds coagulation factor Xa and antithrombin III, inactivating them (effect must be monitored, used in hospitals)
LMW heparin inhibits factor Xa, but has less effect on antithrombin III (predictable response, doesn’t have to be monitored)
Name 2 fibrinolytic drugs, describe their mechanisms and their potential side effects
Streptokinase -> Tissue Plasminogen Activators (tPA)
Converts plasminogen to plasmin (streptokinase, $)
-plasmin breaks down thrombi
Activation of plasminogen bound to fibrin (tPA, $$$)
- Allergic response (streptokinase)
- Bleeding (both)
Name two cyclooxygenase inhibitors, describe its mechanism, and possible side effects
Aspirin (irreversible), ibuprofen (competitive)
Inhibits platelet cyclooxygenase, blocking synthesis of thromboxane A2
- Bleeding
- GI ulceration (aspirin)
Name an adenosine receptor blocker, describe its mechanism, and possible side effects
Ticlopidine
Alternative to aspirin (when allergic), inhibits platelet response to secreted ADP at adenosine receptors
- Bleeding
- Skin Rashes
List 3 drugs that reduce O2 demand/improve coronary flow
- Nitrates
- Ca channel blockers
- beta-blockers
List 2 drug classes that slow the development of myocardial ischemia
- Lipid lowering drugs
- Drugs affecting coagulation, fibrinolysis, platelet aggregation
