Term
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Definition
| chest pain caused by cardiac ischaemia, generally due to obstruction or spasm of the coronary arteries |
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Term
| What are the symptoms of angina? |
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Definition
- pain in chest which radiates to the arm, neck and jaw and is intermittent, often with exertion
- pain is also brought on with cold or excitement |
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Term
| What are the causes of angina? |
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Definition
- coronary blood flow is insufficient to supply the O2 requirements of the myocardium
- O2 demands of the heart are high
- CAD is due to atherosclerosis |
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Term
| Define collaterals and give their importance |
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Definition
| connect arterial systems derived from different major coronary arteries. Number of collaterals can be increased via exercise. More collaterals = more protection from blockage. Age also increases collaterals. |
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Term
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Definition
| from the sub0epicardial (outer) surface to the sub-endocardial (inner) surface |
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Term
| What are the main physiological factors that regulate coronary flow? |
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Definition
- physical factors
- vascular control by metabolites
- neural and humoral control |
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Term
| What part of the heart is vunerable to changes in coronary flow? |
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Definition
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Term
| When does the majority of coronary blood flow occur? |
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Definition
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Term
| What affect does aortic pressure have on coronary blood flow have? |
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Definition
| perfuses the coronary capillaries |
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Term
| What affect does ventricular pressure have on coronary blood flow have? |
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Definition
| prevents perfusion by compressing coronary capillaries |
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Term
| What are the 3 types of angina? |
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Definition
Stable
Unstable
Prizmental's |
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Term
| What causes stable angina? |
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Definition
| - increased demand on the heart and is caused by a fixed narrowing (atherosclerosis) |
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Term
| What causes unstable angina? |
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Definition
| - atherosclerotic plaque ruptures, thrombi occlude artery |
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Term
| What causes Varient (Prinzmetal's) angina? |
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Definition
- uncommon and unpredictable
- occurs at rest and is a coronary spasm
- possibly due to increased extracellular K+ or Ca2+ -> membrane depolarisation |
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Term
| What does angina lead to? |
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Definition
other cardiac diseases
- necrosis/apoptosis
- acute myocardial infarction
- HF and dysrhythmias
- Death |
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Term
| What do drugs used to treat angina do? |
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Definition
1. decrease cardiac o2 demand -> decrease cardiac work
2. increase cardiac o2 supply -> increase vasodilation |
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Term
| What do drugs used to treat angina redress? |
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Definition
the balance between O2 supply and demand
they affect the coronary and systemic vasculature and/or heart |
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Term
| What is the effect of decreasing venous return? |
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Definition
1. decreasing EDV (pre-load)
2. decrease wall stress and work (therefore O2 demand)
3. increase sub-endo O2 perfusion |
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Term
| What is the effect of decreasing peripheral resistance? |
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Definition
(decreases afterload)
decreases work and therefore O2 demand |
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Term
| What is the effect of decreasing rate and force of contraction? |
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Definition
1. decrease work and therefore O2 demand
2. increase O2 perfusion during diastole |
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Term
| What is the effect of coronary vasodilation in collaterals? |
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Definition
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Term
| Why does increased HR not improve O2 to the myocardium? |
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Definition
| less time spent in diastole |
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Term
| Which angina drug is the only one that cannot be used to treat all types of angina? |
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Definition
| beta blockers cannot treat Prinzmental angina |
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Term
| What drugs are used to treat angina |
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Definition
1. nitrates
2. calcium channel blockers
3. beta blockers
4. potassium channel activators |
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Term
| What nitrate treatment is there for less than 2 attacks a week? |
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Definition
Glyceryl trinitrate (nitroglycerin)
- short acting, sublingual (tablet) or aerosol spray (for treatment) |
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Term
| What nitrate treatment is there for more than 2 attacks a week? |
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Definition
isosorbide mononitrate
- long lasting, oral (for prevention) |
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Term
| Adverse effects of nitrates |
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Definition
- headache
- flushing: to become markedly red in the face (blushing is much milder)
- postural hypotension
- tolerance development |
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Term
| What are the effects of nitrates? |
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Definition
POTENT SYSTEMIC AND CORONARY VASODILATORS
- decrease peripheral resistance (afterload)
- coronary vasodilation of collaterals
- decrease venous return
- decreased EDV (pre-load) |
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Term
| Describe the mechanism of nitrates |
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Definition
In vascular smooth muscle:
1. Nitrates are metabolised and produce NO. NO activates soluble guanylate cyclase
2. increased cGMP formation
3. activates PKG
4. dephosphorylation of myosin light chains
5. removal of intracellular Ca2+ and conesquent relaxation |
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Term
| When is the contractile machinery of smooth muscle activated? what causes relaxation? |
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Definition
- when the myosin light chain undergoes phosphorylation
- becomes detached from actin filaments
- catalysed by MLCK
- MLCK is activated when bound to Ca2+ via calmodulin
- myosin phosphatase reverses phosphorylation and causes relaxation |
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Term
| How care voltage-dependent Ca2+ channels inactivated via nitrates? |
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Definition
| NO eventually causes the activation of PKG which activates K+ channels. Movement of K+ out of the cell hyperpolarises the membrane and inactivates voltage dependent Ca2+ channels. |
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Term
| What do drugs that activate K+ channels cause? |
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Definition
| vasodilation via the K+ channels and NO |
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Term
| How does NO cause relaxation? |
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Definition
1. NO activates soluble guanylate cyclase
2. increased cGMP formation
3. activates PKG
4. dephosphorylation of myosin light chains
5. removal of intracellular Ca2+ and conesquent relaxation |
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Term
| What has the same mechanism as activation of K+ channels? |
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Definition
nitrates
they work simultaneously |
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Term
| Give an example of a K+ channel activator |
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Definition
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Term
| What are the adverse effects of nicorandil? |
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Definition
| headache, flushing and dizziness |
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Term
| How are Ca2+ channel blockers administered? |
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Definition
prophalactically
(varied effects) |
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Term
| What types of Ca2+ channel blockers are there? |
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Definition
- cardiac selective
- vascular selective |
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Term
| How do cardiac selective Ca2+ channel blockers work? give an example |
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Definition
decrease rate and force of contraction on heart
verapamil |
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Term
| How do vascular selective Ca2+ channel blockers work? give an example |
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Definition
decrease peripheral resistance (afterload)
increase coronary vasodilation
decrease venous return and therefore decrease EV
nifedipine |
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Term
| Describe the Ca2+ channel blocker mechanism |
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Definition
1. block calcium entering vascular SMC
2. Ca2+ does not bind to calmodulin
3. MLCK not activated
4. myosin not phosphorylated therefore cannot interact with actin |
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Term
| Adverse effects of Ca2+ channel blockers |
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Definition
- headache
- flushing
- ankle swelling
- heart block
- worsen heart failure |
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Term
| What is the effect of beta blockers? |
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Definition
| reduce effects of sympathetic stimulation of the heart |
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Term
| Which form of angina do beta blockers not treat? |
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Definition
| Prinzmentals angina because they exaserbate the spasm of the coronary artery |
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Term
| Adverse effects of beta blockers? |
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Definition
- fatigue
- headache
- sleep disturbances
- sudden withdrawal may exaserbate angina |
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Term
| What are additional treatments for unstable angina? |
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Definition
- antiplatelet (aspirin)
- anticoagulant (heparin/warfarin)
- revascularisation |
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Term
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Definition
statins (atherosclerosis)
ACE inhibitors (vasodilation, antithrombotic, antiproliferative) |
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