Pharmacological Treatment Of Angina Flashcards
Where does the pain come from in angina?
Heart muscle- caused by the lactic acid produced during anaerobic respiration
Stimulated myocardial pain receptors which send messages via cardiac nerves and upper posterior nerve routes to the brain
What are the symptoms of angina?
- Feeling of cramping and severe constriction in the chest
- referred pain- jaw, shoulders, neck and arms
- may be associated with shortness of breath, sweating and nausea
What are the key facts of chronic stable angina?
Affects around 2-4% of the population in western countries
Associated with estimated annual risk of death of 1-2%
Estimate that 1.3 million people in the UK are living with angina
What are the treatment aims of angina?
To enhance quality of life through reduction of symptoms
To improve prognosis and prevent complications
Well tolerated and they cause minimal side effects
What are the four types of angina?
Stable, unstable, prinzmetal and micro vascular
What are the causes of stable angina?
Attributed to myocardial ischaemia
What causes unstable angina?
Complications from stable angina
What causes prinzmetal angina?
Spasm in coronary arteries
What causes coronary vasospasms?
Cocaine use
What is stable angina caused by?
Narrow artery lumen -> restricted blood flow to the area of myocardium it supplies-> oxygen it receives is insufficient when the heat has to work harder-> anaerobic respiration -> pain
How is stable angina relieved?
Rest or taking medication
What’s the difference between stable and unstable angina?
Stable follows a set pattern, unstables predictable
Stable is relieved by rest and medication and unstable isnt
What causes unstable angina?
Clot formation occluded artery-> critical reduction in blood flow so oxygen supply is inadequate even at rest
When does prinzmetal angina occur?
At rest or through the night
How long does prinzmetal angina last?
5-15 mins
How common is prinzmetal angina?
Rare (1 in 100)
What are associated symptoms of prinzmetal angina?
Heartburn, nausea, sweating, dizziness, palpitations, migraines
What causes microvascular angina?
Impaired coronary circulation due to coronary microvascular dysfunction from abnormal vasodilation or increased vasoconstriction
Why can microvascular angina not be diagnosed early?
Coronary microvasculature cannot be directly imaged in vivo
What can be used to asses coronary microvascular blood flow?
PET scan or cardiac magnetic resonance
What is the definition of angina?
An imbalance between demand and supply of oxygen to the heart
What two types of angina cause decreased coronary blood flow?
Vasospasm (prinzmetal) and thrombus blockage (unstable)
What type of angina causes an increased oxygen requirement?
Fixed stenosis (chronic stable angina)
What are the three precipitating factors of angina?
Increased sympathetic activity, contractility and vasoconstriction
What are the three strategies of treating angina?
Improving perfusion, reducing metabolic demand and prevention
What type of drugs improve perfusion?
Coronary vasodilation
How do coronary vasodilators help with angina?
They increase oxygen delivery by improving the coronary blood flow
What types of drugs reduce metabolic demand?
Vasodilators and cardiac depressants
How does reducing the metabolic demand help the treatment of angina?
Reduce oxygen demand by decreasing cardiac work
What types of drugs help in the prevention of angina?
Lipid lowering drugs
Anti-coagulants
Fibrinolytic
Antiplatelet
How does the prevention of angina help?
Prophylactic to reduce the risk of subsequent episodes
Give examples of anti anginal nitrates
Glyceryl trinitrates, isosorbide mononitrate effects
What two ways do nitrates help in angina?
Peripheral venodilation and arterial dilation
How does peripheral venodilation help treat angina?
Peripheral venodilation-> decreases intraventricular pressure -> decreases cardiac preload
How does arterial dilation help treat angina?
Decrease TPR-> reduces afterload
How do nitrates work against angina?
Lower oxygen demands by lowering the work of the heart
What are the adverts effects of using nitrates to treat angina?
- throbbing headache, flushing and syncope
- postural hypotension
- reflex tachycardia
What is the mechanism of action for nitrates in the treatment of angina?
Organic nitrates mimic the effects of endogenous nitric oxide
What do nitric oxide donors cause?
Dilation of smooth muscle
How does PKG reduce smooth muscle tone?
- myosin light chain dephosphorylation
- increased uptake of calcium by SR causing a decrease in cytoplasmic levels
- activate k+ channels causing hyperpolarisation and closing VGCC
What are examples of beta blockers?
Atenolol, bidprolol
What are the effects of beta blockers?
- Inhibits the If pacemaker current in the SA node -> decreases heart rate
- reduce the force of cardiac contractions ->improves exercise tolerance
How do beta blockers help in the treatment of angina?
Reduce cardiac output and blood pressure
What are the adverse effects of beta blockers?
Bronchospasm
Fatigue
Postural hypotension
What is the mechanism of action of beta blockers?
Reduces the sympathetic action of noradrenaline on beta 1 adrenoreceptors on the heart
What are the three types of calcium channel blockers?
Dihydropyridines
Benzothiazepines
Diphenylalkyamines
Give examples of dihydropyridines
Amplodipine
Nifedipine
Give examples of benzothizapines
Verpam
Give examples of diohenylalkyamines
Diltiazem
What are the effects of calcium channel blockers?
- reduce calcium ion entry into cardiac myocytes/smooth muscle cells-> reducing contractility
- direct coronary vasodilation -> more coronary blood flow
- reduce TPR -> Heart works less hard to eject blood
- reduce force of contraction -> less o2 consumption
What are the adverse effects of calcium channel blockers?
- lower limb oedema
- flushing and headaches
- reflex tachycardia
Why do you take caution with calcium channel blockers?
They block calcium channels in the heart that may alter the electrical conduction and contractility
What is the mechanism of action of the calcium channel blockers?
Reduce calcium ion influx through voltage gated L-type calcium channels in smooth and cardiac muscles
What are the three types of prophylactic angina drugs?
Aspirin, clopidogrel and statins
How does aspirin work?
Inhibits COX, decreases thromboxane A2 and platelet aggregation
How does clopidogrel work?
Inhibits ADP receptor on platelets, reduces aggregation
How do statins work?
HMG CoA reductase inhibitor, decreases cholesterol levels
What are the other types of anti anginals?
Nicorandil, ivabradine, ranzolazine
How does nicorandil work?
Potassium channel activator leads to hyperpolarisation
