SIHD & Angina - Therapy Flashcards
What does SIHD stand for?
Stable ischaemic heart disease
What are acute coronary syndromes?
Sets of signs and symptoms due to decreased blood flow in the coronary arteries
What are some acute coronary syndromes?
Myocardial infarction
Unstable angina pectoris (angina which is irregular)
What are the 2 kinds of myocardial infarction?
STEMI
NSTEMI
What is stable coronary artery disease?
Set of signs and symptoms due to recurrent, tansient spisodes of chest pain representing demand-supply mismatch
What are examples of stable coronary artery disease?
Angina pectoris
Silent ischaemia
What is angina pectoris?
Chest pain due to coronary heart disease
What is chest pain due to coronary heart disease called?
Angina pectoris
What is silent ischaemia?
Ischaemic episodes with no symptoms so the patient is unaware
What are ischaemic episodes with no symptoms so the patient is unaware called?
Silent ischaemia
What are risk factors for stable coronary artery disease?
Hypertension
Smoking
Hyperlipidaemia
Hyperglycaemia
Male
Post-menopausal female
Are males or females more at risk of stable coronary artery disease?
Males
What does stable coronary artery disease arise due to?
Mismatch between myocardial blood/oxygen supply and demand
What does SCAD stand for?
Stable coronary artery disease
What may attacks of angina due to stable coronary artery disease be precipitated by?
Any stress which increases cardiac work and myocardial oxygen demand
What are the 2 kinds of ischaemia?
Demand ischaemia
Supply ischaemia
When does demand ischaemia occur?
During stress (physical/emotional)
When does supply ischaemia occur?
At rest
What are some determinants of demand ischaemia?
Heart rate
Systolic blood pressure
Myocardial wall stress
Myocardial contractility
What are some determinants of supply ischaemia?
Coronary artery diameter and tone
Collateral blood flow
Perfusion pressure
Heart rate (duration of diastole)
What is hyperlipidaemia a disease of?
Muscular arteries (not veins)
What is the process of hyperlipidaemia leading to atherosclerosis?
1) Progressive depositions of cholesterol esters
2) Lesions start as fatty streaks
3) Develop into fibrous plaque
What does ischaemic heart disease lead to?
Myocardial infarction
What does cerebrovascular disease lead to?
Stroke
What are the fatty streaks that lesions start as composed of?
Sub endothelial accumulation of large foam cells (derived from macrophages plus smooth muscle cells) filled with lipid
How does fibrous plaque reduce blood flow?
Projects into the lumen of the vessel
Where in the blood vessel are most of the changes during atherosclerosis?
In the intimal layer
What is a fibrous plaque composed of?
Fibrous cap
Necrotic core
What is the common pathology of stable ischaemic heart disease?
Atherosclerosis
What does therapy of stable ischaemic heart disease target?
Atherosclerosis
What treatment can help correct the imbalance of supply and demand?
Drug treatment
How can drug treatment help to correct the imbalance between supply and demand?
Decreasing the myocardial oxygen demand by reducing cardiac workload
Increasing the supply of oxygen to ischaemic myocardium
How can drugs reduce the cardiac workload?
Reduce heart rate
Reduce myocardial contractility
Reduce afterload
What is the purpose of drug treatment for stable ischaemic heart disease?
Relieve symptoms
Halt the disease process
Regression of the disease process
Prevent myocardial infarction
Prevent death
What are examples of different drug therapies for angina?
Beta-adrenoceptor antagonists (rate limiting)
Ivabradine (rate limiting)
Calcium channel blockers (rate limiting)
Calcium channel blockers (vasodilators)
Nitrates (vasodilators)
Potassium channel openers
Aspirin/clopidogrel/tigagrelor
Cholesterol lowering agents
What are examples of cholesterol lowering agents?
HMG CoA reductase inhibitors
Fibrates
What are examples of drugs that improve the supply of blood to the heart?
Vasodilators such as nitrates and calcium channel blockers
What are examples of drugs that reduce the demand of the heart?
Rate limiting drugs such as beta blockers and calcium channel blockers
What are examples of beta blockers?
Bisoprolol
Atenolol
What are beta blockers?
Reversible antagonists of the B1 and B2 receptors
What 3 major determinants of myocardial oxygen demand do beta blockers decrease
Heart rate
Contractility
Systolic wall tension
What do beta blockers allow greater perfusion of?
Subendocardium by increasing diastolic perfusion time
How do beta blockers increase diastolic perfusion time?
Decrease the heart rate
Decrease the force of myocardial contraction
Decrease cardiac output
Decrease velocity of contraction
Decrease blood pressure
Protect cardiomyocytes from oxygen free radicals formed during ischaemic episodes
How do beta blockers change the relationship between exercise and angina?
Increase the exercise threshold at which angina occurs
What is a concern for beta blockers?
Rebound phenomena
What is beta blockers rebound phenomena?
Sudden cessation of beta blocker therapy may precipitate myocardial infarction
Who is at risk of beta blocker rebound phenomena?
Patients with angina and men over 50 years recieving beta blockers for other reasons
What are some contraindications for beta blockers?
Asthma
Peripheral vascular disease (and relative contraindications)
Raynauds syndrome
Heart failure (patients are dependent on sympathetic drive)
Bradycardia/heart block
What are some adverse drug reactions with beta blockers?
Tiredness/fatigue
Lethargy
Impotence
Bradycardia
Bronchospasm
What is lethargy?
Lack of energy and enthusiasm
What is lack of energy and enthusiasm?
Lethargy
What are sime drug-drug interactions with beta blockers?
Hypotension with other hypotensive agents
Bradycardia when used with other rate limiting drugs
Cardiac failure when used with negatively inotropic agents
NSAIDS antagonise antihypertensive actions
Exaggerate and mask hypoglycaemic actions of insulin or oral hypoglycaemics
What are examples of rate limiting drugs other than beta blockers?
Verapamil
Diltiazem
What are examples of negatively inotropic agents?
Verapamil
Diltiazem
Disopyramide
What are examples of calcium channel blockers?
Diltiazem
Verapamil
Amlodipine
How do calcium channel blockers work?
Prevent calcium influx into myocytes and smooth muscle lining arteries and arterioles by blocking the L-type calcium channel
What are the 2 types of calcium channel blockers?
Rate limiting
Vasodilating
How do rate limiting calcium channel blockers work?
Reduced heart rate and force of contraction
How do vasodilating calcium channel blockers work?
Produce a reflex tachycardia
What are examples of rate limiting calcium channel blockers?
Diltiazem
Verapamil
What are examples of vasodilating calcium channel blockers?
Nifedipine
Amlodipine
What does CCB stand for?
Calcium channel blockers
What are contraindications for calcium channel blockers?
Post myocardial infarction
Unstable angina
Why is post myocardial infarction a contraindication for calcium channel blockers?
May increase morbidity and mortality in patients with impaired liver function
Why is unstable angina a contraindication for calcium channel blockers?
May increase infarction rate and death in the unstable patient
What are some adverse drug reactions of calcium channel blockers?
Oedema
Headache
Flushing
Palpation
What are nitrovasodilators also known as?
Nitrates
What are examples of nitrovasodilators?
Glyceryl trinitrate (GTN)
Isosorbide mononitrate
Isosorbide dinitrate
What does GTN stand for?
Glyceryl trinitrate
How can glyceryl trinitrate (GTN) be given?
Sublinguinal
Buccal
Transdermal
How can isosorbide mononitrate be given?
Sustained release formulation in tablets
How can isosorbide dinitrate be given?
Sustained release formulation in tablets
How do nitrovasodilators work?
Release NO which then stimulates the release of cGMP which produces smooth muscle relaxation, this preduces preload and afterload so reduces the myocardial oxygen consumption
How do nitrovasodilators relieve angina?
Arteriolar dilation and so reducing cardiac afterload and thus myocardial work and oxygen demand
Peripheral venodilation so reducing venous return, cardiac preload and thus cardiac workload
Relieving coronary vasospasm
Redistributing myocardial blood flow to ischaemic areas of the myocardium
What is GTN used for?
Rapid treatment of angina pain
How can GTN avoid first pass metabolism?
Given by the sublinguinal route
How are oral nitrates commonly used?
Once a day sustained release formulation
What are oral nitrates used for?
Prophylaxis
What are intravenous nitrates used for?
Treatment of unstable angina where they are used in combination with heparin
What is intravenous nitrates used with to treat unstable angina?
Heparin
What can develop to the effects of nitrate therapy rapidly?
Tolerance
How can tolerance to nitrate therapy be overcame?
Giving asymmetric doses of nitrate at 8am and 2pm
Using sustained release preparation which incorporates a nitrate free period
What are potential adverse drug reactions of nitrates?
Headaches
Hypotension
What does hypotension due to nitrates lead to?
GTN syncope
How can headaches due to nitrates be avoided?
Increase dose slowly
What are some new approaches to myocardial ischaemia treatment?
Preconditioning
Late sodium current inhibition
Sinus node inhibition
Metabolic modulation
What drug is used for preconditioning?
Nicorandil
What drug is used for late sodium current inhibition?
Ranolazine
What drug is used for sinus node inhibition?
Ivabradine
What drug is used for metabolic modulation?
Trimetazidine
What is preconditioning?
An experimental technique for producing resistance to the loss of blood supply and thus oxygen
How does preconditioning work?
1) Activate ATP sensitive potassium channels
2) Entry of potassium into cardiac myocytes inhibits calcium influx and so had a negative inotropic action (decreases force of speed of contraction of muscles)
What does activation of ATP-sensitive potassium channels in preconditioning cause?
1) Potassium efflux and hyperpolarisation of the smooth muscle membrane and closure of voltage gated calcium channels
2) Closure of calcium gated channels reduces intracellular levels of calcium, resulting in relaxation of vascular smooth muscle and dilation of systemic and coronary arterioles
What is ivabradine?
Selective sinus node If channel inhibitor
What is nicorandil used for?
Preconditioning
What is ivabradine used for?
Sinus node inhibition
How does ivabradine work?
Slows the diastolic depolarisation slope of the SA node which results in reduction in heart rate (so reduces myocardial oxygen demand)
What is randolazine used for?
Inhibit late sodium current
How does ranolazine work?
1) Inhibits persistent or late inward sodium current (INa) in heart muscle in a variety of voltage gated sodium channels
2) Inhibiting that current leads to reduction in intracellular calcium levels, this in tern leads to reduced tension in the heart wall leading to reduced oxygen demand
What are examples of antiplatelet agents?
Low dose aspirin (75-150mg)
Clopidogrel
What is considered to be low dose aspirin?
75-150mg
What is the formation of platelet aggregates important in the pathogenesis of?
Angina
Unstable angina
Acute myocardial infarction
What is aspirin a potent inhibitor of?
Platelet thromboxane production
What does thromboxane do?
Stimulates platelet aggregation and vasoconstriction
Who is low dose aspirin effective in?
Patients with a heart rate greater than 70
What are indications of low dose aspirin?
Adults unable to tolerate or with a contraindication to beta blockers
Or in combination with beta blockers in patients inadequately controlled with an optimal beta blocker dose
How does clopidogrel work?
Inhibits ADP receptor activated platelet aggregation
What are potential side effects of aspirin and clopidogrel?
Bleeding, such as lower GI tract bleeding
What can regular daily use of aspirin do?
Reduce mortality of acute myocardial infarction (by 23%)
Reduce unstable angina leading to myocardial infarction and death (by 50%)
In secondary prevention reduce reinfarction by 32% and combined vascular events by 25%
What are examples of cholesterol lowering agents?
Simvastatin
Pravastatin
Atorvastatin
How do cholesterol lowering agents work?
HMG CoA reductase inhibitors
What does aggressive cholesterol lowering post myocardial infarction reduce?
Cardiovascular mortality by 42% and total mortality by 30%
What are the NICE guidelines for treatment of angina?
1) Beta blockers should be used as first line therapy for the relief of symptoms of stable angina
2) If adequate control of angina not achieved add a calcium channel blocker
3) If still not control consider switching to other options or using a combination of the 2
4) All patients with stable angina due to atherosclerotic disease should recieve longh term standard aspirin and statin therapy
5) All patients with stable angina should be considered for treatment with ACEi
What should all patients with stable angina due to atherosclerotic disease recieve?
Long term standard aspirin and statin therapy
What are some drugs for secondary prevention of cardiovascular disease?
Aspirin 75mg daily
ACE inhibitors for people with stable angina and diabetes
Statin treatment
Treatment for high blood pressure
What drugs should people with stable angina and diabetes recieve?
ACE inhibitors