SIHD and Angina - Therapy Flashcards
Define acute coronary syndromes (ACS)
- AMI
- Unstable angina pectoris
Name the medication used to treat angina
Rate-limiting;
- Beta-adrenoreceptor antagonists
- Ivabridine
- CCB
Vasodilators;
- CCB
- Nitrates (oral, sublingual)
Others;
- Potassium channel openers
- Aspirin/clopidogrel/tigragelor (platelet aggregation inhibitors)
- Cholesterol lowering agents: MHA CoA reductase inhibitors, fibrates
Define supply ischaemia
Ischaemia at rest.
- Coronary artery diameter and tone
- Collateral blood flow
- Perfusion pressure
- HR (duration of diastole)
Describe the ways drugs can decrease myocardial demand for oxygen (i.e. treatment for angina)
- Decrease HR
- Decrease myocardial contractility
- Reduce afterload
Define demand ischaemia
Ischaemia during stress.
- HR
- Systolic BP
- Myocardial wall stress/contractility
Treat with beta blockers, CCB.
Define supply ischaemia
Ischaemia at rest.
- Coronary artery diameter and tone
- Collateral blood flow
- Perfusion pressure
- HR (duration of diastole)
Treat with nitrates, CCB.
Define beta blockers
- Reversible antagonists
- Can be cardioselective (only act on beta-1 receptors)
- Block sympathetic system
- Decrease HR, contractility and wall tension
- Improve perfusion of subendocardium by increase duration of diastole
Define beta blockers
- Reversible antagonists
- Can be cardioselective (only act on beta-1 receptors)
- Block sympathetic system
- Decrease HR, contractility and wall tension
- Decrease CO, BP
- Improve perfusion of subendocardium by increase duration of diastole
- Protect cardiomyocytes from oxygen free radicals formed during ischaemic episodes
- Can increase exercise threshold
Define rebound phenomena
Sudden cessation of beta blockers can cause MI.
Define the contraindications of beta blockers
- Asthma
- Peripheral vascular disease
- Raynauds syndrome
- Heart failure: dependent on sympathetic drive
- Bradycardia/heart block
Define the adverse drug reactions of beta blockers
- Fatigue/lethargy
- Impotence
- Bronchospasm
- Bradycardia
Define the drug-drug interactions of beta blockers
- Hypotension with other hypotensive agents
- Bradycardia with other rate-limiting drugs
- Cardiac failure with other negative inotropic agent
- Exaggerate/mask hypoglycaemic drugs
Define CCBs
- Rate-limiting: reduce HR, contraction
- Vasodilators: may produce reflex tachycardia
- Reduce tone –> vasodilation –> reduce afterload
Define the contraindications of CCBs
- Vasodilators: may cause AMI or stroke
- Post-MI: may impair LV function
- Unstable angina: may increase MI, death
Define the adverse drug reactions of CCBs
- Ankle oedema
- Headache
- Flushing
- Palpitations
Define nitrovasodilators (GTN, oral, IV)
- Relax almost all smooth muscle
- Arterial vasodilation: reduce afterload
- Peripheral ventilation: reduce VR, preload
- Relieve coronary vasospasm
- Redistribute myocardial blood flow
Define tolerance of nitrovasodilators
- Can become tolerated quickly
- Treat by giving asymmetric doses of nitrate
Define the adverse drug reactions of nitrovasdilators
- Headaches
- Hypotension
Define the new approach medications to angina
- Metabolic modulation
- Sinus node modulation
- Late Na+ current inhibition
Define nicorandil
- Activate ATP-sensitive K+ channels
- Entry of K+ inhibits Na+ influx –> negative inotropic action
- Ischaemic preconditioning –> cardioprotective effect
Define ivabridine
- Sinus node inhibitor (rate-limiting)
- Slows diastolic depolarisation, reduces HR
Define ranolazine
- Late Na+ current inhibiton
- Reduced wall tension
Define anti-platelet agents
Low dose aspirin (75-150mg);
- Inhibits thromboxane production: platelet aggregation and vasoconstriction
- Only reduces CAD outcome if HR >70bpm
- Use for people who can’t’ take beta blockers
- Or in combo with BB if it isn’t that effective
- Most common cause of admission with GI bleed
Define clopidogrel
- Inhibits ADP receptor-activated platelet aggregation
- Prevents atherosclerotic events in PVD
- Treat ACS
- Same incidence of bleeding as aspirin
Define the treatment regimen for angina
- Beta blocker
- Rate-limiting CCB
- Dihydropiridine CCB (vasodilator, long-acting)
- Ivabridine (sinus node inhibitor)/Ranolazine (late Na+ current inhibitor)
- Aspirin (anti-platelet)
- Statin (cholesterol-lowering agent)
- Long acting nitrate
- Nicorandil (K+ channel opener)
- Refer to cardiology
