Angina Flashcards
other names for Stable coronary artery disease
Angina pectoris
Silent ischemia
Risk factors for angina
Hypertension Smoking Hyperlipidemia Hyperglycaemia Male Post menopausal females
Stable coronary artery disease
A result of a mismatch between myocardial blood/oxygen supply and demand
Attacks of angina when stressed/increased demand, anything that increases HR, SV or BP
Determinants of demand
HR
Systolic BP
Myocardial wall stress
Myocardial contractility
Determinants of supply
Coronary artery diameter and tone
Collateral blood flow
Perfusion pressure
Heart rate (duration of diastole)
Types of atherosclerotic lesions
1- adaptive thickening of smooth muscle at lesion prone location
2- macrophage foam cells
3- small pools of extracellular lipid
4- core of extracellular lipid
5- fibrous thickening
6- complicated lesion eg thrombus, fissure and haemotoma
Purpose of drug treatment
Relieve symptoms Halt disease process Regression of disease process Prevent MI Prevent death
Beta blockers
Bisoprolol and atenolol
Reversible antagonists on B1 and (B2) receptors which block sympathetic system
Decrease HR, contractility, systolic wall tension, BP, velocity of contraction
Allow improved perfusion of subendocardium by increasing diastolic perfusion time which protects cardiomyocytes from O2 free radicals during ischaemic episodes
Increase exercise threshold that angina occurs at (demand outstrips supply)
Negative parts of beta blockers
Rebound phenomena- don’t stop suddenly
Contraindications- asthma, PVD, reynauds, HF if dependant on sympathetic drive, bradycardia
Adverse drug reactions- tiredness/fatigue, lethargy, bradycardia, bronchospasm
Drug-drug interactions- don’t use with other hypotensives too much or rate limiting drugs or negatively ionotropic agents, mask hypoglycemia
Calcium channel blockers
Diltiazem, verapimil, amlodipine
Prevent calcium influx into myocytes and smooth muscle around arteries by blocking l-type channels
Rate limiting CCBs
Diltiazem, verapimil
Reduce heart rate and force of contraction (reduce myocardial oxygen requirements)
Vasodilating CCBs
Amlodipine, can cause reflex tachycardia
Contraindications for CCBs
Never use nifedipine immediate release as can cause MI or stroke
Do not use post MI as can increase morbidity and mortality in patients with impaired LV function
Do not use for unstable angina as dihydropyridines (vasodilators) may increase infarction rate and death
Adverse drug reactions for CCBs
Ankle oedema that doesn’t respond to diuretics
Headache
Flushing
Palpitations
Nitrovasodilators
GTN(sublingual) to avoid fpm and also prophylaxis
Isosorbide mono and dinitrate (sustained release) prophylaxis
Relax almost all smooth muscle cells by releasing NO which stimulates release of cGMP
Reduces preload and afterload so reduce myocardial oxygen consumption, relieved coronary vasospasm and redistributes myocardial blood flow to ischemic areas
When are IV nitrates used
Unstable angina, with heparin
Negative parts of nitrates
Tolerance can develop unless asymmetric doses used or incorporating a nitrate free period
Adverse drug reactions- headache so increase dose slowly, hypotension (GTN syncope)
New approaches to myocardial ischemia
Metabolic modulation by trimetazidine
Sinus node inhibition by ivabradine
Late Na current inhibition by ranolazine
Preconditioning by nicorandil