Ischaemic heart disease Flashcards
Definition and risk factors
inadequate blood flow to the heart: e.g., angina, myocardial infarction, can be due to thromboembolic occlusion in the coronary arteries.
Male, family history, smoking, diabetes, hypercholesterolaemia, hypertension, sedentary lifestyle, obesity.
Angina non-pharmacological managements
stop smoking, exercise, diet, weight
can be stable or unstable.
Coronary artery bypass surgery
percutaneous transluminal coronary angioplasty and stenting (to open up the coronary artery)
Nitrates for angina
e.g., glyceryl trinitrate (NO donor)
increases [NO] to activate soluble RGC. causes venodilatation (decreases preload and cardiac work needed), and coronary vasodilatation.
GTN is metabolised by aldehyde dehydrogenase into NO.
Can develop tolerence, due to reduced conversion by aldehyde dehydrogenase, or heightened inactivation by superoxide.
Can cause headaches and postural hypotension.
B-blockers
e.g., propranolol, atenolol
Inhibits the B-AR mediated closing of K+ channels - heightened hyperpolarisation - longer period before SA node fires.
First choice for angina. decreases HR (primarily extending diastolic period, increasing time for blood to reach the cardiac muscles) anddecreases contractile force.
Calcium channel blockers for angina
e.g., dihydropyridines (nifedipine) to vasodilate
Verapamil reduces HR and cardiac load - muscles need less blood for function
ACEIs for angina
vasodilatory effect to reduce heart workload. also reduces MI and stroke.
K+ channel activators for angina
nicorandil activates KATP channels in smooth muscle, to increase hyper polarisation - relaxation/vasodilation -> reduced BP
Also a NO donor - vasodilation
Ivabradine mechanism
inhibits the If channel (the pacemaker Na/K channel in SA node).
The If channel is HCN (hyper polarisation-activated cyclic nucleotide gated). hyperpolarization of it produces cylcic AMP leading to hr and contractile force increases
Blocking this channel reduces heart rate by slowing the rate of depolarisation before AP fires.
Enters channel form the inside when in opened state
Antiplatelts for IHD
Inhibits the platelet aggregation that can cause blood clots which would inhibit blood flow through the coronary artery.
Myocardial infarction definition, mechanism, symptoms and diagnosis
Thromboembolism, or plaque that ruptures. Blocks the blood flow through vessel.
Pain, breathlessness, anxiety, nausea, sweating, tachycardia, etc… Can be silent though
Test cardiac enzymes: troponin T will be released into the blood, creatine kinase, aspartate, aminotransferase, and lactate dehydrogenase
myocardial infarction treatment
Thrombolyitcs/fibrinolytics convert plasminogen to plasmin, which dissolves the fibrin clots.
Once treated, antiplatelets, beta blockers, ACEIs and statins may be used to reduce the risk of further issues
