Ischaemic heart disease Flashcards
What is IHD?
Umbrella term-
coronary artery disease /IHD/ coronary heart disease all describe the same condition
occurs when a fatty plaque blocks the coronary artery lumen- ischemia
Whats the progression of coronary atherosclerosis?
foam cells-> fatty streak-> intermediate lesions-> atheroma-> complicated lesion or rupture-> fibrous plaque
What are the risk factors for IHD?
Nonmodifiable- age, male sex, positive family history
Modifiable- high bp, diabetes, smoking, raised cholesterol
What are the acute coronary syndromes?
unstable angina
non-ST elevated myocardial infarction (NSTEMI)
ST elevation myocardial infarction (STEMI)
STEMI= a sudden, complete blockage of the artery
NSTEMI= partial/temporary blockage of the artery
-syndrome presents itself when the plaque ruptures
-stable angina= not an ACS
What is angina?
central crushing pain triggered by exertion- relieved by rest
What is unstable angina and how do you treat it?
Unstable angina- pain occurs with less and less exertion- including at rest
- DAPT
- nitrates
What is stable angina and how do you treat it?
triggered by exertion, goes away with rest
- nitrates
- calcium antagonists
- statins- treat underlying cause
- prophylaxis- antiplatelet drug
ECG and blood features of unstable angina
GTN relief- yes
ECG normal- yes (not normal in an episode)
Troponin raised- no
ECG and blood features of STEMI and NSTEMI
GTN relief- no
ECG normal- no
Troponin raised- yes
troponin raised= indicated dying myocytes
What are the broad aims for the treatment of ischaemia?
Restore blood flow quickly
- reopen blocked arteries
- reduce coagulability of the blood- antiplatlet, aspirin, heparins
- control risk factors- statins etc
- reduce myocardial oxygen demand- ACE-Is and diuretics
What is PCI?
Percutaneous coronary intervention non-surgical technique
insert a catheter into the radial/brachial artery- track the catheter under fluoroscopic guidance into the coronaries- widens the artery from within
use of a stent with a balloon
What sort of drugs are normally attached to the stent?
Drug coated- inhibit cell regrowth
rapamycin or taxol
Why is stenting bespoke?
Using angiograms- can see the coronary arteries- see where the stent needs to go
What drugs need to be taken after stenting?
Dual action antiplatelet therapy clopidogrel or ticagrelor -continue for a year after stenting -adverse effects- risk of bleeding benefits: anti-inflammatory- not understood
What are symptomatic treatments- give examples
Reduce the symptoms
-reduce strain on the heart- increase vasodilation
nitrates (glyceryl nitrate - short-acting) (isosorbide mononitrate- long lasting)
aspirin and antiplatelet drugs
Ca channel blockers- amlodipine
K channel activators- nicorandil
analgesia- morphine
What are prognostic treatments- give examples
Alleviate further negative outcomes aspirin statins/ pcsk9 inhibitors beta blockers ACE inhibitors anti-inflammation approaches being developed
Nitrates- primary and secondary mechanisms
First line agent= GTN (nitroglycerin)
primary mechanism: relax smooth muscle & the veins- main effect on the larger muscular arteries and coronary vasodilation
secondary mechanism: reduce cardiac work, redirection of flow towards ischaemic areas of heart muscle, improves coronary artery spasm
*mechanism- GTN metabolism releases NO- activates GC- increased cGMP- leads to smooth muscle relaxation
What are the adverse effects of nitrates, and what are their pharmacokinetic features
Possibly hypotension
headaches
tolerance can occur
-GTN is inactivated by hepatic metabolism
-length of effect= 30 minutes
-isosorbide mononitrate- orally administered 2 x a day- nitrate free period at night to avoid tolerance
Features of calcium channel blockers and their pharmacokinetics
Reduce ischaemia but not mortality
non-selectively blocks contraction of smooth muscle
-verapamil selective to the heart- nifedipine more selective to smooth muscle
-few sides fx: flushing and headache due to vasodilation
-amlodipine has a long elimination time
How does aspirin work?
Reduces mortality and risk of future heart attack
inhibits COX1 receptors on platelets- reduces platelet aggregation
irreversibly acetylates cox enzymes
prevents conversion of arachidonic acid to thromboxane 2
aspirin can last as long as 10 days- how long it takes for platelets to replenish
Risk- GI bleeding
What are the pharmacokinetics of aspirin?
given orally
weak acid
ileum is site of absorption
side fx: gastric bleeding, deafness/ tinnitus (larger/ over doses)
risk of self-poisoning
some are resistant- no genetic test available yet
interacts with warfarin- increases conc of warfarin- effects platelets
How do anticoagulants/ anti-platelet approaches work?
Inhibit clotting factors in the clotting cascade
heparins: enoxaparin- activates antithrombin 3a which inactivates thrombin and factor Xa- prevent formation of a stable clot
side fx: bleeding
anti-platelet approach: clopidogrel
What analgesics are given in ACS?
opiates and antiematics
morphine= usually well tolerated if given correctly
side fx: nausea/ vomiting
What are the treatments for unstable angina?
DAPT heparins analgesics secondary prevention: statins, ace inhibitors or beta blockers once stabilized: elective (planned) PCI
What are the treatments for NSTEMI?
Antiplatelet and antithrombotic therapy
analgesics
PCI within 72 hrs to determine lesions severity and suitability for stenting or a bypass
What are the treatments for STEMI?
Primary PCI at local heart attack centre
if unable- use a clot busting drug intravenously
antiplatelet medications
life long medications:
aspirin, antiplatelet, ACE-Is, beta blockers to aid myocardial recovery
Examples of IHD personalisation
- Measure individual platelet reactivity
- Angiograms- individualized map of coronary arteries
- can use computer modelling to do this- different angles and branches and sites of lesions - Anti-inflammatory approach- future potential treatment- been proven that inhibition of inflammation prevents repeat heart attacks and reduces all cause mortality
