Angina Pectoris Flashcards
What causes angina?
Myocardial ischaemia, mostly caused by atheroma
What is stable angina?
Induced by exercise/exertion - relieved by rest
What is unstable angina?
Increased frequency or severity; occurs on minimal exertion - associated with increased MI risk
What is angina decubitus?
Precipitated by lying flat
What is variant (aka Prinzmetal’s) angina?
Due to coronary artery spasm
What are sign/symptoms of angina?
Central chest tightness/heaviness brough on by exertion and received by rest
May radiate to neck, jaw, arms and teeth
Can also be precipitated by emotion, cold, weather and heavy meals
Associated with dyspnoea, nausea, sweatiness, faintness
Which investigations would be done?
ECG - usually normal but may show ST depression; flat or inverted T waves
Thallium scan
Cardiac CT
Coronary angiography
How do you treat stable angina?
Beta-blocker
CCB
GTN
Potassium channel opener (Nicorandil)
What is the mechanism of a GTN?
Relax all types of smooth muscle via their metabolism to nitric oxide
Small doses of GTN lead to?
venorelaxation
Decreased preload & SV
Higher doses of GTN cause?
Decreased MAP
Decreased afterload
What is the effect of a GTN?
Coronary blood flow is redirected to ischaemic zone (collateral arterioles dilated)
Decrease myocardial O2 requirement
Decrease after load
Increase ischaemic perfusion
How is a GTN administered?
Sublingual
Why are GTNs not given orally?
First pass metbaolism
What are side effects of GTN?
Repeated admin associated tolerance
Postural hypotension
headaches
How can repeated administration tolerance be avoided?
Build in nitrate low periods
E.g. Take it in the morning and afternoon but not at night
What is the mechanism of a potassium channel opener?
Open vascular smooth muscle ATP-modulated K channels by antagonising intracellular ATP
Hyperpolarisation
Switch off L-type Ca channels
Nicorandil predominantly acts on?
Arteriolar smooth muscle
What are side effects of nicorandil?
Nausea Vomiting rectal bleeding Cutaneous vasodilation - flushing Increase HR (@high doses) Dizziness Headache (esp. on initiation, usually transitory) Weakness
How do you treat angina decubitus (unstable angina)? (medication)
Aspirin IV heparin (or IV GTN)
What is heparin?
Naturally occurring sulphated glycosaminoglycan of variable molecular size
How does antithrombin III neutralise all serine protease factor in the coagulation cascade?
By binding to their active site
What is heparin’s mechanism of action?
Binds to ATIII increasing its affinity for serine protease factors to increase their activation
How is heparin administered?
IV/SC
What is required to determine the dose of heparin?
In vitro clotting test
What are side effects of heparin?
Haemorrhage
Osteoporosis (long-term treatment)
Hypo-aldosteronism
Hypersensitivity reactions
What can reverse heparin?
Protamine sulfate IV
CABG is recommended for angina patient with?
Three-vessel or left main coronary artery disease
PCI is indicated in?
Severe / high risk angina
How is Variant (Prinzmetal’s) angina treated?
CCB + Long acting nitrate
What is an example of a long-acting nitrate?
Isosorbide Mononitrate
What is isosorbide mononitrate used for?
Prophylaxis for angina attack and more sustained effect
not for acute relief
The side effects of isosorbide mononitrate are the same as for?
GTN
