Pharmacology of the CVS Flashcards
Quantitatively describe the effects of angina pectoris
- 2 million sufferers in the UK
- annual risk of death (usually MI) of 4 - 6%
- Quality of life impacted
What causes angina pectoris?
Caused by local myocardial Ischaemia
- when oxygen demand exceeds supply
- often precipitated by exertion; reversible at rest
Outline the symptoms of Angina Pectoris
- Crushing chest pain (or in jaw, shoulders ,arms)
- Ischaemic products (H+, lactate)
-> stimulate nociceptive afferents - may be associated with shortness of breath, sweating
and nausea
What is the risk of angina increased by?
Increased Systolic BP (afterload)
Increased sympathetic nerve activity
Increased Contractility
Increased vasoconstriction
Explain how increased afterload increases risk of angina
Heart has to work harder to eject blood; requires more oxygen
How does increased sympathetic activity cause angina?
Less diastolic time
Less coronary artery perfusion which only occurs in systole
What causes increased contractility?
exercise
emotion
stress
aortic valve stenosis
=> all increase Oxygen demand
Give an example of how increased vasoconstriction trigger angina?
e. g.
- Redistribution of blood flow in cold weather
- During large meal blood diverted to GI
etc.
=> vasoconstriction in coronary circulation
What are the different types of angina?
Stable Angina
Unstable Angina
Variant (prinzmetal) Angina
Describe the pathology of Stable angina
most common form
- exercise induced: predictable can work out how much
exertion induces symptoms
- not able to meet increased oxygen demand due to
atheroma in coronary arteries - relieved by rest and medications
Describe unstable angina
- induced due to minimal exertion; unpredictable
- rest and medications may not relieve symptoms
- may indicate thrombosis / plaque rupture
Outline the features of Variant (prinzmetal) angina
- symptoms at rest
- decreased oxygen supply due to vasospasm
(uncontrolled vasoconstriction decreasing blood flow)
downstream of occlusion
How are the different forms of angina detected?
All linked to acute coronary syndrome (coronary thrombosis)
- ECG will show STEMI
Describe the effect of stable angina during normal activity
In exercise, metabolic vasodilation of arterioles reduces resistance to increase blood flow to meet increased oxygen demand
Describe the effects of stable angina during exercise
Stenosis in coronary arteries increases resistance
at rest metabolic vasodilation occurs as normal
However/
during exercise arterioles may attempt further dilation but TPR is still too high - Oxygen demand can’t be met; angina develops
What are the aims of angina treatment?
Improve prognosis
- prevent MI + death
- reduce plaque progression - stabilise it
- prevent thrombosis
Minimise symptoms
- improve quality of life
What are the approaches to angina treatment?
Vasodilators: Nitrates
Cardiac depressants: Beta Blockers
Both: Ca2+ blockers
Explain how ꞵ Blockers aid angina treatment
Reduce action of sympathetic activity (NA and adrenaline) on ꞵ₁ adrenoceptors in the heart causing:
- Slow HR and AV conduction
- Reduced force of Contractility