Pharmacology of CVS - Angina Flashcards
What is angina?
→ Angina is chest pain or pressure when there is a build up of lactic acid during anaerobic respiration
→ due to not enough blood flow to the heart muscle.
Signal via cardiac nerves and upper posterior nerve roots
What are the symptoms of angina pectoris?
→crushing chest pain, also in the jaw, shoulders, arms, etc.
→shortness of breath
→sweating
→ nausea
How many people suffer from angina pectoris in the UK and what is the prevelance?
→2 million sufferers in the UK
2-4% of Western countries
What are the symptoms of typical angina?
→ typical angina
→ substernal chest discomfort of characteristic quality + duration
→provoked by exertion or emotional stress
→symptoms attributed to myocardial ischemia
→short duration radiation to left arm, neck, jaw. Lasts 2-5 minutes
How can typical angina be relieved?
→ rest + medications
Why is stable angina classified as predictable?
→ recurrent episodes have a similar onset pattern, duration + intensity
What does a coronary spasm lead to? (Prinzmetal angina)
Caused by drugs like cocaine.
→ Critical reduction in blood flow so oxygen supply is inadequate
What is supply ischaemia?
→ When there is decreased coronary blood flow due to vasospasm or a thrombus / blockage
What is demand ischaemia?
→Increased demand for oxygen in the heart muscle
→ Due to fixed stenosis
What are precipitating factors for angina?
→ Increased sympathetic activity
→ Increased contractility - exercise, emotion or stress
→ Increased vasoconstriction
What are the three ways to treat angina?
→ Improving perfusion
→ Reducing metabolic demand
→ Prevention
How do you improve perfusion with angina?
→ Increase oxygen delivery by improving coronary blood flow
→ coronary vasodilators
How do you reduce metabolic demand with angina?
→ Decrease cardiac work
→ Using vasodilators ( reduce afterload + preload)
→ Using cardiac depressants ( reduce HR + contractility)
How do you prevent angina?
→ Prophylactic to reduce risk of episodes → lipid lowering → anti-coagulants → Fibrinolytic →anti-platelet
What does clot formation lead to? (unstable angina)
→ Occludes the artery
→ There is a critical reduction in blood flow so oxygen supply is inadequate even at rest
What does a narrowed coronary artery lumen lead to? (stable angina)
→ Restricted blood flow to area of the myocardium it supplies
→ Oxygen is receives is insufficient when the heart has to work harder
→ Anaerobic respiration
→Pain
How is preload reduced by giving nitrates?
→ Peripheral venodilation
→ Decreases intraventricular pressure
→ Cardiac preload decreases
→reduced oxygen demand by decreasing the work of the heart
How is afterload reduced by giving nitrates?
→ Arterial dilation
→ Decreases total TPR
→ Reduces afterload
→reduced oxygen demand
What are adverse effects of nitrates and why?
→ Headache, flushing, syncope ( arterial dilation)
→ Postural hypotension ( venodilation)
→ Reflex tachycardia ( sympathetic outflow)
How does nitric oxide work?
→NO synthase makes NO from L-arginine
→ NO activates guanylyl cyclase
→ It activates cGMP
→ Activates protein kinase G
→cGMP converted to GMP by phosphodiesterase type 5
How does PKG reduce smooth muscle tone?
→ Increase uptake of Ca2+
→ Myosin light chain dephosphorylation
→ Activates K+ channels causing hyperpolarization + closing VGCC
What do organic nitrates mimic?
→ Mimic the effects of endogenous nitric oxide
How do beta blockers reduce CO and lower blood pressure?
→ Inhibit funny current in the SA node
→ Reduce the force of cardiac contractions- improves exercise tolerance
act on beta 1 receptors in SA node and ventricular myocytes
How do beta blockers slow heart rate?
→ Lengthens diastole and gives more time for coronary perfusion
→ Improves myocardial oxygen supply
