Pharmacological Treatment of Angina Flashcards
What shrinks the window for coronary blood flow?
- shortening diastole (increasing HR)
- increased ventricular end diastolic pressure (aortic valve stenosis)
- reduced diastolic arterial pressure (eg. mitral/aortic valve incompetence or heart failure)
What are some causes of ischaemia?
- coronary ischaemia usually caused by atherosclerosis and cause angina
- sudden ischaemia usually caused by thrombosis and can cause MI
What are some causes of angina?
- coronary ischaemia
- coronary spasm (pathological vasomotion)
What is the result of prolonged ischaemia?
- cellular calcium overload
- can cause cell death and dysrhythmias
What causes the chest pain associated with angina pectoris?
inadequate oxygen supply to the heart
What is the character of the chest pain associated with angina?
- severe and crushing
- tight, constricting
- dull, heavy
Describe the distribution of pain associated with angina
- retrosternal/left side of chest
- can radiate to left arm/neck/jaw/back
- brought on by exertion/change in state (hot/cold)
What is thought as the cause of the angina pain?
- chemical factors that cause pain in skeletal muscle
- K+, H+, adenosine
What are the classes of angina and their type of ischaemia?
- stable angina: demand ischaemia
- unstable angina: supply ischaemia
- variant (Prinzmetal) angina: supply ischaemia
Stable angina
- fixed narrowing of coronary arteries
- predictable chest pain on exertion
- caused by a stressor
Unstable angina
- occurs at rest with less exertion than stable angina
- associated with thrombus around a ruptured atheromatous plaque
- incomplete occlusion of vessel
Variant (Prinzmetal) angina
- uncommon
- caused by coronary artery spasm
- sometimes associated with atherosclerosis
Drugs that reduce chest pain symptoms
- doesn’t treat underlying cause
- B-blockers
- nitrates
- Ca+ channel antagonists
- nirocandil
- ivabradine
- ranolazine
Drugs that prolong survival with angina
- B-blockers
- aspirin
- statins
- angiotensin converting enzyme inhibitors
- angiotensin II receptor blockers
What are the main lines of treatment of angina?
- short-acting nitrates for preventing/treating episodes of angina
- B-blocker given first
- if not CCB used
- can be given together
- if not/contraindications, nicorandil and ivabradine can be considered
Vasodilator antianginal drugs
- organic nitrates
- nicorandil
- calcium antagonists
- decrease preload/afterload
- decreases metabolic demand of muscle
HR lowering antianginal drugs
- B-blockers
- ivabradine
- prevents huge elevation in HR opening coronary window
- decreases metabolic demand of muscle
What drugs are organic nitrates?
- glyceryl trinitrate
- isosorbide mononitrate
How do organic nitrates work in treatment of angina?
- powerful vasodilators
- metabolise to NO to relax smooth muscle
- act on veins to decrease preload
- high concentrations increase afterload
- dilate collateral coronary vessels
- improves blood flow to regions of myocardium with restricted blood flow to restore perfusion more equally
- variant angina
Clinical applications of organic nitrates in angina
- stable angina: sublingual glyceryl trinitrate shortly before exertion/isosorbide mononitrate long before
- unstable angina/acute heart failure: IV glyeryl trinitrate
- chronic heart failure: isosorbide mononitrate with hydralazine in patients of african american origin esp
What are the side effects of organic nitrates?
- headache
- postural hypotension
Common B-blockers used in the treatment of angina
- bisoprolol
- atenolol
Explain the mechanism of action of B-blockers
- decreases cardiac oxygen consumption by slowing down HR
- increases period of diastole to allow perfusion of coronary arteries
Explain the mechanism of action of CCBs
- prevent opening of voltage-gated L-type Ca channels
- prevents Ca2+ entry
- stops constriction of smooth muscle
- vasodilator effect on resistance vessels and coronary vessels
- decreases afterload
