P14: Ischaemic Heart Disease Angina Flashcards
Does coronary perfusion happen in systole or diastole
only diastole
What local metabolic methods control coronary artery diameter
Local, transient ischaemia causes the release of vasoactive metabolites
What autonomic methods control coronary artery diameter
Larger coronary vessels = alpha1-adrenceptors, constriction
Smaller arteries = beta2-adrenceptors, relaxation
What is coronary stenosis
The narrowing of the arteries, leading to insufficient oxygen supply to the cardiac muscle
How is coronary stenosis often diagnosed
Sound of turbulent blood flow through the narrowed part of the artery
What is angina pectoris
A sensation of chest squeezing and pain, particularly following excercise, linked to stenosis
Is there a link between pain severity and myocardial oxygen deprivation
No, low pain can mean high deprivation and low deprivation
What is stable angina (effort angina)
Classic form of condition
Pain is minimal at rest and develops upon exercise or stress
Symptoms classically fade rapidly on rest
What is unstable angina (crescendo angina)
Angina that escalates
Commonly occur at rest or on minimal action
Severe and acute onset
Crescendo pattern - each episode is more severe than the last
What is the difference in the pathological process between stable and unstable angina
Chronic atherosclerosis - stable
Acute vascular blockade - unstable
What are the 3 stages of plaque development in athersclerosis
- Abnormal accumulation of lipid
- Fibrous tissue in the vessel wall narrows or occludes the vessel lumen
- Reduced blood flow
What is prinzmetal angina
coronary artery muscular spasm
Rupture of vessel plaque can lead to what
rapid thrombus development
What can untreated stable angina lead to
Unstable angina and then a heart attack
Name some risk factors for angina
Hypertension Hyperlipidaemia Smoking Diabetes Mellitus Obesity Being Male Stress Menopause Systemic infections
What is the goal of angina treatment
Reduce the workload of the heart and its oxygen consumption
What is the equation for heart workload
Stroke volume x arterial pressure x heart rate
What can affect heart workload besides the equation tings
Preload - venous return
Afterload - peripheral resistance
Sympathetic stimulation
What are the 3 main classes of pharmacological treatment for angina
- Organic Nitrate Donors
- Beta-Adrenoceptor antagonists
- Calcium channel blockers
Name some organic nitrate donor drugs for angina
Glyceryl trinitrate (short acting) Isosorbide Dinitrate (long acting)
Name some Beta-Adrenoceptor antagonists for angina
Propranolol
Atenolol
Name some calcium channel blocker drugs for angina
Nifedipine
Nicardipine
What are angina drugs supplemented with
Anti-platelets/Anti-thrombotics - aspirin
Antilipidaemic agents - statins
Describe the mechanism of organic nitrates
Widespread peripheral vasodilation
- Reduces preload by action on venules
- Reduces after load by peripheral arteriolar relaxation
Some action on coronary artery dilation
Give examples of organic nitrates
Glyceryl trinitrate
Isosorbide mono/dinitrate
What are the half lifes of glyceryl trinitrate and isosorbide mono/dinitrate
GT = 2 minutes IS/D = 1 hour
How are organic nitrates administered - give pros of each
Sublingual - fast acting, acute attack
Oral/Transdermal “nitropatch” slow release: maintenance therapy
IV - to control unstable angina
What are the adverse affects of organic nitrates
- Vasodilation and hypotension
- Met-haemoglobinaemia (increased O2 carrying capacity)
- Tolerance due to depletion of tissue thiols
Name some Beta-adrenoceptor antagonists and how they aim to work
Propanolol
Atenolol
Reduce O2 demand by decreasing cardiac workload
What receptors do Propanolol and Atenolol work at
Propanolol - Non-selective Beta1 and beta2 antagonists
Atenolol - Cardioselective Beta1 antagonist
What are the side effects of beta-adrenoceptor antagonists
Hypotension Bradycardia Bronchoconstriction Hyperlipidaemia Depression Fatigue reduced libido
What is the aim of calcium channel blocker drugs
Block entry of Ca2+ into muscle cells, reducing myocardial contractility, electrical impulse propagation and vascular tone
Name some cardiac favouring calcium channel blockers
Diltiazam
Verapamil
Describe the mechanism of cardiac favouring calcium channel blockers
Decreased SA node auromaticity and AV node conduction, resulting in decreased HR and decreased myocardial contractility
Name some vessel favouring calcium channel blockers
Nicardipine
Nifedipine
Describe the mechanism of vessel favouring calcium channel blockers
Relax blood vessels (arterial vasodilation) therefore decreased BP (workload) and increased coronary artery perfusion (increased oxygen supply)
What are the potential side effects of calcium channel blockers
Hypotension AV block Bradycardia Constipation Gastric Distress
What is the main surgical procedure after a myocardial infarction
Angioplasty
What is an angioplasty
When you use a stent and open it to open the block with a mesh ting
