Angina Flashcards
(39 cards)
What is the definition of angina and pectoris
Angina- from the Latin verb ‘angere’ meaning ‘to choke or throttle’
Pectoris- a reference to the Latin pectus (breast/chest)
What are symptoms of angina pectoris
Symptoms:
-feeling of cramping and severe constriction in the chest
-referred pain- jaw, shoulders, neck and arms
-may be associated with shortness of breath, sweating, nausea and heart rate
Explain how angina pectoris pain symptoms occur
1) Ischaemia- locally affected myocardium releases a variety of compounds including potassium, lactate, adenosine, bradykinin and prostaglandins
2) Activates myocardial pain receptors
3) Signal sent via sensory neurons to the brain
4) Pain perception
Explain the prevalence of angina pectoris
-chronic stable angina pectoris affects 2-4% of the population in western countries
Describe 3 traditional classifications of angina
Typical angina:
-substernal chest discomfort of characteristic quality and duration
-provoked by exertion or emotional stress
-relieved by rest and or nitrates within minutes
Atypical angina:
-presentation of two of the above characteristics
Non-anginal:
-presentation of only one or none of the chest pain characteristics
Explain 4 traditional angina (aetiology + chest pain symptoms)
Stable angina:
-attributed to myocardial ischemia
-coronary artery disease
Unstable angina:
-due to complications from stable angina
Prinzmetal angin:
-usually due to a spasm in the coronary arteries
-tends to happen in cycles
Microvascular angina:
-patients have angina symptoms but no evidence of coronary artery disease
-normal or near-normal coronary angiogram.
Explain what happens in stable angina:aetiology
-narrowed coronary artery lumen
-restricted blood flow to the area of myocardium it supplies
-the oxygen it receives is insufficient when the heart has to work harder
-anaerobic respiration
-pain
Explain characteristics of stable angina (classic, typical)
Characteristics of stable angina:
-follows a set pattern/predictable
-short duration radiation to left arm, neck, jaw and back
-precipitated by exertion/cardiac O2 demand
-not life threatening but can be warning sign for something serious (heart attack/stroke)
-relived by rest or taking medications
-symptoms attributed to myocardial ischemia
Explain what happens in unstable angina:aetiology
-clot formation occludes artery
-critical reduction in blood flow so that oxygen supply is inadequate at event at rest which causes pain
What are characteristics of unstable angina
characteristics of unstable angina:
-unpredictable
-pain symptoms more severe, can persist and last longer
-happens at rest with little exertion
-may not have a trigger
-not usually relieved by rest and medications
-progression from stable angina
-serious, regarded as emergency, patients are advised to go hospital
Explain prinzmetal angina: aetiology
-coronary spasm (caused by drugs like cocaine)
-critical reduction in blood flow so that oxygen supply is inadequate so that causes pain
Characteristics of prinzmetal angina (atypical/inversal/variant)
Characteristics of prinzmetal angina:
-usually occurs when resting and during the night
-episodes last 5-15 mins
-rare
-younger patients present with this
-attacks are very severe + painful
-pain may spread from chest-head-shoulder or arm
-symptoms: heart burn, nausea, sweating, dizziness, palpation, migraines
-cocaine use is leading cause in coronary vasospasms
Explain microvascular angina: aetiology
-impaired coronary circulation
-reduced coronary perfusion which leads to pain
What are characteristics of microvascular angina
Characteristics of microvascular angina:
-impaired coronary circulation due to coronary microvascular dysfunction from abnormal vasodilation or increased vasoconstriction
-patients do not have obstructive coronary artery disease
-occurs with exertion and at rest but may respond less but may respond less well to nitrates
-problem diagnosing it early as coronary microvascular cannot be directly imaged in vivo
-PET scans or cardiac magnetic resonance can be used to assess coronary microvascular blood flow
-treatment will vary depending on cause of the microvascular angina
What are treatment aims
the Treatment aims are:
-to enhance quality of life through reduction of symptoms
-to improve prognosis and prevent complications such MI and premature death
-well tolerated and cause minimal side effects
Explain what angina is
angina is an imbalance between demand and supply of oxygen to the heart
Explain how a thrombus can cause angina
A thrombus/blockage can cause unstable angina, which can cause vasospasm.
This can cause decreased coronary blood flow so there is supply ischaemia
This causes angina (chest pain)
Explain what happens in fixed stenosis to cause angina
Fixed stenosis (chronic stable angina)- increased oxygen requirement so there is a demand for ischaemia.
This causes angina (chest pain)
Explain precipitating factors for angina (chest pain)
Increased sympathetic activity:
-increased heart rate = less diastolic time, less coronary artery perfusion which only occurs in systole
Increased contractility:
-exercise, emotion, stress (greater oxygen demand)
Increased vasoconstriction:
-redistribution of blood flow in cold weather, after a large meal blood diverted to GI (vasoconstriction affects coronary circulation)
Explain angina treatment strategy
to Improve perfusion:
-increase oxygen delivery by improving coronary blood flow
-coronary vasodilators
To reduce metabolic demand:
-reduce oxygen demand by decreasing cardiac work
-vasodilators
-cardiac depressants
Prevention:
-prophylactic to reduce the risk of subsequent episodes
-lipid lowering drugs
-anti-coagulants
-fibrinolytic
-anti-platelet
explain the central role of calcium in smooth muscle contraction
Smooth muscle:
1) increase in cytoplasmic Ca2+ (most from interstitial fluid)
2) Ca2+ binding to calmodulin
3) Ca2+ leading to phosphorylation of myosin
4) Cross bridge cycle
5) Contraction by pulling actin along the myosin
Explain central role of calcium in heart muscle contraction
heart muscle:
1) increase in cytoplasmic Ca2+ all from sarcoplasmic reticulum
2) Ca2+ binding to troponin
3) Ca2+ causes troponin causing tropomyosin to move- exposing the myosin binding site on actin
4) Cross bridge cycle
5) Contraction by pulling actin along the myosin
What are examples of anti-anginal nitrates
examples:
-glyceryl trinitrate
-isosorbide mononitrate
What are effects of anti anginal nitrates
effects:
-peripheral venodilation—-> decrease intraventricular pressure —-> decreases cardiac preload
-arterial dilation—-> decrease total peripheral resistance——> reduces afterload
-both these actions lower oxygen demand by decreasing the work of the heart
