Stable Angina

• STABLE ANGINA

  • Angina and acute coronary syndrome are both involved in chest pains caused by cardiac ischaemia
  • STABLE ANGINA = resolves with rest, few minutes
  • ACS = do not resolve quickly, or with rest
  • Types of angina include:

  1. stable and unstable angina
  2. prinzmetal's angina (variant angina)
  3. microvascular angina

  *all vessels constrict/ spasm ^^

  
• TREATMENT OF ANGINA

  • PROBLEM: too little O2 getting to cardiac muscle
  • SOLUTION:

  1. reduce O2 demand (reduce workload)
  2. increase O2 supply (improve blood flow)
• TREATMENT- ORGANIC NITRATES

  • drug options:

  1. statins (lipid lowering and prevents plaque worsening)
  2. aspirin (prevent platelet aggression)
  3. organic nitrates (glyceryl trinitrate/ amylnitrile/ isosorbide dinitrate/ nicorandi)
  4. beta blockers
  5. Ca2+ channel blockers
  6. K+ channel activators

  • GTN is ineffective is swallowed, must be given sublingually, ducally or patch

  1. avoids first pass metabolism
  2. duration of action 20-30 mins
• FIRST PASS METABOLISM

  
• VASODILATION INDUCED BY ORGANIC NITRATES

  • Nitrates relieve an attack of angina by:

  1. dilating coronary arteries, thereby improving coronary blood flow (coronary arteries already maximally dilated by metabolites fro ischaemic myocardium)
  2. reducing cardiac work and hence reducing the cardiac O2 demand (reduce by reducing preload- principal effect- and after load)

  • To reduce cardiac workload:

  1. dilute peripheral blood vessels (capacitance veins)
  2. heart does not have to push as hard
  3. less blood returned to heart: lower force of constriction
• CARDIOVASCULAR EFFETS OF ORGANIC NITRATES

  • Large doses of nitrates cause arteriolar dilation:

  1. fall in peripheral resistance
  2. reduction in cardiac after load
  3. reduces cardiac work

  • isosorbide mononitrate and dinitrate are long acting organic nitrates

  *effective when swallowed

  *dinitrate is metabolised initially to mononitrate

  *NOT released at site of action

  
• CARDIOVASCULAR EFFECTS OF ORGANIC NITRATES cont.

  • DINITRATE: tablets, sustained release tablets, sublingual tablets and bucal sprays
  • MONONITRATE: tablets and sustained release tablets
  • duration of action of sustained release tablets can be up to 12 hours
  • development of tolerance likely (can be minimised if doses spaced)
  • Unwanted effects of nitrates include:

  1. flushing of skin
  2. throbbing headache (dilation of cranical vessels)
  3. postural hypotension (fainting)
  4. reflex tachycardia
• TREATMENT- NICORANDIL

  • activator of K+ ATP channels and NO donor
  • dilates both arteries and veins
  • effects vs angina: similar to nitrates
  • unwanted effects: headache, flushing, hypotension, nausea and vomiting
• β-BLOCKERS

  • beta blockers reduce cardiac workload by:

  1. heart slows
  2. atria beats less forcibly
  3. ventricles beat less forcibly

  • cardiac work rate and O2 demand are reduced (principal effect)

  
• CORONARY ARTERY ANGIOPLASTY- SURGICAL TREATMENT

  • a catheter inserts a mesh metal tube (stent) into the blocked artery to keep it open
  • stents can either be bare stainless steel or impregenated with anti-inflammation drugs (drug eluting stents)
  • adverse effects include:

  1. stroke and myocardial infraction due to the angioplasty either triggering the formation of a blood clot, or dissuading one that's already formed (travels to smaller blood vessel and blocks it- embolism)
  2. angioplasty can lead to cognitive decline (blockage of small vessels in the brain)
  3. reternosis (re-closing) of artery
• CORONARY ARTERY BYPASS GRAFT- SURGICAL TREATMENT

  • removes a non-essential blood vessel from another part of the body and insert it to restore blood flow to the heart
  • most common vessel used: internal mammary artery and great saphenous vein (leg)
  • used to treat drug-resistant angina and location of blockage where stents cannot be used
  • grades last up to 15 years
  • adverse effects include:

  1. poor wound healing, blood loss and dysthymias
  2. myocardial infraction, stroke (due to embolisms and debris entering)
  3. cognitive decline