Drug Treatment of Angina and Acute Coronary Syndromes Flashcards
What is resting coronary blood flow usually? How does that change during exercise?
At rest 200ml/min (4% of output)
During exercise Coronary blood flow increases by 3 -4 timex initial amount but cardiac output increases by 6 - 9 times. The reason for this is that coronary circulation is blocked during systole and can only occur during diastole
How does oxygen demand increase from rest to exercise levels?
From 8 -> 70 ml O2/min per 100grams
What does oxygen demand of the heart depend on?
Heart work which is determined by heart rate cardiac contractility and afterload.
How can oxygen demand of myocardium be reduced?
Reducing heart rate and contractility through beta adrenoceptor blockers and calcium channel blockers.
Heart work can also be reduced by dilating peripheral vessels through the use of nitrates and calcium channel blockers (dihydropyridines)
What are nitrates?
Peripheral Vasodilators
How was glycerol trinitrate discovered as a vasodilator?
Workers with angina working in dynamite factories were reported to feel reduction in their symptoms on weekdays which returned on weekends.
What are some examples of Nitrates?
Glyceryl trinitrate
Isosorbide dinitrate
What compound do Glycerol trinitrate and isosobide dinitrate form?
NO (nitric oxide) which is a potent vasodilator
What enzyme forms NO from GTN and isosorbide dinitrate?
Organic Nitrate Ester Reductase
How is GTN taken in?
must be given via sublingual spray, IV, or transcutaneous patch.
How is isosorbide mononitrate?
Can be taken orally through a sustained release tablet
What is the limitation of using nitrates in the long term?
Tachyphylaxis: Effect loss over time (~24 hour). Should be taken intermittently as a result because the effect of NO is eventually lost
What do antiplatelet drugs do?
Used in all forms of coronary artery diseases
What are some examples of antiplatelet drugs?
Aspirin
Clopidogrel
Prasugrel; ticagrelor
What are acute coronary syndromes?
Unstable states where underlying pathology is a ruptured plaque and accumulation of platelets on it.
What are some examples of acute coronary syndromes?
Unstable angina
Non-ST elevation Acute MI
ST-elevation MI
What are some early drug management strategies for acute coronary syndromes?
Analgesia (morphine for pain relief)
Limitation of infarct size (coronary thrombolysis)
Antiplatelet and anticoagulant therapy (aspirin / heparin)
Management of acute heart failure (ACE inhibitors, nitrates, diuretics)
Anti-arrhythmic drugs (eg. beta adrenoceptor blockage)
(ALAMA)
What are some thrombolytic agents?
Streptokinase or altepase (decrease infarct size, complication, and mortality)
What are the forms of antiplatelet and anticoagulant therapy?
Aspirin and clapidogrel (inhibit platelet aggreggation on coronary plaque)
LMW heparin prevents thrombotic and embolic complications
What is the use of beta adrenergic blockers in early management of MI?
It limits infarct size
Helps pain
How can coronary heart disease be managed in the long term?
By limiting adverse outcomes of myocardial infarction:
Cardiac remodelling (drugs administered to decrease load on heart are made to prevent hypertrophy from occuring resulting in more MI)
Recurrent myocardial infarction
Arrhythmia and sudden death
What are the strategies to manage long term coronary heart disease?
Continued therapy:
Antiplatelet agents (reducing to single agent at 1 year)
Anticoagulants (where persisting thrombosis/embolism risk)
Beta 1 adrenergic blockage (to diminish risk of arrhthmia and cardiac remodelling)
Initiating new therapies must be done:
Risk factor management
Specific interventions
How are risk factors managed in people with acute coronary artery diseases?
Diabetes control
Blood Pressure control
Lipids (statins, and reduced target concentrations with anyone that has a history of coronary heart disease)
Stop smoking
What does a stemi look like on an ECG?
elevated T segment
What is the initial management of a STEMI?
MOAN
Morphine (opioids)
Oxygen
Aspirin +clopidogrel
Nitrates
What are the treatments of a STEMI after the initial management?
Primary cutaneous coronary intervention (using a deflated balloon)
Fibrinolytic therapy (streptokinase, alteplase)
