Flashcards in Antianginals Deck (32)
At what point does the coronary circulation get most of its flow?
during diastole. There is an interruption of flow during systole because the muscle pumping press them closed.
What percent of CO does the coronary circulation get at rest and during stress?
What is related to the oxygen demand in coronary blood flow?
HR, contractility and preload/afterload
what is related to oxygen supply in coronary blood flow?
coronary patency, diastolic BP, blood O2 capacity and collateral circulation.
What is the flow of ischemic heart disease? O2 demand > O2 supply (atherosclerosis/angina)..
leads to hypoxia -> MI -> arrhythmias -> sudden death
What are the 3 kinds of angina pectoris?
typical (stable), variant (prinzmetals) and atypical (unstable).
What are the characteristics of typical angina?
fixed atherosclerotic narrowing, heavy substernal discomfort (sudden pain, physical, emotional stress) and nitro
What are the characteristics of variant angina?
coronary vasospasm, discomfort at rest and nitro
What are the characteristics of atypical (unstable) angina?
atherosclerotic plaque rupture, thrombosis, discomfort with stress or rest, unusual location, duration, inconsistent precipitating factors
What nitrates do we need to know?
nitroglycerin, isosorbide mono or dinitrate
What is the main action of nitrates?
smooth muscle dilator (veins > arterioles). Venodilation and decrease of preload!!!
What is the mechanism of venodilation by nitrates?
decreases venous return (preload) which leads to a decrease in end diastolic P/V which leads to decreases tension. Decreases O2 demand.
What are the three effects of nitrates?
venodilator, small decrease in PR and a coronary dilator
What effect does the small decrease in peripheral resistance of nitrates have? At a high dose?
small decrease in PR leads to a decreased afterload and decreased O2 demand.
At a high dose great decrease in PR leads to reflex tachycardia and increased O2 demand.
Nitro is a nitric oxide donor which leads to...
activates guanylyl cyclase which catalyzes cGMP which causes relaxation.
What are the uses of nitrates? How is it give?
Acute vs prophylaxis
acute stable, variant angina: sublingual NG
Prophylaxis: oral: Isosorb mono or dinitrate
What are the limitations of nitrates?
Tolerance: 8-12 hr free period
HA, hypotension and tachycardia
What beta blockers do we need to know for angina?
propranolol and metoprolol
What are the mechanisms of propranolol and metoprolol?
Reduce cardiac sympathetic effects: decreases HR, contractility and O2 demand
What is the prophylactic use of beta blockers?
Not used acutely. Decreases severity/frequency of stable angina. given post MI to reduce mortality.
Why are beta blockers not used in the tx of variant angina?
In variant angina there are vasospansms going on, and there are alpha and beta receptors on the arteries, so if you use a non-selective beta blocker the dilating receptor the dilating receptors will be blocked and vasoconstrictions will be left unopposed.
adverse effects of beta blockers?
cardiac suppression and rebound effect (heart increases # of beta receptors, need to be taken off of beta blockers SLOWLY)
precautions of beta blockers?
asthma, diabetes, HF, peripheral vascular disease
What Ca channel blockers do we need to know for antianginas?
Verapamil, Diltiazem and Nifedipine
What effect does Ca channel blockers have on smooth muscle?
decrease afterload (vasodilation), decrease O2 demand, decrease coronary resistance which leads to increased O2 supply.
N> V> D
What effect does Ca channel blockers have on cardiac muscle?
V> D>> N (little effect)
V,D: decreases HR, contractility and O2 demand (DIRECT EFFECT)
N: reflex tachycardia/sudden drop in BP (NO DIRECT EFFECT)
Used in stable and variant angina
Limitations o Ca channel blockers.
V/D: hypotension, bradycardia and decreased CO
N: hypotension, tachycardia
What effect with a nitrate and beta blocker combo have?
decrease in O2 demand and blunting of reflex tachycardia
What effect with nitrates with verapamil/diltiazem have?
decreased O2 demand and increased O2 supply
what effect will nitrates and nifedipine have?
hypotension and tachycardia. no bueno.
What effect will beta blockers and nifedipine have?
beta blocker blunts N's reflex tachycardia. bueno!