CAD - Wendt Flashcards
What factors contribute to increased oxygen consumption?
Increased HR, contractility, afterload, and preload
What is afterload?
The pressure in the veins that the heart has to match to push blood through the body
What is preload?
The volume of blood that enters the heart during diastole
If veins are dilated preload is (increased/decreased)?
Decreased
If preload is (increased/decreased), oxygen consumption increases?
Increased
What are risk factors for angina?
Age (>55 for men, >65 for women) Cigarette smoking Diabetes HTN Kidney disease Obesity Sedentary lifestyle
What two factors will increased coronary perfusion when they decrease?
HR and preload
How does preload increase the demand of the heart?
The heart has to stretch more to accommodate a larger blood volume
Why does a decreased HR increase coronary perfusion?
It allows the heart to spend more time in diastole, when blood can flow into coronary vessels
What are the 3 types of angina?
Printzmetal's Variant Chronic stable (fixed stenosis--narrowing of blood channel) Unstable (from thrombus)
What causes stable angina?
Atherosclerosis which causes oxygen demand to exceed supply
What factors precipitate stable agnina?
Exertion, food, emotions (stress, anger, etc)
What are the characteristics of variant angina?
Sudden and transient constriction; often occurs at rest and at night; hard to diagnosis because vessels look healthy
Is variant angina supply ischemia or demand ischemia?
Supply–cardiac myocytes don’t receive enough oxygen
What are characteristics of unstable angina?
A sudden worsening of angina at rest
What causes unstable angina?
Thrombosis or plaque rupture
What treatment strategy is used for unstable angina?
Inhibit platelet function, dissolve clot
Which type of angina often comes before an MI?
Unstable angina
What drug classes are used to increase oxygen delivery?
Vasodilators (CCBs, nitrates)
Anti-thrombotics (anticoags, antiplatelets)
What drug classes are used to decrease oxygen demand?
Vasodilators Cardiac depressants (beta blockers, CCBs, HCN channel inhibitor)
How does vasodilation occur via NO?
Endothelial cells produce eNOS –> increased NO production –> NO –> moves to VSM –> causes vasodilation by activating cGMP –> MLCP–> dephosphorylates MLC –> can’t bind to actin –> vasodilation
What are the organic nitrate drugs?
Glyceryl trinitrate
Isosorbide mononitrate
Isosorbide dinitrate
Which of the nitrates is longest acting?
Isosorbide mononitrate
Which of the nitrates is shortest acting?
GNT
Which of the nitrates are used for angina prophylaxis?
5-ISMN, ISDN
Which of the nitrates develop tolerance?
All organic nitrates
What is the mechanism of GTN tolerance?
mtALDH is sulfated irreversibly to activate GTN–run out of the enzyme as it is permanently inactivated
How long does GTN tolerance last?
a few hours
Are organic nitrates more effective in the veins or the arteries? Why?
Veins
Veins are more flexible/able to dilate
How do CCBs work?
Decrease Ca influx in myocytes
What do CCBs do?
Dilate arteries and decrease HR
CCBs primarily effect (preload/afterload)?
Afterload (dilating arteries decreases BP)
Why do CCBs not affect veins as much?
Veins have a larger calcium store in SR; rely less on extracellular calcium