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Spasm of vascular smooth muscleSpasm of vascular smooth muscle Or due to Or due to Obstruction of blood vessels caused by Obstruction of blood vessels caused by
atherosclerotic lesionsatherosclerotic lesions
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Stable vs Unstable
Angina pains normally occur during periods of physical exertion.
‘unstable angina’ is used to describe pains which occur at rest
•Severe coronary disease
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Exertion is the most common cause of pain and Exertion is the most common cause of pain and
discomfort from discomfort from stable anginastable angina. Severely narrowed . Severely narrowed arteries may allow enough blood to reach the heart arteries may allow enough blood to reach the heart when the demand for oxygen is low (such as when when the demand for oxygen is low (such as when you are sitting). But with exertion, like walking up a you are sitting). But with exertion, like walking up a hill or climbing stairs, the heart works harder and hill or climbing stairs, the heart works harder and needs more oxygen. Other causes include: needs more oxygen. Other causes include:
Emotional stress Emotional stress Exposure to very hot or cold temperature Exposure to very hot or cold temperature Heavy meals Heavy meals Smoking Smoking
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Unstable AnginaUnstable Angina Unstable angina is caused by blood clots that Unstable angina is caused by blood clots that
partially or totally block an artery. If plaque in an partially or totally block an artery. If plaque in an artery ruptures or breaks open, blood clots may artery ruptures or breaks open, blood clots may form. This creates a larger blockage. The clot form. This creates a larger blockage. The clot may grow large enough to completely block the may grow large enough to completely block the artery and cause a heart attack. Blood clots may artery and cause a heart attack. Blood clots may form, partly dissolve, and later form again. Chest form, partly dissolve, and later form again. Chest pain can occur each time a clot blocks an artery. pain can occur each time a clot blocks an artery.
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Variant AnginaVariant Angina Variant angina is caused by a spasm in a coronary Variant angina is caused by a spasm in a coronary
artery. The spasm causes the walls of the artery to artery. The spasm causes the walls of the artery to tighten. This narrows the artery, causing the blood tighten. This narrows the artery, causing the blood flow to the heart to slow or stop. Variant angina may flow to the heart to slow or stop. Variant angina may occur in people with and without CAD. Other causes occur in people with and without CAD. Other causes of spasms in the arteries that supply the heart with of spasms in the arteries that supply the heart with blood are: blood are:
Exposure to cold Exposure to cold Emotional stress Emotional stress Medications (vasoconstricting) that constrict or narrow Medications (vasoconstricting) that constrict or narrow
blood vessels blood vessels Cigarette smoking Cigarette smoking Cocaine use Cocaine use
RELEASES NO , which in turn activates RELEASES NO , which in turn activates guanylate cyclase and increase cyclic GMP guanylate cyclase and increase cyclic GMP levelslevels
Cyclic GMP causes dephosphorylation of Cyclic GMP causes dephosphorylation of myosin light chains resulting in vascular myosin light chains resulting in vascular smooth muscle relaxationsmooth muscle relaxation
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VASO DILATION, MORE VASO DILATION, MORE VENODILATIONVENODILATION
DECREASES PRELOADDECREASES PRELOAD
DECREASES OXY . DEMANDDECREASES OXY . DEMAND
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KINETICS
ONSET OF ACTIONONSET OF ACTION NITROGLYCERIN < 1 MINNITROGLYCERIN < 1 MIN
FIRST PASS METABOLISM : SIGNIFICANTFIRST PASS METABOLISM : SIGNIFICANT
ROUTES OF ADMIN. SUBLINGUALROUTES OF ADMIN. SUBLINGUAL
Continuous administration of nitrates may Continuous administration of nitrates may lead to tolerance of their clinical efficacy. lead to tolerance of their clinical efficacy.
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SIDE EFFECTS MC: Headache MC: Headache The most common side effect of nitrates The most common side effect of nitrates
is headache. For most people, headaches subside after a few is headache. For most people, headaches subside after a few
daysdays Dizziness, weakness due to postural Dizziness, weakness due to postural
hypotension. hypotension.
Drug rash, especially with Pentaerythritol Drug rash, especially with Pentaerythritol tetra nitrate. tetra nitrate.
Aspirin, an antiplatelet drug, reduces the Aspirin, an antiplatelet drug, reduces the risk of heart attacks and death. Antiplatelet risk of heart attacks and death. Antiplatelet drugs make blood clots less likely to form drugs make blood clots less likely to form by preventing platelets from sticking by preventing platelets from sticking together. together.