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20 Cards in this Set
- Front
- Back
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what is angina pectoris?
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ischemia (imbalance in O2 demand/supply)-> acidosis -> cardiac discomfort/pain
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what is typical angina?
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athlerosclerotic narrowing of coronary a.
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what is 'atypical' or 'variant' (Prinzmetal's) angina?
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coronary vasospasm
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what is 'unstable' angina?
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plt aggreg'n secondary to plaque rupture
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what determines cardiac O2 consumption?
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HR
ventricular wall stress (pressure, radius, wall thickness) ventricular contractility NOT metabolism |
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how does vascular tone affect ventricular wall pressure?
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↓ arteriolar tone = ↓ periph resistance = ↓ myocardial work / O2 consumption
↓ venous tone = ↑ capacitance = ↓ blood returned to heart (EDV = ventric wall tension = P x radius) |
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what are the therapeutic goals in angina?
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↑ perfusion, O2'n
↓ work, O2 demand --------------------- ↓ sx & freq of attack ↑ excercise tolerance |
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what are the therapeutic approaches in angina?
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vasodilators to ↓ sm m. tone
β-blockers to ↓ cardiac activity |
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what are 4 mechanisms for relaxing arterial smooth muscle?
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1) hyperpolariz'n = ↓ L channel openings (1° Ca+2 ch in sm m.)
2) block Ca+ L channels 3) ↑ cGMP (via NO) 4) ↑ cAMP (via β agonists) (causes pp'n of MLCK = inactivation = relax sm m. = vasodilation)- not really used therapeutically b/c it also stimulates ht. |
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what is the mechanism of NO?
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activates guanylate cyclase = ↑cGMP = de-pp'n of MLC = m. relax'n
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how do nitrates/nitrites work?
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produce/release NO
see 'mechanism of NO' |
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what CV effects do nitrates have at low doses?
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capacitance vessel effects =
venodilation (systemic periph resistance maintained) |
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what CV effects do nitrates have at high doses?
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resistance vessel effects =
↓ systemic periph resistance |
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are nitrates more resistant to metabolism more or less potent?
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less, b/c less NO released
can be used in larger doses safely longer half-life |
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what are some adverse effects of nitrates?
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flushing, headache, HYPO-TN, GI distress
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what are the short-acting forms of nitrates?
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nitroglycerin (sublingual)
isosorbide dinitrate (sublingual) act 10-60min |
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what are the long-acting forms of nitrates?
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nitroglycerin (oral)
isosorbide nitrate (oral) 4-8 hrs |
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what is the mechanism of sildenafil?
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inihibit PDE5 (a phosphodiesterase that breaks down cGMP)
↑ [cGMP] = enhanced erections in males whose *innervation and NO synthesis ability is intact* PDE5 predominantly in corpora cavernosa, so effects relatively selective |
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what are contraindicatiosn for sildenafil?
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use of nitrates for angina (sildenafil potentiates their action) --> severe hypoTN and ht attacks possible
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what are levitra (vardenafil HCl) and cialis (tadalafil)?
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struturally similar to sildenafil, also inhibit PDE5
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