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6 Cards in this Set
- Front
- Back
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What is the role of the Renin-Angiotensin-Aldosterone System?
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Renin produces Angiotensin I. Angiotensin I is inactive until it is converted to Angiotensin II by the ACE. Angiotensin II stimulates the production of aldosterone (by the adrenal medulla) which increases retention of H2O and Na which in turn increases circulating volume. The vasoconstricting effect of Angiotensin II and the increase of circulating volume caused by the aldosterone increase cardiac output and peripheral resistance, thus, increasing BP. These hormones also increase growth of cells and mass of arterial walls and the left ventricle. Problems such as inflammation of vessels, thrombosis, oxidative stress, CHF, arrythmia, reduced fibrinolysis, & sudden cardiac death are more likely to occur because of these two hormones. Aldosterone can cause structural renal injury, proteinuria, collagen synthesis, myocardial fibrosis, and cardiac damage.
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How do diuretics affect BP?
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Diuretics promotes excretion of H2O and Na which decreases circulating volume. This decrease also causes the decrease in peripheral resistance and in turn decreasing BP. Low-dose thiazides can be combined with beta blockers, calcium channel blockers, ACE inhibitors, and ARBs to control BP. Diuretics increase the efficacy of other antihypertensives.
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Benazepril (Lotensin)
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ACE inhibitor
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Doxazosin (Cardura)
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An Alpha-1 blocker which promotes vasodilation of resistance (arterioles) and capacitance (veins) vessels. This decreases BP particularly diastolic with a first-dose effect of orthostatic hypotension. The Alpha-1 blockade causes increase in urine flow rate because of the relaxation of the smooth muscle in the bladder neck and prostate gland. It is used to treat benign prostatic hypertrophy/hyperplasia and CHF w/ digoxin.
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Hydralazine
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A direct-acting vasodilator which relaxes arterioles, decreases peripheral resistance thereby decreasing BP. It is not suitable for monotherapy; must be given with 2 beta-blockers and a diuretic to control BP, prevent reflex tachycardia, & SLE & decrease fluid retention. Pt. education includes learning to report signs of SLE. Other adverse effects are angina and anorexia.
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Drugs for Hypertensive Crisis
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Nitroprusside (Nitropress), Diaxozide (Hyperstat IV), Phentolamine (Regitine)
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