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Common Congenital Heart Lesions - page 51 / 126





51 / 126

51 of 126

START READING AGAIN: The main effect of the baroreceptor reflex is to reduce moment-by-moment changes in BP. The reflex is not involved in long term BP control and cannot prevent chronic HTN, because it resets to a baseline pressure in order to consistently prevent momentary changes.

Secondary Hypertension:

  • Relatively uncommon, but important to look at because of the potential to cure. Also if we wait too long to treat a cause of secondary HTN, the changes incurred may become permanent.

  • Clues for suspecting a secondary HTN:

    • o

      AGE: if hypertension develops before age 20 or after age 50

      • o

        SEVERITY: more severe hypertension (Stage 3)

      • o

        ONSET: abrupt onset in previously normotensive patient

      • o

        SIGNS of the cause: ex = bruit from renal artery stenosis

      • o

        FAMILY HISTORY: negative, usually occurs sporadically

  • Causes of Secondary HTN

        • 1.

          exogenous (medications)

        • 2.

          renal causes (renal parenchymal disease and renal artery stenosis)

        • 3.

          mechanical causes (coarctation of the aorta)

        • 4.

          endocrine causes (pheochromocytoma, adrenocortical hormone excess,

thyroid hormone excess)

~ The objectives suggest that we need to know signs, symptoms and lab findings for the 4 causes of secondary hypertension. Here we go. ~

  • 1)

    Exogenous Causes: Medications

    • oral contraceptives. Estrogens can increase hepatic synthesis of angiotensinogen, which leads to more ang II. More ang II causes vasoconstriction and increased aldosterone release, which will increase sodium retention = volume.

    • Glucocorticoids

    • Cyclosporine A

    • Erythropoietin (increased blood viscosity)

    • Sympathomimetic drugs (cold medicine)

    • Cocaine

    • Chronic alcohol consumption

  • 2)

    Renal Causes: two types

    • i.

      renal parenchymal disease

      • o

        Increased intravascular volume causes damage to the kidney.

        • o

          Damaged nephrons are unable to excrete normal amounts of water and Na, thereby increasing the volume further

        • o

          Can also involve secretion of lots of renin

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