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HYPERTENSION Hypertension is abnormal high blood pressure measured on at least three different occasions from a person who has been at rest at least 5 min.
HYPERTENSION In general, optimal pressures are considered less than 120 mm. Hg systolic and 80 mm. Hg diastolic, while pressures considered hypertensive are higher than 140 mm. Hg systolic, and higher than 90 mm. Hg diastolic
Causes of hypertension -Increased HR may occur with abnormal sympathetic or hormonal stimulation (T 4) to the SA node. -Chronically increased stroke volume may occur if there is a prolonged increase in plasma volume is reflected as an increase in end diastolic volume &hence increased SV &BP.
Causes of hypertension A prolonged increase in plasma volume may occur as a result of renal retention of salt and water, or it may result from excess salt consumption.
Causes of hypertension Increased end diastolic volume is referred to as an increase in the preload of the heart. Increased preload is usually associated with an increased systolic blood pressure.
Causes of hypertension Besides excess dietary intake of salt, abnormally increased renin or aldosterone levels or decreased blood flow to the kidneys also may alter renal handling of salt and water.
Causes of hypertension Chronically increased TPR may occur with increased sympathetic or hormonal stimulation to the arterioles, or with an overresponsiviness of the arterioles to normal stimulation, both of which would cause a narrowing of the vessels.
Causes of hypertension With increased TPR, the heart has to pump more forcefully, therefore exert more pressure, to drive the blood through the narrow vessels. This is referred to as an increase in the after load of the heart, and is usually associated with an increased DBP.
Causes of hypertension With prolonged increase in afterload, the left ventricle may begin to demands increase further, causing to pump even more forcefully to meet those demands.
Causes of hypertension For many people, increased sympathetic nerve stimulation, or perhaps overresponsivness of the body to normal sympathetic stimulation, may contribute to the development of hypertension.
Causes of hypertension This may result from a prolonged stress response, which is known to involve sympathetic activation, or from a genetic excess of receptors for nor epinephrine in the heart or vascular smooth muscle.
Causes of hypertension Other genetic influences may be racially determined. There is evidence that African Americans, who generally report more frequent and more severe hypertension, demonstrate an alteration in Na+-Ca++ pumping such that Ca++ accumulates in the smooth muscle cells, increasing muscle contraction and resistance.
TYPES OF HYPERTENSION Hypertension is often classified as either primary or secondary, based on whether a cause can be identified. Most cases of hypertension have no known cause and are called primary or essential hypertension. When a clear cause of hypertension can be identified , it is called secondary hypertension.
TYPES OF HYPERTENSION Secondary hypertension: An example of secondary hypertension is renal vascular hypertension, which develops as a result of renal stenosis. This condition may be congenital or a result of atherosclerosis.
HYPERTENSION Renal artery stenosis reduces blood flow to the kidney, leading to activation of renal baroreceptors, stimulation of renin release, and production of Ang. II. that increases ABP directly by increasing TPR &indirectly by increasing aldosterone synthesis and Na reabsorption.
HYPERTENSION Other causes of secondary hypertension include pheochomocytoma, an epinephrine secreting tumor of the adrenal gland, which causes increased HR &SV, &cushing’s disease, which causes increased SV from salt retension and increased TPR as a result of hypersensitivity of the sympathetic NS.
HYPERTENSION Primary aldosteronism &oral contraceptive may also cause secondary hypertension.
Hypertension in pregnancy ABP≥ 14090 mm. Hg occurs after 20 week’s gestation in a previously nonhypertensive woman, and reverses within 12 w. postpartum. (↑HR&↑TPR). If hypertension persists beyond 12 w. postpartum it is categorized as chronic hypertension.
Hypertension in pregnancy With preeclampsia, hypertension is accompanied by proteinurea (urinary excretion of at least 0. 3 g protein in 24 h), preeclampsia develops after 20 w.
Hypertension in pregnancy And is associated with decreased placental blood flow & the release of chemical mediators that cause dysfunction of vascular endothelial cells throughout the body.
HYPERTENSION Clinical manifestations: -Waking headache , nausia, vomiting caused by increased ICBP. -Blurred vision caused by hypertensive damage to the retina. -Dependent edema and swelling caused by increased capillary pressure.
HYPERTENSION Diagnostic tools -Measurement of ABP. -Proteinurea is present in women with preeclampsia.
HYPERTENSION Complications: -Stroke. -A myocardial infarct (MI) may occur if the atherosclerotic coronary arteries cannot supply adequate O 2 to the myocardium. -Renal failure. -Encephalopathy. -Seizures in women
HYPERTENSION -Weight loss. -Exercise -Relaxation (↓sympathetic stress response) -Stopping smoking. -Ca++channel blockers. -Ang. II converting enzyme inhibitors(ACE inhibitors)
HYPERTENSION -Beta blockers -Alpha blockers. -Arteriolar vasodilators. -Na restricted diet.