Hypertension PDF

Hypertension Hypertension is the leading risk factor for cardiovascular disorders. It affects approximately 50 million individuals in the United States and approximately 1 billion persons world- wide. Men have higher blood pressures than women up until the time of menopause, at whic...

Hypertension Hypertension is the leading risk factor for cardiovascular disorders. It affects approximately 50 million individuals in the United States and approximately 1 billion persons world- wide. Men have higher blood pressures than women up until the time of menopause, at which point women quickly lose their protection. The prevalence of hypertension increases with age.  Hypertension commonly is divided into the categories of primary and secondary hypertension. In primary, or essential, hypertension, the chronic elevation of blood pressure occurs without evidence of other disease conditions. Primary hypertension accounts for approximately 90% to 95% of all cases of hypertension. In secondary hypertension, the elevation of blood pressure results from some other disorder, such as kidney disease.  Hypertension is diagnosed when the systolic pressure is consistently elevated above 140 mm Hg, or the diastolic blood pressure is 90 mm Hg or higher. Hypertension is further divided into stages 1 and 2 based on systolic and diastolic blood pressure measurements Screens.  Primary (Essential) Hypertension: Essential (primary) hypertension is the term applied to hypertension for which no cause can be identified. Constitutional risk factors include family history of hypertension, race, and age-related increases in blood pressure. Hypertension not only is more prevalent in blacks than whites, but also is more severe. Maturation and growth are known to cause predictable increases in blood pressure.  Lifestyle factors include high salt intake, excessive calorie intake and obesity, and excessive alcohol consumption. Excessive weight commonly is associated with hyper- tension. It has been suggested that fat distribution might be a more critical indicator of hypertension risk than actual overweight. Recent evidence indicates that leptin, may represent a link between adiposity and increased cardiovascular sympathetic activity.  Secondary Hypertension: Secondary hypertension, accounts for 5% to 10% of hypertension cases. Unlike essential hypertension, many of the conditions causing secondary hypertension can be corrected or cured by surgery or specific medical treatment. Among the most common causes of secondary hypertension are kidney disease, adrenal cortical disorders, pheochromocytoma, and coarctation of the aorta.  Renal Hypertension Most acute kidney disorders result in decreased urine formation, retention of salt and water, and hypertension. This includes acute glomerulonephritis, acute renal failure, and acute urinary tract obstruction. Renovascular hypertension refers to hypertension caused by reduced renal blood flow and activation of the RAAS. It is the most common cause of secondary hypertension.  There are two major types of renovascular disease: 1. Atherosclerosis of the proximal renal artery. 2. Fibromuscular dysplasia, a noninfammatory vascular disease that affects the renal arteries and branch vessels. Atherosclerotic stenosis of the renal artery accounts for 70% to 90% of cases and is seen most often in older persons. Fibromuscular dysplasia is more common in women and tends to occur in younger age groups.  Diagnostic tests for renovascular hypertension may include studies to assess overall renal function, and imaging studies to identify renal artery stenosis. Renal arteriography remains the definitive test for identifying renal artery disease. Duplex ultrasonographic scanning, contrast-enhanced CT scans, and magnetic resonance angiography (MRA) are other tests that can be used to screen for renovascular hypertension. Atherosclerotic stenosis Fibromuscular dysplasia  The goal of treatment for renal hypertension is to control the blood pressure and stabilize renal function. Angioplasty or revascularization has been shown to be an effective long-term treatment for the disorder. Angiotensin-converting enzyme (ACE) inhibitors may be used in medical management of renal stenosis. However, these agents must be used with caution because of their ability to produce marked hypotension and renal dysfunction.  Disorders of Adrenocortical Hormones: Increased levels of adrenocortical hormones also can give rise to hypertension. Primary hyperaldosteronism and excess levels of glucocorticoid (Cushing syndrome) tend to raise the blood pressure. For patients with primary hyperaldosteronism, a sodium-restricted diet often produces a reduction in blood pressure.  Screening tests for primary hyperaldosteronism involve the determination of plasma aldosterone concentration and plasma rennin activity. Computed tomography and magnetic resonance imaging scans are used to localize the lesion. Persons with solitary adenomas are usually treated surgically. Potassium-sparing diuretics which is an aldosterone antagonist, often are used in the medical management of persons with bilateral hyperplasia.  Pheochromocytoma Pheochromocytoma are rare catecholamine-secreting tumors of adrenal chromaffin cells. The hypertension that develops is a result of the massive release of these catecholamines. Their release may be paroxysmal rather than continuous, causing periodic episodes of headache, excessive sweating, and palpitations. Nervousness, tremor, facial pallor, weakness, fatigue, and weight loss occur less frequently. Marked variability in blood pressure between episodes is typical.  Oral Contraceptive Drugs The use of oral contraceptive pills is probably the most common cause of secondary hypertension in young women. Women taking oral contraceptives should have their blood pressure taken regularly. The probable cause is volume expansion because both estrogens and synthetic progesterones used in oral contraceptive pills cause sodium retention. Hypertension associated with oral contraceptives usually disappears after the drug has been discontinued.  Lifestyle Modification Lifestyle modification has been shown to reduce blood pressure, enhance the effects of antihypertensive drug therapy, and prevent cardiovascular risk. Major lifestyle modifications shown to lower blood pressure include weight reduction in persons who are overweight or obese. Regular physical activity, reduction of dietary sodium intake, and limitation of alcohol intake.  Hypertensive Crisis Hypertensive crisis is defined as a systolic pressure greater than 180 or a diastolic pressure greater than 120 mm Hg. Hypertensive crisis can be further classified as hypertensive urgency or a hypertensive emergency depending on end-organ involvement including cardiac, renal, or neurologic injury. Hypertensive urgency is defined by a markedly elevated blood pressure, but without the rapid progression of target-organ involvement.  Hypertensive emergency occurs when elevated blood pressure is responsible for symptoms, signs, or laboratory evidence of end-organ damage, such as mental status changes. Cerebral vasoconstriction probably is an exaggerated homeostatic response designed to protect the brain from excesses of blood pressure and flow. The goal of initial treatment is to obtain a partial reduction in blood pressure to a safer, less critical level, rather than to normotensive levels.  High Blood Pressure in Pregnancy Hypertensive disorders complicate 5% to 10% of pregnancies and remain a major cause of maternal and neonatal morbidity and morality. Preeclampsia–eclampsia is a pregnancy-specifc syndrome with both maternal and fetal manifestations. It is defined as an elevation in blood pressure (systolic blood pressure >140 mm Hg or diastolic pressure >90 mm Hg) and proteinuria (≥300 mg in 24 hours) developing after 20 weeks of gestation.  Preeclampsia occurs primarily during first pregnancies and during subsequent pregnancies in women with multiple fetuses, diabetes mellitus, or underlying kidney disease. Eclampsia is the occurrence, in a woman with preeclampsia, of seizures that cannot be attributed to other causes. Considerable evidence suggests that the placenta is a key factor in all the manifestations because delivery is the only definitive cure for this disease.  Gestational Hypertension Gestational hypertension is defined as the development of new hypertension without proteinuria occurring after 20 weeks’ gestation, which resolves within 12 weeks of termination of the pregnancy. The final diagnosis of gestational hypertension is made only postpartum. Women with gestational hypertension progress to preeclampsia in 15% to 45% of cases and often require early delivery. Surveillance for development of preeclampsia and close fetal monitoring are recommended.  Diagnosis and Treatment Early prenatal care is important in the detection of high blood pressure during pregnancy. Bed rest is a traditional therapy. Antihypertensive medications, when required, must be carefully chosen because of their potential effects on uteroplacental blood flow and on the fetus. For example, the ACE inhibitors can cause injury and even death of the fetus when given during the second and third trimesters of pregnancy.