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diuretics, such as spironolactone, which is an aldoste- rone antagonist, often are used in the medical manage- ment of persons with bilateral hyperplasia. Pheochromocytoma. Pheochromocytomas are rare catecholamine-secreting tumors of adrenal chromaffin cells. 30 They can occur at any age, including infancy, but are uncommon after 60 years of age. They can occur as part of hereditary syndromes, but most are sporadic. Of the sporadic tumors, about 10% are malignant. 46 Like adrenal medullary cells, the tumor cells of a pheo- chromocytoma produce and secrete the catecholamines epinephrine and norepinephrine. The hypertension that develops is a result of the massive release of these cat- echolamines. Their release may be paroxysmal rather than continuous, causing periodic episodes of head- ache, excessive sweating, and palpitations. Headache is the most common symptom and can be quite severe. Nervousness, tremor, facial pallor, weakness, fatigue, and weight loss occur less frequently. Marked variability in blood pressure between episodes is typical. Diagnostic methods include urinary and blood assays for catecholamines and their metabolites and CT and MRI studies to locate tumors and possible metastases. Surgical removal of the tumor or tumors is the treat- ment of choice. If the tumor is not resectable, treatment with drugs that block the action or synthesis of cate- cholamines can be used. When correctly diagnosed and treated, most pheochromocytomas are curable. When they are undiagnosed or improperly treated, they can be fatal. 30–46 Coarctation of the Aorta. Coarctation of the aorta or aortic coarctation is a congenital condition in which a narrowing or constriction of the lumen of the aorta exists. 47 In the adult form, narrowing most commonly occurs just distal to the origin of the subclavian (see Chapter 19). The ejection of a large stroke volume into a narrowed aorta results in an increase in systolic blood pressure and blood flow to the upper part of the body. Blood pressure in the lower extremities may be normal, although it frequently is low. It has been suggested that the increase in cardiac output and maintenance of the blood pressure to the lower part of the body is achieved through the renin-angiotensin-aldosterone mechanism in response to a decrease in renal blood flow. Coarctation of the aorta should be considered as a cause of secondary hypertension in young people with an elevation in blood pressure. Because the aortic capac- ity is diminished in coarctation of the aorta, there usu- ally is a marked increase in pressure (measured in the arms) during exercise, when the stroke volume and heart rate are exaggerated. Pulse pressure in the legs almost always is narrowed, and the femoral pulses are weak. It is important that blood pressure be measured in both arms and one leg when coarctation of the aorta is suspected. A pressure in the arms 20 mm Hg or more higher than in the legs suggests coarctation of the aorta. Treatment consists of surgical repair or balloon angioplasty. Although balloon angioplasty is a relatively recent form of treatment, it has been used in children

and adults with good results. However, there are few data on long-term follow-up. Oral Contraceptive Drugs. The use of oral contracep- tive pills is probably the most common cause of second- ary hypertension in young women. Women taking oral contraceptives should have their blood pressure taken regularly. 30 The cause of the increased blood pressure is largely unknown, although it has been suggested that the probable cause is volume expansion because both estro- gens and synthetic progesterones used in oral contracep- tive pills cause sodium retention. Various contraceptive drugs contain different amounts and combinations of estrogen and progestational agents, and these differences may contribute to the occurrence of hypertension in some women but not others. Fortunately, the hyperten- sion associated with oral contraceptives usually disap- pears after the drug has been discontinued, although it may take as long as 3 months for this to occur. However, in some women the blood pressure may not return to normal, and they may be at risk for development of hypertension. The risk for hypertension-associated car- diovascular complications is found primarily in women older than 35 years of age and in those who smoke. Target-Organ Damage Hypertension is typically an asymptomatic disorder. When symptoms do occur, they are usually related to the long-term effects of hypertension on other organ systems, termed target organs , such as the kidneys, heart, eyes, and blood vessels 29 (Chart 18-2). The excess morbidity and mortality related to hypertension is pro- gressive over the whole range of systolic and diastolic pressures, with target-organ damage varying markedly among persons with similar levels of hypertension. Hypertension is a major risk factor for atheroscle- rosis; it predisposes to all major atherosclerotic cardio- vascular disorders, including coronary heart disease, heart failure, stroke, and peripheral artery disease. The risk for coronary artery disease and stroke depends to a great extent on other risk factors, such as obesity, smoking, and elevated cholesterol levels. In clinical

CHART 18-2   Target-Organ Damage Heart

■■ Left ventricular hypertrophy

■■ Angina or prior myocardial infarction ■■ Prior coronary revascularization

■■ Heart failure Brain

■■ Stroke or transient ischemic attack Chronic kidney disease Peripheral vascular disease Retinopathy

From the National Heart, Lung, and Blood Institute. The Seventh Report of the National Committee on Detection, Evaluation, andTreatment of High Blood Pressure. Publication No. 03–5233. Bethesda, MD: National Institutes of Health; 2003.