Cause: 15-18% of adults in the U.S. are hypertensive. Essential HT represents 90-94% of all cases seen. Other causes include chronic renal disease (chronic nephritis, polycystic kidney disease, diabetic nephropathy, hydronephrosis), renovascular disease, coarctation of aorta, Cushing’s syndrome, primary aldosteronism, pheochromocytoma, acromegaly, hyperthyroidism, hyperparathyroidism, cardinoid syndrome, increased intracranial pressure of any cause, acute porphyria, lead poisoning, Guillain-Barré syndrome, use of oral contraceptives, NSAIDs, ETOH, cocaine, PCP, steroids, cyclosporine, tacrolimus, erythropoietin, and licorice (also found in some chewing tobacco and ephedra; Lancet 2003;361:1629).
A study of 297 hypertensivepts undergoing angiography found 19.2% incidence of renal artery stenosis > 50%; 7% had stenosis > 70%, and 3.7% had bilateral renal artery stenosis (Mayo Clin Proc 2002;77:309).
Epidem:HT is reported to be 2-3 times more common in women taking oral contraceptives, especially in obese and older women, than in those not taking oral contraceptives. Postmenopausal estrogen replacement is not associated with a significant increase in BP.
Among Americans ≥ age 60, elevated BP is found in 60% of non-Hispanic whites, 71% of non-Hispanic African Americans, and 61% of Mexican Americans.
HT is associated with obesity, sleep apnea, physical inactivity, cigarette smoking, ETOH (> 3 oz spirits/d), polycythemia, and hyperuricemia.
Sleep-disordered breathing may be a risk factor for HT in the general population (Nejm 2000;342:1378).
Pathophys: The mechanisms of essential HT are unknown.
Sx: Uncomplicated HT is usually asymptomatic. Sx frequently attributed to HT (headache, facial flushing, tinnitus, lightheadedness) are equally prevalent in the normotensive population.
Si: Possible physical exam findings: hypertensive retinopathy (arteriolar narrowing, focal arteriolar constrictions, arteriovenous crossing changes, hemorrhages and exudates, disc edema); carotid bruits, distended veins, irregular or rapid heartbeat, cardiomegaly, precordial heave, clicks, murmurs, S3, S4; rales; abdominal bruits, abnormal aortic pulsation; diminished/absent peripheral arterial pulsations, bruits, edema. Headache, palpitations, pallor, and perspiration suggest pheochromocytoma. Delayed/absent femoral arterial pulses and decreased BP in lower extremities suggest aortic coarctation. Truncal obesity with purple striae is seen in Cushing’s syndrome.
Crs: Individuals normotensive at age 55 have a 90% lifetime risk for development of HT. BP of 130-139/85-89 is associated with increased risk of CVD (Nejm 2001;345:1291) and may progress to stage 1 HT over the next 4 yr (Lancet 2001;358:1682). In the Framingham Heart Study, all-cause mortality was lower among men with long-term rx of HT (31% vs 43%), and CVD mortality was less than half (13% vs 28%). Among treated women, all-cause mortality was 21% vs 34%, and CVD mortality was 9% vs 19% (Circ 1996;93:697). Rx of HT is associated with reduction in stroke incidence of 35-40%, MI 20-25%, and CHF > 50%.
Pts with adequate BP control on captopril, HCTZ, and atenolol showed reduction of LV mass after 1 yr;pts on diltiazem, clonidine, or prazosin did not (Circ 1997;95:2007). In a meta-analysis, ACEIs were more potent than β-blockers and diuretics in the reduction of LV mass index (Jama 1996;275:1507).
Cmplc: The risk of CVD doubles with each increment of 20/10 mmHg beginning with a BP of 115/75. 50% ofpts with untreated HT die of ASHD/CHF, 33% die of CVA, and 10-15% die of renal failure. HT is the major cause of LV failure in the U.S. (Framingham Heart Study).
Lab: For allpts: EKG, serum glucose, electrolytes, Ca++, creatinine, CBC, UA; consider thyroid function studies, especially in elderly; lipid profile for risk stratification
If pt age, hx, severity of HT, or initial labs suggest secondary HT, or if BP is unresponsive to rx or begins to increase, or if the onset of HT is sudden, test for pheochromocytoma (24-hr urine for total catecholamines or metanephrine/vanillylmandelic acid) or mineralocorticoid abnormalities (plasma renin activity, plasma aldosterone, urine aldosterone and Na+); for latter, pt must be on a high-salt diet in the absence of β- and Ca++-channel blockers, ACEIs, or thiazide diuretics; control BP with clonidine or α-blockers
The metanephrine/creatinine ratio is a sensitive and specific test for pheochromocytoma, but acute events may increase urinary metanephrine excretion (Ann IM 1996;125:300).
X-ray:CXR if cardiac disease suspected; captropril renal scan, renal duplex US if likelihood of renovascular HT is moderate (abdominal bruit, age < 20 yr, HT refractory to standard rx, pt with occlusive vascular disease); renal arteriography forpts with high likelihood (malignant HT, Grade 4 HT with progressive renal insufficiency)
Rx:JNCX-7 classifies BP as normal or ideal, prehypertensive or nonideal, stage 1, stage 2 (Table 11.1)
Table 11.1 Classification and Management of Blood Pressure for Adults1
2 . Initial combined therapy should be used cautiously in those at risk for orthostatic hypotension.
3 . Treat patients with chronic kidney disease or diabetes to BP goal of < 130/80 mmHg. (JNCX-7)
Initial BP follow-up recommendations (JNC-6): < 130 mmHg systolic or < 85 mmHg diastolic, recheck in 2 yr; if 130-139 or 85-89, recheck 1 yr; 140-159 or 90-99, confirm within 2 mon; 160-179 or 100-109, evaluate or refer to source of care within 1 mon; > 180 or > 110, evaluate or refer to source of care immediately or within 1 wk, depending on clinical situation
Diet: Avoid high intake of NaCl; increase intake of fruits, vegetables, and fat-free and low-fat dairy products (Nejm 1997;336:1117; 2001;344:3). For the general population, AHA recommends average daily consumption of NaCl by adults < 6 gm (Circ 1998;98:613). However, in 58 trials of hypertensive persons, the effect of reduced Na+ intake on SBP was 3.9 mmHg and on DBP was 1.9 mmHg (Jama 1998;279:1383). In prevention trials, change in BP was more convincingly related to change in weight than to change in dietary salt.
Other lifestyle measures: Lose weight if overweight; limit alcohol intake to 1 ozqd, 0.5 ozETOHqd for women and lighter-weight people; increase aerobic physical activity; reduce Na+ intake to 2.4 g Na+/6 gmNaClqd; maintain adequate intake K+, Ca++, Mg+; stop smoking.
Table 11.2 Lifestyle Modifications to Manage Hypertension
Limit consumption to no more than 2 drinks (1 oz or 30 mL ethanol; eg, 24 oz beer, 10 oz wine, or 3 oz 80-proof whiskey) per day in most men and to no more than 1 drink per day in women and lighter-weight persons.
Review of trials (16,164pts ≥ 60 yr): Diuretic rx is effective in preventing CVA/TIA, CAD, cardiovascular, and all-cause mortality. β-blockers in these studies reduced the odds for CVA/TIA but did not prevent CAD or reduce cardiovascular and all-cause mortality (Jama 1998;279:1903).
Thiazide diuretics are effective initial rx in mostpts. The primary focus is attaining the systolic BP goal. The diastolic BP goal is usually reached once systolic BP is controlled. In olderpts with systolic HT, chlorthalidone is protective against CHF; inpts with prior MI, the risk is reduced 80% (Jama 1997;278:212). Rx of systolic HT inpts > age 60 is most effective in those at high risk for CAD (Circ 2001;104:1923).
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