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Essential hypertension

Hypertension or high blood pressure is a medical condition where the blood pressure is chronically elevated. While it is formally called arterial hypertension, the word "hypertension" without a qualifier usually refers to arterial hypertension. more...

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Persistent hypertension is one of the risk factors for strokes, heart attacks, heart failure and arterial aneurysm, and is a leading cause of chronic renal failure.


Blood pressure is a continuous variable, and risks of various adverse outcomes rise with it. A blood pressure of less than 120/80 mmHg is defined as "normal" in adults. Hypertension is usually diagnosed on finding blood pressure of 140/90 mmHg or above, measured on both arms on three occasions over a few weeks.

Recently, the JNC VII (The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure) has defined blood pressure 120/80 mmHg to 140/90 mmHg as "prehypertension". Prehypertension is not a disease category. Rather, it is a designation chosen to identify individuals at high risk of developing hypertension (JNC VII).

In patients with diabetes mellitus or kidney disease studies have shown that blood pressure over 130/80 mmHg should be considered a risk factor and may warrant treatment.


Essential hypertension

  • Age. Over time, the number of collagen fibres in artery and arteriole walls increases, making blood vessels stiffer. With the reduced elasticity comes a smaller cross-sectional area in systole, and so a raised mean arterial blood pressure.
  • High salt intake
  • Sedentary lifestyle
  • Tobacco smoking
  • Alcohol abuse
  • High levels of saturated fat in the diet
  • Obesity. In obese subjects, losing a kilogram of mass generally reduces blood pressure by 2 mmHg.
  • Stress
  • Low birth-weight
  • Diabetes mellitus
  • Various genetic causes

Secondary hypertension

While most forms of hypertension have no known underlying cause (and are thus known as "essential hypertension" or "primary hypertension"), in about 5% of the cases, there is a known cause, and thus the hypertension is secondary hypertension.


The mechanisms behind the factors associated with inessential hypertension are generally fully understood, and are outlined at secondary hypertension. However, those associated with essential hypertension are far less understood. What is known is that cardiac output is raised early in the disease course, with total peripheral resistance normal; over time cardiac output drops to normal levels but TPR is increased. Three theories have been proposed to explain this:

  • Inability of the kidneys to excrete sodium, resulting in natriuretic factor (note: the existence of this substance is theoretical) being secreted to promote salt excretion with the side-effect of raising total peripheral resistance.
  • An overactive renin / angiotension system leads to vasoconstriction and retention of sodium and water. The increase in blood volume leads to hypertension.
  • An overactive sympathetic nervous system, leading to increased stress responses.


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Obstructive Sleep Apnea and Essential Hypertension—Is There a Link?
From American Family Physician, 1/15/02 by Benjamin W. Chaska

Obstructive sleep apnea (OSA) occurs in 2 percent of women and 4 percent of men between 30 and 60 years of age.(1) (This compares with an incidence of 4.5 percent for asthma in this age category.)(2) OSA is infrequently diagnosed. The National Center on Sleep Disorders Research found that in 1989 and 1990, 99 percent of patients with OSA were not diagnosed.(3) Data from 1997 suggest that 95 percent of patients with OSA were not diagnosed.(4) In this issue of American Family Physician, Silverberg and associates(5) note that the diagnosis of OSA is delayed an average of seven years.

OSA occurs frequently in patients with hypertension. As many as one third of essential hypertension cases may be caused by OSA.(6,7) OSA can cause detrimental effects, including a sevenfold increase in motor vehicle crashes caused by somnolence at the wheel.(8) Persons with OSA experience a higher incidence of work-related accidents, poor job performance, depression, family discord, and decreased quality of life than do persons without the sleep disorder.(9)

What role do primary care physicians have in the prevention, diagnosis, and treatment of OSA? First, an awareness of the problem is essential. Primary care physicians can approach OSA by identifying risk factors, focusing on prevention, providing anticipatory guidance, treating comorbidities, and mitigating long-term consequences.

Physicians should systematically include sleep evaluations as part of a complete medical history and physical examination. Risk factors for OSA include obesity, family history of the disorder, smoking, large neck size, recessed chin, a narrowed airway, and male gender. Physicians should be aware that some patients with OSA do not have any of these risk factors.

Patients with OSA may present with excessive daytime sleepiness, loud snoring, dry mouth on waking, chronic nasal obstruction, intellectual dysfunction, social dysfunction, irritability, depression, impotence, or morning headaches.(8-10) The Epworth Sleepiness Scale,(11) a simple screening tool for sleep disorders, may help identify symptoms.

On physical examination, findings may include truncal obesity, recessed chin, oropharyngeal obstruction or narrowing, large neck size (greater than 17 inches in men and 16 inches in women),(10) hypertension, depression, and cardiovascular disease.

Laboratory full-night polysomnography is the gold standard for diagnosing OSA. Geographic unavailability, patient inconvenience, and high cost limit its usefulness.(9) At-home overnight oximetry is used as an alternative to full-night polysomnography. Its advantages include wide availability, in-home use, and relative low cost. However, it has poor sensitivity and specificity.(10)

The goals for treatment of OSA are to reduce morbidity and mortality and to improve quality of life. These goals can be accomplished by preventing the cardiovascular consequences of sleep apnea and by reducing daytime sleepiness, serious unintended injury, stroke, divorce, and occupational dysfunction.(9) Treatment of OSA, which is simple and readily available, can dramatically improve patients' quality of life and prevent many cardiovascular complications such as hypertension and congestive heart failure.

Patients with OSA should be counseled about the potential for motor vehicle crashes, job-related hazards, and impaired judgment. They should be encouraged to lose weight, avoid use of alcohol and sedatives, stop smoking, sleep in the lateral position, and get adequate amounts of sleep.(9)

Continuous positive airway pressure during sleep is often required. Medication and oxygen therapy usually are not beneficial. Dental appliances may be helpful in some patients. In severe cases, surgical intervention may be necessary. The overall success rate for surgery including uvulopalatopharyngoplasty and laser-assisted uvulopalatoplasty is about 40 percent. If present, comorbid conditions such as obesity, hypertension, hypothyroidism, and cardiovascular disease also need to be treated.

Family physicians see patients who are impacted by OSA in their offices daily. Most patients with OSA are not aware that they have this disorder, and it often goes undiagnosed. Results from studies show that educating primary care physicians about OSA results in an eightfold increase in the recognition and treatment of OSA.(4) By educating ourselves and our patients about OSA, we can significantly improve our patients' lives.

For more information, contact the National Center on Sleep Disorders Research at the National Heart, Lung, and Blood Institute Information Center, National Institutes of Health, 6701 Rockledge Dr., MSC 7920, Bethesda, MD 20892-7920, telephone: 301-435-0199 or visit their Web site at http:// index.htm; the American Academy of Sleep Medicine, 6301 Bandel Rd. NW, Rochester, MN 55901, telephone: 507-287-6006 or visit their Web site at; or the American Sleep Apnea Association, 1424 K Street NW, Suite 302, Washington, D.C. 20005, telephone: 202-293-3650 or visit their Web site at http://


(1.) Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;328:1230-5.

(2.) National Heart, Lung and Blood Institute. Fact book: 1983. Bethesda, Maryland: U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, 1984.

(3.) National Heart, Lung, and Blood Institute. Sleep apnea: is your patient at risk? National Institutes of Health, 1995; NIH publication no. 95-3803.

(4.) Ball EM, Simon RD Jr, Tall AA, Banks MB, Nino-Murcia G, Dement WC. Diagnosis and treatment of sleep apnea within the community. The Walla Walla Project. Arch Intern Med 1997;157:419-24.

(5.) Silverberg DS, Oksenberg A. Treating obstructive sleep apnea improves essential hypertension and quality of life. Am Fam Physician 2002;65:229-36.

(6.) Peppard PE, Young T, Palta M, Skatrud J. Prospective study of the association between sleep-disordered breathing and hypertension. N Engl J Med 2000;342:1378-84.

(7.) Nieto FJ, Young TB, Lind BK, Shahar E, Samet JM, Redline S, et al. Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study. JAMA 2000;283:1829-36.

(8.) Findley LJ, Fabrizio M, Thommi G, Suratt PM. Severity of sleep apnea and automobile crashes [Letter]. N Engl J Med 1989;320:868-9.

(9.) Sleep apnea: diagnosis and treatment: a comprehensive teaching curriculum slide set. Retrieved October 2001, from:

(10.) Davies RJ, Stradling JR. The relationship between neck circumference, radiographic pharyngeal anatomy, and the obstructive sleep apnea syndrome. Eur Respir J 1990;3:509-14.

(11.) Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep 1991;14:540-5. n

Benjamin W. Chaska, M.D., is executive vice president and chief medical officer of Park Nicollet Health Services in St. Louis Park, Minn.

Address correspondence to Benjamin W. Chaska, M.D., Park Nicollet Health Services, 6500 Excelsior Blvd., St. Louis Park, MN 55425.

COPYRIGHT 2002 American Academy of Family Physicians
COPYRIGHT 2002 Gale Group

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