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MEDICAL TOPICS- HIGH BLOOD PRESSURE

Hypertension


Summary

Description

  •  HIGH  BLOOD PRESSURE  is known in medicine as Hypertension. It is defined as a systolic blood pressure of at least 140mmHg and/or a diastolic blood pressure of at least 90mmHg in adults. It is an important risk factor for subsequent cardiovascular disease
  • Systolic blood pressure of 120-139mmHg or a diastolic blood pressure of 80-89mmHg in adult patients should be considered prehypertensive. These patients require counseling about health-promoting lifestyle changes to prevent or delay the onset of hypertension, and should be followed at least annually
  • Approx. 90% of cases of hypertension have no identifiable cause, and uncomplicated essential hypertension is asymptomatic
  • Preoperative hypertension is associated with significant increases in perioperative morbidity and mortality, but it is unknown whether the preoperative treatment of hypertension lowers the risk
  • Hypertension in children and adolescents is increasingly recognized. Approx. 5% of children and adolescents have essential hypertension. Blood pressure measurements should begin in children at 3 years of age. Hypertension is defined as a systolic blood pressure equal to or >95th percentile value for gender, age, and height. Those in the 90th percentile are considered prehypertensive. In adolescents, a blood pressure >120/80mmHg should be considered prehypertensive

Immediate action

Treatment should be started immediately if blood pressure is extremely high, there is optic disc edema in the  retinal of the eye, or if there is evidence of rapidly progressive end-organ damage- like stroke or heart attack or kidney damage

Urgent action

Hypertension should be treated urgently and aggressively in the following emergencies:

Key points

  • Blood pressure tends to rise with age
  • All definitions of hypertension depend on two or more blood pressure readings taken at each of two or more visits after initial screening
  • Hypertension is defined as systolic if the blood pressure is >139mmHg and/or diastolic if the blood pressure is >89mmHg in adults, or if the blood pressure is >95th percentile value for age, sex, and weight in children
  • Stage 1 hypertension is defined as a systolic blood pressure of 140-159mmHg and a diastolic blood pressure of 90-99mmHg; stage 2 hypertension is defined as a systolic blood pressure greater or equal to 160mmHg, or a diastolic blood pressure greater or equal to 100mmHg
  • Prehypertension is defined as systolic if the blood pressure is between 120-139mmHg, and/or diastolic if the blood pressure is between 80-89mmHg in adults, and if the blood pressure is between the 90th and the 95th percentile values in children
  • In 90% of hypertension cases, there is no identifiable cause (termed 'essential hypertension'). There are no symptoms of raised blood pressure - only those attributable to target organ damage
  • Hypertension is an important risk factor for cardiovascular disease and stroke. Treatment is effective in reducing the risk. In some patients, only changes in lifestyle are required. Many patients can be adequately controlled on first-line treatments, such as diuretics and beta-blockers, while other patients need additional agents, often in combination

Background

Cardinal features

  • Hypertension is defined as a systolic blood pressure of at least 140mmHg and/or a diastolic blood pressure of at least 90mmHg
  • Approx. 10% of hypertensive patients have an identifiable cause for their hypertension, but finding an underlying cause presents an opportunity to 'cure' the hypertension and not merely to treat or control it
  • In the remaining 90% of patients, hypertension is idiopathic (essential hypertension)
  • Uncomplicated essential hypertension is asymptomatic
  • Untreated hypertension is a risk factor for the development of subsequent cardiovascular disease
  • Successful treatment of hypertension reduces the risk of cardiovascular disease

Causes

Common causes

Approx. 90% of cases of hypertension have no identifiable cause (so-called primary or essential hypertension).

Rare causes

The ABCDE mnemonic can be used to help remember potential causes of secondary hypertension.

A:

  • Accuracy of diagnosis
  • Obstructive sleep apnea
  • Aldosteronism - may be more common than originally thought. It has been indicated that 20% of patients with hypertension that is resistant to treatment may have primary aldosteronism

B:

  • Presence of renal artery bruits suggestive of renal artery stenosis (narrowing), renovascular hypertension
  • Bad kidneys (renal parenchymal disease)

C:

D:

  • Drugs, e.g. birth control pills
  • Diet, e.g. excess salt 

E:

Contributory or predisposing factors

  • Increasing age
  • Obesity
  • Physical inactivity
  • Excessive alcohol consumption
  • Smoking
  • Diabetes mellitus
  • Long-term risk of developing hypertension is also increased in people who exhibit time urgency or impatient behavior and/or hostility

Epidemiology

Incidence and prevalence

Prevalence

Approx. 25,000 cases per 100,000 of population.

Frequency

In the US, approx. 43 million people were estimated to have hypertension in 1991.

Demographics

Age
  • Prevalence increases with age, but occurs in up to 2% of young adults
  • Prevalence is >50% in people >60 years of age
  • Secondary hypertension is more common in children, but approx. 5% of children and adolescents are believed to have essential hypertension

Gender
  • In young and middle-aged people, hypertension is more common in men vs women
  • Prevalence of hypertension increases more steeply with age in women vs men, and elderly women are at least as likely to be hypertensive as elderly men

Race
  • More common in African-Americans than in Caucasians
  • Rates of good blood pressure control in the US are lowest in Mexican Americans and Native Americans

Genetics

A family history of hypertension is associated with an increased risk of developing the disorder.

Socioeconomic status

Prevalence of hypertension is greater in lower socioeconomic groups.