Hypertension

Introduction

Arterial hypertension, or high blood pressure is a medical condition where the blood pressure is chronically elevated. Normal blood pressure is below 120/80; blood pressure between 120/80 and 139/89 is called ‘‘pre-hypertension’’, and a blood pressure of 140/90 or above measured on both arms at two instances (several weeks apart) is considered high blood pressure. The complications of hypertension are often referred to as end-organ damage because damage to these organs is the end result of chronic high blood pressure. Uncontrolled hypertension can cause strokes, which can lead to brain or neurological damage. The strokes are usually due to a hemorrhage or a thrombosis of the blood vessels that supply blood to the brain. The patient's symptoms and signs are evaluated to assess the neurological damage. A stroke can cause weakness, tingling, or paralysis of the arms or legs and difficulties with speech or vision. Multiple small strokes can lead to dementia. The best prevention for this complication of hypertension or, for that matter, for any of the complications, is control of the blood pressure.

Epidemiology

The level of blood pressure regarded as deleterious has been revised down during years of epidemiological studies. A widely quoted and important series of such studies is the Framingham Heart Study carried out in an American town: Framingham, Massachusetts. The results from Framingham and of similar work in Busselton, Western Australia have been widely applied. To the extent that people are similar this seems reasonable, but there are known to be genetic variations in the most effective drugs for particular sub-populations.

High blood pressure does not mean excessive emotional tension, although emotional tension and stress can temporarily increase the blood pressure. While chronic anxiety is associated with poor outcomes in people with hypertension, it alone does not cause it.

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Prevalence

Cardiovascular diseases (CVD), most of which are due to atherosclerosis (mainly heart attack and stroke) and often related to arterial hypertension (AH), are responsible for nearly 20% of all deaths world-wide (nearly 10 million). They are the principal cause of death in all developed countries accounting for 50% of all deaths and are also emerging as a prominent public health problem in developing countries, ranking third with nearly 16% of all deaths. It is known that more than 95 % of hypertensive patients in the community are of essential or idiopathic/unknown aetiology, and only a small percentage have an identifiable cause (secondary hypertension).

Essential hypertension affects approximately 75 million Americans, almost 1 in 4 adults in the United States. It is thus a major public health problem. African American patients with poorly controlled hypertension are at a higher risk than Caucasians for most end-organ damage and particularly kidney damage. These differentials are more pronounced in young adult women. Among the very old, race differentials in hypertension prevalence rates are less pronounced. The reasons for the epidemic hypertension rates in the United States are largely environmental: Obesity and physical inactivity probably account for a significant proportion of the premature excess hypertension in African Americans relative to white women.

According to a recent survey, 1.0% of the adult American population use complementary and alternative medicine to treat hypertension.

Age

Mean systolic and diastolic blood pressure and prevalence of AH increase with age throughout childhood, adolescence and adulthood in most populations of developed and developing countries. However, in some isolated populations, this age-related rise of blood pressure (BP) is not evident.

Sex/gender

Men tend to display higher blood pressure than women, more evident in youth and middle-age. Later in life (over 50 years old), the difference narrows and the pattern may be reversed.

Heredity

Although the precise mode of heredity/inheritance has not yet been demonstrated, a high occurrence of hypertension is observed among subjects with a family history of hypertension and it is higher and more severe when both parents are concerned.

Ethnicity/race

Studies have also revealed higher blood pressure levels in the black community than in other ethnic groups, mainly in black Afro-Americans with early onset, severity and appearance of complications.