SUBJECT: ESSENTIAL HYPERTENSION
STUDENT NUMBER: M00037713
CLINICAL SCIENCES II
Essential hypertension, otherwise known as primary or idiopathic hypertension, is a condition of raised blood pressure with no identifiable cause. Secondary hypertension occurs when blood pressure elevation results from a specific and potentially treatable cause. These include renal diseases, endocrine causes, congenital cardiovascular causes and pregnancy.
This study however, will focus on essential hypertension so as to avoid unnecessary confusion. Blood pressure is relative to each individual and tends to vary markedly depending on height and weight. Levels of blood pressure can also vary depending on the characteristics of the population such as age and ethnic background. (Kumar & Clarke, 2007)
The factors that determine the arterial blood pressure are cardiac output (CO) and peripheral resistance (PR). CO is the amount of blood pumped out of the left ventricle per minute. PR is the amount of friction encountered by the blood as it flows through the lumen of the arteries. (Marieb,2006) It can be increased or decreased by various factors which will be described later.
Blood pressure is recorded in terms of the systolic and diastolic. As blood is pumped through the body, it exerts pressure on the walls of the arteries. The systolic pressure is the pressure against these walls when the heart contracts, and the diastolic pressure is the pressure against the walls when the heart relaxes. (Medline Plus)
A normal blood pressure ranges from 120/70 to 140/85. Any reading which exceeds this range is considered as high, and hypertension id diagnosed when the patient presents with at least three consistent readings above the normal range.
The aetiology of essential hypertension is said to be multifactorial. Genetic factors are contributory as studies show that children of hypertensive parents tend to have a higher blood pressure than age-matched children of people with normal blood pressure. This is partly explainable due to shared environmental influences such as diet and lifestyle. (Kumar & Clarke, 2007)
There is an apparent direct relationship between adult hypertension and low birth weight and poor growth and development in a baby’s first year of life. This may be due to its adaptation to intrauterine undernutrition with long term changes in structure of blood vessels or the function of crucial hormonal systems.
Environmental factors, such as obesity, high alcohol intake, high salt intake, prolonged or recurrent stress, coffee drinking and smoking are among the most significant in elevating blood pressure. The major dangers associated with hypertension are coronary heart disease, cerebrovascular accident (CVA) or stroke, congestive cardiac failure and chronic renal failure.
Hypertension is a common condition in the developed world. It accounts for 95% of cases in the UK. Depending on the criteria of diagnosis, it is present in 20-30% of the adult population. Hypertension rates are much higher in black Africans which involves 40-45% of adults. (Kumar & Clarke, 2007)
32% of men and 30% of women in England aged 16yrs or over have hypertension. In Scotland 33% of men and 28% of women have hypertension. At present there is no comparable data available for Wales and Northern Ireland. However, in Wales15% of adults over 18yrs were reported to have been treated for high blood pressure and in Northern Ireland 19% of men and 27% of women were reported with a diagnosis of hypertension. (Hypertension: the Public Health Burden)
Primary hypertension can be classified in two types. Firstly, benign hypertension where there is a stable rise of blood pressure over many years, and malignant or accelerated hypertension where there is severe elevation of the blood pressure with worsening, over a short period of...