HYPERTENSION
Blood pressure like height and weight is a biological characteristic of an individual and shows interindividual variability. Hypertension is a condition in which the patient has high blood pressure than judged to be normal.
Classification :
The raised blood pressure can be found in various conditions.
(1) Temperary : Symptamatic hypertension occures during exercise emotional, disturbances. Also can be seen in acute attacks of gout.
(2) Paroxysmal : It is due to tumor of suprarenal medula (Phacochromocytoma)
(3) Persistent hypertension : It is a clinical entity.
It can be divided in 2 according to aetiology.
(a) Primary (2) Secondary
SECONDARY HYPERTENSION
The hypertension secondary to renal, vascular, endocrine lesion
(1) Renal Cause of Secondary HT
(a) Chronic Diffuse glomerulonephritis
(b) Pyelonephritis
(c) Polycystic kidnees
(d) Diabetic nephropathy
(e) Renovascular disease
(2) Endocrine Cause
(a) Cushings syndrome
(b) Pheochromocytoma
(c) Primary hyper aldesternism
(3) Vascular Causes
(a) Renal artery disease
(b) Coarcation of aorta
(4) Other
(a) alcohol
(b) Drugs
(c) Pregnancy.
But the for the present study essential hypertension is only taken in account
ESSENTIAL HYPERTENSION
In 90% of patient with hypertension although some mechanisms may be operating it is not possible to define a specific underlying cause and they are said to have essential hypertension.
Synonyms : (1) Primary hypertention
(2) Idiopathic hypertension
(3) Hyperpeisia (Sir clifford Albutt)
Definition :
Essential hypertension is defined as sustained high blood pressure not attributable to a single cause but reflecting the interaction of multiple genetic and environmental influence.
Prevalence :
The prevalence rate of HT increases with age and higher in blacks than in whites.
HT is more common in men than in women upto the age 50 yrs. after which in is more common in women.
E.H.T. is especially frequent in some race particularly American blacks and Japanese and commoner in carries where there is high salt intake.
Thus the causes can be divided as :
(1) Genetic
(2) Environmental
(3) Other Disease Related
The Etiological Factors
Genetic :
(1) The influence of genetic factors contribute about 30% blood pressure variation.
(2) The inheritance is multifactorial and of heterogeneous nature.
(3) The genes that contribute to human essential HT have not been identified, but both monogenic defects (e.g. glucocorticoid remediable aldesternism and Liddles syndrome) and susceptibility genes (e.g. angeotensinogengene) have been now reported which have as one of their consequences an increased acture pressure.
Environmental Factors :
(1) Nutrition :
Several component of diet may change blood pressure. Some important facts are related with this:-
(a) The maternal malnutrition may be an important cause of HT Some studies have shown that the subject with the lower birth weightt and higher placental weight, have higher blood pressure in middle age.
(b) Vegetarians have lower blood pressure at all ages than omnivorous one possibility is that unsaturated vegetable fat lowers blood pressure.
(c) A number of studies have shown a positive association between Na intake and BP and a negative association between potassium intake and BP, but on current evidence the contribution of excessive sodium intake or inadequate potassium intake on HT in western society is small.
(2) Habits - HT
(1) Alcohol intake :
High alcohol intake (more than 6 units a day) have been shown to be associated with elevated BP in large number of studies.
(2) Smoking :
Nicotine and carbon monoxide the two major products of tobacco combustion are both potent vasoconstrictors. Nicotine also stimulates increase secretion of catecholamines, Tobacco smoking is well known to cause an acute rise in BP but whether prolonged smoking leads to sustained HT has not been so well established.
Stress :
D Exposure to a prolonged emotional stress and type-A personality are said to cause or aggravate high BP.
D Acute pain, tension, mental stress produces significant rise in BP.
D Chronic job strains leads to progressive increase in blood pressure.
D Modern City life, worry, anxiety and prolonged mental strain especially when combined with sleeplessness and lack of regular exercise are the general causes of HT.
Other Diseases And H T Relation
(1) Obesity :
High BP is associated with a high body mass index. Mainly central, obesity correlates well with BP than overall body mass the association with BP may reflect humoral factors and perhaps genetic linkage.
(2) Diabetes Mellitus:
Diabetics tend to have higher prevalence of atherosclesosis and HT. Insulin resistance or insulinemia have been suggested as being responsible for the increased Arterial pressure. Insulin resistance is common in patients with non insulin dependant. DM (NIDDM).
(3) Gout and Osteoarthritis:
These are also, often associated with HT.
(4) At the climacteric or after removal of both ovaries HT is seen, the associated rapid gain in weight is an important causal factor.
(5) Chronic lead poisoning is exogenous ... raised serum lipids HT. associated with raised and lipid ........... much higher risk of C.V.S. complication.
