Hypertension is persistent elevation of blood pressure above normal values on three different occasions under mental & physical rest.
Blood pressure> 140/90 is diagnosed as hypertension .
A. Causes of isolated Systolic Hypertension
- Atherosclerosis. - AI-PDA
- Thyrotoxicosis. - Coarctation of Aorta .
- Complete heart block. - Anxiety, fever.
B. Causes of Dyastolic Hypertension
This is usually associated with elevated systolic blood pressure .
I. Primary hypertension "Essential"
- Age : usually between 35 - 55 years.
- No apparent cause .
- Family history is usually positive.
It is usually benign hypertension in most cases (slowly progressive with remote complications), but it may turn malignant .
Theories of primary hypertension:
1. Renal Theory: There is increase of renin secretion.
2. Increased adrenal gland activity --> increased Aldosterone secretion.
3. Increased activity of VMC --> ++ sympathetic discharge --> ++ Blood pressure .
4. Multifactorial theory:
5. Barroreceptors resetting.
6. Impaired pressure natriuresis.
8. Genetic factors, hypertension tends to run in families and children of hypertensive parents.
9. Insulin resistance, obesity.
10. Alcohol intake, excessive sodium intake or salt sensitivity.
II. Secondary hypertension
- Age: usually < 35 or > 55 years.
- Causes: e.g renal or endocrinal diseases.
- Family history is usually negative.
It may be malignant hypertension (rapidly progressive with early complications) specially with renal hypertension.
Causes of secondary hypertension:
Glomerulonephritis, Chronic tubulointerstitial nephritis, Diabetic nephropathy, Obstructive uropathy, Renal artery stenosis, Polycystic kidney disease.
2. Endocrinal :
- Cushing syndrome and Conn's disease .
- Pheochromocytoma, Acromegally.
- Hyperparathyroidism, Myxodema.
Increased intracranial tension leads to increase in blood pressure (cushing reflex).
4. Cardiovascular: Coarctation of aorta.
5. Pregnancy: Preeclampsia.
6. Blood disease:
Polycythemia -- > hyperviscocity --> increase in blood pressure .
Corticosteroids, Oral contraceptives containing oestrogen, NSAID, Ephedrine, Erythropiotin, Cyclosporine,Carbenoxolone and Sympathomimetic agents.