John P. Veinot MD Pathology, Ottawa Hospital, Civic Campus
Hypertension – High blood pressure
Hypertension may be systolic or diastolic. Systolic hypertension is more common in the elderly and is probably related to increased vascular tone.
The components of blood pressure relate to the cardiac output and to total peripheral resistance. These in turn are related to stroke volume and heart rate.
In young hypertensives, cardiac output plays a large contribution towards hypertension whereas vascular resistance plays an increasing role in the elderly.
|Primary – essential – salt, volume, genetic abnormality|
|Secondary – renal, endocrine, drug, vascular, neurogenic and others|
Primary hypertension, the common type, usually occurs in middle age people, is moderate, has a gradual onset, is not associated with physical findings and has a strong family history.
Secondary hypertension may occur in young people, even children. It tends to be severe, sudden onset and associated with physical findings. Family history may be present in rare cases but is not common.
Primary hypertension relates to a genetic abnormality in vascular tone, or in the absorption or excretion of sodium and calcium. It should be remembered that the kidney plays an important role in hypertension with the renin angiotensin system.
Pressure receptors in the blood vessels, and the brain and nervous system regulation of vascular tone are also important.
Secondary Hypertension: This is important as many causes may be treated and the hypertension may be cured. Common causes include:
|Renal disease – glomerulonephritis, chronic renal failure, renal artery stenosis, and renin producing tumours|
Vascular related renal atrophy
|Endocrine/drug – pheochromocytoma, adrenal cortical hyperplasia or tumors, thyroid disease, or birth control pill|
Pheochromocytoma- an adrenal tumor
|Vascular causes – aortic insufficiency and aortic coarctation|
|Neurogenic – spinal cord trauma/transection, increased intracranial pressure|
Hypertension enhances other cardiovascular disease and is risk major factor for sudden death and atherosclerosis. Complications of hypertension affect the small vessels with scarring and microaneurysms and the large vessels with vascular ectasia, aneurysms, dissection and vascular rupture.
The organs involve include the:
|Eyes - microaneurysms, papilledema (raised intracranial pressure)|
|Heart – left ventricular hypertrophy, myocardial infarct, congestive heart failure|
|Brain – raised intracranial pressure, cerebral hemorrhages|
|Blood vessels – atherosclerosis, aneurysms|
|Kidney – acute renal failure, chronic renal failure|
This is severe accelerated hypertension, often associated with a sudden hypertensive crisis with diastolic blood pressure greater than 130 mm of mercury. It is rare and may relate to a coagulation disturbance. It causes renal failure, encephalopathy, myocardial failure and intravascular coagulation.
Artery with changes of maligant hypertension ; more arterial changes of malignant hypertension