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Hypertension

• The sphygmomanometer became available at the turn of the century.

• The Veterans Administration study established that anti-hypertensive treatment offers protection against some of the complications of hypertension notably, the incidence of stroke, renal and congestive heart failure but not coronary artery disease.

• Blood pressure is a continuous variable and this situation has resulted in an inevitable continuous debate over borderline readings. Even casually elevated values may be associated with increased cardiovascular morbidity.

• The risks of death and disability are increased only in the broad statistical sense, a large majority of patients with elevated blood pressures live lives of normal longevity and health. Hypertension is a risk factor and does not inevitably lead to complications. 

• Only a minority of hypertensive patients experience a vascular calamity, whereas many people with normal blood pressure and thus without the risk factor can still suffer from cardiovascular events. Indeed, most cardiovascular events probably occur in individuals with normal blood pressure because more people are normotensive than hypertensive.

What is the Prevalence of Hypertension?

Eighteen per cent (18%) of the population is affected with hypertension when 160/95 is used as the cutoff for the diagnosis of hypertension. A higher prevalence of  38% of the population is  affected when 140/90 is used as the cutoff. The frequency of high blood pressure increases with age. At every age, high blood pressure is more common in blacks than whites. Blacks are more predisposed to the vascular damage induced by the hypertension.

What is the cause of hypertension?

No one knows exactly, but genetic factors are important. There is a strong familial aggregation for blood pressure strata which may be genetic or environmental. Human studies indicate that 20% to 40% of the population variance in blood pressure is genetically determined. The variation in blood pressure is due to the combined effects of multiple genes, with estimates of the number of relevant genes ranging from approximately five to 20.

What are the Complications of Hypertension?

·        Coronary artery disease and congestive heart failure

·        Renal Failure

·        Stroke

·        Atherosclerosis

What are the various patterns of Blood pressure elevation?

·        Systolic hypertension

Occurs in the elderly and may be a manifestation of atherosclerosis and decreased arterial elasticity. Systolic hypertension may also occur as part of a hyperdynamic cardiovascular state such as that occurring in hyperthyroidism or in younger people who appear to have increased beta adrenergic activity.

·        Labile hypertension

Is an intermittent type of hypertension

·        Borderline hypertension

These represent blood pressure reading in the upper limit of normal

·        Diastolic hypertension

If persistent and severe, it may result in hypertensive vascular disease.

·        Malignant hypertension

Characterized clinically by severe accelerating hypertension with retinopathy, Papilledema and evidence of renal or other end organ damage. Pathologically it is characterized by fibrinoid necrotizing arteritis.

May occur de novo or may follows pre existing milder forms of hypertension or as a complication of essential hypertension or of secondary hypertension, with the notable exception of coarctation of the aorta, a condition in which the renal circulation is protected from the high pressures that occur proximal to the coarctation.

What are the Benefits of the treatment of hypertension?

By treating hypertension you would Improve the cardiovascular morbidity and mortality associated with elevated blood pressure.

How about Dietary sodium and High Blood Pressure?

Sodium deprivation can greatly improve high blood pressure in certain subgroups but the evidence so far does not support the blanket recommendation of sodium deprivation for all hypertensive patients.

The Intersalt study found no correlation between sodium intake and blood pressure in 48 centers around the world. In addition there is even less reason to believe that sodium deprivation of normal people would prevent the occurrence of hypertensive disease.

What are the Goals of the initial evaluation of patients with hypertension?

• Establish the diagnosis of sustained hypertension

• Define coexisting disease

• Characterize other risk factors

• Identify the presence and extent of target organ damage

• Identify curable forms of hypertension

What is the Diagnostic workup of Hypertension?

• Complete Blood Count

• Urinalysis

• Electrolytes profile

• Electrocardiogram

• Echocardiogram

• Lipid profile

What are the changes due to hypertension which are seen on examination of the Fundus of the eye?

Depending on the severity of the vascular changes seen on eye examination the following may be seen 

·        grade 0

Normal

·        Grade I

Copper or silver wire appearance of the arterioles related to spasm, with some tortuosity and perhaps segmental constriction

·        Grade II

Arteriovenous nicking, generalized or local focal spasm

·        Grade III

Overt hemorrhage or exudates

·        Grade IV

Papilledema which is swelling of the optic disk, in addition to the above changes. This is a serious complication of hypertension and can result in loss of vision if untreated.

What are the major Anti-hypertensive medications available?

Medications used for treatment of hypertension belong to a number of drug groups which include the following

·        Diuretics

These drugs lower the blood pressure by increasing salt excretion by the kidney.

·        Central acting agents

These drugs lower the blood pressure by decreasing the sympathetic tone, which causes relaxation of the blood vessels and thus lower the blood pressure.

·        Peripheral vasodialtors

These drugs directly lower the tone of the blood vessels and thus cause blood vessel relaxation and lower blood pressure

·        Beta blockers

Lower the blood pressure by a number of mechanisms including blood vessel relaxation and lower cardiac output

·        ACE inhibitors

These relatively new agents are very beneficial, they lower the blood pressure by decreasing the level of a hormone called angiotensin II. They also increase the concentration of a number of substances which cause vasodilatation.

What are the major side effects of ACE inhibitors?

·        Hypotension

·        Hyperkalemia

·        Cough

·        Angioedema

·        Renal failure

·        Hypersensitivity reactions

·        Proteinuria

Angiotensin Receptor Antagonist

Similar to ACE inhibitors but work directly by blocking the receptor for angiotensin. Have less side effects. Example Losartan (Cozaar))

 
What are the advantages of ACE inhibitors?

·      Prolong survival of patients with CHF

·      Preserve renal function

·      Little effect on plasma lipid concentration

·      Cannot be used in pregnancy

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Last updated Saturday, September 16, 2000