HYPERTENSION
Past Tense, Present Sense

By V K VERMA

There is adequate evidence to show that adult hypertension begins to “evolve'” during the first twenty years of life.

The testimony is also quite clear just as well: genetic and environmental factors influence blood pressure during childhood. This, in turn, may encourage the development of essential hypertension as one “comes of age.“

Hypertension is the commonest problem facing man at present. Though the understanding of hypertension has improved considerably with an increased awareness of the disorder in the general population, the control of hypertension has been dismally poor.

Reports suggest that only 27 per cent of hypertensives are adequately controlled even in the most developed countries, despite their advanced healthcare systems.

The major burden of hypertension complications arises not from the few with severe hypertension, but from those with mild hypertension.

Despite continued efforts hypertension will almost never be conquered because it is one of those diseases as a “The Lancet” editor, put it, "[That] afflict us from the middle age onwards [that] might simply represent unfavourable genes that have accumulated to express themselves in the second-half of our lives. This could never be corrected by any evolutionary pressure since such pressures act only during the first-half of our lives: once we have reproduced, it does not greatly matter that we grow 'sans teeth, sans eyes, sans taste, sans everything.’”

New studies have found that blood pressure levels often equate with low birth weight, body mass, maternal age, racial factors, childhood obesity, insulin levels, an elevated blood pressure during childhood, and a positive family history. As a matter of fact, children from hypertensive families generally tend to have higher blood pressure levels than kids from normotensive families. Besides, there is also a greater association in blood pressure levels between fathers and their children.

Aside from this, there are also superimposed environmental factors like stress, excess salt and mineral intake, alcohol, smoking, sedentary lifestyle, caffeine, temperatures, altitude, exposure to drugs with pressor, or nephrotoxic, properties, that lead to the hypertensive state.

Measurable End-Product

"Blood pressure," as one authority put it, "is a measurable end-product of an exceedingly complex series of factors, including those which control vessel calibre and responsiveness -- those which control fluid volume both within and outside the vascular compartment; and, those which control cardiac output. None of these factors are independent; they interact with each other and also respond to changes in blood pressure. It is not easy, therefore, to dissect both the cause and effect.

Some factors which play a role in cardiovascular control are completely normal in hypertension; indeed, normality would require some explanation as it would indicate lack of responsiveness to increased pressure. However this maybe, normal blood pressure, especially during the first two decades of life, is defined as systolic and diastolic blood pressure below the 90th percentile of distribution, both for age and sex. In other words, hypertension may be characterised as systolic, or diastolic, pressure greater than the 95th percentile.

In adults, a blood pressure of 120/80 mm Hg is considered optimal; a blood pressure of 130/85 mm Hg as normal, and any blood pressure more than 140/90 mm Hg as high. The variability of blood pressure measurements, both on a single visit and on separate occasions is much greater than realised.

As Perry and Miller conclude: "Perhaps, only one-third to two-third of people whose measured diastolic pressures exceed 95 mm Hg on a single occasion actually have average pressures that high… In the general population, single measurements of diastolic pressure exceed 95 mm Hg in approximately equal numbers of normotensive, borderline and hypertensive patients. Be that as it may, hypertension should be diagnosed only after elevated blood pressure is recorded, and confirmed, on at least three separate/consecutive examinations one week apart. At each of the occasions, blood pressure should be measured at least twice, and if the readings are >5 mm Hg apart, more readings are necessary.

Guidelines

Among a host of guidelines recommended when measuring blood pressure, while using a standard sphygmomanometer, the following pointers may be consequential:

1. Initial readings should be taken after five minutes in supine position, immediately on and after two minutes on standing. For routine follow-up, measurements can be taken with the patient sitting in a chair with a back-rest.
2. Never exert pressure through the stethoscope during an examination; it may lower diastolic readings.
3. Note both the fourth [muffling] and fifth [disappearance] of Korotkoff's sounds; many confreres acknowledge the fifth sound to be diastolic.
4. Cuff should be of proper fit. False, or elevated, levels may be obtained if the cuff is too small; if it is too large, false low blood pressure recordings are recorded
5. Measure the blood pressure in both the arms initially and use the arm with higher BP for all future readings
6. Blood pressure readings should be taken by age three, and yearly thereafter
7. Regular ausculation methods are not viable in infants, or very young children, because of problems related to non-co-operation and apprehension, what with [the] Korotkoff's sounds being softer. Electronic, or automated, ultrasound devices are both useful and reliable.

Table: 95th Percentile of Blood Pressure

Diagnosis

A secondary cause is found in 50 per cent of infants with hypertension. Umbilical artery catheterisation, intraventricular haemorrhage, patent ductus arteriosus, bronchopulmonary dysplasia are significant risk factors. Among children in the 1-10 age group, an underlying cause may frequently be related to renal disease, vascular disease [coarctation or renal artery stenosis], albeit there are a number of other less common causes.

Yes, primary hypertension remains the most common cause in all age groups -- infants, children, and adults. Also, a secondary cause of hypertension may often be related directly to the level of blood pressure, and conversely to the age of the patient. Mild elevations [>95th percentile] may not, in general, be associated with secondary disease.

Primary hypertension in childhood and adolescence -- as in adults -- is usually asymptomatic, and often detected during routine physical examination. The most frequent symptom is usually a headache. Symptoms like seizures, nosebleed, dizziness, and syncope usually indicate severe secondary hypertension, or concomitant use of vasopressor agents, or emotional crises.

Hypertension may also present as acute distress in infants with signs and/or symptoms of congestive heart failure, justifying aggressive treatment rather than diagnosis. Such patients may be reviewed by way of screening studies:

• Haematocrit, S electrolytes, S lipid levels, blood urea nitrogen, creatinine, urinalysis, and renal ultrasonography, especially during the initial evaluation.
• History and physical examination usually reveal evidence of a secondary cause of hypertension; hence, detailed studies without such evidence are not usually warranted.
• In prepubertal children, aside from the review cited, aggressive attempts must be made to rule out the most common secondary causes sequentially. In infants, due to the poor general condition in which they usually present, treatment takes precedence over diagnosis and invasive diagnostic studies should be postponed till the infant is stable, normotensive, and larger.

Therapy

The aim of any treatment plan is to reduce blood pressure to a level much below the 95th percentile for age. In adults, the target BP is 130/85 mm Hg, or lower. As in adults, the risk factor stratification for cardiovascular disease is equally important in children. Management of primary hypertension, in young children and adolescents, without pharmacological intervention, is often effective, probably more so. Most children with early essential hypertension respond to weight control, diet, exercise, and stress-control measures. It is also appropriate to reduce salt intake especially in patients with primary hypertension, because they are often salt-sensitive.

In addition, a hypertensive child, or teenage athlete, should be asked to undergo formal exercise testing to decipher if the blood pressure peak is so high that pharmacological treatment is indicated. If exercise levels reveal a systolic elevation [>210 mm Hg], or high diastolic increase, drug therapy may be recommended. Children should be recommended to participate in sports involving dynamic exercises; isometric exercises should be curtailed. Besides, drug therapy needs to be initiated if non-pharmacological management gives no benefit, or the patient has additional risk factors for cardiovascular disease [CVD].

Pharmacological therapy today includes a large number of drugs available in our armamentarium: diuretics, beta-blockers, calcium channel blockers, alpha-blockers, ACEIs, and angiotensin-II receptor blockers. Each of these drugs has its indication and side-effect profile and they allow us to individualise therapy from patient to patient. The older drugs, such as the centrally-acting alpha blockers, sympathetic blockers and peripheral vasodilators are rarely used today. The preference is towards drugs which can be given once a day to improve compliance, smoother and more persistent control, lower cost, protect people from sudden death, heart attack, and stroke, due to sudden rise/s in blood pressure after arising from overnight sleep. Combination of low doses of two drugs, of different classes, have been shown to provide additional benefit with fewer side-effects.

Conclusion

In [high] blood pressure that has been well-controlled for at least one year, an attempt must be made to decrease the number and doses of drugs in a slow, progressive and controlled manner with close watch and follow-up. This is effective only in patients who are also following modification/s, or are young with mild hypertension, and easily controlled on a single drug. The rest would probably require drugs all through life.

As Kaplan observes, "The main underlying problem is the asymptomatic nature of hypertension which requires a lifetime of therapy but provides no immediate, or complete, benefit and often introduces bothersome side-effects and considerable financial costs. We and our patients would be more likely to achieve better success if untreated hypertension hurt, not a great deal but just enough, to remind the patient of the need to take medicines… to obtain relief."