Factors affecting the incidence of hypertension.

The incidence of hypertension was determined among 10,173 patients of general practices in southwestern Ontario studied from 1978 to 1982. For both sexes the incidence of hypertension rose with increasing age. The incidence was higher among men than among women until age 50, after which it was similar for the two sexes. Obesity was positively associated with incidence for both sexes. In men this association diminished significantly with increasing age. The similar trend in women fell just short of statistical significance. In men but not women heavy alcohol consumption was positively related to the incidence of hypertension. However, the broad definition of this variable may have obscured a relation in women. Among men the effect of obesity on the incidence of hypertension was less for heavy drinkers than for light drinkers. Smoking was not related to the incidence of hypertension in either sex.     

Confirming the diagnosis of mild hypertension.

Patients with newly found raised blood pressure are known to have lower pressures at subsequent measurements even when not treated. A study was undertaken to determine the extent to which (a) the number of follow-up measurements and (b) the duration of the intervals between them contributed to this fall in pressure. In 42 general practices 110 patients were identified as having for the first time a diastolic pressure (phase V) greater than 90 and less than 110 mm Hg. Both diastolic and systolic pressures were appreciably lower when measured at return visits when compared with the first measurement. The systolic pressure dropped appreciably in the intervals between the first and the second visits and again between the second and third visits. The diastolic pressure fell appreciably only between the first and second visits. The duration of the interval between visits was not associated with a fall in either systolic or diastolic pressure, but the number of measurements was. This pattern of fall in pressure was not affected by the patient''s age or sex. From these results we conclude that patients with newly identified blood pressures that are mildly raised should be seen at two further visits before a decision about treatment is made. The timing of these follow-up visits is not crucial.     

Glucocorticoid-dependent hypertension.

Glucocorticoid (GC) excess (Cushing's syndrome) is associated with hypertension in at least 70% of patients (in our series 89/130), independently of the subtype (pituitary or adrenal) and the duration, but not of the age of the patients. Cardiovascular damage is quite frequent in hypertensives, but is sometimes also present in normotensives. The mortality of patients with Cushing's syndrome is four times that of the general population when matched for age and sex, and much of this excess mortality is caused by cardiovascular disease. Hypertension remits in most of the patients after successful treatment, but may persist in some. Hypertension also occurs in 20% of patients treated with GC orally. The type of hypertension is independent of salt uptake, can not be controlled by spironolactone but is inhibited by a GC antagonist such as RU486. Experimentally-induced hypertension with oral cortisol (F) is associated with a rise in cardiac output, a fall in calculated total peripheral resistance, an increased forearm vascular responsiveness to exogenous norepinephrine, but no change in overall sympathetic tone, or in norepinephrine reuptake. The increased pressor responsiveness is probably due to local postsynaptic effector mechanisms in the resistance vessels, which could be important in phasic increases in neuronally mediated constrictor responses. Both in patients with Cushing's syndrome and in those on chronic GC treatment, the circadian blood pressure variations are absent or reversed. This may contribute to the deleterious effects of the GC excess on blood vessels. The vascular effects of the GC may be mediated by the activation of specific cardiovascular receptors, by modulating vascular transport systems, or by altered catecholamine or prostaglandin metabolism. GC may also act as mineralocorticoids (MC): in fact type 1 MC receptors are unable, in vitro, to distinguish between aldosterone and cortisol. The specificity-conferring mechanism of typical target organs for MC (e.g. kidney)--is thought to be due to the action of local 11-beta-hydroxysteroid dehydrogenase, which converts F to biologically inactive cortisone (E). When the activity of the enzyme is impaired (syndrome of apparent MC excess, liquorice or carbenoxolone administration), F acts as a MC and MC-hypertension with hypokalemia occurs.(ABSTRACT TRUNCATED AT 400 WORDS)     

Malignant hypertension.

Malignant or accelerated hypertension is a life-threatening disease whose complications may be prevented by rapid reduction of the blood pressure. Diazoxide is presently regarded as the preferred therapeutic agent, but drugs such as trimethaphan, sodium nitroprusside, phenoxybenzamine and hydralazine may be useful in particular situations. Treatment is best carried out in an intensive care unit, where appropriate monitoring and study of the patient can be done. Since the introduction of antihypertensive agents the life expectancy of these patients, even those with renal insufficiency, has increased.     

Perspective on hypertension in the elderly.

More than half of elderly men and women have hypertension, leading to a significant risk of increased morbidity and mortality. The cause of hypertension in this age group is unknown. Left ventricular hypertrophy is frequently present, often associated with diastolic dysfunction. Systolic hypertension in the elderly increases the risk of cardiovascular disease, but there are no good data to show that the treatment of isolated systolic hypertension reduces the morbidity or mortality. Good evidence indicates that antihypertensive treatment in this group decreases cardiovascular morbidity and mortality up to age 80, so most elderly hypertensive patients should be treated. An empiric trial of nonpharmacologic therapy can be initiated in those with mild hypertension and no cardiovascular disease, but most patients will require drug therapy. Most elderly hypertensive patients have accompanying illnesses for which they may or may not be taking medications. Some antihypertensive drugs exacerbate coexisting diseases while others augment treatment regimens. Similarly, drugs may interact in a beneficial or adverse way. Finally, drug metabolism is altered by age, leading to problems with toxicity or diminished efficacy. The choice of medication should be based on all such considerations, including the cost and convenience of the drugs available.