The natural history of blood pressure in childhood

To find out whether there is a relationship between the level of blood pressure in childhood and later on in life, and whether future hypertensives can be identified early in life, we selected a random sample of 596 Dutch children. At the first examination they were 5-19 years of age. In 386 of them (65%) at least five consecutive annual blood pressure measurements were made between 1975 and 1982. The stability of a child's position in the blood pressure distribution ('tracking') was studied by linear regression of follow-up blood pressure on initial blood pressure. 'Tracking' coefficients were 0.4 to 0.6 mmHg/mmHg for systolic pressure, and 0.2 to 0.5 mmHg/mmHg for diastolic pressure after four years of follow-up. Twenty-seven per cent of the boys and 44% of the girls who were in the upper 10% of the systolic blood pressure distribution at the first examination were still there after four years. For diastolic pressure these figures were 25% and 22%, respectively. These observations indicate that there is a moderate degree of blood pressure 'tracking' in childhood. They further imply that it is impossible to detect future hypertensives early in life by measurement of blood pressure only.

Distributions and determinants of total and high-density lipoprotein cholesterol in Dutch children and young adults

Serum total cholesterol and its putative determinants were measured in 5,089 subjects, ages 5-30 years, comprising 76% of the total population of two districts of the Dutch town of Zoetermeer. From this group, 596 subjects, ages 5-19 years, were randomly selected, and distributions and determinants of high-density lipoprotein (HDL) cholesterol were studied in 458 of them. The variables studied included body weight; Quetelet index; menarche; parental cholesterol; physical activity; consumption of coffee, alcohol, and tobacco; and use of oral contraceptives. Mean total cholesterol levels showed a decrease in both boys and girls between the ages of 10 and 16 years. Mean HDL cholesterol levels remained the same until the age of 17, after which they showed an increase for females and a decrease for males. Total cholesterol was associated with age, body weight (in those older than 15 years), and parental cholesterol concentrations. For HDL cholesterol, the most important determinants were gender, age, and body weight (the latter only for males 15 years and older). These findings suggest that during growth and maturation the determinants of serum cholesterol differ from those later on in life.

Acute hemodynamic and antiischemic effects of intravenous amiodarone

The acute hemodynamic and antiischemic properties of amiodarone were investigated in 16 patients with more than 70% diameter reduction of a left coronary artery. Two successive atrial pacing stress tests (APST I and II) were performed, with an interval of 40 minutes in between, and amiodarone, 5 mg/kg/5 min, was infused 30 minutes after APST I. Hemodynamic changes during amiodarone administration consisted of a 20% decrease in left ventricular (LV) systolic pressure, a 13% decrease in systemic vascular resistance and an 18% decrease in stroke work. Coronary vascular resistance was reduced 19% and coronary sinus flow increased 23%. Despite a secondary 14% increase in heart rate, contractility decreased 21%, accompanied by a 45% increase in LV end-diastolic pressure, which persisted until APST II. Although most hemodynamic changes were observed only during the infusion, contractility and LV systolic pressure were still diminished at the beginning of APST II and remained so during pacing, resulting in a reduction in myocardial oxygen demand compared to APST I. Although overall myocardial oxygen consumption and coronary flow were equal during both pacing tests, amiodarone significantly reduced pacing-induced myocardial ischemia. Lactate metabolism remained normal during APST II (lactate extraction 12 +/- 3% vs -28 +/- 8% (APST I) at maximal pacing rates [p less than 0.05]), while ST-segment depression, LV end-diastolic pressure postpacing and angina were also significantly reduced during APST II. Thus, in humans, intravenous amiodarone reduces vascular resistance and contractility and inhibits pacing-induced myocardial ischemia, presumably by reducing myocardial oxygen demand.

Blood pressure and immunoglobulins

Serum concentrations of IgG and IgM were measured in 87 hypertensive and 87 normotensive subjects, matched for age and gender, and selected from the same general population. No significant differences between these two groups were found, in contrast to some previous reports. The reasons for this discrepancy are discussed.

Does change in blood pressure predict heart disease?

Whether a change in blood pressure is related to the occurrence of cardiovascular disease, independent of blood pressure level, was investigated using data collected in the Framingham heart study on 5209 subjects. The follow up period of 26 years was divided into a first period of 12 years in which the blood pressure change was computed for each individual and a subsequent period of 14 years in which the risk of cardiovascular disease was determined. Blood pressure change was positively related to risk of cardiovascular disease. This association remained when blood pressure level at the start of the study was taken into account but disappeared when the level attained after the first 12 years was taken into consideration. For the clinician this suggests that the decision to treat high blood pressure is best guided by the actual level of pressure and not by its long term trend in the past.

A randomized trial of sodium intake and blood pressure in newborn infants

We studied the effect of dietary sodium on BP in a double-blind randomized trial with 245 newborn infants assigned to a normal-sodium diet and 231 to a low-sodium diet during the first six months of life. The sodium intake of the normal-sodium group was almost three times that of the low-sodium group. Systolic BP was measured every month from the first week until the 25th week. At 25 weeks, systolic pressure was 2.1 mm Hg lower in the low-sodium group than in the normal-sodium group. The difference between the groups increased significantly during the first six months of life. These observations are in agreement with the view that sodium intake is causally related to BP level.

Determinants of change in blood pressure during childhood

The determinants of change in blood pressure during childhood were studied in 596 Dutch children, aged 5-19 years. The children were randomly selected from a general population in Zoetermeer, near the Hague, the Netherlands, and this report deals with 462 children (78%), who had three to seven annual measurements of blood pressure between 1975 and 1982. The rate of change in blood pressure was obtained by least-squares regression of blood pressure on time for each subject. Initial level of blood pressure was associated negatively with subsequent change in systolic and diastolic pressure, even after adjustment for regression toward the mean. Parental blood pressure and initial body weight were related positively, but weakly, to the rate of blood pressure change. Initial serum uric acid was associated positively with change in blood pressure in girls only. Vascular reactivity, as measured by the cold pressor test, was not related to the rate of change in blood pressure. The same applied to pulse rate and the use of tobacco, coffee, and oral contraceptives. The finding that children with the highest initial levels of blood pressure did not have the largest subsequent increase suggests that there is no "horse-racing" of blood pressure during childhood. There is some evidence that the relation between initial level and subsequent change in blood pressure is modified by age.

Altitude and blood pressure in children

People living at high altitude are generally observed to have lower blood pressure than those residing at sea level. To investigate whether low pO2 or low body weight accounts for this, blood pressure, weight, height and pulse rate were measured in 847 Peruvian children residing at 3500 m and compared to previously collected data in 3924 Dutch children living at sea level. In the two study populations the same protocol for measurement of blood pressure was used by observers who showed no systematic differences in average blood pressure readings during training sessions. Systolic as well as diastolic blood pressure was found to increase with age in both Peruvian and Dutch children. Systolic blood pressure by age was 5-10 mmHg lower in Peruvian boys and girls than in their Dutch counterparts. However, virtually no differences in systolic blood pressure, and to a lesser extent diastolic blood pressure, by body weight or height between Peruvian and Dutch subjects were found. These findings are in agreement with the hypothesis that differences in body weight, rather than in pO2, explain most of the observed differences in blood pressure between children of the same age living at different altitudes.

Blood pressure and haemodynamics in teenagers

It has been suggested that a hyperkinetic circulatory state, with high cardiac output, causes high blood pressure in childhood and, secondarily, in adulthood. We studied blood pressure and cardiac output in 319 subjects aged 15 to 19. Blood pressure was measured with an automated device; cardiac output was estimated by M-mode echocardiography and indexed by body surface area. The distribution of cardiac output was stratified using quartiles. Mean arterial pressure was virtually constant over these strata, with boys and girls showing essentially the same pattern. Linear regression of mean arterial pressure on cardiac output yielded a coefficient which was not significantly different from zero. A history of high blood pressure in the parents was positively associated with mean arterial pressure, but unrelated to cardiac output, in the offspring. This evidence does not support the hypothesis that the hyperkinetic circulatory state causes high blood pressure in childhood; rather, raised blood pressure in adolescents appears to relate to increased peripheral vascular resistance. Therefore, our findings lend support to the view that change in blood pressure over time is caused by a gradual increase in peripheral resistance beginning early in life.

Trends in the use of oral contraceptives among Dutch young women 1975-1981

Prompted by a recent report of a decrease in the use of oral contraceptive in the U.S.A., we investigated the trends by age and time of oral contraceptives use among Dutch young women, born between 1955 and 1970. They participated in a follow-study of risk-indicators for cardiovascular disease. A random sample of 596 subjects, initially aged 5-19, and selected from an open population, was invited for annual exams since 1975; 462 youngsters (226 girls) underwent at least three annual exams. They were asked each year whether they used oral contraceptives. Analysis of the trend by age showed an increase of the proportion of oral contraceptives users from less than 5% at an age of 15 to about 50% at 23 years of age. In the 1959-1962 birth cohort, the proportion of users was twice as large as that of the 1955-1968 cohort. The 1963-1966 cohort followed the pattern of the 1959-1962 birth-cohort. These findings indicate that there has been a strong increase in the use of oral contraceptives among Dutch women born after 1958. We found no evidence for a recent decrease in the use of oral contraceptives in the Netherlands among young women.

Haemodynamics, plasma noradrenaline and plasma renin in hypertensive and normotensive teenagers

1. Plasma noradrenaline, active and inactive plasma renin, cardiac index and total peripheral vascular resistance were studied in 41 subjects, initially aged 10-19 years, who were followed up for at least 2 years after a blood pressure reading of 140 and/or 90 mmHg or more (initial hypertensives) and in 41 normotensive control subjects selected from the same population and matched for age, sex and body-mass index. 2. The initial hypertensive subjects had a lower mean cardiac index (3.63 +/- SD 0.83 vs 4.00 +/- 0.89 litre min-1 m-2), a higher mean total peripheral resistance (26.8 +/- 5.7 vs 22.8 +/- 5.5 peripheral resistance (26.8 +/- 5.7 vs 22.8 +/- 5.5 units) and a higher mean plasma noradrenaline units) and a higher mean plasma noradrenaline concentration (336 +/- 146 vs 281 +/- 126 pg/ml) than the control subjects. 3. Mean plasma noradrenaline concentration was higher in initial hypertensive subjects with a high active renin concentration than in those with a normal renin concentration (442 +/- 70 vs 324 +/- 100 pg/ml). 4. A weight-adjusted standardized regression coefficient of 0.77 between active plasma renin concentration and left ventricular mass was found in normotensive control subjects. 5. These findings are at variance with the existence of a hyperkinetic phase in young hypertensive subjects and suggest that sympathetic overactivity may be related to early essential hypertension through increase of peripheral vascular resistance.

Increased blood pressure in schoolchildren related to high sodium levels in drinking water

The relationship between sodium in drinking water and blood pressure was examined in 348 schoolchildren aged 7.7 to 11.7 years. They were born and living in three areas with different levels of sodium in the public drinking water. Sodium content of the water was either long-term low, long-term high, or short-term high. The three communities are closely comparable according to demographic characteristics. The mean values of systolic and diastolic blood pressure were higher in the high sodium areas. After adjustment for dissimilarities in distributions of weight, height, pulse rate, age, family history of hypertension, and time of blood pressure measurement, these differences remained constant, ranging from 1.8 to 4.0 mm Hg. Girls and boys showed essentially the same differences. Mean 24-hour sodium excretion was somewhat higher in the long-term low area; no differences were found in sodium-creatinine ratio. The regression coefficients between sodium excretion and blood pressure were not significant. The findings from this retrospective follow-up study support the hypothesis that sodium intake influences blood pressure. The association seems to be of a relatively short-term nature, as no differences in blood pressure levels were found between the long-term and short-term high areas.

Raised blood pressure and plasma noradrenaline concentrations in teenagers and young adults selected from an open population

Plasma noradrenaline (PNA) concentrations were measured in 38 subjects aged 13-23, who were followed up for two to four years after an initial blood-pressure (BP) reading of 140/90 mm Hg or over was obtained, and in 39 age-matched controls from the same open population. Subjects who were hypertensive when the PNA concentration was measured had a significantly higher concentration (351 +/- SE 26 pg/ml) compared with their controls (248 +/- 29 pg/ml). Furthermore, in those subjects in whom the mean arterial pressure decreased by under 5% during the follow-up period the mean concentration was 363 +/- 27 pg/ml, compared with 271 +/- 29 pg/ml in their controls. PNA concentrations and systolic BP were positively correlated. A positive association between PNA concentrations and age was observed in the controls but not the subjects with hypertension, owing to the higher concentrations in younger hypertensive subjects.

Periodontal disease and blood citrate levels in patients with trisomy 21

Elevated blood-citrate levels, poor oral hygiene, and macroglossia were associated with early, severe periodontitis in mongoloids.