Circadian Blood Pressure Rhythm in Primary and Secondary Hypertension

Circadian blood pressure variability was recorded in patients with primary hypertension and with different forms of secondary hypertension using ambulatory 24-h blood pressure measurement. A group of 20 patients with different forms of secondary hypertension was compared with a matched group of patients with primary hypertension. Although the mean 24-h blood pressure was not different between the two groups, the patients with secondary hypertension had significantly higher systolic blood pressure during sleep and higher systolic and diastolic blood pressure in the early morning, compared with the primary hypertension group. This nocturnal blood pressure fall was then investigated in various groups of patients with different forms of secondary hypertension and compared with normotensives and patients with primary hypertension. Patients with mild primary hypertension (n = 152) and with severe primary hypertension (n = 30) had the same blood pressure fall (14–16 mm Hg systolic and diastolic) during the night (23:OO–05:OO h) as normotensives (n = 20). However, in patients with renoparenchymal hypertension (n = 29), renovascular hypertension (n = 20), hyperaldosteronism (n = 6), and hyperthyroidism (n = 14), the nocturnal blood pressure fall was significantly (p < 0.01) reduced. One patient with coarctation ofthe aorta and nine patients with primary hyperparathyroidism and elevated blood pressure had a normal circadian blood pressure profile with a normal nocturnal blood pressure fall. The heart rate decrease during the night was equal in all patient groups. Ambulatory blood pressure measurement allows blood pressure recording under everyday conditions, including nighttime. In primary hypertension the blood pressure variability exhibits the same circadian variation as in normotension, showing a marked nocturnal fall. However, in different forms of secondary hypertension, blood pressure shows a blunted circadian curve. This could have important diagnostic and therapeutic implications.     

Circadian blood pressure rhythm in primary and secondary hypertension.

Circadian blood pressure variability was recorded in patients with primary hypertension and with different forms of secondary hypertension using ambulatory 24-h blood pressure measurement. A group of 20 patients with different forms of secondary hypertension was compared with a matched group of patients with primary hypertension. Although the mean 24-h blood pressure was not different between the two groups, the patients with secondary hypertension had significantly higher systolic blood pressure during sleep and higher systolic and diastolic blood pressure in the early morning, compared with the primary hypertension group. This nocturnal blood pressure fall was then investigated in various groups of patients with different forms of secondary hypertension and compared with normotensives and patients with primary hypertension. Patients with mild primary hypertension (n = 152) and with severe primary hypertension (n = 30) had the same blood pressure fall (14-16 mm Hg systolic and diastolic) during the night (23:00-05:00 h) as normotensives (n = 20). However, in patients with renoparenchymal hypertension (n = 29), renovascular hypertensions (n = 20), hyperaldosteronism (n = 6), and hyperthyroidism (n = 14), the nocturnal blood pressure fall was significantly (p less than 0.01) reduced. One patient with coarctation of the aorta and nine patients with primary hyperparathyroidism and elevated blood pressure had a normal circadian blood pressure profile with a normal nocturnal blood pressure fall. The heart rate decrease during the night was equal in all patient groups. Ambulatory blood pressure measurement allows blood pressure recording under everyday conditions, including nighttime. In primary hypertension the blood pressure variability exhibits the same circadian variation as in normotension, showing a marked nocturnal fall.(ABSTRACT TRUNCATED AT 250 WORDS)     

Beta-adrenoreceptor blockade in the conscious rabbit: effects on plasma renin activity and blood pressure.

The administration of a single dose of dl-propranolol, 1 mg/kg i.v., in the conscious unstimulated rabbit produced effective beta-adrenoreceptor blockade (inhibition of isoprenaline tachycardia) for 150 min. During this period there was a positive correlation between plasma concentrations of propranolol and the degree of beta-blockade observed. In a further group of animals treated with propranolol, plasma renin activity (PRA) fell to 50% of control (P < 0.001) within 60 min, the rate of change of PRA also correlating with plasma propranolol levels. Similarly, there were reductions in mean blood pressure (P < 0.025) and heart rate (P < 0.025). Statistical relationships between the fall in blood pressure and either pre-treatment PRA or the change in PRA were consistent with the hypothesis that the hypotensive effect of propranolol was dependent upon its suppression of renin release. However, an alternative possibility that the fall in blood pressure was due to an acute reduction in cardiac output could not be excluded.     

Diagnostic dilemma of cardiac syncope in pediatric patients

Aims

Syncope is defined as temporary loss of consciousness and postural tone resulting from an abrupt transient decrease in cerebral blood flow. The present work aimed at determining how diagnostic tests are used in the evaluation of pediatric syncope at a tertiary pediatric referral center and to report on the utility and the yield of these tests.

Settings and Design

Retrospective study conducted at a tertiary referral arrhythmolology service

Methods and Material

The clinical charts of 234 pediatric patients presenting with a primary complaint of syncope with an average age of 7.48 ± 3.82(3.5-16) years were reviewed by the investigators.

Statistical analysis used

Statistical Package of social science (SPSS) version 9,0 was used for analysis of data.

Results

The commonest trigger for syncope in the study population was early following exercise (n=65) and the commonest prodrome was palpitation, noted in 25 patients. A murmur was present in 19 of our patients (8.3%) while 10.7% (n=25) had abnormal ECGs. Of the 106 echocardiograms done, 14 (13.2%) were abnormal. Only two of them were missed by ECG. All patients were offered ambulatory 24 hour ECG. One patient with sick sinus syndrome was diagnosed only with Holter.

Conclusions

Clues to the presence of cardiac syncope may include acute onset of syncope, frequent episodes, low difference between blood pressure readings in supine and erect positions (after standing for 2 minutes) and most importantly an abnormal 12 lead ECG. Transthoracic echo and Holter monitoring have low yield in pediatric syncope.     

Why hypertensive patients vary in their response to oral debrisoquine.

The relation between dose, systemic availability, and response to oral debrisoquine was studied in 13 hypertensive patients receiving no other treatment. In 11 who received the same daily dose (40 mg) the fall in mean standing systolic blood pressure varied between 0-3 and 44-4 mm Hg. There was a ninefold difference in the daily urinary excretion and pre-dose plasma concentration of unchanged drug but an inverse correlation between daily urinary excretion of debrisoquine and its 4-hydroxy metabolite (r= -0-86), suggesting that a low recovery of debrisoquine occurs because of extensive metabolism. There was a significant correlation between the fall in standing systolic blood pressure and the mean daily urinary excretion (r= +0-82) and pre-dose plasma concentration (r= +0-82) of unchanged debrisoquine. In contrast, there was a significant inverse correlation between the urinary recovery of the metabolite and the fall in blood pressure (r= -0-82). The availability of debrisoquine is the major determinant of response to this drug. In the absence of side effects a poor response may be an indication to increase the daily dose rather than add another hypotensive agent.     

Plasma leptin levels strongly correlate with plasma renin activity in patients with essential hypertension.

Previous studies demonstrated elevated plasma leptin and angiotensinogen (PRA) levels in essential hypertension. However, a few studies investigated the relationship between leptin and angiotensinogen levels in both lean and overweight/ obese hypertensives. The aim of the present study was therefore to examine the relationship between blood pressure, leptin and plasma renin activity in normotensives and in both lean and overweight/obese patients with essential hypertension. Two groups of subjects who were carefully matched for age, gender, waist:hip ratio and body mass index (BMI) were studied: 28 normotensives (NT) (age: 40.1+/-9.1 years old, BMI: 28.1+/-3.6 kg/m2, male/female: 18/10) and 33 newly diagnosed mild to moderate essential hypertensives (EHT) (age: 38.9+/-10 years old, BMI: 27.9+/-4.8 kg/m2, male/female: 22/11). No significant differences in age, gender, waist:hip ratio, fasting blood glucose and BMI were detected between EHT and NT groups. However, systolic and diastolic pressures, mean arterial blood pressures, plasma leptin levels and PRA were significantly higher in EHT group than in NT group (P = 0.001). Plasma leptin levels were strongly correlated with BMI in EHT (r=0.67, P = 0.001) and NT groups (r=0.44, P = 0.001). Plasma leptin levels were correlated with plasma PRA levels in both EHT and NT groups (r = 0.66 and r = 0.44; both P < 0.05, respectively). There was no correlation between leptin or PRA and systolic, diastolic pressures, or mean arterial blood pressures. Furthermore, the patients were divided as lean (n=16) and overweight/obese (n = 17) and compared with BMI-matched controls. In both subgroups, plasma leptin and PRA levels were also higher than those of controls. Our results showed that elevated plasma leptin and PRA are associated with hypertension in both lean and overweight/obese hypertensives. Moreover, plasma leptin was significantly correlated with plasma angiotensinogen levels. These findings suggest that adipose mass is an important determinant of blood pressure, although the mechanism is not clear.     

Initial blood pressure fall on stand up and exercise explained by changes in total peripheral resistance

To elucidate the underlying mechanisms of the initial fall in blood pressure on standing upright from the supine position, we measured the beat-to-beat changes in intra-arterial pressure in eight healthy male subjects in response to standing. Changes in stroke volume, cardiac output, and total peripheral resistance were computed from the pressure waveform using a pulse contour method. To determine possible mechanisms for the changes observed on standing, similar measures were made on passive tilting and a brief (3-s) bout of cycle exercise. Standing elicited a transient 25% (23-mmHg) fall in mean blood pressure as a result of a 36% fall in total peripheral resistance. Head-up tilt elicited a gradual change in haemodynamic parameters, which reached plateau levels in 20-30 s. Cycling elicited a transient 17% (18-mmHg) fall in blood pressure and a 41% fall in total peripheral resistance. In addition, we measured right atrial and esophageal pressures in two subjects on standing and cycling and found a 10- to 15-mmHg rise in right atrial pressure without a corresponding change in esophageal pressure. This points to the cardiopulmonary reflex as the primary effector of peripheral vasodilation, but we cannot exclude the possibility that 1) local metabolic vasodilation and 2) central command-mediated cholinergic vasodilation contributed to the fall in vascular resistance.     

Role of catecholamines in hypotensive response to dieting.

The effect of dieting on blood pressure and catecholamine metabolism was assessed in 11 normotensive obese women by providing first a weight-maintenance regimen high in carbohydrate and then a low-energy diet. All dietary constituents other than carbohydrate were maintained constant throughout the 18-day study. The low-carbohydrate diet led within 48 hours to a 41% fall in the urinary output of 4-hydroxy-3-methoxy mandelate and a significant fall in systolic and diastolic blood pressure. Plasma noradrenaline concentrations also fell and the hypotensive effect of the diet continued despite a maintained total body sodium. Thus the fall in blood pressure appeared to be mediated by changes in catecholamine metabolism independent of sodium intake. This may explain both the usefulness of weight reduction in hypertensive patients and the fainting that occurs in some normotensive obese subjects taking slimming regimens low in carbohydrate.     

Blood pressure response to standing in the diagnosis of autonomic neuropathy: the EURODIAB IDDM Complications Study

Autonomic neuropathy is associated with poor prognosis. Cardiovascular reflexes are essential for the diagnosis of autonomic nerve dysfunction. Blood pressure response to standing is the most simple test for the evaluation of sympathetic integrity, however it is still discussed which diagnostic criteria of abnormal response should be considered as optimal. The EURODIAB IDDM Complications Study involved the examination of randomly selected Type 1 diabetic patients from 31 centres in 16 European counties. Data from 3007 patients were available for the present evaluation. Two tests of autonomic function (response of heart rate /R-R ratio/ and blood pressure from lying to standing) just as the frequency of feeling faint on standing up were assessed. R-R ratio was abnormal in 24% of patients. According to different diagnostic criteria of abnormal BP response to standing (>30 mmHg, >20 mmHg, and >10 mmHg fall in systolic BP), the frequency of abnormal results was 5.9%, 18% and 32%, respectively (p < 0.001). The frequency of feeling faint on standing was 18%, thus, it was identical with the prevalence of abnormal blood pressure response to standing when >20 mmHg fall in systolic blood pressure was considered as abnormal. Feeling faint on standing correlated significantly with both autonomic test results (p < 0.001). A fall >20 mmHg in systolic blood pressure after standing up seems to be the most reliable criterion for the assessment of orthostatic hypotension in the diagnosis of autonomic neuropathy in patients with Type 1 diabetes mellitus.     

Effect of somatostatin on plasma renin activity and blood pressure in patients with essential hypertension

The effects of somatostatin on plasma renin activity (PRA) and blood pressure were evaluated in patients with essential hypertension (EH) and in normotensive subjects. All subjects examined were hospitalized and placed on a diet containing 7-8 g/day sodium chloride and received an intravenous infusion of somatostatin (500 microgram/20 ml of saline, for 60 min) in the basal condition. During somatostatin infusion, the mean blood pressure (MBP) remained unaffected in all patients with EH and the normotensive subjects, while the PRA decreased slightly in the EH group. When the patients with EH were classified according to their renin levels (low, normal and high), parallel significant decreases in MBP and PRA were found only in the high renin group during the somatostatin infusion. No significant change in MBP and PRA was observed in the other groups including the normotensive subjects. To assess the activity of synthetic somatostatin, the plasma levels of growth hormone (GH) and cyclic AMP were measured. These levels were lowered significantly during the infusion and the GH levels showed a rebound 15 min after cessation of the infusion. The cyclic AMP returned to the basal levels, but no rebound was observed. The above data indicate that the fall in blood pressure in the high renin group in the basal condition was probably due in part to reduced renin release by somatostatin, and the maintenance of high blood pressure especially in high renin EH.     

电刺激延髓最后区对血浆肾素活性及肾交感神经...

68 urethan-anesthetized rabbits were prepared for registration of changes of respiration, arterial blood pressure (BP), heart rate (HR) and renal sympathetic nerve activity (RSNA) due to stimulation of area postrema (AP) by rectangular pulse trains each lasting for 4 s for every 30 s. During 40 min of such a stimulation paradigm the venous blood samples were collected for radioimmunoassay of plasma renin activity (PRA) (both pre- and post-stimulation), RSNA registered and processed by a computer. Animals were divided into three groups: (1) with AP stimulation only (n = 47); (2) AP stimulation after bilateral renal denervation (n = 13); (3) AP stimulation after propranolol injection (n = 8). In Group I, a 91% increase in PRA, an augmentation of RSNA, a rise of BP and a decrease of HR were observed, while respiration did not show obvious change. In Group II, hemodynamic and RSNA response was similar to that in Group I, but PRA was not changed significantly. In Group III, the effects on BP, HR, respiration and RSNA showed no remarkable changes compared with Group I, but significant inhibition of the response of PRA [from 0.65 +/- 0.07 ng/(ml.h-1) to 0.72 +/- 0.10 ng/(ml.h-1), P > 0.05] was observed. The results mentioned above suggested that electrical stimulation of AP may induce an increase in renin release and renal sympathetic nerve activity and hemodynamic changes in rabbits.     

High altitude and blood pressure in children

We aimed to evaluate the blood pressure of children who had similar demographic characteristics but lived at different altitudes. Blood pressure of the children attending primary schools in Izmir (sea level: n = 425) and Van (altitude: 1725 m, n = 291) were measured by mercurial sphygmomanometer for this study. They were similar with respect to age, sex, weight, height, and BMI. Mean age of the children was 10.51 +/- 0.87 years (range: 9 to 12 years), and 358 (50 percent) of them were female. Mean systolic blood pressure was significantly higher in the children living in Van than in the children living in Izmir (104.72 +/- 11.2 vs. 97.96 +/- 25.5 mmHg, respectively, p < .001). Similarly mean diastolic blood pressure was significantly higher in the children living in Van than in the children living in Izmir (63.98 +/- 9.3 vs. 59.91 +/- 10.0 mmHg, respectively, p < .001). When blood pressure was evaluated with regard to height percentile, the number of children with a blood pressure over 90 percentile were 19 (4.5 percent) and 48 (16.5 percent) for systolic blood pressure, and 25 (5.9 percent) and 37 (12.7 percent) for diastolic blood pressure among the children living in Izmir and Van, respectively (p < .001). Systolic and diastolic blood pressures were found to increase in parallel to the increase in body mass index in children living in Van (r = 0.358, p < .001 and r = 0.235, p < .001, respectively). However, blood pressures were not correlated to body mass index in children living in Izmir. A difference of 1700 m in altitude was associated with higher systolic and diastolic blood pressure levels in children with similar demographic characteristics, and at this altitude, body mass index and blood pressure showed a positive correlation.     

Effects of various doses of captopril on plasma aldosterone concentrations in patients with essential hypertension

Various doses (5 mg, 12.5 mg and 25 mg) of angiotensin I converting enzyme inhibitor (SQ 14,255, captopril) were administered to 8 patients with essential hypertension on a three-crossover study design, and the time course of mean blood pressure (MBP), plasma renin activity (PRA), plasma angiotensin converting enzyme activity (ACE-A), plasma cortisol (PC) and plasma aldosterone (PA) were determined following administration of the drug. MBP fell in a dose dependent manner, and PRA showed a minor but significant increases in cases receiving 5 and 12.5 mg of the drug. A large and significant increase in PRA was observed following 25 mg of captopril. ACE-A was also reduced in a dose dependent manner. There was no difference between changes in PC at any of the three dose levels. The serum potassium concentration was determined before and 3 hr after 25 mg of captopril treatment and no significant change was observed. In spite of the dose dependent and theoretical changes in the above parameters, lowered responses of PA to each dose of the drug were shown in reverse order against an increasing dose. That is to say, the grade of fall in PA following 25 of captopril was smaller than that following the other doses of the drug, and 5 mg induced a greater decrease in PA than 12.5 mg. Based on these findings, the relatively high dose of captopril in the present study was apparently more effective in increasing some factors which suppressed reduction of PA by a fall in angiotensin II than a low dose of the drug.     

Response of adrenal steroids to angiotensin II in essential hypertension

The effect of angiotensin II (A II) on the plasma corticosteroid concentration and blood pressure was investigated in five normotensive subjects and 24 patients with essential hypertension (EH). Infusion of A II in normal subjects caused a significant increase in plasma aldosterone and significant decreases in plasma renin activity (PRA), plasma cortisol and dehydroepiandrosterone-sulfate (DHEA-S), while plasma levels of deoxycorticosterone (DOC) and ACTH remained unchanged. In patients with EH, A II infusion caused a significant decrease in PRA and a significant increase in plasma aldosterone. The percent increase in plasma aldosterone was greatest in patients with high PRA when compared to the low and normal PRA groups. The mean plasma levels of cortisol, DOC and DHEA-S after A II infusion were significantly increased in patients with high PRA but no significant changes were observed in patients with low or normal PRA. The mean blood pressure in patients with low PRA was sharply increased during the infusion when compared to the other two groups and did not return to the baseline level after cessation of the infusion. Hepatic blood flow as estimated by the disappearance rate constant of indocyanine green was significantly lower in patients with low PRA than in patients with high PRA. The above results suggest that different responses to A II infusion in steroid biosynthesis may exist between normal subjects and patients with EH. These observed phenomena may be due to biochemical (serum sodium) or functional (plasma A II level) differences in the A II receptor site or to the difference in the metabolic clearance of A II in patients with EH.     

Plasma active renin concentration in children

In normal children aged one month to 16 years, the plasma active renin concentration (PARC) was measured with a renin immunoradiometricassay (IRMA) kit, and was compared with plasma renin activity (PRA). The IRMA for renin was found to be independent of the amount of renin substrate and not affected by the dilution of plasma samples, and was therefore proved to be a simple and reliable method. PRA measured in non-diluted plasma samples correlated well with PARC. In the age-related change, PARC in infants was significantly higher than that in older children. In infants, PARC was markedly higher in the crying state than that in the non-crying state. In normal children aged 7 to 11 years, PARC was significantly increased in the upright position compared to the supine position. These findings suggest that a hyperresponse of PARC to acute stress during blood sampling may cause an increase in active renin secretion in infants, and that stimulation by short-term standing may accelerate the activation of inactive renin or the release of active renin.     

Middle cerebral artery blood velocity during a valsalva maneuver in the standing position.

Occasionally, lifting of a heavy weight leads to dizziness and even to fainting, suggesting that, especially in the standing position, expiratory straining compromises cerebral perfusion. In 10 subjects, the middle cerebral artery mean blood velocity (V(mean)) was evaluated during a Valsalva maneuver (mouth pressure 40 mmHg for 15 s) both in the supine and in the standing position. During standing, cardiac output decreased by 16 +/- 4 (SE) % (P < 0.05), and at the level of the brain mean arterial pressure (MAP) decreased from 89 +/- 2 to 78 +/- 3 mmHg (P < 0.05), as did V(mean) from 73 +/- 4 to 62 +/- 5 cm/s (P < 0.05). In both postures, the Valsalva maneuver increased central venous pressure by approximately 40 mmHg with a nadir in MAP and cardiac output that was most pronounced during standing (MAP: 65 +/- 6 vs. 87 +/- 3 mmHg; cardiac output: 37 +/- 3 vs. 57 +/- 4% of the resting value; P < 0.05). Also, V(mean) was lowest during the standing Valsalva maneuver (39 +/- 5 vs. 47 +/- 4 cm/s; P < 0.05). In healthy individuals, orthostasis induces an approximately 15% reduction in middle cerebral artery V(mean) that is exaggerated by a Valsalva maneuver performed with 40-mmHg mouth pressure to approximately 50% of supine rest.     

儿童直立调节试验对不明原因晕厥的诊断价值

目的:探讨直立倾斜试验对儿童不明原因晕厥的诊断价值,为临床诊断提供科学依据。方法:对208例不明原因晕厥的儿童给予进行直立倾料试验检查,持续进行心电监护监测,记录其血压、心率变化,分析试验结果。结果:145例(69.71%)出现阳性的血管迷走神经反应,73例(50.34%)为血管抑制型反应;19例(13.10%)呈心脏抑制型反应;53例(36.55%)为混合型反应型,并且诱发因子多为持久站立。结论:不明原因晕厥患者在直立倾斜试验中以血管迷走反应为主,持久站立是血管迷走神经性晕厥的主要诱因。     

Plasma levels of renin, angiotensin II, and 6-ketoprostaglandin F1 alpha in endurance athletes

Twelve male runners and 12 matched nonathletes performed a prolonged uninterrupted graded exercise test on the bicycle ergometer up to exhaustion to study blood pressure and plasma levels of renin (PRA), vasoconstrictor angiotensin II (ANG II), and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), a metabolite of the vasodilator prostacyclin. In the athletes work load was increased by 30 W/4 min, and in the control subjects the increments of work load were adjusted to their lower exercise capacity to equalize total exercise duration. Blood was drawn, and blood pressure and O2 uptake (VO2) were measured at rest and at the fourth, eighth, and last steps of exercise. Peak VO2 averaged 60 +/- 1.6 ml . min-1 . kg-1 in the runners and 46.8 +/- 1.5 in the nonathletes. To evaluate differences between athletes and controls, PRA, ANG II, and 6-keto-PGF1 alpha were first adjusted for significant confounding factors, such as age, weight, hematocrit, 24-h urinary sodium excretion, and O2 uptake. PRA was significantly lower in the athletes (F = 11.2; P less than 0.01); ANG II was not different at rest, but its rise with exercise was less steep in the runners (F = 8.2; P less than 0.01), whereas 6-keto-PGF1 alpha was not different between the groups (F = 1.3; NS). Despite the differences in PRA and ANG II, however, blood pressure was similar in athletes and nonathletes (F = 0.0; NS).     

Arterial hypertension caused by low renin: comparison of the calcium antagonist nifedipine and the ACE-inhibitor enalapril as to antihypertensive efficacy

The aim of this study was to compare the clinical effects of calcium-entry blocker Nifedipine and ACE-inhibitor Enalapril in hypertensive patients with glucose intolerance that have lower plasma renin activity. A blood sample for basal PRA was obtained from 21 subjects; then, 11 patients received Nifedipine (20 mg. b.i.d.) and 10 Enalapril (20 mg. q.d.). The extent of blood pressure fall after 12 weeks of treatment was inversely related to basal PRA levels in Nifedipine treated group only; however, the hypotensive effect of both drugs was comparable.     

Investigation of subclinical signs of autonomic neuropathy in the early stage of childhood diabetes

It has been suggested that subclinical signs of neuropathy appear earlier than microvascular complications of diabetes. To evaluate the occurrence of autonomic nervous system dysfunction in the early stage of childhood diabetes, subclinical signs of autonomic neuropathy (resting heart rate, hyperventilatory arrhythmia, standing/lying heart rate ratio, orthostatic decrease in blood pressure, and increase in blood pressure during sustained handgrip) were investigated in 54 children with type 1 diabetes divided into three groups: 14 recent-onset diabetics (3 weeks after the diagnosis), 20 diabetics in the remission phase, and 20 patients after the remission phase. 30 healthy age-matched children were used as control group. The mean resting heart rates of the diabetic groups in the remission phase and after the remission phase were significantly higher than those in the healthy control group (81.7 +/- 5/min and 88.5 +/- 6/min vs. 72.2 +/- 8/min; p less than 0.01). The hyperventilatory arrhythmia in the group of diabetic children after the remission phase in comparison with the control group was significantly decreased (29.1 +/- 4/min vs. 22.7 +/- 3/min; p less than 0.01). In a few cases of the recent-onset diabetic group, the increase in resting heart rate, the decrease in hyperventilatory arrhythmia, and the standing/lying heart rate ratio proved to be significant. In the remission phase, the same parameters showed abnormal values in one third to one fifth of the children.(ABSTRACT TRUNCATED AT 250 WORDS)