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Biomedical subjects

H Rüddel

Publications and source records attributed to H Rüddel.

At least 19 recordsLinked to original sources
PubMed1999

Early autonomic dysfunction in patients with diabetes mellitus assessed by spectral analysis of heart rate and blood pressure variability.

Patients with diabetes mellitus (DM) often have alterations of the autonomic nervous system (ANS), even early in their disease course. Previous research has not evaluated whether these changes may have consequences on adaptation mechanisms in DM, e.g. to mental stress. We therefore evaluated whether patients with DM who already had early alterations of the ANS reacted with an abnormal regulatory pattern to mental stress. We used the spectral analysis technique, known to be valuable and reliable in the investigation of disturbances of the ANS. We investigated 34 patients with DM without clinical evidence of ANS dysfunction (e.g. orthostatic hypotension) and 44 normal control subjects (NC group). No patients on medication known to alter ANS responses were accepted. The investigation consisted of a resting state evaluation and a mental stress task (BonnDet). In basal values, only the 21 patients with type 2 DM were different in respect to body mass index and systolic blood pressure. In the study parameters we found significantly lower values in resting and mental stress spectral power of mid-frequency band (known to represent predominantly sympathetic influences) and of high-frequency and respiration bands (known to represent parasympathetic influences) in patients with DM (types 1 and 2) compared with NC group (5.3 +/- 1.2 ms2 vs. 6.1 +/- 1.3 ms2, and 5.5 +/- 1.6 ms2 vs. 6.2 +/- 1.5 ms2, and 4.6 +/- 1.7 ms2 vs. 6.2 +/- 1.5 ms2, for resting values respectively; 4.7 +/- 1.4 ms2 vs. 5.9 +/- 1.2 ms2, and 4.6 +/- 1.9 ms2 vs. 5.6 +/- 1.7 ms2, and 3.7 +/- 2.1 ms2 vs. 5.6 +/- 1.7 ms2, for stress values respectively; M/F ratio 6/26 vs. 30/14). These differences remained significant even when controlled for age, sex, and body weight. However, patients with DM type 2 (and significantly higher body weight) showed only significant values in mental stress modulus values. There were no specific group effects in the patients with DM in adaptation mechanisms to mental stress compared with the NC group. These findings demonstrate that power spectral examinations at rest are sufficiently reliable to diagnose early alterations in ANS in patients with DM. The spectral analysis technique is sensitive and reliable in investigation of ANS in patients with DM without clinically symptomatic autonomic dysfunction.

Adult↗
PubMed1998

[Quality assurance in inpatient psychosomatic treatment and rehabilitation].

In addition to the requirements of quality management imposed by legislative and in consideration of research projects on the evaluation of psychotherapy the German pension funds introduced a systematic program for quality control in 1994. By the end of this year all the German rehabilitation centers will regularly have to provide information concerning the structure and concepts of the hospital and details of the rehabilitation programs. All therapeutic interventions are listed for every patient. In a subsample of patients detailed information regarding diagnosis and outcome (goal attainment) is required in addition to the final report. A subsample of the final reports is peer-reviewed. Patient's satisfaction and estimation of outcome variables are regularly assessed 3 months after discharge. Within and between institutions quality circles meet regularly. Advantages and limits of these programs are discussed and additional approaches towards total quality management in Bad Kreuznach are described.

Germany↗
PubMed1995

Predictors for hypertensive nephropathy: results of a 6-year follow-up study in essential hypertension.

OBJECTIVE AND DESIGN: To identify predictors for the development of early hypertensive nephropathy, 88 previously untreated patients with mild-to-moderate essential hypertension (World Health Organization stage I or II) were re-examined after 6 years of follow-up. According to previous results, protein excretion, urinary excretion of N-acetyl-beta-glucosaminidase (NAG), serum NAG concentration and glomerular filtration rate (creatinine clearance) may predict the change in renal function. RESULTS: Serum creatinine level increased significantly, but none of the patients developed serum creatinine of > 1.3 mg/dl. An elevated protein excretion between 200 and 500 mg/day at baseline (microproteinuria), urinary NAG excretion, serum NAG concentration and blood pressure control during treatment were not related to serum creatinine level at follow-up or change in serum creatinine level throughout the 6 years of follow-up. In contrast, a high creatinine clearance at baseline was related to a marked rise in serum creatinine level after 6 years. The patients with a clear-cut increase in serum creatinine level of > 0.2 mg/dl (n = 23) were characterized by a significantly higher pretreatment blood pressure at the worksite and a significantly greater initial creatinine clearance than the patients with no significant change in serum creatinine level. In the two groups age, blood pressure level during therapy, and the intensity and duration of blood pressure control were not different. CONCLUSION: In patients with uncomplicated essential hypertension, microproteinuria, NAG parameters and treatment blood pressure level did not predict the change in serum creatinine level in the first 6 years of follow-up. A high creatinine clearance (suggesting glomerular hyperfiltration) emerged as a clinical diagnostic marker of early hypertensive nephropathy.

Adult↗
PubMed1994

Reduced parasympathetic cardiac control in patients with hypertension at rest and under mental stress.

The neurogenic component in the pathogenesis of essential hypertension has predominantly been analyzed with regard to the sympathetic part of the autonomous nervous system; the parasympathetic branch has largely been neglected. We investigated whether 54 normotensive (mean causal blood pressure [cBP]: 125 +/- 6/82 +/- 4 mm Hg), 41 borderline hypertensive (cBP: 134 +/- 8/90 +/- 5 mm Hg), and 34 hypertensive men (cBP: 152 +/- 13/101 +/- 5 mm Hg) without secondary target organ damage differed in parasympathetic cardiac control. Parasympathetic cardiac control was assessed via the amount of fast fluctuations (0.15 to 0.40 Hz; vagus band) and by the amount of respiratory-linked fluctuations (mean respiratory frequency +/- 0.03 Hz) in the power spectra of continuously registered interbeat intervals under the following conditions: mean of three rest phases with 10, 5, and 5 minutes' duration (REST); mean of two modes of a reaction time task with 10 and 5 minutes' duration (RTT); mean of 5 minutes' mental arithmetic plus noise (MA). Analysis of variance (ANOVA) shows that spectral energy in the so-called vagus band reveals the most prominent differences between blood pressure groups under all conditions: REST = normotensive, 2.70 +/- 0.31; borderline hypertensive, 2.55 +/- 0.33; and hypertensive, 2.43 +/- 0.43 (F[2.126] = 6.19; p < 0.01). RTT = normotensive, 2.41 +/- 0.35; borderline hypertensive, 2.19 +/- 0.33; and hypertensive, 2.17 +/- 0.46 (F[2.126] = 6.04; p < 0.01); MA = normotensive, 2.69 +/- 0.34; borderline hypertensive, 2.52 +/- 0.33; and hypertensive, 2.38 +/- 0.46 (F[2.126] = 7.04; p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Obesity as a determinant for response to antihypertensive treatment.

OBJECTIVE: To test the hypothesis that beta blockers lower blood pressure more effectively than calcium entry blockers in obese hypertensive patients and that calcium entry blockers are more effective in lean patients. DESIGN: Double blind, randomised controlled trial of treatment over six weeks. SETTING: Tertiary referral centre. SUBJECTS: 42 white men with uncomplicated mild to moderate essential hypertension (World Health Organisation stage I or II); 36 completed the study. INTERVENTION: Patients were randomised to metoprolol 50-100 mg twice daily or isradipine 2.5-5.0 mg twice daily for six weeks after a two week run in phase. MAIN OUTCOME MEASURE: Blood pressure after six weeks of treatment. RESULTS: When stratified according to treatment and presence of obesity (body mass index < or = 27 kg/m2), the mean (SD) fall in blood pressure in the beta blocker group was 24 (13)/18 (10) mm Hg in obese patients and 18 (19)/12 (13) mm Hg in lean patients. In the calcium entry blocker group, the fall in blood pressure was 21 (15)/17 (6) mm Hg in lean patients and 18 (11)/8 (10) mm Hg in obese patients. After taking age and blood pressure before treatment into account there was a significant interaction between obesity and drug therapy (p = 0.019) with a better diastolic blood pressure response to calcium entry blockers in lean patients and to beta blockers in obese hypertensive patients. CONCLUSION: Obesity affects the efficacy of metoprolol and isradipine in reducing blood pressure.

Blood Pressure↗
PubMed1993

Renal hemodynamics and cardiovascular reactivity in the prehypertensive stage.

To examine whether sympathetic nervous activation has an impact on renal circulation in subjects at risk for high blood pressure, we assessed renal hemodynamics and cardiovascular response to mental stress in 40 healthy young white males, 12 normotensive subjects without and 14 with familial hypertension, and 14 with borderline hypertension. The response of systolic and diastolic blood pressure to mental stress was assessed while each patient performed a mental arithmetic task; this was taken as the parameter for the activation of the sympathetic nervous system. Renal plasma flow was measured by para-aminohippuric acid clearance under steady-state conditions. In parallel, glomerular filtration rate as a parameter for functional impairment of the kidneys was determined by creatinine clearance, and filtration fraction was also calculated. Patients with borderline hypertension were characterized by a reduced renal blood flow and increased filtration fraction in comparison with both normotensive groups. The increase in systolic blood pressure during mental stress was more pronounced in borderline hypertensives. We observed no significant difference in renal hemodynamics and cardiovascular response to mental stress between normotensives with and without a family history of hypertension. In the total population, cardiovascular response to mental stress was correlated with renal hemodynamics: The greater the increase in systolic blood pressure during mental stress, the lower was the renal plasma flow and the greater the filtration fraction. Thus, renal plasma flow was found to be already reduced and filtration fraction increased before sustained hypertension developed. Because this pattern in renal hemodynamics was related to cardiovascular response to mental stress, our data suggest that sympathetic activation already appeared to affect renal hemodynamics at the onset of essential hypertension.

Adult↗
PubMed1992

Impact of antihypertensive therapy with isradipine and metoprolol on early markers of hypertensive nephropathy.

In a double-blind, randomized trial with 26 male white patients with essential hypertension in World Health Organization Stages I and II, we examined the impact of calcium entry blockade (5 to 10 mg/day isradipine, N = 14) and beta-blockade (100 to 200 mg/day metoprolol, N = 12) on early markers of hypertensive nephropathy before and after 7 weeks' treatment. Excretion of total protein, albumin, alpha 1-microglobuline, and N-acetyl-beta-glucosaminidase (NAG) were measured in the 24-h urine by radial immunodiffusion and fluorimetric method, respectively. Before therapy, 8 of 26 patients had microproteinuria (31%), six had microalbuminuria (22%), six had elevated urinary NAG activity (22%), and three had elevated alpha 1-microglobulin excretion (11%). In these subjects anti-hypertensive therapy led to a fall in proteinuria (296 +/- 56 v 127 +/- 116 mg/day, P less than .01), albuminuria (44 +/- 24 v 25 +/- 12 mg/day, P less than .05), and NAG excretion (45 +/- 22 v 28 +/- 5, P less than .05). The higher the pretreatment value, the greater the fall was in proteinuria (r = +0.55, P less than .01), albuminuria (r = 0.80, P less than .001), and NAG excretion (r = 0.60, P less than .01). We did not observe any significant difference in clinical characteristics, blood pressure, or urinary excretion of protein, albumin, or NAG between the two treatment groups, either before or after therapy. Thus, antihypertensive therapy reduced excretion of total protein, albumin, and NAG activity in hypertensive patients with elevated pretreatment values, potentially indicating reversal of early hypertensive nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMed1992

Impact of angiotensin converting enzyme inhibition on the haemodynamic profile during laboratory stress tests.

To determine the haemodynamic profile of angiotensin converting enzyme (ACE) inhibitors during stress, the cardiovascular response to various stress tests was examined in patients with essential hypertension before and after three months of therapy with lisinopril. Eighteen white patients were enrolled in the trial, of whom 12 completed the protocol. ACE inhibition with lisinopril effectively reduced systolic and diastolic pressure in the office (P less than 0.001), at rest (P less than 0.002), during mental stress (P less than 0.003), cold pressor test (P less than 0.003), and reaction time task (P less than 0.05). During physical exercise only diastolic pressure was significantly reduced (P less than 0.02). The fall in peak systolic pressure during cold pressor test and reaction time task was more pronounced than the fall in casual systolic pressure (P less than 0.05). At rest, cardiac output was unchanged, but total peripheral resistance was reduced after medication with lisinopril (P less than 0.05). During the cold pressor test, the increase in total peripheral resistance was attenuated by ACE inhibition (P less than 0.04). The haemodynamic response profile was not altered during the other tests. It is concluded that in middle-aged men ACE inhibitors reduce blood pressure during a variety of stressful events without altering the haemodynamic profile and even attenuating vasoconstriction during stress. This response pattern to ACE inhibition with lisinopril may reduce the impact of recurring stress-induced increases of blood pressure and of exaggerated vasoconstrictive stimuli on the cardiovascular system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Pharmacological modulation of stress-induced cardiovascular hyperreactivity in essential hypertension.

The effects of the calcium antagonist isradipine and the beta-blocker metoprolol, which are based on different antihypertensive therapeutic principles, were evaluated in 52 men with mild-to-moderate hypertension in a 6-week, double-blind, randomized study. Mental stress-testing was performed before and after active treatment. With isradipine (n = 26), the stress-induced responses of cardiac output and total peripheral resistance were not significantly changed, but the blood pressure (BP) response, specifically the diastolic response, was decreased. With metoprolol (n = 26), there was a decreased response of cardiac output and an increased response of total peripheral resistance, and the BP response was even greater than it had been before treatment. Thus, these results indicate that beta-blockade is effective in reducing cardiac responsiveness but, because of vascular counterregulatory mechanisms, BP responsiveness is not decreased. In contrast, calcium antagonism preserves the physiological hemodynamic profile while reducing BP responsiveness to stress.

Calcium Channel Blockers↗
PubMed1992

[Long-term 24-hour blood pressure measurement in genuine gestosis and hypertensive pregnancy].

The clinical implications of diminished circadian blood pressure variations during hypertensive pregnancies are not fully understood. We used the COS-INOR-method to quantify circadian blood pressure amplitudes of 32 patients with preeclampsia (GG) and 21 patients with superimposed pre-eclampsia (PG). The two groups did not significantly differ in body weight, age, and gestational date at admission. No differences could be detected in 24-h blood pressure values between the two groups (GG: 127 +/- 14/82 +/- 12 mmHg, PG: 128 +/- 16/86 +/- 9 mmHg). Circadian amplitudes of systolic blood pressure variations (GG: 5.9 +/- 5.5 mmHg, PG: 4.5 +/- 6.9 mmHg) and diastolic blood pressure variations (GG: 3.8 +/- 3.0 mmHg, PG: 5.3 +/- 4.1 mmHg) did not differ significantly. The slope between successive changes of mean arterial blood pressure and successive changes in heart rate was significantly higher in patients with superimposed pre-eclampsia (GG: 0.16 +/- 0.27 mmHg/bpm, PG: 0.36 +/- 0.24 mmHg/bpm, p less than 0.005). We conclude that patients with pre-eclampsia and superimposed pre-eclampsia do not differ in 24-h blood pressure and circadian blood pressure variability, however, if blood-pressure variability is related to heart-rate variability differences become apparent that might be due to altered blood-pressure regulation.

Adult↗
PubMed1991

Impact of dilevalol on haemodynamic changes during emotional stress.

The effect of a single dose of 200 mg dilevalol, beta-adrenoceptor blocker with additional vasodilating properties, and 200 mg oxprenolol on haemodynamic changes induced by emotional stress have been compared in 12 male young Caucasian patients with newly diagnosed labile hypertension. No difference was noted in the stress-induced increase of total peripheral resistance (TPR) following administration of the two substances (11% versus 6%). However, dilevalol revealed a vasodilating action by decreasing TPR at rest (from 1004 to 951 dyn.s.cm-5) and diastolic blood pressure (BP) (from 87 to 75 mm Hg) whereas TPR at rest remained unchanged after the intake of oxprenolol.

Blood Pressure↗
PubMed1991

Elevated serum activity of N-acetyl-beta-glucosaminidase in essential hypertension: diagnostic value and reversal to normal values after antihypertensive therapy.

Previous studies have shown that urinary N-acetyl-beta-glucosaminidase (NAG) is elevated in patients with hypertension, even without renal disease. To elucidate the value of measuring NAG, both in urine and serum of hypertensive patients, we measured NAG activity in the serum, plasma, and 24-hour urine by the fluorimetric method in 84 patients with uncomplicated essential hypertension before and after 6 months of effective treatment. NAG activities of these hypertensive patients were compared with those of 102 healthy normotensive subjects and 97 patients with various renal diseases and controlled hypertension. Serum NAG activity was clearly greater in patients with essential hypertension (427 +/- 124 U/mL) than in normotensive subjects (380 +/- 109 U/mL) or patients with renal disorders (393 +/- 115 U/mL) (P less than or equal to 0.004). The greater was the diastolic pressure in the hypertensive group, the greater was serum NAG activity (r = +0.30, P = 0.004). Hypertensive patients with high serum NAG activity were further characterized by a more exaggerated increase in systolic pressure (34 +/- 16 v 25 +/- 15 mm Hg, P = 0.051) and total peripheral resistance (19% +/- 18% v 12% +/- 13%, P = 0.042) in response to the cold pressor test and by a greater increase in systolic pressure (56 +/- 15 v 45 +/- 13 mm Hg, P = 0.009) and diastolic pressure (11 +/- 7 v 6 +/- 9, P = 0.043) in response to bicycle exercise testing than the group with low serum NAG activity. In contrast, urinary NAG activity tended to be only slightly higher in patients with essential hypertension than in the normotensive control group (33 +/- 31 v 23 +/- 29 U/mg creatinine [cr], P = 0.062), whereas patients with renal diseases had clearly increased urinary NAG activity (87 +/- 105 U/mg cr) (P less than 0.001). Following effective antihypertensive therapy, serum NAG activity decreased in patients with essential hypertension to values of normotensive control subjects (from 427 +/- 124 U/mL to 386 +/- 106 U/mL, P less than 0.01). A significant decrease in serum NAG activity was observed in patients with both initially high as well as low pretreatment serum NAG activities (P less than 0.001 and P less than 0.02, respectively). Urinary NAG activity overall was unchanged by antihypertensive treatment. We conclude that in patients with mild essential hypertension, serum NAG activity was already elevated (whereas urinary NAG activity was not) and was normalized by effective antihypertensive treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylglucosaminidase↗
PubMed1991

Changes in sympathetic and parasympathetic cardiac activation during mental load: an assessment by spectral analysis of heart rate variability.

Spectral analyses of heart rate (HR) and blood pressure (BP) fluctuations yield three typical peaks at a low (0.02-0.06 Hz), a mid (0.07-0.14 Hz) and a high (around the respiratory frequency) frequency area. These so-called bands attract the interest of researchers because they seem to offer the facility of non-invasively studying autonomic cardiovascular control mechanisms. The high frequency component is solely under vagal control, the influence of sympathetic/vagal efferents on the low and mid frequency band is unclear. We therefore investigated in a single case study (23 year old male) the effects of propanol (0.06 mg/kg, 30 min. interruption, 0.12 mg/kg i.v.), dobutamine (1.14 micrograms/kg/min for 30 minutes, then 2.21 micrograms/kg/min i.v., then 4.42 micrograms/kg/min), atropine (0.01 mg/kg within 5 minutes, 30 minutes later 0.02 mg/kg within 5 minutes), and carbachol (0.125 mg, 30 min. interruption, 0.25 mg s.c.) upon HR, HR-variability spectra, BP and respiratory parameters at rest and during 5 minutes of a mental task. Under all four drug conditions BP is elevated at rest and mental stress, the latter always giving higher results than the former. Atropine shortens interbeat intervals (IBI) by almost 50 percent (from 939 msec to 514 msec), the high dose of dobutamine reduces IBI from 725 to 580 msec, propranolol increases interval length by 10 percent. Drug effects on spectral bands give clear results with atropine: It reduces spectral energy in all three frequency bands at rest and during mental stress. The other drugs show no clear-cut effects on HR-variability spectra. Even though results of a single case study should be interpreted with great caution we believe that the following conclusion can be made: At rest and during short-lasting mental stress all frequency bands in HR-variability spectra are to a large extent under parasympathetic control.

Adult↗
PubMed1991

On the usefulness of finger blood-pressure measurements for studies on mental workload.

Two experiments were conducted to explore the usefulness of the Penaz method for non-invasive, continuous finger blood pressure measurements during mental stress testing. In the first study, blood pressure was measured with the Penaz method, in the second it was measured intra-arterially. Two different subject groups were used. In both experiments the same mental task, a memory search and counting task, was used. Experimental effects, consisting of rest-task differences in heart rate and blood pressure, its (spectral) variability and the coherence between fluctuations in the two signals (e.g. baroreflex sensitivity) are compared for the two measuring methods. Experimental effects on mean pressure values, spectral variability measures and baroreflex sensitivity are similar for the two types of measurement. Effects on mean pressure are smaller in the finger pressure indices. It is concluded that the Penaz instrument can provide us with a useful method for studying cardiovascular reactivity in mental stress research.

Adolescent↗
PubMed1990

[Psychotropic effects of captopril? Effect of a short-term treatment on reaction and concentration capabilities and space perception ability].

In a randomized, placebo-controlled double-blind trial 22 healthy normotensive young men (mean age 25 +/- 1.7 years) were given a single oral dose of 50 mg captopril or a placebo (11 subjects each). To test their concentration and proficiency, as well as spatial perception and reaction capacity four tests were administered: attention, concentration, hose-pattern perception and "Bonn Determination Device". Captopril had no negative effects on any test performances either one or five hours after its administration, or after a single daily dose for seven days. There was only a small, statistically not significant, difference in the effect on blood pressure between captopril and the placebo.

Adult↗