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Biomedical subjects

H Schächinger

Publications and source records attributed to H Schächinger.

At least 37 records · Page 2Linked to original sources
PubMed1994

Accelerated decline in renal perfusion with aging in essential hypertension.

The present cross-sectional study was designed to assess the effect of the severity of hypertensive cardiovascular disease and age on renal hemodynamics. In a homogeneous population of 157 white men (aged 15 to 87 years), we assessed renal and systemic hemodynamics by measuring mean arterial pressure invasively, renal blood flow by 131I-para-aminohippuric acid clearance, and cardiac output by the indocyanine dye dilution technique. Stepwise multiple regression analysis revealed the following independent determinants of renal blood flow: age (beta = -.42, P < .001), height (beta = +.14, P < .03), mean arterial pressure (beta = -.15, P < .02), and cardiac output (beta = +.19, P < .008). Renal blood flow corrected for height correlated inversely with age in all three groups. However, the renal fraction of cardiac output did not correlate with age in borderline hypertension (r = .17, P = NS) and in normotension (r = .12, P = NS), suggesting a parallel decline in renal blood flow and cardiac output with aging. In contrast, in established hypertension, the renal fraction of cardiac output was closely linked to age (r = .52, P < .001) and significantly steeper (P < .01) than in normotension or borderline hypertension. We conclude that unlike in normotensive subjects or patients with borderline hypertension, patients with established hypertension have an accelerated decline in renal perfusion with aging, reflecting selective functional or structural changes or both in the renal vascular bed.

Adolescent↗
PubMed1994

Renal hemodynamic response to stress is influenced by ACE-inhibitors.

Cardiovascular responses to new antihypertensive agents have been studied extensively under resting and stress conditions. However, the effects of antihypertensive agents on renal hemodynamics have only been investigated at rest. To test whether antihypertensive therapy leads to disparate renal hemodynamic effects during exposure to mental stress as opposed to resting conditions, we performed a double-blind, placebo-controlled crossover study. In 17 normotensive healthy men, glomerular filtration rate (GFR; inulin clearance) and renal plasma flow (RPF; para-aminohippuric acid clearance) were measured at rest and after a standardized mental stress test, with or without one week's treatment with a new, long-acting ACE-inhibitor cilazapril 2.5 mg/day. ACE-inhibition did not change resting blood pressure, RPF, GFR, or derived parameters, such as filtration fraction, renal vascular resistance and renal fraction of cardiac output. Mental stress caused an acute increase in GFR (p < 0.001) and filtration fraction with both treatments (0.001). However, the increase in GFR and filtration with mental stress was greater (p < 0.05) with cilazapril treatment than with placebo. Thus, renal hemodynamic responses to mental stress were influenced by ACE inhibitors. We conclude that the impact of antihypertensive agents on renal hemodynamics during stress cannot a priori be delineated from measurements at rest.

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

Stress response pattern in obesity and systemic hypertension.

Under resting conditions obese hypertensive patients have been described as having a greater cardiac output and lower total peripheral resistance than lean hypertensive patients. To evaluate the hemodynamic patterns under stress conditions, we determined the hemodynamic response to mental stress (first study) and during isometric exercise (second study) in hypertensive patients with a body mass index > 27 kg/m2 (obese) and < 27 kg/m2 (lean). The cohort exposed to mental stress comprised 54 white male patients (30 were lean, 24 were obese) with untreated stage I or II essential hypertension according to the World Health Organization. Obese subjects responded with a higher increase in total peripheral resistance (p < 0.02) and lower increases in heart rate (p < 0.01), cardiac output (p < 0.01) and stroke volume (p < 0.02) when compared with their lean counterparts. This was independent of any differences in chemical or baseline hemodynamic characteristics at rest. The cohort exposed to isometric stress consisted of 57 patients (30 were lean, 27 were obese) with World Health Organization stage I or II essential hypertension. Obese subjects responded with exaggerated increases in systolic (p < 0.04) and diastolic (p < 0.01) pressures, and heart rate (p < 0.04) when compared with lean patients. Body mass index emerged as an independent determinant of the increase in systolic (r = 0.03) and diastolic (r = 0.01) pressure as well as of heart rate (r = 0.03). These results indicate that obese hypertensive patients respond to (1) mental stress with vasoconstriction instead of the expected vasodilation, and to (2) isometric stress with an exaggerated increase in arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
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

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

[Importance of 24-hour blood pressure monitoring in detection of hypertension-induced end organ damage].

Casual blood pressure does not provide an adequate estimation for the hemodynamic load of 24 hours upon the cardiovascular system. Hence, cardiovascular complications are loosely correlated to casual blood pressure measurements in arterial hypertension. In contrast, ambulatory blood pressure measurements have been repeatedly found to be closely related to signs of target organ damage such as left ventricular hypertrophy, hypertensive nephropathy and impaired arterial compliance. Furthermore, monitoring of blood pressure over 24 hours allows assessment of hazardous nocturnal declines in perfusion pressure with the risk of fatal coronary or cerebrovascular events. A blunted nocturnal decline in blood pressure has been suggested to indicate secondary forms of arterial hypertension or severe hypertensive disease. In conclusion, ambulatory blood pressure monitoring, nowadays reliably assessed by non-invasive tools, improves the estimation of the hemodynamic load imposed on the cardiovascular system and thereby the risks attributed to arterial hypertension.

Blood Pressure↗
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↗
PubMed1990

Relation of hemodynamic reaction during stress to left ventricular hypertrophy in essential hypertension.

To elucidate the impact of increased afterload during physical and mental stress on myocardial hypertrophy, a homogeneous population of 73 patients with untreated mild-to-moderate essential hypertension were enrolled in the current study. Left ventricular mass and cross-sectional area, both determined by 2-D guided M-mode echocardiography, were related to blood pressure measured at rest as well as during various stress situations. Left ventricular mass and cross-sectional area correlated with systolic pressure at work site (r = 0.28 and r = 0.23 respectively, P less than .05) and systolic pressure at complete rest (r = 0.35 and r = 0.33, P less than .01). Neither the response in blood pressure to mental arithmetic or a bicycle exercise test performed in the laboratory, nor blood pressure during both stress tests were significantly related to the degree of left ventricular hypertrophy. In addition, patients with a hyperreactive response to mental arithmetic or to the physical stress test did not disclose a greater left ventricular mass than normoreactors. Examining the hemodynamic response pattern during mental arithmetic, we found that patients with vasoconstriction during mental stress had a greater left ventricular mass than individuals with vasodilation during mental stress (244 +/- 73 v 204 +/- 53 g, P less than .05), but this was due to the impact of obesity on left ventricular mass (analysis of covariance: F = 2.1, P = NS). Thus, blood pressure at work site and at rest, but not blood pressure during mental or physical stress, nor the response of blood pressure to both stress tests, was linked to the degree of left ventricular hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomegaly↗
PubMed1990

Efficacy of long-term antihypertensive therapy with enalapril.

We examined whether long-term antihypertensive monotherapy with enalapril decreased clinical casual blood pressure (BP) as well as BP at work and during stress, and whether this angiotensin-converting enzyme (ACE) inhibitor had an adverse effect on the physiologic hemodynamic pattern during experimental mental stress. Seventeen male patients with hitherto untreated mild-to-moderate essential hypertension (mean age: 47 +/- 8 years) had 24-hour BP monitored noninvasively with the Physioport system before and during treatment with enalapril (5-10 mg/day) for 6 months. They also had a mental stress test, physical exercise test, and the cold pressor test before and after therapy. After the diagnostic observation period, average clinical casual BP was 150 +/- 12/102 +/- 7 mg Hg. Average BP at work, stress BP during all types of stimulation in the laboratory, and clinical casual BP significantly decreased during monotherapy with enalapril. Neither the circadian rhythm nor the hemodynamic pattern during mental stress was significantly altered by enalapril. BP increases during emotional stress were not significantly attenuated by the ACE inhibitor. These results demonstrated that enalapril effectively lowers BP without altering the physiologic hemodynamic pattern during emotional stress.

Adult↗
PubMed1989

Efficacy of four antihypertensive drugs (clonidine, enalapril, nitrendipine, oxprenolol) on stress blood pressure.

The impact of 4 antihypertensive drug regimens on blood pressure (BP) during everyday life stress and on BP during experimental stress in the laboratory was examined in an open clinical study. Sixty middle-aged men with mild-to-moderate essential hypertension never previously treated were treated either with low-dose clonidine (n = 10), oxprenolol (n = 20), nitrendipine (n = 20) or enalapril (n = 10). Before therapy, all 4 groups did not differ in age, weight, degree of obesity, BP at work site and casual BP measured in the outpatient clinic. After 6 months of effective therapy (casual BP within the normotensive range), casual diastolic BP was identical among the 4 groups, whereas systolic BP was lower in patients treated with clonidine or oxprenolol than in those who received enalapril. A disparate pattern of antihypertensive efficacy among the 4 groups emerged when stress BP was compared, with average ambulatory BP higher in patients receiving clonidine or enalapril than in those who had oxprenolol or nitrendipine. During ambulatory BP monitoring, patients treated with oxprenolol had the lowest level at each level of physical activity and self-reported emotional arousal. During bicycle exercise, patients receiving clonidine had the highest increase in systolic BP and those administered oxprenolol the lowest, whereas the BP response during mental stress was similar among all 4 therapeutic groups. The analysis of the hemodynamic response pattern during mental stress unmasked further disparities. Oxprenolol provoked an abnormal hemodynamic response during mental stress tests (increase in total peripheral resistance), whereas nitrendipine and enalapril preserved the physiological hemodynamic profile (decrease of total peripheral resistance).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗