W. Schulte

Basal blood pressure variability and reactivity of blood pressure to emotional stress in essential hypertension

SummaryBlood pressure variability under basal conditions and blood pressure reactivity to emotional stress were studied in 38 hypertensives and 13 normotensives.Systolic basal blood pressure variability correlated with systolic blood pressure reactivity. Variability increased with higher basal blood pressure. Thus in the hypertension group the blood pressure variability was greater than in the normotension group. Besides, the hypertension group showed a greater reactivity of systolic blood pressure to emotional stress, too. An influence of age on basal blood pressure, blood pressure variability, and reactivity could be evaluated; but no influence of sex on these parameters was detected.The results indicate that variability and reactivity of blood pressure can be referred to a common central nervous blood-pressure-regulating mechanism. As both parameters are increased in hypertension, a greater lability of blood pressure must be assumed. This greater lability may be attributed to a stronger neurogenic influence or to structural changes of peripheral blood vessels.

The Importance of Cardiovascular Reactivity to Different Types of Stress for the Development of Hypertension

Cardiovascular reactivity to emotional stress has been investigated in a series of studies relating to the general hypothesis linking stress with essential hypertension. Increased blood pressure reactivity to mental stress (mental arithmetic in the presence of distracting noise) was observed in established hypertensives, and in prehypertensive states as well. Hyperreactivity in prehypertensive states did not, however, occur in response to the cold pressor test. The different haemodynamic patterns underlying responses to these tests may account for this discrepancy. It is concluded that blood pressure hyperreactivity in prehypertensive states will only be exhibited in response to mental stress tests that induce prominent cardiac reactivity. Pharmacological studies give support to the notion that increased sympathetic drive may be responsible for this cardiovascular reactivity. It is concluded that heightened blood pressure responses under emotional stress may be significant in the development of hypertension.

Hemodynamic and neurohumoral effects of low-dose clonidine in mild to moderate hypertension.

&NA; To evaluate the role of the sympathetic nervous system in essential hypertension and the influence of clonidine, 28 male subjects with mild to moderate hypertension were either treated with low‐dose clonidine (n = 14, mean age: 42.4 ± 2.1 years) or were randomized to a nontreated control group (n = 14, mean age: 40.2 ± 2.4 years). Clinical blood pressure and heart rate were assessed, and after 4 weeks of treatment plasma catecholamines and the hemodynamic response to mental arithmetic, cold stimulation, and ergometric exercise were compared between both groups. Under therapy with 0.075 mg of clonidine per day casual blood pressure dropped and diastolic BP was significantly lower than in the control group. Heart rate did not change. After 4 weeks the plasma levels of epinephrine and norepinephrine were the same in both groups. During mental arithmetic total peripheral resistance decreased in the treated group while it did not change in the control group, but both groups did not differ in their percentage changes in the hemodynamic parameters in response to the three stress tests. It has been concluded that clonidine reduces sympathoadrenergic activity, but in a low dosage this effect is obviously restricted to a reduction of arteriolar tone.

Blutdruckreaktivität unter emotionalem Streß bei unkomplizierten Formen des Hochdrucks

SummaryBlood pressure behavior under basal conditions and emotional stress was examined in 48 patients with elevated casual blood pressure values who had no hypertensive cardiovascular complications and in 48 normotensives of the same age. In order to study possible interactions with age and sex each group was divided in two age and two sex subgroups respectively.Under basal conditions the blood pressure values of the hypertensive group were within the normal range but markedly higher than the values of the normotensive group. During stress the difference between both groups increased because the hypertensive group exhibited a stronger reactivity of blood pressure. There was an interaction between sex and hypertension in that in contrast to the hypertensive group normotensive women had lower blood pressure values at rest and under emotional stress than men. There was an influence of age consisting in a stronger blood pressure reactivity of the older subjects; this effect could be found in the hypertensive as well as in the normotensive group.Patients with uncomplicated forms of hypertension exhibit a blood pressure hyperreactivity on emotional stress independendly of age and sex. According to previous investigations normotensive subjects with a family history of hypertension show stronger blood pressure reactivity, too. Therefore this phenomenon must be regarded as important in the pathogenesis of essential hypertension.ZusammenfassungBei 48 Patienten mit erhöhten Gelegenheitsblutdruckwerten ohne hypertoniebedingte kardiovaskuläre Komplikationen und 48 altersgleichen normotonen Vergleichsprobanden wurde das Blutdruckverhalten unter strengen Ruhebedingungen und emotionalem Streß untersucht. Um dabei gleichzeitig mögliche Wechselwirkungen mit Alter und Geschlecht zu erfassen, wurden die beiden Gruppen in jeweils zwei Alters- und zwei Geschlechtsgruppen unterteilt.Die hypertone Gruppe wies unter strengen Ruhebedingungen zwar einen im Normbereich liegenden Blutdruck auf; dieser lag aber deutlich höher als bei der normotonen Gruppe. Während der Streßphase war dieser Unterschied noch deutlicher ausgeprägt, da die hypertone Gruppe einen stärkeren Blutdruckanstieg auf den emotionalen Streß zeigte als die normotone Gruppe. Eine Wechselwirkung zwischen Geschlecht und Hypertonie bestand insofern, als normotone Frauen in Ruhe und während Belastung einen niedrigeren Blutdruck aufwiesen als normotone Männer, in der hypertonen Gruppe aber keine Geschlechtsunterschiede des Blutdrucks bestanden. Ein Alterseffekt war in der bei den älteren Probanden verstärkten Blutdruckreaktivität feststellbar; dieser Effekt war sowohl bei der normotonen wie bei der hypertonen Gruppe zu finden.Personen mit unkomplizierten Formen des Hochdrucks weisen also unabhängig von Alter und Geschlecht eine Blutdruckhyperreaktivität unter emotionalem Streß auf. Da nach früheren Untersuchungen auch bei normotonen Personen mit einer hereditären Hypertoniebelastung die verstärkte Blutdruckreaktivität besteht, muß diesem Phänomen eine besondere Bedeutung in der Pathogenese der essentiellen Hypertonie zugemessen werden.

Der Einfluß von experimentellem Verkehrslärm auf vegetative Funktionen von Normotonikern und Hypertonikern nach Streß

In a series of experiments on 12 normotensives and 12 essential hypertensives the influence of traffic noise (81 dB) on autonomous functions after stress exposure was examined. The process of the stress reaction was started by visually presented arithmetic tasks under affecting noise. With normotensives and hypertensives this combination of stressors led to a significant increase of the systolic and diastolic blood pressure, heart rate, and muscle tone. The influence of traffic noise directly following the combination of stressors was examined in an intraindividual comparison with a resting-time period. During the period of noise, significantly higher values with blood pressure data only were found with normotensives and hypertensives as well. The comparison between the normotensive and the hypertensive group during the combination of stressors and during the following resting period showed no significant differences in reaction whereas during the second stressor hypertensives compared to normotensives showed strong, partly significant adaptation reactions of blood pressure with regard to the preceding experimental phase.SummaryIn a series of experiments on 12 normotensives and 12 essential hypertensives the influence of traffic noise (81 dB) on autonomous functions after stress exposure was examined. The process of the stress reaction was started by visually presented arithmetic tasks under affecting noise. With normotensives and hypertensives this combination of stressors led to a significant increase of the systolic and diastolic blood pressure, heart rate, and muscle tone.The influence of traffic noise directly following the combination of stressors was examined in an intraindividual comparison with a resting-time period. During the period of noise, significantly higher values with blood pressure data only were found with normotensives and hypertensives as well.The comparison between the normotensive and the hypertensive group during the combination of stressors and during the following resting period showed no significant differences in reaction whereas during the second stressor hypertensives compared to normotensives showed strong, partly significant adaptation reactions of blood pressure with regard to the preceding experimental phase.ZusammenfassungIn einer Versuchsreihe von 12 Normotonikern und 12 essentiellen Hypertonikern wurde untersucht, wie sich der Einfluß von Verkehrslärm (81 dB) nach vorausgegangenem Streß auf vegetative Funktionen auswirkt. Der Streß wurde durch einen optisch dargebotenen Rechentest unter affektiver Belärmung ausgelöst. Dieser kombinierte Stressor führte bei Normotonikern und Hypertonikern zu signifikanten Anstiegen des systolischen und diastolischen Blutdrucks, der Herzfrequenz und des Muskeltonus.Der Einfluß des Verkehrslärms im unmittelbaren Anschluß an den kombihierten Stressor wurde durch intraindividuellen Vergleich zu einer zeitlich entsprechenden Ruhephase geprüft. Signifikant höhere Werte während der Belärmung fanden sich sowohl bei Normotonikern wie bei Hypertonikern nur bei den Blutdruckwerten.Der Vergleich der normotonen und hypertonen Gruppe ergab keine signifikanten Unterschiede des Reaktionsverhaltens während des kombinierten Stressors und während der anschließenden Erholungsphase. Hingegen zeigten Hypertoniker während des zweiten Stressors im Vergleich zu Normotonikern deutliche, teilweise signifikante Adaptationsreaktionen des Blutdrucks im Verhältnis zu der vorausgegangenen Versuchssituation.

Hemodynamic abnormalities in borderline hypertension during mental stress

Cardiovascular reactivity to mental stress was studied in 41 male borderline hypertensives in comparison with 37 male normotensives of the same age. In addition to a higher near-basal blood pressure, the borderline hypertensive group showed stronger absolute and percentage increases of systolic and diastolic blood pressure during stress. The increases of heart rate and cardiac output and the decreases of total peripheral resistance were also greater in borderline hypertensives. Stroke volume showed a slight increase only in this group. The reaction of mean arterial pressure correlated in both groups with the increase of cardiac output. The relationship between the reactions of cardiac output and total peripheral resistance was high both in normotensives and borderline hypertensives, and the regression line in normotensives was shifted to the right in borderline hypertensives. The results indicate an increased integrated change of circulatory parameters during mental stress in borderline hypertension, with a dominantly stronger cardiac reaction. They underline the significance of an autonomic imbalance for the pathogenesis of borderline hypertension.

Bedeutung der Mikroproteinurie zur Früherkennung hypertoniebedingter Endorganschädigungen

SummaryTo investigate the clinical importance of microproteinuria, we examined the prevalence of microproteinuria and its relation to cardiac structural adaptation in 80 male, middle-aged patients with essential hypertension. Patients with secondary causes of hypertension were ruled out.14 out of 80 hypertensives (18 percent) were found to have microproteinuria defined as “negative” for urinary protein excretion in the conventional test, but “positive” (above the upper normal limit) in the 24-hour urine samples. Patients with microproteinuria had a similar age and body weight, but a higher systolic and diastolic pressure (161±14/104±12 vs 148±14/97±9 mmHg,p< 0.02) and greater creatinine clearance (163±36 vs 136±33 ml/min,p<0.01) than those with normal protein excretion. Also, hypertensives with microproteinuria had a greater left ventricular mass (241±57 vs 207±45 g,p<0.05) and greater cross sectional area (22.2±2.8 vs 20.5±2.9 cm2,p< 0.05) evaluated by 2-D guided M-mode echocardiography than the control group. A positive Sokolow-index was more prevalent in patients with microproteinuria than in those without (x2=6.2,p<0.02).Patients with essential hypertension and microproteinuria (prevalence 21 per cent) were characterized by a higher arterial pressure, by a higher degree of echocardiographic and electrographic evidence of left ventricular hypertrophy. Thus, microproteinuria might serve as a marker for early target organ damage in essential hypertension.

Cardiovascular reactivity to methacholine in normotensives with genetic risk of hypertension.

Hemodynamic reactivity to methacholine (0,1 mg/kg bodyweight) was studied in 10 normotensives with genetic risk of hypertension (mean age: 25,4 +/- 2,6 years) in comparison with 8 controls (mean age: 25,0 +/- 2,3 yrs). Due to peripheral vasodilatation this substance led to an initial blood pressure fall which was the same in the investigated and in the control group. In the phase of counterregulation the secondary rise of blood pressure was higher in the group with family history of hypertension. As evidenced by correlation statistical analysis the increases of heart rate and cardiac output were responsible for the rise of systolic blood pressure. The hemodynamic response to methacholine in the group with genetic risk of hypertension has been attributed to a higher sympathetic reactivity.

Relationship between blood pressure reactions on an ergometric and an emotional stress test

SummaryThe relationship between blood pressure reactions on an ergometric and an emotional stress test was studied in a population of 62 normotensive subjects. Significant correlations for systolic (r=0.34,p=0.004) and diastolic (r=0.30,p=0.01) blood pressure were found.It is concluded that 1) there is a individual-specific blood pressure reactivity, 2) Hypertension is closely related to the individualspecific systolic blood pressure reactivity for it is known that hypertensives exhibit stronger systolic blood pressure reactions on both stressors.ZusammenfassungDer Zusammenhang zwischen den Blutdruckreaktionen auf eine ergometrische und eine emotionelle Streßbelastung wurde bei 62 normotonen Probanden untersucht. Es wurden für systolischen (r=0,34,p=0,004) und diastolischen (r=0,30,p=0,01) Blutdruck signifikante Korrelationen gefunden.Es wurde geschlossen 1) daß es eine individualspezifische Blutdruckreagibilität gibt, 2) daß Hypertonie eng mit der individualspezifischen systolischen Blutdruckreaktivität zusammenhängt, da bekannt ist, daß Hypertoniker auf beide Stressoren eine stärkere systolische Blutdruckreaktivität aufweisen.

Pharmacological modulation of stress-induced cardiovascular hyperreactivity in essential hypertension

The effects of the calcium antagonist isradipine and the β-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 β-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.