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 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In patients with hyperkinetic heart syndrome we found at rest a higher heart rate, a higher stroke volume and a higher cardiac output than in normal volunteers. Therefore blood pressure is high although peripheral resistance is lower than in normals. Similar circulatory differences were found under conditions of mental stress. After beta-adrenergic blockade with 15 mg Propranolol heart rate and cardiac output decrease, whereas peripheral resistance increases. Mean blood pressure thus remains unchanged. Even after beta-adrenergic blockade circulatory differences between normals and patients with hyperkinetic heart syndrome are seen. The possible causes of these differences are discussed.
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PMID:[Hemodynamics in patients suffering from hyperkinetic cardiac syndromes and in normal persons under psychological stress before and after treatment with propranolol (author's transl)]. 22 Aug 9

Information obtained during the past decade suggests that the onset of myocardial infarction and sudden cardiac death is frequently triggered by daily activities. The importance of physical or mental stress in triggering coronary thrombosis is supported by finding that (1) the frequencies of the onset of myocardial infarction, sudden cardiac death, and stroke show marked circadian variations, with similar increases in the period from 6 AM to noon; (2) the frequency of transient myocardial ischemia shows a similar increase in the morning, and episodes are often preceded by mental or physical triggers; (3) a ruptured atherosclerotic plaque, often nonobstructive by itself, lies at the base of most coronary thrombi; (4) a number of physiologic processes that could lead to plaque rupture, a hypercoagulable state, or coronary vasoconstriction, are accentuated in the morning; and (5) aspirin and beta-adrenergic blocking agents that affect certain of these processes have been shown to prevent disease onset. The hypothesis presented is that occlusive coronary thrombosis occurs when (1) an atherosclerotic plaque becomes vulnerable to rupture; (2) mental or physical stress causes the plaque to rupture; and (3) increases in coagulability or vasoconstriction, triggered by daily activities, contribute to complete occlusion of the coronary artery lumen. Recognition of the circadian variation--and the possibility of frequent triggering--of the onset of acute disease suggests the need for pharmacologic protection of patients during the vulnerable periods and provides clues to the mechanism of disease onset, the investigation of which may lead to improved methods of prevention.
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PMID:Triggering and hourly variation of onset of arterial thrombosis. 134 90

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)
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PMID:Stress response pattern in obesity and systemic hypertension. 141

The purpose of this study was (1) to evaluate the technical and methodological problems associated with invasive haemodynamic measurements in unsedated cattle; (2) to assess the reproducibility of such measurements both within and between days; and (3) to compare the values with those previously reported. Twenty-one healthy calves, aged from 5.5 to 12 months, were studied. The central venous, the right ventricular, the pulmonary arterial, the pulmonary capillary wedge and the systemic arterial pressures were obtained by means of fluid-filled catheters, and the cardiac output was measured by the thermodilution technique. The heart rate, the stroke volume, the pulmonary and systemic vascular resistances and the pulmonary and systemic ventricular workloads were calculated. An adverse reaction, consisting of severe pulmonary hypertension, tachycardia, tachypnoea and transient weakness, occurred in 7 calves during the catheterization procedures. Such a reaction might be due to a local reflex induced by stimulation of mechano-receptors by the catheter tip. It should be avoided by reducing the manipulation of the catheter as much as possible and by inflating the tip of the balloon when moving it forwards. A comparison of the vascular pressures with those previously reported was difficult because of methodological or technical limitations, such as, for instance, a lack of standardization of the baseline. The reproducibility of the haemodynamic measurements obtained was satisfactory, in contrast to previous studies performed in conscious animals. This was attributed to our animals being better trained to the experimental conditions and emphasizes the importance of reducing mental stress in obtaining reliable haemodynamic measurements in unsedated and potentially uncooperative animals.
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PMID:Technical and methodological requirements for reliable haemodynamic measurements in the unsedated calf. 149 63

The possible relationship between mental stress-induced cardiovascular reactivity and clinical prognosis was examined in a pilot study of 13 postinfarction patients. All patients had previously participated in the placebo condition of a secondary intervention trial. On completion of the trial, blood pressure, heart rate, and venous plasma catecholamines were evaluated at rest and in response to a modified Stroop test on two occasions. At follow-up 39 to 64 months later, five patients had suffered a new clinical event (reinfarction and/or stroke). These patients had shown significantly larger systolic and diastolic blood pressure responses to the Stroop test than had patients who remained event-free at follow-up. Catecholamine concentrations also differed between groups during mental stress, but on only one of the two test days. Groups did not differ on baseline measurements, cardiovascular response to exercise testing, fasting serum lipid and glucose concentrations, age, or duration of follow-up.
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PMID:Does cardiovascular reactivity to mental stress have prognostic value in postinfarction patients? A pilot study. 155 97

Central obesity increases the risk for cardiovascular disease, but little is known about its hemodynamic effects. The aims were to investigate the influence of obesity (as defined by body mass index) and abdominal fat accumulation (as defined by the waist/hip ratio) on hemodynamics at rest and during mental stress. Invasive hemodynamic studies were performed in 20 healthy, normotensive young men (aged 18-22 years) recruited from an unbiased population sample. Their body mass index and waist/hip ratio ranged between 18.5 and 30.2 (mean 24.1) and 0.77 and 0.98 (mean 0.87), respectively. Hemodynamics were related to the two anthropometric indexes by bivariate regression analyses. Cardiac output and stroke volume were positively correlated to body mass index (p = 0.05 and p = 0.005), but inversely to waist/hip ratio (p = 0.01 and p = 0.01). Mental stress augmented the hemodynamic patterns. Total peripheral resistance during stress correlated inversely to body mass index (p = 0.02), whereas high waist/hip ratio was associated with higher systemic vascular resistance p = 0.002). The delta CO/delta MAP ratio, i.e., relative contribution of cardiac output for the stress-induced increase in mean arterial pressure, showed a strong positive association with body mass index (p = 0.004), but was inversely related to the waist/hip ratio (p = 0.002). Serum insulin correlated significantly to the stress-induced change in total peripheral resistance (r = 0.54; p = 0.02), whereas the increase in cardiac output was inversely related to insulin (r = -0.59; p = 0.007). Thus, central obesity is associated with a specific hemodynamic pattern characterized by higher total peripheral resistance, lower cardiac output, and a vasoconstrictor response to psychosocial stress.
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PMID:Relation of central hemodynamics to obesity and body fat distribution. 159 46

Cardiovascular hyperreactivity (i.e., response in excess of metabolic requirements) to psychological stress has been implicated in the development of coronary heart disease. The purpose of this study was to evaluate cardiovascular hyperreactivity to psychological stress in Type A and B subjects. Fifteen Type A and 15 Type B young men performed mental arithmetic and cycle ergometry tasks. Linear regressions were calculated for each dependent variable during exercise with oxygen uptake serving as the independent variable. All cardiovascular variables were significantly correlated (p less than .0001) with oxygen uptake during exercise. The regression equations obtained during exercise were then used to predict the value of each cardiovascular variable at the oxygen uptake level obtained during mental arithmetic for each person. Repeated measures ANOVA compared responses observed during arithmetic with responses predicted from exercise at an equivalent oxygen uptake in Type A and B subjects. Heart rate, total peripheral resistance, and mean arterial pressure were significantly greater (p less than .0001) and stroke volume was significantly lower (p less than .0002) during arithmetic than during exercise, while Heather index, cardiac output, and arteriovenous oxygen difference did not differ significantly. No significant differences were found between Type A and B males. Results demonstrated that cardiovascular hyperreactivity was equally robust across Type A and B subjects.
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PMID:Cardiovascular reactivity in Type A and B males to mental arithmetic and aerobic exercise at an equivalent oxygen uptake. 162 36

Left ventricular function was studied by M-mode echocardiography at rest and during a mental arithmetic stress test and a cold-pressor test in 14 patients with mild hypertension and in 14 matched normotensive subjects. The elevation of blood pressure at rest in the hypertensive group (154 +/- 4/87 +/- 3 vs. 120 +/- 3/66 +/- 3 mmHg in the control group) was due mainly to a higher cardiac output (6.0 +/- 0.3 vs. 5.0 +/- 0.3 L/min), which was related to elevations of stroke volume and heart rate (73 +/- 2 vs. 66 +/- 2 beats/min). Venous plasma catecholamines were similar in the two groups. Mental stress induced cardiac output-dependent increases in blood pressure in both groups; systemic vascular resistance tended to decrease. The relative increases in diastolic and mean arterial blood pressure were smaller in the hypertensive group (15 vs. 26% and 15 vs. 21%, respectively), which exhibited signs of a reduced cardiac compliance, possibly related to a left ventricular hypertrophy. Mental stress elevated venous plasma adrenaline similarly in the two groups; effects on noradrenaline were small. The cold-pressor test increased blood pressure similarly in the two groups, largely due to increased systemic vascular resistance; plasma noradrenaline responses were also similar. Mental stress appears to elicit a differentiated sympathetic nerve activation pattern resembling the hypothalamic defense reaction. Mild hypertension seems to be associated with increased arousal and cardiac activation at rest. However, an attenuated blood pressure reactivity to mental stress may reflect reduced stroke volume responsiveness, which is related to structural changes, as heart rate reactivity tended to be enhanced in mild hypertension.
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PMID:Stress-induced changes in blood pressure and left ventricular function in mild hypertension. 164 89

Cardiac output, heart rate, stroke volume, pre-ejection period, total peripheral resistance, systolic and diastolic blood pressure, and oxygen consumption were monitored or derived in young men with mildly elevated casual blood pressures and unambiguously normotensive control subjects before, during, and after exposure to a mental arithmetic stress. Measurements were also taken while subjects underwent graded dynamic exercise. This permitted cardiac output-oxygen consumption regression equations to be calculated and, as a consequence, cardiac output during mental stress to be represented as additional cardiac output. Systolic and diastolic blood pressure were higher during all phases of the study in the mildly elevated blood pressure group. An overall groups effect during the mental stress phase of the experiment was observed for cardiac output and pre-ejection period, and the effect for stroke volume was close to significance. Significant Groups X Periods interactions were found for cardiac output and additional cardiac output, and the heart rate effect was nearly significant. Post-hoc comparisons here indicated that, in the main, group differences in these cardiac variables were more evident during the mental arithmetic stress than during the pre- and post-task baseline periods. Total peripheral resistance did not differ reliably between groups and the cardiac effects were specific to the mental stress phase of the study.
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PMID:Haemodynamic adjustments to mental stress in normotensives and subjects with mildly elevated blood pressure. 174 23

Self-perceived psychological stress as a risk factor for coronary artery disease (CAD) was evaluated in a general population study comprising 6,935 men aged 47 to 55 years at baseline without previous myocardial infarction. In 1970 to 1973, the men answered a question about psychological stress defined as a feeling of tension, irritability or anxiety, or as having sleeping difficulties as a result of conditions at work or at home. Psychological stress was graded as follows: (1) never experienced stress; (2) greater than or equal to 1 period of stress; (3) greater than or equal to 1 period of stress during the last 5 years; (4) several periods of stress during the last 5 years; and (5 to 6) permanent stress during the last year or the last 5 years. After a mean follow-up of 11.8 years, 6% of the men with the lowest 4 stress ratings (n = 5,865) had either developed a nonfatal myocardial infarction or died from CAD, with no increase in risk from grade 1 to 4. The corresponding figure among the men with the highest 2 stress ratings (n = 1,070) was 10%; the odds ratio was 1.5 (95% confidence interval 1.2-1.9) after controlling for age and other risk factors. Similar, independent associations were seen with stroke, and with death from cardiovascular disease and from all causes, but not with death from cancer. With respect to CAD, no decrease in the effect of stress at baseline could be seen over time. No relation between life events and self-perceived psychological stress was found in another sample of 732 fifty-year-old men.
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PMID:Self-perceived psychological stress and incidence of coronary artery disease in middle-aged men. 195 Oct 76


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