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Biomedical subjects

T G Pickering

Publications and source records attributed to T G Pickering.

At least 91 records · Page 5Linked to original sources
PubMed1996

Self-efficacy as a component of active coping: effects on cardiovascular reactivity.

Active coping remains a poorly understood construct in cardiovascular reactivity testing. We have shown that active coping comprises two independent effects: the enhanced control and the effort of exercising control. The present study tested the proposition that, with effort left unconstrained, increased self-efficacy will increase cardiovascular response. Forty women were assigned to low or high self-efficacy conditions; self-efficacy was manipulated using false feedback. Subjects then engaged in a video game shape-matching task, while blood pressure and heart rate were monitored. SBP and DBP changes were smaller in the low self-efficacy group, as predicted: 17.9 versus 25.2 mmHG for SBP (p < 0.05); and 8.7 versus 13.0 mmHG for DBP (p = 0.07). Heart rate was similar for the two conditions. We conclude that self-efficacy for a task may be an integral part of the active coping process, indirectly affecting the blood pressure response by acting on the effort involved in the coping response.

Adaptation, Psychological↗
PubMed1996

Relation of arterial structure and function to left ventricular geometric patterns in hypertensive adults.

OBJECTIVES: The present study sought to determine whether conduit artery structure and function vary according to the pattern of left ventricular adaptation to hypertension. BACKGROUND: Although left ventricular geometric pattern has been shown to predict cardiovascular events in hypertension, the arterial status in patients with the different patterns is unknown. METHODS: We evaluated arterial structure and function by carotid ultrasound and applanation tonometry in 271 unmedicated hypertensive patients classified by echocardiography as having normal ventricular geometry (n = 176), concentric remodeling (n = 54), concentric hypertrophy (n = 16) or eccentric hypertrophy (n = 25). RESULTS: All groups were similar in age, gender distribution and body size. Patients with concentric and eccentric hypertrophy had similar blood pressures (mean 173/100 and 171/99 mm Hg, respectively) and left ventricular mass, but compared with patients with normal left ventricular geometry and concentric remodeling, only those with concentric hypertrophy had increased arterial wall thickness (0.96 +/- 0.20 vs. 0.80 +/- 0.18 mm, p < 0.05), end-diastolic diameter (6.38 +/- 0.97 vs. 5.76 +/- 0.87 mm, p < 0.05), cross-sectional area (22.1 +/- 5.71 vs. 16.6 +/- 5.4 mm(1)2 p < 0.05) and elastic modulus (713 +/- 265 vs. 471 +/- 241 dynes/cm2 x 10(-5), p < 0.05). Patients with concentric remodeling and eccentric hypertrophy had similar values for these measures (0.85 +/- 0.22 and 0.89 +/- 0.21 mm, 5.67 +/- 0.77 and 6.04 +/- 0.44 mm, 17.2 +/- 5.4 and 19.7 +/- 5.9 mm2, 558 +/- 263 and 614 +/- 257 dynes/cm2 x 10(-6), respectively), despite lower systolic blood pressures in the former group (156/94 mm Hg, p < 0.001). The prevalence of plaque was comparable in patients with concentric (56%) and eccentric (42%) hypertrophy and significantly greater than that in patients [corrected] with normal geometry (21%). CONCLUSIONS: Among patients with generally mild, uncomplicated systemic hypertension, arterial structure and function are most abnormal when concentric left ventricular hypertrophy is present and may contribute to the more adverse outcome associated with this geometric pattern.

Adaptation, Physiological↗
PubMed1996

Work-related stress and blood pressure: current theoretical models and considerations from a behavioral medicine perspective.

There is extensive evidence that the prevalence of human hypertension is related to psychosocial factors, possibly including chronic exposure to stress. A tripartite model, consistent with the literature on stress and health, may help to define this relationship better. Its 3 components are environmental stressors, individual factors affecting the perception of stress, and the individual's physiological susceptibility. To date, researchers have looked at individual parts of this model, but rarely at all 3. Some models of work stress (e.g., the job strain, effort-reward, and person-environment fit models) focus on work-related stressors alone or in conjunction with individual characteristics. Other models (e.g., the defense-defeat, John Henryism, and reactivity models) focus on individual differences in response, with little attention paid to the nature of the stressors. The authors suggest that it is timely to integrate these approaches and to look for physiological mechanisms.

Adaptation, Psychological↗
PubMed1996

White coat hypertension.

Several recent studies of white coat hypertension have confirmed that it occurs in 20% or more of the hypertensive population. White coat hypertension appears to be a low-risk condition because it is associated with little or no organ damage, and is not usually associated with the metabolic abnormalities characteristic of sustained hypertension, such as high plasma lipid levels. Thus the cutoff point used to define white coat hypertension is increasingly being used as a treatment threshold. An alternative approach for defining treatment thresholds has been the study of ambulatory blood pressure in normotensive populations, taking the 95th percentile as the upper limit of normal. This approach yields unacceptably high cutoff points. Studies of the white coat effect, defined as the difference between clinic and ambulatory pressure, have shown that it is more pronounced in patients with more severe hypertension, and that it does not correlate with target organ damage. Drug treatment of white coat hypertension often results in a reduction of clinic pressure more than of ambulatory pressure, but the white coat effect is still seen in treated patients. One recently published study indicates that the prognosis of white coat hypertensive patients in benign.

Antihypertensive Agents↗
PubMed1996

Effect of hypertension on aortic root size and prevalence of aortic regurgitation.

Although early reports suggested that hypertension predisposed to aortic root enlargement and consequent aortic regurgitation, more recent pathological and M-mode echocardiographic studies have not found an association between hypertension and aortic enlargement when age is considered. These discrepancies may partially reflect methodological shortcomings in the accuracy and reproducibility of aortic and blood pressure measurements. Therefore, we measured two-dimensional echocardiographic diameters of the aortic root at four locations and compared findings with ambulatory and resting blood pressures and measures of body size in 110 normotensive and 110 hypertensive men and women matched for age and sex. Aortic diameters at the anulus (2.41 +/- 0.29 versus 2.34 +/- 0.24 cm, P = .06) and sinuses (3.47 +/- 0.44 versus 3.37 +/- 0.36 cm, P = .08) were marginally higher, whereas diameters at the supra-aortic ridge (2.94 +/- 0-38 versus 2.81 +/- 0.32 cm, P < .01) and ascending aorta (3.26 +/- 0.45 versus 3.11 +/- 0.32 cm, P < .01) were significantly increased in hypertensive subjects. Aortic diameters increased with increasing quartiles of diastolic and systolic pressures, particularly at the supra-aortic ridge and ascending aorta. In multivariate analyses, blood pressure remained an independent determinant of distal aortic diameters after body size and age were considered. Aortic regurgitation was seen in 5 normotensive and 7 hypertensive subjects and did not differ in severity. Thus, hypertension is associated with a slight increase in aortic root size, most notably of the supra-aortic ridge and proximal ascending aorta. Although dilatation at the commissural attachment might be expected to predispose to an increase in aortic regurgitation, we did not detect such a difference in this population of healthy, asymptomatic individuals.

Adult↗
PubMed1996

Environmental influences on blood pressure and the role of job strain.

OBJECTIVE: To review the evidence that human essential hypertension is at least in part the result of the influence of psychosocial factors, with special reference to occupational stress (job strain). FINDINGS: The prevalence of human hypertension is related to social factors such as urbanization and education. Several studies, conducted both experimentally in animals and observationally in people, have suggested that chronic social conflict is associated with higher blood pressure. Ambulatory monitoring has shown that most people have their highest pressures during working hours. Occupational stress can be evaluated as job strain, which is a combination of high demands at work with low decision latitude or control. Job strain has been related to coronary heart disease, and a number of studies have shown that it is also associated with higher ambulatory blood pressures, both cross-sectionally and prospectively, in men but not in women. Men in high strain jobs also show an increased left ventricular mass. Laboratory studies of blood pressure reactivity to stressful tasks support the concept of loss of control being associated with higher pressures. CONCLUSIONS: Job strain is a risk factor for hypertension in men, but not in women.

Blood Pressure↗
PubMed1995

Association of carotid atherosclerosis and left ventricular hypertrophy.

OBJECTIVES: This study was undertaken to determine the prevalence of carotid atherosclerosis in a large group of asymptomatic hypertensive and normotensive adults and to examine its relation to the presence of left ventricular hypertrophy. BACKGROUND: Both electrocardiographic and echocardiographic left ventricular hypertrophy predict an increased risk of cardiovascular events and mortality, including cerebrovascular disease, but the mechanism of association is unknown. METHODS: Four hundred eighty-six (277 normotensive and 209 untreated hypertensive) adults, free of clinical evidence of cardiovascular disease, were studied prospectively with echocardiography to determine left ventricular mass and carotid ultrasound to detect atherosclerosis and to measure common carotid artery dimensions. RESULTS: Carotid atherosclerosis was present in 16% of normotensive and 23% of hypertensive participants (p < 0.05) and was associated with older age, higher systolic and pulse pressures and larger left ventricular mass index ([mean +/- SD] 91 +/- 19 vs. 82 +/- 18 g/m2, p < 0.0001). The difference in mass persisted after adjustment for baseline differences in age and blood pressure. Subjects with left ventricular hypertrophy were twice as likely to have carotid atheromas (35% vs. 18%, p < 0.01). Logistic regression analyses, including standard risk factors, indicated that only age and left ventricular mass index independently predicted the presence of carotid plaque, both in the entire study group and when normotensive and hypertensive subjects were considered separately. CONCLUSIONS: We believe that the present study provides the first evidence that higher left ventricular mass as detected by echocardiography is associated with the presence of carotid plaque. The association between cardiac hypertrophy and systemic atherosclerosis may contribute to the pathogenesis of the high incidence of vascular events that is well documented in patients with left ventricular hypertrophy.

Adult↗
PubMed1995

Association between delayed recovery of blood pressure after acute mental stress and parental history of hypertension.

OBJECTIVE: To assess the influence of sex, race and parental history of hypertension on blood pressure and heart rate elevations during a stressor, and on the recovery of prestress baseline levels for these parameters. DESIGN: Five hundred and thirty-seven university undergraduates underwent cardiovascular reactivity testing. A serial-subtraction task served as the stressor. Reactivity was assessed as the difference between baseline and during-task levels, and recovery as the difference between baseline and post-stress levels. METHODS: The influence of sex, race and parental history of hypertension on reactivity and recovery was assessed, using analysis of variance models. RESULTS: No differences were found in reactivity for any of the factors. For recovery, a significant effect was found for parental history of hypertension on systolic blood pressure and a marginal effect on diastolic blood pressure. Post hoc tests revealed that values in groups with two hypertensive parents remained elevated at a significantly higher level than in offspring with either no or one hypertensive parent. CONCLUSION: Parental history of hypertension may affect the duration of the blood pressure response to an acute stressor more than the magnitude of the response.

Acute Disease↗
PubMed1995

Relationship of effective arterial elastance to demographic and arterial characteristics in normotensive and hypertensive adults.

OBJECTIVE: To evaluate demographic and vascular correlates of the effective arterial elastance noninvasively in normotensive and hypertensive adults. METHODS: In 202 subjects carotid ultrasonography and external arterial tonometry were simultaneously performed; carotid cross-sectional area, absolute and relative wall thicknesses, Peterson's and Young's elastic moduli and beta', a pressure-dependent index of arterial stiffness, were calculated. The impact of reflected waves on central pressure waveforms was evaluated by the 'augmentation index' (the relative increment in systolic pressure caused by the late-systolic peak). Left ventricular mass and relative wall thickness were assessed echocardiographically. The effective arterial elastance was estimated by dividing the pressure at the dicrotic notch by the Doppler-determined stroke index. RESULTS: The effective arterial elastance was higher in women among normotensives but similar between sexes among hypertensive subjects. It was correlated to age, mean blood pressure, body mass index and measures of arterial function, including Peterson's and Young's elastic moduli and beta', and to the augmentation index. It was also related to absolute and relative carotid wall thicknesses, lumen diameter and indexed cross-sectional area. Age, beta' and carotid cross-sectional area independently predicted effective arterial elastance in multiple regression analysis. CONCLUSIONS: Effective arterial elastance is related to demographic and arterial structural and functional characteristics. Increases in effective arterial elastance resulting from altered arterial structure and function may play a role in inducing left ventricular adaptative modifications.

Adult↗
PubMed1995

Ambulatory blood pressure monitoring for evaluating the relationships between lifestyle, hypertension and cardiovascular risk.

1. Ambulatory monitoring provides a unique opportunity for studying the temporal relationships between lifestyle factors and blood pressure (BP). These include physical activity, mental activity, environmental stressors, substances ingested for pleasure such as smoking, alcohol and caffeine, and nutrition. 2. Changes in physical activity play a major role in determining the diurnal profile of BP, whereas the influence of mood is small. 3. Environmental stress, in the form of job strain, has been shown to be associated with a sustained increase of BP throughout the day and night in men, and also with an increased left ventricular mass. The effects are most marked in men who drink alcohol regularly. Job strain does not appear to influence BP in women. 4. Although it is recognized that smoking raises BP acutely, its long-term effects have been unclear. Ambulatory monitoring shows that smokers have a larger diurnal swing of BP than non-smokers, because of a higher daytime pressure. Alcohol also increases the diurnal swing of BP. 5. Ambulatory monitoring has been used relatively little for evaluating nutritional factors, but has the possibility of quantifying their effects on BP more reliably than traditional methods, and also elucidating the underlying mechanisms.

Blood Pressure Monitoring, Ambulatory↗
PubMed1995

Prevalence and determinants of cardiac and vascular hypertrophy in hypertension.

Hypertrophy of the capacitance arteries has recently been documented in hypertensive patients by noninvasive ultrasound techniques. To better define the prevalence and determinants of vascular hypertrophy and its potential association with ventricular hypertrophy in hypertension, we compared carotid and cardiac ultrasound findings in 172 normotensive and 172 unmedicated hypertensive subjects matched for age and sex. Despite similar body size, hypertension was associated with increased left ventricular wall thicknesses, mass, and mass index (89 versus 80 g/m2, P < .0001 for all comparisons) and increased carotid wall thickness (0.82 versus 0.77 mm) and cross-section area (17.1 versus 15.3 mm2, P < .005 for both comparisons). Among the 172 normotensive subjects, left ventricular hypertrophy was noted in 9 (5.2%) and arterial hypertrophy was found in 9 (5.2%), whereas ventricular hypertrophy was found in 21 (12.2%) and arterial hypertrophy in 19 (11%) hypertensive subjects. Arterial hypertrophy was found in 9% of hypertensive subjects with normal ventricular mass and in 24% with left ventricular hypertrophy (P < .05). Among hypertensive subjects carotid wall thickness and cross-sectional area were most strongly related to age and systolic pressure (P < .0001 for all comparisons), with little contribution form body size. Carotid relative wall thickness was only related to increasing age (P < .01). In contrast, left ventricular wall thickness and mass were strongly related to body size and systolic pressure (P < .0001 for comparisons) but not to age (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Isolated elevation of diastolic blood pressure. Real or artifactual?

Not infrequently, blood pressure measurement by the standard auscultatory technique yields a normal systolic pressure with an elevated diastolic pressure. The relatively narrow pulse pressure of such a measurement raises concern about the accuracy of the blood pressure measurement. The purpose of this study was to assess the accuracy of auscultatory blood pressure measurements in patients with an uncommonly narrow pulse pressure, particularly patients with an elevated diastolic but normal systolic pressure. Auscultatory blood pressure measurements were compared with an objective noninvasive standard, called K2 analysis, which has been shown to be more accurate than the auscultatory technique. Blood pressure was measured simultaneously by auscultatory and K2 techniques in 175 subjects. Comparisons were performed (1) in the group as a whole, (2) in four clinical subgroups (normotensive [< 140/< 90 mm Hg, n = 69], hypertensive [> or = 140/> or = 90 mm Hg, n = 53], isolated systolic hypertensive [> or = 140/< 90 mm Hg, n = 38], and isolated diastolic hypertensive [< 140/> or = 90 mm Hg, n = 15]), and (3) in two subgroups whose ratio of pulse pressure to diastolic pressure was greater than or equal to 0.45 (n = 151) or less than 0.45 (n = 24). Subjects in the isolated diastolic hypertensive group and in the group with a pulse pressure ratio less than 0.45 were considered to have a narrow pulse pressure. In the group as a whole, consistent with previous auscultatory-K2 comparisons, systolic pressure was slightly higher and diastolic pressure slightly lower when measured by K2 versus the auscultatory technique (auscultatory, 145/85 mm Hg; K2, 147/83 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Is white coat hypertension associated with arterial disease or left ventricular hypertrophy?

Although white coat hypertension may be present in 20% or more of hypertensive individuals, its prognostic significance is unknown. We compared prognostically relevant measures of target-organ damage among 24 individuals with white coat hypertension and age- and sex-matched groups of sustained hypertensive and normotensive subjects classified by clinical and 24-hour ambulatory blood pressures. Left ventricular and carotid artery structure and function were evaluated by ultrasonography. Left ventricular mass index was similar in white coat hypertensive (82 +/- 17 g/m2) and normotensive (78 +/- 15 g/m2) subjects but was higher in sustained hypertensive subjects (97 +/- 19 g/m2, P < .02 and P < .002, respectively). Similarly, carotid artery intimal-medial thickness was greater in the sustained hypertensive group (0.98 +/- 0.21 mm) than in the white coat hypertensive (0.84 +/- 0.16 mm, P < .05) and normotensive (0.76 +/- 0.18 mm, P < .001) groups. The prevalence of discrete atherosclerotic plaques was higher in the sustained hypertensive group (58%) than in the white coat hypertensive (25%, P < .05) and normotensive (21%, P < .02) groups. Cardiac and carotid structure in individuals with white coat hypertension resemble findings in normotensive subjects and differ significantly from those in age- and sex-matched sustained hypertensive subjects. These findings suggest that white coat hypertension may be a benign condition for which pharmacological intervention may not be necessary, a hypothesis that needs to be tested in longitudinal studies with clinical end points.

Adult↗
PubMed1995

Utility of 24 h ambulatory blood pressure monitoring in clinical practice.

The technique of noninvasive ambulatory blood pressure monitoring was first described more than 30 years ago, but is only now becoming accepted as a clinically useful procedure for the evaluation of patients with abnormal blood pressure regulation. This applies mostly to those with known or suspected high blood pressure, but also includes the less common situation of low blood pressure. In addition to providing a better estimate of the average or true blood pressure, ambulatory monitoring may reveal changes in the variations in blood pressure over 24 h that would not be detected by more conventional measurement techniques. The two most important aspects are alterations in the pattern of the diurnal rhythm of blood pressure and short term blood pressure variability.

Blood Pressure Monitoring, Ambulatory↗
PubMed1995

Factors influencing the awake-sleep difference in ambulatory blood pressure: main effects and sex differences.

The purpose of this study was to assess the biological and behavioural characteristics associated with the variation in the awake-sleep blood pressure (BP) difference in a large series of patients who had ambulatory BP monitoring. The 1186 subjects in the study (689 men and 497 women) each wore an ambulatory BP monitor over one 24 h period. All patients had been off antihypertensive medication for at least 3 weeks prior to the BP monitoring. The extent of the difference in awake-sleep BP was defined by the percentage change to sleep pressure from the average awake value. The results showed that when the average levels of office, awake and sleep pressures are compared across groups defined by this percentage change, there is no statistically significant association between the level of office pressure and the extent of the awake-sleep pressure difference. In accordance with this finding, the relation between ambulatory awake BP and the awake-sleep difference was relatively weak, although significant (P < 0.01). In striking contrast, the ambulatory sleep pressure was a very strong predictor of the awake-sleep difference (P < 0.0001), such that subjects with the lowest sleep pressures had the biggest diurnal change. In examining the factors associated with the awake-sleep change in pressure, the most important predictors were a low sleep pressure and alcohol intake, both of which were associated with bigger diurnal changes of both SBP and DBP in both men and women. A large pulse pressure while awake (that is, isolated systolic hypertension) was also associated with bigger diurnal changes in both sexes. The only other predictive factor which applied in both sexes was a low awake BP variability which was associated with a greater diurnal variation of DBP. Among men but not women, older age, smoking cigarettes, and being overweight were associated with bigger diurnal changes of both SBP and DBP, and a family history of hypertension was also associated with a bigger diurnal change of systolic pressure. Finally, among women but not men, being measured in winter months was associated with a greater awake-sleep difference in diastolic pressure. These results show that there is a general pattern of factors which predict awake-sleep changes in men and women, but there are also contributing behavioural factors which are sex specific. As awake-sleep changes of BP may be of prognostic significance, behavioural factors need to be considered when evaluating this change.

Alcohol Drinking↗