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Biomedical subjects

T G Pickering

Publications and source records attributed to T G Pickering.

At least 19 recordsLinked to original sources
PubMed1992

Detection of renovascular hypertension. State of the art: 1992.

PURPOSE: To review recent advances in detecting renovascular hypertension. DATA SOURCES: Original English-language reports obtained through a MEDLINE search for the years 1987 to 1991. Also, a manual search through Index Medicus as well as bibliographies of original reports and selected review articles. STUDY SELECTION AND DATA EXTRACTION: Cited studies were critically reviewed with emphasis on study size, patient sample, methods, diagnostic criteria, and reproducibility of results. Where applicable, reviews that combined the results of smaller studies are cited. RESULTS: A sensitivity of 74% and a specificity of 89% have been reported for the captopril test and of 93% and 95%, respectively, for captopril scintigraphy with diethylenetriaminepentaacetic acid (DTPA). The sensitivity and specificity of renal vein renin determination are 80% and 62%, respectively and may increase with the use of stricter technical criteria and maneuvers to stimulate renin secretion. These tests differentiate renovascular hypertension from essential hypertension more reliably than from asymmetric renal parenchymal disease; however, they do not reliably distinguish unilateral from bilateral stenosis. Other tests are less widely used. Intravenous pyelography (sensitivity, 74.5%; specificity, 86.2%) has the disadvantages of radiation and dye load exposure. Intravenous angiography is expensive and invasive and does not always enable visualization of the origin of the renal artery. The roles of duplex ultrasound and magnetic resonance angiography remain to be clarified. CONCLUSIONS: Noninvasive tests are cost effective and have a high predictive value in patients with clinical clues suggestive of renovascular hypertension. These tests are not recommended for use in patients with a low likelihood of disease.

Decision Trees↗
PubMed1992

The impact of anticipation of job loss on psychological distress and worksite blood pressure.

The impact of occupational stressful life events on psychological distress and blood pressure was examined among employees of a major New York City brokerage firm undergoing massive layoffs. One hundred thirty-nine employees of the firm, who had participated in a blood pressure screening in 1986, were rescreened during the period of layoffs within their company in 1989. About two-thirds of the 139 employees reported being "somewhat" or "very" anxious or upset in 1989 during the period of layoffs, and psychological distress was significantly elevated among those employees reporting possible or definite layoff or job change and/or difficulty in obtaining a comparable job. However, we found no increase in overall blood pressure level, and no effect of anticipation of job loss on 1989 blood pressure when controlling for 1986 blood pressure level, age, body mass index, work hours, and other demographic variables. On the other hand, employment in a department sold to another employer on the day of screening, as well as employment in a clerical job title, were both associated with significant increases in diastolic blood pressure of about 5 mm Hg.

Anxiety↗
PubMed1992

Patterns of left ventricular hypertrophy and geometric remodeling in essential hypertension.

The spectrum of left ventricular geometric adaptation to hypertension was investigated in 165 patients with untreated essential hypertension and 125 age- and gender-matched normal adults studied by two-dimensional and M-mode echocardiography. Among hypertensive patients, left ventricular mass index and relative wall thickness were normal in 52%, whereas 13% had increased relative wall thickness with normal ventricular mass ("concentric remodeling"), 27% had increased mass with normal relative wall thickness (eccentric hypertrophy) and only 8% had "typical" hypertensive concentric hypertrophy (increase in both variables). Systemic hemodynamics paralleled ventricular geometry, with the highest peripheral resistance in the groups with concentric remodeling and hypertrophy, whereas cardiac index was super-normal in those with eccentric hypertrophy and low normal in patients with concentric remodeling. The left ventricular short-axis/long-axis ratio was positively related to stroke volume (r = 0.45, p less than 0.001), with cavity shape most elliptic in patients with concentric remodeling and most spheric in those with eccentric hypertrophy. Normality of left ventricular mass in concentric remodeling appeared to reflect offsetting by volume "underload" of the effects of pressure overload, whereas eccentric hypertrophy was associated with concomitant pressure and volume overload. Thus, arterial hypertension is associated with a spectrum of cardiac geometric adaptation matched to systemic hemodynamics and ventricular load. Concentric left ventricular remodeling and eccentric hypertrophy are more common than the typical pattern of concentric hypertrophy in untreated hypertensive patients.

Adaptation, Physiological↗
PubMed1992

Parallel cardiac and vascular adaptation in hypertension.

BACKGROUND: Although vascular damage in the noncoronary circulation is a major cause of complications in hypertension, relatively little is known of the in vivo geometry and function of the arterial circulation in patients with uncomplicated hypertension or of their relation to left ventricular hypertrophy, a marker of enhanced risk of cardiovascular complications. METHODS AND RESULTS: Wall thickness and internal diameter of the common carotid artery and the presence of atherosclerosis within the extracranial carotid arteries were determined by ultrasound in 43 asymptomatic hypertensive patients and 43 normotensive subjects matched for sex, age, and body size. Vascular stiffness was estimated from simultaneous superimposed carotid pressure waveforms obtained with an external solid-state transducer. Left ventricular size and function were determined echocardiographically. Compared with normal subjects, hypertensive patients had greater left ventricular absolute and relative wall thicknesses, left ventricular mass, and carotid absolute and relative wall thicknesses (p < 0.005). Carotid intimal-medial thickness exceeded the 95th percentile of normal values in 28% of hypertensive patients (p < 0.01). Carotid atherosclerosis was equally prevalent within the two blood pressure groups and was associated with older age, larger left ventricular and carotid wall thicknesses, and carotid diameter. Despite similar carotid pulse pressures, vascular stiffness was significantly increased in the hypertensive patients. Among the population as a whole, significant relations existed between cardiac and vascular wall thicknesses and internal dimensions. In multivariate analyses, these relations were statistically independent of age and blood pressure. CONCLUSIONS: The present study documents the presence of geometric and functional changes within the common carotid artery in uncomplicated hypertension that parallel findings within the left ventricle. The potential contribution of these changes to the cardiovascular complications of hypertension, particularly in the setting of left ventricular hypertrophy, is unknown.

Adaptation, Physiological↗
PubMed1992

Relation between job strain, alcohol, and ambulatory blood pressure.

"Job strain" (defined as high psychological demands and low decision latitude on the job) has been previously reported to be associated with increased risk of hypertension and increased left ventricular mass index (LVMI) in a case-control study of healthy employed men, aged 30-60 years, without evidence of coronary heart disease. We hypothesized that job strain would be associated with increased ambulatory blood pressure (AmBP). A total of 264 men at eight work sites wore an AmBP monitor for 24 hours on a working day. In an analysis of covariance model, job strain was associated with an increase in systolic AmBP of 6.8 mm Hg (p = 0.002) and diastolic AmBP of 2.8 mm Hg at work (p = 0.03) after adjusting for age, race, body mass index, Type A behavior, alcohol behavior, smoking, work site, 24-hour urine sodium, education, and physical demand level of the job. Alcohol use also had a significant effect on AmBP. However, among subjects not in high-strain jobs, alcohol had no apparent effect on AmBP at work. Instead, alcohol use and job strain interacted such that workers in high-strain jobs who drank regularly had significantly higher systolic AmBP at work (p = 0.007). Among the other risk factors, only age, body mass index, and smoking had significant effects on AmBP. Job strain also had significant effects on AmBP at home and during sleep as well as on LVMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Cortisol inactivation overload: a mechanism of mineralocorticoid hypertension in the ectopic adrenocorticotropin syndrome.

The more severe mineralocorticoid manifestations in the ectopic ACTH syndrome compared to pituitary Cushing's disease have been attributed to hypersecretion of 11-deoxycorticosterone. Another difference between the two forms of ACTH-excess, however, is a more severe degree of hypercortisolism in the ectopic syndrome. Cortisol can become a potent mineralocorticoid if its peripheral metabolism is interfered with as occurs in the syndrome of apparent mineralocorticoid excess. This mechanism also occurs in an experimental model of the apparent mineralocorticoid excess syndrome induced by licorice derivatives. We have tested the hypothesis that cortisol is a major mineralocorticoid in the ectopic ACTH syndrome because of two factors, marked hypersecretion and incomplete peripheral metabolism of cortisol as a result of an overload of metabolizing enzymes. Two measures of the peripheral metabolism of cortisol were found to be markedly decreased in two patients with the ectopic ACTH syndrome. The cortisol turnover quotients were 17.2 and 19.6 (normal = 215 +/- 98) and the ring A reduction constants were 11.8 and 13.8 (normal = 101 +/- 23). These values were comparable to that found in the syndrome of apparent mineralocorticoid excess and consistent with the hypothesis that cortisol is a significant functioning mineralocorticoid in the ectopic ACTH syndrome.

ACTH Syndrome, Ectopic↗
PubMed1992

Non-invasive measurements of arterial compliance in hypertensive compared with normotensive adults.

AIM: To determine differences in arterial compliance attributable to hypertension. METHODS: Since measurements of arterial compliance have tended to vary in the past according to the method used, a new technique comprising carotid ultrasound and simultaneous, calibrated, carotid pressure waveform measurements was tested in 43 hypertensives and 43 control subjects matched for age, gender and body size. RESULTS: There was a significant reduction in compliance among the hypertensive patients, as estimated by the elastic modulus and the ratio of stroke volume to pulse pressure. However, when the non-linearity of the pressure-volume relationship and the impact of distending pressure were taken into account, by the arterial stiffness index and by the increase in arterial wall thickness associated with hypertension by Young's modulus, there were no significant differences in arterial compliance between the two groups.

Adult↗
PubMed1991

Elevation of ambulatory systolic blood pressure in hypertensive smokers. A case-control study.

Although smoking raises blood pressure, the office blood pressure measurements of smokers are the same as, or lower than, those of nonsmokers. To resolve this paradox, we compared the office and 24-hour ambulatory blood pressures of 59 untreated hypertensive smokers with 118 nonsmoking hypertensives matched for age, sex, and race. The office blood pressures of the smoking and nonsmoking groups were 141/93 and 142/93 mm Hg, respectively. The awake ambulatory systolic blood pressure was significantly higher in the smokers (145 vs 140 mm Hg). This difference was greater among patients over the age of 50 years (153 vs 142 mmHg), and absent among patients under 50 years (140 vs 139 mm Hg). Blood pressures during sleep did not differ between the two groups (121/76 vs 123/77 mm Hg). We conclude that, among white hypertensives above the age of 50 years, smokers maintain a higher daytime ambulatory systolic blood pressure than nonsmokers even though blood pressure measured in the office is similar.

Adult↗
PubMed1991

Ambulatory blood pressure monitoring: assessing the diurnal variation of blood pressure.

The purposes of this paper are to examine the effects of activity, situation of measurement, mood, and occupation on the daily variation of blood pressure and to discuss the potential utility of ambulatory blood pressure monitoring in physical anthropological studies. The subjects of the blood pressure variability study are 125 men who were referred to the Hypertension Center at New York Hospital--Cornell Medical Center for evaluation of hypertension. There were 1,386 blood pressure measurements from these subjects available for study, which were taken using noninvasive ambulatory blood pressure monitoring techniques. Pressures were transformed to z scores using the subject's daily mean pressure and standard deviation to assess the relative elevation during the experience of the various factors. The results show that activity and mood are the most significant sources of blood pressure variation (P less than .005) and are additive. Occupation, which may be an indicator of social class in this population, also modified the mood effects. Because ambulatory blood pressure monitors obtain many readings over a day under a variety of circumstances, their use can improve epidemiological and human biological studies of the inheritance and variability of blood pressure. Ambulatory blood pressure monitoring is an important new tool in the study of human biological variation.

Affect↗
PubMed1991

Captopril renography in the diagnosis of renal artery stenosis: accuracy and limitations.

PURPOSE: The purpose of this study was to determine the sensitivity, specificity, and clinical usefulness of renography performed in combination with captopril administration ("captopril renography") in diagnosing renal artery stenosis. PATIENTS AND METHODS: Fifty-five patients with suspected renal artery stenosis underwent renography prior to performance of renal angiography. Renography was performed on two consecutive days using technetium-99m-diethylenetiamine pentaacetic acid (DTPA) as an index of glomerular filtration rate and iodine-131-orthoiodohippurate (OIH) as an index of renal blood flow. Captopril (25 mg orally, crushed) was administered 1 hour before the second study. Renal artery stenosis was defined as a stenosis exceeding 70%. Renographic criteria were then established, retrospectively, to differentiate renal artery stenosis from essential hypertension based on (1) asymmetry of function and (2) the presence of captopril-induced changes. RESULTS: Renal artery stenosis was detected in 35 of 55 patients (21 with unilateral and 14 with bilateral stenosis). Three criteria were established for diagnosing renal artery stenosis: (1) a percent uptake of DTPA by the affected kidney of less than 40% of the combined bilateral uptake, (2) a delayed time to peak uptake of DTPA, which was more than 5 minutes longer in the affected kidney than in the contralateral kidney, (3) a delayed excretion of DTPA, with retention at 15 minutes, as a fraction of peak activity, more than 20% greater than in the contralateral kidney. The presence of one or more of these criteria was diagnostic of renal artery stenosis, with a sensitivity and specificity of 71% and 75%, respectively before captopril administration, and 94% and 95% after captopril administration. Lesser degrees of asymmetry (i.e., uptake of 40% to 50%) had very poor diagnostic specificity. Among patients with bilateral stenoses, asymmetry identified the more severely affected kidney, but the presence or absence of stenosis in the contralateral kidney could not be reliably determined. When pre- and post-captopril studies were compared, the presence of captopril-induced scintigraphic changes was a highly specific finding for renal artery stenosis, but occurred in only 51% of the cases. OIH scintigraphy provided similar results, with slightly lower sensitivity and specificity. CONCLUSION: Asymmetry of DTPA uptake, time to peak uptake, or retention seen on a single post-captopril renogram is a highly sensitive and specific finding in detecting renal artery stenosis but does not distinguish unilateral from bilateral disease. If renograms are obtained both before and after captopril administration, the presence of captopril-induced change is a highly specific finding for the detection of renal artery stenosis, but the sensitivity of this finding is low.

Antihypertensive Agents↗
PubMed1991

The use of angiotensin converting enzyme inhibitors in combination with other antihypertensive agents.

Angiotensin converting enzyme (ACE) inhibitors have additive effects with most other antihypertensive agents, but the mechanisms of these interactions vary. With diuretics the interaction with ACE inhibitors can be explained by their contrasting effects on the renin-angiotensin system, while with calcium antagonists it may be attributed to independent mechanisms of action. With beta-blockers there is a variable additive effect, which has been proposed to be due to more complete blockade of the renin-angiotensin system than can be obtained with either type of agent alone.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

A multicenter evaluation of the A&D TM-2420 ambulatory blood pressure recorder.

The A&D TM-2420 (A&D Engineering, Milpitas, CA) is an automatic, portable, noninvasive blood pressure (BP) recorder which uses a dual microphone system for the detection of Korotkoff sounds. Its accuracy and clinical performance were assessed in a multicenter study that also addressed issues such as observer agreement and the effects of age, arm circumference, heart rate, posture, and blood pressure level on the observer-device differences. We compared 906 simultaneous, same-arm BP measurements in 151 subjects using the TM-2420 versus two skilled clinicians per site using a teaching stethoscope. The agreement between the TM-2420 and mercury column determinations were within 10 mm Hg for 86 to 91% of systolic readings and 91 to 94% of diastolic readings, depending on the posture; a level of agreement which would receive a 'B+' grade from the recent British Hypertension Society guidelines. The limits of agreement (2 standard deviations about the mean difference) for systolic BP between observers and the TM-2420 tended to be greater for the standing position (-20 to 15 mm Hg) compared to supine (-14 to 12 mm Hg) and seated (-13 to 8 mm Hg) positions. Limits of agreement between the observers and device were not dependent upon age, heart rate, arm size, or blood pressure level. Twenty-four-hour blood pressure monitoring in two of the four centers demonstrated an error code rate of 3.4%, excluding 'retries' that are one of the device's features. These data demonstrate an acceptable level of accuracy and performance of the sixth generation of the TM-2420 for use in clinical practice and research.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Challenge response predictors. General principles.

Environmental challenges offer a potential method for predicting hypertension. They could be nutritional (eg, an increased salt load), behavioral (eg, a mental arithmetic task), or physical (eg, an exercise test) in nature. An ideal challenge test should be simple to administer, easily standardized, and with a response that can be precisely quantified. The response is best expressed as a change score from the baseline level, and should be reproducible over time. For the prediction of hypertension, blood pressure is the usual response measure, although others, such as heart rate, are possible. The response should have predictive value independently of other known predictors, including the baseline level. The dependent variables might be future blood pressure, target organ damage, or morbid events.

Behavior↗