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Biomedical subjects

T G Pickering

Publications and source records attributed to T G Pickering.

At least 37 records · Page 2Linked to original sources
PubMed2001

Stroke prognosis and abnormal nocturnal blood pressure falls in older hypertensives.

It remains uncertain whether abnormal dipping patterns of nocturnal blood pressure influence the prognosis for stroke. We studied stroke events in 575 older Japanese patients with sustained hypertension determined by ambulatory blood pressure monitoring (without medication). They were subclassified by their nocturnal systolic blood pressure fall (97 extreme-dippers, with >/=20% nocturnal systolic blood pressure fall; 230 dippers, with >/=10% but <20% fall; 185 nondippers, with >/=0% but <10% fall; and 63 reverse-dippers, with <0% fall) and were followed prospectively for an average duration of 41 months. Baseline brain magnetic resonance imaging (MRI) disclosed that the percentages with multiple silent cerebral infarct were 53% in extreme-dippers, 29% in dippers, 41% in nondippers, and 49% in reverse-dippers. There was a J-shaped relationship between dipping status and stroke incidence (extreme-dippers, 12%; dippers, 6.1%; nondippers, 7.6%; and reverse-dippers, 22%), and this remained significant in a Cox regression analysis after controlling for age, gender, body mass index, 24-hour systolic blood pressure, and antihypertensive medication. Intracranial hemorrhage was more common in reverse-dippers (29% of strokes) than in other subgroups (7.7% of strokes, P=0.04). In the extreme-dipper group, 27% of strokes were ischemic strokes that occurred during sleep (versus 8.6% of strokes in the other 3 subgroups, P=0.11). In conclusion, in older Japanese hypertensive patients, extreme dipping of nocturnal blood pressure may be related to silent and clinical cerebral ischemia through hypoperfusion during sleep or an exaggerated morning rise of blood pressure, whereas reverse dipping may pose a risk for intracranial hemorrhage.

Aged↗
PubMed2001

Gender differences in associations of diurnal blood pressure variation, awake physical activity, and sleep quality with negative affect: the work site blood pressure study.

This study reports on the associations among depression, anxiety, awake physical activity, sleep quality (assessed by nocturnal physical activity), and diurnal blood pressure (BP) variation in a nonpsychiatric sample (The Work Site Blood Pressure Study). We conducted ambulatory BP (ABP) monitoring and actigraphy in 231 working men and women. Depression and anxiety were measured by the Brief Symptom Inventory. There were gender-specific associations between depression or anxiety and ABP parameters. In men, depression was associated positively with the sleep/awake systolic BP (SBP) ratio (r=0.24, P=0.006). After controlling for age, body mass index, and awake and sleep activity, depression remained significantly associated with the sleep/awake SBP ratio (r=0.25, P=0.005) and was also significantly related to sleep SBP (r=0.21, P=0.02). Anxiety, which was related to depression (r=0.73, P<0.0001), had a similar but slightly weaker pattern of associations with ABP and activity. These associations were not found in women, but there were associations of anxiety with awake SBP (r=0.24, P=0.01) and pulse rate (r=0.27, P=0.006). In conclusion, depression is associated with disrupted diurnal BP variation independent of ambulatory physical activity in working men, whereas anxiety is associated with awake SBP and pulse rate in women.

Adult↗
PubMed2000

Pheochromocytoma of the heart.

This is a presentation of a unique case of cardiac pheochromocytoma during pregnancy. The case is significant because pheochromocytoma is a difficult diagnosis and its rarity during pregnancy may lead to this important diagnosis being overlooked, even though treatment is specific and highly successful.

Adult↗
PubMed2000

Home blood pressure monitoring.

Hypertension is estimated to affect 43 to 56 million adults or 24% to 31% of the US population and is emerging as a major health problem in some countries in the Third World. Hypertension contributes to all the major atherosclerotic cardiovascular disease outcomes.

Blood Pressure Monitoring, Ambulatory↗
PubMed2000

Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study.

CONTEXT: Sleep-disordered breathing (SDB) and sleep apnea have been linked to hypertension in previous studies, but most of these studies used surrogate information to define SDB (eg, snoring) and were based on small clinic populations, or both. OBJECTIVE: To assess the association between SDB and hypertension in a large cohort of middle-aged and older persons. DESIGN AND SETTING: Cross-sectional analyses of participants in the Sleep Heart Health Study, a community-based multicenter study conducted between November 1995 and January 1998. PARTICIPANTS: A total of 6132 subjects recruited from ongoing population-based studies (aged > or = 40 years; 52.8% female). MAIN OUTCOME MEASURES: Apnea-hypopnea index (AHI, the average number of apneas plus hypopneas per hour of sleep, with apnea defined as a cessation of airflow and hypopnea defined as a > or = 30% reduction in airflow or thoracoabdominal excursion both of which are accompanied by a > or = 4% drop in oxyhemoglobin saturation) [corrected], obtained by unattended home polysomnography. Other measures include arousal index; percentage of sleep time below 90% oxygen saturation; history of snoring; and presence of hypertension, defined as resting blood pressure of at least 140/90 mm Hg or use of antihypertensive medication. RESULTS: Mean systolic and diastolic blood pressure and prevalence of hypertension increased significantly with increasing SDB measures, although some of this association was explained by body mass index (BMI). After adjusting for demographics and anthropometric variables (including BMI, neck circumference, and waist-to-hip ratio), as well as for alcohol intake and smoking, the odds ratio for hypertension, comparing the highest category of AHI (> or = 30 per hour) with the lowest category (< 1.5 per hour), was 1.37 (95% confidence interval [CI], 1.03-1.83; P for trend = .005). The corresponding estimate comparing the highest and lowest categories of percentage of sleep time below 90% oxygen saturation (> or = 12% vs < 0.05%) was 1.46 (95% CI, 1.12-1.88; P for trend <.001). In stratified analyses, associations of hypertension with either measure of SDB were seen in both sexes, older and younger ages, all ethnic groups, and among normal-weight and overweight individuals. Weaker and nonsignificant associations were observed for the arousal index or self-reported history of habitual snoring. CONCLUSION: Our findings from the largest cross-sectional study to date indicate that SDB is associated with systemic hypertension in middle-aged and older individuals of different sexes and ethnic backgrounds.

Adult↗
PubMed2000

Ambulatory blood pressure monitoring.

Ambulatory blood pressure monitoring (ABPM) is becoming widely accepted as a clinically useful tool for assessing cardiovascular risk in hypertensive patients, although it is not generally recognized for reimbursement in the United States. There are now six major prospective studies, all of which have shown that ABPM gives a better prediction of risk than conventional clinic measurement. A corollary of these findings is that patients with white coat hypertension have been found to be at relatively low risk. The major clinical indications include patients with newly diagnosed hypertension, suspected white coat hypertension, and refractory hypertension. White coat hypertension is common during pregnancy and may lead to unnecessary cesarean sections.

Blood Pressure↗
PubMed2000

Modification of high blood pressure after myocardial infarction.

The treatment of high blood pressure (BP) after myocardial infarction is extremely important to decrease reinfarction and mortality. BP should be controlled more strictly in this high-risk hypertensive population. Recently, many clinical trials have demonstrated the benefits of lifestyle modification and antihypertensive agents, particularly beta-blockers and angiotensin-converting-enzyme inhibitors for the treatment of acute myocardial infarction. Treatment with these agents that modify BP may benefit even normotensive patients after a myocardial infarction, although the benefit is greater in hypertensives.

Antihypertensive Agents↗
PubMed2000

Changes of nocturnal blood pressure dipping status in hypertensives by nighttime dosing of alpha-adrenergic blocker, doxazosin : results from the HALT study.

Abnormal nocturnal blood pressure (BP) dipping status may be partly determined by nocturnal sympathetic activity. We studied the effect of nighttime dosing of an alpha(1)-adrenergic blocker, doxazosin, on the BP dipping status of 118 hypertensives, all of whom underwent 24-hour ambulatory BP monitoring before and after treatment. The mean nighttime/daytime ratio of systolic BP was increased (0.91 after therapy versus 0.89 at baseline, P<0.05). The patients were initially divided into 4 groups on the basis of their dipping status at the baseline assessment: 18 (15%) were extreme dippers, with a nighttime systolic BP fall of at least 20% of daytime BP; 46 (39%) were dippers (fall between 10% and 20%); 48 (41%) were nondippers (fall between 0% and 10%); and 6 (5%) were risers (nocturnal increase of systolic BP). A shift in dipping status toward less nocturnal BP dipping was observed after doxazosin therapy (P<0.05). Dipping status was determined by nighttime more than by daytime BP, and this was not explained by differences in the number of daytime and nighttime readings. The effects of doxazosin on the mean nocturnal systolic BP changes were an increase of 4.3 mm Hg in extreme dippers and decreases of 0.7 mm Hg in dippers, 12 mm Hg in nondippers, and 18 mm Hg in risers; the reduction was only significant in the latter 2 groups (both P<0.01). To estimate the effects of regression to the mean on the changes in dipping status, we also defined dipping status with the average of the BPs before and after doxazosin and found no difference in the degree of nighttime BP reduction among each group. The reduction of daytime BP was now significantly greater in the subgroups with less dipping: 6. 4 mm Hg for extreme dippers and 16 mm Hg for risers (P<0.05). In conclusion, nighttime dosing with doxazosin markedly affects the nocturnal BP dipping status of hypertensives, but the apparently greater reduction in nighttime pressure in nondippers and risers may be, at least partly, due to the effect of regression to the mean. The most important determinants of the effect of doxazosin were the absolute BP levels, both day and night, rather than dipping status per se.

Adrenergic alpha-Antagonists↗
PubMed2000

Impact of arterial stiffening on left ventricular structure.

Aging of the vasculature results in arterial stiffening and an increase in systolic and pulse pressures. Although pressure load is a stimulus for left ventricular hypertrophy, the extent to which vascular stiffening per se, independent of blood pressure, influences left ventricular structure is uncertain. Two hundred seventy-six subjects (79 normotensive and 197 otherwise healthy hypertensive individuals) underwent echocardiography to assess left ventricular structure. Arterial stiffness was estimated by the pressure-independent stiffness index, beta, and the pressure-dependent elastic modulus derived from simultaneous carotid ultrasound and applanation tonometry. Systemic arterial compliance (the inverse of stiffness) was estimated by the arterial compliance index. In multivariate analysis, beta was related to age (P<0.001) and smoking history (P<0.01) but not mean pressure, whereas elastic modulus was related to age and mean pressure (both P<0.001). The arterial compliance index was only related to age. Whereas systolic and diastolic pressures and the elastic modulus were positively associated with left ventricular mass (all P<0.001), primarily because of increases in wall thicknesses, beta and the arterial compliance index bore no relation to left ventricular mass. beta was inversely related to chamber diameter and directly related to left ventricular relative wall thickness, the ratio of wall thickness to chamber radius. Younger and older hypertensive subjects had comparable left ventricular mass, despite higher systolic and pulse pressures in the older group, whereas older hypertensives had higher mean relative wall thickness, associated with a significant increase in arterial stiffness (beta, 7.06 versus 5.17; elastic modulus, 595 versus 437 dyne/cm(2) x10(-6)) and reduction in the arterial compliance index (0.87 versus 1.05 mL/mm Hg per square meter) (all P<0.001). Thus, the extent to which arterial stiffness relates to left ventricular hypertrophy is dependent on the method by which arterial stiffness is estimated. Pressure-dependent methods show an association with left ventricular hypertrophy, whereas the pressure-independent stiffness index, beta, and the arterial compliance index are most strongly associated with aging and left ventricular concentric remodeling but not hypertrophy.

Aged↗
PubMed1999

Cardiac and arterial target organ damage in adults with elevated ambulatory and normal office blood pressure.

BACKGROUND: Ambulatory blood pressure may be higher or lower than clinic blood pressure. Attention has focused on "white coat hypertension" (normal ambulatory blood pressure elevated in the clinic). The converse phenomenon of high ambulatory blood pressure but normal office blood pressure-"white coat normotension"-has not been studied. OBJECTIVE: To assess whether white coat normotension (awake ambulatory blood pressure > 134/90 mm Hg and clinic blood pressure < 140/90 mm Hg) is associated with target organ damage. DESIGN: Cross-sectional observational study. SETTING: University hospital hypertension center and participant work sites. PATIENTS: 295 clinically normotensive adults and 64 patients with sustained hypertension (elevated clinic and ambulatory blood pressure). MEASUREMENTS: Target organ abnormalities were measured by echocardiography and arterial ultrasonography in 61 patients with white coat normotension, 234 with sustained normotension (normal clinic and ambulatory blood pressure), and 64 with sustained hypertension. RESULTS: Patients with white coat normotension were older; had higher body mass indices, serum creatinine concentrations, and glucose levels; and a higher prevalence of current smokers. Left ventricular mass index and relative wall thickness were higher by 13 g/m2 (CI, 8 to 18 g/m2) and by 0.03 (CI, 0.01 to 0.04), respectively, in patients with white coat normotension compared with those who had sustained normotension. Patients with white coat normotension and those with sustained hypertension did not differ significantly for left ventricular mass index (4 g/m2 [CI, - 3 to 10 g/m2) or relative wall thickness (0.01 [CI, -0.01 to 0.03]). The prevalence of discrete atherosclerotic plaques was similar in patients with white coat normotension (17 of 61, or 28% [CI, 17% to 39%]) and those with sustained hypertension (17 of 64, or 27% [CI, 16% to 38%]), but the difference lost significance after adjustment for age. CONCLUSIONS: White coat normotension is associated with left ventricular mass and carotid wall thickness similar to those in sustained hypertension. The association of white coat normotension with prognostically important target organ damage may partly explain the ability of high normal left ventricular mass and high normal clinic blood pressure to predict subsequent hypertension and cardiovascular events in patients with clinical normotension.

Adult↗