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Peter Collins

Publications and source records attributed to Peter Collins.

43 records · Page 3Linked to original sources
PubMed2002

Clinical cardiovascular studies of hormone replacement therapy.

Coronary artery disease (CAD) is the number 1 cause of death and disability in the Western world. The incidence of CAD increases with age, although, on average, women present with symptomatic CAD about 10 years later than men. The belief that hormone replacement therapy (HRT) may reduce the incidence of CAD is based on its favorable effects on (1) vasoreactivity, (2) progression of atherosclerosis, (3) lipids and lipoproteins, (4) hemostasis, and (5) impaired glucose tolerance. However, unopposed estrogen may be related to an increased risk of endometrial cancer. The belief that HRT has an overall beneficial effect on cardiovascular disease comes from the results of prospective cohort studies. The Heart and Estrogen/progestin Replacement Study (HERS), however, showed no beneficial effect of HRT on cardiovascular morbidity and mortality. Uncertainty exists about the duration and optimal type of HRT regimen to use, because different estrogens and progestins have yielded different results. Results of ongoing trials addressing similar questions will be published in future years. The Women's Hormone Intervention Secondary Prevention (WHISP) pilot study, using a different HRT regimen from that used in HERS, will assess the effect of HRT on lipid and hemostatic risk markers of heart disease, and it may provide the rationale for a large trial evaluating the effect of HRT on morbidity and mortality.

Adult↗
PubMed2002

Comparison of interstudy reproducibility of cardiovascular magnetic resonance with two-dimensional echocardiography in normal subjects and in patients with heart failure or left ventricular hypertrophy.

Fast breath-hold cardiovascular magnetic resonance (CMR) shows excellent results for interstudy reproducibility of left ventricular (LV) volumes, ejection fraction, and mass, which are thought to be superior to results of 2-dimensional echocardiography. However, there is no direct comparison of the interstudy reproducibility of both methods in the same subjects. A total of 60 subjects (normal volunteers [n = 20], or patients with heart failure [n = 20] or LV hypertrophy [n = 20]) underwent 2 CMRs and 2 echocardiographic studies for assessment of LV volumes, function, and mass. The interstudy reproducibility coefficient of variability was superior for CMR in all groups for all parameters. Statistical significance was reached for end-systolic volume (4.4% to 9.2% vs 13.7% to 20.3%, p <0.001), ejection fraction (2.4% to 7.3% vs 8.6% to 19.4%, p <0.001), and mass (2.8% to 4.8% vs 11.6% to 15.7% p <0.001), with a trend for end-diastolic volume (2.9% to 4.9% vs 5.5% to 10.5%, p = 0.17). The superior interstudy reproducibility resulted in considerably lower calculated sample sizes (reductions of 55% to 93%) required by CMR compared with echocardiography to show clinically relevant changes in LV dimensions and function. Thus, CMR has excellent interstudy reproducibility in normal, dilated, and hypertrophic hearts, and is superior to 2-dimensional echocardiography.

Adult↗
PubMed2002

Abnormal subendocardial perfusion in cardiac syndrome X detected by cardiovascular magnetic resonance imaging.

BACKGROUND: In cardiac syndrome X (a syndrome characterized by typical angina, abnormal exercise-test results, and normal coronary arteries), conventional investigations have not found that chest pain is due to myocardial ischemia. Magnetic resonance techniques have higher resolution and therefore may be more sensitive. METHODS: We performed myocardial-perfusion cardiovascular magnetic resonance imaging in 20 patients with syndrome X and 10 matched controls, both at rest and during an infusion of adenosine. Quantitative perfusion analysis was performed by using the normalized upslope of myocardial signal enhancement to derive the myocardial perfusion index and the myocardial-perfusion reserve index (defined as the ratio of the myocardial perfusion index during stress to the index at rest). RESULTS: In the controls, the myocardial perfusion index increased in both myocardial layers with adenosine (in the subendocardium, from a mean [+/-SD] of 0.12+/-0.03 to 0.16+/-0.03 [P=0.02]; in the subepicardium, from 0.11+/-0.02 to 0.17+/-0.05 [P=0.002]); in patients with syndrome X, the myocardial perfusion index did not change significantly in the subendocardium (0.13+/-0.02 vs. 0.14+/-0.03, P=0.11; P=0.09 as compared with controls) but increased in the subepicardium (from 0.11+/-0.02 to 0.20+/-0.04, P<0.001; P=0.11 for the comparison with controls). Adenosine provoked chest pain in 95 percent of patients with syndrome X and 40 percent of controls (P<0.001). CONCLUSIONS: In patients with syndrome X, cardiovascular magnetic resonance imaging demonstrates subendocardial hypoperfusion during the intravenous administration of adenosine, which is associated with intense chest pain. These data support the notion that the chest pain may have an ischemic cause.

Adenosine↗
PubMed2002

A comparison of brachial artery reactivity measured by external and intravascular ultrasound.

External ultrasound (US), EXUS, is widely used to measure brachial artery (BA) diameter changes in the assessment of vascular function; however, it has not been compared with other imaging modalities. We simultaneously measured BA diameter responses to hyperaemic flow and nitrate using EXUS and intravascular ultrasound (US), IVUS, in 10 patients. Mean diameters measured across all time periods correlated closely (r = 0.67, p < 0.001). Percent diameter change to hyperaemia and nitrate also correlated well (r = 0.67, p < 0.01). IVUS cross-sectional area (CSA) was significantly different from that calculated from EXUS using pir(2) (23.95 +/- 4.89 vs. 20.35 +/- 4.51 mm(2), respectively, p < 0.001). Orthogonal diameters measured by IVUS were significantly different (5.45 +/- 0.85 vs. 5.17 +/- 0.79 mm, respectively, p < 0.005). In conclusion, EXUS and IVUS BA diameter measurements correlated well; however, discrepancies in absolute measurements were revealed. The cross-section of the BA is oval; therefore, deriving CSA by pir(2) is inaccurate.

Adult↗
PubMedDate not supplied

The importance of continued exercise participation in quality of life and psychological well-being in previously inactive postmenopausal women: a pilot study.

OBJECTIVE: Exercise and physical activity provide a wide range of health benefits for postmenopausal women, although the impact of maintained exercise participation on psychological well-being is unclear. An exploration of continued exercise participation in psychological well-being after a moderate-intensity exercise program in previously inactive postmenopausal women was therefore undertaken. DESIGN: : Twenty-three healthy sedentary postmenopausal women (age 56 +/- 4 years) were randomly assigned to two groups. All participants completed the Short Form-36, Hospital Anxiety and Depression Scale (HADS), and Health Anxiety Questionnaire (HAQ) and then began a 6-week walking program at 50% heart rate reserve defined by (.-)V(O(2)) treadmill testing. Post-intervention, all participants underwent (.-)V(O(2)) treadmill testing and questionnaires. Group 1 was then instructed to continue exercising, whereas group 2 was instructed to desist for an additional 6-week period. On completion of the 6-week follow-up, participants completed a final set of questionnaires. RESULTS: Participants performed 97% of the prescribed 15-hour (900 minute) exercise program (875.1 +/- 177.4 minutes) in an average of 26 +/- 5 sessions. Total HAQ (P = 0.001), health worry (P = 0.001), fear of illness (P = 0.037), reassurance seeking behavior (P = 0.037), SF-36 well-being (P = 0.037), total HADS (P = 0.019), and HADS depression (P = 0.015) improved significantly following the exercise program. At follow-up, group 1 had lower HADS anxiety (P = 0.013), total HADS (P = 0.02), total HAQ (P = 0.03), and HAQ interference with life (P = 0.03) and significantly higher SF-36 energy (P = 0.01) than group 2. CONCLUSIONS: Healthy postmenopausal women gain significant psychological benefit from moderate-intensity exercise. However, exercise participation must continue to maintain improvements in psychological well-being and quality of life.

Depressive Disorder↗