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Biomedical subjects

R Crow

Publications and source records attributed to R Crow.

At least 37 records · Page 2Linked to original sources
PubMed1993

Improved ECG models for estimation of left ventricular hypertrophy progression and regression incidence by redefinition of the criteria for a significant change in left ventricular hypertrophy status. The MRFIT Research Group. Multiple Risk Factor Intervention Trial.

Three sets of left ventricular hypertrophy (LVH) criteria were evaluated in terms of their utility for LVH progression and regression incidence estimation. Incidence comparisons were performed with and without taking short-term variability into consideration using electrocardiographic records taken at the baseline and the first annual follow-up examination of 11,969 men, aged 37 to 55 years, at the baseline of the Multiple Risk Factor Intervention Trial. Short-term total technical and biologic variability (95% range) was determined from the records of 104 men invited for a repeat electrocardiographic recording at 2-week or shorter intervals from the first recording. The results indicated that after elimination of the false fraction due to normal variability, the residual incidence estimates are so low that their utility and statistical power in monitoring changes in LVH status is very limited. It is concluded that a redefinition of LVH progression and regression criteria is needed to enhance their utility in clinical trials.

Adult↗
PubMed1992

Intermittent ST depression and mortality after myocardial infarction.

BACKGROUND: We conducted a case-control analysis to determine the contribution made to mortality by intermittent ST depression (STD) among patients enrolled in the already completed Beta Blocker Heart Attack Trial. METHODS AND RESULTS: STD was determined by computer analysis of 24-hour ECG tapes as a change in ST level by +/- 0.1 mV or more from the median value of ST of all normally conducted complexes for greater than or equal to 1 minute. All computer-detected ST events were verified by trained readers. To estimate risk of dying associated with STD, 261 deaths were compared with controls matched for age, sex, drug status, and time elapsed since acute myocardial infarction. In a model including relevant covariates, STD had a relative risk (RR) of 1.73 (95% confidence interval, 1.09-2.73). The RR was 2.56 (1.39-4.71) in untreated patients and 0.98 (0.48-2.00) in propranolol-treated patients. A history of angina, although not independently significant, was found to enhance these RRs. A gradient of risk was shown in the placebo group by a RR of 1.91 in those with 1-30 minutes of STD and 4.33 in those with greater than 30 of STD (p = 0.001, trend test). CONCLUSIONS: The findings in this large study show a significant contribution to mortality among untreated early post-myocardial infarction survivors from transient STD on 24-hour monitoring. The absence or reduction of effect in the treated group also suggests an anti-ischemic mechanism by which propranolol exerts a protective effect on mortality. Trials to determine whether reduction of STD improves survival would be warranted.

Adult↗
PubMed1992

Symptom-limited graded treadmill exercise testing in young adults in the CARDIA study.

Symptom-limited, graded exercise treadmill testing was performed by 4,968 white and black adults, ages 18-30 yr, during the baseline examination for the CARDIA study. The mean estimated maximal exercise capacity by race/gender, expressed as metabolic units (METS), was: white men 13.8, black men 13.0, white women 11.1, and black women 9.4. Exercise test duration was higher in nonsmokers, positively related to physical activity score and pulmonary function (FEV1.ht-2), and inversely related to body mass index. Men had higher mean values than women for both test duration and a measure of submaximal performance, the workload 130 (WL130, the exercise test duration to a heart rate of 130 beats.min-1). Adjusted for age and education, white men had a longer mean test duration than black men (53 s longer, P less than 0.001), but nearly equal mean WL130. White women had higher mean values than black women for both test duration (114 s longer, P less than 0.001) and WL130 (36 s longer, P less than 0.001). Men had higher mean values than women for both outcome measures (P less than 0.001). Thus, in young adults significant gender and ethnic differences exist for exercise test performance, part of which can be explained by personal habits or traits.

Adolescent↗
PubMed1991

Secular trends in Q wave and non-Q wave acute myocardial infarction. The Minnesota Heart Survey.

The Minnesota Heart Survey examined trends of Q wave and non-Q wave acute myocardial infarction (AMI) using a 50% random sample of all hospital discharges of patients with AMI or another acute coronary disease from 35 of 36 hospitals in 1970 and 30 of 31 hospitals in 1980 in the Minneapolis-St. Paul metropolitan area. A total of 1,901 and 1,864 potential AMI cases were abstracted in 1970 and 1980, respectively. Electrocardiograms were coded according to the Minnesota code. AMIs were validated by computerized algorithm based on chest pain, enzymes, electrocardiograms, and autopsy. This study shows that with the use of a consistent, standard diagnostic algorithm, attack rates for Q wave AMI did not change significantly between 1970 and 1980 and that attack rates for non-Q wave AMI decreased significantly during the same decade. However, when the more sensitive cardiac enzymes creatine phosphokinase and creatine phosphokinase-MB were considered, attack rates of both Q wave and non-Q wave AMIs increased. This research documents four important trends for community AMI rates that are at variance with those reported by others. There was a decline in non-Q wave AMI attack rates from 1970 to 1980; women had outcomes equal to or worse than those for men for both case-fatality and 7-year survival rates; patients with non-Q wave AMIs had worse in-hospital prognoses than those with Q wave AMIs; and 7-year survival rates were worse for Q wave AMI in 1980. These findings demonstrate the need for standard diagnostic criteria for Q wave and non-Q wave AMI if trends are to be monitored. In the future, as new trials of operative and nonoperative therapies of AMI are undertaken, these considerations will increase in importance.

Adult↗
PubMed1990

The effect of the number of electrocardiograms analyzed on cardiovascular disease surveillance: the Minnesota Heart Survey (MHS).

One method used to control costs in community cardiovascular disease surveillance is to limit the number of electrocardiograms (ECGs) used to validate acute myocardial infarction (AMI). The Minnesota Heart Survey investigated the impact of decreasing the maximum number of ECGs analyzed on classification of ECG pattern and final AMI diagnosis (definite, probable, none). A 50% sample of all 1980 acute CHD hospital discharge records (ICD-9 code 410 or 411) from 30 of 31 Twin Cities hospitals were abstracted. Comparing results using all available ECGs in the record (maximum of 12) with those obtained using up to 4 ECGs showed little differences in the ECG classification or final AMI diagnosis.

Electrocardiography↗
PubMed1989

Electrocardiographic left ventricular hypertrophy and effects of antihypertensive drug therapy in hypertensive participants in the Multiple Risk Factor Intervention Trial.

Data are reported on electrocardiographic left ventricular hypertrophy (ECG LVH) among 8,012 men classified as hypertensive at baseline in the Multiple Risk Factor Intervention Trial. Compared with those allocated to the usual care (UC) control group, men allocated to the special intervention (SI) group experienced a mean reduction of 4 mm Hg in diastolic blood pressure and 7 mm Hg in systolic blood pressure, over 6 years of follow-up. There were 378 new cases of ECG LVH during follow-up; the incidence in the SI group was about 23% less than that in the UC group (4.2 vs 5.4% 2P less than 0.01). Among the 189 men with ECG LVH at baseline, those in the SI group experienced about 24% more annual follow-up visits at which they were free of ECG LVH (4.6 vs 3.7 visits; 2P less than 0.01). This reduced incidence and increased reversal of ECG LVH in the SI group compared with that in the UC group was consistent with significant overall reductions (2P less than 0.001) among SI men in mean wave amplitude in those leads in which voltage is correlated with left ventricular mass (T wave in V1, R wave in aVL and S wave in V3). In SI and UC groups combined, the presence of ECG LVH either at baseline or at follow-up was associated with several-fold increases in death from cardiovascular diseases in general, and death from coronary artery disease in particular.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Cardiac status after four years in a trial on nutritional therapy for high blood pressure.

A randomized controlled trial demonstrated the ability of nutritional intervention in place of antihypertensive drugs to maintain blood pressure at normal levels for four years in 39% of less severely hypertensive patients whose blood pressure was previously well controlled by pharmacologic treatment. However, average blood pressures during the trial for patients in the intervention group were higher than those for a comparison group that continued to receive drug therapy throughout the study. Holter monitoring, echocardiography, roentgenography, and electrocardiography done at four years to determine whether blood pressure differences between groups were associated with differences in cardiac status did not indicate any differences in cardiac status favorable to one group compared with the other. Further investigation in larger samples is needed to assess any long-term differences in cardiac status based on such alternate therapies.

Adult↗
PubMed1988

Indwelling catheterization and related nursing practice.

A survey of patients with an indwelling urethral catheter was conducted over a 14-day period in five randomly selected district general hospitals in England. The demographic characteristics of the patients and the types of catheter and urinary drainage bags used were recorded. Observational techniques were used to describe nursing care during meatal cleansing and bag emptying Over the 14-day study period 294 patients were catheterized giving an overall daily incidence of catherization of 11.2 per 1000 of the average daily population. Nurses inserted over 50% of catheters and subsequently maintained all closed urinary drainage systems. The closed system was broken for 42% of patients and only 48% of drainage bags were always observed in the correct position. Techniques aimed at preventing infection were observed more frequently when meatal cleansing was performed separately from daily hygiene. The frequency of hand washing, both before and after meatal cleansing and bag emptying, was low. It is concluded that the procedures and practices involved in the care of the urinary drainage system require re-evaluation and re-emphasis.

Adult↗
PubMed1986

Population strategies to enhance physical activity: the Minnesota Heart Health Program.

A population-wide, community-based program in cardiovascular disease prevention, the Minnesota Heart Health Program (MHHP), has been designed to promote more frequent and vigorous physical activity in North American communities, along with improved eating and smoking patterns. The physical activity component of this broad-based education strategy is based on the facilitation which physical activity provides to lowering of other risk characteristics for heart disease and its enhancement of other healthy behaviors and on the potential for prevention of elevated risk in the first place. The rationale for a population strategy to complement medical approaches to prevention is that exercise patterns are largely socially learned and culturally determined. The MHHP Physical Activity Program is implemented through three major education strategies: direct education, community organization, and mass communications. Early results from this 10-year project indicate that it is feasible to enter U.S. communities and to involve their leadership actively in MHHP activities of health promotion. Moreover, attitudes, knowledge, awareness, participation, and behaviors related to exercise and eating patterns appear to be changed by the program. Nevertheless, there are problems in the design, implementation, analysis and interpretation of population changes in physical activity and other health behaviors in community demonstration programs. These issues, along with their solutions, should provide useful information for medical science and for the public health about population strategies of disease prevention and health promotion.

Adolescent↗
PubMed1982

Frontiers of nursing in the twenty-first century: development of models and theories on the concept of nursing.

Theories and models on the concept of nursing are reviewed briefly and their contribution then assessed in terms of their potential to advance the scientific basis of nursing practice. The constructs are acknowledged to have moved the focus of nursing from disease to patient need and provided different ways of looking at the nurse's contribution. Yet, despite this advance, the constructs have not been put to the rigours of scientific testing and so remain at the level of speculation. Therefore, towards the developments for the twenty-first century it is proposed that these ideas should be put to the test to establish their relevance in the real world of nursing care. This requires: a framework from which the nature, extent and purpose of care can be specified; independent criteria which can be used to judge effectiveness of care; knowledge as it relates to the different and varied core concepts underlying the practice of nursing; and a working definition of need. In addition, the extent of care for the community needs to be made explicit through research. Together, this represents a challenge to develop theories which are logically related to single core concepts which themselves represent specific areas of actual nursing practice.

Models, Theoretical↗