Search PubMed⌕ Search

Biomedical subjects

R S Crow

Publications and source records attributed to R S Crow.

41 records · Page 3Linked to original sources
PubMed1975

Ventricular premature beats in a population sample. Frequency and associations with coronary risk characteristics.

In a large epidemiological survey, 10,880 men aged 35 to 57 years were screened for ectopic ventricular activity and estimated risk of future coronary heart disease death. A 2-minute lead I electrocardiogram (ECG) was recorded for each man, together with measurement of serum cholesterol, blood pressure, and the number of cigarettes currently smoked. Ventricular premature beats (VPB) occurred in 540 (4.96%) men; of these 459 (4.21%) were uniform, while complex forms were detected in only 7/1000 men. VPB occurring with a frequency of greater than or equal to 10 in the 2-min recording were also rare, occurring in 9/1000 men. No relation was found between the frequency of simple or complex VPB and estimated coronary risk status or between the prevalence of VPB and the individual risk factors of diastolic blood pressure, cholesterol, or cigarette smoking. There was, however, a strong positive association between VPB and the level of systolic blood pressure, and between VPB and increasing age. The lack of association between VPB and overall coronary risk status indicates that myocardial "ischemic" changes in high-risk men may not have progressed sufficiently to alter ventricular excitability or to increase the frequency of VPB.

Adult↗
PubMedDate not supplied

Exercise testing early after myocardial infarction: historic perspective and current uses.

Exercise testing performed earlier than six weeks post-MI is accepted as "standard" medical practice. Although both heart rate-limited and symptom-limited exercise protocols are used with nearly equal frequency, the latter appears more valuable because the prognostic yield is greater without sacrificing patient safety. Treadmill or cycle ergometers are the preferred modes of testing because of higher exercise work loads imposed and increased sensitivity and specificity of results. The physiologic exercise responses to graded work loads among these acute MI survivors include a mean maximal heart rate range of 118 to 136 beats/min, a peak systolic blood pressure between 137 and 170 mmHg, a mean peak double product from 16,000 to 22,400, and a mean maximal work load between 4.8 and 7.0 METS. Exercise findings which are most clinically useful are greater than 1 mm ST segment depression from rest level, presence of angina pectoris during exercise, decrease in systolic blood pressure with increasing work, presence of complex or frequent VEBs, and exercise tolerance less than 4 METS. These exercise findings identify, in recent post-MI survivors, groups of patients that have significantly different estimated future cardiac morbidity and mortality rates. The most consistent indices of multi-vessel coronary heart disease are ST segment depression, angina pectoris, and poor exercise tolerance. The most important role of stress testing in this period post-MI is identification of individuals who urgently need evaluation for coronary bypass surgery. In addition to risk stratification, exercise testing provides valuable information regarding exercise prescription for cardiac rehabilitation, direct psychologic benefit for resuming an active lifestyle, and motivation for exercise participation. Although safety of the early post-MI stress test has not been systematically studied, reports from individual studies indicated low morbidity and mortality. Attesting to this is the frequency with which it is performed as a routine office procedure. Finally, there has been a growing use of this procedure not only among cardiologists but also among internists and family practice physicians.

Angina Pectoris↗
PubMedDate not supplied

The promotion of physical activity in the United States population: the status of programs in medical, worksite, community, and school settings.

While the medical care encounter is considered an ideal situation in which patients are encouraged to increase their physical activity levels, very little research has been conducted in this setting. In fact, with the exception of the physical activity components of cardiac rehabilitation programs, few formal physical activity programs are available in medical care settings. Although the workplace is currently the focus of the greatest interest by those persons who implement physical activity programs, there is little precision in defining what constitutes a worksite physical activity program. A number of researchers and authors, using program experience rather than empirical findings, have described what they believe to be the important components of successful worksites health promotion and physical education programs. The greatest variety of physical activity programs are found in community settings. They are offered by a number of nonprofit private organizations, nonprofit public agencies, and for-profit organizations. While relatively little research has been done concerning changes in the community environment, it is clear that such changes can effect community participation. Community campaigns to increase physical activity have been studied, and it appears that they clearly affect residents' interest and awareness in physical activity, but they do not have a major effect on behavioral changes in the short term. It appears that a major opportunity to influence favorable physical activity in the United States is being missed in schools. A large majority of students are enrolled in physical education classes, but the classes appear to have little effect on the current physical fitness levels of children and, furthermore, have little impact on developing life-long physical activity skills.

Adolescent↗