Biomedical subjects
Publications and source records attributed to M N Walsh.
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OBJECTIVES: This survey was conducted to learn how the career decisions of women and men in cardiology influenced their professional and personal lives. BACKGROUND: Women represent only 5% of practicing adult cardiologists and 10% of trainees. Yet, women and men now enter medical school at nearly equal numbers. The factors that contribute to career satisfaction in cardiology should be identified to permit the development of future strategies to ensure that the best possible candidates are attracted to the profession. METHODS: A questionnaire developed by the Ad Hoc Committee on Women in Cardiology of the American College of Cardiology (ACC) was mailed in March 1996 to all 964 female ACC members and an age-matched sample of 1,199 male members who had completed cardiovascular training. RESULTS: Women were more likely to describe their primary or secondary role as a clinical/noninvasive than invasive cardiologist (p < 0.0001 women vs. men). Men and women both reported a high level of satisfaction with family life, but women were less satisfied with their work as cardiologists (88% vs. 92%, p < 0.01) and with their level of financial compensation. Compared with men, women expressed less overall satisfaction (69% vs. 84%) and more dissatisfaction with their ability to achieve professional goals (21% vs. 9%). These differences were most pronounced for women in academic practice. Women reported greater family responsibilities, which may limit their opportunities for career advancement. Women were more likely to alter training or practice focus to avoid radiation. A majority of women (71%) reported gender discrimination, whereas only 21% of men reported any discrimination, largely due to race, religion or foreign origin. CONCLUSIONS: Women cardiologists report overall lower satisfaction with work and advancement, particularly within academic practice. They report more discrimination, more concerns about radiation and more limitations due to family responsibilities, which may ultimately explain the low percentage of women in cardiology. Attention to these issues may result in programs to improve professional satisfaction and attract the best candidates into cardiology in the future.
OBJECTIVE: To rank 39 surgical procedures in order of variation of inpatient surgical rates, according to a new index of variation and to test the hypothesis that there is greater variation for primarily discretionary operations than for primarily non-discretionary operations. DESIGN: A population-based retrospective cohort study. SETTING: Nine provinces (99.19% of Canada's population). PARTICIPANTS: All hospital inpatients who underwent any of 39 types of surgery and were separated from hospital between Apr. 1, 1988 and Mar. 31, 1990 (the most recent time period for which Canada-wide data were available at the subprovincial level analysed). MAIN OUTCOME MEASURE: Rankings of the 39 procedures according to the index of variation, calculated from inpatient surgery rates in 255 census divisions across Canada. RESULTS: The 13 procedures with the greatest variation were all primarily discretionary. Thirteen of the 14 procedures with the lowest variation were primarily non-discretionary. All but one of the procedures whose degree of discretion was deemed intermediate were in the middle third of the rankings. CONCLUSIONS: The greatest variation is found in primarily discretionary operations. Further investigation should be focused on identified geographical locations where rates for operations that are primarily discretionary are unusually high or low, and particularly on those operations for which there is disagreement regarding the indications for surgery.
This paper identifies outliers (unusually high or low values) among rates of 39 surgical procedures in 255 Canadian census divisions. Surgery rates for the two-year period from April 1988 through March 1990 were standardized for age and sex, and then "normalized" to adjust for differences in census division population sizes. Among the 39 procedures, a total of 402 outlying census division rates were found, of which 48 were deemed to be very high, 254 high, 79 low, and 21 very low. The results are presented for individual procedures, by province, and for the 16 census divisions in which medical schools and their associated teaching hospitals are located.
A randomized single-blind study was performed comparing a reusable 8 French bioptome with a single-use 7 French bioptome in a consecutive series of 63 myocardial biopsy procedures performed during follow-up of cardiac transplant patients. Safety, efficacy and cost were compared between 30 procedures performed with the single-use bioptome (Group I) and 33 procedures performed with the reusable bioptome (Group II). The two instruments were found equally efficient in obtaining adequate biopsy samples (69% of attempts for both instruments). The average specimen weight was not significantly different (Group I 2.5+/-1.3 mg, Group II 2.7+/-1.1 mg) despite different nominal jaw sizes. There was no significant difference in the incidence of incompletely cut specimens (Group I 13%, Group II 7%) and there were no complications in either group. The cost of the two instruments was, as expected, markedly different with an estimated average per-use cost of $250.00 for the single-use bioptome and $35.89 for the reusable instrument. In this small study, a single-use 7 French myocardial bioptome was found to be an acceptable substitute for the larger, reusable instrument with no decrement in specimen size. The substantial cost differential is noteworthy, although the maintenance required by the reusable instrument can present a formidable challenge.
Effects of coronary angioplasty on myocardial flow reserve have been difficult to characterize noninvasively because conventional imaging techniques cannot quantitate blood flow in absolute terms. The effects of coronary angioplasty on myocardial perfusion and perfusion reserve were delineated with positron emission tomography and oxygen-15-labeled water (H2(15)O) in 13 patients before and after single vessel angioplasty. In 11 patients, angioplasty was successful (minimal cross-sectional area increased from 0.60 +/- 0.59 to 3.45 +/- 1.09 mm2, p less than 0.001). In these patients, regional H2(15)O radioactivity (the ratio of nutritional perfusion in regions distal to the stenosis compared with regions supplied by angiographically normal arteries) at rest before angioplasty was 55 +/- 22% of peak myocardial radioactivity and did not increase significantly afterward (70 +/- 16%, p = NS). However, after administration of intravenous dipyridamole, hyperemic perfusion in regions distal to a stenosis averaged only 39 +/- 18% of peak myocardial counts before angioplasty, but increased to 66 +/- 22% after angioplasty (p less than 0.02). Perfusion reserve in the two patients in whom angioplasty was angiographically unsuccessful showed no change. Quantitative estimates of perfusion in absolute rather than relative terms were obtained with positron emission tomographic data from seven of the patients with successful angioplasty. At rest, perfusion in regions distal to a stenosis was not different from the values in regions supplied by normal coronary arteries (1.54 +/- 0.54 compared with 1.46 +/- 0.38 ml/g per min, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Noninvasive measurement of myocardial blood flow in absolute terms (i.e., milliliters per gram per min) has been difficult to accomplish despite the intrinsically quantitative power of positron emission tomography because of the nonphysiologic nature of tracers that have been employed conventionally as well as the limited spatial resolution of currently available instruments. It was previously demonstrated that myocardial blood flow in animals can be quantitated accurately with the diffusible tracer oxygen-15-labeled water (H2(15)O) when the arterial input function and myocardial radiotracer concentration were measured directly. To extend the approach for completely noninvasive measurement of blood flow, a parameter estimation procedure was developed whereby effects of limited tomographic spatial resolution and cardiac motion were compensated for within the operational flow model. In validation studies in 18 dogs, myocardial blood flow measured with positron emission tomography after intravenously administered H2(15)O correlated closely with flow measured with concomitantly administered radiolabeled microspheres over the range of 0.29 to 5.04 ml/g per min (r = 0.95). Although regional ischemia was clearly identifiable tomographically, absolute flow could not be determined accurately in ischemic regions in four dogs because of poor count statistics related to wall thinning. Subsequently, myocardial blood flow was measured in 11 normal human subjects. Flow was homogeneous throughout the myocardium, averaged 0.90 +/- 0.22 ml/g per min at rest and increased to 3.55 +/- 1.15 ml/g per min after intravenous administration of dipyridamole. Therefore, positron emission tomography with H2 15O and the approach developed permits noninvasive measurement of myocardial blood flow in absolute terms in humans and should facilitate objective assessment of interventions designed to enhance nutritive perfusion.
We have previously demonstrated that positron emission tomography (PET) with [11C]acetate allows noninvasive regional quantification of myocardial oxidative metabolism. To assess the metabolic response of normal myocardium to increased work (oxidative metabolic reserve), clearance of myocardial 11C activity after administration of [11C]acetate i.v. was measured with PET in seven normal subjects at rest and during dobutamine infusion. At rest, clearance of 11C was monoexponential and homogeneous. The rate constant of the first phase of 11C clearance, k1, averaged 0.054 +/- 0.014 min-1 at a rate-pressure produce (RPP) of 7329 +/- 1445 mmHg X bpm. During dobutamine infusion, RPP increased by an average of 141% to 17,493 +/- 3582 mm Hg Z bpm. Clearance of 11C became biexponential and remained homogeneous. k1 averaged 0.198 +/- 0.043 min-1 with a mean coefficient of variation of 16%.. k1 and RPP correlated closely (r = 0.91; p less than 0.001), and the slope of the k1/RPP relation remained consistent in all subjects (1.48 +/- 0.42). These findings suggest that PET with [11C]acetate and dobutamine stress may provide a promising approach for evaluation of regional myocardial oxidative metabolic reserve in patients with cardiac diseases of diverse etiologies and for assessment of the efficacy of interventions designed to enhance the recovery of metabolically comprised myocardium.
We previously demonstrated in experimental studies that myocardial oxygen consumption (MVO2) can be estimated noninvasively with positron emission tomography (PET) from analysis of the myocardial turnover rate constant (k) after administration of carbon-11 (11C) acetate. To determine regional k in healthy human subjects and to estimate alterations in MVO2 accompanying myocardial ischemia, we administered [11C]acetate to five healthy human volunteers and to six patients with myocardial infarction. Extraction of [11C]acetate by the myocardium was avid and clearance from the blood-pool rapid yielding myocardial images of excellent quality. Regional k was homogeneous in myocardium of healthy volunteers (coefficient variation = 11%). In patients, k in regions remote from the area of infarction was not different from values in myocardium of healthy human volunteers (0.061 +/- 0.025 compared with 0.057 +/- 0.008 min-1). In contrast, MVO2 in the center of the infarct region was only 6% of that in remote regions (p less than 0.01). In four patients studied within 48 hr of infarction and again more than seven days after the acute event, regional k and MVO2 did not change. The approach developed should facilitate evaluation of the efficacy of interventions designed to enhance recovery of jeopardized myocardium and permit estimation of regional MVO2 and metabolic reserve underlying cardiac disease of diverse etiologies.
Positron emission tomography with 15O-labeled water (H2(15)O) can be used to delineate abnormal regional myocardial blood flow in experimental animals. To determine the feasibility of this method in humans, we studied 33 subjects (9 normal volunteers and 24 patients with angiographically documented coronary artery disease) at rest and after myocardial hyperemia induced with intravenous infusion of dipyridamole. At rest, the myocardial region demonstrating the lowest relative H2(15)O activity exhibited 71 +/- 8% of activity in the region with peak activity in control subjects and 62 +/- 17% in patients (p = NS). After the dipyridamole infusion, differences between the two groups were accentuated. In control subjects, activity in the region with lowest relative radioactivity averaged 77 +/- 5% of that in the region with peak activity. In patients, it averaged 55 +/- 22% of activity in the region with peak activity (p less than 0.01). Results in patients with ischemia with or without a history of remote myocardial infarction were not significantly different. In 22 of the 24 patients, the region with lowest relative perfusion corresponded anatomically to the region of myocardium distal to a stenosis. Thus, delineation of regional myocardial perfusion in patients with coronary artery disease is possible with positron emission tomography and H2(15)O. Further studies will be necessary to prospectively determine sensitivity and specificity.
Lumbar puncture (LP) is sometimes performed in addition to computed tomography (CT) to exclude hemorrhage prior to anticoagulation for suspected cerebral ischemia. The LP may be complicated by spinal hemorrhage during subsequent anticoagulation. We report such a case with an eventually fatal outcome due to intracranial extension of blood. On balance, the use of LP in addition to CT in this setting appears to be unwise.
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