Optimizing safe femoral access during cardiac catheterization.

This article describes the natural variability of femoral arterial anatomy as seen by angiography in a standard position. An analysis of 60 consecutive peripheral angiograms revealed data on average vessel diameter, variability in that diameter and the level of bifurcation of the common femoral artery into its two main branches. The statistical likelihood of optimal femoral arterial access through a standard dermotomy placed midway between, and 3 cm below, the imaginary line extending from the superior anterior iliac spine to the pubic symphysis was calculated. Our research disclosed average vessel diameters of 6.6 mm (3.9-8.9 mm), 5.2 mm (2.5-9.6 mm), and 4.9 mm (2.7-7.6 mm) for the common femoral artery, superficial femoral artery and deep femoral artery, respectively. The bifurcation of the common femoral artery into its branches averaged 5.5 mm below the inferior margin of the femoral head in most cases (76% of the time). In our laboratory, the average distance from the inferior border of the femoral head to our actual arteriotomy was 14.0 mm. Using our standard dermotomy, we achieved this favorable access position in 97% of cases.

fMR-adaptation: a tool for studying the functional properties of human cortical neurons.

The invariant properties of human cortical neurons cannot be studied directly by fMRI due to its limited spatial resolution. One voxel obtained from a fMRI scan contains several hundred thousands neurons. Therefore, the fMRI signal may average out a heterogeneous group of highly selective neurons. Here, we present a novel experimental paradigm for fMRI, functional magnetic resonance-adaptation (fMR-A), that enables to tag specific neuronal populations within an area and investigate their functional properties. This approach contrasts with conventional mapping methods that measure the averaged activity of a region. The application of fMR-A to study the functional properties of cortical neurons proceeds in two stages: First, the neuronal population is adapted by repeated presentation of a single stimulus. Second, some property of the stimulus is varied and the recovery from adaptation is assessed. If the signal remains adapted, it will indicate that the neurons are invariant to that attribute. However, if the fMRI signal will recover from the adapted state it would imply that the neurons are sensitive to the property that was varied. Here, an application of fMR-A for studying the invariant properties of high-order object areas (lateral occipital complex--LOC) to changes in object size, position, illumination and rotation is presented. The results show that LOC is less sensitive to changes in object size and position compared to changes of illumination and viewpoint. fMR-A can be extended to other neuronal systems in which adaptation is manifested and can be used with event-related paradigms as well. By manipulating experimental parameters and testing recovery from adaptation it should be possible to gain insight into the functional properties of cortical neurons which are beyond the spatial resolution limits imposed by conventional fMRI.

The lateral occipital complex and its role in object recognition.

Here we review recent findings that reveal the functional properties of extra-striate regions in the human visual cortex that are involved in the representation and perception of objects. We characterize both the invariant and non-invariant properties of these regions and we discuss the correlation between activation of these regions and recognition. Overall, these results indicate that the lateral occipital complex plays an important role in human object recognition.

The dynamics of object-selective activation correlate with recognition performance in humans.

To investigate the relationship between perceptual awareness and brain activity, we measured both recognition performance and fMRI signal from object-related areas in human cortex while images were presented briefly using a masking protocol. Our results suggest that recognition performance is correlated with selective activation in object areas. Selective activation was correlated to object naming when exposure duration was varied from 20 to 500 milliseconds. Subjects' recognition during identical visual stimulation could be enhanced by training, which also increased the fMRI signal. Overall, the correlation between recognition performance and fMRI signal was highest in occipitotemporal object areas (the lateral occipital complex).

Endotracheal cardiac output monitor.

BACKGROUND: The endotracheal cardiac output monitor (ECOM) is a new device that uses an endotracheal tube with multiple electrodes to measure cardiac output (CO). It measures the changes in electrical impedance caused by pulsatile blood flow in the aorta. The system was tested for safety and efficacy in 10 swine. METHODS: Swine (60-80 kg) were chronically instrumented with a transit time flow probe on the ascending aorta and vascular occluders on the vena cava and pulmonary artery. After a minimum recovery of 4 days, the animals were anesthetized and intubated with an ECOM endotracheal tube. CO measurements from the ECOM system were compared to transit time flow probe measurements using linear regression and Bland-Altman analysis. Three different inotropic states were studied: (1) baseline; (2) increased (dobutamine); and (3) decreased (esmolol). CO was changed at each inotropic state by impeding left ventricular filling with the vena cava or pulmonary artery occluders. CO values between 0 and 15 l/min were studied. Pigs were studied for 24 h consecutively. RESULTS: There was no deterioration of the impedance signal with time and no tracheal injury from the ECOM electrodes. There is a linear relationship between the ECOM and transit time flow probe CO between 0 and 15 l/min (slope = 0.94; intercept = 0.15 l/min; R2= 0.77). The mean difference between the two measures (bias) is 0.15 l/min and the SD is 1.34 l/min. The limits of agreement are -2.53 to 2.82 l/min. CONCLUSION: Endotracheal CO monitor is a promising technology that needs further evaluation in clinical trials.

Differential processing of objects under various viewing conditions in the human lateral occipital complex.

The invariant properties of human cortical neurons cannot be studied directly by fMRI due to its limited spatial resolution. Here, we circumvented this limitation by using fMR adaptation, namely, reduction of the fMR signal due to repeated presentation of identical images. Object-selective regions (lateral occipital complex [LOC]) showed a monotonic signal decrease as repetition frequency increased. The invariant properties of fMR adaptation were studied by presenting the same object in different viewing conditions. LOC exhibited stronger fMR adaptation to changes in size and position (more invariance) compared to illumination and viewpoint. The effect revealed two putative subdivisions within LOC: caudal-dorsal (LO), which exhibited substantial recovery from adaptation under all transformations, and posterior fusiform (PF/LOa), which displayed stronger adaptation. This study demonstrates the utility of fMR adaptation for revealing functional characteristics of neurons in fMRI studies.

Diabetic cardiomyopathy.

Prior to 1972, the increased cardiovascular morbidity and mortality that diabetics endure had been attributed to vascular disease. In 1972, Rubler et al. proposed the existence of a diabetic cardiomyopathy based on their expereince with four adult diabetic patients who suffered from congestive heart failure (CHF) in the absence of discernable coronary artery disease, valvular or congenital heart disease, hypertension, or alcoholism. Alternative explanations for CHF, such as anemia and vascular and renal disease in these four patients, gave rise to criticisms, but a wave of subsequent studies in the 1970s and 1980s provided credence to this new disease entity. This review of the studies done since 1972 appears to support the concept of a diabetic cardiomyopathy independent of atherosclerotic cardiovascular disease. The exact mechanism is still questionable, and several mechanisms have been proposed including small and microvascular disease, autonomic dysfunction, metabolic derangements, and interstitial fibrosis. However, the weight of evidence leans toward the development of fibrosis, possibly caused by the accumulation of a peroxidase acid schiff (PAS)-positive glycoprotein, leading to myocardial hypertrophy and diastolic dysfunction.

Cue-invariant activation in object-related areas of the human occipital lobe.

The extent to which primary visual cues such as motion or luminance are segregated in different cortical areas is a subject of controversy. To address this issue, we examined cortical activation in the human occipital lobe using functional magnetic resonance imaging (fMRI) while subjects performed a fixed visual task, object recognition, using three different primary visual cues: motion, texture, or luminance contrast. In the first experiment, a region located on the lateral aspect of the occipital lobe (LO complex) was preferentially activated in all 11 subjects both by luminance and motion-defined object silhouettes compared to full-field moving and stationary noise (ratios, 2.00+/-0.19 and 1.86+/-0.65, respectively). In the second experiment, all subjects showed enhanced activation in the LO complex to objects defined both by luminance and texture contrast compared to full-field texture patterns (ratios, 1.43+/-0.08 and 1.32+/-0.08, respectively). An additional smaller dorsal focus that exhibited convergence of object-related cues appeared to correspond to area V3a or a region slightly anterior to it. These results show convergence of visual cues in LO and provide strong evidence for its role in object processing.

A sequence of object-processing stages revealed by fMRI in the human occipital lobe.

Functional magnetic resonance imaging was used in combined functional selectivity and retinotopic mapping tests to reveal object-related visual areas in the human occipital lobe. Subjects were tested with right, left, up, or down hemivisual field stimuli which were composed of images of natural objects (faces, animals, man-made objects) or highly scrambled (1,024 elements) versions of the same images. In a similar fashion, the horizontal and vertical meridians were mapped to define the borders of these areas. Concurrently, the same cortical sites were tested for their sensitivity to image-scrambling by varying the number of scrambled picture fragments (from 16-1,024) while controlling for the Fourier power spectrum of the pictures and their order of presentation. Our results reveal a stagewise decrease in retinotopy and an increase in sensitivity to image-scrambling. Three main distinct foci were found in the human visual object recognition pathway (Ungerleider and Haxby [1994]: Curr Opin Neurobiol 4:157-165): 1) Retinotopic primary areas V1-3 did not exhibit significant reduction in activation to scrambled images. 2) Areas V4v (Sereno et al., [1995]: Science 268:889-893) and V3A (De Yoe et al., [1996]: Proc Natl Acad Sci USA 93:2382-2386; Tootell et al., [1997]: J Neurosci 71:7060-7078) manifested both retinotopy and decreased activation to highly scrambled images. 3) The essentially nonretinotopic lateral occipital complex (LO) (Malach et al., [1995]: Proc Natl Acad Sci USA 92:8135-8139; Tootell et al., [1996]: Trends Neurosci 19:481-489) exhibited the highest sensitivity to image scrambling, and appears to be homologous to macaque the infero-temporal (IT) cortex (Tanaka [1996]: Curr Opin Neurobiol 523-529). Breaking the images into 64, 256, or 1,024 randomly scrambled blocks reduced activation in LO voxels. However, many LO voxels remained significantly activated by mildly scrambled images (16 blocks). These results suggest the existence of object-fragment representation in LO.

The prevalence and perceived aetiology of male sexual problems in a non-clinical sample.

One hundred and nine men (38 per cent single, 48 per cent married) participated in a survey of the prevalence of erectile and ejaculatory difficulty in a non-clinical sample. Perceived aetiology of erectile difficulty was also investigated. Twenty-three per cent of the sample were currently experiencing sexual problems, with ejaculatory difficulty approximately three times as prevalent as erectile difficulty. Nearly one-quarter had experienced erection difficulties at some time and, of these, 68 per cent had remitted without formal treatment. Most frequently cited 'causes' of erectile difficulty were 'psychological' rather than 'physical', 'practical' or specifically 'sexual,' with relationship factors including communication between partners being perceived as particularly important. The presence of erectile and/or ejaculatory difficulty was related to sexual dissatisfaction but not to ratings of relationship happiness. Men having sexual relationships outside their permanent relationship found their partner less sexually attractive and rated themselves as less happy than those men not having affairs but the two groups did not differ in terms of presence of sexual difficulty or sexual dissatisfaction. The limitations of a sample biased towards younger, more educated men, are discussed.

Use of sedatives and hypnotics prescribed in a family practice.

The subsequent misuse and abuse of sedatives and hypnotics prescribed to 190 patients of the family practice program at the Medical University of South Carolina was investigated by medical record abstract and patient interviews. Results indicated little misuse and no abuse, with most respondents indicating they took fewer doses than directed. Concerns about dependence were widespread and were most likely in patients who said they never took fewer doses than directed. These patients were also more likely to have side effects. Ten percent of respondents said they had shared their sedative or hypnotic with others, usually relatives. Because of the nature of the population, mostly female and with an average age of 50 years, the results are likely to underrepresent misuse and abuse and to overrepresent concerns with dependence as compared with the general patient population. The results indicate the need for a prospective study to determine the process of becoming a misuser and factors associated with dependency fears.

Hospice care: perspectives on a Blue Cross Plan's community pilot program.

A community approach to the provision of hospice care utilizing existing community institutions in the metropolitan Washington, DC, area was started as a pilot project among three entities: the Washington Home, a licensed, skilled nursing facility, which served as the hospice inpatient unit; Georgetown University Hospital and its home care program, which were to serve as the sole referral sources; and Group Hospitalization, Inc., the local Blue Cross Plan. Insufficient referrals resulted in expansion of referral sources to include other hospice home care providers and acute care hospitals in the general community. As other community hospices developed, the Blue Cross Plan expanded the pilot program and fostered the communitywide coordination of hospice services.

Risk factors for fatal heart attack in young women.

Deaths of 338 women at ages 15-44 years attributed to myocardial infarction (MI) on death certificates during an 18-month period in five metropolitan areas were investigated. Evidence of recent MI or evidence that death occurred suddenly was obtained for about half (163) from records of hospitals or medical examiners or from relatives. A case-control study (involving one deceased control, and one hospitalized living control) of risk factors for heart attack was then conducted using interviews with relatives and abstracts of records of hospitals and physicians identified by the relatives as sources of medical care. Information was obtained on history of prior MI, other heart disease, diabetes, thromboembolism, stroke, hypertension, high cholesterol, obesity, oophorectomy, oral contraception and cigarette smoking. Data are presented on the prevalence of these potential risk factors for the case group and each control group, and for subsets of cases consisting of those without prior heart disease, definite MI only, sudden death only, and white women only. Multivariate analyses identify somewhat different sets of risk factors and different levels of risk for the various subgroups. In general, the risk factors are those that have been reported for men, despite the major difference in level of mortality.

PIP: An investigation was conducted of the deaths of 338 women (15-44 years of age) attributed to myocardial infarction (MI) on death certificates during an 18-month period in the metropolitan areas of New York City, Los Angeles, Chicago, Philadelphia, and Detroit. For 163 of the women evidence of recent MI or evidence that death occurred suddenly was obtained from records of hospitals or medical examiners or from relatives. A case-control study (involving 1 decreased control and 1 hospitalized living control) of risk factors for heart attack was then conducted. Interviews with relatives were used along with abstracts of records of hospitals and physicians identified by the relatives as sources of medical care. Information was obtained on history of prior MI, other heart disease, diabetes, thromboembolism, stroke, hypertension, high cholesterol, obesity, oophorectomy, oral contraception (OC), and cigarette smoking. Data are presented on the prevalence of these potential risk factors for the case group and each control group, and for subsets of cases consisting of those without prior heart disease, definite MI only, sudden death only, and white women only. Multivariate analyses identify somewhat different sets of risk factors and different levels of risk for the various subgroups. The prevalence of several factors--high cholesterol, obesity, diabetes, hypertension, and thromboembolism--was higher in the total group of cases than those without a history of MI or other heart disease. In general, the risk factors were those that have been reported for men, despite a major difference in level of mortality.

Georgetown University/Providence Hospital Family Practice Program, Washington, DC. Project test ways to coordinate medical, community services.

Fragmented medical care is especially harmful for chronically ill elderly patients. Intervention designed to educate them about their diseases and available resources may result in increased self-care and decreased rates of institutionalization.

Ambulatory care in the community.

To document the volume and kinds of ambulatory care, particularly primary care, being provided in a medically self-contained community, a survey was conducted in a county in a Middle Atlantic State during the summer of 1974 at all sites where physicians provided ambulatory care. These sites included not only physicians' offices, but also the emergency room, public health clinics, and physician-patient telephone encounters. Primary care was found to constitute 77 percent of all ambulatory care in the county and to account for 96 percent of all visits to primary care physicians. It also accounted for more than 50 percent of the visits to all physicians except the surgical subspecialists. Most of the primary care visits were for common disorders, common procedures, and common preventive measures. Distinct patterns were observed in the primary care morbidity treated by primary care physicians and that treated by specialists--patterns that seemed appropriate for those practices. The specialties of the physicians who were available to the population may have influenced morbidity patterns in the community surveyed. The primary care provided by primary care specialists appeared to differ in some functional aspects from that provided by other specialists.

Delegation potential of primary care visits by physician assistants, medex and primex.

In order to determine the appropriate level of any support for primary care new health practitioners (NHP) programs, an estimate needs to be made of the demand for these programs; the degree to which primary care NHPs can substitute for physicians' services will have an impact on this demand. Using community-wide data on the nature and volume of care provided by physicians in their ambulatory practices, the authors estimated the proportion of care that three common types of primary care NHPs could handle: Primex nurse practitioners, 2-year physician assistants and Medex. Panelists with expert knowledge of each NHP type assessed primary care abstracts to determine if the NHPs could have handled all, some or none of the visit. Overall, the three groups considered collectively were deemed capable of assuming all or some responsibility for a large proportion of primary care--92 per cent. Differences among NHP type were found with regard to the morbidity each could handle, with 2-year physician assistants capable of handling the broadest spectrum of care. Community-wide estimates made regarding the number of NHPs employable by physician specialty showed general practitioners and pediatricians having the practice volume and type of morbidity sufficient to most easily employ NHPs.

Fatal myocardial infarction and the role of oral contraceptives.

The association between use of oral contraceptives (OC) and death from myocardial infarction (MI) in young women was investigated in a collaborative case-control study conducted in the five largest metropolitan areas in the US. Potential cases were identified from computer tapes of the National Center for Health Statistics. Controls were selected from among women who died from, or were hospitalized for, acute conditions other than heart disease or from accidents, and were matched to cases on age, geographic area, and year of death. Information on cause of death, personal characteristics, OC use, and the presence of conditions predisposing to MI was obtained from interviews with relatives and abstracts of hospital, clinic and physician records. Odds ratios as approximations to relative risks for fatal MI in relation to OC use, and the associated 95% confidence limits, were calculated overall and for subgroups determined by demographic and health history characteristics. Odds ratios in the total study population were not significantly different from one. However, odds ratios significantly different from one were found when attention was restricted to white subjects without contraindications to OC use, andincluding only those cases whose deaths were attributed to MI with the greatest degree of certainty. Smoking was found to be a significant risk factor for fatal MI.

PIP: A collaborative case-control study was conducted in the 5 largest metropolitan areas in the United States in order to investigate the association between oral contraceptive (OC) use and death from myocardial infarction (MI) in young women. Potential cases were identified from computer tapes of the National Center for Health Statistics. The controls were selected from among women who died from, or were hospitalized for, acute conditions other than heart disease or from accidents; they were matched to cases on age, geographic area, and year of death. The population of study cases was defined to be all women, age 15-44, who died of an acute MI during the January 1974-June 1975 period. 163 cases were classified as either MI or sudden death (SD). Information regarding cause of death, personal characteristics, OC use, and the presence of conditions predisposing to MI was obtained from interviews with relatives and abstracts of hospital, clinic and physician records. Odds ratios as approximations to relative risks for fatal MI in relation to OC use, and the associated 95% confidence limits, were calculated overall and for subgroups determined by demographic and health history characteristics. Odds ratios in the total study population were not significantly different from 1, but odds ratios significantly different from 1 were found when attention was restricted to white subjects without contraindications to OC use, and including only those cases whose deaths were attributed to MI with the greatest risk of certainty. A signficant risk factor for fatal MI was smoking. The data suggest that use of OCs may increase the risk of death from MI.