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Biomedical subjects

D Hunter

Publications and source records attributed to D Hunter.

At least 127 records · Page 7Linked to original sources
PubMed1993

Prediction of cardiovascular death in men undergoing noninvasive evaluation for coronary artery disease.

OBJECTIVE: To develop prediction rules from clinical and exercise test data identifying patients at high and low risk for cardiovascular events among a group of male veterans. DESIGN: Prognostic study with prospective gathering of data and routine follow-up of consecutive patients referred for exercise testing. Patients only underwent noninvasive evaluation for coronary artery disease. No validation cohort is yet available. SETTING: A 1200-bed Veterans Affairs Medical Center. PATIENTS: Of 3609 men referred for exercise testing between 1984 and 1990, 2546 patients remained evaluable after exclusion of those who underwent subsequent cardiac catheterization, those with significant valvular heart disease, and those who had previous coronary artery bypass surgery. MEASUREMENTS: Evaluation included recording of clinical data on a standardized form and a standard treadmill test followed by assessment of cardiovascular events. RESULTS: During a mean follow-up period (+/- SD) of 2.75 (+/- 18) years, 119 cardiovascular deaths and 44 nonfatal myocardial infarctions occurred in 2546 patients. The Cox proportional hazards model showed the following characteristics to be statistically independent predictors of time until cardiovascular death: history of congestive heart failure or digoxin use, exercise-induced ST depression, change in systolic blood pressure during exercise, and exercise capacity. Using a simple score based on one item of clinical information (history of congestive heart failure or digoxin use) and three exercise test responses (ST depression, exercise capacity, and change in systolic blood pressure), 77% of patients were categorized as low risk (annual cardiac mortality rate, less than 2%), 18% as moderate risk (annual cardiac mortality rate, 7%), and 6% as high risk (annual cardiac mortality rate, 15%; hazard ratio, 10; 95% confidence interval, 6 to 17). This model has not yet been validated. CONCLUSIONS: Variables available from the usual non-invasive work-up of patients with known or suspected coronary artery disease can be used to predict future risk for cardiovascular death.

Aged↗
PubMed1993

Sound bites.

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Consumer Behavior↗
PubMed1993

Prediction of cardiovascular death by means of clinical and exercise test variables in patients selected for cardiac catheterization.

The objective of this report is the development of a population-specific prediction rule based on clinical and exercise test data that would estimate the risk of cardiovascular death in patients selected for cardiac catheterization. Prospective data and follow-up information were obtained from patients who underwent cardiac catheterization soon after clinical assessment and exercise testing. Males (n = 588) referred for evaluation of coronary heart disease from 1984 to 1990 were selected after exclusion of patients with significant valvular heart disease and patients with prior cardiac surgery. Half had a prior myocardial infarction and half complained of typical angina pectoris. All patients performed a treadmill test and were selected for clinical reasons to undergo coronary angiography within 3 months. Over a mean follow-up period of 2.5 years (+/- 1.4 years), there were 39 cardiovascular deaths and 45 nonfatal myocardial infarctions. The Cox proportional hazards model demonstrated the following characteristics to be statistically significant independent predictors of time until cardiovascular death: history of congestive heart failure (hazards ratio of 4), ST depression on the resting ECG (hazards ratio of 3), and a drop in systolic blood pressure below the resting value during exercise (hazards ratio of 5). Exercise-induced ST depression was not associated with either death or nonfatal myocardial infarction. A simple score based on one item of clinical information (history of congestive heart failure), a resting ECG finding (ST depression), and an exercise test response (exertional hypotension) stratified our patients for 4 years after testing from 75% with a low risk (annual cardiac mortality rate of 1%), 17% with a moderate risk (annual mortality rate of 7%), and 1% with a high risk (annual cardiac mortality rate of 12%, with a hazards ratio of 20 and 95% confidence interval from 6 to 70X). It was concluded that the variables available from the usual noninvasive workup of patients with known or suspected coronary artery disease enable prediction of risk of cardiovascular death. Three quarters of those usually undergoing cardiac catheterization can be identified by simple noninvasive variables as being at such low risk that invasive intervention is unlikely to improve prognosis.

Aged↗
PubMed1993

Long-term oral nitrate therapy prevents chronic ventricular remodeling in the dog.

OBJECTIVES: The purpose of this experiment was to assess the long-term effects of oral nitrate therapy on ventricular remodeling in a canine model of discrete myocardial damage. BACKGROUND: A progressive increase in left ventricular mass and volume has been documented after experimental and clinical myocardial infarction. This ventricular remodeling has been associated with the development of congestive heart failure. Nitrate therapy, especially when combined with hydralazine, is effective in the management of clinical heart failure. Moreover, nitrates inhibit infarct expansion, one of the earliest manifestations of ventricular remodeling. Whether nitrates can attenuate chronic left ventricular remodeling is unknown. METHODS: Dogs with discrete myocardial necrosis produced 24 h earlier by transmyocardial direct current shock were randomized to receive isosorbide mononitrate, 30 mg twice daily (n = 10), or no treatment (n = 4); the latter group was augmented by 13 control dogs from a prior study in which an identical protocol was used. Ventricular structure was assessed with nuclear magnetic resonance imaging at baseline and at 1 and 16 weeks after myocardial damage. RESULTS: Left ventricular mass increased at 1 week in the control group (mean +/- SD 68.1 +/- 10.7 g to 80.1 +/- 12.1 g, p = 0.0001) but not in the nitrate-treated group (70.2 +/- 7.7 g to 69.6 +/- 7.3 g, p = NS). No change in left ventricular volume was observed in either group during the 1st week after myocardial damage. After 16 weeks of follow-up left ventricular mass had increased by 12.7 +/- 7.1 g (p = 0.001) in the control group and had decreased by 1.2 +/- 7.7 g in the nitrate group. Left ventricular volume was increased at 16 weeks by 14.2 +/- 10.3 ml in the control group but was decreased by 3.7 +/- 7.5 ml in the nitrate group. Isosorbide mononitrate produced transient hemodynamic effects with a return of most measured variables toward baseline within 2 h after administration of the drug. At 1 week there was no intergroup difference in rest hemodynamic variables assessed 12 h after drug administration. At 16 weeks, pulmonary capillary wedge pressure (15 +/- 4 vs. 8 +/- 3 mm Hg, p = 0.0001), pulmonary artery pressure (24 +/- 5 vs. 16 +/- 3 mm Hg, p = 0.0001) and right atrial pressure (10 +/- 3 vs. 6 +/- 3 mm Hg, p = 0.008) were all higher in the control group. CONCLUSIONS: Long-term oral nitrate therapy attenuates the early and late manifestations of ventricular remodeling after myocardial damage in the dog. Hemodynamic observations suggest the possibility that drug-induced preload or afterload reduction does not completely explain this effect.

Administration, Oral↗
PubMed1993

Day surgery: development of a national comparative audit service.

OBJECTIVES: To develop software for hospitals to analyse their own survey data on patients' experiences of day surgery and to create and test the feasibility of a national comparative audit service. DESIGN: Software development and testing; database analysis. SETTING: Eleven general hospitals in England. PATIENTS: 1741 day surgery patients undergoing procedures during 1991-2. MAIN MEASURES: Postoperative symptoms, complications, health and functional status, general satisfaction, and satisfaction with specific aspects of care. RESULTS: Software for data entry and analysis by hospitals was successfully used at the pilot sites. The overall response rate for the 11 hospitals using the questionnaire was 60%, ranging from 33% to 90% depending on the way the survey was managed. Data from all 11 hospitals were included in the national comparative audit database. Hospitals showed little variation in measures of patients' overall satisfaction (around 85%), but significant differences were apparent for specific aspects such as receiving adequate written information before admission (range 50%-89%), provision of adequate parking facilities (14%-92%) and experiencing a significant amount of postoperative pain (8%-42%). The proportion of day case patients undergoing procedures that could have been performed in outpatient departments varied from 0 to 27% between hospitals. Further comparisons of outcome, in particular measures of effectiveness, must await the development of validated case mix adjustment methods. CONCLUSION: Establishing a comparative audit database is feasible but several methodological problems remain to be resolved.

Ambulatory Surgical Procedures↗
PubMed1992

Forward march.

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Public Health Administration↗
PubMed1992

Here we go again.

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Community Participation↗
PubMed1992

Correlation of coronary with peripheral arterial stenosis. The POSCH Group.

Although it is known that patients with peripheral arterial disease are at high risk for coronary arterial stenosis, it is not known if, conversely, coronary artery disease correlates with peripheral arterial stenosis. In the Program on Surgical Control of the Hyperlipidemias (POSCH) coronary and aortic-iliac-femoral arteriograms were systematically analyzed. POSCH is a randomised, controlled secondary intervention clinical trial of hyperlipidemic subjects, ages 30-64 years with one myocardial infarction and angiographically demonstrable coronary arterial stenosis. Of the 838 subjects enrolled in the study, 436 had diagnostic visualization of both the coronary and aortic-iliac-femoral systems. The aortic-iliac-femoral arteries were normal in 44% (194/436) of the subjects. In contrast, only 9% (37/436) of the subjects had less than 50% stenosis of all 3 coronary arteries. However, there was a positive correlation between the severity of the stenosis, if present, in the aortic-iliac-femoral arteries and that in the coronary arteries (P less than 0.001). The subjects who did exhibit aortic-iliac-femoral arterial disease were significantly older and more frequently were cigarette smokers. We conclude that subjects with coronary arterial stenosis frequently are free of peripheral arterial disease.

Adult↗
PubMed1992

An assessment of regeneration across peripheral nerve allografts in rats receiving short courses of cyclosporin A immunosuppression.

While peripheral nerve reconstruction could benefit from the use of nerve allografts, long term immunosuppression for non-vital organ transplantation is controversial. This study investigated the effectiveness of short course Cyclosporin A immunosuppression. Fourteen Lewis (RT1l) rats were the recipients of 3 cm sciatic nerve grafts from ACI (RT1a) donors, repaired to the transected sciatic nerve of the recipient animal. Animals were treated with Cyclosporin A (5 mg/kg/day) for eight weeks. Neuromuscular function was assessed every two weeks by sciatic function index determinations until 20 weeks. Electrophysiological, histological and morphological evaluations were performed at 14 (n = 6) and 20 weeks (n = 8) postengraftment. Rats had significantly improving functional studies from four to eight weeks (P = 0.01). Function decreased following cessation of Cyclosporin A treatment. Rats evaluated at 14 weeks had histological evidence of graft rejection with inflammatory cell infiltration, extensive demyelination and remyelination, and some Wallerian degeneration. Rats demonstrated improvement in morphological parameters and motor function from 14 to 20 weeks after engraftment. In this sciatic nerve allograft model, short course Cyclosporin A immunosuppression, although resulting in an initial episode of graft rejection, was successful in permitting good long term functional regeneration of neuromuscular function.

Animals↗
PubMed1992

Rapid, accurate and simultaneous noninvasive assessment of right and left ventricular mass with nuclear magnetic resonance imaging using the snapshot gradient method.

Left ventricular, and possibly also right ventricular, mass is an important determinant of prognosis in cardiovascular disease. Consequently, noninvasive estimation of ventricular mass may be an important clinical investigation. The ideal technique for this purpose would be widely available and accurate, employ short study times and avoid exposure to contrast agents and radiation. Conventional nuclear magnetic resonance (NMR) imaging fulfills most of these criteria, but it is time-consuming and expensive. Moreover, its accuracy in estimating right ventricular mass has yet to be assessed. Accordingly, high speed NMR imaging using the snapshot gradient echo technique was used to assess right and left ventricular mass in 10 dogs and the results were compared with values obtained at autopsy, which ranged from 26.1 to 52.9 and 61 to 119.8 g, respectively. The mean absolute difference between the NMR imaging estimates and autopsy findings was 2 +/- 1.2 g (range 0.4 to 4.2) for right ventricular mass and 4.4 +/- 1.7 g (range 1.8 to 6.6) for left ventricular mass. Total NMR imaging time was less than or equal to 5 min. These data demonstrate that high speed NMR imaging can be used to accurately estimate right as well as left ventricular mass.

Animals↗
PubMed1992

Hypoxaemia and pain relief after lower abdominal surgery: comparison of extradural and patient-controlled analgesia.

We have examined postoperative pain in patients allocated randomly to receive extradural bolus diamorphine 3.6 mg, extradural infusion of 0.15% bupivacaine with 0.01% diamorphine or patient-controlled i.v. administration of diamorphine at a maximum rate of 1 mg per 5 min, after total abdominal hysterectomy. Extradural infusion analgesia produced the smallest pain scores from 12 to 24 h after surgery (P < 0.05). More patients in the extradural infusion group were moderately hypoxaemic (SpO2 < 90% > 12 min h-1) after operation, compared with the two other groups (P < 0.05). The group using patient-controlled analgesia received more diamorphine and suffered a greater incidence of emetic sequelae (P < 0.05).

Abdomen↗
PubMed1992

Hypoxaemia and pain relief after upper abdominal surgery: comparison of i.m. and patient-controlled analgesia.

Forty patients recovering from upper abdominal surgery were allocated randomly to receive i.m. morphine 0.15 mg kg-1 as required or patient-controlled analgesia (PCA), with i.v. morphine 1 mg and a 5-min lock out time. Arterial oxygen saturation (SpO2) was measured continuously the night before and for 24 h immediately after surgery. A significantly greater proportion of patients in the PCA group (nine of 19) rated their analgesia as excellent compared with the i.m. group (two of 20) (P < 0.05). There was no significant difference in the incidence of postoperative hypoxaemia in the two treatment groups. Severe postoperative hypoxaemia (SpO2 < 85% for more than 6 min h-1) was seen in three patients receiving i.m. analgesia and one patient in the PCA group.

Abdomen↗
PubMed1992

The peripheral nerve allograft in the primate immunosuppressed with Cyclosporin A: I. Histologic and electrophysiologic assessment.

Nerve regeneration across peripheral nerve allografts and control autografts in primates immunosuppressed with Cyclosporin A was quantitatively evaluated by electrophysiologic and histologic methods. Twelve cynomolgus monkeys received 3-cm autografts and allografts in contralateral ulnar nerves. They were immunosuppressed with Cyclosporin A at 25 mg/kg per day or placebo vehicle. Morphometric analysis of nerve graft and distal nerve segments was assessed at 1 year after engraftment. Quantitative electrophysiologic studies were performed percutaneously at 6 and 12 months, and compound action potentials were measured directly across the nerve grafts at 1 year. Excellent regeneration was seen across autografts and allografts in Cyclosporin A-treated and placebo-treated recipients.

Action Potentials↗
PubMed1992

Chlamydia trachomatis and oral contraceptive use: a quantitative review.

OBJECTIVES: Chlamydia trachomatis is now recognised as a major sexually transmitted disease; oral contraceptive use is rapidly increasing particularly in developing countries. There are thus important public health implications of the many reports that isolation of C trachomatis is more frequent among users of oral contraceptives. The aim of this analysis was to assess the strength and consistency of this association by summarising published studies between 1972 and 1990. DESIGN: Studies identified were grouped according to whether they were prospective or case-control studies. Data were extracted and pooled estimates of the unadjusted odds ratios were made for all studies, as well as for sub-groups defined by an index of study quality, background prevalence of C trachomatis, and the contraceptive comparison being made. LOCATION: Studies in the analysis were mainly conducted in Europe and North America; the meta-analysis was done at the Harvard School of Public Health, Boston, MA, USA. RESULTS: The pooled estimated unadjusted odds ratio for 29 case-control studies examined was 1.93 (95% CI, 1.77-2.11), indicating an almost twofold increased risk of chlamydial infection for oral contraceptive users. Neither study quality nor prevalence of C trachomatis modified this risk. When compared to the use of barrier contraceptives, however, the risk of infection for women using oral contraceptives increased to 2.91 (95% CI, 1.86-4.55). The pooled estimated protective effect of barrier methods in these studies was 0.34 (95% CI, 0.22-0.54). CONCLUSIONS: Cross-study comparisons of the relationship between oral contraceptive use and chlamydial infection are limited by the design and analysis of many component studies which did not control for confounding factors such as sexual behaviour and age. The almost twofold risk of increased chlamydial infection for oral contraceptive users, supported by the findings of two prospective studies, however, points to the importance of considering the risks and benefits of oral contraceptive use in women who are likely to be exposed to C trachomatis and other STDs. The protective effect of barrier methods emphasizes the continued need for promoting barrier methods of contraception.

Case-Control Studies↗