High- but not low-dose folic acid improves endothelial function in coronary artery disease

BACKGROUND

While folic acid (FA) reduces plasma homocysteine (Hcy), whether the simultaneous improvement in endothelial function is dependent on Hcy lowering per se is questionable. In the present study the relationship between FA dose, Hcy lowering and endothelial function in patients with coronary artery disease (CAD) was investigated.

MATERIALS AND METHODS

Eighty-four patients with CAD received either 400 microg FA or 5 mg placebo daily for a 6-week treatment period. A further 44 patients with CAD received either 100 mg kg(-1) day(-1) of betaine or placebo for a 6-week treatment period. Flow-mediated dilatation (FMD), a measure of endothelial function, was assessed before and after the 6-week periods. Isometric tension and Western blotting were used to investigate the effect of FA on endothelial function and endothelial nitric oxide synthase (eNOS) dimerization in isolated rabbit aortic rings and cultured porcine aortic endothelial cells (PAEC), respectively.

RESULTS

Both 400 micro g day(-1) and 5 mg day(-1) FA significantly increased plasma folate and decreased plasma Hcy. The FMD improved significantly after 6 weeks' treatment of 5 mg day(-1) FA but did not correlate with the reduction in Hcy. There was no change in FMD in either the 400 micro g FA or placebo group. In a subgroup analysis of 11 patients in the betaine group, despite a reduced Hcy, a significant impairment in FMD was observed. In the in vitro studies FA, but not betaine, reversed methionine-induced endothelial dysfunction. Moreover, the FA promoted eNOS dimerization in cultured PAEC.

CONCLUSIONS

These data suggest that FA dose-dependently improves endothelial function in CAD via a mechanism independently of Hcy lowering. It may involve promotion of eNOS dimerization.

Estimating the abundance of eastern grey kangaroos (Macropus giganteus) in south-eastern New South Wales, Australia

To provide an estimate of kangaroo numbers for harvest management, a survey was designed for an area of 29 500 km2 encompassing the agricultural and grazing lands of the Braidwood, Cooma, Goulburn, Gundagai and Yass Rural Lands Protection Board (RLPB) districts in south-east New South Wales. An aerial survey using a helicopter was considered more efficient than ground survey because of the size of the area, relatively high relief and dense tree cover, and the need for regular monitoring. Tree cover and landscape relief was used to stratify the five RLPB districts into areas of probable high, medium and low kangaroo density. Kangaroo density estimated from helicopter surveys conducted in the Northern Tablelands of New South Wales was used to suggest densities and thereby allocate survey effort in each stratum. A survey comprising 735 km of transect line was conducted in winter 2003 with a target precision of 20%. The survey returned an estimate of 286 600 ± 32 300 eastern grey kangaroos for the whole of the proposed south-east New South Wales kangaroo-management zone. In 2004, a trial harvest of slightly less than 15% of this estimate was taken. Success of the trial will be determined by the impact of harvesting on the population’s dynamics, by landholder and industry participation, and by the capacity to monitor population size, harvest offtake and compliance with regulations.

Evaluation of an innovative approach to the Director of Public Health's annual report

BACKGROUND

The aim of this study was to evaluate the process of an innovative 'presentation with discussion' approach to the Director of Public Health's (DPH) annual report for North Derbyshire Health Authority.

STUDY DESIGN

Mixed methods-survey and interviews.

METHODS

Survey methods were used to obtain qualitative and quantitative data. Key stakeholders were sent a postal questionnaire, individuals attending presentations could respond via a printed slip or letter, structured group discussions following presentations were recorded manually, and presenters and producers were interviewed.

RESULTS

Thirty-five of 41 (85.4%) key stakeholders returned questionnaires, 18 people responded individually, discussions following 26/30 (86.7%) presentations were documented, and all eight presenters and 11 producers were interviewed. The general response was extremely positive with 25 of 35 (71%) key stakeholders, 100% of presenters and 80% of producers preferring the new format to the previous year's report. People felt that it conveyed the public health message effectively, and appreciated the opportunity to contribute to the recommendations for improving health in North Derbyshire. Many were concerned that the circulation should be wide, and key stakeholders were keen to have a printed reference document to support their work. Presenters enjoyed the process although tailoring the presentations to unfamiliar audiences proved difficult. The production team found the process more efficient and focused, although direct production costs were increased. Presenters and producers were concerned that the process for implementing recommendations for action was not fully considered.

CONCLUSIONS

Most people preferred this innovative approach to the traditional annual report, and it is therefore recommended that this format should be used for future DPH annual reports. Key stakeholders still require a reference document, and presenters' briefing notes could be adapted for this purpose. Circulation of the report should be wide, and further consideration of how participants' recommendations for action are implemented is needed.

Determinants of platelet responsiveness to nitric oxide in patients with chronic heart failure

Congestive heart failure (CHF) is associated with oxidative stress. Platelet responsiveness to nitric oxide (NO) donors, are impaired in patients with angina pectoris, possibly by increasing oxidative stress. We investigated the occurrence of platelet resistance to NO in patients, with ischaemic or non-ischaemic cardiomyopathy compared with normal subjects. Anti-aggregatory effects of sodium nitroprusside (SNP), oxidative stress and whole blood superoxide anion content were determined, with correlates of responsiveness to SNP. Inhibition of platelet aggregation by SNP was 65.4+/-3.55% in controls and 59.3+/-4.1% in CHF (P=ns) despite increased oxidative stress and post-aggregation O2- in CHF patients. However, subsets of CHF patients have NO-resistant platelets: this is associated with increasing age and/or increased oxidative stress (both p<0.05).

Non-invasive diagnosis of coronary artery disease by quantitative stress echocardiography: optimal diagnostic models using off-line tissue Doppler in the MYDISE study

AIMS

To develop optimal methods for the objective non-invasive diagnosis of coronary artery disease, using myocardial Doppler velocities during dobutamine stress echocardiography.

METHODS AND RESULTS

We acquired tissue Doppler digital data during dobutamine stress in 289 subjects, and measured myocardial responses by off-line analysis of 11 left ventricular segments. Diagnostic criteria developed by comparing 92 normal subjects with 48 patients with coronary disease were refined in a prospective series of 149 patients referred with chest pain. Optimal diagnostic accuracy was achieved by logistic regression models, using systolic velocities at maximal stress in 7 myocardial segments, adjusting for independent correlations directly with heart rate and inversely with age and female gender (all p<0.001). Best cut-points from receiver-operator curves diagnosed left anterior descending, circumflex and right coronary disease with sensitivities and specificities of 80% and 80%, 91% and 80%, and 93% and 82%, respectively. All models performed better than velocity cut-offs alone (p<0.001).

CONCLUSION

Non-invasive diagnosis of coronary artery disease by quantitative stress echocardiography is best performed using diagnostic models based on segmental velocities at peak stress and adjusting for heart rate, and gender or age.

Incidence of embolism and paravalvar leak after St Jude Silzone valve implantation: experience from the Cardiff Embolic Risk Factor Study

BACKGROUND

Silver coating of the sewing ring (Silzone) was introduced as a modification of the St Jude Medical standard valve to provide antibacterial protection, but the valve has recently been withdrawn.

OBJECTIVE

To study patients with these prostheses to assess possible adverse effects, and to guide their follow up.

DESIGN

Prospective observational study of risk factors for stroke after valve replacement.

SETTING

Cardiology and cardiac surgery departments in a tertiary centre.

PATIENTS

There were 51 patients with Silzone and 116 with St Jude Medical standard valves. Patients undergoing aortic valve replacement were well matched for stroke risk factors. Silzone patients with mitral valve replacement were younger (mean (SD) age 61 (10) v 66 (7) years), more likely to be female (95% v 65%), and had more pulmonary arterial hypertension (100% v 78%), but fewer coronary artery bypass grafts (5% v 33%) than patients with standard mitral valve replacements (all p < 0.05).

RESULTS

Follow up was 100% in the Silzone group (mean duration 3.0 (0.9) years) and 97.4% in the standard group (4.7 (1.4) years). Survival, morbidity, and anticoagulant control were documented over 682 follow up years (153 for Silzone and 529 for standard). There were six embolic strokes and one peripheral embolism in the Silzone group, all within three months after operation, and five embolic strokes and one peripheral embolism in the standard group. Freedom from major thromboembolism at three months was 65% in the Silzone mitral valve replacement group and 100% in the standard mitral valve replacement group (difference 35%, 95% confidence interval 8% to 62%). There was one reoperation for paravalvar leak in the standard group, but none in the Silzone group (NS). Anticoagulant control in the two groups was similar.

CONCLUSIONS

Patients with Silzone mitral valves had a high rate of early postoperative embolism but no excess paravalvar leak.

Feasibility and reproducibility of off-line tissue Doppler measurement of regional myocardial function during dobutamine stress echocardiography

AIMS

Off-line post-processing of colour tissue Doppler from digital loops may allow objective quantification of dobutamine stress echocardiography. We assessed the reproducibility of off-line measurements of regional myocardial velocities.

METHODS AND RESULTS

Nine observers analysed 10 studies, each making 2400 observations. Coefficients of variation in basal segments from apical windows, at rest and maximal stress, were 9-14% and 11-18% for peak systolic velocity, 16-18% and 17-19% for time-to-peak systolic velocity, 9-17% and 18-24% for systolic velocity time integral, and 18-23% and 21-27% for systolic acceleration. Coefficients of variation for diastolic velocities in basal segments at rest were 11-40%. Coefficients of variation for peak systolic velocity were 10-24% at rest and 14-28% at peak in mid segments, and 19-53% and 29-69% in apical segments. From parasternal windows coefficients of variation for peak systolic velocity were 14-16% in basal posterior, and 19-29% in mid-anterior segments. High variability makes measurement unreliable in apical and basal anterior septal segments. The feasibility of obtaining traces was tested in 92 subjects, and >90% in all basal and mid segments apart from the anterior septum.

CONCLUSION

Quantification of myocardial functional reserve by off-line analysis of colour tissue Doppler acquired during dobutamine stress is feasible and reproducible in 11 segments of the left ventricle. The most reliable measurements are systolic velocities of longitudinal motion in basal segments.

Flow-mediated dilatation following wrist and upper arm occlusion in humans: the contribution of nitric oxide

Flow-mediated dilatation (FMD) of the brachial artery assessed by high-resolution ultrasound is widely used to measure endothelial function. However, the technique is not standardized, with different groups using occlusion of either the wrist or the upper arm to induce increased blood flow. The validity of the test as a marker of endothelial function rests on the assumption that the dilatation observed is endothelium-dependent and mediated by nitric oxide (NO). We sought to compare the NO component of brachial artery dilatation observed following wrist or upper arm occlusion. Dilatation was assessed before and during intra-arterial infusion of the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) following occlusion of (i) the wrist (distal to ultrasound probe) and (ii) the upper arm (proximal to ultrasound probe) for 5 min in ten healthy males. Dilatation was significantly greater after upper arm occlusion (upper arm, 11.62+/-3.17%; wrist, 7.25+/-2.49%; P=0.003). During L-NMMA infusion, dilatation after wrist occlusion was abolished (from 7.25+/-2.49% to 0.16+/-2.24%; P<0.001), whereas dilatation after upper arm occlusion was only partially attenuated (from 11.62+/-3.17% to 7.51+/-2.34%; P=0.006). The peak flow stimulus was similar after wrist and upper arm occlusion. We conclude that dilatation following upper arm occlusion is greater than that observed after wrist occlusion, despite a similar peak flow stimulus. L-NMMA infusion revealed that FMD following wrist occlusion is mediated exclusively by NO, while dilatation following upper arm occlusion comprises a substantial component not mediated by NO, most probably related to tissue ischaemia around the brachial artery. FMD following wrist occlusion may be a more valid marker of endothelial function than dilatation following upper arm occlusion.

Does the use of a stentless bioprosthesis increase surgical risk?

Stentless aortic bioprostheses (SBPs) convey hemodynamic and perhaps survival benefit over stented counterparts. The aim of this study was to determine whether the more taxing operation increases surgical risk. We studied contemporary multicenter (USA) data submitted to the Food and Drug Administration (FDA) for Freestyle stentless (group I, n = 583) and Mosaic stented xenograft approval (group II, n = 1260). The study compared 30-day mortality for the two groups overall, then for isolated aortic valve replacement (AVR) and for AVR and coronary bypass (CABG). Because the USA Freestyle valves were used in selected patients (pts) we included SBP data (group III) from Oxford, where Freestyle valves were used consecutively within the same time frame. We also reviewed hospital mortality in the stentless bioprosthesis literature and compared this with the Society of Thoracic Surgery Database. There were no differences in age, NYHA, or incidence of CABG between the groups. There was no significant difference in operative mortality between stented (group II) and exclusive (group III) SBP patient groups (P =.233 for AVR and P =.478 for AVR + CABG), or between selective (group I) and exclusive (P =.929 for AVR and P =.390 for AVR + CABG) groups, after adjustment for risk factors. However, there was a significantly higher mortality both for isolated AVR (P =.026) and AVR + CABG (P =.001) in the selected stentless group compared with stented. This was partly attributed to greater mortality when the Freestyle was used in elderly patients by the full root replacement method, and to the higher proportion of females, and subjects with intra-aortic balloon pump insertion in this group. A meta-analysis of published stentless valve series, showed mortality rates to be lower than those of the STS National Database average. During the learning curve selective use of SBPs increased hospital mortality for AVR +/- CABG. Consecutive use dispelled the difference and the literature now suggests that SBPs may reduce hospital mortality for high-risk patients.

Cardiac performance in endurance-trained and moderately active young women

PURPOSE

To compare the cardiac performance of endurance-trained (ET) and moderately active (MA) young women before exercise and throughout incremental work rates to maximum with particular interest in whether their stroke volume (SV) levels off at a submaximal work rate or increases to maximum.

METHODS

Blood volume (BV), and exercise cardiac performance were examined in seven ET (VO2max = 64.3 +/- 2.0 mL.kg(-1).min(-1)) and seven MA (VO2max = 42.1 +/- 1.0 mL.kg(-1).min(-1)) women, aged 18-30 yr. Cardiac time intervals were measured at matched heart rates (HR).

RESULTS

ET had a significantly larger BV than MA in both mL (ET = 5053 +/- 139, MA = 4327 +/- 202) and mL.kg(-1) (ET = 83.1 +/- 1.4, MA = 72.9 +/- 2.7). The SV of ET was significantly larger than the SV of MA throughout exercise, and the SV of ET increased progressively throughout incremental work rates to maximum. Although the SV of MA initially leveled off at a submaximal work rate, it underwent a secondary increase at very heavy work rates. Both diastolic filling rate (DFR) and left ventricular emptying rate (LVER) were significantly faster in ET compared with MA at HR of 150 bpm, 170 bpm and HRmax, and in both ET and MA, DFR was significantly faster than LVER at 170 bpm and HRmax.

CONCLUSIONS

In young women, ET have a larger SV than MA due to an enhanced DFR and LVER, with the primary advantage being DFR (possibly due to their larger BV). In addition, the SV of ET increases progressively throughout incremental work rates to maximum with no plateau, whereas the SV of MA levels off through moderate to heavy work rates then undergoes a secondary increase at very heavy work rates.

Twenty years' experience with the Medtronic Hall valve

OBJECTIVE

To assess the performance of the Medtronic Hall valve (Medtronic, Inc, Minneapolis, Minn) in one institution over a 20-year period.

METHODS

Since 1979, Medtronic Hall valves have been used in 1766 procedures (736 aortic, 796 mitral, and 234 double). Patients were followed up prospectively at 6- to 12-month intervals for a total of 12,688 follow-up years. Anticoagulation data (international normalized ratio) were recorded for all patients (approximately 95,000 observations).

RESULTS

Linearized rates of valve-related late death for aortic, mitral, and double valve replacement were 0.8%/y, 0.9%/y, and 1.1%/y, respectively. Risk factors for late mortality were (relative risk) diabetes (1.9), decade of age (1.6), concomitant coronary artery bypass grafting (1.4), hypertension (1.3), non-sinus rhythm (1.3), large valve size (1.1), valve regurgitation (1.3), and male sex (1.2). For aortic, mitral, and double valve replacement, linearized rates (percent per year) of adverse events were valve thrombosis 0.04, 0.03, and 0.0; all thromboembolism 2.3, 4.0, and 3.4; stroke 0.6, 0.8, and 0.6; major hemorrhage 1.2, 1.4, and 1.6; and prosthetic endocarditis 0.4, 0.4, and 0.7. Risk factors for thromboembolism were (relative risk) mitral valve replacement (1.9), diabetes (1.8), hypertension (1.5), and history of embolism (1.4).

CONCLUSION

At 20 years the Medtronic Hall valve demonstrates excellent durability, good hemodynamic performance, and very low thrombogenicity, with a valve thrombosis rate lower than those reported for bileaflet designs. With this prosthesis, both survival and thromboembolic events are predominantly determined by patient risk factors.

Subclinical right ventricular dysfunction in cystic fibrosis. A study using tissue Doppler echocardiography

Patients with severe cystic fibrosis can develop cor pulmonale, but little is known about the function of the right ventricle (RV) early in the disease. We hypothesized that such patients might have subclinical RV dysfunction, detectable by tissue Doppler echocardiography, and related to the severity of lung disease. We studied 21 clinically stable patients (Group 1), five patients with severe lung disease (Group 2), and 23 age-matched healthy subjects. Patients had impaired RV systolic function. The mean (SD) systolic velocities of the RV free wall were 8.9 (1.7) cm/s in Group 1, 7.7 (1.0) in Group 2, and 10.8 (1.9) in healthy subjects (p < 0.001). The velocities of the tricuspid annulus were less in patients (p < 0.0001). Patients had a greater isovolumic relaxation time (p < 0.001), indicating RV diastolic dysfunction. RV wall thickness was greater in patients (0.4 [0.1] versus 0.3 [0.1] cm/m(2), p < 0.01). RV systolic function was related to C-reactive protein (r = - 0.66, p < 0.001) and FEV(1) (r = 0.62, p = 0.003) and diastolic function to interleukin-6 (r = 0.64, p < 0.005). Patients with cystic fibrosis have subclinical RV dysfunction, which correlates with the severity of lung disease. Tissue Doppler echocardiography provides a quantifiable indicator useful for detection and monitoring of disease progression.

Occupational stressors and coping as determinants of burnout in female hospice nurses

AIMS

Stressors, coping and demographic variables were examined as predictors of burnout in a sample of hospice nurses. The study aimed to investigate the level of burnout among hospice nurses; to ascertain which aspects of nursing work were positively or negatively related to burnout; to examine the relative contributions made by these different variables and to suggest individual and organizational interventions to reduce levels of burnout.

METHODS

Eighty-nine female nurses from nine hospices completed a battery of questionnaires comprising the Maslach Burnout Inventory, Nursing Stress Scale, Ways of Coping Scale and a demographic information form.

RESULTS

In general, the level of burnout (characterized by high emotional exhaustion, high depersonalization of patients and low personal accomplishment) was found to be low. In multiple regression analyses, 'death and dying', "conflict with staff', 'accepting responsibility' and higher nursing grade contributed to emotional exhaustion. 'Conflict with staff', 'inadequate preparation', 'escape' and reduced 'planful problem-solving' contributed to depersonalization. 'Inadequate preparation', 'escape', reduced 'positive reappraisal' and fewer professional qualifications contributed to lower levels of personal accomplishment. Overall, stressors made the greatest contribution to burnout and demographic factors contributed the least.

CONCLUSIONS

The importance of not labelling individuals as good and bad 'copers' was discussed, as the effectiveness of a strategy may depend on the situation. It was concluded that the investigation of problem-focused and emotion-focused coping in relation to burnout, was oversimplifying the coping-burnout relationship. Suggestions for stress management included staff training in counselling skills, monitoring staff conflict, implementing stress inoculation training to teach appropriate use of coping skills and finally, monitoring particularly vulnerable groups of hospice staff such as unqualified nursing assistants and qualified nurses in management positions. It was concluded that despite the difficult nature of hospice work, the hospice is a positive environment in which to work.

Canadian musculoskeletal fitness norms

The purpose of this report is to provide representative norms for measurements of musculoskeletal fitness (partial curl-ups, vertical jump, and leg power) for which Canadian norms are not currently available. Partial curl-ups, vertical jump, trunk flexion (sit and reach), grip strength, muscular endurance (push-ups), body mass index, and subcutaneous adiposity (sum of five skinfolds) were assessed, and leg power was calculated in 571 self-reportedly healthy participants (312 females and 259 males) aged 15-69 yr. The representativeness of the sample was confirmed by statistically comparing the fitness characteristics of the participants in the present study to those in the Canada Fitness Survey of 1981 and the Campbell's Survey of 1988. Normative data for partial curl-ups, vertical jump, and leg power were generated for males and females in six age groups (15-19, 20-29, 30-39, 40-49, 50-59, 60-69) for use in fitness appraisal protocols for the Canadian population.

What common disorders do those reporting limiting long-term illness experience, and what is their survival and health service utilization experience?

BACKGROUND

The aim of this study was to examine the relationships between self-reported limiting long-term illness and other disease-specific symptoms, mortality and use of hospital services.

METHODS

A cohort generated by population health survey was linked to information on mortality and health service use, in Sheffield, England, 1994-1998. Limiting long-term illness was assessed using the 1991 Census question wording; specific symptoms were assessed using standard instruments; other outcomes were admission to hospital and mortality.

RESULTS

Limiting long-term illness is stated more commonly than in the Census, especially in males and in the young. It is commoner in the presence of some conditions such as angina much more than in others such as gastrointestinal disease. For all age groups, both mortality and, to a lesser extent, hospital admission rates are higher in those responding yes to the long-term illness question.

CONCLUSIONS

Limiting long-term illness assessment from the Census acts as a better proxy for some aspects of population health than others although it may underestimate the absolute prevalence. Although it may be of use in identifying relative needs, mortality is associated more strongly with differences in limiting long-term illness than is health service utilization. This may be as much a result of mismatch between use and need as of any deficiency of the measure itself.