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Biomedical subjects

Nicola Payne

Publications and source records attributed to Nicola Payne.

18 recordsLinked to original sources
PubMed2006

Increased sensitivity to warfarin after heart valve replacement.

BACKGROUND: The dosage requirement of warfarin to achieve a given international normalized ratio (INR) often varies considerably between the immediate postoperative period and long-term follow-up in patients with prosthetic heart valves, leading to INR instability. OBJECTIVE: To document the extent of warfarin sensitivity in a prospective study of patients receiving heart valve replacements. METHODS: Clinical and laboratory data regarding anticoagulation for 111 patients who received warfarin following heart valve replacement were collected during their hospital stay (induction period) and between 1 and 3 months after surgery (follow-up period). RESULTS: Mean patient age was 65.39 +/- 10.55 years (range 29-85), with 66 men. The mean INR value during the follow-up period was, on average, 0.21 higher than the induction period (2.81 +/- 0.5 vs 2.6 +/- 0.6; p = 0.007). The mean follow-up warfarin dose was 1.54 mg higher than the mean induction warfarin dose (5.09 +/- 2.03 vs 3.55 +/- 1.94 mg; p < 0.001). The warfarin dose index, which indicates relative sensitivity of warfarin, decreased from 1.16 to 0.65 (p < 0.001). Although the INR values during the induction and follow-up periods were similar, the dose requirement in the follow-up period was, on average, 43% higher than that of the induction period. CONCLUSIONS: Immediately after heart valve replacement, patients are more sensitive to warfarin and should receive a lower warfarin dose during the initial phase of oral anticoagulation treatment. This enhanced sensitivity decreases with time. Patients require frequent monitoring and are likely to need an increase in the warfarin dose to avoid insufficient anticoagulation during the early follow-up period.

Adult↗
PubMed2005

Regional response of myocardial acceleration during isovolumic contraction during dobutamine stress echocardiography: a color tissue Doppler study and comparison with angiocardiographic findings.

BACKGROUND: Color tissue Doppler imaging permits noninvasive quantitation of regional wall motion. In experimental studies, a new marker, the slope of the isovolumic contraction wave, isovolumic acceleration (IVA) was more insensitive to ventricular loading conditions than myocardial velocities. This study compared the regional response IVA to dobutamine stress echocardiography to angiographic findings. METHODS: The Myocardial Doppler in Stress Echocardiography (MYDISE) study prospectively recruited 149 consecutive patients with chest pain for dobutamine stress tissue Doppler echocardiography prior to coronary angiography. This color tissue Doppler database was analyzed for IVA in 1,192 basal and mid segments at rest and again at peak stress. Angiographic findings were compared to IVA and peak systolic velocities (PSV) in corresponding cardiac segments. The diagnostic accuracy of IVA to predict coronary artery stenosis was determined using cut-off values for three representative segments and with the MYDISE diagnostic model including eight segments. RESULTS: Regional IVA increased in a dose-dependent manner during dobutamine infusion. The response was blunted in the supply territory of stenosed coronary artery branches. IVA performed slightly better than PSV as single marker for coronary artery stenosis. A diagnostic model incorporating IVA and PSV was 85-95% accurate (area under receiver operating characterstic curves). CONCLUSIONS: Regional changes of isovolumic acceleration during dobutamine stress echocardiography reflect regional wall motion and can be used to predict coronary artery stenosis with similar accuracy as a model based on systolic myocardial velocities. As a single marker, IVA performed better than myocardial velocities.

Acceleration↗
PubMed2005

The impact of job strain on the predictive validity of the theory of planned behaviour: an investigation of exercise and healthy eating.

OBJECTIVES: This study examined the impact of the job strain model on exercise and healthy eating within the framework of the Theory of Planned Behaviour. DESIGN: Participants completed a questionnaire measuring the components of the Theory of Planned Behaviour and the job strain model. A follow-up questionnaire a week later measured behaviour. METHOD: The questionnaires were completed by e-mail. The initial questionnaire was completed by 331 employees, and 286 follow-up questionnaires were returned. RESULTS: Job demands affected exercise indirectly by lowering perceptions of behavioural control over exercise. However, variables from the job strain model were not related to exercise intentions or behaviour. In contrast, employees in passive jobs intended to eat more sweets and snack foods and employees in low strain jobs were more likely to realize their intentions to eat more sweets and snack foods. However, variables from the job strain model did not influence consumption of fruit and vegetables. CONCLUSIONS: While people may consider the impact of job strain on exercise whilst making decisions about whether or not to exercise, job strain has a more direct impact on healthy eating. However, job strain may only affect consumption of so-called 'high density' foods, rather than foods such as fruit and vegetables.

Adult↗
PubMed2004

Effects of exogenous and endogenous natriuretic peptides on forearm vascular function in chronic heart failure.

OBJECTIVE: Natriuretic peptides (NPs) reduce central venous pressure in patients with chronic heart failure (cHF) despite attenuation of arterial, renal, and humoral effects. This suggests a preserved venodilator response. This study had 4 aims: to compare the venodilator effects of human NPs in patients with cHF; to assess the contribution of basal ANP and BNP levels to regulation of forearm vascular volume (FVV); to test the hypothesis that venous ANP responsiveness is preserved in cHF; and to assess the involvement of endothelial nitric oxide-synthase (eNOS) in NP-induced vascular effects. METHODS AND RESULTS: Venous and arterial forearm vascular responses to incremental intra-arterial doses of ANP, Urodilatin, BNP, CNP, or the ANP receptor antagonist A71915 were studied in 53 patients and 11 controls. ANP receptor antagonism reduced FVV by 4.4%+/-1.2% (P<0.05). The forearm blood flow (FBF) response to ANP was significantly blunted in patients versus controls (P<0.01), whereas FVV increased similarly in both groups (maximum 14.7% and 13.4%, both P<0.001). The eNOS blockade reduced ANP-induced FBF changes in controls but not in patients (P<0.05), whereas similar reductions in FVV changes were seen in groups (both P<0.001). CONCLUSIONS: In cHF venous, but not arterial, ANP responsiveness is preserved. Arterial endothelial dysfunction may contribute to NP resistance.

Adult↗
PubMed2004

Impact of educational mailing on the blood pressure of primary care patients with mild hypertension.

OBJECTIVE: To assess the effectiveness of mailed hypertension educational materials. DESIGN: Prospective, randomized, controlled single-blind trial. SETTING: Primary care practice-based research network in which 9 clinics located in Portland, Oregon participated. PARTICIPANTS: Patients with mildly uncontrolled hypertension as defined as a last blood pressure of 140 to 159/90 to 99 mmHg from query of an electronic medical record database. INTERVENTIONS: Patients randomized to intervention were mailed 2 educational packets approximately 3 months apart. The first mailer included a letter from each patient's primary care provider. The mailer included a booklet providing an overview of hypertension and lifestyle modification and a refrigerator magnet noting target blood pressure. The second mailing also included a letter from the patient's primary care provider, a second educational booklet focused on medication compliance and home blood pressure monitoring, and a blood pressure logbook. The control group consisted of similar patients receiving usual care for hypertension. MEASUREMENTS AND MAIN RESULTS: Patients from each group were randomly selected for invitation to participate in a study visit to measure blood pressure and complete a survey (intervention n= 162; control n= 150). No significant difference was found in mean blood pressure between intervention and control patients (135/77 mmHg vs 137/77 mmHg; P=.229). Patients in the intervention arm scored higher on a hypertension knowledge quiz (7.48 +/- 1.6 vs 7.06 +/- 1.6; P=.019), and reported higher satisfaction with several aspects of their care. No significant difference was seen in the prevalence of home blood pressure monitoring ownership or use. CONCLUSIONS: In patients with mildly uncontrolled hypertension, educational mailers did not yield a significant decrease in blood pressure. However, significant improvement in patient knowledge, frequency of home monitoring, and satisfaction with care were demonstrated.

Aged↗
PubMed2004

Role of natriuretic peptides in regulation of conduit artery distensibility.

Arterial distensibility, assessed by the pulse-wave velocity (PWV), is an independent predictor of cardiovascular risk. We investigated whether natriuretic peptides, acting locally, modify conduit artery distensibility in vivo. All studies were conducted in anesthetized sheep (n = 18) by using a validated ovine hindlimb model. In brief, the PWV was calculated, with the use of the foot-to-foot methodology, from two pressure waveforms recorded simultaneously with a high-fidelity dual pressure-sensing catheter placed in the common iliac artery. Drugs were infused either proximally, via the catheter to perfuse the segment of artery under study, or distally, via the sheath to control for any reflex changes in flow or sympathetic activation. First, the effects of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and c-type natriuretic peptide (CNP) were studied. Second, the role of endogenous ANP was investigated by infusing the natriuretic peptide receptor type A (NPRA)-selective receptor antagonist A71915. Third, A71915 was coinfused with ANP. Fourth, the NPRC-selective agonist cANF was infused. Infusion of CNP or des-[Gln18Ser19Gly20Leu21Gly22]-ANF-(4-23)-NH2 (cANF) had no effect on iliac PWV. However, infusion of ANP, and to a lesser degree BNP, resulted in a reduction in PWV (-9%; P < 0.01 and -6%; P < 0.05, respectively). A71915 increased iliac PWV from 2.97 +/- 0.13 to 3.06 +/- 0.13 m/s; P < 0.01. Coinfusion of A71915 with ANP completely abolished the effects of ANP (P < 0.01). Importantly, ANP-BNP infusion via the sheath did not alter PWV. In conclusion, ANP, and to a lesser extent BNP, modify large artery distensibility via the NPRA receptor. Neither CNP nor cANF altered PWV, suggesting that the NPRB and NPRC receptors do not acutely influence distensibility in vivo.

Animals↗
PubMed2004

The role of perceived need within the theory of planned behaviour: a comparison of exercise and healthy eating.

OBJECTIVES: This study examined the effect of perceived need on exercise and healthy eating using the theory of planned behaviour (TPB). In addition, it investigated the determinants of perceived need. METHOD: Participants completed a questionnaire measuring components of TPB and perceived need. A follow-up questionnaire 1 week later measured behaviour. The questionnaires were completed by e-mail. The initial questionnaire was completed by 331 adults, and 286 follow-up questionnaires were returned. RESULTS: Perceived behavioural control was the main predictor of exercise intention and affective attitude was the main predictor of healthy eating intention. Perceived need significantly contributed to the prediction of healthy eating intention but not to exercise intention. Intention and perceived behavioural control predicted actual behaviour but perceived need did not. Reasons reported for the perception of needing to engage in both behaviours mainly focused on physical health and weight control. CONCLUSIONS: Reasons reported for low perceived need suggest that the concept of perceived need may be rather ambiguous, particularly in the case of exercise. Therefore, further research is needed to elucidate the role of perceived need in relation to a variety of health behaviours.

Adult↗
PubMed2004

Cholesterol management of patients with diabetes in a primary care practice-based research network.

OBJECTIVE: To determine the proportion of diabetic patients with and without coronary heart disease (CHD) who attained the American Diabetes Association recommended low-density lipoprotein cholesterol (LDL-C) target level of < or = 2.60 mmol/L (< or = 100 mg/dL). STUDY DESIGN: Retrospective cross-sectional study. METHODS: Patients were identified by searching an electronic medical record database from March 1997 through March 2001. Search strategies included a problem list entry of diabetes mellitus or CHD, a medication in the antidiabetic or nitrate class, or a glycosylated hemoglobin value of > or = 7.0%. Additional information included patient demographics, last LDL-C level, and use of a lipid-lowering agent. RESULTS: The study identified 10,201 patients (4844 with diabetes only, 1243 with diabetes plus CHD, and 4114 with CHD only). A greater proportion of patients who had diabetes and CHD attained the LDL-C target goal compared with patients who had diabetes only (32.1% vs 18.1%; P < .001). Furthermore, patients with diabetes plus CHD were more likely to have a LDL-C level measured within the past year (50.2% vs 42.5% respectively; P < .001). Multivariate logistic regression analysis revealed several factors associated with LDL-C goal attainment, including prior history of CHD, lipid-lowering therapy, tight glycemic control, HMO insurance, and a family medicine provider. CONCLUSION: Although LDL-C goal attainment in patients with diabetes plus CHD was significantly better than that in patients with diabetes only, the prevalence of inadequate control in these high-risk populations is of national concern.

Adult↗
PubMed2003

A comparative study of rotational atherectomy in acute and stable coronary syndromes in the modern era.

Percutaneous rotational coronary atherectomy (PRCA) is commonly used in the percutaneous treatment of diffuse, calcified coronary lesions in stable coronary syndromes (SCSs) and facilitates successful delivery and deployment of balloons and stents. Early experience with PRCA cautioned its use in acute coronary syndromes (ACSs). However, the evolution of the PRCA technique and improved antiplatelet pharmacotherapy has broadened its use in ACSs also. A total of 1,112 consecutive patients with an ACS (n=269) or SCS (n=843) who underwent PRCA of 1,483 lesions were examined retrospectively to evaluate the angiographic and short-term clinical outcomes. Troponin-I was elevated in 33.3% of the ACS group and in 0.6% of the SCS group at baseline (p<0.001). Angiographic complications occurred more frequently in the ACS group (18.6% vs 13.1%, p=0.02). There was no difference in major complications between the groups (ACS 1.1% vs SCS 0.8%; p=0.44). The incidence of any periprocedural creatinine kinase-MB elevation was 17.1% versus 18.9% (p=NS) and 30-day major adverse cardiac events (death, disabling stroke, creatine kinase-MB >3 times the upper limit of normal, urgent revascularization) was 5.9% versus 4.6% (p=NS) when comparing the ACS and SCS groups, respectively. With current techniques and antiplatelet therapy, PRCA can be safely performed in ACSs when lesion morphology dictates, with outcomes comparable to that achieved in SCSs. Although angiographic complications occurred more frequently in the ACS group, this did not result in a significantly higher incidence of postprocedural myonecrosis or 30-day major adverse cardiac events.

Acute Disease↗
PubMed2003

A new scoring system to determine thromboembolic risk after heart valve replacement.

OBJECTIVE: To determine the most important inflammatory and hematologic predictors of thromboembolism (TE) in patients undergoing valve replacement (VR) to be used in conjunction with clinical risk factors for preoperative risk profiling. METHODS AND RESULTS: Preoperative and immediately postoperative clinical, echocardiographic, hematologic, biochemical and microbiological parameters were examined prospectively in 370 patients undergoing VR (249 AVR, 93 MVR, 28 DVR). Mean follow-up was 4.4 years (max 6.6 years; total 1566 pt/yrs), and 96 TE events were documented (28 major and 68 minor). INR data were collected on all patients. Laboratory values were considered elevated if they exceeded the 80th percentile of those of 70 controls with the same distribution of age and gender. IgA antibody to Chlamydia pneumoniae (CP)>or=1:64 was considered indicative of significant infection. Predictors of TE on multivariate analysis following AVR were (hazard ratios): CP infection (2.6), previous TE (2.5), raised eosinophils (2.4), cancer history (2.1), postoperative infection (2.0), hypertension (2.0), CABG x 3/4 (2.0), and diabetes (1.9). Predictors of TE following MVR/DVR were raised mean platelet volume (4.0), raised factor VII (3.1), CP infection (2.7), previous mitral valvotomy (2.5), raised fibrinogen (2.2), and raised reticulocytes (2.0). These risk factors were additive when present in the same patient, enabling a scoring system to be developed that accurately predicted risk of TE based on number of risk factors. CONCLUSIONS: Selected blood tests and clinical risk factors provide a scoring system that accurately predicts TE risk and may guide prosthesis choice and antithrombotic management.

Aged↗
PubMed2003

Atrial natriuretic peptide regulates regional vascular volume and venous tone in humans.

OBJECTIVE: To date, the contribution of basal atrial natriuretic peptide (ANP) levels to resting vascular function in humans is unknown. In the present study we sought to investigate the role of ANP in regulating regional vascular volume and venous tone in healthy subjects. METHODS AND RESULTS: We used radionuclide plethysmography to examine the effects of ANP and the ANP-receptor antagonist A71915 on forearm vascular volume. Creating pressure/volume relations, we determined changes in vascular volume, compliance, and tone. Performing dose-ranging studies, we additionally assessed the potency and specificity of A71915 in the forearm resistance vasculature. Equilibrium blood pool scintigraphy was then used to assess the effects of systemic administration of A71915 on regional intestinal vascular volume. Infusion of ANP increased forearm vascular volume in a dose-dependent manner (maximum 20%; P<0.001), exerting a maximum venodilating effect at plasma levels similar to that seen in heart failure. A71915 increased venous tone, thereby decreasing vascular volume by 9.6+/-1.1%, P<0.001 (forearm), and 2.6+/-0.5%, P=0.01 (intestinal beds). At an infusion ratio of 50:1, A71915 almost completely abolished the effects of ANP on forearm blood flow. CONCLUSIONS: ANP locally regulates regional vascular volume and tone without affecting compliance.

Adult↗
PubMed2002

Assessment of neurocognitive impairment after off-pump and on-pump techniques for coronary artery bypass graft surgery: prospective randomised controlled trial.

OBJECTIVE: To assess neurocognitive impairment after the off-pump and on-pump techniques for coronary artery bypass graft surgery in patients with triple vessel disease. DESIGN: Randomised controlled trial. SETTING: University Hospital of Wales, Cardiff. PARTICIPANTS: 60 patients undergoing coronary artery bypass graft surgery for triple vessel disease prospectively randomised to the off-pump or on-pump technique. MAIN OUTCOME MEASURES: Change in scores in nine standard neuropsychometric tests administered preoperatively and at 1 and 10 weeks postoperatively. RESULTS: The on-pump group showed a significantly greater deterioration in scores for two and three tests at 1 week and 10 weeks postoperatively, respectively, than the off-pump group. The on-pump group also showed a significantly higher incidence of major deterioration in one of the tests both 1 week and 10 weeks postoperatively. The incidence of neurocognitive impairment at 1 week postoperatively was 27% (8 out of 30) in the off-pump group and 63% (19 out of 30) in the on-pump group (P=0.004); and at 10 weeks postoperatively was 10% (3 out of 30) in the off-pump group and 40% (12 out of 30) in the on-pump group (P=0.017). CONCLUSION: Off-pump coronary artery bypass graft surgery results in less neurocognitive impairment than the on-pump technique.

Cognition Disorders↗
PubMed2002

Folic acid improves endothelial function in coronary artery disease via mechanisms largely independent of homocysteine lowering.

BACKGROUND: Homocysteine is a risk factor for coronary artery disease (CAD), although a causal relation remains to be proven. The importance of determining direct causality rests in the fact that plasma homocysteine can be safely and inexpensively reduced by 25% with folic acid. This reduction is maximally achieved by doses of 0.4 mg/d. High-dose folic acid (5 mg/d) improves endothelial function in CAD, although the mechanism is controversial. It has been proposed that improvement occurs through reduction in total (tHcy) or free (non-protein bound) homocysteine (fHcy). We investigated the effects of folic acid on endothelial function before a change in homocysteine in patients with CAD. METHODS AND RESULTS: A randomized, placebo-controlled study of folic acid (5 mg/d) for 6 weeks was undertaken in 33 patients. Endothelial function, assessed by flow-mediated dilatation (FMD), was measured before, at 2 and 4 hours after the first dose of folic acid, and after 6 weeks of treatment. Plasma folate increased markedly by 1 hour (200 compared with 25.8 nmol/L; P<0.001). FMD improved at 2 hours (83 compared with 47 microm; P<0.001) and was largely complete by 4 hours (101 compared with 51 microm; P<0.001). tHcy did not significantly differ acutely (4-hour tHcy, 9.56 compared with 9.79 micromol/L; P=NS). fHcy did not differ at 3 hours but was slightly reduced at 4 hours (1.55 compared with 1.78 micromol/L; P=0.02). FMD improvement did not correlate with reductions in either fHcy or tHcy at any time. CONCLUSIONS: These data suggest that folic acid improves endothelial function in CAD acutely by a mechanism largely independent of homocysteine.

Coronary Artery Disease↗
PubMed2002

Bayesian analysis: a new statistical paradigm for new technology.

Full Bayesian analysis is an alternative statistical paradigm, as opposed to traditionally used methods, usually called frequentist statistics. Bayesian analysis is controversial because it requires assuming a prior distribution, which can be arbitrarily chosen; thus there is a subjective element, which is considered to be a major weakness. However, this could also be considered a strength since it provides a formal way of incorporating prior knowledge. Since it is flexible and permits repeated looks at evolving data, Bayesian analysis is particularly well suited to the evaluation of new medical technology. Bayesian analysis can refer to a range of things: from a simple, noncontroversial formula for inverting probabilities to an alternative approach to the philosophy of science. Its advantages include: (1) providing direct probability statements--which are what most people wrongly assume they are getting from conventional statistics; (2) formally incorporating previous information in statistical inference of a data set, a natural approach which we follow in everyday reasoning; and (3) flexible, adaptive research designs allowing multiple looks at accumulating study data. Its primary disadvantage is the element of subjectivity which some think is not scientific. We discuss and compare frequentist and Bayesian approaches and provide three examples of Bayesian analysis: (1) EKG interpretation, (2) a coin-tossing experiment, and (3) assessing the thromboembolic risk of a new mechanical heart valve.

Bayes Theorem↗
PubMed2002

The impact of working life on health behavior: the effect of job strain on the cognitive predictors of exercise.

The theory of planned behavior (TPB) and R. A. Karasek's (1979) job strain model were used to investigate the predictors of exercise in a group of employees. A total of 241 employees completed an initial questionnaire; 1 week later 213 employees responded to a questionnaire measuring behavior. Employees in high-strain jobs did significantly less exercise than those in low-strain jobs, although they did not intend to do less, suggesting that work may impede the intention implementation. Intenders who failed to exercise had significantly higher work demands and lower exercise self-efficacy than intenders who succeeded in exercising. Work also affected exercise indirectly through self-efficacy. Thus, work may be a target for behavior change intervention because of its impact at 2 stages of the TPB.

Adult↗
PubMed2002

Better anticoagulation control improves survival after valve replacement.

OBJECTIVE: We sought to assess the effect of anticoagulation control on long-term survival after valve replacement with the Medtronic Hall valve (Medtronic, Inc, Minneapolis, Minn). METHODS: Prospective follow-up data, including 82,297 international normalized ratios, were collected for 1476 patients undergoing single valve replacement with the Medtronic Hall valve between 1979 and 1994, with follow-up to the end of 1998. After excluding 204 patients who either died within 30 days or had fewer than 10 international normalized ratios recorded beyond 30 days, there were 10,203 patient years of follow-up for analysis. Anticoagulation variability was measured as the percentage of international normalized ratios outside a target range of 2.0 to 4.0 for each patient. RESULTS: Linearized rates for late death rose progressively with increasing deciles of anticoagulation variability for both aortic and mitral valve replacement (2.7% and 3.3% per year, respectively, in deciles 1 and 2 up to 9.5% and 14.6% per year, respectively, in deciles 6-10; P <.001). Survival at 15 years after aortic valve replacement was 59% for low anticoagulation variability (deciles 1 and 2), 55% for intermediate anticoagulation variability (decile 3), and 28% for high anticoagulation variability (deciles 4-10); survivals at 15 years after mitral valve replacement were 56%, 42%, and 24%, respectively (P <.001 between low-intermediate anticoagulation variability and high anticoagulation variability for both aortic and mitral valve replacement). On multivariate analysis, significant predictors of reduced survival were anticoagulation variability per 20% increase (hazard ratio, 1.8), diabetes (hazard ratio, 1.6), decade of age (hazard ratio, 1.6), concomitant coronary artery bypass grafting (hazard ratio, 1.5), male sex (hazard ratio, 1.4), hypertension (hazard ratio, 1.4), New York Heart Association class III or IV (hazard ratio, 1.3), and non-sinus rhythm (hazard ratio, 1.2). Patients with low anticoagulation variability who were in sinus rhythm and did not have diabetes, coronary bypass grafting, or hypertension had survivals equal to those of the age- and sex-matched general population at 15 years. The incidence of valve-related deaths was significantly higher with high anticoagulation variability compared with the incidence with low-intermediate anticoagulation variability for both aortic (1.4% vs 0.5% per year, P <.001) and mitral valve replacement (1.5% vs 0.5% per year, P <.001). By means of univariate analysis, high anticoagulation variability was significantly associated with New York Heart Association class III or IV at 5 years postoperatively (P <.001) and with age of greater than 60 years at the time of the operation (P =.002). CONCLUSIONS: High anticoagulation variability is the most important independent predictor of reduced survival after valve replacement with a mechanical valve. Better anticoagulation control should improve survival.

Adolescent↗