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Biomedical subjects

T Treasure

Publications and source records attributed to T Treasure.

At least 37 records · Page 2Linked to original sources
PubMed1997

Meta-analysis of the association of enteroviruses with human heart disease.

The role of viruses in the genesis of both dilated cardiomyopathy (DCM) and acute myocarditis remains uncertain. Modern molecular techniques such as polymerase chain reaction (PCR) and in situ hybridisation are sensitive means of detecting viral genomic material in human myocardial tissue and may help to resolve the quest. Meta-analysis of the papers in the literature records studies of both acute myocarditis and DCM where molecular techniques were used to demonstrate enteroviruses. This review studies information from the published literature as well as statistical analysis of the cumulative molecular data relating enteroviruses to DCM, and to compare these findings with the information available on the role of enteroviruses in acute myocarditis. Twelve papers reported studies in acute myocarditis, of which 11 found higher percentages of enteroviral RNA positivity in the diseased population, giving an overall odds ratio of 4.4. Seventeen papers reported studies in DCM, with 11 recording higher positivity rates in these patients. Cumulative analysis of these data suggests an overall odds ratio of 3.8. The causative role of enteroviruses in acute myocarditis, particularly in children, is supported by meta-analysis of the available literature. The data on DCM is suggestive of an association but a proportion of the studies are negative.

Cardiomyopathy, Dilated↗
PubMed1996

Quality of life, employment status, and anginal symptoms after coronary angioplasty or bypass surgery. 3-year follow-up in the Randomized Intervention Treatment of Angina (RITA) Trial.

BACKGROUND: The Randomized Intervention Treatment of Angina (RITA) trial compares initial policies of percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass graft surgery (CABG) in 1011 patients with angina. This report assesses the impact of these revascularization procedures on angina, quality of life (according to the Nottingham Health Profile), and employment over 3 years of follow-up. METHODS AND RESULTS: Both interventions produced marked improvement in all quality-of-life dimensions (energy, pain, emotional reactions, sleep, social isolation, and mobility) and seven aspects of daily living. Patients with angina at 2 years had more quality-of-life impairment than angina-free patients, whose perceived health was similar to population norms. This reflects the close link at baseline between angina grade and quality of life. The slightly greater impairment of quality of life in PTCA compared with CABG patients is a result of their significantly higher chances of having angina, especially after 6 months. Employment status was investigated mainly for men < or = 60 years old. PTCA patients returned to work sooner (40% at 2 months compared with 10% of CABG patients), but the latter caught up by 5 months. After 2 years, 22% and 26% of CABG and PTCA patients, respectively, were not working for cardiac reasons. Patients with angina at 2 years were much more likely to be unemployed than those without. CONCLUSIONS: The impact of angina on quality of life and unemployment is greatly alleviated by PTCA or CABG. Angina is avoided more successfully with CABG, but PTCA offers a speedier return to work. Both intervention strategies then produce similar benefits for quality of life and employment over several years.

Angina Pectoris↗
PubMed1996

Effect of magnesium on the monophasic action potential during early ischemia in the in vivo human heart.

OBJECTIVES: This study sought to examine the effects of magnesium on epicardial action potential duration in patients during early myocardial ischemia. BACKGROUND: Magnesium has been shown to reduce arrhythmias in experimental models of myocardial ischemia. Experimental and clinical observations suggest an effect on repolarization. METHODS: Patients undergoing elective coronary artery bypass surgery were randomized (double blind) to receive intravenous magnesium (n = 10) or placebo (n = 10). Patients were placed on cardiopulmonary bypass and paced at 600 ms, and stable monophasic action potentials were obtained. Ischemia was achieved by aortic cross-clamping for 2 min while normothermia was maintained. RESULTS: Serum magnesium levels increased from 0.60 +/- 0.03 to 1.69 +/- 0.07 mmol/liter (mean +/- SEM) in the magnesium group, with no change in the placebo group. Epicardial temperature was identical in the two groups and did not alter during ischemia. At 90% repolarization, initial action potential prolongation was observed in the placebo group over the first minute of ischemia (282.0 +/- 6.0 to 294.0 +/- 4.8 ms) but not in the magnesium group (278.3 +/- 5.9 to 274.5 +/- 7.4 ms). At 2 min of ischemia, action potential duration was shorter in the magnesium group than in the placebo group (258.1 +/- 5.5 vs. 281.3 +/- 5.9 ms, respectively, p < 0.05). CONCLUSIONS: Intravenous magnesium infusion altered the epicardial action potential response to ischemia in patients. These findings may have important implications in the pathogenesis of arrhythmias in ischemic myocardium.

Action Potentials↗
PubMed1996

Type B dissection involving a right-sided aortic arch.

Type B dissection involving a right-sided aortic arch is a very rare condition. Here we describe such an occurrence in an elderly patient who was initially managed medically but later underwent successful surgical repair after developing symptoms of expanding dissection. The dissection was approached through a right thoracotomy. Because of the unusual origin of the arch vessels and the direction of the dissected segment, aortic clamps could not be positioned satisfactorily, necessitating the use of full cardiopulmonary bypass and deep hypothermic circulatory arrest for the repair. The indications for surgery in Type B dissection and the modifications in the surgical strategy necessitated by the abnormal anatomy are discussed.

Aged↗
PubMed1996

A prospective randomised controlled trial of postoperative autotransfusion with and without a heparin-bonded circuit.

Autotransfusion has been included in the routine protocol in some units as an effort towards blood conservation. In this study we aimed to measure the efficacy and limitations of autotransfusion and whether a heparin-bonded circuit had any advantage. One hundred five patients were randomised to one of three post-operative treatments. Group 1 (n = 34) was not autotransfused whereas groups 2 (n = 36) and 3 (n = 35) received autotransfusion with the circuit of group 3 coated with heparin. Homologous blood and blood products were given according to strict protocols identical for all groups. Transfused and circulating blood was analysed for haemostatic variables and the requirement for homologous blood was recorded. Autotransfused blood contained no intact platelets and very high levels of D-Dimers (a peptide fragment released when fibrin is lysed) which resulted in high levels of systemic D-Dimers in patients receiving autotransfusion. Flow cytometric analysis revealed that whilst platelet glycoprotein 1 b receptors were severely reduced immediately following surgery, there was no additional damage caused by autotransfusion. Furthermore, there was no difference in platelet aggregation, von Willebrand factor (vWF) multimetric analysis or clotting profiles between the groups. Median (interquartile range) blood loss was 898 ml (638-1195) in group 1, 853 ml (595-1348) in group 2 and 770 ml (615-1000) in group 3 (Kruskal-Wallis P = 0.46). Median transfusion requirements were 2 units in each group. Whilst auto-transfusion does not appear to compromise haemostasis, it does not reduce the requirement for homologous blood and heparin-bonding of the circuit has no impact.

Aged↗
PubMed1996

Ischaemic preconditioning and cardiac surgery.

OBJECTIVE: This review discusses the phenomenon of ischaemic preconditioning and its potential application to cardiac surgery. The biology of ischaemic preconditioning is explained and the more limited evidence suggesting that the human heart can be preconditioned is discussed. METHODS AND RESULTS: It is now accepted that the heart is capable of short-term rapid adaptation in response to brief ischaemia so that during a subsequent, more severe ischaemic insult myocardial necrosis is delayed-ischaemic preconditioning. The infarct-delaying properties of ischaemic preconditioning have been observed in all species studied. Five minutes of ischaemia is enough to initiate preconditioning and the protective period lasts for 1-2 h. Laboratory experiments have demonstrated that the stimulation of adenosine receptors initiates preconditioning and the intracellular signal transduction mechanisms involve protein kinase C and ATP-dependent potassium channels, although there may be some differences between species. An analysis of studies on myocardial infarction in humans has revealed that some patients reporting angina in the days before infarction have a better outcome and this may be due to the ischaemia causing preconditioning. More direct evidence has come from an investigation of patients undergoing percutaneous transluminal angioplasty in whom the ST-segment changes induced by balloon inflation were more marked during the first inflation than the second. In patients undergoing coronary artery bypass grafting the decline in ATP content during the first 10 min of ischaemia was reduced in patients subjected to a brief preconditioning protocol. CONCLUSIONS: Preconditioning is a powerful and reproducible method of protecting the myocardium from irreversible ischaemic injury. There is now evidence indicating that the human heart can be preconditioned. However, more trials are necessary in patients undergoing cardiac surgery before the role of preconditioning as a means of myocardial protection can be assessed.

Adenosine Triphosphate↗
PubMed1996

Reciprocal inhibition of nitric oxide and prostacyclin synthesis in human saphenous vein.

1. Angiotensin II (AII) causes contraction of isolated rings of human saphenous vein, responses that are attenuated by the presence of functional endothelium. In this study, we have investigated the mechanisms controlling the release by AII of two endothelial-derived vasorelaxants, prostacyclin (PGI2) and nitric oxide (NO). 2. Myotropic and biochemical changes were measured in response to AII. The biochemical responses measured were the output of PGI2 (as 6-oxo-PGF1 alpha) and of NO (as cyclic GMP). Inhibitors of cyclo-oxygenase (COX; piroxicam) or NO synthase (NOS; L-NAME), were added to the system to determine the influence of endogenous prostaglandins and NO on both myotropic and biochemical responses. Furthermore, to mimic the effects of endogenous, PGI2 or NO, exogenous forms of these relaxants were added, during inhibition of their endogenous release. 3. Contractions of the rings of saphenous vein in response to AII (1-100 nM) were unaffected by treatment with either piroxicam (5 microM) or L-NAME (200 microM) individually. However, when these two inhibitors were used together, there was an increase in the contractions in response to AII. 4. Biochemical analyses revealed that during stimulation by AII, levels of PGI2 and NO were enhanced when synthesis of the other vasodilator was inhibited, suggesting that endogenous NO inhibits PGI2 synthesis and endogenous, PGI2 or another vasorelaxant PG can inhibit NO synthesis. 5. Exogenous PGI2 (as iloprost) or NO (from glyceryl trinitrate) inhibited the increased output of endogenous NO or PGI2 respectively. 6. These results demonstrate the presence, in human saphenous vein, of a mechanism which ensures that levels of vasodilatation are maintained through a compensatory increase in one relaxant agonist when output of the other is decreased. If present in vivo such a mechanism would be important in maintaining saphenous vein graft patency as both PGI2 and NO are not only vasodilators, but inhibit platelet aggregation and myoinitimal hyperplasia, processes implicated in degeneration of graft function.

Angiotensin II↗
PubMed1996

Demographic characteristics of patients undergoing aortic valve replacement for stenosis: relation to valve morphology.

OBJECTIVE: To determine the relative importance of the different causes of isolated aortic valve stenosis in a surgical series, and to relate these to patient characteristics including the rate of insertion of bypass grafts for coronary artery disease. DESIGN: Survey of the clinical and pathological data on patients undergoing aortic valve replacement for isolated stenosis. SETTING: Tertiary care cardiothoracic surgical unit. PATIENTS AND METHODS: 465 adult patients undergoing aortic valve replacement representing a consecutive series in one surgical unit. Retrospective review of patients records and classification of cause of aortic stenosis based on pathological examination of excised valve cusps. RESULTS: 63.7% patients had calcific bicuspid valves, 26.9% tricuspid calcific valves, and 5.4% rheumatic, 2.6% mixed pathology and 1.5% unicommissural valves. The ratio of males to females for bicuspid valves was 1.85:1 and for tricuspid calcific valves 0.76:1. The mean age of patients with bicuspid valves was 64.9 years compared with 73.4 years for those with tricuspid valves. Some 22.3% of patients with bicuspid valves and 44.8% of those with tricuspid valves had sufficient coronary artery disease to necessitate insertion of coronary bypass grafts. The differential rate of insertion of coronary bypass grafts was independent of age. CONCLUSIONS: Bicuspid calcified aortic valves are the predominant cause of isolated aortic valve stenosis followed by tricuspid calcified aortic valves. The sex and age distribution of bicuspid and tricuspid calcific aortic valve stenosis is different. The higher rate of insertion of vascular grafts in tricuspid calcific aortic valves may indicate that risk factors for atherosclerosis enhance cusp calcification in these patients.

Adult↗
PubMed1996

Training surgeons and safeguarding patients.

Surgical trainees need exposure to a wide variety of operations and a chance to operate under supervision. At the same time there is the over-riding responsibility to do the best for our patients. Cardiac surgery is dominated by coronary bypass surgery and the tendency has been to delegate easy coronary cases to trainees and to neglect their experience in other areas. This paper is an audit of trainee exposure and supervision in a training centre. During a 20-month period, 35.2 per cent of cases were delegated; 20.6 per cent to the senior registrar and 14.6 per cent to the registrars. Senior registrars were assisted by the consultant in 19.1 per cent of their cases and registrars were assisted by more senior colleagues in 28.5 per cent of theirs. Most cases delegated to trainees were of low perioperative risk and operations were performed with commensurate low morbidity and mortality. The delegation of valve surgery was disproportionately low in comparison to overall case mix. On the basis of this study, the delegation of cases is being reviewed in the knowledge that with appropriate selection, trainees can gain valuable operative experience without compromising patient-safety.

Aged↗
PubMed1996

The role of echocardiography in the diagnosis of aortic dissection.

Echocardiography is now an integral part of the assessment of patients before, during and after cardiac surgery. For example, mitral valve repair or myectomy would rarely now be contemplated without echocardiography. Echocardiography is essential for the correct diagnosis of valve disease and to plan the appropriate timing of valve surgery, for the assessment of left ventricular function, for the detection of many postoperative complications, and for the follow up after valve surgery or repair of aortic dissection. Although surgeons are increasingly well trained in echocardiography, a specialist in the technique is still required in order to keep abreast of the dramatic advances in technology and interpretation which have occurred over the past five years and which continue unabated.

Aortic Dissection↗
PubMed1995

Resternotomy for bleeding after cardiac operation: a marker for increased morbidity and mortality.

Over a 2-year period from January 1, 1992, to December 31, 1993, of 2,221 patients undergoing cardiac operations in our unit, 85 (3.8%) were reopened for the control of bleeding (9 patients more than once). The incidence of resternotomy in coronary cases was 2.3%, but resternotomy was more than three times as likely in valve cases (odds ratio, 3.4; 95% confidence interval, 2.1 to 5.4). Previous cardiac operation was more common among resternotomy patients than among the remainder (18% versus 9%, respectively; p = 0.018). An identifiable source of bleeding was found in 57 of the 85 patients (67%), but a concurrent coagulopathy was common (45 patients). Resternotomy patients, as a group, had higher preoperative risk scores (Parsonnet) than did the other patients (p < 0.0001), stayed longer in the intensive care unit (p < 0.0001), and had greater requirements for intraaortic balloon counterpulsation (14% versus 3%) and hemofiltration (9% versus 3%) (p < 0.0001 and p < 0.01, respectively). Nineteen resternotomy patients (22%) died in the hospital, a proportion significantly greater than the risk assigned to this group of patients preoperatively (12.8%) (p = 0.008). In contrast, the observed mortality for the other 2,136 patients (5.5%) was significantly less (8.3%) (p < 0.00006). Multiple forward stepwise logistic-regression analysis confirmed resternotomy for excessive bleeding after cardiac operation to be a significant independent predictor of a prolonged stay in the intensive care unit (p < 0.0001), the need for intraaortic balloon counterpulsation (p < 0.0001), and death (p < 0.0001).

Aged↗
PubMed1995

Survival and quality of life in patients with protracted recovery from cardiac surgery. Can we predict poor outcome?

Of all the 2256 adult cardiac surgical patients operated upon during a 12-month period from 1st February 1992 in three units, only 162 (7.2%) spent more than 48 h in the intensive care unit (ICU) (median 6 days, range 3-90). There were 47 deaths in ICU, 7 more before hospital discharge, and a further 10 before the study end-point of one year after surgery. All 98 1-year survivors were at home with 86 of them reporting their quality of life, on formal evaluation, to be within the reference range which we have established for a less complicated cohort of cardiac surgical patients. Prospectively collected physiological measurements were used in a mathematical model to test how well we could predict which patients will die and which of the survivors have a poor quality of life. The algorithm performs well for cardiac surgery patients with a specificity of 98%. If treatment had been withdrawn when death or poor quality of life became predictable, the maximum number of ICU bed days that could be freed was of the order of 2%. The plight of these patients is distressing, but most survive and do well and they are infrequent compared with the large majority who survive to leave hospital after a short ICU stay.

Adult↗