Defining the rate of nutritional and metabolic derangements after pancreatic resection.

BACKGROUND AND AIMS: Pancreatic resection is associated with pancreatic exocrine insufficiency (PEI) leading to nutritional consequences. The Pancreatic Nutrition Clinic was established to diagnose and manage PEI through standardised nutritional assessment. In this prospective observational study, we aimed to define the rate of PEI, diabetes mellitus and nutritional abnormalities in patients who underwent pancreatic resection. METHODS: All Pancreatic Nutrition Clinic patients were included for analysis. Clinical data were prospectively obtained at initial assessment. Biochemical data included micronutrient levels, faecal elastase-1 and haemoglobin A1c. Bone mineral density and nutritional assessment were undertaken. RESULTS: Ninety-eight patients were included. Fifty-nine per cent (58/98) had undergone a pancreatoduodenectomy. Ninety-three patients had a faecal elastase-1 result, 65% (60/93) of which had a faecal elastase-1 less than 200 µg/g of faeces. Seventy-five patients (76%) of the total population required PERT, and thirty-nine (40%) were classified as malnourished using the patient-generated subjective global assessment tool. Seventy-two per cent (70/97) had a biochemical deficiency of one or more micronutrients. Thirty-eight people (39%) had diabetes mellitus. Of the seventy-eight patients with a bone mineral density scan available for analysis, 29% (23/78) had osteoporosis and 49% (38/78) osteopenia. CONCLUSIONS: Pancreatic exocrine insufficiency, micronutrient deficiency, bone disease, diabetes mellitus and malnutrition are highly prevalent in patients who have undergone pancreatic resection.

Acceptability of technological solutions for overdose monitoring: Perspectives of people who use drugs.

INTRODUCTION: Rising overdose deaths are a devastating problem across the United States and Canada. Despite the availability of observed consumption sites in British Columbia (BC), data suggest people who use drugs (PWUD) alone in private residences are most at risk of overdose death. These individuals may not use consumption sites due to fear of stigmatization, lack of privacy, or personal preference. It is this population that would benefit from overdose monitoring alternatives. METHODS: This 2018 study employed two sources of data. (1) A provincial harm reduction distribution site client survey administered at 27 sites across BC asked about cell phone possession and functionality. (2) Structured interviews with PWUD in Vancouver gathered perspectives regarding monitoring devices and alerting systems. Results: The client survey was administered to 486 individuals. Among 443 respondents, 48% (n = 212) owned a cellphone and 68% (n = 115) of individuals with a cellphone with access to internet (n = 168) would use an application to mitigate opioid-related overdose deaths. Thirty qualitative interviews were performed; thematic analysis of the responses identified three major themes - safety, public versus private drug use, and technological monitoring and function. The relevance of technological devices was affected by the inconsistent availability of cellphones, concerns about anonymity, as well as personal comfort while using drugs. Conclusions: Technological applications may not be suitable for clients with transient lifestyles, no permanent home, and lack of consistent access to a mobile device. Thorough needs assessments, considerations of lifestyle limitations, and understanding perceptions around cellphone and overdose monitoring can increase the potential that devices will be used.Highlights45% (n = 219) of client survey respondents owned a cellphoneOut of cellphone owners, 59% (n = 102) of client survey respondents had access to internetOf 168 with internet access, 68% willing to use any applications for overdose responseApplications not suitable for transient lifestyles, no permanent home, and lack of consistent access to cellphone.

Sweat Testing in Ireland

Introduction Quick, painless, cheap and reliable, the sweat test remains the gold standard diagnostic test for cystic fibrosis. We aimed to describe the pattern of testing in Ireland over a calendar year. Methods Information on sweat test practices was requested from each centre between 1st January 2011 and 31st December 2011, and the number of positive, negative, equivocal, and insufficient samples was recorded. Results In 2011 there were 2555 sweat tests performed in 15 centres, ranging from 35 to over 450 tests per centre. 35 (1.4%) were in the diagnostic range. The overall quantity not sufficient (QNS) rate was 10.3% (range 0-28.3%). Testing was performed across a wide age range (2.5 weeks to 75 years). The mean sweat chloride value was 16.5 mmol/L (SD 16.1 mmol/L). Discussion Our study demonstrates a high number of sweat tests performed in Ireland with significant variation in sweat testing practices across 15 different sites.

Successful orthotopic heart transplantation using a donor heart with ALCAPA.

With the imbalance between donation rates and potential recipients growing, transplant programs are increasingly using non-ideal organs from so-called marginal donors. This is the first reported case of the intentional use of a donor heart with ALCAPA. The recipient was aged one yr with restrictive cardiomyopathy who had been supported with BiVAD for over six months. Function of the donor left ventricle was shown to be well preserved, with no obvious signs of ischemia, except for a fibrotic layer on the anterolateral papillary muscle of the mitral valve. To prevent coronary steal, the anomalous left coronary artery ostium from the MPA was oversewn prior to implantation. The transplanted heart spontaneously regained sinus rhythm immediately following cross-clamp release and showed good contractility from the first postoperative echocardiogram. The patient continues to do well 18 months post-transplant, with excellent function on echocardiography, and good flow on coronary angiography.

BRAF(V600E) Mutation is Associated with Decreased Disease-Free Survival in Papillary Thyroid Cancer.

BACKGROUND: The BRAF (V600E) mutation is a recognised molecular marker in papillary thyroid cancer (PTC), reported incidence from 30 to 80 %. BRAF(V600E) aberrantly activates the MAPK pathway, a central regulator of cell growth and proliferation. Previous studies have reported conflicting data regarding the impact of BRAF(V600E) on clinicopathological features of PTC. The study aims to determine whether BRAF(V600E) is useful as a prognostic biomarker in PTC. METHODS: A cohort study of patients undergoing surgery for PTC was undertaken. The primary outcome measure was disease-free survival. Secondary outcome measures were tumour size, nodal positivity and radioactive iodine ablation rate. All cases were re-examined to confirm PTC. Immunohistochemistry for BRAF(V600E) was performed on tissue microarrays. A single endocrine pathologist, blinded to clinicopathological data, interpreted staining. RESULTS: 496 patients with PTC were included, and 309 (62 %) were BRAF(V600E) positive. Tumour size was similar for BRAF(V600E)-positive and -negative tumours (21.3 vs. 23.2 mm, p = 0.23). BRAF(V600E)-positive patients were significantly older at first operation (mean age 45 versus 49 years, p = 0.003). BRAF(V600E)-positive PTCs had a higher rate of disease recurrence (12.9 vs. 5.6 %, p = 0.004), lymph node metastasis (44 vs. 29.4 %, p = 0.004) and extra-thyroidal extension (44 vs. 22 %, p < 0.001). Five-year disease-free survival was 89.6 % for BRAF(V600E) positive and 96.3 % for negative tumours, p < 0.001. There was no difference between groups for vascular invasion or multifocality. The mean follow-up was 57 months for both groups. CONCLUSION: BRAF(V600E) in PTC predicts an increased risk of lymph node metastasis, extra-thyroidal extension and reduced disease-free survival. It is an additional useful prognostic biomarker.

Clinical experience with Affinity Pixie oxygenation system in paediatric and infant patients.

INTRODUCTION: Great Ormond Street Children's Hospital undertakes over 500 open heart cardiothoracic procedures requiring cardiopulmonary bypass per year. Data from our centre show that many of our neonatal/paediatric patients require higher cardiac indexes than previously thought. We evaluated the new Pixie oxygenation system, rated from 0.1 L/min to 2 L/min, to determine if it could be used for these patients. METHODS: Between 2010 and 2012, 250 Pixie oxygenators were used on consecutive patients requiring correction of congenital cardiac defects. Data were collected on FiO2 requirements, oxygenator pressure drop and gaseous microemboli handling. Retrospective analysis was also undertaken on the procedures and demographics of all patients during 2011-2012 to determine the percentage of patients on whom the Pixie could be used. RESULTS: Analysis of the procedures undertaken at Great Ormond Street Hospital (GOSH) showed that 89% were in patients under 20 kg, requiring a flow rate of <2 L/min (at a base cardiac index of 2.8 L/min/m2). The maximum FiO2 required at 2.5 L/min was 85%. Gaseous microemboli were reduced by 82.5±9.9% and bubble volume was decreased by 94.3±8.4% from the 'venous' pre-oxygenator to the 'arterial' post-oxygenator. DISCUSSION: The Pixie oxygenator proved effective at flows up to 2.5 L/min, with air-handling capabilities comparable with other oxygenators. This represents a single oxygenator that could potentially be used to cover 89% of our surgical procedures. However, we believe that, for the smallest patients (i.e., < 2 kg), a smaller priming oxygenator should be used in order to limit unnecessary haemodilution in this vulnerable group.

Tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral vessels.

Major aortopulmonary collateral arteries (MAPCAs) provide significant issues during cardiopulmonary bypass, including flooding of the surgical field which requires significant blood volumes to be returned to the extracorporeal circuit via handheld suckers. This has been shown to be the major source of gaseous microemboli and is associated with adverse neurological outcome. Use of pH-stat has been previously shown to decrease the shunt through MAPCAs via an unknown mechanism. Here, we report the associated benefits of pH-stat in decreasing sucker usage and gaseous microemboli in a patient with known MAPCAs presenting for repair of tetralogy of Fallot and pulmonary atresia.

Incompatible ABO-plasma exchange and its impact on patient selection in paediatric cardiac transplantation.

OBJECTIVES: A decade ago, the first series of ABO-incompatible heart transplants was published, with surprising and extremely promising results; drastically reduced waiting list mortalities of infants listed for heart transplantation. Essential to the procedure was the process of plasma exchange transfusion, required to reduce isohaemagglutinin titres and facilitate the crossing of ABO blood group boundaries. Since then, Great Ormond Street Hospital, London has offered ABO-incompatible heart transplants to infants who potentially would die waiting for a suitable organ. We report the results of a decade of evolving plasma exchange experience and its impact upon patient selection. METHODS: A retrospective analysis was undertaken of all elective ABO-incompatible heart transplants at Great Ormond Street Children's Hospital from January 2001 until January 2011. Data were sought on underlying conditions and demographics of the patients, the isohaemagglutinin titre before and after plasma exchange and survival figures to date. RESULTS: Twenty-one patients underwent ABO-incompatible heart transplantation, ranging from 3 to 44 months, with preoperative isohaemagglutinin titres ranging from 0 to 1:32. All patients underwent a "3 times" plasma exchange before transplantation, requiring exchange volumes of up to 3209 mL. Postoperative isohaemagglutinin titres ranged from 0 to 1:16. One patient died of causes unrelated to organ rejection. CONCLUSIONS: Our data showed that eight patients (38.1%) were older than the previously suggested 12-month cut-off age. Using a combination of adult reservoir/paediatric oxygenator and extracorporeal circuit, ABO-incompatible plasma exchange transfusions can be undertaken safely using a simplified '3 times' method, reducing the circulating levels of isohaemagglutinins whilst providing minimal circuit size. This allows ABO-incompatible heart transplantation in a broader patient population than previously reported.

Late donor cardiectomy after paediatric heterotopic cardiac transplantation.

BACKGROUND: Cardiac transplantation is a life-saving procedure in infants and children with advanced cardiomyopathy. However, it is greatly limited by shortage of paediatric donors and the complications of long-term immunosuppression, including post-transplant lymphoproliferative disorder (PTLD). We report the management of an infant who had heterotopic cardiac transplantation for advanced cardiomyopathy with secondary pulmonary hypertension who developed seemingly incurable PTLD. METHODS: An 8-month-old girl presented in 1994 with signs of severe heart failure, secondary to dilated cardiomyopathy. At age 11 months, the patient underwent a heterotopic cardiac transplantation. FINDINGS: The patient developed many episodes of PTLD associated with Epstein-Barr virus infection that were resistant to several therapies, including reduction of immunosuppression. Native heart recovery enabled removal of the donor heart 10.5 years after the original operation to allow complete cessation of immunosuppression. Her postoperative course was uncomplicated and the outcome was excellent. 3.5 years after surgery, the patient remains well, in complete remission from her PTLD, and has normal cardiac function. INTERPRETATION: This case shows several issues relating to the use of heterotopic cardiac transplantation in infants and the capacity of the heart to recover. It also provides new insights into the interaction between the immune system with several aspects of modern management of post-transplantation PTLD. FUNDING: None.

Facilitators and barriers to the training and maintenance of young persons' advisory groups (YPAGs).

INTRODUCTION: Increasing demands from public and private healthcare coupled with national initiatives in patient-oriented research has led to an increase in avenues to allow patients to be directly involved in research. In particular, the push towards participation of children and youth has resulted in the formation of pediatric patient advisory groups with broad partnerships and consultation requests across the globe. However, there is a lack of evidence to examine the challenges in formation and training of young persons' advisory groups (YPAGs) and management processes required thereafter. PURPOSE AND OBJECTIVES: This study's purpose is to document YPAG formation and training protocols around the world, highlight common strengths, and evaluate pitfalls and challenges. The results from this study will subsequently inform the development of standardized training protocols for children and youth to be piloted globally. METHODS: In this study, 17 select YPAG team leaders from 7 countries were surveyed to determine current training techniques used within existing groups. 17 youth representatives and 16 team leaders were then interviewed to gather further qualitative data on facilitators and barriers that aid or prevent successful initiation and maintenance of these groups. Qualitative interview data was coded and analyzed using NVivo by two independent reviewers (SYC, VWLT). Any inconsistencies in thematic analysis was confirmed by a third reviewer (JB). RESULTS: The most common training topics include consent and assent (64.71%), clinical trials (64.71%), and patient safety (70.59%). There are significant discrepancies to the amount of training received by each team. Most YPAGs out of the 17 groups receive no formal training (58.82%) while training sessions in the remaining 7 groups vary in both duration and frequency. Collectively, meetings ranged from 15  minutes to 6  hours long, with the majority of team meetings being 2-3  hours long (58.82%). The most common training facilitators are a positive relationship with a local hospital (82.35%) and access to a dedicated team coordinator (64.71%). 70.59% of team leaders identified a lack of access to appropriate educational materials available as a drawback to the impact of their YPAG, making this the greatest common barrier. CONCLUSION: Bringing children and youth to the forefront of paediatric trials and clinical research facilitates appropriate patient representation in subsequent research decision-making. There is an urgency to create and implement standardized protocols for the training of children and youth, especially in preparation for national and international research consultations. This low barrier framework may be of special interest to lower-middle-income countries who wish to encourage community participation in healthcare.

European Contegra multicentre study: 7-year results after 165 valved bovine jugular vein graft implantations.

OBJECTIVE: The valved bovine conduit "Contegra" for RVOT reconstruction became available for clinical use within a 100 % source data monitored and echo core lab controlled prospective European Multicentre Study, carried out from 1999 to 2006. We present the results of this study. METHODS: A total of 165 Contegras were implanted in 8 centres. The mean patient age was 3.9 years (2 days - 18 years, median 2.0). Total follow-up was 687 patient years. Diagnoses included: tetralogy of Fallot (64 patients, 39 %), truncus arteriosus (50, 30 %), double outlet right ventricle (16, 10 %), aortic valve disease/Ross procedure (11, 7 %), pulmonary valve atresia (10, 6 %), transposition of the great arteries (10, 6 %), 4 other malformations (2 %). Previous procedures were: 82 patients (50 %) - none; 37 (22 %) - valved conduit implantation; 14 (8 %) aortopulmonary shunt; 6 (4 %) catheter intervention. Follow-up appointments which included standardised echocardiography investigations were scheduled at 1, 3, 6, and 12 months, then annually. We evaluated freedom from death, explantation, intervention, stenosis, insufficiency, and degeneration. Results were stratified by age, diagnosis group and conduit size. RESULTS: The 5-year freedom-from rates were: explantation - 90 % (for patients aged 1 to 10 years) and 68 % (for younger patients); endocarditis - over 92 %; catheter intervention - 74 % (patients with congenital malformations); stenosis - 75 % and more (any group); insufficiency - 50 % (12 and 14 mm diameter conduits); any event - 13 % (patients under 1 year), 58 % (1 to 10 years), 82 % (> 10 years). Trace or mild insufficiency was a frequent, but not progressive finding. Mild calcification was detected in only 8 examinations. CONCLUSIONS: The performance of the Contegra conduit compares well with that of homografts when used to reconstruct paediatric right ventricular outflow tracts.

Change in biventricular function after cone reconstruction of Ebstein's anomaly: an echocardiographic study.

Aims: The Cone reconstruction in Ebstein's anomaly (EA) aims to reduce tricuspid valve regurgitation (TR) and reposition the valve to the anatomic annulus, but post-operative progress of ventricular function is poorly understood. This study evaluated biventricular function after Cone reconstruction using echocardiographic techniques. Methods and results: A retrospective study assessing longitudinal change was conducted from 2009 to 2014. All symptomatic patients with EA and severe TR undergoing surgery were included. Transthoracic advanced echocardiography was performed pre- and post-operatively (at short-term (<30 days) and mid-term). Conventional and longitudinal 2D strain parameters were measured for left ventricle (LV) and right ventricle (RV). Paired analyses were compared using Wilcoxon Matched-pairs signed rank test. From the 38 patients operated for EA, the echocardiographic data of 17 patients, aged 15 (1-57 years) at operation could be analysed. Median follow up was 6 months (8 days-54 months). The tricuspid annular plane systolic excursion (26.42 ± 5.79 mm vs. 8.75 ± 3.18 mm, P < 0.001), RV fractional area change (FAC) (45.00 ± 8.13% vs. 35.46 ± 5.76%, P = 0.038) and LV 2D peak systolic strain were significantly reduced post-operatively (-20.49 ± 2.79 vs. -17.73 ± 2.76, P = 0.041), with a trend to later recovery for LV 2D strain. There was no evidence of systolic mechanical dys-synchrony before or after operation. Conclusion: Although clinical outcome of Cone reconstruction for EA remains excellent, acute post-operative changes leads to reduction of myocardial function of both ventricles, with a trend to later recovery for LV. Continuing impairment of RV function is multifactorial but may reflect intrinsic myocardial deficiency.

Neuronal circadian clock protein oscillations are similar in behaviourally rhythmic forager honeybees and in arrhythmic nurses.

Internal clocks driving rhythms of about a day (circadian) are ubiquitous in animals, allowing them to anticipate environmental changes. Genetic or environmental disturbances to circadian clocks or the rhythms they produce are commonly associated with illness, compromised performance or reduced survival. Nevertheless, some animals including Arctic mammals, open sea fish and social insects such as honeybees are active around-the-clock with no apparent ill effects. The mechanisms allowing this remarkable natural plasticity are unknown. We generated and validated a new and specific antibody against the clock protein PERIOD of the honeybee Apis mellifera (amPER) and used it to characterize the circadian network in the honeybee brain. We found many similarities to Drosophila melanogaster and other insects, suggesting common anatomical organization principles in the insect clock that have not been appreciated before. Time course analyses revealed strong daily oscillations in amPER levels in foragers, which show circadian rhythms, and also in nurses that do not, although the latter have attenuated oscillations in brain mRNA clock gene levels. The oscillations in nurses show that activity can be uncoupled from the circadian network and support the hypothesis that a ticking circadian clock is essential even in around-the-clock active animals in a constant physical environment.

Combined human and porcine mass chemotherapy for the control of T. solium.

A combined (human and porcine) mass chemotherapy program was tested in a controlled design in 12 village hamlets in the Peruvian highlands. A single dose of 5 mg of praziquantel was given to eliminate intestinal taeniasis in humans, and two rounds of oxfendazole (30 mg/kg) were administered to all pigs. The total population in the study villages was 5,658 resident individuals, and the porcine population at the beginning of the study was 716 pigs. Human treatment coverage was 75%, ranging from 69% to 80%. There were only a few refusals of owners for porcine treatment of their animals. The effect of the intervention was measured by comparing incidence rates (seroconversion in pigs who were seronegative 4 months before) in treatment versus control villages, before and up to 18 months after treatment. There was a clear effect in decreasing prevalence (odds ratio, 0.51; P < 0.001) and incidence (odds ratio, 0.39; P < 0.013) in the treatment area after the intervention, which did not leave to extinction of the parasite but stabilized in slightly decreased rates persisting along the follow-up period. Mass chemotherapy was effective in decreasing infection pressure in this hyperendemic area. However, the magnitude of the effect was small and did not attain the goal of eliminating transmission.

Relation between direct detection of Chlamydia pneumoniae DNA in human coronary arteries at postmortem examination and histological severity (Stary grading) of associated atherosclerotic plaque.

BACKGROUND: Numerous studies have suggested a link between Chlamydia pneumoniae infection, atherosclerosis, and coronary artery disease. However, it is still unclear whether C pneumoniae plays a causal role in the pathogenesis of these conditions. Accordingly, we have performed a systematic dissection of the 3 coronary arteries on 33 postmortem subjects and studied the relationship in individual artery segments between the presence of C pneumoniae DNA and the severity of associated atherosclerosis. METHODS AND RESULTS: The prevalence of C pneumoniae DNA in arterial segments was determined by polymerase chain reaction (PCR) after controlling for the presence of PCR inhibitors. Atherosclerosis in each arterial segment was graded histologically with the Stary classification. C pneumoniae was detected by PCR in 78.8% of subjects, but there was no association between the presence of this DNA and cause of death or grade of atherosclerosis. When paired mild and severe atherosclerotic lesions within subjects were compared, mild lesions were as likely to be positive for C pneumoniae as severe lesions. CONCLUSIONS: This study demonstrates that C pneumoniae can frequently be detected in atheromatous plaques in coronary arteries. However, its distribution did not correlate with severity or extent of disease.

New combination of the old drugs for elderly patients with small-cell lung cancer: a phase II study of the PAVE regimen.

PURPOSE: A regimen of cisplatin, doxorubicin, vincristine, and etoposide (PAVE) was designed for patients with small-cell lung cancer (SCLC) who were older than 65 years, with the following objectives compared with standard chemotherapy regimens: maintain efficacy, diminish toxicity, enhance compliance, and improve chemotherapy administration convenience at an acceptable cost. PATIENTS AND METHODS: The PAVE regimen consisted of cisplatin 30 mg/m2 intravenously (i.v.) day 1; doxorubicin 40 mg/m2 i.v. day 1; vincristine 1.0 mg/m2 i.v. day 1; and etoposide 100 mg/m2 i.v. day 1 and orally days 3 and 5. Cycles were repeated every 3 weeks for four cycles. Patients with limited-stage disease and selected patients with extensive-stage disease received thoracic irradiation delivered concurrently with etoposide-cisplatin (EP) at the time of the second chemotherapy cycle. RESULTS: Sixty-six eligible patients were treated, which included 25 patients with limited-stage disease and 41 patients with extensive-stage disease. Median survival was 70 weeks and 5-year survival was 25% for limited-stage disease. Median survival was 46 weeks for extensive-stage disease. Only one treatment-related death occurred and severe toxicity was infrequent. The median delivered dose-intensity was according to protocol and the mean delivered total dose was 80% of intended. CONCLUSION: The treatment outcome achieved with PAVE in a phase II study of elderly patients compared favorably with published results of standard regimens in patient populations with better prognostic factors. Because the PAVE regimen can be delivered with good compliance, has acceptable toxicity, and is associated with logistic advantages compared with standard regimens, this protocol is suitable for further investigative trials in elderly patients with SCLC.

The prevalence of Chlamydia pneumoniae in atherosclerotic and nonatherosclerotic blood vessels of patients attending for redo and first time coronary artery bypass graft surgery.

OBJECTIVES: To determine if Chlamydia pneumoniae (C. pneumoniae) is more prevalent in atherosclerotic compared with normal blood vessels of patients requiring redo and first time coronary artery bypass graft surgery (CABG). BACKGROUND: Serological and pathological studies have associated atherosclerosis with C. pneumoniae infection. As atherosclerosis is one of the causes of graft failure following CABG, then it may be expected that the prevalence of the organism in failed grafts and diseased native vessels should be greater than in the new grafts. METHODS: Endarterectomy specimens and failed and new grafts were collected from 49 patients with late graft failure. Endarterectomy specimens and new grafts were also collected from nine patients having first time CABG. The presence of C. pneumoniae DNA was then checked for using a nested polymerase chain reaction. RESULTS: The prevalence of C. pneumoniae DNA in failed venous grafts (38.2%) was similar to that in endarterectomy specimens from native coronary arteries (38.5%) and greater than that in new saphenous vein grafts (11.8%). However, it was similar to that in new internal mammary artery grafts (30.0%). Also, the interval between surgery in redo patients was the same regardless of whether C. pneumoniae was present or not. CONCLUSIONS: Cross sectional studies cannot determine whether C. pneumoniae is a cause of atherosclerosis since they do not show whether infection precedes or follows its development. However, our results suggest that the organism is not an important factor in graft failure or atherosclerosis.

Intravenous magnesium in experimental stent thrombosis in swine.

We investigated the effects of magnesium on acute platelet-dependent stent thrombosis in an ex vivo porcine arteriovenous shunt model of high-shear blood flow. Control nitinol stents were expanded to 2 mm in diameter in a tubular perfusion chamber interposed in the shunt and exposed to flowing arterial blood at a shear rate of 2100 s(-1) for 20 minutes (n=156 perfusion runs in 10 swine). Animals were treated with intravenous heparin or MgSO(4) alone (2 g bolus over 20 minutes, followed by 2 g/h infusion) and combined heparin plus MgSO(4) in random fashion. Effects on thrombus weight (TW), platelet aggregation, bleeding time, activated clotting time, mean arterial blood pressure, and heart rate were quantified. Data points in the magnesium-treated animals were examined within 20 minutes after bolus (Mg-early) and >40 minutes after bolus (Mg-late). Stent TW (20+/-3 mg, pretreatment) was reduced by 42+/-21%, 47+/-19%, 48+/-16%, 67+/-12%, and 86+/-8% in the groups treated with Mg-early alone, Mg-late alone, heparin alone, heparin+Mg-early, and heparin+Mg-late, respectively (all P<0.001 versus pretreatment, P<0.001 for heparin+Mg-early and Mg-late versus heparin or magnesium alone, and P<0.05 for heparin+Mg-late versus heparin+Mg-early, ANOVA). Magnesium had no significant effect on platelet aggregation, activated clotting time, or bleeding time. There were no significant effects on heart rate or mean arterial blood pressure. The serum magnesium level was inversely correlated with TW (r=-0.70, P=0.002). In conclusion, treatment with intravenous MgSO(4) produced a time-dependent inhibition of acute stent thrombosis under high-shear flow conditions without any hemostatic or significant hemodynamic complications. Thus, magnesium may be an effective agent for preventing stent thrombosis.