Pre-procedural pacing bias among transcatheter aortic valves with higher post-procedure pacing rates: evidence from the UK TAVI Registry.

Rates of permanent pacemaker (PPM) implantation following transcatheter aortic valve implantation (TAVI) are higher than following surgery and are dependent on patient factors and valve type. There is an increasing trend towards pre-emptive PPM insertion in patients with significant conduction disease prior to TAVI. We report results from the British Cardiovascular Intervention Society (BCIS) on pre- and post-procedural PPM implantation in the TAVI population. All centres in the United Kingdom performing TAVI are required to submit data on all TAVI procedures to the National database which are then reported annually. During 2015, there were 2373 TAVI procedures in the UK. 22.4% of TAVI patients had a PPM implanted either pre-procedure (including the distant past), or during the in-hospital procedural episode. Of these, 7.9% were pre-procedure and 14.5% post-procedure. Overall PPM rates were Edwards Sapien (13.5%), Medtronic CoreValve (28.2%) and Boston Lotus (42.1%; p < 0.01). Pre-procedure pacing rates were Edwards Sapien (6.0%), Medtronic CoreValve (9.1%) and Boston Lotus (12.3%; p < 0.01). Pre-procedural pacing rates for the Boston Lotus valve have risen year-on-year from 5.8% (2013) to 8.6% (2014) to 12.3% (2015). The UK TAVI Registry demonstrates a pre-procedural permanent pacing bias amongst patients receiving transcatheter valves with higher post-procedure pacing rates. Pre-emptive permanent pacing is likely to be responsible for this difference.

Cost-effectiveness of transcatheter aortic valve implantation (TAVI) for aortic stenosis in patients who are high risk or contraindicated for surgery: a model-based economic evaluation.

BACKGROUND: Calcific aortic stenosis (AS) is a common valvular heart disease. Patients with severe symptomatic AS typically survive less than 3 years. In such patients, intervention with surgical aortic valve replacement (SAVR) may increase survival. However, in some patients SAVR is associated with a high operative risk and medical management is considered appropriate. Transcatheter aortic valve implantation (TAVI) is a relatively recent technique to avoid the invasiveness of open surgery. This procedure has been used for the treatment of patients with severe AS who are unsuitable for SAVR (because it is too high risk and/or for other reasons such as suffering from porcelain aorta) and is increasingly being considered for other patients. OBJECTIVES: To determine the cost-effectiveness of TAVI being made available for patients who are high risk or contraindicated for SAVR through a review of existing economic evaluations and development of a model. DATA SOURCES AND REVIEW METHODS: Bibliographic databases [MEDLINE, EMBASE, The Cochrane Library, Health Technology Assessment (HTA), Database of Abstracts of Reviews of Effects (DARE) and NHS Economic Evaluation Database (EED), Centre for Reviews and Dissemination HTA, DARE and NHS EED], guideline resources, current trials registers, websites/grey literature and manufacturers' websites, and consultation with clinical experts were used to identify studies for the review and information for the model. Databases were searched from 2007 to November 2010. A model was built to assess the cost-effectiveness of TAVI separately in patients suitable and unsuitable for SAVR, together with overall results for the effect of making TAVI available. Substantial deterministic sensitivity analysis was carried out together with probabilistic sensitivity analysis. RESULTS: No fully published cost-effectiveness studies were found. Modelling patients not suitable for SAVR, the base-case results show TAVI as more costly but more effective than medical management, with an incremental cost-effectiveness ratio (ICER) of £12,900 per quality-adjusted life-year (QALY). The ICER was below £20,000 per QALY for over 99% of model runs in the probabilistic sensitivity analysis. For patients suitable for SAVR, the comparator with TAVI is a mixture of SAVR and medical management. TAVI is both more costly and less effective than this comparator assuming that most patients would receive SAVR in the absence of TAVI. This is robust to a number of assumption changes about the effects of treatment, but sensitive to assumptions about the proportion of patients receiving SAVR in the comparator. If the use of TAVI is extended to include more patients suitable for SAVR, the overall results from the model become less favourable for TAVI. LIMITATIONS: The modelling involves extrapolation of short-term data and the comparison between TAVI and SAVR is not based on randomised data. More trial data on the latter have been published since the modelling was undertaken. CONCLUSIONS: The results for TAVI compared with medical management in patients unsuitable for surgery are reasonably robust and suggest that TAVI is likely to be cost-effective. For patients suitable for SAVR, TAVI could be both more costly and less effective than SAVR. The overall results suggest that, if a very substantial majority of TAVI patients are those unsuitable for SAVR, the cost-effectiveness of a broad policy of introducing TAVI may fall below £20,000 per QALY. Future work required includes the incorporation of new data made available after completion of this work. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Integration of e-learning resources into a medical school curriculum.

BACKGROUND: E-learning has the potential to make important contributions to medical education, but there has been limited study of a blended approach in which the digital resources are introduced alongside traditional teaching methods such as lectures. METHODS: We describe the successful embedding of an e-learning resource into 3 of the 5 weeks of cardiovascular system teaching for 164 first-year medical students by providing scheduled slots in the timetables. A questionnaire completed by the students at the end of the 5 weeks had a response rate of 66%. Students varied in how they made use of the resource, some systematically working through it and others browsing and studying sections felt to be personally most relevant. RESULTS: Almost all (96%) rated the e-learning resources as probably or definitely of value: they particularly valued interactive activities, animations, video demonstrations, video clips of experts and self-assessment exercises. Graduate students had a significantly more favourable assessment of the e-learning resources than their undergraduate colleagues, while female students felt the value in supporting existing learning opportunities more strongly than male students. CONCLUSIONS: It should not be assumed that all students will choose to use an e-learning resource in the same way and instructional design should enable alternative approaches. The sequence in which the e-learning resource is used in relation to the other learning opportunities, such as lectures and PBL group discussions, may be important and merits further consideration. The experiences reported in this study provide encouragement and pointers for others engaged in the integration of e-learning in their curriculum.

Permanent pacemaker insertion after CoreValve transcatheter aortic valve implantation: incidence and contributing factors (the UK CoreValve Collaborative).

BACKGROUND: Permanent pacemaker (PPM) requirement is a recognized complication of transcatheter aortic valve implantation. We assessed the UK incidence of permanent pacing within 30 days of CoreValve implantation and formulated an anatomic and electrophysiological model. METHODS AND RESULTS: Data from 270 patients at 10 centers in the United Kingdom were examined. Twenty-five patients (8%) had preexisting PPMs; 2 patients had incomplete data. The remaining 243 were 81.3±6.7 years of age; 50.6% were male. QRS duration increased from 105±23 to 135±29 milliseconds (P<0.01). Left bundle-branch block incidence was 13% at baseline and 61% after the procedure (P<0.001). Eighty-one patients (33.3%) required a PPM within 30 days. Rates of pacing according to preexisting ECG abnormalities were as follows: right bundle-branch block, 65.2%; left bundle-branch block, 43.75%; normal QRS, 27.6%. Among patients who required PPM implantation, the median time to insertion was 4.0 days (interquartile range, 2.0 to 7.75 days). Multivariable analysis revealed that periprocedural atrioventricular block (odds ratio, 6.29; 95% confidence interval, 3.55 to 11.15), balloon predilatation (odds ratio, 2.68; 95% confidence interval, 2.00 to 3.47), use of the larger (29 mm) CoreValve prosthesis (odds ratio, 2.50; 95% confidence interval, 1.22 to 5.11), interventricular septum diameter (odds ratio, 1.18; 95% confidence interval, 1.10 to 3.06), and prolonged QRS duration (odds ratio, 3.45; 95% confidence interval, 1.61 to 7.40) were independently associated with the need for PPM. CONCLUSION: One third of patients undergoing a CoreValve transcatheter aortic valve implantation procedure require a PPM within 30 days. Periprocedural atrioventricular block, balloon predilatation, use of the larger CoreValve prosthesis, increased interventricular septum diameter and prolonged QRS duration were associated with the need for PPM.

A family showing recessively inherited multisystem pathology with aberrant splicing of the erythrocyte Band 7.2b ('stomatin') gene.

The case of a French child, born of consanguineous parents of Tunisian origin, is described. He showed a severe multisystem disease with dyserythropoietic, sideroblastic anaemia, delayed neurological development with hypotonia and convulsions, salt-losing nephropathy, chronic watery diarrhoea, lactic acidosis with mitochondrial dysfunction, brittle hair, hypergammaglobulinaemia, fatty liver with intermittent transaminasaemia, and terminal pulmonary fibrosis. Two siblings, of both sexes, were stillborn; two more lived only a short time. One sister is alive and well. SDS gel analysis of the red cell membranes showed a deficiency within 'Band 7' at 32 kDa. Analysis of the gene encoding 'stomatin', or 'erythrocyte membrane protein 7.2b', the principal protein of 'Band 7', revealed a complex series of aberrant spliceforms centred around exon 3, for which no explanatory genomic lesion could be found. The true underlying molecular cause of this condition remains obscure, but it suggests that the stomatin gene should be studied in other cases.

Adoption and integration of simulation-based learning technologies into the curriculum of a UK Undergraduate Education Programme.

CONTEXT: At a time of significant changes in medical education world-wide, the international dimensions and global issues relating to the application of new learning technologies have been recognised. OBJECTIVE: The aim of this paper is to describe the adoption and integration within the curriculum in one United Kingdom (UK) medical school of 'Harvey', the Cardiology Patient Simulator, and the UMedic multimedia computer-based cardiology curriculum - resources developed in a medical school in the USA. PARTICIPANTS: The integration of the resources into the curriculum is described by 3 teachers actively involved in the cardiology curriculum of the UK medical school and 3 teachers associated with the development of resources in the USA. ASPECTS CONSIDERED: The review considers the adoption of Harvey and UMedic in the UK in programmes in relation to: curricular issues, training needs, learning outcomes, curriculum content and sequences of content, educational strategies, teaching and learning methods, assessment, communication about the curriculum and management of the curriculum. CONCLUSIONS: Learning resources, in the form of simulators and computer-based learning modules, developed in one country can be successfully adopted and implemented in another. Facets that facilitated the adoption included close liaison between the developers of the resources in the USA and the implementers in the UK, and careful and systematic planning including in-depth integration of the simulation-based resources into the required curriculum rather than their relegation to a peripheral ad hoc position. The successful use of simulators such as Harvey requires the presence of a 'champion', a clinician educator and a supporting administrative staff who ensure the simulator's appropriate use.

Interaction between glutamine availability and metabolism of glycogen, tricarboxylic acid cycle intermediates and glutathione.

After exhaustive exercise, intravenous or oral glutamine promoted skeletal muscle glycogen storage. However, when glutamine was ingested with glucose polymer, whole-body carbohydrate storage was elevated, the most likely site being liver and not muscle, possibly due to increased glucosamine formation. The rate of tricarboxylic acid (TCA) cycle flux and hence oxidative metabolism may be limited by the availability of TCA intermediates. There is some evidence that intramuscular glutamate normally provides alpha-ketoglutarate to the mitochondrion. We hypothesized that glutamine might be a more efficient anaplerotic precursor than endogenous glutamate alone. Indeed, a greater expansion of the sum of muscle citrate, malate, fumarate and succinate concentrations was observed at the start of exercise (70% VO2(max)) after oral glutamine than when placebo or ornithine alpha-ketoglutarate was given. However, neither endurance time nor the extent of phosphocreatine depletion or lactate accumulation during the exercise was altered, suggesting either that TCA intermediates were not limiting for energy production or that the severity of exercise was insufficient for the limitation to be operational. We have also shown that in the perfused working rat heart, there is a substantial fall in intramuscular glutamine and alpha-ketoglutarate, especially after ischemia. Glutamine (but not glutamate, alpha-ketoglutarate or aspartate) was able to rescue the performance of the postischemic heart. This ability appears to be connected to the ability to sustain intracardiac ATP, phosphocreatine and glutathione.

A common mitochondrial DNA variant associated with susceptibility to dilated cardiomyopathy in two different populations.

Idiopathic dilated cardiomyopathy is a recognised manifestation of mitochondrial disease due to specific mitochondrial (mt) DNA mutations. However, whether mtDNA polymorphisms predispose to sporadic dilated cardiomyopathy is not known. We analysed two populations with this disorder for a general mtDNA variant (T16189C), previously implicated in susceptibility to type 2 diabetes. We noted an increased frequency of the polymorphism in both populations compared with controls (p=0.002). The polymorphism occurred on different mtDNA backgrounds, suggesting that it might be a functional variant. This association of an mtDNA variant with increased susceptibility to dilated cardiomyopathy provides evidence for a mitochondrial cause in sporadic disease.

Video-assisted thoracoscopic sympathectomy for severe intractable angina.

OBJECTIVE: Endoscopic trans-thoracic sympathectomy is a well documented, safe and successful treatment for palmar and axillary hyperhidrosis. This may also be helpful in the management of patients with intractable angina and advanced coronary disease unsuitable for coronary artery bypass graft (CABG) or percutaneous transluminal coronary angioplasty (PTCA). We evaluated video assisted thoracoscopic sympathectomy (VATS) in such patients with the aim of improving symptoms and quality of life. METHODS: Video assisted thoracoscopic sympathectomy, a minimally invasive procedure, was performed under general anaesthesia with alternating single lung ventilation. Three stab incisions were made at the level of the fourth intercostal space in the anterior and posterior axillary lines, and at the fifth intercostal space in the mid-axillary line through which an extensive thoracic sympathectomy was performed to include second to the fourth ganglia, bilaterally. RESULTS: A total of 16 patients aged 46-76 (mean 61) years were assessed for VATS. Of these 10 patients had the procedure performed; nine with previous CABG and one with diffuse coronary disease. Six patients were excluded because of an evolving MI (n = 1), left ventricular ejection fraction (LVEF) < 30% (n = 2), and chronic stable angina with no objective evidence of ischaemia (n = 3). All 10 patients had marked symptomatic improvement with reduction of both angina frequency and intensity of attacks. Mean follow-up period 11.5 months. Exercise tolerance and time to onset of angina measured on exercise treadmill was significantly increased post-VATS (P = 0.028) and maintained 1 year post-operative. CONCLUSION: VATS was associated with both reduction in angina symptoms and an increase in exercise time to onset of angina. An improved quality of life was evident.

Amino acid transport during muscle contraction and its relevance to exercise.

The functional significance of amino acid transport in skeletal muscle has been explored by the use of a variety of techniques including work in isolated perfused organs, isolated incubated organs and tissue culture of muscle cells. The results suggest that although there is a wide variety of amino acid transport systems of different characteristics and with different responses to ionic, hormonal and nervous modulation, the amino acid glutamine (transported by system Nm) demonstrates some unusual properties not observed with amino acids transported by other systems. Glutamine is transported at very high rates in skeletal muscle and heart and both the glutamate and glutamine transporter appear to be adaptively regulated by the availability of glutamine. Glutamine appears to be involved in the regulation of a number of important metabolic processes in heart and skeletal muscle (e.g., regulation of the glutathione reduced/oxidised ratio and regulation of protein and glycogen synthesis). Furthermore, glutamine transport appears to interact with systems for regulation of volume control and many of the metabolic features attributable to changes in glutamine concentration appear to be modulated via alteration in cytoskeletal status.

Effects of L-glutamine on post-ischaemic cardiac function: protection and rescue.

UNLABELLED: We investigated the effects of L-glutamine (0-20 mM) on cardiac function. The isolated perfused working rat heart (left atrial and aortic pressures of 5 and 70 cm H2O, respectively) was subjected to 20 min of normothermic low-flow ischaemia followed by reperfusion for 35 min. In the absence of glutamine, ischaemia-reperfusion caused an immediate significant (P < 0.01) fall in cardiac output from 46 to 20 ml/min, with a further deterioration to 17 ml/min at 35 min reperfusion. Ischaemia also caused a significant (P < 0.05) fall in myocardial glutamate from 2.6 to 1.8 mumol/g wet weight; and ischaemia-reperfusion caused significant (each P < 0.05) diminutions of myocardial ATP from 3.5 to 1.0 mumol/g wet weight and phosphocreatine from 4.8 to 1.5 mumol/g wet weight and resulted in significant (P < 0.05) accumulation of myocardial lactate from 0.9 to 4.3 mumol/g wet weight. Glutamine, present throughout the perfusion protocol (i.e. prior to ischaemia), at or above 1.25 mM, prevented the post-ischaemic diminution of cardiac output and the deleterious changes in myocardial metabolites. Post-ischaemic treatment with glutamine at 2.5 mM completely prevented the post-ischaemic diminution of cardiac output and restored the myocardial metabolites to normal. CONCLUSIONS: Glutamine may be suitable as a cardioprotective and rescue agent. These effects may be mediated by maintenance of myocardial glutamate, ATP and phosphocreatine: and prevention of lactate accumulation.

Glutamine metabolism and transport in skeletal muscle and heart and their clinical relevance.

The glutamine and glutamate transporters in skeletal muscle and heart appear to play a role in control of the steady-state concentration of amino acids in the intracellular space and, in the case of skeletal muscle at least, in the rate of loss of glutamine to the plasma and to other organs and tissues. This article reviews what is currently known about transporter characteristics and mechanisms in skeletal muscle and heart, the alterations in transport activity in pathophysiological conditions and the implications for anabolic processes and cardiac function of altering the availability of glutamine. The possibilities that glutamine pool size is part of an osmotic signaling mechanism to regulate whole body protein metabolism is discussed and evidence is shown from work on cultured muscle cells. The possible uses of glutamine in maintaining cardiac function perioperatively and in promoting glycogen metabolism are discussed.

Concealed post-infarction left ventricular rupture--a diagnostic dilemma.

We describe a patient with post-infarction left ventricular rupture exhibiting several atypical features. A successful outcome was achieved after serendipitous surgery.

Glutamine transport and its metabolic effects.

This paper surveys current information concerning the characteristics of glutamine transport in skeletal muscle and heart and presents evidence for a regulatory role of amino acid transporters under certain physiological and pathophysiological circumstances. In particular, attention is focused upon the properties and regulatory modulation of System Nm, the transporter with the highest capacity for transmembrane glutamine exchange in rat and human skeletal muscle. Much of the observed behaviour of the glutamine-free pool in skeletal muscle in health and disease can be explained by alterations in the activity of this transporter. Like the System A transporters in liver and muscle System Nm shows adaptive regulation in response to altered availability of extracellular glutamine. The effects of glutamine in skeletal muscle include the stimulation of protein synthesis which occurs in the absence or presence of insulin, the response being greater with insulin. Integrative features of the transport and metabolic effects of glutamine and other amino acids are discussed.