'Super Rehab': can we achieve coronary artery disease regression? A feasibility study protocol

INTRODUCTION

Patients diagnosed with coronary artery disease (CAD) are currently treated with medications and lifestyle advice to reduce the likelihood of disease progression and risk of future major adverse cardiovascular events (MACE). Where obstructive disease is diagnosed, revascularisation may be considered to treat refractory symptoms. However, many patients with coexistent cardiovascular risk factors, particularly those with metabolic syndrome (MetS), remain at heightened risk of future MACE despite current management.Cardiac rehabilitation is offered to patients post-revascularisation, however, there is no definitive evidence demonstrating its benefit in a primary prevention setting. We propose that an intensive lifestyle intervention (Super Rehab, SR) incorporating high-intensity exercise, diet and behavioural change techniques may improve symptoms, outcomes, and enable CAD regression.This study aims to examine the feasibility of delivering a multicentre randomised controlled trial (RCT) testing SR for patients with CAD, in a primary prevention setting.

METHODS AND ANALYSIS

This is a multicentre randomised controlled feasibility study of SR versus usual care in patients with CAD. The study aims to recruit 50 participants aged 18-75 across two centres. Feasibility will be assessed against rates of recruitment, retention and, in the intervention arm, attendance and adherence to SR. Qualitative interviews will explore trial experiences of study participants and practitioners. Variance of change in CAD across both arms of the study (assessed with serial CT coronary angiography) will inform the design and power of a future, multi-centre RCT.

ETHICS AND DISSEMINATION

Ethics approval was granted by South West-Frenchay Research Ethics Committee (reference: 21/SW/0153, 18 January 2022). Study findings will be disseminated via presentations to relevant stakeholders, national and international conferences and open-access peer-reviewed research publications.

TRIAL REGISTRATION NUMBER

ISRCTN14603929.

Investigating the impact of non-gated thoracic CT prior to CTCA to reduce layered testing

AIM

To determine the proportion of computed tomography (CT) coronary angiography (CTCA) referrals with coronary artery calcification (CAC) evident on previous non-cardiac CT imaging and how this impacted the diagnostic yield for CTCA, the requirement for additional diagnostic testing, and the associated costs to confirm or refute obstructive coronary artery disease (CAD).

MATERIALS AND METHODS

A retrospective review of CTCA examinations was undertaken between 01/05/2018 and 31/05/2020 in which the examinations were cross referenced for previous non-gated thoracic CT at Royal United Hospitals Bath. Major epicardial vessel CAC on baseline CT was re-evaluated by published semi-quantitative methods, giving a per-patient CAC score (mild = 1-3, moderate = 4-6, severe >6). Subsequent incomplete CTCA diagnostic yield, further testing, and cost implications were examined.

RESULTS

Of the 2140 CTCA examinations identified, 13% (280/2140) had a preceding non-gated thoracic CT (53% female, age 63 ± 11 years). The incomplete diagnostic rate increased with CAC grade, mild 32%, (RR 12; 95% CI 4-40), moderate 64% (RR 25; 95% CI 8-80), severe 75%, (RR 29; 95% CI 9-94). Additional diagnostic testing occurred in 4% for the mild CAC category, and 14% and 42% for moderate and severe, respectively. When severe CAC was identified on a non-gated thoracic CT a cost saving of £171/patient (dobutamine stress echo [DSE]) and £61/patient (myocardial perfusion scintigraphy [MPS]) was established with a direct to functional testing pathway.

CONCLUSIONS

In patients referred for CTCA where severe CAC was identified on a preceding non-gated thoracic CT a direct to functional testing altered management in 42% of cases and was cost-effective.

Validation of the MIRACLE2 Score for Prognostication After Out-of-hospital Cardiac Arrest

Background

Out-of-hospital cardiac arrest (OHCA) is associated with very poor clinical outcomes. An optimal pathway of care is yet to be defined, but prognostication is likely to assist in the challenging decision-making required for treatment of this high-risk patient cohort. The MIRACLE2 score provides a simple method of neuro-prognostication but as yet it has not been externally validated. The aim of this study was therefore to retrospectively apply the score to a cohort of OHCA patients to assess the predictive ability and accuracy in the identification of neurological outcome.

Methods

Retrospective data of patients identified by hospital coding, over a period of 18 months, were collected from a large tertiary-level cardiac centre with a mature, multidisciplinary OHCA service. MIRACLE2 score performance was assessed against three existing OHCA prognostication scores.

Results

Patients with all-comer OHCA, of presumed cardiac origin, with and without evidence of ST-elevation MI (43.4% versus 56.6%, respectively) were included. Regardless of presentation, the MIRACLE2 score performed well in neuro-prognostication, with a low MIRACLE2 score (≤2) providing a negative predictive value of 94% for poor neurological outcome at discharge, while a high score (≥5) had a positive predictive value of 95%. A high MIRACLE2 score performed well regardless of presenting ECG, with 91% of patients receiving early coronary angiography having a poor outcome.

Conclusion

The MIRACLE2 score has good prognostic performance and is easily applicable to cardiac-origin OHCA presentation at the hospital front door. Prognostic scoring may assist decision-making regarding early angiographic assessment.

Time to TAVI: streamlining the pathway to treatment

INTRODUCTION

Severe aortic stenosis is a major cause of morbidity and mortality. The existing treatment pathway for transcatheter aortic valve implantation (TAVI) traditionally relies on tertiary Heart Valve Centre workup. However, this has been associated with delays to treatment, in breach of British Cardiovascular Intervention Society targets. A novel pathway with emphasis on comprehensive patient workup at a local centre, alongside close collaboration with a Heart Valve Centre, may help reduce the time to TAVI.

METHODS

The centre performing local workup implemented a novel TAVI referral pathway. Data were collected retrospectively for all outpatients referred for consideration of TAVI to a Heart Valve Centre from November 2020 to November 2021. The main outcome of time to TAVI was calculated as the time from Heart Valve Centre referral to TAVI, or alternative intervention, expressed in days. For the centre performing local workup, referral was defined as the date of multidisciplinary team discussion. For this centre, a total pathway time from echocardiographic diagnosis to TAVI was also evaluated. A secondary outcome of the proportion of referrals proceeding to TAVI at the Heart Valve Centre was analysed.

RESULTS

Mean±SD time from referral to TAVI was significantly lower at the centre performing local workup, when compared with centres with traditional referral pathways (32.4±64 to 126±257 days, p<0.00001). The total pathway time from echocardiographic diagnosis to TAVI for the centre performing local workup was 89.9±67.6 days, which was also significantly shorter than referral to TAVI time from all other centres (p<0.003). Centres without local workup had a significantly lower percentage of patients accepted for TAVI (49.5% vs 97.8%, p<0.00001).

DISCUSSION

A novel TAVI pathway with emphasis on local workup within a non-surgical centre significantly reduced both the time to TAVI and rejection rates from a Heart Valve Centre. If adopted across the other centres, this approach may help improve access to TAVI.

CT coronary angiography first prior to rapid access chest pain clinic review: a retrospective feasibility study

OBJECTIVES

Since rapid access chest pain clinics (RACPC) were established to streamline stable chest pain assessment, CT coronary angiography (CTCA) has become the recommended investigation for patients without known coronary artery disease (CAD), with well-defined indications. This single-centre retrospective study assessed the feasibility of General Practice (GP)-led CTCA prior to RACPC.

METHODS

RACPC pathway patients without pre-existing CAD electronic records were reviewed (September-October 2019). Feasibility assessments included appropriateness for RACPC, referral clinical data vs RACPC assessment for CTCA indication and safety, and a comparison of actual vs hypothetical pathways, timelines and hospital encounters.

RESULTS

106/172 patients screened met inclusion criteria (mean age 61 ± 14, 51% female). 102 (96%) referrals were 'appropriate'. No safety concerns were identified to preclude a GP-led CTCA strategy. The hypothetical pathway increased CTCA requests vs RACPC (84 vs 71), whilst improving adherence to guidelines and off-loading other services. 22% (23/106) had no CAD, representing cases where one hospital encounter may be sufficient. The hypothetical pathway would have reduced referral-to-diagnosis by at least a median of 27 days (interquartile range 14-33).

CONCLUSION

A hypothetical GP-led CTCA pathway would have been feasible and safe in a real-world RACPC patient cohort without pre-existing CAD. This novel strategy would have increased referrals for CTCA, whilst streamlining patient pathways and improved NICE guidance adherence.

ADVANCES IN KNOWLEDGE

GP-led CTCA is a feasible and safe pathway for patients without pre-existing CAD referred to RACPC, reducing hospital encounters required and may accelerate time to diagnosis. This approach may have implications and opportunities for other healthcare pathways.

Assessing splenic switch-off in Adenosine stress CMR for patients with atrial fibrillation: a propensity-matched study

OBJECTIVES

Splenic switch-off (SSO) is a validated indicator of adequate vasodilator stress unique to adenosine stress cardiac MR (CMR). Patients in atrial fibrillation (AF) may have a reduced adenosine response due to lower hyperaemic coronary flow reserve and may achieve SSO less frequently versus sinus rhythm (SR).

METHODS

1100 stress CMR studies were identified from a clinical CMR database (2016-2021). 70 patients in AF were propensity score matched to a SR group for age, sex, and body mass index. The adenosine dose administered, symptoms, heart-rate change and scan result were recorded. SSO was evaluated subjectively and semi-quantitatively via changes in splenic and myocardial signal intensity (SI) from rest to stress.

RESULTS

SSO occurred significantly less frequently in AF than SR (34/70 [49%] vs 53/70 [76%], p = 0.003). Semi-quantitative assessment supported this, with a smaller splenic SI difference between stress and rest in AF vs SR (median splenic stress:rest peak SI ratio 0.92 [IQR:0.61-1.11] vs 0.56 [IQR:0.45-0.75], p < 0.001). A heart-rate increase >10 bpm predicted visual SSO in SR but not AF. Fewer patients in AF than SR had inducible ischaemia (9/70 [13%] vs 17/69 [25%], p = 0.058). This difference was not driven by inducible ischaemia rates in patients who did not achieve SSO (6/36 [17%] AF vs 4/17 [24%] SR, p = 0.403).

CONCLUSIONS

SSO occurs significantly less frequently with AF. This may risk the under diagnosis of inducible ischaemia and requires further assessment.

ADVANCES IN KNOWLEDGE

SSO, a validated marker of adequate stress in CMR, occurs significantly less frequently in the presence of AF, risking a suboptimal functional assessment of coronary disease.

Coronary CT angiography derived pericoronary inflammation and bespoke cardiovascular risk prediction in the lipid clinic: beyond the calcium score

Background

Dyslipidaemia promotes atherosclerosis. Genetic dyslipidaemias, Familial Hypercholesterolaemia (FH) being the most common, are associated with heightened risk of coronary artery disease (CAD) and premature major adverse cardiovascular events (MACE). However, this risk is both heterogeneous and modifiable with treatment.

CT coronary imaging can identify subclinical atherosclerosis, enabling personalised risk stratification and treatment targets. Coronary artery calcium scoring (CACS) is current first-line in European guidelines for asymptomatic patients. However, calcification occurs late in CAD pathogenesis and CACS has low specificity in young patients with severe FH. CT coronary angiography (CTCA) assesses non-calcific plaque and high-risk plaque (HRP) features unappreciable with CACS. Additionally, the pericoronary fat attenuation index (FAI) measures inflammation on routine CTCA and is the strongest non-invasive imaging biomarker of risk of fatal MI.

Purpose

To quantify and compare the reclassification of subclinical atherosclerosis burden in Lipid Clinic patients assessed via CACS vs CTCA with FAI analysis.

Methods

Analysis of a prospectively maintained clinical database of asymptomatic Lipid Clinic patients with both CACS and CTCA imaging from May 2019 to December 2020. CACS was reported with the standardised Agastston criteria and compared with (i) the CTCA-derived Coronary Artery Disease – Reporting and Data System (CAD RADS) grading of anatomical stenosis, including a modifier for HRP features, and (ii) FAI analysis. Significance was defined as two-tailed p75th percentile vs age and sex matched controls) was seen in 6/27 (22%) patients with none to mild calcification on CACS and 6/28 (21%) patients with none to mild CAD on CTCA, of whom 3/7 (43%) had HRP. High FAI was seen in all groups of calcification severity and CAD RADS score (Figure 2). The proportion with high FAI was higher in CAD RADS 0 vs CAD RADS 4, and CACS severity was not associated with level of inflammation (p=0.94).

High FAI was observed in 16% of patients on treatment, suggesting treatment failure. This included patients with CACS ranging from 0 to severe (&gt;400), and CAD RADS of minimal (1) to severe (4).

Conclusion

CTCA re-stratifies CAD presence and severity vs CACS in a high-risk, asymptomatic patient group and identified a high proportion of patients with HRP features. FAI provides incremental value in identification of patients at risk of future MACE regardless of CACS grade, including patients without evidence of overt CAD. Identifying high FAI on treatment may imply treatment failure.

Funding Acknowledgement

Type of funding sources: None.

CT coronary angiography-guided cardiovascular risk screening in asymptomatic patients: is it time?

Cardiovascular disease (CVD) is the leading cause of death in the UK, whilst millions live with various forms of the disease. Coronary artery disease constitutes a significant portion of this morbidity and mortality, and is the leading cause of premature death. Increasing focus is thus being placed on the optimisation of CVD prevention, where risk screening plays a key role. Indeed, the decline in age-adjusted cardiovascular mortality achieved up to now has been largely attributed to primary preventative therapies (e.g., statins) introduced earlier in the disease process. National initiatives exist to improve cardiovascular health at a population level, but in its current form, CVD screening at the individual level is predominantly undertaken using multivariate risk scores based on population-based data. These have multiple innate flaws, highlighted in this review. Non-invasive imaging plays a key role in the screening of other disease processes, helping to personalise the screening process. Although the coronary artery calcium score as a screening tool has a role in national and international guidance, whether a shift to screening with computed tomography coronary angiography (CTCA) is now appropriate is open for discussion. Image acquisition techniques continue to improve with reducing radiation exposure and an ever-expanding evidence-base for additional prognostic data offered by CTCA. This enables the potential identification of sub-clinical atherosclerosis, including with novel artificial intelligence techniques. This review aims to report current guidelines regarding cardiac CT imaging in the asymptomatic primary prevention setting, advances in various CT technologies and future opportunities for progress in this field.

FFRCT and Invasive Coronary Angiography – assessing concordance in an unselected UK real world population

Background/Introduction

CT coronary angiography (CTCA) Fractional Flow Reserve (FFRCT) is a key investigation in chronic coronary syndrome (CCS) guidelines. FFR calculated from CTCA may help improve CTCA specificity for flow limiting disease, preventing unnecessary invasive coronary angiography (ICA).

Purpose

To (1) assess the treatment planning potential of FFRCT by determining the concordance of FFRCT with an ICA +/− invasive physiological assessment for the detection of flow limiting CAD in a real world NHS setting and (2) concordance sub-analysis of concordance of invasive iFR and FFRCT.

Methods

A single-centre retrospective analysis of a prospectively maintained clinical CTCA database. We identified patients with CCS who had CTCA FFRCT and subsequent ICA from August 2018 to January 2021. Concordance was assessed on a per patient and per vessel basis (major epicardial vessels: left main stem [LMS], left anterior descending artery [LAD], circumflex [LCx], right coronary artery [RCA]). Two non-invasive ischaemia thresholds were examined an FFRCT ≤0.8 and &lt;0.75 (2 cm distal to stenosis). This was compared to a clinical ICA assessment where a flow limiting lesion was defined as a stenosis &gt;70% (or &gt;50% in the LMS) and/or an end vessel iFR ≤0.89 / FFR ≤0.8. All vessels that underwent an iFR, at the interventionists discretion, were then assessed relative to their end-vessel FFRCT.

Results

565 patients had a CTCA with FFRCT and 164 patients had a subsequent ICA and were suitable for analysis. On a per patient basis 69% of those referred to ICA with an FFRCT ≤0.8 of at least one major epicardial vessel had any flow limiting CAD at ICA. With an FFRCT &lt;0.75 this was 73%. Table 1 illustrates the per vessel concordance.

A total of 120 vessels were included in the iFR subsection analysis. The mean FFRCT was 0.71 (±0.13) and mean iFR was 0.89 (±0.1). Accuracy was 54% (95% CI 45–63%) with a sensitivity of 89% (95% CI 76–96%), specificity 32% (95% CI 22–44%), positive predictive value 45% (95% CI 40–50%) and negative predictive value of 83% (95% CI 66–92%). A Pearson's correlation coefficient of 0.23 was found.

Conclusion

This study demonstrated that the negative predictive value of FFRCT was excellent, including importantly for LMS analysis. The specificity on a per vessel basis was good with the exception of the LAD assessment. This may have implications for interventional planning with this imaging modality. FFRCT correlated poorly with invasive iFR in this subsection analysis although selection bias may be contributing. There remains a significant proportion of patients referred for an ICA where no flow limiting CAD is found.

Funding Acknowledgement

Type of funding sources: None. Table 1. Per vessel concordance analysis of potential flow limiting FFRCT relative to clinical ICA findings. Analysed with an ischaemia threshold of FFRCT ≤0.80 and &lt;0.75. PPV = Positive Predictive Value. NPV = Negative Predictive Value.

Study of Bonding Formation between the Filaments of PLA in FFF Process

Fused filament fabrication (FFF) is an additive manufacturing (AM) process that provides physical objects commonly used for modeling, prototyping and production applications. The major drawback of this process is poor mechanical property due to the porous structure of final parts. This process requires careful management of coalescence phenomenon. In this paper, the major influencing factors during the FFF processing of poly(lactic acid) (PLA) were investigated experimentally and with a numerical model. It has been shown that the polymer temperature has a significant effect on the rheological behavior of PLA, especially on the adhesion of the filaments. An experimental set-up has been placed in the machine to have the cyclic temperature of the filament. A variation of the polymer temperature influences process parameters such as feed rate, temperature of the nozzle and temperature of the platform. The results showed that the amount of polymeric coalescence (neck growth) rises when increasing the feed rate, the nozzle temperature, and the platform temperature. A model to predict the neck growth is proposed. It predicts a lower amount of neck growth value than obtained experimentally. This difference has been explained as the effect of other phenomena, such as polymer relaxation time, pressure of the nozzle and especially cyclic temperature which is not taken into account in the model.

Discharge after primary angioplasty at 24 h: feasible and safe or a step too far?

Current clinical practice regarding surveillance period and length of hospital stay after an ST elevation myocardial infarction is very variable among different countries and hospitals. In general, there has been a significant reduction in length of stay overall, which is mainly due to the increasing use of primary percutaneous coronary intervention. Length of stay after a ST elevation myocardial infaction, which is a rather common event, has a major impact on health care costs and patients' quality of life. We try to evaluate how far we could push the limits.

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.

Diabetic cardiomyopathy--a distinct disease?

Diabetic individuals have a significantly increased likelihood of developing cardiovascular disease. Whilst part of this association is explained by the presence of concomitant risk factors, large epidemiological studies have consistently reported diabetes as a strong risk factor for the development of heart failure after adjusting for such covariates. This has resulted in the notion that there is a distinct cardiomyopathy specific to diabetes, termed 'diabetic cardiomyopathy'. The natural history is characterized by a latent subclinical period, during which there is evidence of diastolic dysfunction and left ventricular hypertrophy, before overt clinical deterioration and systolic failure ensue. These clinical findings have been supported by a growing body of experimental data which support the notion that diabetes inflicts a direct insult to the myocardium, with cellular, structural and functional changes manifest as the diabetic myocardial phenotype. Several of these mechanisms appear to work in unison, forming complicated reciprocal pathways of disease. Reactive oxygen species and alterations in intracellular calcium homeostasis appear to play significant roles in many of these mechanisms. Determining the hierarchy of this cascade of disease will allow identification of the pathological trigger most responsible for disease. Translational research in this field is currently hindered by a lack of clinical studies and intervention trials specifically in patients with diabetic cardiomyopathy. Future clinical and experimental studies of accurate models of diabetic cardiomyopathy should help to define the true aetiology and lead to the development of specific pharmacotherapies for this condition, ultimately reducing the increased cardiovascular morbidity and mortality in diabetic patients.

Myocardial infarction associated with the administration of intravenous ephedrine and metaraminol for spinal-induced hypotension

A 31-year-old female with no risk factors for cardiac disease suffered a peri-operative myocardial infarction during an elective gynaecological procedure under spinal anaesthesia. The timing and nature of cardiac symptoms suggest that the myocardial infarction was caused by coronary artery vasospasm secondary to ephedrine and/or metaraminol, which were administered to treat spinal-induced hypotension. We review the recent literature and case reports on myocardial infarction attributed to sympathomimetic drugs, and recommend the use of sublingual or intravenous nitrates when signs or symptoms of coronary arterial vasospasm become evident during their use.

Acute streptococcal myopericarditis mimicking myocardial infarction

A 25-year-old man who had recurrent sore throats presented with sharp central chest pain 5 hours after starting penicillin for tonsillitis. Electrocardiogram (ECG) revealed ST-segment elevation in leads I and aVL with reciprocal ST depression in lead III (Fig. 1). Troponin I was measured as 33 microg/L (normal range, b0.1 microg/L), and C-reactive protein (CRP) was 127 (normal range b10). Echocardiogram revealed a nondilated well-contracting left ventricle, and cardiac catheterization revealed normal coronary arteries. A diagnosis of acute myopericarditis was made, and he was treated with moxifloxacin. Throat swabs grew Lancefield group A Streptococcus. Over subsequent days, his symptoms and ECG changes resolved, and he was discharged on longterm prophylactic penicillin.

Advising patients on dealing with acute chest pain

Instructions about using GTN and when to call an ambulance need to be clearer

In vitro biological evaluation of β–TCP/HDPE—A novel orthopedic composite: A survey using human osteoblast and fibroblast bone cells

Beta-tricalcium phosphate reinforced high density polyethylene (beta-TCP/HDPE) was prepared to simulate bone composition and to study its capacity to act as bone tissue. This material was produced by replacing the mineral component and collagen soft tissue of the bone with beta-TCP and HDPE, respectively. The biocompatibility of the composite samples with different volume fractions of TCP (20, 30 and 40 vol %) was examined in vitro using two osteoblast cell lines G-292 and Saos-2, and also a type of fibroblast cell isolated from bone tissue, namely human bone fibroblast (HBF) by proliferation, and cell adhesion assays. Cell-material interaction with the surface of the composite samples was examined by scanning electron microscopy (SEM). The effect of beta-TCP/HDPE on the behavior of osteoblast and fibroblast cells was compared with those of composite and negative control samples; polyethylene (PE) and tissue culture polystyrene (TPS), respectively. In general, the results showed that the composite samples containing beta-TCP as reinforcement supported a higher rate of proliferation by various bone cells after 3, 7, and 14 days of incubation compared to the composite control sample. Furthermore, more osteoblast cells were attached to the surface of the composite samples when compared to the composite control samples after the above incubation periods (p < 0.05), while in the case of HBF an equal or even higher number of cells adhered to PE was observed. The number of adhered osteoblast cells was almost equal and in some days even higher than the number of adhered cells on negative control sample, while in the case of fibroblast this difference was significantly higher than TPS (p < 0.05). Adhered cells presented a normal morphology by SEM and many of the cells were observed to be undergoing cell division. These findings indicate that beta-TCP/HDPE composites are biocompatible, nontoxic, and act to stimulate proliferation and adhesion of the cells, whether osteoblast or fibroblast.

Flecainide cardiotoxicity precipitated by electrolyte imbalance. Caution with thiazide diuretics

A man presented with recurrent syncope, weakness and fatigue. His ECG showed marked QRS widening and he had gross hyponatraemia and hypokalaemia. His medications included bendroflumethiazide (long term) and flecainide (started 2 months previously). This presentation was consistent with flacainide cardiotoxicity exacerbated by electrolyte disturbance. The syncopal episodes probably represented life-threatening arrhythmias. The ECG and symptoms resolved completely once the electrolytes were corrected. Increased cardiotoxicity with hypokalaemia is documented, but not widely recognised. Hyponatraemia-induced flecainide cardiotoxicity has not been documented. The clinical effects of flecainide are due to use-dependent block of sodium channels. There are reports that support the use of hypertonic sodium salts to reverse flecainide toxicity via antagonism at the receptor. By this rationale, hyponatraemia would lead to Flecainide toxicity. Flecainide has been shown to reduce salt absorption in animal bowel. It is possible that in combination with bendroflumethiazide it acted synergistically to produce profound electrolyte disturbance. Flecainide cardiotoxicity has a significant mortality and can present non-specifically. Thus, early recognition is essential. This case demonstrates the importance of strict electrolyte control in patients who are on flecainide. We would discourage concomitant use of flecainide and bendroflumethiazide.

Acute coronary syndrome

Glycoprotein IIb/IIIa inhibitors are still underused, especially in patients at high risk

Effect of reinforcement particle size onin vitro behavior of β-tricalcium phosphate-reinforced high-density polyethylene: A novel orthopedic composite

Beta-tricalcium phosphate-reinforced high-density polyethylene (beta-TCP/HDPE) is a new biomaterial, which was made to simulate bone composition and study its capacity to act like bony tissues. This material was produced by replacing mineral component and collagen soft tissue of bone with beta-TCP and HDPE, respectively. The biocompatibility of composite samples with different volume fractions of TCP (20, 30, and 40 vol %) and two different particle sizes (80-100 and 120-140 mesh size) was examined in vitro using the osteoblast cell line G-292 by proliferation, alkaline phosphatase (ALP) production, and cell adhesion assays. Cell-material interaction on the surface of the composites was observed by scanning electron microscopy (SEM). The effect of beta-TCP particle size on behavior of the osteoblast cell line was compared between two groups of the composite samples containing smaller and larger reinforcement particle sizes as well as with those of a negative control. In general, results showed that the composite samples containing larger particles supported a higher rate of proliferation and ALP production by osteoblast cells after 3, 7, and 14 days of incubation compared to the composite samples with smaller particle size and control. Furthermore, more cells were attached to the surface of composite samples containing larger particle size when compared to the smaller particle size composites (p<0.05). This number was nearly equal with numbers adhered on negative control [tissue culture polystyrene (TPS)] and significantly higher in comparison with composite control [polyethylene (PE)] (p<0.05). Adhered cells presented a normal morphology by SEM and many of the cells were seen to be undergoing cell division. These findings indicate that beta-TCP/HDPE composites are biocompatible, nontoxic, and in some cases, act to stimulate proliferation of the cells, ALP production, and cell adhesion when compared to the control counterparts. Furthermore, beta-TCP/HDPE samples with larger reinforcement particle size were shown to possess better biological properties.

The effect of partially stabilized zirconia on the biological properties of HA/HDPE composites in vitro

The effect of partially stabilized zirconia (PSZ) on the biological properties of the hyroxyapatite - high density polyethylene (HA/HDPE) composites was studied by investigating the simultaneous effect of hydroxyapatite and PSZ volume fractions on the in vitro response of human osteoblast cells. The biocompatibility of composite samples with different volume fraction of HA and PSZ powders was assessed by proliferation, alkaline phosphatase (ALP) and cell attachment assays on the osteoblast cell line (G-292) in different time periods. The effect of composites on the behavior of G-292 cells was compared with those of HDPE and TPS (Tissue Culture Poly Styrene as negative control) samples. Results showed a higher proliferation rate of G-292 cells in the presence of composite samples as compared to the HDPE sample after 7 and 14 days of incubation period. ALP production rate in all composite samples was higher than HDPE and TPS samples. The number of adhered cells on the composite samples was higher than the number adhered on the HDPE and TPS samples after the above mentioned incubation periods. These findings indicates that the addition of PSZ does not have any adverse affect on the biocompatibility of HA/HDPE composites. In fact in some experiments PSZ added HA/HDPE composites performed better in proliferation, differentiation and attachment of osteoblastic cells.

In vitro evaluation of biocompatibility of beta-tricalcium phosphate-reinforced high-density polyethylene; an orthopedic composite

Beta-tricalcium phosphate-reinforced high-density polyethylene (beta-TCP/HDPE) is a new biomaterial which was made as a copy of bone composition with the aim of replacement of bony tissues. The composite samples were prepared using medical grade TCP powder and granular polyethylene. The raw materials were first compounded and the resulting composite preforms were compression molded into desired shape. The biocompatibility of composite samples with different volume fractions of TCP (20, 30, and 40 vol %) was assessed by proliferation, alkaline phosphatase (ALP), and cell adhesion assays using G-292 osteoblast cells. Cell-material interaction on the surface of the composites was observed by scanning electron microscopy (SEM). The effect of beta-TCP/HDPE on the behavior of G-292 cells was compared with those of a composite and a negative control samples. Results showed the composite samples had a higher proliferation rate of G-292 cells in the presence of composite samples as compared to the composite control sample after 3, 7, and 14 days of incubation period. ALP production after incubation in the presence of composite samples was seen to peak on the day 7. The number of adhered cells on the composite samples was higher than the numbers adhered on composite and negative control samples after the above incubation periods. Morphology investigation of adhered cells by SEM indicated a normal morphology and also many of the cells were in the process of cell division. The above results indicate that beta-TCP/HDPE samples are biocompatible, nontoxic, and in some cases show an increase in the proliferation rate of the cells, ALP production, and cell adhesion as compared to the control counterparts.

The malignant epidemic--changing patterns of trauma

OBJECTIVES AND SETTING

The worldwide burden of trauma is increasing, but is unequally distributed between nations. Trauma in South Africa targets the young and productive in society and imposes a major burden on the health infrastructure. We undertook a review of injury trends among patients attending the Johannesburg Hospital Trauma Unit (JHTU) and the Johannesburg Medicolegal Laboratory (JMLL) in order to document the evolution in patterns of trauma over a 17-year period of great social and political change.

DESIGN, SUBJECTS AND OUTCOME MEASURES

This was a retrospective review of all priority-one patients attending the JHTU from January 1985 to December 2001. The JHTU trauma database was used to retrieve information on patient demographics, wound mechanism and injury severity. The database at the JMLL, maintained since 1996, was examined and the manner and place of death were analysed.

RESULTS

The JHTU has seen an unprecedented increase in the number of trauma patients over the last 17 years. The patients' demographic profiles have altered and injury is now predominantly due to interpersonal violence. Unnatural deaths examined at the JMLL have declined by 19% since 1996; however, the proportion of those deaths due to gunshot wounds has risen.

CONCLUSIONS

The social and political changes in South Africa in recent years have led to changes in the injury profiles seen at the JHTU. Part of the increase can be explained by desegregation and a reduction in the provision of local hospital services; however, the impact of urbanisation within South Africa, cross-border migration and the high incidence of substance abuse are recognised. Evidence supports the implementation of legislative, environmental, social and behavioural interventions to contain and reduce the incidence and impact of violence and injury. Concerted efforts must be made at all levels to curb South Africa's trauma epidemic.