COVID-19 and Climate Change: Re-thinking Human and Non-Human in Western Philosophy

The pre-conditions and the effects of the COVID-19 pandemic are inter-connected with those of climate change, prompting reflection on how to re-think the relations between human and non-human on a changing planet. This essay considers that issue with reference to the contrasts between the philosophies of Descartes and Spinoza, who offered radically different approaches to the conceptualization of human presence in Nature.

Invariant NKT cells metabolically adapt to the acute myeloid leukaemia environment

Acute myeloid leukaemia (AML) creates an immunosuppressive environment to conventional T cells through Arginase 2 (ARG2)-induced arginine depletion. We identify that AML blasts release the acute phase protein serum amyloid A (SAA), which acts in an autocrine manner to upregulate ARG2 expression and activity, and promote AML blast viability. Following in vitro cross-talk invariant natural killer T (iNKT) cells become activated, upregulate mitochondrial capacity, and release IFN-γ. iNKT retain their ability to proliferate and be activated despite the low arginine AML environment, due to the upregulation of Large Neutral Amino Acid Transporter-1 (LAT-1) and Argininosuccinate Synthetase 1 (ASS)-dependent amino acid pathways, resulting in AML cell death. T cell proliferation is restored in vitro and in vivo. The capacity of iNKT cells to restore antigen-specific T cell immunity was similarly demonstrated against myeloid-derived suppressor cells (MDSCs) in wild-type and Jα18^-/- syngeneic lymphoma-bearing models in vivo. Thus, stimulation of iNKT cell activity has the potential as an immunotherapy against AML or as an adjunct to boost antigen-specific T cell immunotherapies in haematological or solid cancers.

Evaluation of right ventricular contractile reserve in healthy subjects using stress echocardiography

Funding Acknowledgements

Type of funding sources: None.

Background

The assessment of right ventricular (RV) systolic functional augmentation in healthy subjects is not well described. The objective of this study was to evaluate normal augmentation of RV systolic functional parameters in relation to maximum predicted oxygen uptake (VO2) during stress echocardiography in healthy adults.

Methods

  Untrained healthy volunteers were recruited prior starting their first time London Marathon and underwent cardiopulmonary exercise test with echocardiography focussed on left ventricular assessment.  Patients with satisfactory RV windows were included in this analysis. 20 participants with good RV delineation were evaluated retrospectively at baseline and at peak level of exercise. We defined RV systolic function by tricuspid lateral annular systolic velocity (RVS’) using Doppler tissue imaging, Tricuspid Annular Plane Systolic Excursion (TAPSE) using M-mode echocardiography, and Fractional Area Change (FAC) using 2D echocardiography to calculate the percentage of change in RV area between systole and diastole. All parameters were evaluated at baseline and at peak stress.

Results

There was statistically significant augmentation of all RV systolic functional parameters between baseline and peak stress (10.3 ± .8 vs 16.4 ± .7 cm/s, p <.000), (21 ± 2.6 vs 32 ± 3.3, mm, p <.000) and (41 ± 2.7, % vs 55 ± 5.1, %, p<.000) for RVS’, TAPSE and FAC respectively. At peak stress, RVS’ increased by 59 ± 11.1, %, TAPSE by 53 ± 15.4, %, and FAC by 34 ± 11.8, %. Mean peak VO2 was 107 ± 17, %. The augmentation of RV longitudinal function showed moderate correlation with peak VO2 throughout exercise for the RVS’ and TAPSE (r= .54, p 0.001), (r=.45, p0.04) respectively, and this was not observed in FAC (r=.15, p>.05).

Conclusion

In normal individuals, we have demonstrated that the RV augments by 59% for RVS’, 53% for TAPSE, and 34% for FAC. Longitudinal RV augmentation by RVS’ and TAPSE was correlated with maximum exercise capacity suggesting that these parameters could be able to predict VO2 peak values in larger context. Abstract Figure.

Non-invasive assessment of ventriculo-arterial coupling using aortic wave intensity analysis combining central blood pressure and phase-contrast cardiovascular magnetic resonance

BACKGROUND

Wave intensity analysis (WIA) in the aorta offers important clinical and mechanistic insight into ventriculo-arterial coupling, but is difficult to measure non-invasively. We performed WIA by combining standard cardiovascular magnetic resonance (CMR) flow-velocity and non-invasive central blood pressure (cBP) waveforms.

METHODS AND RESULTS

Two hundred and six healthy volunteers (age range 21-73 years, 47% male) underwent sequential phase contrast CMR (Siemens Aera 1.5 T, 1.97 × 1.77 mm2, 9.2 ms temporal resolution) and supra-systolic oscillometric cBP measurement (200 Hz). Velocity (U) and central pressure (P) waveforms were aligned using the waveform foot, and local wave speed was calculated both from the PU-loop (c) and the sum of squares method (cSS). These were compared with CMR transit time derived aortic arch pulse wave velocity (PWVtt). Associations were examined using multivariable regression. The peak intensity of the initial compression wave, backward compression wave, and forward decompression wave were 69.5 ± 28, -6.6 ± 4.2, and 6.2 ± 2.5 × 104 W/m2/cycle2, respectively; reflection index was 0.10 ± 0.06. PWVtt correlated with c or cSS (r = 0.60 and 0.68, respectively, P < 0.01 for both). Increasing age decade and female sex were independently associated with decreased forward compression wave (-8.6 and -20.7 W/m2/cycle2, respectively, P < 0.01) and greater wave reflection index (0.02 and 0.03, respectively, P < 0.001).

CONCLUSION

This novel non-invasive technique permits straightforward measurement of wave intensity at scale. Local wave speed showed good agreement with PWVtt, and correlation was stronger using the cSS than the PU-loop. Ageing and female sex were associated with poorer ventriculo-arterial coupling in healthy individuals.

Pulsatile and resistive systolic loads as determinants of left ventricular remodelling after physical training

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation Barts Cardiovascular Biomedical Research Centre

onbehalf

The Marathon Study Consortium

Introduction

Cardiovascular function depends on the inter-relation between heart and vasculature.  The contribution of aorta and peripheral vessels to the total systolic load of the left ventricle (LV) can be represented respectively by a "pulsatile" and a "resistive" component. We sought to understand their interrelation by exploring how LV remodelling occurred with altered load associated with an external stimulus (training). Methods: 237 untrained healthy male and female subjects volunteering for their first-time marathon were recruited. At baseline and after 6 months of unsupervised training, race completers underwent 1.5T cardiac magnetic resonance, brachial and non-invasive central blood pressure assessment. For analysis, runners were divided into 4 groups according to the variation (positive versus null or negative) in Total Arterial Compliance Index (TACi), representing the pulsatile component of the LV load, and in Systemic Vascular Resistance Index (SVRI), representing the resistive component of the LV load. Results: 138runners (age 21-69 years; F: 51%) completed the race. Data are reported for each variable as Δ mean [95% Confidence Interval]. In the whole cohort, training was associated with a small increase in LV mass index (+3g/m2, [0, 6 g/m2]), indexed LV end-diastolic volume (EDVi) (+3ml/m2, [-2, 5 3ml/m2]), in LV mass/LVEDV ratio (+0.02g/ml, [0.00, 0.04 g/ml]) and in TACi (+0.02ml/m2, [0.02, 0.38 ml/m2]). SVRi mildly fell (-43dyn·s/cm2[-103, 17dyn·s/cm2]). TACi increase was associated with LVEDVi increase and no change in LV mass/EDV (eccentric remodelling). On the other hand, both TACi reduction and SVRi increase were associated with increase in LV mass/EDV and no significant change in LVEDVi (concentric remodelling). A similar increase in LV mass was observed in all groups. See Table. Conclusion: Cardiac remodelling observed after mild, medium term, unsupervised training seems to be related to the modifications of aorta and peripheral vessels. In particular, a reduction in pulsatile load seems associated with eccentric LV remodelling, while an increase in both pulsatile and resistive with concentric LV remodelling. Further research is needed to understand the interaction between TACi and SVRi.

Table 1 LV EDVi (ml/m2) LV mass index (g/m2) LV mass/EDV TACi increase (n = 75) +4 [0, 9] +3 [0, 7] 0 [-0.03, 0.03] TACi decrease (n = 62) -1 [-6, 4] +3 [0, 8] 0.04 [0.01, 0.07] SVRi increase (n = 63) 0 [-4,4] +3 [0, 7] +0.03 [0, 0.06] SVRi decrease (n = 73) +3 [-3, 7] +3 [-1, 6] +0.01 [-0.02, 0.04]

Myocardial fibrosis quantification by cardiac CT predicts outcome in severe aortic stenosis

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Background

Myocardial extracellular volume (ECV) increases with fibrosis, oedema or infiltration. ECV by CMR predicts all-cause and cardiovascular mortality in severe AS after valve intervention. Previous studies have shown that ECV can be reliably quantified by computed tomography (ECVCT), but these studies have not differentiated between ECV elevation due to fibrosis or cardiac amyloid deposition (13-16% of patients with severe AS). 

Purpose

We hypothesised that ECVCT quantification, performed as part of a transcatheter aortic valve implantation (TAVI) work-up CT, predicts survival in patients with severe AS without cardiac amyloid (lone AS).

Methods

Patients aged ≥75, with severe AS, referred for TAVI at Barts Heart Centre (as part of ATTRact-AS (NCT03029026)) underwent CT as part of their clinical work-up. All patients had 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scintigraphy and those with a positive result were excluded.  CT was performed on a 128-slice dual-source 3rdgeneration scanner (Siemens Somatom FORCE) and ECVCT was acquired during the TAVI work-up CT using additional pre- and 3-minute post-contrast ‘axial shuttle mode’ acquisitions (no additional contrast).  ECVCT was calculated from the Hounsfield units (HU) and a venous haematocrit (HCT): ECVCT = (1-HCT) x (ΔHUmyo/ΔHUblood).

Results

Following exclusion of 16 patients with cardiac uptake on DPD, 93 patients (41% male, aged 85 ± 5 years) were included in the study.  All patients had severe AS (AV Vmax 4.12 ± 0.63m/s, mean AV gradient 42 ± 14mmHg, AVA 0.71 ± 0.23cm2). The mean HCT was 0.38 ± 0.04 and total dose-length product for additional research scans was 364 ± 41 mGy.cm. 76 patients (82%) underwent TAVI. ECVCT was 32 ± 3% in the entire cohort, which we then split into those with a ‘higher’ ECVCT (&gt;34%, n = 23, representing the highest quartile) and those with a ‘lower’ ECVCT (≤34%, n = 70, representing the lower quartiles). Over a median follow-up of 25 months (IQR 17-34 months) there were 27 deaths (29%), of whom 11 did not undergo TAVI (41%). There were 10 deaths in the 23 patients (44%) with a higher ECVCT, compared to 17 in the 70 patients (24%) with a lower ECVCT (p = 0.03, figure 1). This mortality difference remained significant when those patients who did not undergo TAVI were excluded (p = 0.03).

Conclusions

Myocardial fibrosis quantified by ECVCT is associated with a significantly worse prognosis in lone AS, even after patients with AS-amyloid are excluded. ECVCT can be performed as a simple addition to the TAVI work-up CT and provides additional prognostic information.

Abstract Figure.

Myocardial work analysis in screening of familial dilated cardiomyopathy

Introduction

Early detection of affected family relatives of patients with dilated cardiomyopathy (DCM) is essential in order to guide follow up, outcomes and initiate early treatment. Myocardial work analysis is a novel method which integrated strain imaging and blood pressure and has the potential to identify patients with subclinical disease.

Purpose

We analysed myocardial work in family relatives of DCM patients with positive genotype but negative phenotype in order to identify whether myocardial work can identify early changes.

Methods

Seventy-four family relatives of DCM patients attending for screening were examined. All individuals were asymptomatic with either positive (45/74, G+) or negative (29/74, G-) genotype and no echocardiographic evidence of left ventricular dilatation or systolic impairment. Non-invasive myocardial work analysis using two-dimensional (2D) speckle tracking echocardiography was analysed. Global longitudinal strain (GLS) was measured by the same vendor specific software used for myocardial work analysis. Left ventricular (LV) ejection fraction (EF) was measured with the Simpson's biplane method. The peak systolic arm cuff blood pressure (BP) measurement at the time of echocardiography was used for the myocardial work study.

Results

In total we included 74 individuals (37±15 years old, 50.7% women) with mean systolic and diastolic BP of 121.3±14 and 73.2±10 mmHg respectively, mean EF was 58±5% and mean GLS at 18.4±2.5%.

G+ individuals had pathogenic and very likely pathogenic mutations in 8 different genes (TTN, BAG3, DSP, FLNC, LMNA, DMD, RBM20, TPM1). There was no difference in age, systemic hypertension, diabetes or medical treatment between the 2 groups.

No significant difference was found among G+ and G- individuals in mean systolic and diastolic BP (121.2±14.7 vs 121.2±15.2 mmHg), mean EF (57.3±5 vs 59.1±4%), GLS (−18.2±1.5 vs −18.6±2.9%), mean global work index (1818±403 vs 1928±295 mmHg%) and global constructive work (2192±464 vs 2260±318 mmHg%).

However, we found significant reduction of the global work efficiency (GWE) with a GWE of 94.4±2.7% in the G+ versus 95.9±1.6% in the G- individuals (p 0.02). Moreover, the global wasted work (GWW) was increased in the G+ with a GWW of 111±58 mmHg% versus 82±41 mmHg% in the G- individuals (p 0.03).

Conclusion

DCM gene carriers show, early on, decreased myocardial work efficiency and increased wasted work compared to unaffected family members, which appears to be earlier than other parameters such as EF and GLS. Myocardial work analysis could potentially recognize individuals showing early cardiac involvement and guide closer follow up and early initiation of treatment.

Funding Acknowledgement

Type of funding source: None

Metabolic engineering against the arginine microenvironment enhances CAR-T cell proliferation and therapeutic activity

Hematological and solid cancers catabolize the semiessential amino acid arginine to drive cell proliferation. However, the resulting low arginine microenvironment also impairs chimeric antigen receptor T cells (CAR-T) cell proliferation, limiting their efficacy in clinical trials against hematological and solid malignancies. T cells are susceptible to the low arginine microenvironment because of the low expression of the arginine resynthesis enzymes argininosuccinate synthase (ASS) and ornithine transcarbamylase (OTC). We demonstrate that T cells can be reengineered to express functional ASS or OTC enzymes, in concert with different chimeric antigen receptors. Enzyme modifications increase CAR-T cell proliferation, with no loss of CAR cytotoxicity or increased exhaustion. In vivo, enzyme-modified CAR-T cells lead to enhanced clearance of leukemia or solid tumor burden, providing the first metabolic modification to enhance CAR-T cell therapies.

623 Short-term reversed remodeling post aortic valve intervention

Background

LV remodeling in AS can cause LV hypertrophy, interstitial fibrosis and reduced contractility. SAVR or TAVI are the mainstay treatment for symptomatic severe AS. Speckle tracking has the potential to detect early signs of reverse cardiac remodeling but such LV deformation data post-SAVR/TAVI is currently lacking.

Aim

To assess the early impact of LV unloading post-TAVR/SAVR using STE.

Methods

This prospective single-center study recruited 122 patients with varying degrees of AS who underwent resting transthoracic echocardiography with offline speckle-tracking. During the follow-up period, 50 patients underwent TAVI and 15 had SAVR.

Results

Patients were followed-up for a period of 4 ± 2 weeks post-intervention. Table 1 summaries the echocardiographic findings of patients pre- and post-intervention. AV peak velocity and mean pressure gradient dropped significantly immediately after intervention in both groups. AV intervention resulted in early improvements in all myocardial deformation parameters (Figure 1). There was a significant improvement in GLS and GRS irrespective of the intervention type. While SAVR led to a significant early improvement in GCS.

Conclusion

AV Intervention in severe symptomatic AS translates into an immediate and measurable improvement in LV deformation parameters. To our knowledge this is the first echocardiographic evidence of reverse remodeling early after SAVR and TAVI.

Table 1 TAVI (n = 50) SAVR (n = 15) Variables Pre Post P* value Pre Post P* value P value┼ AV vel.(m/s) 4.4 ± 0.8 2.2 ± 0.5 &lt;0.001 4.5 ± 0.8 2.2 ± 0.5 &lt;0.001 NS AV mPG (mmHg) 44.3 ± 16.2 9.7 ± 3.9 &lt;0.001 44.6 ± 19.2 9.8 ± 4.8 &lt;0.001 NS GLS (%) -10.9 ± 3.6 -13.9 ± 3.1 &lt;0.001 -13.7 ± 4.5 -17.7 ± 3.9 0.002 NS GCS (%) -29.2 ± 9.1 -32 ± 9.5 NS -28.6 ± 9.8 -34.9 ± 5.1 0.032 NS GRS (%) 42.0 ± 15.1 47.2 ± 13 0.024 34.7 ± 12.5 41.4 ± 9.9 0.04 NS EDV (ml) 87.29 ± 55.3 89.8 ± 38.6 NS 104.3 ± 25.1 83.2 ± 41.9 NS NS ESV (ml) 45.1 ± 39.4 36.6 ± 29.1 NS 42.8 ± 17.7 28.6 ± 18.6 0.03 NS SV (ml) 59.7 ± 23.6 55 ± 19.3 NS 65.5 ± 17.9 57.2 ± 22.7 NS NS SVi (ml/m2) 33.1 ± 12.7 30.4 ± 9.6 NS 34.1 ± 8.3 29.8 ± 11.1 NS NS LV mass (g) 185.7 ± 53.6 183.3 ± 48. NS 177.5 ± 48.4 169.5 ± 52.2 NS NS LVMi (g/m2) 103.6 ± 30 102.1 ± 25.9 NS 93.8 ± 29.9 89.4 ± 24.2 NS NS Biplane EF (%) 58 ± 15 62 ± 13 0.013 60 ± 9 66 ± 6 &lt;0.05 NS AV: Aortic valve; EDV: end diastolic volume; EF: ejection fraction; ESV: end systolic volume; GCS: Global circumferential strain; GLS: Global longitudinal strain; GRS: Global radial strain; LV: left ventricle; LVMi: left ventricular mass index; mPG: mean pressure gradient; SV: stroke volume; SVi: stroke volume index; Vel: velocity Data are expressed as mean ± SD. Comparisons were performed using paired Student"s t tests(parametric) or Wilcoxon paired test (non-parametric). *Pre and post intervention. ┼Comparison of pre/post-intervention measurement difference between the two intervention groups done using unpaired t-test

Abstract 623 Figure.

Characterization of colorectal mucus using infrared spectroscopy: a potential target for bowel cancer screening and diagnosis

Biological materials presenting early signs of cancer would be beneficial for cancer screening/diagnosis. In this respect, the suitability of potentially exploiting mucus in colorectal cancer was tested using infrared spectroscopy in combination with statistical modeling. Twenty-six paraffinized colon tissue biopsy sections containing mucus regions from 20 individuals (10 normal and 16 cancerous) were measured using mid-infrared spectroscopic imaging. A digital de-paraffinization, followed by cluster analysis driven digital color-coded multi-staining segmented the infrared images into various histopathological features such as epithelium, connective tissue, stroma, and mucus regions within the tissue sections. Principal component analysis followed by supervised linear discriminant analysis was carried out on pure mucus and epithelial spectra from normal and cancerous regions of the tissue. For the mucus-based classification, a sensitivity of 96%, a specificity of 83%, and an area under the curve performance of 95% was obtained. For the epithelial tissue-based classification, a sensitivity of 72%, a specificity of 88%, and an area under the curve performance of 89% was obtained. The mucus spectral profiles further showed contributions indicative of glycans including that of sialic acid changes between these pathology groups. The study demonstrates that infrared spectroscopic analysis of mucus discriminates colorectal cancers with high sensitivity. This concept could be exploited to develop screening/diagnostic approaches complementary to histopathology.

618 Adaptive myocardial mechanics in aortic stenosis patients

Introduction

Left ventricular (LV) hypertrophy in aortic stenosis (AS) becomes maladaptive over time, leading first to a reduction in global longitudinal strain (GLS) and in a later stage a reduction in ejection fraction (EF). The myocardial state of impaired GLS but preserved EF is a key remodeling turning point in AS, yet little is known about the coping mechanics of the LV at or around this sensitive juncture.

Aim

1) To study the relationship between LV mass index (LVMi) increase and measures of LV function, including strain in AS; 2) To investigate whether augmentation of global myocardial radial and circumferential strain (GRS, GCS) compensates for the GLS reduction in AS patients with preserved EF.

Methods

One-hundred and eleven patients with varying degrees of AS, and 20 age- and gender-matched healthy volunteers were prospectively enrolled. transthoracic echocardiography with offline strain analysis was performed using TomTec software. Intra- and inter-observer variability of linear LV internal dimensions/thickness, EF and strain indices was tested on 20 randomly selected patients.

Results

Clinical and demographic characteristics of cases and controls are shown in Figure 1. GLS was impaired in AS patients compared to controls. In AS with preserved EF (&gt;50%), as LVMi increased, GLS progressively improved up to a point, beyond which any further increase in LVMi appeared counter-productive with impairment of GLS (Figure 1). EF preservation in these AS patients was mediated by a compensatory supernormal augmentation of GRS and a smaller augmentation of GCS (Figure 1). We observed a significant inverse correlation between GRS and GLS (r = 0.3, p = 0.002), and a similar trend between GCS and GLS (r = 0.275, p = 0.004). Intraclass correlation coefficient was high for all measurements (0.7-0.9).

Conclusion

In patients with AS and preserved EF, progressive myocardial hypertrophy improves GLS up to a point beyond which GLS drops and GRS increase to compensate. This plasticity of myocardial mechanics, in particular the supranormal augmentation of GRS is what enables the pathologically hypertrophied AS ventricle to delay the otherwise inexorable decline in its global systolic function.

Abstract 618 Figure 1

023 For how long should we monitor ED palpitation patients in the outpatient setting?

Background

The IPED study showed that use of a smartphone-based event recorder (AliveCor) in ED patients presenting with palpitation or pre-syncope, increased the number of patients in whom an ECG was captured during symptoms over five-fold to more than 55% at 90 days (Reed MJet al. Lancet eClinical Medicine 2019; 8: 37–46). The pocket sized AliveCor (now Kardia) mobile (AliveCor, San Francisco, USA) is a monitoring device that requires the patient to trigger the ECG recording. With minimal training, two fingers from each hand are placed on the monitor (which can be connected to the back of a smartphone) for 30 s to take an ECG recording.

This pre-planned analysis looked at the time to symptomatic rhythm detection in the intervention (AliveCorgroup)to determine the optimum AliveCor device monitoring period in the outpatient setting.

Method and results

Pre-planned sub study analysis of a randomised controlled multi-centre trial. Participants ≥16 years old presenting to 10 UK hospital EDs with palpitation or pre-syncope whose underlying ECG rhythm during these episodes remained undiagnosed after ED assessment were enrolled. Time to symptomatic rhythm detection was recorded and analysed.

Conclusions

243 participants were recruited over an 18-month period. A symptomatic rhythm was detected at 90 days in 69 (n=124; 55.6%; 95% CI 46.9–64.4%) participants in the intervention (AliveCor) group.

92.8% of patients who recorded a symptomatic rhythm during the 90 day period recorded this rhythm during the first 28 days (figure 1/table 1).

Abstract 023 Figure 1

Time to symptomatic rhythm detection in the intervention (AliveCor) group (n=69)

Abstract 023 Table 1

Cumulative symptomatic rhythm detection in the intervention (AliveCor) group (n=69)

Conclusion: ED palpitation patients discharged with a smartphone-based event recorder such as the AliveCor should be reviewed after 4 weeks to enable efficient device usage and timely treatment if required. Patients in whom a diagnosis has not been made can be re-reviewed at 90 days. (1541 characters/285 words)

P3134Variations in anterior mitral valve leaflet restriction that may lead to the erroneous diagnosis of rheumatic heart disease

Introduction

Anterior mitral valve leaflet (AMVL) restriction is a prominent morphological feature of rheumatic heart disease (RHD). The World Heart Federation (WHF) criteria for echocardiographic diagnosis of RHD rely on the use of colloquial terms such as “dog-leg” to define AMVL restriction rather than a strict, reproducible definition. We recognise AMVL restriction when the tip of the leaflet is seen to point away from the interventricular septum and towards the posterior left ventricular (LV) wall at peak diastole in the parasternal long axis (PSLAX) view. This definition however risks inclusion of a finding commonly identified in our high-risk screening program (Echo in Africa- EIA) which demonstrates gradual AMVL bowing (so-called “slow-bow”) from the proximal to mid-leaflet but with free motion ('fluttering') of the tip during diastole. This is in contrast to RHD-related restriction which typically involves the distal AMVL tip only. We propose that the former is a normal variant of the AMVL and is unrelated to the RHD process, provided no concomitant morphological features of RHD are identified.

Purpose

Determine the prevalence of “slow-bow” AMVL restriction between two cohorts of schoolchildren with a documented high-and low-RHD prevalence.

Methods

Retrospective analysis of EIA data obtained from children (aged 13–18) attending two separate South African schools. The high-RHD prevalence school (HR) demonstrated a 0.8% rate of WHF “definite RHD”. The low-RHD prevalence school (LR) demonstrated no cases of WHF “definite RHD”. Cases of AMVL restriction were identified and classified according to the definitions provided above.

Results

A total of 941 screening studies (HR cohort n=577 /LR cohort n=364) were evaluated. 74 cases of AMVL restriction (12.82%, 95%, CI 10.34–15.80) were identified in the HR cohort of which 8 cases demonstrated AMVL-tip restriction (1.39%, 95%, CI 0.70–2.71) and 65 cases demonstrated “slow bow” (11.27%, 95%, CI 8.94–14.11). There were no cases of AMVL-tip restriction observed in the LR-cohort and 35 cases of “slow-bow”(9.62%, 95%, CI 7–13.08).

A. “Slow bow”; B. “Distal tip restriction”.

Conclusion

Our results support the hypothesis that “slow-bow” AMVL restriction is a common variant of the AMVL amongst South African school children and unrelated to the RHD process. Further research is required to investigate the exact mechanism underlying this form of AMVL restriction.

Acknowledgement/Funding

Edwards Lifescience EHM grant

Effects of Chronic Hypervitaminosis a on Global Plasma Metabolome Changes and Liver Gene Expression (OR05-06-19)

Objectives

Concerns about inadvertent chronic excessive vitamin A (VA) intakes due to overly frequent supplementation, fortification and voluntarily fortified products have been raised. Although chronic excessive VA intake can create liver abnormalities, clinically detectable signs of VA toxicity are rare, indicating the need for early biomarkers of tissue damage induced by excessive VA intake.

Methods

To identify early markers of VA toxicity, we induced chronic hypervitaminosis A in pigs (64 pigs, 8 per group) dosed with an oral supplement of retinyl propionate (0 up to 10,000 µg/KgBW) for 17 weeks. To assess the regulatory role of vitamin A in liver metabolism, a microarray analysis was performed to identify genetic regulation in liver tissue. Gene expression data were confirmed using qRT-PCR, and differentially expressed transcripts and pathways were identified using Genespring and Ingenuity Pathway Analysis (IPA). Additionally, two untargeted UPLC-MS assays (HILIC and C18 reversed phase) were applied to analyse plasma metabolites followed by univariate and multivariate analysis.

Results

Metabolomics analysis indicated that between 228 to 949 plasma metabolites were statistically significant between VA treated and control animals. The majority of metabolic changes observed in plasma were lipids, with ceramides, glycerophospholipids, lysoglycerophospholipids, sterol lipids and triacylglycerides enriched in both low and high VA dosed animals. Gene expression analysis confirmed significant changes in lipid metabolism, with pathways in metabolism of terpenoids and membrane lipids significantly increased by 2.4 fold.

Conclusions

The combined analysis of gene expression with untargeted metabolomics data confirm that changes in liver function and lipid metabolism offers an opportunity to develop a biomarker panel to diagnose pre-symptomatic hypervitaminosis A in humans.

Funding Sources

Supported by the Bill and Melinda Gates foundation.

The Effect of Chronic High Dose Vitamin a Supplementation on Lipid Metabolism in Adipose Tissue (P02-013-19)

Objectives

The objective of this study was to assess the impact of high-dose vitamin A (VA) on lipid metabolism. Previously, VA has been shown to enhance fat mobilisation, leading to a reduction in body fat. We hypothesise that hypervitaminosis A will increase expression of genes associated with lipid catabolism.

Methods

To induce chronic hypervitaminosis A, two groups of pigs (n = 8) were fed a commercial diet. The treatment group was additionally dosed, daily, with an oral supplement of retinyl propionate of 10,000 µg/KgBW for 17 weeks. To assess the impact of VA on lipid metabolism, a microarray analysis was performed to identify gene expression in adipose tissue. Differentially expressed transcripts and pathways were identified using Genespring and mapped to human orthologues for Ingenuity Pathway Analysis (IPA); gene fold changes were confirmed using qRT-PCR. Additionally, an untargeted UPLC-MS lipidomic analysis was carried out in serum samples to identify changes in lipd classes and their metabolites.

Results

In dosed animals, significant increases in plasma retinol (0.66 μmol/L) and liver retinyl ester concentrations (11.98 μmol/g both P < 0.001), as well as an increase in serum NEFA of 92.84 μmol/L (P = 0.001) were observed. Gene expression fold changes in subcutaneous adipose tissue were related to mitochondrial dysfunction and lipid metabolism, including increased expression of MT-CYTB (↑4.78x, P < 0.05) and ATP5A1 (↑3.13x, P < 0.05). Metabolomics confirmed changes in lipids and their metabolites relevant to adipose tissue in blood (P = 0.05), namely a decrease in triacylglyceride concentration and increases in acyl carnitine and cardiolipin concentrations.

Conclusions

An integrated pathway is suggested to explain the role of vitamin A in leading to increased lipolysis, β-oxidation and oxidative phosphorylation, but when in excess, markers of mitochondrial dysfunction were observed.

Funding Sources

Funded by the Bill and Melinda Gates foundation.

Multi-centre Randomised Controlled Trial of a Smartphone-based Event Recorder Alongside Standard Care Versus Standard Care for Patients Presenting to the Emergency Department with Palpitations and Pre-syncope: The IPED (Investigation of Palpitations in the ED) study

BACKGROUND

Patients with palpitations and pre-syncope commonly present to Emergency Departments (EDs) but underlying rhythm diagnosis is often not possible during the initial presentation. This trial compares the symptomatic rhythm detection rate of a smartphone-based event recorder (AliveCor) alongside standard care versus standard care alone, for participants presenting to the ED with palpitations and pre-syncope with no obvious cause evident at initial consultation.

METHODS

Multi-centre open label, randomised controlled trial. Participants ≥ 16 years old presenting to 10 UK hospital EDs were included. Participants were randomised to either (a) intervention group; standard care plus the use of a smartphone-based event recorder or (b) control group; standard care alone. Primary endpoint was symptomatic rhythm detection rate at 90 days. Trial registration number NCT02783898 (ClinicalTrials.gov).

FINDINGS

Two hundred forty-three participants were recruited over an 18-month period. A symptomatic rhythm was detected at 90 days in 69 (n = 124; 55.6%; 95% CI 46.9-64.4%) participants in the intervention group versus 11 (n = 116; 9.5%; 95% CI 4.2-14.8) in the control group (RR 5.9, 95% CI 3.3-10.5; p < 0.0001). Mean time to symptomatic rhythm detection in the intervention group was 9.5 days (SD 16.1, range 0-83) versus 42.9 days (SD 16.0, range 12-66; p < 0.0001) in the control group. The commonest symptomatic rhythms detected were sinus rhythm, sinus tachycardia and ectopic beats. A symptomatic cardiac arrhythmia was detected at 90 days in 11 (n = 124; 8.9%; 95% CI 3.9-13.9%) participants in the intervention group versus 1 (n = 116; 0.9%; 95% CI 0.0-2.5%) in the control group (RR 10.3, 95% CI 1.3-78.5; p = 0.006).

INTERPRETATION

Use of a smartphone-based event recorder increased the number of patients in whom an ECG was captured during symptoms over five-fold to more than 55% at 90 days. This safe, non-invasive and easy to use device should be considered part of on-going care to all patients presenting acutely with unexplained palpitations or pre-syncope.

FUNDING

This study was funded by research awards from Chest, Heart and Stroke Scotland (CHSS) and British Heart Foundation (BHF) which included funding for purchasing the devices. MR was supported by an NHS Research Scotland Career Researcher Clinician award.

Raman spectroscopy and multivariate analysis for the non invasive diagnosis of clinically inconclusive vulval lichen sclerosus

Vulval lichen sclerosus (LS) is a common inflammatory condition associated with an increased risk of developing vulval carcinoma. Diagnosis is usually clinical although biopsy is necessary if the diagnosis is uncertain or if there is a failure to respond to adequate initial treatment. Raman spectroscopy has the potential to be applied in vivo for near real time objective non-invasive optical diagnosis, avoiding the need for invasive tissue biopsies. The aim of this study was to evaluate the diagnostic performance of Raman spectroscopy for differentiating LS from other vulval conditions in fresh vulval biopsies. Biopsies were analysed from 27 women with suspected LS in whom the attending gynaecologist could not establish the diagnosis on clinical presentation alone. Spectral variance was explored using principal component analysis and in conjunction with the histological diagnoses was used to develop and test a multivariate linear discriminant classification model. This model was validated with leave one sample out cross validation and the diagnostic performance of the technique assessed in comparison with the pathology gold standard. After cross validation the technique was able to correctly differentiate LS from other inflammatory vulval conditions with a sensitivity of 91% and specificity of 80%. This study demonstrates Raman spectroscopy has potential as a technique for in vivo non-invasive diagnosis of vulval skin conditions. Applied in the clinical setting this technique may reduce the need for invasive tissue biopsy. Further in vivo study is needed to assess the ability of Raman spectroscopy to diagnose other vulval conditions before clinical application.

Procedural sedation of elderly patients by emergency physicians: a safety analysis of 740 patients

BACKGROUND

The elderly are perceived as a high-risk group for procedural sedation. Concern exists regarding the safety of sedation of this patient group by emergency physicians, particularly when using propofol.

METHODS

We analysed prospectively collected data on patients aged 75 yr or older undergoing sedation between October 2006 and March 2017 in the emergency department of a single centre. We used the World Society of Intravenous Anaesthesia International Sedation Task Force adverse event tool, stratifying identified adverse events according to consensus agreement.

RESULTS

Of 740 consecutive patients (median age 84 yr), 571 patients received propofol, 142 morphine and midazolam, and 27 other agents. We identified 19 sentinel events: 2 cases of hypoxia, 10 of apnoea (without hypoxaemia), 5 of hypotension, and 2 of both hypoxaemia and hypotension. We also identified 30 moderate, 41 minor, and 7 minimal risk adverse events. There were no adverse outcomes.

CONCLUSIONS

We observed safe sedation practice in this high-risk group of patients in this department. A sentinel adverse event rate of 2.6% including a hypoxaemia rate of 0.5%, with no adverse outcomes sets a benchmark for elderly sedation. We recommend quality pre-oxygenation, an initial propofol bolus of no more than 0.5 mg kg^-1, and a robust training and governance framework.

Prominent inter-scallop separations of the posterior leaflet of the mitral valve: an important cause of 'pathological' mitral regurgitation

The 2012 World Heart Federation (WHF) criteria for echocardiographic diagnosis of rheumatic heart disease (RHD) identify that the finding of 'pathological' mitral regurgitation (MR) in a screened individual increases the likelihood of detecting underlying RHD. Cases of isolated "pathological MR are thus identified as 'borderline RHD'. A large-scale echocardiographic screening program (Echo in Africa) in South Africa has identified that inter-scallop separations of the posterior mitral valve leaflet (PMVL) can give rise to 'pathological' MR. The authors propose that this finding when associated with isolated 'pathological' MR is unrelated to the rheumatic disease process. In this case report, we present two examples of 'pathological' MR related to inter-scallop separation from the Echo in Africa image database. We provide additional screening tips to accurately identify this entity.

P544The importance of contractile reserve when assessing asymptomatic patients with aortic stenosis

Asymptomatic patients may exhibit symptoms during objective exercise testing, but whether symptoms are due to the obstructively of the valve (typified by the mean gradient) or underlying ventricular function remains unknown. While the mean gradient is an easy parameter to measure no consensus about the measurement of contractile reserve exists. Longitudinal abnormalities may occur in the presence of a normal ejection fraction and the augmentation of these parameters is poorly described. To obtain an objective regarding patients exercise ability is best determined using cardiopulmonary exercise testing. We therefore examined echocardiographic predictors of exercise ability during cardiopulmonary exercise testing.24 asymptomatic patients with moderate to severe or severe aortic stenosis and preserved ejection fraction underwent stress echocardiography with simultaneous cardiopulmonary exercise testing. The primary assessment of exercise ability was the VO2peak and OUES. Echocardiography was measured at rest and during maximal exercise (defined as RER > 1)OUES and VO2peak showed a poor relationship with conventional parameters of severity including peak and mean gradients, AVA and dimensionless index, resting systolic function (by EF and TDI). During exercise systolic augmentation had a good relationship with exercise ability but the exercise mean gradient and exercise LVEF did not.Longitudinal systolic function and particularly systolic augmentation is the strongest predictor of exercise ability when compared to conventional measures of severity.VO2peakOUESS' exerciseRho=0.69 (p=0.001)R= 0.71 (p=0.001)S' restRho=0.52 (p=0.01)R= 0.44 (p=ns)Rest AV max VRho= 0.09 (p=ns)R= -0.08 (p=ns)Rest AV mean PGRho= 0.34 (p=ns)R=-0.10 (p=ns)Exercise AV max VRho=0.43 (p=0.05)R=0.23 (p=ns)Exercise AVmean PGRho= 0.51 (p=0.001)R=0.26 (p=ns)Rest AVARho=0.40 (p=ns)Rho=0.46 (p=0.04)Dimensionless indexRho=0.15 (p=ns)R=0.13 (p=ns)LVEF restRho=-0.18 (p=ns)R=-0.32 (p=ns)LVEF exerciseRho=0.18 (p=ns)R=0.17 (p=ns)S' - systolic velocity; V - velocity; AV - aortic valve; AVA- aortic valve area; LVEF - left ventricular ejection fraction.

Automated cytological detection of Barrett's neoplasia with infrared spectroscopy

BACKGROUND

Development of a nonendoscopic test for Barrett's esophagus would revolutionize population screening and surveillance for patients with Barrett's esophagus. Swallowed cell collection devices have recently been developed to obtain cytology brushings from the esophagus: automated detection of neoplasia in such samples would enable large-scale screening and surveillance.

METHODS

Fourier transform infrared (FTIR) spectroscopy was used to develop an automated tool for detection of Barrett's esophagus and Barrett's neoplasia in esophageal cell samples. Cytology brushings were collected at endoscopy, cytospun onto slides and FTIR images were measured. An automated cell recognition program was developed to identify individual cells on the slide.

RESULTS

Cytology review and contemporaneous histology was used to inform a training dataset containing 141 cells from 17 patients. A classification model was constructed by principal component analysis fed linear discriminant analysis, then tested by leave-one-sample-out cross validation. With application of this training model to whole slide samples, a threshold voting system was used to classify samples according to their constituent cells. Across the entire dataset of 115 FTIR maps from 66 patients, whole samples were classified with sensitivity and specificity respectively as follows: normal squamous cells 79.0% and 81.1%, nondysplastic Barrett's esophagus cells 31.3% and 100%, and neoplastic Barrett's esophagus cells 83.3% and 62.7%.

CONCLUSIONS

Analysis of esophageal cell samples can be performed with FTIR spectroscopy with reasonable sensitivity for Barrett's neoplasia, but with poor specificity with the current technique.

Screening for rheumatic heart disease: is a paradigm shift required?

This focused review presents a critical appraisal of the World Heart Federation criteria for the echocardiographic diagnosis of rheumatic heart disease (RHD) and its performance in African RHD screening programmes. It identifies various logistical and methodological problems that negatively influence the current guideline’s performance. The authors explore novel RHD screening methodology that could address some of these shortcomings and if proven to be of merit, would require a paradigm shift in the approach to the echocardiographic diagnosis of subclinical RHD.

Capnography for procedural sedation in the ED: a systematic review

INTRODUCTION

Procedural sedation and analgesia (PSA) is commonplace in the ED. Previous studies have identified capnography as a reliable indicator of PSA-induced respiratory depression. This review investigates the potential effect on patient safety of the use of capnography in addition to standard monitoring for adult patients undergoing PSA in the ED.

METHODS

MEDLINE, Embase, Scopus, CINAHL and Google Scholar were searched systematically for ED studies using capnography during PSA. Data extraction was performed by two independent authors. Using MedCalc V.13.3.3 and Meta-DiSc V.1.4, data were aggregated under the random-effects model and heterogeneity was assessed using Cochran's Q-test and the I² statistic.

RESULTS

Of the 737 studies that were screened, 7 studies met the eligibility criteria, representing a total of 662 patients. The aggregate diagnostic accuracy for capnography identifying an adverse event included a diagnostic OR of approximately 6 (OR: 5.87; 95% CI 2.41 to 14.3; p<0.001), sensitivity 0.82 (95% CI 0.76 to 0.87), specificity 0.6 (95% CI 0.55 to 0.64), negative likelihood ratio 0.3 (95% CI 0.12 to 0.75) and positive likelihood ratio 1.89 (95% CI 1.53 to 2.34). There was a lack of statistical evidence for a difference in the proportion of adverse events detected when capnography was used in addition to standard monitoring (48.8% (95% CI 32.85 to 64.92)) compared with chance alone (50%).

CONCLUSIONS

There is no firm evidence that capnography provides additional safety compared with standard monitoring alone during PSA in adults in the ED. There is a paucity of published research involving preoxygenated patients who remain on high-flow oxygen throughout PSA. Well-powered randomised controlled trials, employing an accepted adverse event reporting tool in such patients, are required. Until then, we advocate continued compliance with current professional recommendations for the use of capnography during PSA in adults in the ED.

Paediatric procedural sedation using ketamine in a UK emergency department: a 7 year review of practice

BACKGROUND

Ketamine is growing in popularity for procedural sedation in the paediatric population, yet safety concerns remain. We performed a retrospective review of practice and outcomes of paediatric ketamine sedation using the World SIVA International Sedation Task Force reporting tool.

METHODS

A retrospective inspection of the dedicated emergency department electronic sedation database and subsequent note and sedation chart review was performed for all paediatric sedations throughout a 7 yr period from September 2006. All adverse events were stratified.

RESULTS

During the study period, procedural sedation was provided for a total of 243 children, of whom 215 were sedated with ketamine, most commonly for wound management (n=131). The median patient age was 4 yr (14 months to 15 yr), and 63.7% were male. Of the total, 76.7% were discharged home either directly (n=101) or after brief observation (n=64). One patient required subsequent general anaesthesia after a failed sedation with paradoxical agitation. Of the total, 9.8% of patients had an adverse event, the most severe risk stratification being 'minor risk'. All interventions were 'minimal risk'. There were no 'sentinel risk' outcomes.

CONCLUSIONS

These data support the ongoing use of ketamine for paediatric procedural sedation in the emergency department by emergency physicians. Relatively high resource requirements mean that ensuring adequate numbers of procedures may prove challenging.

Infrared micro-spectroscopy for cyto-pathological classification of esophageal cells

We report results from a study utilizing infrared spectral cytopathology (SCP) to detect abnormalities in exfoliated esophageal cells. SCP has been developed over the past decade as an ancillary tool to classical cytopathology. In SCP, the biochemical composition of individual cells is probed by collecting infrared absorption spectra from each individual, unstained cell, and correlating the observed spectral patterns, and the variations therein, against classical diagnostic methods to obtain an objective, machine-based classification of cells. In the past, SCP has been applied to the analysis and classification of cells exfoliated from the cervix and the oral cavity. In these studies, it was established that SCP can distinguish normal and abnormal cell types. Furthermore, SCP can differentiate between truly normal cells, and cells with normal morphology from the vicinity of abnormalities. Thus, SCP may be a valuable tool for the screening of early stages of dysplasia and pre-cancer.

Enhanced recovery programmes in colorectal surgery are less enhanced later in the week: An observational study

Objectives

Since the introduction and favourable early results of the enhanced recovery programme more than a decade ago, it has become increasingly popular following major abdominal surgery. The programme has now been adopted in the UK. The aim of our study was to see if the day of surgery affected hospital stay and we compared patients who had colorectal surgery early in the week (Monday to Wednesday) with those who had it later in the week (Thursday to Friday).

Design

Patient outcomes were studied between May 2010 and April 2011 from a prospectively maintained database. All colorectal surgeons involved in the enhanced recovery programme in our unit have a flexible rota and so no surgeon was operating on a particular day to avoid bias. An enhanced recovery programme protocol was utilised for all the patients with no bowel preparation, early feeding and early mobilisation.

Setting

Study was carried out at the University Hospitals of Leicester.

Participants

Patients undergoing elective colorectal resection between Monday and Friday.

Main outcome measure

Hospital stay.

Results

Two hundred and twenty-seven patients underwent surgery and were on the enhanced recovery programme during this period. Two (0.9%) patients who had surgery on a Sunday were excluded. Two hundred and twenty-five patients were analysed of which 155 (69%) were in the group (Monday to Wednesday) and 70 (31%) in the group (Thursday to Friday). No significant differences were observed amongst the groups for age (p = 0.129), sex (p = 0.555), tumour location (p = 0.140), operation performed (p = 0.127), type of surgery (laparoscopy or open, p = 0.892), complications (p = 0.428). However, a significant shorter length of stay was present in the first group six days (interquartile range: 4–10) versus eight days (interquartile range: 5–11) (p = 0.045).

Conclusion

Operating on colorectal patients early in the week is associated with a significant decreased hospital stay. This should be put into consideration by units practising enhanced recovery programme if the maximal benefit of this is to be attained.