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Emergency percutaneous coronary intervention of the left main (LM ePCI) coronary artery necessitated by acute coronary syndrome is associated with a high risk of mortality. However, optimal treatment strategies and related outcomes remain undefined in this group. We undertook a multi-center, retrospective, observational cohort study of consecutive patients requiring LM ePCI between 2011 and 2018 and reported the coronary anatomy, treatment strategies, outcomes, and predictors of mortality. A total of 116 consecutive cases were included. Patients were predominantly male (85%) with a median age of 68.0 years; 12 patients (10%) had previous coronary artery bypass grafting. ST-elevation was noted in 76 (66%); 30 (26%) presented with an out-of-hospital cardiac arrest (OOHCA) and 47 (41%) with cardiogenic shock. The most frequent pattern of disease was Medina 1,1,1, seen in 59 patients (51%). The commonest revascularization strategy was provisional stenting (95 cases, 82%) with improved or thrombolysis in myocardial infarction 3 flow seen in 85 cases (73%). All-cause mortality was 35% at 30 days, rising to 58% at 5 years. Adverse predictors of 30-day mortality included presentation with cardiogenic shock (p = 0.018) and OOHCA (p = 0.020), whereas improved flow and/or thrombolysis in myocardial infarction 3 flow in both circumflex and left anterior descending artery afforded a better prognosis (p = 0.028). In conclusion, patients who underwent LM ePCI are a high-risk subgroup and commonly present with cardiogenic shock and OOHCA. Provisional stenting appears to be the preferred option with the successful restoration of coronary flow in most cases despite complex anatomy. High 30-day mortality is driven by the presence of cardiogenic shock, OOHCA, and failure to restore or improve coronary flow.

Introduction Cardiovascular events in patients with inherited bleeding disorders are challenging to manage. The risk of bleeding secondary to antithrombotic treatment must be balanced against the risk of thrombosis secondary to haemostatic therapy. Methods Patients with inherited bleeding disorders with coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI) or atrial fibrillation (AF) from a single centre (2010-2018) are included. Results A total of 11 patients undergoing CABG (n = 3), PCI (n = 5) or with AF (n = 3) and a diagnosis of haemophilia A (n = 8), haemophilia B (n = 1), factor XI deficiency (n = 1) and von Willebrand disease (n = 1) managed by a multidisciplinary team are reported. In patients undergoing CABG, factor levels were normalized for 7-10 days with trough levels of 70-80% with severe patients continuing high-dose factor prophylaxis (trough 20-30%) three weeks post-operatively with daily aspirin. In a patient with mild haemophilia A and an inhibitor, recombinant factor VIIa dosing was monitored with thromboelastometry. For PCI, a 3rd-generation drug-eluting stent with one month of dual antiplatelet therapy in addition to high-dose prophylaxis as needed was preferred. Patients with AF and severe haemophilia did not receive antithrombotic treatment, and a thrombin generation assay was used to guide heparin dosing in mild haemophilia. Conclusion Our experience demonstrates the importance of interdisciplinary communication to identify strategies that decrease the risk of bleeding and thrombosis. The use of extended, increased intensity prophylaxis facilitated antiplatelet therapy. Global assays may help balance the intensity of haemostatic and antithrombotic treatment.

ObjectivesTo understand the impact of COVID-19 on delivery and outcomes of primary percutaneous coronary intervention (PPCI). Furthermore, to compare clinical presentation and outcomes of patients with ST-segment elevation myocardial infarction (STEMI) with active COVID-19 against those without COVID-19.MethodsWe systematically analysed 348 STEMI cases presenting to the PPCI programme in London during the peak of the pandemic (1 March to 30 April 2020) and compared with 440 cases from the same period in 2019. Outcomes of interest included ambulance response times, timeliness of revascularisation, angiographic and procedural characteristics, and in-hospital clinical outcomesResultsThere was a 21% reduction in STEMI admissions and longer ambulance response times (87 (62–118) min in 2020 vs 75 (57–95) min in 2019, pConclusionThese findings suggest that PPCI pathways can be maintained during unprecedented healthcare emergencies but confirms the high mortality of STEMI in the context of concomitant COVID-19 infection characterised by a heightened state of thrombogenicity.

The outbreak of COVID-19 in Wuhan, China and its declaration as a global pandemic by WHO has left the medical community under significant pressure to rapidly identify effective therapeutic and preventative strategies. Chloroquine (CQ) and its analogue hydroxychloroquine (HCQ) were found to be efficacious against SARS-CoV-2 when investigated in preliminary in vitro experiments. Reports of success in early clinical studies were widely publicised by news outlets, politicians and on social media. These results led several countries to approve the use of these drugs for the treatment of patients with COVID-19. Despite having reasonable safety profiles in the treatment of malaria and certain autoimmune conditions, both drugs are known to have potential cardiotoxic side effects. There is a high incidence of myocardial injury and arrhythmia reported with COVID-19 infection, and as such this population may be more susceptible to this side-effect profile. Studies to date have now demonstrated that in patients with COVID-19, these drugs are associated with significant QTc prolongation, as well as reports of ventricular arrhythmias. Furthermore, subsequent studies have failed to demonstrate clinical benefit from either drug. Indeed, clinical trials have also been stopped early due to safety concerns over HCQ. There is an urgent need for credible solutions to the global pandemic, but we argue that in the absence of high-quality evidence, there needs to be greater caution over the routine use or authorisation of drugs for which efficacy and safety is unproven.

Introduction Human immunodeficiency virus (HIV)/ acquired immune deficiency syndrome (AIDS) was traditionally associated with severe heart failure, pulmonary hypertension and myocarditis but this is rarely seen following the advent of antiretroviral therapy (ART). Previous studies in asymptomatic people living with HIV (PLWH) have revealed a high burden of cardiovascular disease (CVD), and subclinical myocardial inflammation as detected by cardiac magnetic resonance imaging (CMR). The H-ART to Heart study was designed to assess the prevalence of CVD in PLWH. In this sub-study, we aim to assess bio-markers, structural and functional cardiac changes associated with HIV using CMR. Methods In this cross-sectional study, we recruited asymptomatic Caucasian men who have sex with men (MSM) diagnosed with HIV > 10yrs ago, aged 35-55 years, with undetectable viral loads on ART. They were compared to HIV-negative age and ethnicity MSM matched controls. Those with Q-Risk3 CVD risk factors (hypertension, hyperlipidaemia, diabetes, smoking, inflammatory arthritis, depression, severe mental illness) or hepatitis co-infection were excluded. Assessments included blood pressure (BP); bloods for inflammation; transthoracic echocardiography for all participants and stress perfusion CMR with multiparametric mapping for PLWH. We compared CMR results with a previously selected control group of healthy volunteers with no cardiovascular risk factors. Results 45 participants were recruited (26 MLWH; 19 HIV- MSM), mean results for MLWH were as follows: duration of HIV 17.8±6.4yrs, duration on ART 10.7±5.2yrs, nadir CD4 count 318±145 cells/μL, current CD4 count 610±150 cells/μL and current viral load CMR data for LVEF was comparable to that reported by echocardiography, most parameters were similar between the groups aside from statistically significant higher T2 (46.2±1.6 v 44.4±2.5ms; P Conclusion From our small study of well treated asymptomatic MLWH with low CVD risk profiles, we were able to detect subtle differences in inflammatory biomarkers compared to controls, However this did not translate to evidence of detectable myocardial pathology classically associated with HIV (cardiomyopathy, myocarditis). There was no difference in LVEF%, LV Mass-I or native T1, a marker of diffuse fibrosis, which is different to previous published data, perhaps due to our strict inclusion criteria. However T2, a more specific marker of myocardial oedema, and more non-specific LGE were detected in MLWH. This may indicate an early signal of myocardial inflammation in well treated MLWH. Conflict of Interest None

Introduction 37.9 million people worldwide are living with HIV (human immunodeficiency virus), acquired immune deficiency syndrome (AIDS)-related deaths have reduced by 51% since the peak in 2004. 42% of those infected are BWLWH yet represent only 9% of those included in clinical trials. HIV/AIDS has been shown to be associated with the development of heart failure, pulmonary hypertension and myocarditis. Previous studies in asymptomatic PLWH have revealed a high burden of underlying CVD and subclinical myocardial inflammation as detected by CMR. The H-ART to Heart study is designed to examine the burden of cardiovascular disease (CVD) in asymptomatic PLWH compared to HIV negative controls (-) excluding traditional CV risk factors. Methods A cross-sectional study comparing asymptomatic BWLWH aged 35-55yrs (diagnosed >10 yrs, with undetectable viral loads) to HIV negative controls. Black African/Caribbean women without known CV risk factors (hypertension, hyperlipidaemia, diabetes, smoking, inflammatory arthritis, depression, severe mental illness) or hepatitis co-infection were included. Assessment included blood pressure (BP), bloods including NT-ProBNP. Echocardiography was performed in all participants and stress perfusion CMR with multiparametric mapping for BWLWH. We compared CMR results with a previously selected control group. Results 48 participants have been recruited (23 BWLWH,25 controls; mean age 47.7±4.1 v 44.7±6.2yrs, P=0.06; mean BP 125/77 v 123/79mmHg), mean results for BWLWH were as follows: duration of HIV 17.6±6.2 yrs, duration of ART 11.5±5.2 yrs, nadir CD4 count 262±158 cells/μL, current CD4 count 662±188 cells/μL and current viral load A MRI sub-study data showed no difference in LV mass, LVEDV, T1, T2 with no evidence of ischaemia or myocarditis between the groups, although number are small (Table 2). Conclusion Preliminary data from our study of asymptomatic low risk BWLWH without traditional CVD risk factors removed indicates raised PAP which cannot be explained by hypertension, diastolic dysfunction, ischaemia or previous myocarditis. The cause of the raised PAP is unclear and requires further investigation. Whether this finding is of importance in CV risk assessment of BWLWH remains to be seen. Conflict of Interest None

Fibre optic sensors are well suited to measuring fluid flow in many contexts, and recently there has been burgeoning interest in their application to direct, invasive measurement of blood flow within human vasculature. Depending on the sensing method used and assumptions made, these intravascular measurements of blood flow can provide information about local blood velocity, volumetric flow, and flow-derived parameters. Fibre optic sensors can be readily integrated into medical devices, which are positioned into arteries and veins to obtain measurements that are inaccessible or cumbersome using non-invasive imaging modalities. Measurements of flow within coronary arteries is a particularly promising application of fibre optic sensing; recent studies have demonstrated the clinical utility of certain flow-based parameters, such as the coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR). In this review, research and development of fibre optic flow sensors relevant to intravascular flow measurements are reviewed, with a particular focus on biomedical clinical translation.

All-optical ultrasound transducers are well-suited for use in imaging during minimally invasive surgical procedures. This requires highly miniaturised and flexible devices. Here we present optical ultrasound transmitters for imaging applications based on modified optical fibre distal tips which allow for larger transmitter element sizes, whilst maintaining small diameter proximal optical fibre. Three optical ultrasound transmitter configurations were compared; a 400 µm core optical fibre, a 200 µm core optical fibre with a 400 µm core optical fibre distal tip, and a 200 µm core optical fibre with a 400 µm core capillary distal tip. All the transmitters used a polydimethylsiloxane-dye composite material for ultrasound generation. The material comprised a photostable infra-red absorbing dye to provide optical absorption for the ultrasound transduction. The generated ultrasound beam profile for the three transmitters was compared, demonstrating similar results, with lateral beam widths ca. 30 MHz. These highly flexible ultrasound transmitters can be readily incorporated into medical devices with small lateral dimensions.

We thank Golomb et al. ([1][1]) for their timely publication on race and percutaneous coronary intervention outcomes. As the studies included were international, it is important to distinguish what percentage were black Americans versus Africans, as they have diverging risk profiles ([2][2]).

Introduction Antiretroviral therapy (ART) has dramatically reduced morbidity and mortality among people living with HIV (PLWH), including wasting syndrome. Metabolic and cardiovascular diseases are leading causes of death for PLWH in high-income countries. Obesity is increasing in the HIV population but a lack of data exists in PLWH, and the association with cardiovascular risk. The aim to determine if central obesity (measured using waist to hip ratio) is a better predictor of CV risk than Body Mass Index (BMI) which is the current standard to define obesity in PLWH. Methods Single centre, prospective study performed in a large metropolitan HIV unit. 129 PLWH had weight, height, waist and hip circumference, and blood pressure (BP) recorded. Data on sex, age, ethnicity, past medical history including CV risk factors and kidney disease, smoking status and postcode was used to calculate waist to hip ratio (W/H), BMI and Q-Risk2. Results The study population included 30 (23%) women and 98 (77%) men; 76 (59%) Caucasian, 38 (30%) black African/Caribbean and 14 (11%) were other ethnicity. In total, 43 (34%) were overweight and 31 (24%) obese using BMI measurement, this changed to 25 (20%) and 39 (30%) when using WHR. Q-Risk2 demonstrated that 82 PLWH (64%) had mild risk, 25 (20%) moderate, and 21 (16%) were high cardiovascular risk (excluding HIV as a risk factor). There was significant correlation between WHR and Q-Risk2 (r=0.44, p20 (high risk). WHR performed significantly better than BMI (AUC 0.58, 95% CI 0.49–0.67, p=0.24) at predicting Q-Risk2 (p=0.02 for difference, graph C). W/H ratio and BMI against Q-Risk 2 Conclusion Temporal change in waist circumference can indicate change in abdominal fat, with increased abdominal fat being associated with increased CV risk. WHR is superior to BMI at predicting high risk (Q-Risk >20%). It should be included as part of routine clinical assessment and lifestyle intervention implemented to reduce CV risk in PLWH.

Background Antiretroviral therapy (ART) has dramatically improved the prognosis in PLWH with survival nearing that of HIV negative people. PLWH may develop significant comorbidities as they age including cardiovascular disease (CVD) such as myocardial infarction, sudden cardiac death, heart failure, as well as subclinical evidence of myocardial inflammation. Overall, ART treated patients are at an increased CVD risk with some studies quoting a 2.2 fold relative risk. Aim To assess the incidence of functional, structural and tissue characterisation changes in PLWH using CMR with multiparametric mapping Methods 39 PLWH (34 men, mean age 55.8±10.9, mean duration of HIV 17.8±9.29 years) and 29 healthy volunteers (20 men, mean age 45.1±8.3) underwent CMR with late gadolinium enhancement (LGE) imaging, T1 and T2 mapping. Results Of PLWH, only 7 scans (18%) were normal. LV ejection fraction was significantly lower and LV mass significantly higher compared to controls. Native T1, a marker of diffuse fibrosis or increased myocardial water content was no different between the groups. T2, a more specific marker of myocardial oedema, was elevated in PLWH. Sixteen PLWH (41%) had evidence of LGE including 8 with an ischaemic pattern (7 sub-endocardial and one transmural) and 8 with a non-ischaemic pattern (5 with mid-wall enhancement and 3 with RV insertion point LGE. No controls had evidence of LGE. Student t-Test: PLWH versus controls PLWH (n=39) Control (n=29) P-value LVEF (%) 59±15 67±5 Conclusion This study identifies a number of cardiac changes associated with HIV and prolonged treatment with ART. The elevated LV mass may be associated with hypertension, commonly found in PLWH. The elevated myocardial T2 compared to controls may be due to chronic inflammation associated to prolonged HIV exposure. There was no evidence of diffuse fibrosis but focal areas of non-ischaemic scar were a common finding which may relate to previous myocarditis or HIV-related cardiomyopathy. A fifth of PLWH also had evidence of previous myocardial infarction. We propose to image asymptomatic PLWH to further classify, diagnose and treat a vulnerable group of patients who are now described as having a normal life expectancy.

Background With advances in antiretroviral therapy, most deaths in people with HIV are now attributable to non-communicable illnesses. The global burden of cardiovascular disease (CVD) in people living with HIV (PLWH) has tripled over the past 2 decades. A large meta-analysis suggests PLWH are twice as likely to develop CVD than the general population, however this data included a large proportion of individuals from sub-Saharan Africa and who were treatment naive. Data from the Swiss HIV Cohort Study suggests that PLWH have a similar degree of non-calcified/mixed plaque and high-risk plaque; less calcified coronary plaque; lower coronary atherosclerosis (CA) involvement; and lower severity scores than HIV-negative persons with similar Framingham risk scores. The British HIV Association advocate the use of Q-Risk 3 risk stratification tool despite the fact that HIV was not found to be a significant risk factor in the development and validation of this tool. For our UK population of PLWH a paucity of data exists despite a belief that PLWH are at increased risk of coronary atherosclerosis and cardiac death. Aim To assess survival after CA diagnosis and compare it to the general population. Methods A retrospective analysis from a large metropolitan hospital, of PLWH with a confirmed diagnosis of CA on invasive coronary angiography. Information from the HIV database and coronary angiogram database were combined. Notes were checked using the electronic patient records and mortality data was obtained from the NHS spine. The Global Registry of Acute Coronary Event (GRACE) risk scores were calculated at the time of CA diagnosis and survival rates were calculated using Kaplan–Meier analysis. These results were superimposed onto those from the UK-Belgium GRACE registry. Results We identified 52 PLWH who were diagnosed with CA based on angiography. 48 (92%) were men, mean age at time of procedure 50.7 (SD ± 9.3) years. 26 PLWH had HIV viral load 24 (46%) patients had an elective coronary angiogram, 13 (25%) had NSTEMI, 15 (29%) STEMI. 17 (32%) patients had hypercholesterolaemia, 8 (15%) hypertension, 9 (17%) were diabetics on oral medication, 3 (6%) on insulin, 24 (46%) ex-smokers, 7 (13%) smokers, 16 (31%) had known positive family history. Only 3 (6%) patients had renal failure on dialysis, the rest had a creatinine GRACE scores were performed on those with ACS (Acute Coronary Syndrome), 25 were categorised as low risk ( 140). Mean GRACE Score 80.7 (±19.6). Mean duration of HIV was 20.1 (±6.9) years, mean duration of follow up from procedure 2, 138 days. 8 patients died during this period (figure 1.) Conclusion We present UK data on PLWH and demonstrate that, despite an initial low GRACE risk score, the long term survival rates over 5 years tracks that of an intermediate risk group. We propose that PLWH should be screened and treated aggressively for CA if identified. Our results may represent a sub-group of PLWH who have more aggressive CVD and over represented cardiovascular risk factors. These patients were diagnosed a long time ago with low CD4 nadirs, and may have had long periods of detectable viraemia. Further work on a current UK cohort is required. Conflict of Interest None

Introduction Antiretroviral therapy (ART) has dramatically reduced morbidity and mortality among people living with HIV (PLWH), including wasting syndrome. Metabolic and cardiovascular (CV) diseases are leading causes of death for PLWH in high-income countries. Obesity is increasing in the HIV population but a lack of data exists in PLWH, and the association with cardiovascular risk. The aim to determine if central obesity (measured using waist to hip ratio) is a better predictor of CV risk than Body Mass Index (BMI) which is the current standard to define obesity in PLWH. Methods Single centre, prospective study performed in a large metropolitan HIV unit. 129 PLWH had weight, height, waist and hip circumference, and blood pressure (BP) recorded. Data on sex, age, ethnicity, past medical history including CV risk factors and kidney disease, smoking status and postcode was used to calculate waist to hip ratio (W/H), BMI and Q-Risk2. Results The study population included 30(23%) women and 98(77%) men; 76(59%) Caucasian, 38(30%) black African/Caribbean and 14 (11%) another ethnicity. In total, 43(34%) were overweight and 31(24%) obese using BMI measurement, this changed to 25(20%) and 39(30%) when using WHR. Q-Risk2 demonstrated that 82 PLWH (64%) had mild risk, 25 (20%) moderate, and 21(16%) were high cardiovascular risk (excluding HIV as a risk factor). There was significant correlation between WHR and Q-Risk2 (r=0.44, p 20 (high risk). WHR performed significantly better than BMI (AUC 0.58, 95% CI 0.49–0.67, p=0.24) at predicting Q-Risk2 (p=0.02 for difference, graph C). Conclusion Temporal change in waist circumference can indicate change in abdominal fat, with increased abdominal fat being associated with increased CV risk. WHR is superior to BMI at predicting high risk (Q-Risk >20%). It should be included as part of routine clinical assessment and lifestyle intervention implemented to reduce CV risk in PLWH. Conflict of Interest None

With intravascular Optical Coherence Tomography (IVOCT), phantom models are invaluable for system characterization and clinical training. However, accurately simulating 3D tissue geometries and heterogeneous optical properties has been challenging with phantom fabrication methods used to date. Anatomical phantom models typically require mesoscale structures integrated with heterogenous materials to simulate optical scattering and absorption by vascular tissue. In this study, we showed that two photon polymerisation (2PP) 3D printing offers the potential to generate complex tissue phantom scaffolds with sub-micron resolution (

Background Cardiac involvement is the main driver of outcome in systemic amyloidosis, but the relationship between amyloid deposits and outcomes is not well understood. The simple explanation of physical, mechanical replacement of the interstitium by amyloid seems insufficient. Preliminary studies support the hypothesis that myocardial ischaemia could contribute to cell damage. Purpose (1) To assess myocardial ischaemia in cardiac amyloidosis. (2) To compare patients with cardiac amyloidosis to patients assessed on invasive coronary angiography (ICA) to have normal coronary physiology (NCP), microvascular dysfunction (MVD) and triple vessel coronary disease (3VD). (3) To assess correlation of perfusion mapping to markers of disease severity and prognosis. Methods 86 patients and 20 healthy volunteers (HV) underwent CMR at 1.5T (Siemens) with standard cine, PSIR-LGE, T1,T2,Extracellular Volume (ECV) mapping and adenosine stress with myocardial blood flow (MBF) mapping. Thirty-eight patients also underwent ICA with 3 vessel assessment of Index of Microcirculatory Resistance and Fractional Flow Reserve: 7 had cardiac amyloidosis, 8 had NCP, 15 had MVD and 8 had 3VD. Results Cardiac amyloidosis patients had severe reduction in stress MBF and myocardial perfusion reserve (MPR) (1.22 ml/g/min±0.70 and 1.62±0.63) compared to HV (3.21 ml/g/min±0.64,p Conclusion Myocardial ischaemia is common in cardiac amyloidosis – with stress MBF and MPR similar to that of patients with 3VD. The reduction correlates with the degree of amyloid infiltration and markers of adverse prognosis, highlighting the potential role of myocardial ischaemia as a key mechanism in the pathophysiology of cardiac amyloidosis.

Background Assessment of hyperaemia during adenosine stress CMR remains a clinical challenge with lack of a gold standard marker of adequate stress. Multiple parameters including the splenic switch off (SSO) sign, heart rate response (HRR) and blood pressure response (BPR) are used in clinical practice. Perfusion mapping provides a pixelwise representation of myocardial blood flow (MBF), allowing for measurement of MBF at a regional level. This may provide an alternative tool for assessment of hyperaemia. Objectives To validate the use of stress MBF for assessment of hyperaemic response and compare this to currently used clinical markers. Methods In total, 216 subjects were recruited. This included 3 cohorts: 1) Derivation cohort (22 healthy volunteers) to identify a stress MBF threshold value representative of the normal minimum response to adenosine; 2) Validation cohort (37 patients with suspected coronary disease) who underwent stress CMR and invasive coronary physiological assessment on the same day, to validate the stress MBF threshold value against invasive markers of hyperaemia; 3) Clinical cohort (159 patients undergoing clinically-indicated adenosine stress CMR) to assess the presence of stress MBF-defined hyperaemia and other physiological markers of hyperaemia (SSO, HHR and BPR). Results From the derivation cohort, maximum stress MBF (SMBFmax) >1.43 ml/g/min was derived as the threshold value of hyperaemia (defined as 1.96 standard deviations below the sample mean of lowest stress MBF values). This threshold was tested in the validation cohort: 100% of patients with invasive evidence of hyperaemia demonstrated SMBFmax >1.43 ml/g/min, 81% had SSO and 81% had HRR >10 bpm. Of the clinical cohort, 93% had hyperaemia defined by SMBFmax compared to 71% using SSO and 81% using HRR. SMBFmax was no different in those with or without SSO (2.58±0.89 ml/g/min vs 2.54±1.04 ml/g/min, p=0.84) but those with HRR had significantly higher SMBFmax (2.69 ml/g/min vs 1.95 ml/g/min, p HRR >16 bpm was able to predict SMBFmax >1.43 ml/g/min with sensitivity 63% and specificity 91% (AUC 0.87, p Conclusion Adenosine-induced increase in MBF measured using perfusion mapping is accurate for the confirmation of hyperaemia during stress CMR studies and is superior to traditional, clinically used markers of adequate stress.

Vascular phantoms are crucial tools for clinical training and for calibration and validation of medical imaging systems. With current methods, it can be challenging to replicate anatomically-realistic vasculature. Here, we present a novel method that enables the fabrication of complex vascular phantoms. Poly(vinyl alcohol) (PVA) in two forms was used to create wall-less vessels and the surrounding tissue mimicking material (TMM). For the latter, PVA cryogel (PVA-c) was used as the TMM, which was made from a solution of PVA (10% by weight), distilled water, and glass spheres for ultrasonic scattering (0.5% by weight). PVA-c is not water soluble, and after a freeze-thaw cycle it is mechanically robust. To form the wall-less vessels, vessel structures were 3D printed in water-soluble PVA and submerged in the aqueous solution of PVA-c. Once the PVA-c had solidified, the 3D printed PVA vessel structures were dissolved in water. Three phantoms were created, as initial demonstrations of the capabilities of this method: a straight vessel, a stenosed (narrowed), and a bifurcated (branched) vessel. Ultrasound images of the phantoms had realistic appearances. We conclude that this method is promising for creating wall-less, anatomically realistic, vascular phantoms.

Background: Coronavirus disease-2019 (COVID-19) poses a risk for health care workers necessitating modifications to existing medical pathways In particular, managing patients with suspected COVID-19 represents a risk to the delivery of a primary percutaneous coronary intervention (PPCI) pathway where time-dependent revascularization is key Methods: We sought to evaluate the effect of the COVID-19 pandemic on an established ambulance-triggered PPCI program involving 2 high-volume heart attack centers in London, United Kingdom A systematic analysis was performed in patients with ST-segment elevation myocardial infarction undergoing PPCI comparing the COVID-19 pandemic period March 1, 2020, to April 30, 2020, with a control group from the previous year Results: During the study period, admissions through the PPCI pathway decreased by 34% The time from symptoms onset to first call for help (2020: 11 min vs 2019: 12 min;p = 0 90) and from symptom onset to arrival at PPCI center (2020: 183 min vs 2019: 178 min;p = 0 99) were comparable;however, the time from arrival at PPCI center to revascularization decreased (2020: 44 min vs 2019: 53 min;p = 0 0004) In-hospital mortality during the study period was significantly lower (5% vs 15%;p = 0 04) COVID-19–positive patients (n = 8) had higher rates of cardiogenic shock (25%), intensive care unit admission (50%), and inpatient mortality (38%) [Formula presented] Conclusion: Our data show that the modifications to the existing PPCI pathway were not associated with treatment delay or adverse outcome The reduction in ST-segment elevation myocardial infarction presentations raises concern that patients may not be seeking appropriate medical attention for chest pain Importantly, we demonstrate that PPCI can be delivered safely and efficiently during the COVID-19 pandemic Categories: OTHER: COVID-19

In current-generation intracoronary (IC) imaging devices, ultrasound (US) is generated and received electrically, using piezoelectric transducers. With this technology it has been challenging to achieve both high resolution and high imaging depths, and also to provide molecular contrast. All-optical

Intravascular (IV) imaging in percutaneous coronary interventions can be invaluable to treat coronary artery disease, to facilitate decision making and to guide stent placement. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are both established IV imaging modalities. However, achieving contrast for specific structures such as lipid plaques can be challenging; with OCT, visualisation is typically limited to tissue depths less than 2 mm. Photoacoustic (PA) imaging provides contrast that is complementary to those of IVUS and OCT, and with previous demonstrations, visualisation of lipid plaques at depths greater than 4 mm has been achieved. In this study, we developed an intravascular PA probe that comprises a commercial OCT catheter and a high sensitivity miniature fibre optic ultrasound sensor with a Fabry-Perot cavity. This probe, which can provide both PA imaging and OCT, had a maximum width of 1.2 mm. The PA excitation sources included both pulsed and modulated lasers at different wavelengths. The omni-directionality of the US sensor allowed for three-dimensional PA images. The PA-OCT probe was characterised using a series of resolution phantoms, including fine carbon fibres. It was found that with PA imaging, the probe can provide a lateral resolution better than 25 µm and an axial resolution better than 100 µm at the optical focus. Co-registered PA and OCT images of blood vessels ex-vivo with stents and lipid injections were acquired. We conclude that PA imaging with OCT catheters is viable and that it has strong potential to guide clinical interventions.

Intravascular ultrasound (IVUS) imaging probes can be invaluable for guiding minimally invasive procedures such as coronary stent placement. With current IVUS catheters, ultrasound is generated and received electrically. With electronic transducer elements, it is challenging to achieve wide bandwidths, high sensitivity, and small dimensions suitable for intracoronary imaging. Here we present an all-optical ultrasound (OpUS) transducer, which uses light within fibre-optics to generate and receive ultrasound. These devices have several distinguishing advantages, including the potential to generate and receive wideband ultrasound (tens of MHz) required for high resolution imaging. The side-viewing OpUS transducer is highly miniaturised (< 1.5 mm diameter) with two optical fibres for transmission and reception, and a rotational mechanism for circumferential imaging. The transmitter is a composite of carbon nanotubes and PDMS coated on a multimode fibre tip. Ultrasound is generated within this coating by the photoacoustic effect. The receiver comprises a concave Fabry-Perot cavity on a single mode fibre tip. Images acquired with the OpUS transducer were characterised using wire phantoms and post-mortem vascular tissue with stents. The axial resolution of this device was less than 70 microns, and the sensitivity was found to be sufficient to resolve pathological features. Subsequently, imaging was conducted in a healthy swine model in vivo and pulsatile motions of the artery were visualised with high fidelity. These studies show the strong potential for all-optical ultrasound to guide minimally invasive surgery.

Percutaneous coronary interventions are widely performed minimally invasive procedures used to treat narrowing (stenosis) of arteries in the heart. Differential blood pressure measurements across a stenosis are invaluable to estimate the prognostic benefit of performing angioplasty and stenting via calculation of the fractional flow reserve. Achieving stable measurements from within pressure microcatheters and guidewires that are compatible with stenosed vessels, and which can be fabricated with low cost manufacturing methods, remains an important challenge. We have developed all-optical pressure and temperature sensors with a single optical fibre and sensing element. This approach provides simultaneous temperature and pressure measurements in a highly miniaturised device, with a simple construction method using low cost materials. Polymeric structures including membranes and domes are applied to the distal ends of single mode optical fibres. Temperature and pressure changes induce time-varying displacements of these structures, which are monitored using phase-resolved low-coherence interferometry. Phase measurements are acquired at 250 Hz with a sensitivity of approximately 0.2 rad/°C for temperature measurements between 20 and 45°C, and approximately 0.08 rad/mmHg for pressure between 760 and 1060 mmHg. In vivo studies in arteries and hearts of sheep and swine indicate that the sensors have sufficient sensitivity and speed for measurement of physiological pressure waveforms in clinical settings. We will discuss the integration of these sensors within medical devices, and the potential for providing additional physiological parameters with the same devices.