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Introduction and objectivesPatients with pulmonary arteriovenous malformations (PAVMs) are at high risk of cerebral abscess with life-changing morbidity and mortality. These patients often concurrently have hereditary haemorrhagic telangiectasia (HHT). A recent study of patients with PAVMs/HHT at a single institution suggested several environmental associations with cerebral abscess, particularly dental care, higher iron intake, and long-haul flights.1For example, 4/37 (10.8%) cerebral abscess patients reported their abscess occurred after long-distance travel.MethodsIn order to capture data on wider exposure of this population to such risk factors, an online questionnaire was developed using Survey Monkey. In total, 139 non-biassed questions gathered data online about an individual’s HHT and/or PAVM phenotype, and environmental factors of relevance to cerebral abscess and other study foci in our group. With ethical approval (16/LO/1909), participants were recruited following advertisement through global HHT support networks.ResultsThe survey opened on 31 st May 2017. Within 7 weeks, 449 patients with self-reported HHT had completed the questionnaire. The majority (≥60%) were North Americans, with Europeans constituting the second largest group. 229 (51%) had PAVMs, usually diagnosed in their twenties to fifties. 89/229 (38.9%) had been treated by PAVM embolization and 13 (5.7%) by surgery. 17 (7.42%) had experienced a cerebral abscess and 46 gave a family history of cerebral abscess. Preliminary analysis of long-distance travel data revealed most patients rarely travelled for ≥3 hours. 266 participants reported the number of flights they had taken in their lifetime of durations<4 hours, 4–8 hours and ≥8 hours. In total, an estimated 27,722 hours were flown giving a mean average of 122 hours, i.e., approximately 10 long-distance flights per lifetime.ConclusionsThis survey provides a large dataset from individuals with PAVMs/HHT, captured without a bias toward flight usage as in flight-specific surveys. The data suggest long-distance travel is less common than previously thought for the HHT population, which adds greater weight to the previously published association[1] between long-distance travel and cerebral abscess risk. This approach should enable the development of better tools to predict and reduce the risk of cerebral abscess for these patients.ReferenceBootheret al. Clin Infect Dis2017, Apr 19. doi:10.1093/cid/cix373

Introduction and ObjectivesPatients with pulmonary arteriovenous malformations (PAVMs) are difficult to assess for anaesthetic risks. Generally, they display well-preserved exercise tolerance, yet may have very low oxygen saturation due to their anatomical intrapulmonary right-to-left shunts. During pre-operative assessments in the general population, anaerobic threshold and peak VO2, measured by cardiopulmonary exercise testing (CPET), are increasingly recommended to identify high-risk patients, and appropriately plan post-operative management. For example, “high-risk” for major abdominal surgery has been suggested as an anaerobic threshold <11 ml min-1kg-1and peak VO2<20 ml min-1kg-1.MethodsIn order to evaluate “pre-operative” risk categories for PAVM patients, anaerobic threshold and peak VO2, measured by ethically approved research cardiopulmonary exercise tests, were evaluated.Results26 PAVM patients underwent research CPET evaluations between April 2011-May 2017. Their median age was 57 years (interquartile range (IQR): 42–66). 16 (61.5%) were male. The median oxygen saturation (SaO2) was 92% (IQR: 88–95) and median haemoglobin 15.6 g/dl (IQR: 14.2–16.6). Overall, the PAVM group achieved a median 92% of the predicted maximum work (IQR: 67–106), anaerobic threshold ranged from 7.6–24.5 ml min-1kg-1(median: 12.35; IQR: 9.5–17.35), and peak VO2ranged from 11.2–45.5 ml min-1kg-1(median: 19.8; IQR: 16.7–28.4). Anaerobic threshold placed 11/26 (42.3%) in the suggested high-risk category for major abdominal surgery. In this group, the anaerobic threshold ranged from 7.6–10.8 ml min-1kg-1. Similarly, peak VO2 placed 14/26 (53.8%) in a high-risk category. Their peak VO2ranged from 11.2–16.5 ml min-1kg-1. There was full concordance between the categories determined by the 2 measurements. Notably, 6 patients were retested 3–31 months after embolization treatment resulting in increased SaO2. However, there was no increase in anaerobic threshold or peak VO2, and the 3 patients from this group initially in a higher risk category remained.ConclusionAnaerobic threshold and peak VO2suggest high proportions of PAVM patients are in a high-risk pre-operative risk category. The data suggest an important role for anaesthetic assessments. Noting that 1 in 2600 people are estimated to have PAVMs, further study is recommended to develop appropriate clinical guidance, and allocate resources to optimise care.

IntroductionPatients with pulmonary arteriovenous malformations (PAVMs) usually have underlying hereditary haemorrhagic telangiectasia (HHT), when iron deficiency often develops due to recurrent nasal and gastrointestinal haemorrhage. Iron deficient PAVM/HHT patients have more ischaemic strokes and venous thromboemboli. However, recent UK data indicate that cerebral abscesse are more common in PAVM patients using intravenous iron and/or with high normal transferrin saturation index.1Furthermore,~1 in 20 HHT patients report that iron treatments exacerbate their nosebleeds.2The goal of this study was to evaluate clinical patterns of iron treatments in patients with PAVMs and HHT.MethodsIron, red cell and microbiology indices were evaluated as part of routine clinic assessments of patients with PAVMs and/or HHT. With ethical approval, all available patient datasets between 04/2015 and 07/2017 were recorded, categorised according to patient status, and analysed using STATA IC v13 (Statacorp, Texas).ResultsAt first assessment, 72 patients were using oral iron alone, and 21 were using intravenous iron +/-iron tablets. As noted in figure 1, intravenous iron users had lower haemoglobin concentrations than oral iron users, despite higher serum ferritin. None of the 16 selected PAVM patients evaluated had positive blood cultures in the clinic, or developed positive cultures following ex vivoiron treatments. Three of seven selected patients had low serum haptoglobin (0.32–0.36 g/L, reference range 0.5–2.4 g/L) potentially indicative of shortened intravascular red cell survival. 31 patients were commenced on oral or intravenous iron, or recommended a dose increase, but 56 were advised dose reduction. Post assessment, daily iron dosages tended to be lower (elemental iron content 14–130, median 35 mg/day) than at first assessment (elemental iron content 14–260, median 65 mg/day, p=0.08). In two patients, external clinicians advised that iron dose reduction led to at least temporary cessation of blood transfusion requirements. Reported nosebleed improvements were common, though may have also been due to intervening treatment of PAVMs.2ConclusionsFurther study on the clinical efficacy and sequelae of iron treatments, and a more personalised approach to therapy, appears warranted in this patient group.ReferencesBoother, et al. Clin Infect Dis2017. doi:10.1093/cid/cix373Shovlin, et al. ERJ Open Res2016;2(2).00035–2016.

IntroductionIn a recent UK study, 61/497 (12.3%) of consecutive patients with pulmonary arteriovenous malformations (PAVMs) had experienced a clinical ischaemic stroke at median 46 (range 16–82) years.1Conventional stroke management included antiplatelet agents, but since many PAVM patients have underlying hereditary haemorrhagic telangiectasia (HHT), there has not been a blanket recommendation to treat all PAVM patients with such agents if residual PAVMs remain after maximal treatment. The goal of this study was to evaluate evidence of silent ischemia in patients with PAVMs.MethodsBetween 20/04/2009 and 02/12/2016, 43 individuals (20 males; 23 females) with known or suspected HHT underwent a cerebral MRI scan performed for the purpose of HHT cerebral AVM screening. All available scans were analysed by two independent neuroradiologists, blinded to patient demographics/PAVM status. Data were subsequently categorised and analysed using STATA IC v13 (Statacorp, Texas).ResultsPatient ages ranged from 17–74 (mean 42.2) years. Twenty-two (51.1%) were known to have PAVMs demonstrable by thoracic CT scan, and 21 had PAVMs excluded by CT scan. There was no age difference between the PAVM and non-PAVM cohorts (mean 43.3 [range 16–73] versus 41 [21–65] years respectively, p=0.46). No scan demonstrated a cerebral AVM, none provided evidence of prior cerebral haemorrhage, but only 22 (51.2%) of scans were reported as normal. 17 (81%) of patients without PAVMs had a normal scan, compared to 5 (22.7%) PAVM patients (p=0.0002). 15/21 (68.2%) PAVM patients had at least one infarct, and 6/21 (27.3%) had microangiopathic changes. The mean number of infarcts per PAVM patient was 1.58 compared to 0.14 in non-PAVM patients (p<0.0001). Intriguingly, while the rates of anterior circulation territory infarcts did not differ between PAVM and non-PAVM groups (patient means 0.36 and 0.14, p=0.18), the PAVM patients had more infarcts in posterior circulation territories (means 1.21 and 0, p<0.0001).ConclusionsThe findings identify high rates of silent cerebral ischaemic changes in patients with PAVMs, and raise the question whether all patients with persistent PAVMs after treatment should have pharmacological stroke prevention therapy, in the absence of a clinical stroke.ReferenceShovlinet al. PLOS One2014, Feb 19;9(2):e88812.