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Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): MPL received the Catalan Society of Cardiology Research Grant in 2019 and 2020 (Catalonia, Spain); the Josep Font Grant (2019-2022) from Hospital Clínic Barcelona (Catalonia, Spain). Background Left bundle branch pacing (LBBP) has emerged as an alternative to biventricular pacing. However, lack of a systematic stepwise application of the left bundle branch (LBB) capture criteria complicates implantation. Objective To define a stepwise application of LBBP capture criteria that will simplify implantation and ensure LBB capture. Methods A cohort of 24 patients from the LEVEL-AT trial who received LBBP and had electrocardiographic imaging (ECGI) at 45 days post-implant were included. The usefulness of ECG and electrogram based criteria to predict accurate LBB capture were analyzed. A two-step approach was developed to ensure LBB capture. The gold standard used to confirm LBB capture was the change in ventricular activation pattern and shortening in left ventricular activation time, assessed by ECGI. Results Twenty-two (91.6%) patients showed LBBP capture on ECGI. All patients fulfilled pre-screwing requisites: lead in septal position in left-oblique projection and W paced morphology in V1. In the first step, presence of either right bundle branch conduction delay pattern (qR or rSR in V1) or left bundle branch capture Plus (QRS ≤120ms) resulted in 95% sensitivity and 100% specificity to predict LBB capture, with an accuracy of 95.8%. In the second step, the presence of selective capture (100% specificity, only 41% sensitivity) or a spike-R Conclusions Stepwise application of ECG and electrogram criteria ensured an accurate assessment of left conduction system capture.

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This project has received funding from the European Union's Horizon Research and Innovation Programme under the Marie-Sklodowska Curie Grant Agreement No. 860974 Background Recurrence rates after atrial fibrillation (AF) ablation are still unsatisfactory. As catheter ablation is primarily targeting pulmonary vein (PV) ectopic activity, it is not surprising that extra-PV arrythmogenic substrate is a key determinant of arrhythmia recurrence. Against this background, several studies have proposed assessment of extra-PV substrate in terms of atrial fibrosis or locally reduced conduction velocities (CV) to guide treatment. However, to date no non-invasive method directly assessing electrical arrhythmogenic substrate has been established in clinical practice, and treatment decisions are commonly based on crude surrogates like AF type or left atrial size. Here we establish and validate a novel non-invasive method based on electrocardiographic imaging (ECGi) to determine atrial arrhythmogenic substrate in terms of reduced local CVs and its predictive value regarding arrhythmia recurrence after PVI. Methods and results 52 consecutive patients scheduled for AF ablation (PVI-only) and 19 healthy controls were prospectively included and received ECGi to assess left and right atrial arrhythmogenic substrate. This ECGi-based method uses 64 electrodes placed on the torso. Subsequently, a 3D model of the torso is acquired as an anatomical reference using a 3D reconstruction camera. A personalised 3D atrial geometry is then derived from a database of human atria using an artificial intelligence-based algorithm. Finally, unipolar surface electrograms are projected onto the cardiac geometry and local CVs are estimated. Mean ECGi-determined atrial CVs were significantly lower in AF patients than in healthy controls, both in a global analysis (1.45±0.15 m/s vs. 1.64±0.15 m/s; p A ROC analysis revealed that a cut-off for this variable of 0.72 m/s best discriminates PVI responders from non-responders: patients with a mean CV >0.72 m/s in all atrial regions showed a 6-months arrhythmia-free survival of 90.9%, whereas patients with one or more atrial regions with a mean CV Conclusion This was the first study to investigate local atrial CV non-invasively and to validate their predictive value regarding outcome after PVI. The absence of ECGi-determined areas of slow conduction well discriminated PVI responders from non-responders. Such non-invasive assessment of electrical arrhythmogenic substrate may guide treatment strategies and be an important step towards personalised AF therapy.

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported by the European Union NextGenerationEU/PRTR. Background – The non-invasive characterization of complex atrial tachyarrhythmias, including atrial flutter (AFL) and focal atrial tachycardia (AT) is challenging. Conventional 12-lead electrocardiogram (ECG) faces several limitations. Planning a precise and preprocedural strategy for complex tachyarrhythmias catheter ablation (CA) is not easy. Purpose To evaluate the diagnostic capacity of a novel electrocardiographic imaging (ECGI) system that does not require previous CT/MRI thoracic imaging. Methods – 42 patients (27 males, CHA2DS2-VASc score 2±1, LVEF 54.5 ± 11.0 % and LA area 31.3 ± 7.0 cm2) undergoing CA for focal AT or AFL were prospectively included in the study. A preprocedural ECGI was managed based on a 64-electrode vest, a torso reconstruction using a 3D real-time acquisition camera, and an artificial intelligence-based method to estimate the patient atrial geometry. The differential diagnostic capacities of non-invasive 12-lead ECG and ECGI were assessed compared with endocavity electroanatomical mapping (EAM) regarding three endpoints: 1) the identification of the involved atrial cavity, 2) the mechanism (focal/micro-reentry or macro-reentry), and (3) the ablation target site defined as the area where the earliest activation was located for focal/micro re-entrant arrhythmias, and the precise anatomical pathway for macro re-entrant tachyarrhythmias. Regarding the ECG, the three endpoints were assessed based on validated algorithms by 2 different observers blinded from the diagnosis. Results – 48 atrial tachyarrhythmias of which 59.5% occurred in the context of a history of CA were evaluated. The non-invasive characterization of complex atrial arrhythmias using this novel ECGI system was possible in 94% of the cases (Figure A): directly for 36 arrhythmias and after decreasing ventricular response using vagal maneuvers for 9. ECGI obtained global accuracy to identify the involved atrial cavity of 91.7%, the mechanism of 89.6%, and the ablation target of 83.3%. In challenging cases, such as in patients with history of CA for AF (n = 27) and in patients without a final diagnosis of counterclockwise typical AFL (n=38) the diagnosis capacity of ECGI is consistent compared to the whole study population. The ECGI diagnostic capacity significantly outclassed the ECG one regarding the identification of the involved cavity (p Conclusions (Figure B) – This novel non-invasive ECGI system that does not require CT/MRI thoracic imaging accurately characterizes complex atrial tachyarrhythmia and outclasses ECG, the current noninvasive diagnostic tool of reference.

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): CATCH ME: Characterizing Atrial fibrillation by Translating its Causes into Health Modifiers in the Elderly Background We recently demonstrated that in human atria, endomysial fibrosis causes conduction disturbances during atrial fibrillation (AF), while overall connective tissue content (over-all fibrosis) has no effect. Etiological and molecular determinants of endomysial fibrosis are largely unknown. Methods We quantified over-all and endomysial atrial fibrosis using staining with WGA in left (LA, n=95) and right (RA, n=76) atrial appendages sampled from a European cohort (CATCH ME) of patients undergoing cardiac surgery. The contributions of AF, heart failure (HF), sex, age, and 4 principal components accounting for confounding clinical characteristics to over-all and endomysial fibrosis were determined in a multivariate model. RNA sequencing was performed to explore biological pathways associated with the two types of fibrosis. Results Over-all and endomysial fibrosis were moderately correlated (LA: r=0.69, RA: 0.61, both p Conclusions Taken together, female sex, HF, and AF are the main drivers of fibrosis in human atria. However, endomysial fibrosis is independently associated with AF whereas over-all fibrosis is not. BMP10 is a specific marker of endomysial fibrosis. Our findings suggest that distinct mechanisms are involved in the development of over-all versus endomysial fibrosis in human atria and may provide an explanation for the recently reported predictive value of BMP10 biomarkers levels for AF recurrences after AF ablation and for stroke.

Funding Acknowledgements Type of funding sources: None. Background A new functional mapping strategy based on targeting deceleration zones (DZs) has become one of the most commonly used strategies within the armamentarium of substrate-based ablation methods for ventricular tachycardia (VT) in patients with structural heart disease. The classic conduction channels detected by voltage mapping can be accurately determined by cardiac magnetic resonance (CMR). Objectives To analyze the evolution of DZs during ablation and their correlation with CMR. Methods Forty-two consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-December 2020) were included (medium age 65.3±11.8 years; 94.7% male; 73.7% ischemic heart disease). Baseline DZs and their evolution in isochronal late activation remaps were analyzed. A comparison between DZs and CMR conducting channels (CMR-CCs) was realized. Patients were prospectively followed for VT recurrence for one year. Results Overall, 95 DZs were analyzed, 93.68% of which were correlated with CMR-CCs: 44.8% located in the middle segment and 55.2% located in the entrance/exit of the channel. Remapping was performed in 91.7% of patients (1remap: 33.3%, 2remaps: 55.6% and 3remaps: 2.8%). Regarding the evolution of DZs, 72.2% disappeared after the first ablation set, with 14.13% not ablated at the end of the procedure. A total of 32.5% of DZs in remaps correlated with a CMR-CCs already detected, and 17.5% were associated with an unmasked CMR-CCs. One-year VT recurrence was 22.9%. Conclusions DZs are highly correlated with CMR-CCs. In addition, remapping can lead to the identification of hidden substrate initially not identified by electroanatomic mapping but detected by CMR.

Funding Acknowledgements Type of funding sources: None. Introduction Abnormalities of cardiac activation and conduction velocity (CV) are known pro-arrhythmogenic factors. Electrocardiographic imaging (ECGI) is presented as a non-invasive tool for arrhythmogenic substrate analysis. However, electrocardiographic features such propagation activation patterns, and CV are unknown in healthy subjects. In this study, ECGI technology has been evaluated for ventricular tissue stratification in patients with and without structural heart disease. Methods Nineteen patients were included in the study. The healthy ventricles group (Panel A) included 10 patients (8 males, 57 ± 6 years, NYHA = I and LVEF 61 ± 5 %) with normal baseline QRS and normal values of ventricular morphology, function and perfusion assessed by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). The structural heart disease group (Panel B) included 9 patients (9 males, 66±6 years, NYHA 2±1 and LVEF 26±5%) with ischemic cardiomyopathy (ICM) confirmed by LGE-CMR and indication for ablation due to ventricular tachycardia. For each patient, fibrotic areas were identified by ventricular segmentation of the LGE-CMR and ventricles were regionalized in 16 regions. Epicardial electrograms were noninvasively reconstructed by ECGI, late activation time (LAT) and CV maps were calculated to study electrocardiographic features. Results – Ventricles with fibrosis secondary to ICM revealed heterogenous activation patters and higher activation time distribution compared to healthy ventricles (120 ms vs 80 ms; p Conclusions ECGI can noninvasively identify fibrotic tissue by analysing ventricular activation and CV patterns. ECGI could be a potential early tool to identify patients at risk of sudden cardiac death.

Funding Acknowledgements Type of funding sources: None. Background Radiofrequency ablation (RF) is a well-established treatment for of premature ventricular complexes (PVCs) It is not uncommon to perform radiofrequency ablation of PVCs arising from epicardial/intramural localization, in particular those arising from the LV summit and aortic sinuses of Valsalva. Purpose The aim is to investigate safety, efficacy, and outcome of PVCs radiofrequency ablation through a non-endocardial approach including high power and long duration RF applications. Methods We defined Non-Endocardial Radiofrequency Ablation (NERA) a procedure in which at least one RF site has been identified into the coronary venous system, aortic sinuses of Valsalva, inter-leaflet triangle or pulmonary cusps. We selected the study population from a series of consecutive patients who underwent radiofrequency ablation of PVCs from January 2017-May 2022, in whom at least one RF application has been realized according to the definition. Results During the study period, 399 patients underwent PVCs RF and 46 fulfilled the inclusion criteria (age: 59±13 years; 33, 72% males; mean LVEF:46±12%, mean PVC burden 26±10 %). The total number of NERA sites was 55: 15(27%) coronary venous system, 9(16%) right coronary cusp, 10(18%) left coronary cusp, 18 (33%) interleaflet triangle between right and left coronary cusp and 3 (5%) left pulmonary cusp. In 18 (39%) patients a multisite ablation was performed. Mean power during RF was 37±9 W (15-50) with median of 40W. Mean duration of single RF was 88±72 seconds (30-304) (median: 58 seconds). In 63% of the patients high power (40W or more) and in 55% long duration (>60 seconds) application was delivered in at least one of the ablation spots. Procedural success was achieved in 37 patients (80%). No complications related with RF site were observed. Multisite RF was significantly associated with procedural failure (OR 8,27; CI 1,48– 46,31; p=0,01). During follow up, mean PVCs burden was 7,3±9%, with a mean and median burden reduction (Δ) of 69±41% and 96%. The rate of event-free survival was 69%. Multisite RF and coronary venous system RF were predictors of recurrence (HR 3,81; 95% CI 1,14–12,66; p=0,02 and HR 3,88; 95% CI 1,23 – 12,27; p=0,01), while procedural success was protective (HR 0.1; CI 0.03 - 0.33, p < 0.001). After multivariate Cox proportional hazard analysis, coronary venous system RF was associated with higher VA recurrences during follow up (HR 2.71, CI 0.83 - 8.85, p= 0,09), while procedural success confirmed his protective role (HR 0.13, CI 0.04-0.42, p < 0,001). Conclusion Radiofrequency ablation from non-endocardial sites is a safe and effective procedure, even using high power and/or long duration RF. Nevertheless long term outcomes are still characterized by a recurrence rate higher than in purely endocardial PVC ablation.

Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Catalan Society of Cardiology; Asociación del Ritmo Cardiaco (Spanish Society of Cardiology). Background Correction of dyssynchrony measured with echo strain, in conduction system pacing (CSP) vs biventricular pacing (BIVP) has not been reported. Objectives Our purpose was to compare echocardiographic dyssynchrony correction and strain improvement during follow-up between CSP and BIVP. Methods A treatment received analysis was performed in patients (n=29 CSP; BIVP 40). Patients were evaluated at baseline (ON and OFF programming) and at 6 and 12 months. All echocardiograms were completed by operators blinded to the type of device implanted. Intraventricular (septal flash), interventricular (difference between left and right ventricular outflow times), and auriculoventricular (diastolic filling time) dyssynchrony, as well as strain parameters (septal rebound, global longitudinal strain (GLS), and Risum pattern (typical left bundle branch block contraction pattern)) were analyzed. Results 32% (22/69) were women; baseline LVEF was 27.5% (7% SD) and left ventricular end-systolic volume (LVESV) 138ml (77ml SD) without differences between groups. At the 12-month follow-up, there were no differences in CSP vs. BIVP in LVEF (45.8% (10% SD) vs. 42.7% (12% SD), p=0.25) and LVESV (81.5 ml (41 ml SD) vs. 101.7 ml (56 ml SD), p=0.08). Longitudinal analyses showed that the improvement of all echocardiographic dyssynchrony parameters over time was similar between groups (p Conclusions CSP and BIVP provided a similar dyssynchrony and strain correction over time. Acute strain correction predicted ventricular remodeling at 12 months follow-up.

Funding Acknowledgements Type of funding sources: None. Background Cardiac magnetic resonance has demonstrated to accurately identify voltage conduction channels and it is nowadays an important tool to analyze the arrhythmic substrate, to predict ventricular tachycardia (VT) events and to aid VT ablation. The characteristics of CMR channels (CMR-CCs) that predicts the presence of deceleration zone (DZ) have not been explored. Methods Forty-four consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-July 2021) were included (medium age 64.8±11.6 years; 95.5% male; 70.5% ischemic heart disease, mean ejection fraction of 32.3±7.8). Characteristics of CMR-CCs were analyzed and correlation with DZs both in baseline maps and remaps were performed. Patients were prospectively followed for VT recurrence for one year. Results Overall, 129 automatically detected CMR-CCs were analyzed (2.89±1.83 per patient; length: 52.72±65.44mm (0.18–376.73), CC mass: 1.76±2.46grams (0.01–14.59); protectedness 19.02±24.51% (0.01–143.51)). Overall, 73.6% of CMR-CCs were associated with a DZ: 58.1% CMR-CCs in baseline map and 15.5% with a DZs not observed initially but in remaps. The univariate analysis showed that channels associated with DZs were longer (61.83±73.43 vs. 29.96±32.55, OR 1.01, p0.004), with higher border zone mass (2.02±2.75 vs. 1.09±1.44, OR 1.28, p0.031) and more protectedness (21.90±27.23 vs. 11.46±14.20, OR1.02, p0.036). VT recurrence after one-year follow up was 21.95%. Conclusions Pre ablation CMR can accurately identify channels that correlates with DZs that could be targets for ablation, especially those CMR-CCs with higher length, border zone mass and protectedness. Additionally, some channels not related with DZ in the first map have a clear DZ after abolishing the first region of slow conduction, suggesting a very useful role of CMR to detect potential DZs.

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): CATCH ME: Characterizing Atrial fibrillation by Translating its Causes into Health Modifiers in the Elderly Background Atrial cardiomyopathy is emerging as independent prognostic factor in cardiovascular disease. Fibrotic remodeling, cardiomyocyte hypertrophy and a reduction in capillary density are histological hallmarks of atrial cardiomyopathy. The contribution of etiological factors to atrial cardiomyopathy has not been robustly quantified. Purpose To quantify the relation between histological features of atrial cardiomyopathy and the clinical profile of patients. Methods We examined left (LA, n=91) and right (RA, n=75) atrial appendages sampled from a European cohort of patients undergoing cardiac surgery. Quantification of histological cardiomyopathy features was performed a recently developed and validated imaging analysis algorithm following myocardial triple staining with wheat germ agglutinin (WGA), CD31 and vimentin. The contributions of AF, heart failure (HF), sex, age, and 4 principal components accounting for confounding clinical characteristics to over-all and endomysial fibrosis were determined in a multivariate model. K-means clustering of 6 atrial histological features was performed to identify different types of remodeling. Results LA samples showed less fibrosis (p Samples clustered into 2 distinct clusters. One cluster showed fibrotic cardiomyopathy, with more endomysial (p Conclusions Fibrotic cardiomyopathy is associated with female sex, persistent AF and heart failure while hypertrophic cardiomyopathy more often occurs in men. More research is needed to establish whether treatment of AF and heart failure prevents the development of atrial cardiomyopathy.

BackgroundAtrial cardiomyopathy (AtCM) is emerging as an independent prognostic factor in cardiovascular disease. Fibrotic remodeling, cardiomyocyte hypertrophy, and capillary density are histological hallmarks of atCM. However, the contribution of various etiological factors and atrial fibrillation (AF) to the development of differential atCM phenotypes has not been robustly quantified. We aimed to evaluate the association between histological features of atCM and the clinical phenotype.MethodsWe examined left (LA, n=95) and right (RA, n=76) atrial appendages sampled from a European cohort of patients undergoing cardiac surgery. Quantification of histological atCM features was performed using the JavaCyte algorithm, following staining with agglutinin (WGA), CD31 and vimentin. The contributions of AF, heart failure (HF), sex and age to histological characteristics were determined in a multivariate model. K-means clustering of 6 histological features was performed to identify different types of atCM.ResultsIn both LA and RA, persistent AF was associated with increased endomysial fibrosis (LA:+1.07±0.41µm,p=0.01; RA:+0.89±0.43µm,p=0.032), whereas total extracellular matrix (ECM) content was unchanged in AF. Men had larger cardiomyocytes (LA:+1.87±0.72μm,p=0.012), while women had a higher degree of endomysial fibrosis (LA:+0.99±0.51µm,p=0.048). Heart failure patients showed more endomysial fibrosis (LA:+1.79±0.41µm,pConclusionsAtCM phenotypes vary with patient characteristics. Fibrotic atCM is associated with female sex, persistent AF and heart failure, while hypertrophic features are more common in men.

Background and Goal of Study: Blood salvage (BS) is important to implement the second pillar of Patient Blood Management to avoid anaemia after total knee arthroplasty (TKA). Our primary outcome was to assess BS usefulness to decrease allogenic blood transfusion (ABT) rate in TKA. Materials and Methods: a retrospective, observational cohort study was conducted on consecutive patients scheduled for TKA with BS or not. Demographic, comorbidity, surgical and anesthetic data, laboratory pre and postoperative results, volume of blood drained, and reinfused from BS and the requirement of ABT were recorded. Parametric and non-parametric tests were employed. p< 0.05 was accepted as significant. Results: 260 patients were included (130 per cohort). The amount of postoperative bleeding was 713.1 +445.4 ml. 26.5% received ABT. BS reduced transfusion in 13,1% (p=0,024) with RR 1,65 (CI 1,085-2,52)]. Risk factors for postoperative bleeding were: male gender, atrial fibrillation, preoperative anti-platelet therapy and cementless primary TKA. Risk factors for ABT: ASA > II, preoperative hemoglobin < 13 g/dl, knee revision, anti-platelet therapy, longer surgery time. Patients transfused had lower hemoglobin values (p

Background Recent MRI-based studies have raised great concern about frequent cardiac involvement even in mild or asymptomatic COVID-19. However, while signs of myocardial injury were found in large proportions of patients after COVID-19, all studies published to date lack baseline imaging and are therefore unable to discriminate between pre-existing and COVID-19-induced injury. Purpose In this longitudinal study, we aimed to assess the true cardiac impact of COVID-19 based on pre- and post-COVID-19 late gadolinium enhancement (LGE)-MRI. Methods A prospective registry of patients with serial LGE-MRIs was screened for patients with documented SARS-COV-2 infection after cardiac LGE-MRI. Eligible patients then received a post-COVID-19 LGE-MRI using the same scanner and sequence as in the pre-COVID-19 MRI. Inversion recovery prepared T1-weighted gradient echo sequences were acquired in sinus rhythm using ECG gating and a free-breathing 3D navigator, 15–20 minutes after administering an intravenous bolus of 0.2 mmol/kg of gadobutrol. A TI scout sequence was used in order to determine the optimal TI that nullified the left ventricular myocardial signal. The presence of LGE was independently assessed qualitatively by two experienced investigators blinded to patient information. For quantitative analyses a 3D-reconstruction of the left ventricle was performed using ADAS-3D software. LGE was then automatically quantified based on a prespecified signal intensity threshold of ≥3 SD above the mean of a remote non-enhanced myocardial region. Results Pre- and post-COVID LGE-MRI from 31 patients with cardiovascular risk factors that had recovered from mild to moderate COVID-19 (23% hospitalised) were analysed. At a median of 5 months post-COVID-19, LGE-lesions indicative of myocardial injury were encountered in 15 out of 31 patients (48%), which is in line with previous reports. However, intraindividual comparison with the pre-COVID-19 MRI reveiled all of these lesions as pre-existing and thus not COVID-19-related. Quantitative analysis detected no increase in the size of individual LGE-lesions, nor in the global left ventricular LGE-extent. There was no difference in any functional or structural parameter between pre- and post-COVID-19 MRI. Conclusion This longitudinal study in a cohort of patients considered at high risk of cardiac involvement, did not find any evidence for COVID-19-induced myocardial injury. The complete absence of de novo LGE lesions in this cohort is reassuring and indicates that cardiac sequelae of COVID-19 are rare and certainly not as common as previously suggested. Funding Acknowledgement Type of funding sources: None.

Introduction Compelling evidence supports that regular moderate exercise has a positive impact on cardiovascular disease (CVD) incidence and prognosis [1]. Nevertheless, emerging clinician and experimental data in healthy individuals suggests that long-term, high-intensity endurance exercise might increase vascular stiffness and enhance coronary calcification [2,3]. In patients with CV risk factors, it has been hypothesized that the beneficial effects of strenuous exercise on risk factors could outweigh its deleterious effects, but this remains unproven [4]. Purpose To analyze how increasing doses of exercise impinge on the vascular system in a murine model of aged rats with metabolic syndrome and kidney disease. Methods Seven-week-old male Zucker obese rats, a metabolic syndrome model, were subjected to left nephrectomy. At 26 weeks of age, rats were assigned to a sedentary (SED), moderate intensity (MOD, 15 cm/s, 40 min/day), or high intensity (INT, 25 cm/s, 60 min/day) group, and trained 5 days/week for 10 weeks. An echocardiogram and a glucose tolerance test were performed 24 hours after the last training bout. At sacrifice, vascular reactivity was assayed in the descending thoracic aorta, and EC50 calculated for every experiment. Expression of oxidant and antioxidant mRNA markers was analyzed in thoracic perivascular adipose tissue (tPVAT). Cytokines levels (TNFα, IL10, IL6, Selectin, ICAM1 and Adiponectin) were analyzed in plasma samples. Results Rats in the INT group had a significantly lower body weight (10.99±0.35 g/mm vs 12.23±0.58 g/mm) and a higher heart weight (32.44±0.72 mg/mm vs 31.28±0.78 mg/mm), indexed by tibia length, than the SED group. Both MOD and INT exercise improved glucose tolerance compared with SED (Fig 1a). On echocardiography, INT rats presented with LV septum hypertrophy and dilation, mildly reduced ejection fraction and fractional shortening compared with SED. Aortic diameter was also increased in the INT group (3.62±0.11 mm vs 3.25±0.13 mm). In vascular reactivity assays, the MOD group showed improved endothelial function, indicated by a larger carbachol-induced relaxation than SED and INT (Fig. 1b). However, MOD and INT were no longer different after adding the antioxidant Tempol (Fig1c). No differences were found in tunica media fibrosis amongst the groups (19.12±0.45%; 26.97±2.52%; 25.98±2.14%). In tPVAT, the mRNA expression of prooxidants (NOX2, p47) was higher, and antioxidant markers (SOD2, GCH1) was lower in the INT group than MOD and SED (Fig. 2). TNFα levels were higher in plasma of INT rats than SED. Conclusion In a rodent model, both intense and moderate exercise improved the CV risk profile, but only moderate training improved vascular function. Oxidative stress may, at least partially, account for the lack of benefits of intensive exercise. Our results suggest that the deleterious effects of strenuous physical activity could persist even in individuals with CV risk factor. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fondo de Investigaciόn Sanitaria (FIS), Instituto de Salud Carlos III

Background Electrical reconnection of pulmonary veins (PV) is considered an important determinant of recurrent atrial fibrillation (AF) after PV isolation (PVI). However, it requires an invasive repeat procedure to assess durability of PVI. Against this background, in most centers clinically relevant AF recurrences almost automatically trigger repeat ablation procedures aiming at PV re-isolation. However, technological and procedural advances have substantially improved efficacy of catheter ablation. As a result it is increasingly common that all four PVs are found isolated in those repeat procedures. Thus, as ablation of extra-PV targets has failed to show benefit in large randomized trials, more and more often these highly invasive procedures are being performed only to confirm durable PVI. To date, late gadolinium enhancement (LGE)-MRI is the only non-invasive method to assess ablation lesions. However, its predictive value regarding PVI durability has not been systematically determined. Purpose Here we aim to define the ability of LGE-MRI to rule out PV reconnection and its potential to guide patient selection for repeat ablation procedures. Methods This study was based on our prospective registry where all patients receive an LGE-MRI before and after AF ablation. All patients that had undergone a repeat invasive procedure after an initial PVI-only ablation were included, and the ability of LGE-MRI to determine PVI durability was analysed using invasive mapping as a reference. Gradient echo MR sequences were acquired in sinus rhythm and 3D-reconstruction of left atrium and PVs performed using ADAS-3D software. LGE was quantified based on the signal intensity ratio of each voxel relative to the blood pool, applying a previously validated threshold of >1.2 to define LGE indicative of ablation-induced scarring. LGE discontinuations of >3 mm were considered indicative of PV reconnection. For validation, PVI durability was determined invasively based on local bipolar electrograms. Results A total of 142 patients and 284 PV pairs were analysed. LGE-MRI displayed LGE-discontinuations suggestive of PV reconnection in 210 PV pairs (74%). According to invasive mapping, LGE-MRI predicted PV reconnection with high sensitivity (89%), whereas specificity was somewhat lower (48%). Of note, a complete circumferential LGE-lesion reliably ruled out electrical reconnection of the respective PV pair with a negative predictive value of 94.5%. In the patient-based analyses 11% of the patients displayed complete LGE-lesion sets encircling all 4 PVs. None of these patients showed electrical PV reconnection in the invasive repeat procedure. Conclusion Although not frequently encountered, continuous LGE lesions encircling all 4 PVs reliably rule out PV reconnection. Thus, LGE-MRI has the potential to guide treatment decisions in patients with AF recurrences and may help to avoid unnecessary repeat procedures with all their associated risks and costs. Funding Acknowledgement Type of funding sources: None.

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union Horizon 2020 CATCH ME; Cardiovascular Research Netherlands RACE V Background Little is known about changes in the atrial transcriptome associated with paroxysmal and persistent atrial fibrillation (AF). Purpose To identify major molecular mechanisms in AF, we determined consistent differential expression (DE) between atrial tissue samples from well-characterized patients with paroxysmal or persistent AF and patients without a history of AF (no AF) in two independent patient cohorts. Methods Poly-A tailed RNA from left and right atrial appendage tissue samples from independent discovery and replication cohorts CATCH ME (n=192) and RACE V (n=122) was sequenced and analyzed according to patient AF history. Analyses were performed stratified by atrial side, adjusting for age, sex, heart failure and a combination of clinical characteristics determined by principal component analysis. Transcripts were considered DE in CATCH ME if their fold change reached transcriptome-wide significance (false discovery rate (FDR) < 0.05). DE transcripts in each rhythm comparison were replicated in RACE V if we observed a concordant direction of effect and a within-set FDR < 0.05 in the same comparison. Results Persistent AF compared to no AF was associated with 184 left atrial DE transcripts in CATCH ME of which 85 (46%) were replicated in RACE V, and with 208 right atrial DE transcripts in CATCH ME of which 86 (41%) were replicated in RACE V. Overall, 26 transcripts were discovered and replicated in both atria. Discovered but non-replicated transcripts often did exhibit concordant direction of effect (left: 78%, right: 83%). Replicated transcripts consisted of protein coding genes, antisense and non-coding RNAs. Protein coding genes showed involvement in pathways linking persistent AF to cardiomyocyte structure, conduction properties, fibrosis, inflammation, molecule trafficking, and endothelial dysfunction. Interestingly, paroxysmal AF was not consistently associated with DE transcripts in any comparison. Principal component analysis of the expression of the 26 transcripts strongly associated with persistent AF did however reveal a distinct paroxysmal AF expression profile in-between no AF and persistent AF patients in the first principal component scores (Figure 1). Conclusion RNA sequencing of human atrial tissue samples identified many transcripts associated with persistent AF in left and/or right atria, discovered and replicated using two independent cohorts. These consistent findings of AF-induced changes provide a starting point for targeted proteomic analysis and single-nucleus sequencing to further unravel the molecular mechanisms underlying AF progression to persistent AF, and biomarker development to quantify AF progression and enable precision medicine in individual patients.

Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Horizon 2020 Background Risk factors for atrial fibrillation (AF), such as ageing, heart failure and AF itself, enhance AF propensity partly by inducing atrial fibrosis. Atrial endomysial fibrosis, a type of reactive fibrosis occurring between cardiomyocytes, impairs transverse conduction in rapid atrial pacing animal models. The factors underlying transcriptional regulation of endomysial fibrosis are largely unknown. Objective To examine the contributions of age, sex, AF and heart failure to the development of endomysial fibrosis in the context of concurrent pathologies. To study genome-wide transcriptional changes associated with endomysial fibrosis in human left and right atrial appendage biopsies (LAA, n=95; RAA, n=76). Methods An algorithm for automated quantification of endomysial fibrosis following staining with wheat germ agglutinin (WGA) was employed. Linear mixed models were constructed to determine endomysial fibrosis quantity as a function of AF, heart failure, sex, age and four principal components that accounted for potential confounding effects of other clinical characteristics. RNA sequencing was used to study expression changes in the atrial transcriptome associated with endomysial fibrosis. Results Sex, persistent AF, heart failure and age were independently associated with endomysial fibrosis. We identified hundreds (LAA: 386, RAA: 311) of RNA transcripts associated with endomysial fibrosis. None of these associations were independent from the clinical phenotypes. However, explorative gene set enrichment analysis identified association of endomysial fibrosis with gene sets involved in extracellular matrix organization, immune response, cell motility, developmental processes, cardiac muscle contraction and proteostasis in LAA while in RAA only gene sets regulating contractile function were enriched. Conclusion Besides AF, female sex, age and heart failure are associated with endomysial fibrosis in the atria. While abundance of none of the differential genes were independently associated with endomysial fibrosis, gene set enrichment analysis suggests an involvement of extracellular matrix organization, immune response, cell motility, developmental processes and cardiac muscle contraction in endomysial fibrosis.

In January 2020, the first cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were reported in Europe. Multiple outbreaks have since then led to a global pandemic, as well as to massive medical, economic, and social repercussions. SARS-CoV-2 pneumonia can develop into acute respiratory distress syndrome (ARDS) when mechanical ventilation (MV) is needed (3, 4). ARDS produces abnormalities in gas exchange with a variable degree of shunt (5), high dead space ventilation (dead space volume [Vd]/tidal volume [Vt] ratio) (6), diminished pulmonary compliance (7), and alterations to the pulmonary circulation (8). The cornerstone of ARDS management is to provide adequate gas exchange without further lung injury as a result of MV. To date, information regarding the characteristics of SARS-CoV-2-induced ARDS is not completely known. However, this information is crucial to better apply MV and facilitate organ support strategies. We therefore present the characteristics of gas exchange, pulmonary mechanics, and ventilatory management of 50 patients with laboratory-confirmed SARS-CoV-2 infection, who developed ARDS and underwent invasive MV (IMV). Methods: Descriptive analysis included 50 consecutive patients with laboratory-confirmed SARS-CoV-2 infection who developed ARDS (9) and underwent IMV. These patients were admitted to the SARS-CoV-2-dedicated intensive care units (ICUs) at Hospital Clinic of Barcelona, Spain, between March 7 and March 25, 2020. Upon ICU admission, epidemiological characteristics, the severity of SARS-CoV-2 infection with the Acute Physiology and Chronic Health Evaluation II score, prognostic biomarkers of SARS-CoV-2 infection (described in Reference 4), time from hospital to ICU admission, time from ICU admission to intubation, oxygen therapy or noninvasive ventilation (NIV) use, and microbiology were investigated. On the day that criteria for ARDS diagnosis were met (9) and IMV was needed, the following assessments were performed: impairment in oxygenation was analyzed with the partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio, and abnormalities of CO2 metabolism were studied with the ventilatory ratio (VR), a surrogate parameter of Vd/Vt. In addition, adjunctive therapies and MV parameters related with ventilation-induced lung injury (VILI) described elsewhere (11-15) were investigated. Correlations of SARS-CoV-2 prognostic biomarkers (4), pulmonary mechanics, and gas-exchange data were performed. Twenty-eight-day and hospital mortality, ventilator- and ICU-free days at Day 28, hospital and ICU lengths of stay, and need for tracheostomy were also evaluated (16). Finally, a subanalysis assessing differences before and after prone positioning was performed. For additional detail on the method, see the online supplement. Results: By March 25th, 2020, 50 patients with laboratory-confirmed SARS-CoV-2 infection and ARDS had been admitted to our hospital. Table 1 shows the demographic and clinical characteristics of these patients. The median (interquartile range [IQR]) age was 66 (57-74) years. Thirty-six patients (72%) were men. Upon ARDS diagnosis, 44% of patients were initially classified as having moderate ARDS, whereas 24% were classified as having mild ARDS and 32% were classified as having severe ARDS. The outcomes of these patients are shown in Table 1. ICU and hospital lengths of stay were prolonged, and tracheostomy was performed in 30 (60%) patients. Hospital mortality was 34%.

Since the first description of the epidural technique during the 1920s, the continuous progress of knowledge of the anatomy and physiology of the epidural space has allowed the development of different techniques to locate this space while increasing both the safety and efficacy of the procedure. The most common techniques used today are based on the two main characteristics of the epidural space: the difference in distensibility between the ligamentum flavum and the epidural space, and the existence of negative pressure within the epidural space. However, over recent years, technological advances have allowed the development of new techniques to locate the epidural space based on other physical properties of tissues. Some are still in the experimental phase, but others, like ultrasound-location have reached a clinical phase and are being used increasingly in daily practice.

Resumen Desde la primera descripcion de la tecnica epidural en los anos 1920, el progreso continuo en el conocimiento de la anatomia y de la fisiologia del espacio epidural ha permitido desarrollar diferentes tecnicas de localizacion de este espacio para aumentar tanto la seguridad como la eficacia del procedimiento. Las tecnicas mas utilizadas hoy en dia se basan en las 2 principales propiedades descritas del espacio epidural: la diferencia de distensibilidad entre el ligamento amarillo y el espacio epidural y la existencia de una presion negativa en el espacio epidural. Sin embargo, en los ultimos anos, la evolucion tecnologica ha permitido desarrollar nuevas tecnicas de localizacion basadas en otras propiedades fisicas de los tejidos. Algunas de ellas estan todavia en una fase experimental, pero otras como las tecnicas con ultrasonidos han alcanzado una fase clinica y se esta expandiendo su uso en la practica diaria.

Introduction Neuromuscular blockade enables airway management, ventilation and surgical procedures. However there is no national consensus on its routine clinical use. The objective was to establish the degree of agreement among anaesthesiologists and general surgeons on the clinical use of neuromuscular blockade in order to make recommendations to improve its use during surgical procedures. Methods Multidisciplinary consensus study in Spain. Anaesthesiologists experts in neuromuscular blockade management (n = 65) and general surgeons (n = 36) were included. Delphi methodology was selected. A survey with 17 final questions developed by a dedicated scientific committee was designed. The experts answered the successive questions in two waves. The survey included questions on: type of surgery, type of patient, benefits/harm during and after surgery, impact of objective neuromuscular monitoring and use of reversal drugs, viability of a multidisciplinary and efficient approach to the whole surgical procedure, focusing on the level of neuromuscular blockade. Results Five recommendations were agreed: (1) deep neuromuscular blockade is very appropriate for abdominal surgery (degree of agreement 94.1%), (2) and in obese patients (76.2%); (3) deep neuromuscular blockade maintenance until end of surgery might be beneficial in terms of clinical aspects, such as immobility or better surgical access (86.1–72.3%); (4) quantitative monitoring and reversal drugs availability is recommended (89.1%); finally (5) anaesthesiologists/surgeons joint protocols are recommended. Conclusions Collaboration among anaesthesiologists and surgeons has enabled some general recommendations to be established on deep neuromuscular blockade use during abdominal surgery.

Resumen Introduccion El bloqueo neuromuscular facilita la manipulacion de la via aerea, la ventilacion y procedimientos quirurgicos, pero no hay un consenso a nivel nacional que facilite la practica clinica habitual. El objetivo fue conocer el grado de acuerdo entre anestesiologos y cirujanos sobre el uso clinico del bloqueo neuromuscular, para establecer recomendaciones de mejora de su empleo durante un procedimiento anestesico-quirurgico. Metodos Estudio de consenso multidisciplinar en Espana, que incluyo anestesiologos expertos en bloqueo neuromuscular (n = 65) y cirujanos generales (n = 36). Se utilizo metodologia Delphi. Cuestionario con 17 preguntas consensuado por un comite cientifico, al que respondieron los expertos en dos olas. El cuestionario incluyo preguntas sobre: tipo de cirugia, tipo de paciente, beneficios/perjuicios durante y despues de la cirugia, repercusion de la monitorizacion objetiva y del uso de farmacos reversores, la viabilidad de abordaje multidisciplinar y eficiente del procedimiento quirurgico, enfocado en el grado de bloqueo neuromuscular. Resultados Se establecieron cinco recomendaciones: 1) el bloqueo neuromuscular profundo es muy adecuado en cirugia abdominal (grado de acuerdo 94,1%), y 2) en pacientes con obesidad (76,2%); 3) el mantenimiento del bloqueo neuromuscular profundo hasta el final de la cirugia puede ser beneficioso en aspectos clinicos, como inmovilidad del paciente o mejor acceso quirurgico (86,1 y 72,3%); 4) la monitorizacion cuantitativa y la disponibilidad de reversores del bloqueo neuromuscular es recomendable (89,1%); 5) se recomiendan protocolos de actuacion conjuntos entre anestesiologos y cirujanos. Conclusiones La colaboracion entre anestesiologos y cirujanos generales, ha permitido establecer una serie de recomendaciones genericas sobre el uso de bloqueo neuromuscular profundo en cirugia abdominal.

Resumen El Ministerio de Sanidad (MSSSI) aprobo (abril de 2013) el proyecto denominado «Compromiso por la Calidad de las Sociedades Cientificas en Espana», en respuesta a la demanda social y profesional por la sostenibilidad del sistema de salud. La iniciativa se enmarca en las actividades de la Red Espanola de Agencias de Evaluacion de Tecnologias y Prestaciones, del Sistema Nacional de Salud, y esta coordinado de forma conjunta por la Subdireccion General de Calidad y Cohesion, por el Instituto Aragones de Ciencias de la Salud (IACS), y por la Sociedad Espanola de Medicina Interna (SEMI). A este Proyecto se han incorporado todas las sociedades cientificas de nuestro pais, y su objetivo principal es disminuir la utilizacion de intervenciones sanitarias innecesarias, con el fin de acordar recomendaciones de «no hacer», basadas en la evidencia cientifica. Nuestro objetivo primario fue identificar intervenciones que no han demostrado eficacia, tienen efectividad escasa o dudosa, no son coste-efectivas o no son prioritarias. Los objetivos secundarios fueron: la reduccion de la variabilidad en la practica clinica, la difusion entre medicos y pacientes para orientar en la toma de decisiones, el uso adecuado de los recursos sanitarios y, por ultimo, la promocion de la seguridad clinica y la reduccion de la iatrogenia. El proceso de seleccion de las 5 recomendaciones de «no hacer» se realizo mediante la metodologia Delphi. 25 panelistas (todo anestesiologos) eligieron entre 15 propuestas basadas en: evidencia de calidad que la sustenta, relevancia o impacto clinico de la misma y poblacion a la que afecta. Las 5 recomendaciones propuestas fueron: No mantener niveles profundos de sedacion en pacientes criticos sin una indicacion especifica; No realizar radiografia preoperatoria de torax en pacientes menores de 40 anos con estado fisico ASA I o II; No realizar, de manera sistematica, pruebas preoperatorias en cirugia de cataratas, salvo indicacion basada en historia clinica y exploracion fisica; No programar cirugia electiva con riesgo de hemorragia en pacientes con anemia hasta realizar estudio diagnostico y tratamiento adecuados; y No realizar pruebas de laboratorio (hemograma, bioquimica y estudio de coagulacion) en pacientes sanos o con enfermedad sistemica leve (ASA I y II) previo a cirugias de bajo riesgo, con perdida estimada de sangre minima.

In April 2013 the Ministry of Health (MSSSI) adopted the project called "Commitment to Quality by Scientific Societies in Spain", in response to social and professional demands for sustainability of the health system. The initiative is part of the activities of the Spanish Network of Agencies for Health Technology Assessment and Services of the National Health System, and is coordinated jointly by the Quality and Cohesion Department, the Aragon Institute of Health Sciences (IACS), and the Spanish Society of Internal Medicine (SEMI). All the scientific societies in Spain have been included in this project, and its main objective is to reduce the unnecessary use of health interventions in order to agree "do not do" recommendations, based on scientific evidence. The primary objective was to identify interventions that have not proven effective, have limited or doubtful effectiveness, are not cost-effective, or do not have priority. Secondary objectives were: reducing variability in clinical practice, to spread information between doctors and patients to guide decision-making, the appropriate use of health resources and, the promotion of clinical safety and reducing iatrogenesis. The selection process of the 5 "do not do" recommendations was made by Delphi methodology. A total of 25 panellists (all anaesthesiologists) chose between 15 proposals based on: evidence that supports quality, relevance, or clinical impact, and the people they affect. The 5 recommendations proposed were: Do not maintain deep levels of sedation in critically ill patients without a specific indication; Do not perform preoperative chest radiography in patients under 40 years-old with ASA physical status I or II; Do not systematically perform preoperative tests in cataract surgery unless otherwise indicated based on clinical history and physical examination; Do not perform elective surgery in patients with anaemia at risk of bleeding until a diagnostic workup is performed and treatment is given; and not perform laboratory tests (blood count, biochemistry and coagulation) prior to surgery in healthy or low risk patients (ASA I and II) with minimal estimated blood loss.

In April 2013 the Ministry of Health (MSSSI) adopted the project called "Commitment to Quality by Scientific Societies in Spain", in response to social and professional demands for sustainability of the health system. The initiative is part of the activities of the Spanish Network of Agencies for Health Technology Assessment and Services of the National Health System, and is coordinated jointly by the Quality and Cohesion Department, the Aragon Institute of Health Sciences (IACS), and the Spanish Society of Internal Medicine (SEMI). All the scientific societies in Spain have been included in this project, and its main objective is to reduce the unnecessary use of health interventions in order to agree "do not do" recommendations, based on scientific evidence. The primary objective was to identify interventions that have not proven effective, have limited or doubtful effectiveness, are not cost-effective, or do not have priority. Secondary objectives were: reducing variability in clinical practice, to spread information between doctors and patients to guide decision-making, the appropriate use of health resources and, the promotion of clinical safety and reducing iatrogenesis. The selection process of the 5 "do not do" recommendations was made by Delphi methodology. A total of 25 panellists (all anaesthesiologists) chose between 15 proposals based on: evidence that supports quality, relevance, or clinical impact, and the people they affect. The 5 recommendations proposed were: Do not maintain deep levels of sedation in critically ill patients without a specific indication; Do not perform preoperative chest radiography in patients under 40 years-old with ASA physical status I or II; Do not systematically perform preoperative tests in cataract surgery unless otherwise indicated based on clinical history and physical examination; Do not perform elective surgery in patients with anaemia at risk of bleeding until a diagnostic workup is performed and treatment is given; and not perform laboratory tests (blood count, biochemistry and coagulation) prior to surgery in healthy or low risk patients (ASA I and II) with minimal estimated blood loss.

Resumen Objetivos El objetivo principal fue conocer las motivaciones que han determinado la eleccion de la especialidad en Anestesiologia y Reanimacion en la Comunidad de Madrid y determinar si el conocimiento o contacto previo con la especialidad contribuia a la eleccion de la misma, ver si existian diferencias en las motivaciones principales del grupo que elige la especialidad por primera vez, con respecto a los que lo hacen como segunda especialidad y saber cuales eran sus expectativas y si estas se habian cumplido, ademas de conocer el grado de satisfaccion global. Material y metodos Encuesta dirigida a todos los residentes de Anestesiologia y Reanimacion de la Comunidad de Madrid entre noviembre de 2008 y febrero de 2010. La encuesta incluia datos demograficos, especialidad previa, contacto pregraduado, motivos de eleccion (tecnicos, sociales, laborales, satisfaccion obtenida y expectativas cumplidas). Resultados Se obtuvieron 89 encuestas validas (35% de repuestas). Los aspectos mas frecuentemente valorados fueron: el desarrollo y realizacion de tecnicas (97,8%), el concepto de especialidad dinamica y con amplio contenido teorico practico (98,9%), la valoracion y el tratamiento del paciente critico (93,3%). Asimismo estas tres razones las consideraron entre importantes y muy importantes en la valoracion cuantitativa por la mayoria de los encuestados, siendo lo mas importante para el 55,8% la realizacion y desarrollo de tecnicas. El 100% de los que tenian especialidad previa, se definieron insatisfechos. El conocimiento previo de la especialidad establece diferencias en las motivaciones e intereses, como el interes por el dolor (p = 0,037) o el modelo profesional a emular (p = 0,014). Conclusiones Lo que mas atrae a los residentes es el contenido teorico practico, la posibilidad de realizar tecnicas y la valoracion y tratamiento del paciente critico. Los residentes con otra especialidad estan menos satisfechos y sus expectativas menos cumplidas que el resto.

Resumen Objetivo El objetivo principal de este trabajo es evaluar la concordancia de los anestesiologos para la localizacion de algunas referencias anatomicas en anestesia regional. Material y metodos En encuesta anonima escrita, se pidio la localizacion de los dermatomas T5 y T10, linea de Tuffier (espacio L3–L4), espacio T7–T8 y C6–C7 sobre un dibujo anatomico. Interrogamos respecto a los anos de experiencia del anestesiologo, tipo de cirugia y bloqueo realizado con mas frecuencia, numero de bloqueos/ano/anestesiologo, comprobacion del nivel sensitivo, motor y ensenanza recibida. Se realizo un calculo de frecuencias relativas. La relacion entre anos de experiencia y numeros de bloqueos y numero de aciertos, se comparo mediante un test de Chi-cuadrado (SPSS 13.0). Resultados Incluimos 100 medicos (66 residentes y 34 de plantilla). El punto mejor localizado fue T10 (91,8%) y el peor T5 (38,1%). El 45% de los anestesiologos realiza entre 100 y 250 bloqueos neuroaxiales al ano. El bloqueo lumbar es el mas frecuentemente realizado (98% de anestesiologos). El 95% de los encuestados comprueba el nivel sensitivo y el 83% el nivel motor. El 94,8% utiliza la tecnica de frio-calor y el 81% la escala de Bromage. Parece que el numero de anos de experiencia no esta relacionado con el numero de aciertos (p = 0,76). Tampoco existe relacion entre el numero de bloqueos realizados y los aciertos en la localizacion (p = 0,2). Conclusiones La localizacion de los puntos de referencia es maxima para T10 y minima para T5, con oscilaciones en las marcas anatomicas de hasta 4 dermatomas.

Massive obstetric hemorrhage still remains a major cause of maternal mortality and morbidity. The risk factors associated with this pathology must be identified in order to schedule the appropriate delivery with the necessary resources. A case is presented of an iliac artery occlusion with intravascular balloons for suspected placenta accreta during cesarean section. The perioperative treatment, as well as an analysis of the treatment options is described, along with their advantages and disadvantages, from the use of postpartum hemorrhage protocols, blood transfusion and procoagulant factors, and other maneuvers to control bleeding, until the hysterectomy.