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Funding Acknowledgements Type of funding sources: None. Background A computational fluid-dynamics (CFD) model previously developed with the aim of evaluating cardioembolic risk in patient affected by atrial fibrillation (AF) was used for the characterization of the left atrium (LA) hemodynamic in normal subjects (NL), patients affected by paroxysmal atrial fibrillation (PAR-AF) and patients affected by persistent atrial fibrillation (PER-AF). Based on the fluid-dynamics simulations results, we aimed at enhancing differences in blood flow in AF patients and NL and at better understanding the relationship between AF progression and stroke risk on a patient-specific basis. Methods 3D patient-specific anatomical and motion models were derived from ECG-gated coronary artery CT acquired with retrospective protocol. These models represented the computational domain for CFD simulations in which inflow initial conditions were derived from PW Doppler at the mitral valve and at the pulmonary veins. Velocity field and vortex structures both within the LA and left atrial appendage (LAA) were assessed in 10 NL, 5 PAR-AF and 4 PER-AF. Blood stasis was evaluated by populating the LAA with 500 particles and counting the number of particles still present after five cardiac cycles. Results Velocities inside the LA and in the LAA presented different amplitude and distribution in the 3 groups (peak velocity – NL: 50÷60 cm/s, PAR-AF: 40÷50 cm/s, PER-AF: 15÷25 cm/s). The mean velocity resulted lower in the PER-AF compared with PAR-AF (mean velocity – PAR-AF: 25÷35 cm/s, PER-AF: 8÷20 cm/s) at the LAA ostium and inside the LAA, in which the wash-out effect was strongly reduced (Figure 1). On the other hand, the mean velocity in the NL was higher with respect of AF patients (mean velocity – NL: 40÷45 cm/s). A higher number of vortex structures was observed in NL compared with AF patients, thus favouring the hypothesis of a more efficient wash-out of the LA and of the LAA. Blood stasis in terms of number of particles in the LAA after five cardiac cycles confirmed these results (NL: 5±2, PAR-AF: 18±3, PER-AF: 41±10). Conclusions The developed approach quantifies differences in LA hemodynamic between AF and NL patients, also allowing a stratification of the atrial disease progression in terms of variations in the blood velocity, organization of blood flow and quantification of blood stasis.

The subsequent waves of the COVID-19 pandemic in Italy had a major impact on cardiac care.A survey to evaluate the dynamic changes in arrhythmia care during the first five waves of COVID-19 in Italy (first: March-May 2020; second: October 2020-January 2021; third: February-May 2021; fourth: June-October 2021; fifth: November 2021-February 2022) was launched.A total of 127 physicians from arrhythmia centers (34% of Italian centers) took part in the survey. As compared to 2019, a reduction in 40% of elective pacemaker (PM), defibrillators (ICD), and cardiac resynchronization devices (CRT) implantations, with a 70% reduction for ablations, was reported during the first wave, with a progressive and gradual return to pre-pandemic volumes, generally during the third-fourth waves, slower for ablations. For emergency procedures (PM, ICD, CRT, and ablations), recovery from the initial 10% decline occurred in most cases during the second wave, with some variability. However, acute care for atrial fibrillation, electrical cardioversions, and evaluations for syncope showed a prolonged reduction of activity. The number of patients with devices which started remote monitoring increased by 40% during the first wave, but then the adoption of remote monitoring declined.The dramatic and profound derangement in arrhythmia management that characterized the first wave of the COVID-19 pandemic was followed by a progressive return to the volume of activities of the pre-pandemic periods, even if with different temporal dynamics and some heterogeneity. Remote monitoring was largely implemented during the first wave, but full implementation is needed.

BackgroundHealthcare workers (HCW) are at increased risk of being infected with SARS-CoV-2, yet limited information is available on risk factors of infection.MethodsWe pooled data on occupational surveillance of 10,654 HCW who were tested for SARS-CoV-2 infection in six Italian centers. Information was available on demographics, job title, department of employment, source of exposure, use of personal protective equipment (PPE), and COVID-19-related symptoms. We fitted multivariable logistic regression models to calculate odds ratios (OR) and 95% confidence intervals (CI).FindingsThe prevalence of infection varied across centers and ranged from 3.0% to 22.0%, being strongly correlated with that of the respective areas. Women were at lower risk of infection compared to men. Fever, cough, dyspnea and malaise were the symptoms most strongly associated with infection, together with anosmia and ageusia. No differences in the risk of infection were detected between job titles, or working in a COVID-19 designated department. Reported contact with a patient inside or outside the workplace was a risk factor. Use of a mask was strongly protective against risk of infection as was use of gloves. The use of a mask by the source of exposure (patient or colleague) had an independent effect in reducing infection risk.

In atrial fibrillation the correct identification of both presence and location of rotors during the ablation procedure could support the physician to optimize therapy administration. In this study we developed a tool that allows testing the capability of mapping catheters of detecting AF drivers with different shapes and in different acquisition conditions. Wave propagation was obtained using a monodomain implementation and a modified Courtemanche model. Two commercial catheters were simulated (Advisor™ HD Grid and PentaRay®). Our framework allowed the acquisition of the signal in unipolar mode at and to assess the effect of the influence of catheter inter-electrode spacing, coverage and endocardium-LA wall distance for rotor detection. In contact with the wall and within 1 mm distance from the real core all the configurations allowed a correct detection of the rotor, irrespective of geometry, coverage and inter-electrode distance. Increasing the interelectrode distance causes the incapability of rotor detection at a closer distance from the LA wall in the HD grid. The tool was effective in assessing how catheter geometry and specific parameters affect its capability to detect rotors. In the future, other catheter morphologies and different design parameters and acquisition conditions will be investigated.

Cardiac resynchronization therapy (CRT) is an effective treatment for chronic symptomatic systolic heart failure with cardiac dyssynchrony, but about 1/3 of patients do not respond favorably to the therapy. We hypothesized that acute modifications of the coronary sinus (CS) pacing cathode movements induced by biventricular pacing may be related to resynchronization process and consequently may carry predictive power on CRT response. A method for the 3D reconstruction of CS lead's pacing cathode trajectory (3DTJ) throughout a cardiac cycle showed that trajectory's geometry suddenly changed in responders (R) upon starting of biventricular pacing, becoming less eccentric and more multi-directional. Our multicenter observational study aimed at evaluating the clinical value of 3DTJ. Out of 119 patients enrolled, 50 have ended follow-up and have been analyzed. Concordance between 3DTJ metrics and response was 82% overall (41/50), 91% in R (31/34), 62% in NR (10/16). The proposed 3DTJ metric showed high sensitivity (91%) with specificity=62%; PPV=84%, NPV=77%. From our data, 3DTJ seems a promising tool to acutely predict CS pacing site-specific response to CRT. Its investigational use as an intra-operatory, real-time guidance for selecting LV pacing sites may open new opportunities for CRT patients' selection and therapy delivery.

Computational fluid dynamics represents a valuable non-invasive approach to determine and assess physically meaningful parameters in a complex fluid dynamics system represented by AF. The aim of this study was the design, development and test of different LA motion fields in AF on a patient-specific 3D anatomical model to clarify the influence of contraction models on LA hemodynamics. Since LA motion field is not available from clinical data during AF, three displacement models were designed to simulate the irregular, disorganized, very rapid and strongly reduced LA contraction, a random model, a discrete random model and a con-tinuous sinusoidal model. Blood velocity fields, kinetic energy, vortex structures and blood stasis were analyzed in both SR and AF conditions in the LA. Velocities in SR were higher than in AF, particular-ly during atrial systole. The three AF models resulted in different wash-out velocities both at the mitral valve and at the ostium of the LA appendage. Vortices were also differently distributed inside the LA showing a more organized flow in the sinusoidal model which was also characterized by the lowest blood stasis (8.6%) inside the LA appendage. Overall, different LA de-formation models in AF affect LA hemodynamics and additional studies should be performed to develop a realistic contraction model to simulate AF episodes.

This paper offers both a theoretical framework and empirical evidence on the role that the two gravity forces, namely market size and geographical distance, have indirectly through imports,\ud on firms’ exports patterns. The model shows that sourcing from bigger and closer markets implies higher productivity gains which, in turn, increase firms’ ability to enter export market,\ud as well as their export value. Exploiting data on product and destination-level transactions of a large panel of Italian firms, the paper shows that, on average, the indirect effects of the\ud gravity forces are about one third of their direct effects.

Review of physical processes of the atmosfere in Arctic