P737 Left ventricular hemodynamic forces: towards establishing reference values for healthy adults

Introduction

Left ventricular hemodynamic forces (LV-HDF) have been recently demonstrated to be promising markers of sub-clinical dysfunction and potential predictors of disease outcome. However, there is a lack of reference values in healthy subjects. Knowledge of physiologic ranges is mandatory towards the use of LV-HDF-based indices for disease assessment in future clinical applications.

Purpose

Aim of the current study is to define the normal reference values for LV-HDF parameters in a large cohort of healthy adults. Here we present preliminary results for the initial set of enrolled subjects.

Methods

We enrolled 82 healthy subjects [mean age 44 ± 13.2 years (range 18-88), 41 men]. All participants underwent standard transthoracic echocardiography (TTE) examination, as recommended by current guidelines, including apical two-, three- and four-chamber windows, acquired at a frame rate above 40 Hz. These were then analyzed by tri-plane tissue tracking, measuring LV volume and LV ejection fraction (EF) as reference parameters. The same tracking method was used to evaluate the global hemodynamic force by a novel mathematical calculation technique applied to the three-dimensional endocardial contour. Physical-based LV-HDF parameters were then extracted for clinical application; these included the amplitude (root mean square) of the longitudinal and transversal force components (FL and FT) and their alignment angle relative to the LV axis. Parameters were computed as average over the whole cardiac cycle as well as limited to the systolic phase. Forces were normalized with LV volume to reduce variability with LV dimension, and divided by specific weight to yield a dimensionless measure.

Results

Mean EF was 63 ± 9%. Whole cycle LV-HDF parameters were: FL = 16.0 ± 5.6%, FT = 2.3 ± 0.8%, with significant longitudinal alignment FT/FL = 0.15 ± 0.04, angle = 13.0°±3.1°. Systolic HDF parameters were: FL = 22.7 ± 8.2%, FT = 2.9 ± 1.1%, with longitudinal alignment FT/FL = 0.13 ± 0.04, angle = 11.2°±3.1°. Importantly, dimensionless physical-based LV-HDF parameters showed no significant variation with age, gender or BSA.

Conclusions

We report the physiologic range of LV-HDF parameters measured by TTE. Knowledge of age- and gender-specific reference values, for a combination of standard, mechanical and hemodynamic indices, can improve the global assessment of the LV function and may help to detect sub-clinical stages of LV dysfunction.

P1449 CMR-driven computational modeling of right ventricular flow dynamics

Introduction

The analysis of intracardiac blood flow patterns can significantly contribute to improve the understanding and treatment of cardiovascular disease. In contrast to the substantial literature on the left side of the heart, there is currently a significant lack of knowledge about the fluid mechanics of the right heart – pulmonary circulation unit (RH-PCU), both in healthy and diseased conditions.

Purpose

It is conjectured that computational modeling can be a key element to enhance current imaging techniques and provide quantitative insights into the unique RH-PCU biomechanics. Here we present a novel methodology that allows personalized numerical simulations of right heart flows, through a proper combination of cardiac magnetic resonance (CMR) with computational fluid dynamics (CFD).

Methods and results

We developed a patient-specific pipeline from medical images to computational models, as depicted in the figure. First, the RV geometry is reconstructed from time-resolved CMR cine images, comprising short-axis and longitudinal slices of the heart, where feature-tracking techniques are used to extract the motion of the RV endocardium contours. A time-continuous description of the moving geometry is obtained through an image-registration algorithm based on diffeomorphic mappings. The moving model of the RV, including the outflow tract and proximal pulmonary arteries, is finally fed to a dedicated CFD solver. The tool is able to provide a detailed description of the velocity and pressure fields inside the right ventricle and proximal pulmonary arteries during all phases of the cardiac cycle. From these fields, global hemodynamic quantities such as vortex properties, kinetic energy, pressure gradients and hemodynamic forces can be computed.

Conclusions

CMR-driven computational modeling of intra-ventricular flow enables a promising approach for understanding and evaluating the biomechanical environment of the right heart. This high-fidelity framework can be applied to investigate the RV response and adaptation to abnormal pressure and/or volume load conditions. It can also be used to reproduce the virtual flow that would realize in hypothetical conditions, and therefore adds predictive capabilities to modern flow imaging. The analysis may allow to determine an association between blood flow patterns and disease progression, and ultimately lead to derive and validate imaging biomarkers of clinical significance.

Abstract P1449 Figure. Pipeline for patient-specific modeling

Influenza vaccination in health-care workers: an evaluation of an on-site vaccination strategy to increase vaccination uptake in HCWs of a South Italy Hospital

Despite the international recommendation and specific programs, and although the vaccination of health-care workers (HCWs) is considered the main measure to prevent nosocomial influenza, vaccination coverage (VC) among HCWs remains low. One of the most important barriers to vaccination uptake is the time required to attend a vaccination clinic. Centers for Disease Control and Prevention (CDC) recommends on-site influenza vaccination as a proven and cost-effective strategy that increases productivity, reduces overall absenteeism and prevents direct health-care costs. In order to increase vaccine compliance in the HCWs, the Hygiene and the Occupational Medicine departments of Bari Policlinico General University-Hospital, in the 2017/18 influenza season, promoted an on-site vaccination program in eight Operative Units (OUs). We investigated the influenza VC among HCWs of Bari Policlinico (n = 3,397), comparing VC after implementation of the on-site strategy by the Hygiene department during the 2017/18 influenza season to VC in 2016/17 season. For 2017/18 season, we also compared VC in OUs target of on-site strategy with data from in eight "control" Units (choose by simple random sampling) not included in the on-site offer. In the 2016/17 influenza season, 295/3,397 HCWs were vaccinated (VC: 8.7%) while in the 2017/18 season 482 HCWs (VC: 14.2%) received the vaccination. In OUs target of on-site vaccination, 71 HCWs (VC: 10.0%) were vaccinated in the 2016/17 season and 126 (18.0%) in the 2017/18 season, of which 101/126 (80.2%) were vaccinated in an on-site clinic. VC in OUs target of on-site vaccination increased between 2016/17 and 2017/18 seasons of 16.8 ± 10.4% (range: 5.5-37.1), while the coverage in OUs of the control group increased of 1.6 ± 2.2% (range: -1.7-4.5), with a significant difference (p < .05). Our study suggests that the offer of on-site vaccination during the 2017/18 season led to an increase of VC in HCWs compared to the classical vaccination clinic approach. The determinants of adhesion and not-adhesion must be analyzed in dept, to experiment, in the future, new good clinical practices to increase the vaccination coverage in HCWs.

Enantioselective Synthesis of Cyclobutenes by Intermolecular [2+2] Cycloaddition with Non-C2 Symmetric Digold Catalysts

The enantioselective intermolecular gold(I)-catalyzed [2+2] cycloaddition of terminal alkynes and alkenes has been achieved using non-C2-chiral Josiphos digold(I) complexes as catalysts, by the formation of the monocationic complex. This new approach has been applied to the enantioselective total synthesis of rumphellaone A.

α,β-Unsaturated Gold(I) Carbenes by Tandem Cyclization and 1,5-Alkoxy Migration of 1,6-Enynes: Mechanisms and Applications

1,6-Enynes bearing OR groups at the propargyl position generate α,β-unsaturated gold(I)-carbenes/ gold(I) stabilized allyl cations that can be trapped by alkenes to form cyclopropanes or 1,3-diketones to give products of α-alkylation. The best migrating group is p-nitrophenyl ether, which leads to the corresponding products without racemization. Thus, an improved formal synthesis of (+)-schisanwilsonene A has been accomplished. The different competitive reaction pathways have been delineated computationally.

Synthesis of Rumphellaone A and Hushinone by a Gold-Catalyzed [2 + 2] Cycloaddition

The enantioselective total synthesis of rumphellaone A has been accomplished in 12 steps via a diastereoselective gold(I)-catalyzed [2 + 2] macrocyclization of a 1,10-enyne as the key step to build the cyclobutene moiety. This concise approach has also led to the total synthesis of husinone.

Anatomy of gold catalysts: facts and myths

This review article covers the main types of gold(i) complexes used as precatalysts under homogeneous conditions in organic synthesis and discusses the different ways of catalyst activation as well as ligand, silver, and anion effects.