A Numerical Model to Predict the Relaxation Phenomena in Thermoset Polymers and Their Effects on Residual Stress during Curing-Part I: A Theoretical Formulation and Numerical Evaluation of Relaxation Phenomena.

This paper analyzes the effect of crosslinking reactions on a thermoset polymer's viscoelastic properties. In particular, a numerical model to predict the evolution of epoxy's mechanical properties during the curing process is proposed and implemented in an Ansys APDL environment. A linear viscoelastic behavior is assumed, and the scaling of viscoelastic properties in terms of the temperature and degree of conversion is modeled using a modified version of the TNM (Tool-Narayanaswamy-Mohynian) model. The effects of the degree of conversion and structural relaxation on epoxy's relaxation times are simultaneously examined for the first time. This formulation is based on the thermo-rheological and chemo-rheological simplicities hypothesis and can predict the evolution of epoxy's relaxation phenomena. The thermal-kinetic reactions of curing are implemented in a homemade routine written in APDL language, and the structural module of Ansys is used to predict the polymer's creep and stress relaxation curves at different temperatures and degrees of conversion.

Three-dimensional Transesophageal Echocardiography in Infective Endocarditis: What Does It Add?

Infective endocarditis (IE) diagnosis is based on a clinical suspicion supported by consistent microbiological and instrumental data. Evidence of involvement of cardiac valves (native or prosthetic) or prosthetic intracardiac material is a major diagnostic criterion of IE. Transthoracic echocardiography (TTE) is the initial technique of choice for the diagnosis while transesophageal echocardiography (TEE) is recommended in patients with an inconclusive or negative TTE, in patients with high suspicion of IE, as well as in patients with a positive TTE, in order to document local complications. Repeating TTE and/or TEE should be considered during follow-up of uncomplicated IE, in order to detect new silent complications and monitor vegetation size. In the setting of IE, the role of three-dimensional (3D) TEE is increasing; in fact, this technique has also been shown to be useful for the diagnosis of IE and its complications as it allows to obtain infinite planes and volumetric reconstructions. In this review, we will describe the usefulness of 3D-TEE and its added value in the management of IE.

CRT implantation after transvenous lead/device extraction (TLE) in a patient with COVID-19: Endocarditis triggered by syndrome coronavirus 2 (SARS-COV-2) infection? A case report.

In the era of coronavirus disease 2019 (COVID-19), the management of cardiac implantable electronic devices infections with concomitant viral infection has not been completely defined yet. In this explorable context, we report the first experience of a Cardiac resynchronization therapy with defibrillator (CRT-D) implantation after transvenous lead extraction for endocarditis in a COVID-19 patient. We describe both the measures and procedures implemented to reduce the cross-infection in the operating room and our clinical practice to improving procedure effectiveness on patient care.

Right ventricular-arterial uncoupling independently predicts survival in COVID-19 ARDS.

AIM: To investigate the prevalence and prognostic impact of right heart failure and right ventricular-arterial uncoupling in Corona Virus Infectious Disease 2019 (COVID-19) complicated by an Acute Respiratory Distress Syndrome (ARDS). METHODS: Ninety-four consecutive patients (mean age 64 years) admitted for acute respiratory failure on COVID-19 were enrolled. Coupling of right ventricular function to the pulmonary circulation was evaluated by a comprehensive trans-thoracic echocardiography with focus on the tricuspid annular plane systolic excursion (TAPSE) to systolic pulmonary artery pressure (PASP) ratio RESULTS: The majority of patients needed ventilatory support, which was noninvasive in 22 and invasive in 37. There were 25 deaths, all in the invasively ventilated patients. Survivors were younger (62 ± 13 vs. 68 ± 12 years, p = 0.033), less often overweight or usual smokers, had lower NT-proBNP and interleukin-6, and higher arterial partial pressure of oxygen (PaO2)/fraction of inspired O2 (FIO2) ratio (270 ± 104 vs. 117 ± 57 mmHg, p < 0.001). In the non-survivors, PASP was increased (42 ± 12 vs. 30 ± 7 mmHg, p < 0.001), while TAPSE was decreased (19 ± 4 vs. 25 ± 4 mm, p < 0.001). Accordingly, the TAPSE/PASP ratio was lower than in the survivors (0.51 ± 0.22 vs. 0.89 ± 0.29 mm/mmHg, p < 0.001). At univariate/multivariable analysis, the TAPSE/PASP (HR: 0.026; 95%CI 0.01-0.579; p: 0.019) and PaO2/FIO2 (HR: 0.988; 95%CI 0.988-0.998; p: 0.018) ratios were the only independent predictors of mortality, with ROC-determined cutoff values of 159 mmHg and 0.635 mm/mmHg, respectively. CONCLUSIONS: COVID-19 ARDS is associated with clinically relevant uncoupling of right ventricular function from the pulmonary circulation; bedside echocardiography of TAPSE/PASP adds to the prognostic relevance of PaO2/FIO2 in ARDS on COVID-19.

Effect of Triple Combination Therapy With Lopinavir-Ritonavir, Azithromycin, and Hydroxychloroquine on QT Interval and Arrhythmic Risk in Hospitalized COVID-19 Patients.

INTRODUCTION: No data are provided about the effect of triple combination therapy with Lopinavir/Ritonavir (LPN/RTN), hydroxychloroquine (HQ) and azithromycin (AZT) on corrected QT (QTc) interval and arrhythmic risk, in COVID-19 patients. This study aims to describe the incidence of extreme QTc interval prolongation among COVID-19 patients on this experimental treatment and to identify the clinical features associated with extreme QTc prolongation. MATERIALS AND METHODS: Data of 87 COVID-19 patients, treated with triple combination including LPN/RTN, HQ and AZT, were analyzed. QT interval was obtained by the tangent method and corrected for heart rate using Bazett's formula. Extreme QTc interval prolongation was considered an absolute QTc interval ≥ 500 ms or an increase in QTc intervals of 60 ms or greater (ΔQTc ≥ 60 ms) compared with baseline. RESULTS: Hypertension (66.7%) and diabetes (25.3%) were the most prevalent cardiovascular comorbidities. Twenty patients (23%) showed extreme QTc interval prolongation; no clinical, electrocardiographic or pharmacological characteristics have been associated to extreme QTc prolongation, except the history of ischemic stroke (P= 0,007). One torsade de pointes (TdP) in patient with QTc extreme prolongation (QTc: 560 ms) after 5 days of therapy was recorded. CONCLUSIONS: We observed a high incidence of extreme QTc interval prolongation among COVID-19 patients on triple combination therapy. Since the incidence of malignant arrhythmias seems to be not negligible, a careful electrocardiographic monitoring would be advisable.

Association of Adams-Oliver syndrome with pulmonary arterio-venous malformation in the same family: a further support to the vascular hypothesis.

Adams-Oliver syndrome (AOS) is a rare disease characterized by congenital scalp defects, terminal transverse limb defects and cutis marmorata telangiectatica. A significant incidence of cardiac and vascular malformations has been reported, leading to the hypothesis of a vascular defect early involved in the pathogenesis. We report two members of the same family with previously diagnosed AOS based on clinical phenotype and later recognized to have pulmonary arterio-venous malformation (PAVM). None of the subjects fulfilled current diagnostic criteria of hereditary hemorrhagic telangiectasia, which is the most common cause of PAVM. The occurrence of PAVM in AOS lends support to the hypothesis that endothelial specific abnormalities could be a patho-physiological mechanism in its development. Therefore, the role of screening for PAVM in clinical management of subjects with AOS should deserve further studies.