RAMAN-SCATTERING FROM ELECTRONIC EXCITATIONS IN PERIODICALLY DELTA-DOPED GAAS

We report photoluminescence and Raman scattering measurements of periodically δ-doped Si : GaAs. The spectra of short-period structures are similar to those of uniformly doped material, but new lines appear in the Raman spectra of longer-period structures that arise from inter-subband transitions between confined electron levels in a single δ-layer or between minibands in the δ-doping superlattice. © 1990

Infective endocarditis without biological inflammatory syndrome: Description of a particular entity

Background: Bacterial infective endocarditis (IE) is rarely suspected in patients with a low C-reactive protein (CRP) concentration. Aims: To address the incidence, characteristics and outcome of left-sided valvular IE with low CRP concentration. Methods: This was a retrospective analysis of cases of IE discharged from our institution between January 2009 and May 2017. The 10% lowest CRP concentration (< 20 mg/L) was used to define low CRP concentration. Right-sided cardiac device-related IE, non-bacterial IE, sequelar IE and IE previously treated by antibiotics were excluded. Results: Of the 469 patients, 13 (2.8%; median age 68 [61–76] years) had definite (n = 8) or possible (n = 5) left-sided valvular IE with CRP < 20 mg/L (median 9.3 [4.7–14.2] mg/L). The median white blood cell count was 6.3 (5.3–7.5) G/L. The main presentations were heart failure (n = 7; 54%) and stroke (n = 3; 23%). Transthoracic echocardiography (TTE) showed vegetations (n = 5) or isolated valvular regurgitation (n = 4). Overall, eight patients (62%) had severe valvular lesions on transoesophageal echocardiography (TOE), and nine patients (69%) underwent cardiac surgery. All patients survived at 1-year follow-up. Bacterial pathogens were documented in eight patients (streptococci, coagulase-negative Staphylococcus, Corynebacterium jeikeium, HACEK group, Coxiella burnetii, Bartonella henselae) using blood cultures, serology or valve culture and/or polymerase chain reaction analysis. Conclusions: Left-sided valvular IE with limited or no biological syndrome is rare, but is often associated with severe valvular and paravalvular lesions. TOE should be performed in presence of unexplained heart failure, new valvular regurgitation or cardioembolic stroke when TTE is insufficient to rule out endocarditis, even in patients with a low CRP concentration

Characterization of 18-Fluorodeoxyglucose Uptake Pattern in Infective Endocarditis After Transcatheter Aortic Valve Implantation

n/

Timing of aortic valve replacement in high-gradient severe aortic stenosis: impact of left ventricular ejection fraction

Background: Patients with high-gradient (HG) severe aortic stenosis (AS) and left ventricular (LV) dysfunction are at high risk of death. The optimal timing for aortic valve replacement (AVR) is not defined by guidelines. The objective was to define the optimal timing to perform isolated AVR in patients with HG-AS and severe LV dysfunction. Methods: We retrospectively included 233 consecutive patients admitted for severe HG-AS (aortic valve area <1cm2 and mean gradient ≥40mmHg). Severe LV dysfunction was defined by LV ejection fraction ≤35% (LVEF). All-cause mortality while waiting for AVR and after the intervention (30 days) was compared in patients with (n = 28) and without (n = 205) LVEF ≤35%. Results: Patients with HG-AS and severe LV dysfunction had a higher risk profile than those with LVEF >35%. AVR was performed in 93% (218/233) of patients, 41% by surgery (SAVR) and 53% by transcatheter (TAVR). TAVR was the preferred method to treat HG-AS patients with LVEF ≤35%. All-cause mortality while waiting for AVR was higher in patients with severe LV dysfunction (22% vs. 2.0%, p < 0.001) and occurred within a shorter time (12 [8–26] days vs. 63 [58–152] days, p = 0.010) compared to those with LVEF >35%. All death in HG-AS patients with a severe LV dysfunction occurred within the first month. Postoperative mortality was low (1.3%), irrespective of LVEF. Conclusions: AVR should be performed promptly after Heart Team decision in patients with HG severe AS and LVEF ≤35% because of a very high and premature risk of death while waiting for intervention