Frédéric Maes

Watt-level erbium-doped all-fiber laser at 3.44 μm

We demonstrate a 3.44 μm all-fiber laser emitting a maximum of 1.5 W at room temperature, the highest continuous power ever generated from a mid-IR fiber oscillator clearly beyond 3 μm. The laser operates on the 4F(9/2)→4I(9/2) transition of erbium-doped fluoride glasses and relies on a dual pumping scheme at 974 and 1976 nm. By combining a dichroic mirror deposited on the input fiber tip and a fiber Bragg grating as an output coupler, a stable laser emission is produced with a FWHM bandwidth of less than 0.6 nm. The laser cavity has an efficiency of 19% with respect to the launched pump power at 1976 nm and no saturation is observed provided 974 nm co-pumping is sufficient. The joint effect of the two pumps is also investigated.

Meta-Analysis Comparing Single Versus Dual Antiplatelet Therapy Following Transcatheter Aortic Valve Implantation

To compare dual antiplatelet therapy (DAPT) versus single antiplatelet therapy (SAPT) as antithrombotic treatment after transcatheter aortic valve implantation (TAVI) for the prevention of ischemic events, vascular and bleeding events, and death. Data from the 3 randomized trials comparing DAPT versus SAPT post-TAVI were pooled and analyzed in a patient-level meta-analysis. The primary end point was the occurrence of death, major or life-threatening bleedings, and major vascular complications at 30-day follow-up. Events were adjudicated according to the Valve Academic Research Consortium 2 definitions. A total of 421 patients randomized to DAPT (210 patients) or SAPT (211 patients) post-TAVI were analyzed. There were no differences between groups in baseline clinical and procedural characteristics. The occurrence of the 30-day combined primary end point was higher in the DAPT group (17.6% vs 10.9%, odds ratio 1.73, 95% confidence interval 1.00 to 2.98, p = 0.050), with an increased rate of major or life-threatening bleeding events in the DAPT group (11.4% vs 5.2%, odds ratio 2.24, 95% confidence interval 1.12 to 4.46, p = 0.022). There were no differences between DAPT and SAPT groups in the incidence of death (5.2% vs 3.8%, p = 0.477), global ischemic events (3.8% vs 3.8%, p = 0.999), or stroke (2.4% vs 2.4%, p = 0.996). DAPT (vs SAPT) was associated with a higher rate of major adverse events after TAVI, mainly driven by an increased risk of major or life-threatening bleeding complications along with a lack of beneficial effect on ischemic events. These results do not support the current recommendation of DAPT as antithrombotic therapy after TAVI.

Feasibility and Safety of Early Repeat Transradial Access Within 30 Days of Previous Coronary Angiography and Intervention

Transradial approach (TRA) is the default access site for diagnostic angiography and intervention in many centers. Repeat ipsilateral radial artery access late after index procedure has been associated with failures. It is unknown whether early (≤30 days) and very early (<24 hours) repeat radial access is technically feasible and safe. Study population consisted of consecutive patients undergoing repeat (≥2) procedures within 30 days in a high-volume TRA center. Transradial access failure and resulting femoral approach was categorized as primary (no repeat attempt) or secondary (crossover). Timing of repeat access and reasons for failure were recorded. From November 2012 to December 2014, repeat catheterization by TRA was performed twice in 573 of 626 patients (92%) (median delay 4 [2 to 9] days), 3 times in 29 of 38 (76%) patients (median delay 15 [5 to 26] days), and 4 times in 1 patient within 21 days. When repeat catheterization occurred during the first 24 hours following the index procedure, 53% and 75% of patients had second and third procedures using the same ipsilateral radial artery, respectively. Primary radial failure occurred in 5.8% for second attempt and 13% for a third attempt, whereas crossovers were noted in 2.7% and 2.6%, respectively. Main reasons for failed re-access of ipsilateral radial artery were related either to operators reluctance to repeat attempt (primary failure) or to issues with puncture site (crossover). In a high-volume TRA center, patients who required repeat catheterization within 24 hours and within the first 30 days had the same radial artery re-accessed in the majority of cases.

Room-temperature fiber laser at 3.92 μm

Rare-earth-doped fiber lasers are promising contenders in the development of spectroscopy, free-space communications and countermeasure applications in the 3 - 5 {\mu}m spectral region. However, given the limited transparency of the commonly used fluorozirconate glass fiber, these systems have only achieved wavelength coverage up to 3.8 {\mu}m, hence fueling the development of more suitable fiber glass compositions. To this extent, we propose in this Letter a novel heavily holmium-doped fluoroindate fiber, providing extended transparency up to 5 {\mu}m, to demonstrate the longest wavelength room temperature fiber laser at 3.92 {\mu}m. Achieving

Transradial experience with bioresorbable vascular scaffolds: A case-matched study with metallic drug-eluting stents

\approx

Transcatheter Aortic Valve Implantation in Patients With Paradoxical Low-Flow, Low-Gradient Aortic Stenosis

200 mW of output power when cladding pumped by a commercial 888 nm laser diode, this demonstration paves the way for powerful mid-infrared fiber lasers emitting at and beyond 4 {\mu}m.

3.4 W monolithic erbium-doped all-fiber laser at 3.55 μm

BACKGROUND Whether polymeric bioresorbable vascular scaffolds (BVS) implantation with transradial approach is feasible and safe is unknown. We compared the feasibility and safety of the transradial approach for BVS delivery with metallic drug-eluting stents (DES). METHODS We identified 118 consecutive patients who underwent BVS implantation and we compared 30-days and 1-year results with 118 matched patients with DES. Patients were matched for age, sex, risk factors and clinical indication. RESULTS Rates of transradial approach were 98% in the BVS group vs 95% in the DES group (P = 0.16) with 5Fr used in 38% and 32% (P = 0.34), respectively. The number of stents was similar in both groups, 2.6 ± 1.5 vs 2.4 ± 1.3 (P = 0.23). Although maximal pressure for stent deployment was identical in both groups (16 ± 3 atm), more lesions were pre-dilated (83% vs 52%, P < 0.001) and post-dilated (71% vs 33%, P < 0.001) in the BVS group. Contrast volume (217 ± 97 vs 175 ± 108 ml, P < 0.001), fluoroscopy time (16 [10-23] vs 13 [8-21] min, P = 0.04) and procedure duration (65 ± 31 vs 56 ± 47 min, P = 0.045) were significantly higher in the BVS group. Major adverse cardiac events, including death, myocardial infarction and target vessel revascularization remained similar in both groups, 1.7% vs 0.8% (P = 0.56) at 30 days and 10% vs 8.5% (P = 0.66) at 1 year. At 1 year, stent thrombosis occurred in 2 (1.7%) patients in the BVS group and 1 (0.8%) patient in the DES group (P = 0.56). CONCLUSION The use of transradial approach for BVS compared to DES implantation was feasible and safe in all-comers, although BVS implantation included more technical challenges. Outcomes up to 1-year remained comparable in both groups.

High efficiency cascade fiber laser at 2.8 μm

Controversial data exist on clinical outcomes of patients with paradoxical low-flow, low-gradient aortic stenosis (PLF-LG-AS) undergoing valve replacement. The objective of this study was to determine the clinical outcomes and treatment futility in patients with paradoxical low-flow (PLF), low-gradient (LG) severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI). A total of 493 patients with severe symptomatic AS and preserved ejection fraction (>50%) undergoing TAVI were included. Patients were divided in two groups: high gradient AS group (HG-AS; mean gradient ≥40 mm Hg and stroke volume index >35 ml/m2, n = 396); and PLF, LG AS group (PLF-LG-AS; mean AV gradient <40 mm Hg and indexed stroke volume ≤35 ml/m2, n = 97). The primary endpoint was treatment futility defined as death or poor functional status (New York Heart Association class III and/or IV) at 6-month follow-up. There were no differences in mortality between groups (PLF-LG-AS: 5%, HG: 8%; adjusted odds ratio (OR): 0.85, 95% confidence interval (CI):0.29 to 2.46), but PLF-LG-AS patients remained more frequently in New York Heart Association class III to IV (20% vs 8% in the HG group, adjusted OR: 2.46, 95% CI:1.19 to 5.07). TAVI treatment futility was more frequent in the PLF-LG-AS group (24% vs 14%, adjusted OR: 1.90 [1.01 to 3.57]), and patients with PLF-LG-AS exhibited a higher rate of rehospitalization for cardiovascular causes (9% vs 5%, adjusted OR: 2.95, 95% CI:1.08 to 8.09). Previous myocardial infarction and chronic obstructive pulmonary disease were associated with treatment futility (p< 0.03 for both). In conclusion, TAVI was a futile treatment in one fourth of patients with PLF-LG-AS. These results underscore the complexity and need for improving the clinical decision-making process and management of patients with PLF-LG-AS.

Recent development in mid-infrared fluoride glass fiber lasers

Mid-infrared fiber lasers operating around 3.5 μm find applications in various fields such as remote sensing, polymer processing and spectroscopy. Recent demonstrations based on the ⁴F<inf>9/2</inf> → ⁴I<inf>9/2</inf> transition in Er³⁺:ZrF<inf>4</inf> fibers have shown effective laser emission up to 1.52 W [1] by relying on a dual-wavelength pumping (DWP) scheme. This novel approach mitigates the low Stokes efficiency associated with single-wavelength pumping and reduces ion bottlenecking in lower lying energy states. Here, we report the first monolithic DWP erbium doped all-fiber laser bounded by two fiber Bragg gratings (FBGs) emitting ∼ 3.4 W at 3.55 μm with a total optical efficiency of 22 %. To the best of our knowledge, these results represent the highest output power and efficiency ever achieved at this wavelength in a rare-earth doped fiber laser.

Diode-pumped mid-infrared fiber laser with 50% slope efficiency

Diode-pumped erbium-doped fluoride glass (Er:FG) fiber lasers operating near the water absorption peak have a potential use in medical [1] and spectroscopy [2] applications. However, their efficiency is generally limited to the maximum Stokes efficiency limit of ∼35%. Until now, the only way demonstrated to exceed this limit takes advantage of an energy transfer upconversion process (ETU). Nonetheless, such ETU processes are only efficient in heavily doped fibers which lead to high heat load per unit length of the fiber, thus limiting the power scaling potential of such an approach. To date, the highest slope efficiency of 35.4%, slightly exceeding the Stokes limit, was reported through ETU with a 7 mol. % Er3+:FG fiber laser emitting near 2.8 μm [3].