Long-term survival after xenograft versus homograft aortic root replacement: Results from a prospective randomized trial.

OBJECTIVE: The study objective was to investigate the long-term survival of patients undergoing xenograft versus homograft full root aortic valve replacement. METHODS: A total of 166 patients requiring aortic valve surgery were randomized to undergo the Freestyle (Medtronic Inc, Minneapolis, Minn) bioprosthesis (N = 90) or a homograft (N = 76) full root aortic valve replacement between 1997 and 2005 in a single institution. Six patients randomly assigned to the homograft crossed over to the Freestyle bioprosthesis because of the unavailability of suitably sized homografts. All surgeons were required to adhere to the standard surgical technique for homograft root implantation previously described. Follow-up was 98.5% complete. RESULTS: The mean age of the study population was 65 ± 8 years. Coronary artery bypass grafting was associated with root aortic valve replacement in 76 of 166 patients (46%, P = not significant between groups), and overall hospital mortality was 4.8% (8/166, P = not significant between groups). Median follow-up was 13.8 years (range, 0-21.8 years; 2033 patient-years). The Kaplan-Meier survival analysis showed that there was no significant difference in overall survival between the 2 arms at 5, 10, and 15 years. Twenty-year survival was 28.3% ± 5% for the Freestyle group versus 25.1% ± 5.7% for the homograft group (P = .90), which was comparable to the age- and sex-matched UK general population. The freedom from aortic valve reoperation at 20 years was comparable for the Freestyle group versus the homograft group (67.9% ± 8.8% vs 67.2% ± 10.3%, respectively; P = .74). CONCLUSIONS: This is the first study to investigate the long-term survival of xenograft versus homograft full root aortic valve replacement from a prospective randomized trial. The observed 20-year overall survival and freedom from aortic valve reoperation serve as a benchmark for future studies on interventions for aortic valve disease in the elderly.

Colorimetry characterization of molecular reorientation transition in thin nematic cells.

The characterization of equilibria and their transition is fundamental in dynamic systems. Experimentally, the characterization of transitions is complex due to time scales separation, the effect of thermal fluctuations, and inherent experimental imperfections. Liquid crystal devices are derived from the manipulation of the molecular reorientation and transition between them by employing external electrical and magnetic fields. Here, we investigate and determine the Fréedericksz transition using hue measurements of the transmitted light in thin nematic liquid crystal cells. Based on birefringent retardation experienced by transmitted light due to molecular reorientation, the color adjustment of the nematic liquid crystal cells under white light illumination is characterized. By monitoring the hue of the transmitted light, the bifurcation diagram is determined. As a function of the voltage frequency, the critical transition voltage is characterized. The critical voltage increases with the applied frequency.

Limitations in ionization-induced compression of femtosecond laser pulses due to spatio-temporal couplings.

It was recently proposed that ionization-induced self-compression could be used as an effective method to further compress femtosecond laser pulses propagating freely in a gas jet [He et al., Phys. Rev. Lett. 113, 263904 2014]. Here, we address the question of the homogeneity of the self-compression process and show experimentally that homogeneous self-compression down to 12fs can be obtained by finding the appropriate focusing geometry for the laser pulse. Simulations are used to reproduce the experimental results and give insight into the self-compression process and its limitations. Simulations suggest that the ionization process induces spatio-temporal couplings which lengthen the pulse duration at focus, possibly making this method ineffective for increasing the laser peak intensity.

Right internal mammary artery versus radial artery as second arterial conduit in coronary artery bypass grafting: a case-control study of 1526 patients.

OBJECTIVE: Additional arterial grafts such as the right internal mammary artery (RIMA) or the radial artery (RA) have been proposed to improve long term outcomes in coronary artery bypass grafting (CABG). RA is largely preferred over RIMA as it is less technically demanding and there is a perception that bilateral IMA usage increases the risk of sternal wound complications. However, there is a paucity of direct comparison of the two conduits to guide surgeons to choose the best second arterial conduit for CABG. METHODS: A propensity score adjusted analysis of patients undergoing multiple arterial grafting with RIMA (n = 747) and RA (n = 779) during the study period (2001-2013) was conducted to investigate the impact of the two strategies on early and late outcomes. RESULTS: RIMA did not increase the incidence of postoperative complications including deep sternal wound infection (P = 0.8). Compared to the RIMA, the RA was associated with an increased risk for late mortality (Hazard Ratio [HR] 1.9; 95% confidence interval (CI) 1.2-3.1; P = 0.008) and repeat revascularization (HR 1.5; 95% CI 1.0-2.2; P = 0.044). A trend towards an extra risk for late mortality from RA over RIMA was observed among diabetic (HR 3.3; 95% CI 1.1-9.7) and obese patients (HR 2.1; 95% CI 0.8-5.46). CONCLUSIONS: RIMA as a second conduit did not increase the operative risk including sternal wound complications and improved long term outcomes including overall survival when compared to RA. This advantage was stronger among diabetic and obese patients. These findings strongly support RIMA as the first choice second arterial conduit in CABG. Further randomized studies with angiographic control and long-term follow-up are needed to address this issue.

Grism compressor for carrier-envelope phase-stable millijoule-energy chirped pulse amplifier lasers featuring bulk material stretcher.

We demonstrate compression of amplified carrier-envelope phase (CEP)-stable laser pulses using paired transmission gratings and high-index prisms, or grisms, with chromatic dispersion matching that of a bulk material pulse stretcher. Grisms enable the use of larger bulk stretching factors and thereby higher energy pulses with lower B-integral in a compact amplifier design suitable for long-term CEP control.

Predictors of survival after gastrointestinal complications in bypass grafting.

Between April 2001 and December 2005, data were collected prospectively from 2,320 consecutive patients who underwent first-time coronary artery bypass. Logistic multiple regression analyses were carried out to determine the independent predictors of gastrointestinal complications and death. There were 65 major gastrointestinal complications identified in 65 (2.8%) patients: paralytic ileus in 15, mesenteric ischemia in 12, upper gastrointestinal hemorrhage in 16, lower gastrointestinal hemorrhage in 8, small bowel obstruction in 5, pseudoobstruction in 5, and others in 4. The 30-day mortality was 21.5% (14 patients). Female sex, preoperative creatinine >200 µmol·L(-1), previous gastrointestinal pathology, low cardiac output, readmission to the intensive care unit, postoperative pulmonary complications, arrhythmias, hemofiltration, and reoperation were independent predictors of major gastrointestinal complications. Independent risk factors for death were readmission to the intensive care unit, the need for hemofiltration, reoperation, and ischemic bowel. Careful hemodynamic control and optimization of perioperative organ perfusion are important to minimize the mortality associated with major gastrointestinal complications after coronary artery bypass.

Nonlinear optical transformation of the polarization state of circularly polarized light with holographic-cut cubic crystals.

Nonlinear modification of circularly polarized light propagating in holographic-cut cubic crystals is theoretically predicted and experimentally observed. To the best of our knowledge this is the first demonstration of nonlinear modification of circularly polarized light with cubic crystals.

Efficient cross polarized wave generation for compact, energy-scalable, ultrashort laser sources.

The generation of high contrast and ultrashort laser pulses via a compact and energy-scalable cross polarized wave filter is presented. The setup incorporates a waveguide spatial filter into a single crystal XPW configuration, enabling high energy and high intensity transmission, efficient contrast enhancement and pulse shortening at the multi-mJ level. Excellent XPW conversion of up to 33% (global efficiency: 20%, intensity transmission: 40%) led to an output energy of 650 µJ for an input of 3.3 mJ. Additionally, efficient conversion under specific input phase conditions, allowed pulse shortening from 25 fs to 9.6 fs, indicating the prospective application of this setup as a high energy, ultrabroad laser source.

Closed-loop carrier-envelope phase stabilization with an acousto-optic programmable dispersive filter.

We demonstrate arbitrary carrier-envelope (CE) phase control of femtosecond laser pulses by an acousto-optic programmable dispersive filter (AOPDF), with an accuracy better than pi/100 at a repetition rate of 1 kHz. We also demonstrate, for the first time to the best of our knowledge, 15 Hz closed-loop CE phase stabilization using an AOPDF inside a 1 kHz chirped pulse amplifier to correct for slow CE phase drifts.

Ruptured sinus of Valsalva aneurysm presenting as ST-elevation myocardial infarction.

BACKGROUND: A 52-year-old man presented with central chest pain, which he had experienced for 8 h. He had no other associated symptoms and no prior history of cardiovascular disease. INVESTIGATIONS: Electrocardiography, chest radiography, coronary angiography, aortic angiography, echocardiography, CT thorax with contrast. DIAGNOSIS: Ruptured aneurysm of the sinus of Valsalva. MANAGEMENT: Emergency sternotomy and pericardiotomy, followed by aortic root replacement.

Full-scale experimentations on alternative materials in roads: analysis of study practices.

In France beginning in the 1990s, the topic of road construction using various alternative materials has given rise to several studies aimed at clarifying the technical and environmental feasibility of such an option. Although crucial to understanding and forecasting their behaviour in the field, an analysis of feedback from onsite experiences (back analysis) of roads built with alternative materials has not yet been carried out. The aim of the CAREX project (2003-2005) has been to fill this gap at the national scale. Based on a stress-response approach applied to both the alternative material and the road structure and including the description of external factors, a dedicated standardised framework for field data classification and analysis was adopted. To carry out this analysis, a set of 17 documented field experiments was identified through a specific national survey. It appears that a great heterogeneity exists in data processing procedures among studies. The description of material is acceptable while it is generally poor regarding external factors and structure responses. Structure monitoring is usually brief and mechanical loads too weak, which limits the significance of field testing. For future full-scale experiments, strengthening the realism within the testing conditions would be appropriate.

A framework of analysis for field experiments with alternative materials in road construction.

In France, a wide variety of alternative materials is produced or exists in the form of stockpiles built up over time. Such materials are distributed over various regions of the territory depending on local industrial development and urbanisation trends. The use of alternative materials at a national scale implies sharing local knowledge and experience. Building a national database on alternative materials for road construction is useful in gathering and sharing information. An analysis of feedback from onsite experiences (back analysis) is essential to improve knowledge on alternative material use in road construction. Back analysis of field studies has to be conducted in accordance with a single common framework. This could enable drawing comparisons between alternative materials and between road applications. A framework for the identification and classification of data used in back analyses is proposed. Since the road structure is an open system, this framework has been based on a stress-response approach at both the material and structural levels and includes a description of external factors applying during the road service life. The proposal has been shaped from a review of the essential characteristics of road materials and structures, as well as from the state of knowledge specific to alternative material characterisation.

Does perioperative administration of thyroid hormones improve outcome following coronary artery bypass grafting?

The question addressed in this review is whether supplementation with thyroid hormones during the perioperative period improves the outcome of patients undergoing coronary artery bypass surgery. Altogether 88 relevant papers were identified using the below mentioned search, seven papers represented the best evidence to answer the question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses were tabulated. We conclude that although widespread interest has been shown on the use of thyroid hormones in the perioperative period, and the effect of cardiopulmonary bypass on thyroid hormone metabolism widely studied, there is no substantial evidence to justify routine use of thyroid hormones in patients undergoing coronary artery bypass grafting.

Propensity score analysis of early and late outcome after redo off-pump and on-pump coronary artery bypass grafting.

BACKGROUND: The purpose of this study was to compare early and late results of redo-CABG with (redo-ONCAB) and without (redo-OPCAB) cardiopulmonary bypass. METHODS: From April 2001 to September 2006 redo-CABG was performed in 110 patients (redo-ONCAB=50 and redo-OPCAB=60). Applying the propensity score, 43 OPCAB patients were matched with 43 ONCAB patients. The mean EuroScore was 5+/-4.7 and 5+/-3.4 for redo-ONCAB and redo-OPCAB, respectively (p=0.5). The number of diseased coronary arteries was 3+/-0.5 and 2+/-0.8 in redo-ONCAB and redo-OPCAB, respectively (p<0.01). RESULTS: Twelve patients underwent OPCAB through anterior thoracotomy while the rest of the patients (n=74) underwent median sternotomy. Mean number of grafts performed was 3+/-0.8 in redo-ONCAB and 2+/-0.6 in redo-OPCAB (p<0.05). The need for postoperative insertion of intra-aortic balloon pump (IABP) was higher (p=0.02) in redo-ONCAB (n=9, 21%) than redo-OPCAB (n=1, 2%). The duration of postoperative ventilation was 55+/-98.7 h for redo-ONCAB and 10+/-12.8h for redo-OPCAB (p=0.008). No differences were found in the incidence of other postoperative complications. The 30-day mortality rate was 6.9% for redo-ONCAB (n=3) and 2.3% redo-OPCAB (n=1; p=NS). Mean follow-up for redo-ONCAB was 30+/-21.3 months (range 0.1-63 months) and that of redo-OPCAB was 37+/-19.2 months (0.1-62.5 months). Actuarial survival at 5 years was 87+/-5.5% for redo-ONCAB and 95+/-3.2% for redo-OPCAB (p=0.17). Event-free survival was 71+/-8.0% for redo-ONCAB and 78+/-7.2% for redo-OPCAB (p=0.32). CONCLUSION: OPCAB is an acceptable strategy in selected patients requiring redo-CABG. Employing a strategy of OPCAB for those patients with 2 or fewer lesions and ONCAB for those with more diffuse disease, redo-OPCAB and redo-ONCAB have similar early and late outcomes.

Nonlinear mirror based on cross-polarized wave generation.

We present a new type of nonlinear mirror based on the generation of a cross-polarized wave through a nonresonant electronic third-order process. It is characterized by a reflection coefficient that depends on the input intensity. Its behavior results from the interference between the nonlinearly generated cross-polarized wave and a pi/2 phase-retarded wave. This setup has a lot of advantages: it does not require any phase matching, it is achromatic and suitable for femtosecond pulses, linear losses are easily adjustable, and the overall behavior is predictable. The device has been experimentally tested using BaF2 and YVO4 crystals.

Comment on "Generation of 10(11) contrast 50 TW laser pulses".

We argue for a different physical interpretation of the results given in the recent Letter by Chvykov et al. [Opt. Lett.31, 1456 (2006)] in which a double nonlinear crystal scheme for cross-polarized wave generation is analyzed. We discuss the most important factors that explain the origin of the two-crystal scheme's increased efficiency, namely, the Kerr lensing effect and a Gouy phase shift. The position and orientation of the second crystal relative to the first one are unambiguously defined; related effects are illustrated by already published works on the subject.

Non-anastomotic avulsion of a left internal mammary artery graft--a rare complication of minimally invasive direct coronary artery bypass surgery.

OBJECTIVE: To describe a rare complication of minimally invasive coronary artery bypass surgery. METHOD: Case report. RESULTS: We present a 72-year-old patient with a left anterior descending artery stenosis who underwent elective minimally invasive direct coronary artery bypass (MIDCAB) surgery. Three months post-operatively he developed an anterior chest wall haematoma with electrocardiographic and enzyme evidence of myocardial ischaemia, though without haemodynamic embarrassment. Surgical exploration revealed non-anastomotic avulsion of the LIMA graft, which was bleeding freely into the left hemithorax. CONCLUSIONS: Minimally invasive direct coronary artery bypass surgery is now widely practised. Post-operative interruption of the left internal mammary artery graft is uncommon and avulsion of the graft proximal to the anastomosis with the left anterior descending artery has only been described in the literature on three occasions. This complication has been reported once in the setting of conventional bypass surgery and twice in the setting of minimally invasive direct coronary artery bypass surgery. In all of these cases, abrupt graft failure resulted in significant haemodynamic and/or ischaemic compromise, and all occurred within two weeks of surgery. Clinicians should be reminded of this rare though potentially catastrophic complication of MIDCAB surgery.

A two crystal arrangement to fight efficiency saturation in cross-polarized wave generation.

We describe a method that overcomes the observed saturation effect in cross polarized wave (XPW) generation. The previously reported internal efficiencies for XPW generation are known to be limited to around 15% whatever the length of the nonlinear medium and/or the input intensity values are. At the opposite, the theoretical limit had been estimated to be close to 25%. Here we show that using two thin BaF(2) crystals separated at optimum distance the saturation level of XPW generation efficiency can be drastically increased. An internal efficiency of 30% is demonstrated experimentally using two BaF(2) crystals.