A novel approach to the development of Distributed Temperature-Sensing (DTS) systems based on Raman Scattering in Multimode optical fibers operating at around 800 nm is presented, focusing on applications requiring temperature profile measurement in the range of a few hundreds of meters. In contrast to the standard Raman DTS systems, which aim to shorten the pulse space width as much as possible to improve the precision of measurement, the novel approach studied in this work is based on the use of pulses with a space width that is approximately equal to the distance covered by the fiber under test. The proposed technique relies on numerical post-processing to obtain the temperature profile measurement with a precision of about ±3 °C and a spatial resolution of 8 m, due to the transaction phases of the optical pulses.
View Article and Find Full Text PDFA low-cost polymer-based structure is proposed to improve the coupling between a fiber end section and photodetector active surface in optical links based on standard single-mode fiber (SSMF), which employs vertical cavity surface emitting lasers operating at 850 nm, i.e., below the SSMF cutoff wavelength.
View Article and Find Full Text PDFDirect modulation of a laser source is often utilized in realizing optical fiber connections where the cost of the entire system must be kept at a low level. An undesired consequence of this choice is the onset of the laser frequency chirp effect, which is detrimental in the case of either digital or analog links, and must be evaluated with precision in order to perform an accurate design of the whole system. Various methods of evaluation of the chirp parameters have been proposed, and the choice among them is typically made on the basis of the laboratory equipment available at the moment.
View Article and Find Full Text PDFAn important effect of the frequency chirp of the optical transmitter in radio over multimode fiber links is put into evidence experimentally and modeled theoretically for the first time, to our knowledge. This effect can have an important impact in short-range connections, where, although intermodal dispersion does not generally cause unacceptable limitations to the transmittable bandwidth, the presence of modal noise must be accurately kept under control, since it determines undesired real-time fluctuations of the link.
View Article and Find Full Text PDFWe demonstrate a highly tunable deep notch filter realized in a liquid-crystal photonic-bandgap (LCPBG) fiber. The filter is realized without inducing a long-period grating in the fiber but simply by filling a solid-core photonic-crystal fiber with a liquid crystal and exploiting avoided crossings within the bandgap of the LCPBG fiber. The filter is demonstrated experimentally and investigated using numerical simulations.
View Article and Find Full Text PDFBackground: The aim of this study was to evaluate the appropriateness of prescription of non-invasive cardiological tests (exercise stress test, echocardiography, Holter monitoring and vascular echography), consecutively performed in our outpatient laboratory during 4 weeks.
Methods: We collected the following data: the appropriateness of prescription (according to the Italian Federation of Cardiology guidelines); test indications; the prescribing physician (cardiologist/non-cardiologist); type of prescription (elective/urgent); clinical utility (useful/useless) and result (normal/abnormal) of each test.
Results: We evaluated 960 prescriptions (320 exercise tests; 282 echocardiograms; 158 Holter tests; 200 vascular echographies).
Anthracyclines represent an established therapy for various hemopoietic and solid tumors; however the cardiotoxicity of these agents continues to limit their therapeutic potential in many cancer patients. Acute life-threatening cardiac toxicity which occurs immediately after a single dose of therapy is very rare under current treatment protocols. This form of toxicity occurs unexpectedly owing to a large variation in individual sensitivity.
View Article and Find Full Text PDFBackground: Mass screening for occult abdominal aortic aneurysm is not realistic for the low prevalence of this condition in the general population. Screening in a high-risk population, especially during standard echocardiographic examination, could be more cost-effective than a separate screening program. The aim of this study was to evaluate the feasibility and accuracy of a rapid evaluation (examination arbitrary time-limit of 2 min) of the abdominal aorta at the end of a routine transthoracic echocardiographic examination.
View Article and Find Full Text PDFBackground: AF is one of the most common complications after CABG. The aim of the study was to identify the risk factors for postoperative AF.
Methods: Between June and December 2000, 129 consecutive patients (72 men, 47 women; mean age 67 +/- 6 years) underwent preoperative signal-averaged electrocardiogram (SAECG) with assessment of filtered P-wave duration (fPWD) and of the root mean square voltage of the last 10 and 20 ms of atrial depolarization (RMSV10 and RMSV20, respectively) before CABG.
Background: We evaluated the appropriateness of the prescription of echocardiography, exercise testing, Holter monitoring and vascular sonography for ambulatory patients, performed during 4 weeks in 21 outpatient laboratories in Tuscany and Umbria, Italy.
Methods: We collected the following data: the appropriateness of the prescription (according to the guidelines of the Italian Federation of Cardiology), the prescribing physician (cardiologist vs noncardiologist), the synthetic result (normal vs abnormal) and the clinical utility (useful vs useless) of each exam.
Results: We evaluated 5614 prescriptions (patients: 3027 males, 2587 females; mean age 63 years, range 14-96 years).
Heparin-induced thrombocytopenia (HIT) is a possible complication of heparin administration consequent to an immunological reaction. It usually resolves without clinical sequelae with discontinuation of the drug. However, sometimes it causes severe platelet activation with thrombosis.
View Article and Find Full Text PDFBackground: Exercise-induced ST-segment elevation in Q-wave leads has been traditionally associated with passive stretching of the infarct wall, perinecrotic ischemia and, according to recent scintigraphic studies, with myocardial viability. At present, however, no definitive conclusions are available. We evaluated the potential role of a time-domain analysis of exercise-induced ST-segment elevation for the identification of viable myocardium and residual ischemia in patients with previous Q-wave myocardial infarction.
View Article and Find Full Text PDFBackground And Aim Of The Study: Mitral valve repair (MVR) is the treatment of choice in patients with degenerative valve disease. However, controversy persists as to whether mitral valve annuloplasty should always be included as part of the reconstructive procedure.
Methods: The records of 62 consecutive patients undergoing MVR for degenerative disease between January 1994 and December 1996 were reviewed.
Ann Thorac Surg
January 2000
Background: Aortic valve replacement in elderly patients with a small aortic annulus may pose difficult problems in terms of prosthesis selection. We have evaluated the hemodynamic performance of the 21-mm Carpentier-Edwards Perimount bioprosthesis implanted in elderly patients.
Methods: From July 1996 to June 1998, 19 patients (17 women and 2 men, mean age 76+/-4 years and mean body surface area 1.
Ann Thorac Surg
December 1999
Background: The Edwards Prima stentless valve (EPSV) is a porcine aortic root cylinder with resected coronary ostia, fixed in glutaraldehyde at low pressure. The purpose of this study was to evaluate the hemodynamic performance of the EPSV 1 year after aortic valve replacement.
Methods: From December 1994 to February 1996, 29 patients underwent aortic valve replacement with EPSV used in the subcoronary position (group 1, n = 23) or as a root replacement (group 2, n = 6).
J Heart Valve Dis
September 1999
Background And Aim Of The Study: Small-sized prostheses may be associated with high transprosthetic gradients, particularly in patients with a body surface area (BSA) >1.70m2, affecting left ventricular mass regression, symptom improvement and long-term survival. However, the influence of such gradients on exercise tolerance has not been clearly defined.
View Article and Find Full Text PDFJ Cardiovasc Surg (Torino)
April 1999
A 29-year-old female was found to have a left ventricular mass while in the 14th week of gestation. Seven years earlier she had undergone removal of a left ventricular myxoma. At re-operation, after elective interruption of pregnancy, a recurrent left ventricular myxoma was successfully excised.
View Article and Find Full Text PDFThe use of bilateral internal mammary artery (BIMA) grafting for myocardial revascularization has been demonstrated to provide long-term benefits compared to revascularization using single left internal mammary artery (SIMA) and venous conduits. However, it is still controversial whether the use of BIMA is associated with a higher hospital mortality and morbidity. The present study retrospectively evaluated the possible advantages related to the use of BIMA at 3-year follow-up and whether the presence of operative risk factors in patients with BIMA could limit the application of the procedure in myocardial revascularization.
View Article and Find Full Text PDFA quadricuspid aortic valve was observed in a patient requiring aortic valve replacement because of severe aortic regurgitation, while in another it was accidentally detected by means of transesophageal echocardiography performed during coronary artery bypass grafting. This report discusses the apparent rarity of this malformation and stresses the need for periodical controls in patients known to have a quadricuspid aortic valve.
View Article and Find Full Text PDFJ Heart Valve Dis
September 1998
Quadricuspid aortic valve is an uncommon cause of aortic regurgitation. We report two patients who underwent aortic valve replacement because of severe aortic incompetence; the presence of a quadricuspid aortic valve was an accidental surgical finding. In one patient the aortic valve comprised two equal-sized larger cusps and two equal-sized smaller cusps, while in the other it comprised three cusps of similar size and a small accessory cusp between the right and non-coronary cusps.
View Article and Find Full Text PDFBackground And Aims Of The Study: Aortic valve replacement in patients with a small aortic annulus may represent a surgical challenge. We have evaluated a simplified technique to enlarge the aortic annulus which consists of extending the aortotomy incision to divide the commissure between the left and non-coronary cusps into the interleaflet triangle without opening the left atrium.
Methods: This technique was used in 16 patients (15 women, one man; mean age 66 +/- 9 years) who underwent aortic valve replacement between August 1994 and February 1996.
In order to identify the risk factors which could predict outcome after coronary artery bypass grafting in patients with left ventricular dysfunction, 80 consecutive patients with an ejection fraction < or = 30%, who underwent isolated coronary artery bypass grafting at the authors' centre between January 1994 and May 1996 were evaluated. Preoperatively, mean(s.d.
View Article and Find Full Text PDFBackground: Transmyocardial laser revascularization (TMLR), a surgical technique designed to improve perfusion in the ischemic myocardium by creating transmural channels, has been performed thus far using a carbon dioxide laser, with apparently gratifying early results. We have investigated clinically TMLR using a holmium laser as sole therapy for patients with coronary artery disease that is not amenable to traditional treatment such as coronary artery bypass grafting or percutaneous transluminal coronary angioplasty.
Methods: From November 1995 to December 1996, 16 patients underwent TMLR using a holmium laser.
Background And Aims Of The Study: The surgical management of patients with aortic valve disease associated with ascending aortic dilatation is a controversial issue. Structural abnormalities of the aortic wall predispose to further aortic enlargement and possibly to ascending aortic dissection (AAD). Indications to concomitant replacement of aortic valve and ascending aorta have not yet been clearly defined.
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