Effectiveness of single detachable COOK coils in closure of the patent ductus arteriosus.
(25/188)
OBJECTIVE: To assess the efficacy and safety of single detachable coils in the closure of PDAs. METHODS: Review of cases in which a single detachable coil was implanted. The diameter of the ampulla was used to select coil size. Diameters of the PDA, ampulla and residual shunts were measured. RESULTS: There were 36 patients with a mean minimal ductal diameter of 2.2 +/- 0.6 mm. Immediately after implantation, 46% of the patients had residual shunts and after 24 hours, only 28%. A final spontaneous closure rate of 94% was observed after 21 months. There was a significant (p < 0.01) difference when minimal PDA diameter of those who had complete closure within 24 hours (median: 2 mm, interquartile range: 1.7-2.3 mm) was compared to those with a residual shunt (median: 2.5 mm, interquartile range: 2.3-3.2 mm). Negligible complications were experienced. CONCLUSIONS: Single Cook detachable coils are effective for PDA closure with a low complication rate if properly selected. There is a high rate of spontaneous closure of trivial residual shunts. In patients with a minimal ductal diameter > or = 2 mm and a residual shunt, more coils may be considered. (+info)
The impact of hydrogel lens settling on the thickness of the tears and contact lens.
(26/188)
PURPOSE: To investigate the effect of contact lens insertion on the thickness on the prelens tear film (PLTF), the contact lens, and the postlens tear film (PoLTF). METHODS: Twelve contact lens wearers (mean age, 32.7 years; four males) inserted etafilcon A hydrogel lenses (power: -2.00 D, base curve: 8.3 mm) in both eyes immediately before testing. Previously described interference techniques, based on oscillations in reflectance spectra, were used to measure the thickness of the PLTF, contact lens, and PoLTF. The thickness of the layers is derived from the frequency of the oscillations. Spectra were captured 1 minute after lens insertion and every minute thereafter for 30 minutes. Least squares regression fits were used to determine the relation between thickness of each layer and time. RESULTS: The combined data from all subjects for PLTF thickness were fit with an exponential decay plus a constant thickness; the initial thickness was 4.5 micrometers, the time constant was 7.1 minutes (P < 0.001), and final thickness was 2.5 micrometers. The apparent thickness of the contact lens declined linearly at an average rate of 0.051 micrometers/minute (P < 0.001). The PoLTF thickness remained constant at 2.5 micrometers (P = 0.46). CONCLUSIONS: For most subjects, the PLTF thinned significantly over the course of the first 30 minutes of lens wear. The apparent thinning of the contact lens may be caused by a real thinning of the lens, but also may have a contribution from improved centration over the 30-minute period. The PoLTF remained relatively stable during this period. (+info)
Prosthetic alignment and sizing in computer-assisted total knee arthroplasty.
(27/188)
We implanted 60 posterior stabilized total knee prostheses (P.F.C. Sigma, DePuy, Warsaw, USA). In 30 cases, we used a CT-free navigation system (Vector Vision, Brain LAB, Heimstetten, Germany), and in 30 matched-paired controls, we used a conventional manual implantation. We compared postoperative long-leg radiographs in the two groups. The results revealed a significant difference in favor of navigation. In addition, we compared the preoperative anteroposterior dimension of the femoral condyle with the postoperative value. While there were no significant differences in the preoperative anteroposterior dimension of the femoral condyle between the two groups, the postoperative value in the navigation group was significantly larger than that of the preoperative value. Therefore, surgeons using navigation systems should guard against the possibility of oversizing when determining the size of the femoral component. (+info)
Impact of valve prosthesis-patient mismatch on pulmonary arterial pressure after mitral valve replacement.
(28/188)
OBJECTIVES: We sought to determine the impact of valve prosthesis-patient mismatch (PPM) on pulmonary arterial (PA) pressure after mitral valve replacement (MVR). BACKGROUND: Pulmonary arterial hypertension is a serious complication of mitral valve disease, and it is a major risk factor for poor outcome after MVR. We hypothesized that valve PPM might be a determinant of PA hypertension after MVR. METHODS: Systolic PA pressure was measured by Doppler echocardiography in 56 patients with normally functioning mitral prosthetic valves. Mitral valve effective orifice area (EOA) was determined by the continuity equation and indexed for body surface area. RESULTS: Thirty patients (54%) had PA hypertension defined as systolic PA pressure >40 mm Hg, whereas 40 patients (71%) had PPM defined as an indexed EOA < or =1.2 cm(2)/m(2). There was a significant correlation (r = 0.64) between systolic PA pressure and indexed EOA. The average systolic PA pressure and prevalence of PA hypertension were 34 +/- 8 mm Hg and 19% in patients with no PPM versus 46 +/- 8 mm Hg and 68% in patients with PPM (p < 0.001). In multivariate analysis, the indexed EOA was by far the strongest predictor of systolic PA pressure. CONCLUSIONS: Persistent PA hypertension is frequent after MVR and strongly associated with the presence of PPM. The clinical implications of these findings are important given that PPM can largely be avoided by using a simple prospective strategy at the time of operation. (+info)
Consistency and accuracy of measurement of lower-limb amputee anthropometrics.
(29/188)
Lower-limb amputees often exhibit large fluctuation in residual-limb shape, necessitating careful observation and anthropometric measurement for prosthetists to ensure socket fit. Anthropometric measurement may become more important as an outcome measure indicating success in rehabilitation. This study investigated the accuracy and reliability of seven prosthetic anthropometric measurement devices as used by a group of eight prosthetic-orthotic practitioners and a group of five prosthetic-orthotic students to measure six common anthropometric dimensions on three foam positive models of transtibial amputee residual limbs. Two of the models were identical, enabling assessment of individual repeatability. Some clinically significant errors were noted in the results; however, the general variability in measurements was not clinically significant. Students were slightly more consistent than practitioners; students were more consistent with linear measurements, while practitioners were more consistent with circumferential measures. The results further demonstrated that the VAPC measurement device used in the study was both inaccurate and unreliable. (+info)
A preliminary investigation into the development of 3-D printing of prosthetic sockets.
(30/188)
The socket is considered an element of major importance in the makeup of a prosthesis. Each socket is a tailor-made device, designed to fit the unique geometry of the patient's residual limb. The design and manufacture of a prosthetic socket traditionally has been a manual process that relies on the use of plaster of Paris casts to capture the shape of the patient's residual limb and then artisan fabrication techniques to manufacture the socket. Computer-aided design and manufacturing technologies have overcome some of the shortcomings of the traditional process, but the final manufacture of the prosthetic socket is still performed manually. Rapid prototyping (RP), a relatively new class of manufacturing technologies, creates physical models directly from three-dimensional (3-D) computer data. Previous research into the application of RP systems to the manufacture of prosthetic sockets has focused on expensive, high-end technologies that have proven too expensive. This paper investigates the use of a cheaper, low-end RP technology known as 3-D printing. Our investigation was an initial approach to using a technology that is normally associated with producing prototypes quickly, some of which could not be manufactured by alternative means. Under normal circumstances, these printed components are weak and relatively fragile. However, comfortable prosthetic sockets manufactured with 3-D printing have been used in preliminary fittings with patients. (+info)
Prosthesis-patient mismatch: definition, clinical impact, and prevention.
(31/188)
Prosthesis-patient mismatch (PPM) is present when the effective orifice area of the inserted prosthetic valve is too small in relation to body size. Its main haemodynamic consequence is to generate higher than expected gradients through normally functioning prosthetic valves. This review updates the present knowledge about the impact of PPM on clinical outcomes. PPM is common (20-70% of aortic valve replacements) and has been shown to be associated with worse haemodynamic function, less regression of left ventricular hypertrophy, more cardiac events, and lower survival. Moreover, as opposed to most other risk factors, PPM can largely be prevented by using a prospective strategy at the time of operation. (+info)
Contact lenses and special back surface design after penetrating keratoplasty to improve contact lens fit and visual outcome.
(32/188)
AIMS: To describe the fitting of patients with high or irregular astigmatism following penetrating keratoplasty with contact lenses and to answer the question whether or not contact lenses with special back surface design can improve visual acuity in complex cases after penetrating keratoplasty. METHODS: 28 eyes were included. They were fitted with contact lenses with a special back surface that was designed for optical rehabilitation after penetrating keratoplasty. Four different types of these lenses (tricurve, keratoconus, reverse, oblong) were used selectively depending on abnormal eccentricity determined by videokeratoscope. The patients were followed up for an average period of 15.5 months. Lens tolerance and corrected visual acuity were evaluated and compared with that corrected with spectacles. RESULTS: The visual acuity was significantly improved in nearly all eyes with an average increase of 3.6 lines (maximal nine lines) accompanied by good contact lens tolerance and satisfactory contact lens fit. No noticeable complications were observed. CONCLUSION: Contact lenses with special back surface design can improve visual results and lens tolerance, and minimise problems in contact lens fitting. This is in favour of contact lenses as an alternative to surgical procedures for correction of high or irregular astigmatism after penetrating keratoplasty. This procedure is recommended especially in cases of patients who decline further operative interventions. (+info)