[Esthetic problems in prosthetic restoration of the face in relation to the surrounding structures].
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Color↗
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How should we describe forward flow through replacement mitral valves using echocardiography?
Pressure half-time is no longer thought to reflect orifice area in normally-functioning mitral valves, but no satisfactory alternative method has been validated. Effective orifice area by the continuity equation is theoretically justified. However, we have shown no correlation against manufacturer's area in a clinical study of 40 bileaflet mechanical valves. Valve resistance is useful in native mitral stenosis, but virtually no work exists for replacement valves. We have shown no correlation against manufacturer's area in the same 40 mechanical valves. The proximal isovelocity surface area method based on the continuity equation can only be applied using the transesophageal approach; it is therefore not practical. Imaging and colour flow provide good qualitative or semiquantitative information, and together with continuous wave Doppler allow detection of obstruction for clinical diagnosis. An adequate quantitative method for research use has not yet been established.
Algorithms↗
[Study of hydrodynamic characteristics of artificial heart valves by photochromic imaging].
The paper deals with the hydrodynamics of artificial heart valves (AHVs) used in clinical practice. It reviews and analyzes the studies of AHV hydrodynamics, as well as the hydrodynamic beds which stimulate physiological flow through the valve. Photochronic imaging (PCI) is proposed for examination of AHV hydrodynamic characteristics under model physiological flow. The hydrodynamics of different AHVs was tested on the beds simulating blood flow through AHVs by employing PCI. PCI involved preparation of model photochronic solution that simulates blood, colour labels by using laser radiation. In the model photochronic solution, 10(-6)-10(-9)-sec laser radiation gave rise to linear colour labels whose movement was recorded by a speed camera in the flow behind the valve. The profiles of speed behind the valves, the dimensions of congestive areas, the positions of flow detachment and regurgitation flow were calculated by a speed shooting in different periods of valvular performance. PCI defined congestive areas behind the valves, the areas of closed circulations, the sizes of reversing flow areas and examined the time course of flow behind the valves as a whole. The paper is of interest for AHV designers and cardiac surgeons who apply various AHVs.
Color↗
Vital tooth esthetics in Captek restorations.
Captek crowns and bridges employ optical effects that simulate vital tooth esthetics. The intensive red color of the blood in the vital pulp plays an important role in natural tooth appearance. This role is often ignored in restoration construction and results in a dead-looking restored tooth. To achieve optimal tooth esthetics, it is essential to mimic these often overlooked esthetic qualities.
Ceramics↗
Regarding: "The incidence and natural history of type I and II endoleak: a 5-year follow-up assessment with color duplex ultrasound scan".
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Aortic Aneurysm, Abdominal↗
Endothelialization of biosynthetic vascular prostheses after laser perforation.
OBJECTIVE: This study was undertaken to investigate the feasibility of transmural capillary ingrowth into the inner surface of biosynthetic vascular prostheses (Omniflow, BioNova, Melbourne, Australia) through perforations created by an excimer laser, thus inducing an endothelial cell coverage. METHOD: Biosynthetic vascular prostheses (Omniflow, 10 cm length, 6 mm diameter) were perforated with an excimer laser (diameter of the holes 50 to 100 microm, distance 4 mm) and implanted into the carotid arteries of eight sheep. They were compared to untreated Omniflow prostheses implanted at the contralateral side. Three months after implantation the prostheses were explanted and evaluated by gross morphology, histologic examination, scanning electron microscopy, and immunohistochemical staining for factor VIII to identify endothelial cells. RESULTS: All grafts remained patent. Gross morphologic examination revealed no significant difference in the thrombus-free surface between perforated and untreated prostheses. However, scanning electron microscopy showed endothelial cells in the midgraft portion of all perforated prostheses, whereas collagen fibers, fibrin meshwork, and activated platelets formed the inner layer in six of eight untreated Omniflow prostheses. Transmural capillary ingrowth in the laser group was verified by positive factor VIII staining for endothelial cells in the laser channels. CONCLUSION: Spontaneous endothelialization of biosynthetic vascular prostheses can be achieved by transmural capillary ingrowth through perforations in the wall of the prostheses in an experimental sheep model.
Anastomosis, Surgical↗
The morphology of the proximal femur. A three-dimensional radiographic analysis.
Biological fixation of cementless femoral implants requires primary stability by optimal fit in the proximal femur. The anatomy of the bone must then be known precisely. We analysed in vitro the accuracy of bone measurements of 32 femurs and compared the dimensions obtained from radiographs and CT scans with the true anatomical dimensions. Standard radiographs gave only a rough approximation of femoral geometry (mean difference: 2.4 +/- 1.4 mm) insufficiently accurate to allow selection of the best fitting prosthesis from a range of sizes and altogether inadequate to design a custom-made prosthesis. CT scans give greater accuracy (mean difference: 0.8 +/- 0.7 mm) in our experimental conditions, but in clinical practice additional sources of error exist.
Aged↗
Change in character of mitral prosthesis regurgitant murmur with bundle-branch block: correlation of auscultatory and echocardiographic findings.
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Aged↗
New aspects in the histological examination of polyethylene wear particles in failed total joint replacements.
The most important long-term complication in total joint replacements is aseptic osteolysis. Wear particles such as polyethylene (PE) debris are considered to be one of the causes that play a central role. Several studies indicated that PE can be visualised in paraffin-embedded tissue sections not only by polarised light, but also after oil red staining. To determine whether oil red staining enables sensitive detection of PE, we examined staining of mechanically-produced PE particles by oil red. Furthermore, we studied oil red staining of paraffin-embedded tissue specimens of patients with failed uncemented and cemented total knee and hip prostheses. We applied double labelling of sections by immunohistochemistry using the macrophage marker anti-CD68 and oil red staining. We found that oil red stains both isolated PE particles and PE particles in paraffin-embedded tissue sections. Polymethylmethacrylate particles in failed cemented arthroplasties did not stain in paraffin sections. Double labelling showed strong colocalisation of CD68 and PE. We suggest that oil red staining is a sensitive method to detect PE particles. Oil red staining is particularly helpful in these cases which show a characteristic histological feature of aseptic prosthesis loosening without particles being detectable with routine microscopy and polarised light. We also established that immunohistochemical methods can be applied together with the oil red staining method.
Antigens, CD↗
Preparation and characterization of collagen-elastin matrices from blood vessels intended as small diameter vascular grafts.
This study describes the selective removal of cell and cell residues from small and large diameter blood vessels for the preparation of tubular collagen:elastin matrices intended for small diameter vascular prosthesis. The results showed that total or partially devitalized collagen:elastin matrices may be conveniently prepared without denaturation of the collagen:elastin matrix with a high degree of preservation of the proteins. The efficiency of cell removal and the extent collagen and elastic fiber preservation were dependent on the segment and the type of blood vessel under study, with arteries characterized by a higher susceptibility of cell removal and better preservation of the collagen-elastin matrix.
Alkalies↗
Serial Doppler echocardiographic evaluation of small-sized sorin bicarbon prostheses.
OBJECTIVE: The Sorin Bicarbon prosthesis (Sorin Biomedica, Saluggia, Italy) is a bileaflet valve with curved-profile leaflets, a rolling hinge mechanism, and a pyrolytic carbon-coated titanium alloy housing and sewing ring. Although the Sorin Bicarbon prosthesis has been implanted in greater than 80,000 patients, and reference values on the hemodynamic performance of valve prostheses are needed to avoid patient-prosthesis mismatch, few Doppler echocardiographic data are available on the prosthesis in the aortic position. The aim of this study is to provide a detailed echocardiographic evaluation of the hemodynamic performance and regression of left ventricular hypertrophy after aortic valve replacement with the Sorin Bicarbon prosthesis. METHODS: The study included 182 patients who received a 21-mm (n = 61) or 23-mm (n = 121) Sorin Bicarbon prosthesis for pure or prevalent aortic stenosis who underwent serial echocardiograms at 3, 6, and 12 months after aortic valve replacement. RESULTS: Mean and peak gradients significantly decreased (P <.001) during follow-up to values of 12 +/- 3 and 22 +/- 6 mm Hg for the 21-mm prosthesis and values of 11 +/- 4 and 19 +/- 6 mm Hg for the 23-mm prosthesis at 1 year. Left ventricular mass index showed a 17% decrease to 120 +/- 27 g/m(2) in recipients of the 21-mm prosthesis (P <.001) and a 21% decrease to 123 +/- 29 g/m(2) in recipients of the 23-mm prosthesis (P <.001). A larger prosthesis size was the only predictor of a higher left ventricular mass index regression. Among recipients of the 21-mm prosthesis, body surface area of greater than 1.85 m(2) was associated with a lower regression of left ventricular mass index. The effective orifice area index was 1.00 +/- 0.11 and 1.08 +/- 0.14 cm(2)/m(2) in recipients of the 21-mm and 23-mm prostheses, respectively. CONCLUSIONS: Size 21 mm and 23 mm Sorin Bicarbon prostheses show low transprosthetic gradients, with significant reduction of left ventricular mass index during the first postoperative year. The reported effective orifice areas might be useful for aortic valve replacement in patients with a small aortic annulus to avoid patient-prosthesis mismatch.
Aged↗
The anastomosis angle does change the flow fields at vascular end-to-side anastomoses in vivo.
PURPOSE: The purpose of this article was to study the influence of the anastomosis angle on the flow fields at end-to-side anastomoses in vivo. METHODS: Polyurethane grafts of similar internal diameter to that of the abdominal aorta (8 mm) were implanted from the suprarenal to the infrarenal level in 10 pigs. Three angles of standardized distal end-to-side anastomoses (90 degrees, 45 degrees, and 15 degrees) were studied. The anatomic position of the anastomoses was constant, the proximal outflow segment was occluded, and the flow rate through the graft was controlled. Flow visualization was accomplished by a color-flow Doppler ultrasound system. RESULTS: The angulation was reproduced within 10%. Gross hemodynamic parameters were stable, and the similarity parameters were typical for peripheral bypasses (mean Reynold's number is 424 and Womersley's parameter is 5.9). The flow fields were clearly dependent on the anastomosis angle. A zone of recirculation (approximately 5% of the flow area), extending from the toe to one diameter downstream, was found in the 45-degree and 90-degree anastomoses. No flow disturbances were detected at the toe and one diameter downstream with an anastomosis angle of 15 degrees. At the heel different recirculating flow patterns were found in the different anastomoses. CONCLUSION: The anastomosis angle does change the flow fields at vascular end-to-side anastomoses in vivo.
Anastomosis, Surgical↗
Assessment of severity of mechanical prosthetic mitral regurgitation by transoesophageal echocardiography.
OBJECTIVE: To evaluate the ability of colour Doppler transoesophageal echocardiography (TOE) to assess quantitatively prosthetic mitral valve insufficiency. METHODS: 47 patients were studied with multiplane TOE and cardiac catheterisation. Proximal jet diameter was measured as the largest diameter of the vena contracta. Regurgitant area was measured by planimetry of the largest turbulent jet during systole. Flow convergence zone was considered to be present when a localised area of increased systolic velocities was apparent on the left ventricular side of the valve prosthesis. Pulmonary vein flow velocity was measured at peak systole and diastole. RESULTS: Mean (SD) proximal jet diameter was 0.63 (0.16) cm, with good correlation with angiographic grades (r = 0.83). Mean (SD) maximum colour jet area was 7.9 (2.5) cm2 (r = 0.69) with worse correlation if a single imaging plane was used for measurements (r = 0.62). The ratio of systolic to diastolic peak pulmonary flow velocity averaged 0.7 (1.3) cm (r = -0.66) with better correlation (r = -0.71) if patients with atrial fibrillation were excluded. Mean (SD) regurgitant flow rate was 168 (135) ml/s and regurgitant orifice area was 0.56 (0.43) cm2, with good correlation with angiography (r = 0.77 and r = 0.78, respectively). CONCLUSIONS: TOE correctly identified angiographically severe prosthetic mitral regurgitation, mainly by the assessment of the flow convergence region and the proximal diameter of the regurgitant jet.
Adult↗
A facial prosthesis made of porcelain fused to metal: a clinical report.
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Chromium Alloys↗
Coarctation of the aorta in neonates and young infants: surgical experience.
A retrospective analysis of repair of aortic coarctation in young infants was conducted. Between April 1997 and December 2000, 21 patients under 4 months of age underwent repair of coarctation. Their mean age and weight were 41 42 days (range, 2 to 120 days) and 3.6 0.7 kg (range, 2.6 to 4.9 kg). The indications for surgery were congestive heart failure and/or shock. Diagnosis was made by 2-dimensional echocardiography with Doppler color flow imaging. Preoperative gradients ranged from 25 to 100 mm Hg. Aortic arch hypoplasia was present in 8 patients; 7 patients also had ventricular septal defect. Wide excision of the coarctation segment with extended end-to-end anastomosis was performed in 20 patients, while 1 required a Gore-Tex interposition graft between the left common carotid artery and the descending aorta. Subclavian angioplasty was performed to augment the anastomosis in 1 patient. There was no early mortality. One patient died 2 months after surgery. Follow-up examination revealed recoarctation in 5 patients (23.8%), all of whom underwent successful balloon dilatation. In conclusion, wider excision of the coarctation with extended end-to-end anastomosis reduces the chances of recoarctation. Percutaneous balloon angioplasty for treating recoarctation is effective in immediately reducing pressure gradients.
Age Factors↗
Twelve-year follow up with the Sorin Pericarbon bioprosthesis in the mitral position.
BACKGROUND AND AIMS OF THE STUDY: The aim of this study was to evaluate the long-term follow up of the Pericarbon pericardial bioprosthesis implanted in the mitral position. METHODS: Between January 1985 and January 1991, 78 patients (26 males, 52 females; mean age 56.9 +/- 7.8 years) underwent isolated mitral valve replacement with a Pericarbon valve. All bioprostheses were size 29 mm and implanted by the same surgeon. RESULTS: Total follow up was 663.2 pt-years and it was 97% complete. Early mortality was 1.3% (1/78); two minor cerebral embolisms were observed as early complications. At 12 years the overall survival rate was 85.0 +/- and valve-related survival 93.1 +/- 3.0%; freedom from embolic events was 83.0 +/- 4.5% and from endocarditis 98.7 +/- 1.3%. Freedom from primary tissue failure was 56.8 +/- 6.6%; it was 86.3 +/- 7.5% in patients aged > 60 years and 36.8 +/- 8.2% in younger patients. There were 27 reoperations, 26 for primary tissue failure, one for endocarditis. Comparison between basal and follow up echocardiographic studies showed a significant stenotic deterioration of the bioprosthesis and a negligible incidence of regurgitation. Morphological findings of explanted bioprostheses were characterized by stenotic and diffuse microcalcification, but no tissue tear was observed. CONCLUSIONS: These results confirm that the Pericarbon bioprosthesis is structurally safe and free from the fatigue problems which afflicted the first and second generation of pericardial valves. As with other tissue valves, the rate of calcification is age-dependent, suggesting preferential use of the Pericarbon prosthesis in elderly people.
Bioprosthesis↗
Neuropsychologic outcome after open-heart surgery.
A neuropsychologic (NP) study was carried out on 49 patients who had had cardiac valvular replacement to investigate the determinants of postoperative outcome. The results were assessed together with operative data and with neurologic and quantitative EEG (QEEG) findings. Of the operative variables, perfusion time and unexpected intraoperative events were the most important factors leading to postoperative NP impairment. Clinical neurologic outcome correlated positively with NP changes. Differences between various cardiologic and age groups were found in the postoperative NP findings. Changes in frequency in QEEG reflected the NP changes more reliably than did amplitude. Significantly one of the tests, a modification of the Stroop color test, was found to be prognostically important, suggesting that it might be possible to construct test batteries of value in predicting high operative risk. The results show that multiparameter investigation using NP testing together with clinical and QEEG follow-up is useful in the assessment of cerebral disorders attributable to open-heart surgery.
Adolescent↗
Closure of prosthetic paravalvular mitral regurgitation with the Gianturco-Grifka vascular occlusion device.
Paravalvular regurgitation associated with prothetic mitral valves is often a consequence of infectious endocarditis. The condition is usually treated with debridement and repeat surgical valve replacement. However, repeated operations are associated with high risk. This report describes a case of successful transcatheter treatment of severe paravalvular mitral regurgitation and pulmonary edema in a patient in whom repeat mitral valve replacement was not believed possible.
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