The final touch in the delivery of a fixed prosthesis.
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Cementation↗
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Application of a low-adhesive color-developing chewing gum system to patients with osseointegrated implant-supported prostheses.
Few methods have been described that can quantitatively evaluate masticatory function. This study investigated the usefulness of a low-adhesive color-developing chewing gum system for the evaluation of patients with implant-supported prostheses. Fifteen dentate subjects and 22 patients with dental implants participated in this study. The color developed in the gum after chewing reflects masticatory function and is evaluated quantitatively with a color-analyzing system. The results indicate that this system can be used to evaluate occlusal function, and they confirm the importance of stable prostheses for higher masticatory function.
Adult↗
In vitro pulsatile flow evaluation of a stentless porcine aortic bioprosthesis.
Suboptimal hemodynamic performance, tissue calcification, and limitation in long-term durability have been encountered clinically after aortic valve replacement with currently available bioprostheses. It is believed that some of these problems may be caused, directly or indirectly, by the stents of the bioprostheses. To address these deficiencies, the authors undertook the development of the Edwards Prima Stentless Bioprosthesis. This study was designed to evaluate the hemodynamic performance of the Edwards Prima Stentless Bioprosthesis in a pulse duplicator system. The stented Carpentier-Edwards Porcine Bioprosthesis (Baxter Healthcare Corp., Irvine, CA), which has been used in United States clinics for more than 10 years, was used as a control device. The flow fields in the vicinity of the test bioprostheses were inspected with color Doppler flow mapping. The transvalvular pressure gradients were measured invasively with a catheter and calculated with the Doppler determined velocity using a simplified Bernoulli equation. Additionally, the leakage volumes were determined with an electromagnetic flowmeter. In the Doppler flow mapping study, during systole, a central flow was observed distal to the stentless and stented bioprostheses. The central flow distal to the stentless bioprosthesis was broader than that observed distal to its stented counterpart. During diastole, no regurgitation was detected by color Doppler flow mapping in either the stentless or stented groups. The Doppler determined transvalvular pressure gradients correlated well with those measured by catheter (r = 0.990). Moreover, it was learned that the transvalvular pressure gradients of the stentless bioprosthesis were less than those of its stented counterpart, especially for the smaller sizes.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Evaluation of cryopreserved arteries as alternative small vessel prostheses.
Biologic or synthetic grafts have had limited success in small vessel applications. Studies were initiated to assess the potential use of cryopreserved (CP) arteries as coronary artery bypass conduits. Sheep carotid arteries (internal diameter: 4 mm; length: 10 cm) were cryopreserved in a nutrient media containing 10% DMSO and were stored in a nitrogen vapor at -150 degrees C. After thawing, histological, enzyme-histochemical and functional studies showed slight histological alterations, preservation of enzymal activities and an abolition of the contractile response. In a sheep model, arterial substitution of a 10 cm segment of carotid artery was realised by implantation of fresh autografts ( n = 4); fresh allografts (n = 9) and CP allografts (n = 9). After 3 months, all autografts were patent with slight histological alterations. Fresh and CP allografts showed similar modifications: patency rate was 7/9 in both groups. Intimal thickening with cell proliferation was seen in fresh (3/7) and CP (4/8) arteries; loss of smooth muscle medial cells was constant. Adventitia was always involved by a marked inflammatory reaction. One characteristic of CP allografts was the frequent presence of large dystrophic calcifications. In conclusion, morphologic and functional arterial changes occurred after freezing and thawing. In spite of vascular rejection, the patency rate of allografts after 3 months of implantation in arterial circulation remained high and does not seem influenced by cryopreservation.
Animals↗
Functional results after aortic valve repair in aortic root ectasia.
BACKGROUND AND AIMS OF THE STUDY: Aortic insufficiency due to dilation of the aortic root is a common finding. Although combined replacement of the aortic valve and the ascending aorta is regarded as standard treatment, total replacement of the proximal aorta with a tube graft and resuspension of the valve is a new alternative. METHODS: Between June 1993 and June 1995, 23 patients underwent this type of aortic repair. Seven patients exhibited the typical features of Marfan's syndrome. Echocardiography was performed pre- and intraoperatively as well as three, six and then every 12 months postoperatively for a cumulative follow up period of 355 months (5-30; mean 15.9 +/- 7.9 months). RESULTS: The pre-existing aortic valve insufficiency (grade II-IV, mean 2.9) was reduced postoperatively to grade 0-1 (mean 0.3). The NYHA functional class improved from a mean of 2.8 to 1.8. During the follow up period 20 patients showed a stable valve function with either no (n = 13), or a mild valve regurgitation (n = 7). Two patients had to be reoperated for progressive aortic insufficiency 11 and 14 months after repair, undergoing valve replacement. A third patient required reoperation because of relapsing endocarditis. CONCLUSION: It is concluded that in patients with aortic valve insufficiency due to dilation of the proximal aorta, valve sparing reconstruction is a promising approach. Without the need for anticoagulation, good functional results could be demonstrated. Further follow up is required to assess the long term function of this kind of aortic valve repair.
Aorta↗
Variability of regurgitation in Björk-Shiley mitral valves and relationship to disc occluder design: an in vitro two-dimensional color-Doppler flow mapping study.
BACKGROUND AND AIMS OF THE STUDY: Normal prosthetic valves have regurgitation that varies according to valve type and design. The Björk-Shiley prosthetic mitral valve is a tilting disc valve that has undergone design changes since its introduction. From 1969 to 1981, Delrin, was used to make the disc occluder. After 1971, the occluder was made from Pyrolite (i.e. Conical and Radiopaque-Spherical valves). Our aim was to quantify the regurgitation of Delrin and Radiopaque-Spherical Björk-Shiley prosthetic mitral valves with color-Doppler flow mapping in an in vitro model that simulates transesophageal echocardiography imaging. MATERIALS AND METHODS: Normal unimplanted Björk-Shiley Delrin (BSD), Björk-Shiley Radiopaque-Spherical (BSS) and explanted (17 +/- 3 yrs) BSD valves (25, 27, and 29 mm) were studied in a pulse duplication system. The regurgitant leakage volume of the valves was measured with an electromagnetic flow probe at flow rates of 3.0, 5.0, and 7.0 L/min, a pulse rate of 70 beats/min, and a mean systemic pressure of 100 mmHg. Color-Doppler flow mapping was performed with a 3.7 MHz transducer positioned on the atrial chamber at an image depth of eight centimeters. The maximal regurgitant jet areas were measured offline and averaged from three beats. RESULTS: Maximal jet area, measured with color-Doppler flow mapping, correlated with regurgitant leakage volume (r = 0.82). Normal unimplanted and explanted BSD valves had greater regurgitant leakage volumes and jet areas than BSS valves for all sizes and flow rates studied. Regurgitant jet areas of normal unimplanted and explanted BSD valves were similar. CONCLUSION: Knowledge of the type of Björk-Shiley valve is important in the clinical evaluation of regurgitation severity by transesophageal echocardiography. The echocardiographic appearance of regurgitation of BSD valves does not necessarily imply valve dysfunction.
Blood Flow Velocity↗
Evaluation of abdominal aortic aneurysm after endoluminal treatment: comparison of color Doppler sonography with biphasic helical CT.
OBJECTIVE: The purpose of this study is to compare color Doppler sonography with biphasic helical CT in the evaluation of abdominal aortic aneurysms after endovascular repair. MATERIALS AND METHODS: Fifty-five patients prospectively underwent both color Doppler sonography and helical CT within 7 days after treatment by endovascular stent-graft. Aneurysmal thrombosis, the patency of the grafts, and the presence of a leak were evaluated in all patients. When a perigraft leak was observed, an attempt was made to identify its origin and outflow vessels. Helical CT was considered the gold standard technique. RESULTS: Helical CT revealed aneurysmal thrombosis in 33 patients and a perigraft leak in 22 patients. In five patients, helical CT detected a small perigraft leak not shown by color Doppler sonography. In three patients with suboptimal examinations, color Doppler sonography revealed a suspected perigraft leak that was not confirmed by helical CT. In these eight patients, the perigraft leak was sealed or no longer observed during follow-up. Compared with enhanced helical CT, the sensitivity and specificity of color Doppler sonography for the diagnosis of a perigraft leak were 77% and 90%, respectively. In seven other patients, helical CT was superior to color Doppler sonography in detecting the origin of the perigraft leak and the outflow vessels. Two iliac artery dissections and one distal migration of the prosthesis were revealed only by helical CT. CONCLUSION: Although color Doppler sonography may detect substantial perigraft leaks, helical CT is superior for detecting the origin of the perigraft leak, the outflow vessels, and the detection of complications related to the procedure.
Aged↗
An improved nipple prosthesis.
A nipple-areola reconstruction of prosthesis completes the process of breast reconstruction. Reconstructions are technically difficult and have poor long-term results, whereas commercial nipple prostheses are unsatisfactory in matching the normal colour and shape. We describe a simple technique for the manufacture of a custom made nipple-areola prosthesis.
Color↗
Achieving an esthetic appearance with a fixed prosthesis by submucosal grafts.
A review of a new plastic surgical procedure using autogenous grafts of dense connective tissue placed submucosally in anterior areas of collapsed, deformed edentulous ridges has been presented. This technique allows augmentation of an anterior, deformed edentulous ridge to a proper form, color, and texture before placement of a fixed prosthesis. Previous solutions to this problem have resulted in an esthetic compromise at best. Long-term follow-up shows good dimensional stability offering an acceptable solution to a difficult prosthetic problem.
Alveolar Ridge Augmentation↗
Light-weight RTV silicone for maxillofacial prostheses.
Weight is a problem in retention of large skin-textured maxillofacial prostheses. The purpose of this investigation was to test the feasibility of mixing foam RTV silicone rubber with conventional RTV silicone rubber to obtain a light-weight material. Various mixtures of foam and conventional silicone rubber were formulated and tested for strength, accuracy of molding, color application, color stability, and texture. A special flask to support the mold was necessary in order to overcome expansion problems associated with gas formation of the foam silicone rubber. The mold required venting to release the gas and to reduce the expansion of the prosthesis in order to maintain accuracy. Molding, accuracy, texture, and color problems were overcome. Reduction of weight proportionate to reduction of tear strength of the material formulated, however, did not allow routine use of mixtures of foam and conventional silicone. When the weight of a prosthesis is critical and excessive and thickness is sufficient to give adequate strength, the foam and conventional silicone mixture can be used.
Color↗
A procedure for design of a posterior resin-bonded prosthesis.
A procedure is described that uses red and brown crayon-type pencils and graphite pencil lead with a surveyor to draw a color-coded design on a study cast before fabrication of a posterior resin-bonded prosthesis. During diagnosis and treatment planning, abutments on the study cast are analyzed for undercuts and the height of contour on each abutment tooth is marked with a graphite pencil lead. Metal retainers for the prosthesis are indicated with brown lines drawn on the abutments. Enamel surfaces requiring alteration to allow insertion of the prosthesis and provide resistance to displacement are marked in red on the study cast. The surveyed color-coded study cast can be used as a reference guide by both the clinician and the laboratory technician during fabrication of the posterior resin-bonded prosthesis.
Bicuspid↗
Evaluation of color changes of silicone maxillofacial materials after exposure to sunlight.
A number of authors have listed the following qualities as ideal for maxillofacial material: (1) original physical and mechanical properties comparable to the human tissue that they are replacing, (2) the ability to sustain these properties during service, (3) compatibility with human tissues and the adhesives used to adhere the prostheses to tissue, and (4) the quality of being easy to process and an insensitivity to processing variables. Clinical experience has indicated that there is frequent and for the replacement of maxillofacial appliances because of rapid discoloration in the service environment and/or degradation of the physical and dynamic properties of the base elastomer. Color stability in the service environment may be the most important factor in patient acceptance of the prosthesis. The results of this study suggested that aging rather than exposure to sunlight results in most of the color changes observed in the HTV and RTV base polymers studied.
Color↗
Intractable hemolysis caused by perivalvular leakage following mitral valve replacement with St. Jude Medical prosthesis.
Nine patients with intractable hemolysis caused by perivalvular leakage following mitral valve replacement with a St. Jude Medical prosthesis are presented. All patients had dark-colored hemoglobinuria, which appeared from 1 day to 44 days after the operation, with moderate or severe hepatorenal insufficiency. One patient died of multiorgan failure. The other 8 patients underwent reoperation, and all survived. Reoperation revealed that all leakages were tiny and had no adverse effect on hemodynamics. In all the patients having reoperation, hemoglobinuria disappeared immediately after the procedure. Surface-scanning electron microscopy of the sewing cuff of the St. Jude Medical prosthesis revealed the rough surface structure of the sewing ring. Because of this irregular, shaggy surface structure, greater shearing forces against erythrocytes can be generated when there is perivalvular leakage.
Adolescent↗
Color Doppler diagnosis of mechanical prosthetic mitral regurgitation: usefulness of the flow convergence region proximal to the regurgitant orifice.
In prosthetic or paravalvular prosthetic mitral regurgitation, transthoracic color Doppler flow mapping can sometimes fail to detect the regurgitant jet within the left atrium because of the shadowing by the prosthetic valve. To overcome this limitation, we assessed the utility of color Doppler visualization of the flow convergence region (FCR) proximal to the regurgitant orifice in 20 consecutive patients with mechanical prosthetic mitral regurgitation documented by surgery and cardiac catheterization (13 of 20 patients). In addition, we studied 33 patients with normally functioning mitral prostheses. Doppler studies were performed in the apical, subcostal, and parasternal long-axis views. An FCR was detected in 95% (19 of 20) of patients with prosthetic mitral regurgitation. A jet area in the left atrium was detected in 60% (12 of 20) of patients. In 18 of 19 patients with Doppler-detected FCR, the site of the leak was correctly identified by observing the location of the FCR. A trivial jet area was detected in eight patients with a normally functioning mitral prosthesis; in none was an FCR identified. Thus color Doppler visualization of the FCR proximal to the regurgitant orifice is superior to the jet area in the diagnosis of mechanical prosthetic mitral regurgitation. Moreover, FCR permits localization of the site of the leak with good accuracy.
Adult↗
Colour doppler valvar and subvalvar flow diameter imaging versus echo score in mitral stenosis: comparison with type of surgery.
OBJECTIVE: To compare the value of echo score with that of Doppler subvalvar flow broadening in deciding the type of mitral stenosis surgery. PATIENTS: 30 patients, mean age 47 years, with severe stenosis undergoing surgery were divided into two groups according to type of surgery: open heart commissurotomy (group 1, n = 12), or prosthesis (group 2, n = 18). A control group of 10 patients with prosthesis served as reference, representing mild stenosis without subvalvar connection. METHODS: For echo, the score proposed by Wilkins for cross sectional imaging was used. For Doppler, the flow diameters were measured in cm by an independent examiner from the long axis view in early diastole at two levels: (1) at the level of the stenosis (origin flow diameter), and (2) 1.5 cm downstream from the stenosis in the left ventricle (subvalvar flow diameter) with calculation of a Doppler ratio relating these two measurements, expressed as a percentage of broadening. Diagnostic value was compared for both procedures. RESULTS: There was no significant difference in age, mitral valve areas, or haemodynamics for the two groups. Mean values (SD) were: echo score: group 1, 9.83 (1.26) v group 2, 10.8 (8.1), NS; Doppler ratio %: group 1, 44 (24) v group 2, 12 (21) (P < 0.001); control group: 69 (15). The per cent diagnostic value for an open heart commissurotomy of respective cut off points was: Doppler ratio > 25% (range 71% to 87%); echo score < 10 (range 50% to 75%). CONCLUSIONS: The new Doppler ratio diagnostic value agreed better with surgical management, repair or prosthesis, in this study. Thus, it appears to better reflect the subvalvar involvement and changes in kinetics than the echo score alone. This easy Doppler method might become a routine examination for follow up of patients with open heart commissurotomy, to avoid performing repeated transoesophageal echocardiography.
Adolescent↗
Evaluation of aortic insufficiency by Doppler color flow mapping.
The color Doppler echocardiographic studies and aortic angiograms of all patients who had these procedures performed within 2 weeks of each other between October 1984 and August 1985 were reviewed to determine whether any parameters of the regurgitant jet visualized by color Doppler study predicted the severity of aortic insufficiency as assessed by angiographic grading. Patients with an aortic valve prosthesis were excluded. Twenty-nine patients had aortic insufficiency and had adequate color Doppler studies for analysis. The mean time between color Doppler examination and angiography was 2.3 days (range 0 to 12). The maximal length and area of the regurgitant jet were poorly predictive of the angiographic grade of aortic insufficiency. The short-axis area of the regurgitant jet from the parasternal short-axis view at the level of the high left ventricular outflow tract relative to the short-axis area of the left ventricular outflow tract at the same location best predicted angiographic grade, correctly classifying 23 of 24 patients. However, the jet could be seen from this view in only 24 of the 29 patients. The height of the regurgitant jet relative to left ventricular outflow tract height measured from the parasternal long-axis view just beneath the aortic valve correctly classified 23 of the 29 patients. Mitral stenosis or valve prosthesis, which was present in 10 patients, did not interfere with the diagnosis or quantitation of aortic insufficiency by these methods.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Pseudoaneurysm of the left ventricle after mitral valve replacement. Diagnosis 6 years after the intervention].
We present a case of left ventricular pseudoaneurysm diagnosed by chance 6 years after a second surgical intervention on the mitral valve (replacement with a St. Jude prosthesis). A combination of cross sectional and color-Doppler studies led to the correct diagnosis. A transesophageal echocardiographic investigation did not provide further information, while the diagnosis was confirmed by computed tomography with contrast agent. A retrospective analysis of previous examinations revealed that the pseudoaneurysm developed shortly after the mitral valve replacement, remaining stable over the years. The patient was clinically asymptomatic, the size of the pseudoaneurysm did not increase during a 2 years followup, and we decided to follow a conservative treatment.
Aged↗
Left ventricular outflow obstruction resulting from insertion of mitral prostheses leaving the native leaflets intact: adverse clinical outcome in seven patients.
Left ventricular (LV) outflow obstruction may result from retaining the anterior mitral leaflet when a mitral prosthesis is inserted in the mitral anulus. We retrospectively reviewed the echocardiograms (two-dimensional Doppler and Doppler color flow imaging, or transesophageal with color flow imaging) obtained in seven patients with preoperative mitral regurgitation who had a prosthesis implanted with the native mitral leaflets left intact. Systolic anterior motion of the native anterior mitral leaflet, as seen in dynamic LV outflow tract obstruction, was observed in six of seven patients. LV fractional shortening preoperatively was less than or equal to 0.25 in all (mean 0.20 +/- 0.04) and did not significantly (p = ns) increase postoperatively (mean 0.27 +/- 0.12). Color flow imaging revealed disturbed systolic flow in the LV outflow tract in five patients, and all had systolic anterior motion of the native anterior mitral leaflet. Continuous wave Doppler detected significant systolic LV outflow tract jets in five patients averaging 4.1 +/- 0.9 m/sec. Mitral prosthetic function was normal (pressure half-time of 81 +/- 25 msec and mean gradient of 7 +/- 3 mm Hg +/- SD) in five patients. Clinical follow-up revealed that all had died, six of them within 2 months of their operation. Thus systolic anterior motion of the native anterior mitral leaflet occurs commonly after prosthetic mitral valve insertion with the native leaflets left intact. Continuous wave Doppler often demonstrates increased systolic LV outflow tract velocities consistent with dynamic LV outflow obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗