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At least 559 records · Page 31Linked to original sources
PubMed2000

Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention.

Prosthesis-patient mismatch is present when the effective orifice area of the inserted prosthetic valve is less than that of a normal human valve. This is a frequent problem in patients undergoing aortic valve replacement, and its main hemodynamic consequence is the generation of high transvalvular gradients through normally functioning prosthetic valves. The purposes of this report are to present an update on the concept of aortic prosthesis-patient mismatch and to review the present knowledge with regard to its impact on hemodynamic status, functional capacity, morbidity and mortality. Also, we propose a simple approach for the prevention and clinical management of this phenomenon because it can be largely avoided if certain simple factors are taken into consideration before the operation.

Aortic Valve Stenosis↗
PubMed2006

[Clinical study of implant-retained facial prosthesis].

OBJECTIVE: To evaluate clinical results and technical characteristics of implant-retained facial prosthesis. METHODS: Six patients with facial defects underwent implant retained prosthesis treatment, of which 3 orbita defects (including upper and lower eyelids, eyeball) in 3 cases, 2 ears defects in 2 cases, and a nose defect in one case. Under local anaesthesia 21 extra-oral implant were placed, facial prosthesis were individually made six month postoperatively. Follow up ranged from 6 month to 6 years. RESULTS: All 21 implants osseointegrated well, implant lost and peri implantitis was not found. All 6 cases had individual facial prosthesis and were satisfied with the prosthesis. CONCLUSIONS: Extra oral implants provided excellent retainment for facial prosthesis; result of current silicon with individual color shade is encouragable.

Dental Prosthesis, Implant-Supported↗
PubMedDate not supplied

[An iliac-mesenteric-atrial shunt in the Budd-Chiari syndrome with extensive thrombosis of the inferior vena cava].

A 34-year-old woman with no history of any liver diseases was admitted to the service for a Budd-Chiari syndrome and an extensive thrombosis of the inferior vena cava. The symptoms of the portal hypertension were present, with an enormous ascites, mild esophagogastric varices, associated with increased edema of the lower limbs, perineum and abdominal wall. The diagnosis was established by color Doppler ultrasonography, CT and cavography. An ilio-mesenterico-atrial shunt, between the right iliac vein, the superior mesenteric vein and the right atrium was successfully performed, transdiaphragmatically, by abdominally and right thoracic approach, using a 35 cm Dacron prosthesis. Postoperative evolution was very good. The color Doppler ultrasonography showed a good flow in the shunts. After 14 days ascites decreased over 70% and the inferior edema almost disappeared. 2 month later ascites decreased over 80%, the esophageal varices and edema disappeared completely. To our knowledge, this is the first case in the country, in which a patient underwent ilio-mesenterico-atrial shunt for Budd-Chiari syndrome and inferior vena cava extensive thrombosis.

Adult↗
PubMed1987

Color Doppler flow mapping in cardiomyopathies and prosthetic valves.

The clinical significance of color Doppler flow mapping was assessed in patients with cardiomyopathies and prosthetic valves. Left and right ventricular obstruction and mitral regurgitation can be detected in patients with hypertrophic cardiomyopathy. Specific flow patterns in the left ventricle are clearly demonstrated in dilated cardiomyopathy. Concomitant regurgitation is easily detected in patients with dilated cardiomyopathy. The major role of this technique in patients with prosthetic valves exists in the detection of prosthetic valve regurgitation. In bioprosthetic valves, differentiation between transvalvular and paravalvular regurgitation is possible. The specific complications following the mechanical valve implantation, such as an aorto-right ventricular and aorto-left ventricular communication, can be detected using this technique. Although some problems remain, this technique is useful in the management of patients with cardiomyopathies and prosthetic valves.

Bioprosthesis↗
PubMed1995

Color flow Doppler determination of transmitral flow and orifice area in mitral stenosis: experimental evaluation of the proximal flow-convergence method.

To evaluate the in vivo accuracy of color Doppler flow-convergence methods for determining transmitral flow volumes and effective orifice areas in mitral stenosis, we studied two models for flow-convergence surface geometry, a hemispheric (HS) model and an oblate hemispheroid (OH) model in a chronic animal model with quantifiable mitral flows. Color Doppler flow mapping of the proximal flow-convergence region has been reported to be useful for evaluation of intracardiac flows. Flow-convergence methods in patients with mitral stenosis that use HS assumption for the isovelocity surface have resulted in underestimation of actual flows. Chronic mitral stenosis was created surgically in six sheep with annuloplasty rings (group 1) and 11 sheep with bioprosthetic porcine valves (group 2). Hemodynamic and echocardiographic/Doppler studies (n = 18 in group 1; n = 21 in group 2) were performed 20 to 34 weeks later. Left ventricular inflow obstruction was of varied severity, with mean transmitral valve gradients in group 1 ranging from 1.3 to 18 mm Hg and in group 2 ranging from 6.3 to 25.6 mm Hg. Although transmitral flows derived by both geometric flow convergence models showed significant correlations with reference cardiac outputs, the correlations for the OH model were better than those for the HS model (group 1, r = 0.86 for the OH model vs r = 0.72 for the HS model; group 2; r = 0.84 for the OH model vs r = 0.62 for the HS model). The OH model was also superior to the HS model in determining effective orifice areas compared to reference orifice areas determined by postmortem planimetry of anatomic orifices (group 1 only, r = 0.64 for OH vs 0.58 for HS), by the Gorlin and Gorlin formula (group 1, r = 0.63 for OH vs 0.72 for HS; group 2, r = 0.82 for OH vs 0.76 for HS), and by the Doppler pressure half-time method (group 1, r = 0.76 for OH vs 0.69 for HS; group 2, r = 0.84 for OH vs 0.62 for HS).(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed1992

Two-dimensional color-mapping of turbulent shear stress distribution downstream of two aortic bioprosthetic valves in vitro.

Since artificial heart valve related complications such as thrombus formation, hemolysis and calcification are considered related to flow disturbances caused by the inserted valve, a thorough hemodynamic characterization of heart valve prostheses is essential. In a pulsatile flow model, fluid velocities were measured one diameter downstream of a Hancock Porcine (HAPO) and a Ionescu-Shiley Pericardial Standard (ISPS) aortic valve. Hot-film anemometry (HFA) was used for velocity measurements at 41 points in the cross-sectional area of the ascending aorta. Three-dimensional visualization of the velocity profiles, at 100 different instants during one mean pump cycle, was performed. Turbulence analysis was performed as a function of time by calculating the axial turbulence energy within 50 ms overlapping time windows during the systole. The turbulent shear stresses were estimated by using the correlation equation between Reynolds normal stress and turbulent (Reynolds) shear stress. The turbulent shear stress distribution was visualized by two-dimensional color-mapping at different instants during one mean pump cycle. Based on the velocity profiles and the turbulent shear stress distribution, a relative blood damage index (RBDI) was calculated. It has the feature of combining the magnitude and exposure time of the estimated shear stresses in one index, covering the entire cross-sectional area. The HAPO valve showed a skewed jet-type velocity profile with the highest velocities towards the left posterior aortic wall. The ISPS valve revealed a more parabolic-shaped velocity profile during systole. The turbulent shear stresses were highest in areas of high or rapidly changing velocity gradients. For the HAPO valve the maximum estimated turbulent shear stress was 194 N m-2 and for the ISPS valve 154 Nm-2. The RBDI was the same for the two valves. The turbulent shear stresses had magnitudes and exposure times that might cause endothelial damage and sublethal or lethal damage to blood corpuscules. The RBDI makes comparison between different heart valves easier and may prove important when making correlation with clinical observations.

Aortic Valve↗
PubMed1980

Accetability of orbital prostheses.

This study was made to determine if those patients apparently dissatisfied with an orbital prosthesis might accept an eye patch more readily. The study included 27 patients who were seen during the past 8 years. A total of 60 orbital and eye patch proshteses were prepared for the patients. Eighteen patients responded to the questionnaire. Twelve of these patients are presently wearing their prostheses, and five of them are not. Reasons given by the patients for not using their prostheses were discomfort, lack of retention, skin irritation due to daily application and removal of the adhesive, change in defect, ill-fitting prostheses, and surgical reconstruction of the site. The study shows that given a choice, 67% of the patients would prefer the orbital prosthesis. Seventy-five percent of the patients who had an eye patch would prefer an orbital prosthesis.

Acrylic Resins↗
PubMed2003

Conduit-on-valve replacement of a degenerated mitral bioprosthesis with a bioprosthesis.

Explantation of a degenerated mitral bioprosthesis with reimplantation of a new bioprosthesis is time-consuming and can be associated with several life-threatening complications. We developed a technique to simplify this procedure and avoid the complications by attaching a new bioprosthesis supported by a pericardium-covered Dacron tube to the intact stent.

Bioprosthesis↗
PubMed1999

Colour perception of laboratory-fired samples of body-coloured ceramic.

The objective of this investigation is to test by common perception, the colour fidelity of laboratory-fired samples of ceramic. Thirty-two ceramic discs were constructed in a thickness similar to that used for ceramic veneers using eight shades from each of four different manufacturers. A group of 20 'adept' observers colour matched the samples in strictly controlled viewing conditions using a Vita Lumin (Vita Zahnfabrik) shade guide. Samples were categorised as 'positive matches'(matching the expected shade), 'agreed shades' (matching an unexpected shade), or as 'unidentified shades' (no match). The Vita Lumin (Vita Zahnfabrik) colour 'value' index was used as a reference to categorise colour 'value' differences between observed and expected shade. Colour 'value' selection was divided into three groups: (1) matching colour 'value', (2) shades of higher colour 'value' than expected or (3) shades of lower colour 'value' than expected. Only six of the 32 samples examined were perceived to be 'positive matches' with the recommended shade guide. Fourteen 'agreed shades' were found while the remaining 12 shades were regarded as 'unidentified shades'. The vast majority of observations disagreed with the manufacturers' designated shade. A significant trend was found favouring higher 'value' (lighter) shades than those specified by the manufactures. Significant differences in the pattern of shade matches and disagreements between brands were also found. Alternative shade determination systems and/or ceramic colour modifications are required if colour fidelity between the shade guide and the materials tested is to be improved.

Ceramics↗
PubMed1999

Pulmonary stenosis caused by extrinsic compression of an aortic pseudoaneurysm of a composite aortic graft.

Pulmonic stenosis and stenosis of the right ventricular outflow tract related to extrinsic compression have been described in patients with tumors, in a patient with a pericardial cyst, and in patients with vascular abnormalities as an unruptured sinus of Valsalva aneurysm, a giant coronary artery pseudoaneurysm and an aortic arch aneurysm. Composite graft replacement of the ascending aorta and aortic valve with reimplantation of the coronary arteries has some inherent complications. Our case report describes a patient with a pericomposite graft aneurysm presenting as a stenosis of the pulmonary artery, detected by Doppler echocardiography.

Adult↗
PubMed1997

Operative risks of the maze procedure associated with mitral valve surgery.

Twelve patients were operated on for mitral valve disease with concomitant chronic atrial fibrillation. Valve repair was performed in five patients and replacement in seven. Maze I and maze III procedures were applied in eight and four patients, respectively, and are compared. There was a regular rhythm in all maze I patients with a constant junctional rhythm in three and an alternating sinus and junctional rhythm in the remainder. In one case, part of the left atrium was in atrial fibrillation with the remaining atria in sinus rhythm. In the maze III group, one patient was always on a regular rhythm, two had episodes of atrial fibrillation and one was in atrial fibrillation with controlled ventricular rate. Echocardiography showed atrial contraction in two maze I patients, but systolic atrial flow across both atrioventricular valves could only be demonstrated in two patients in the maze III group.

Adult↗
PubMed1995

Transoesophageal echocardiographic follow-up of patients with surgically treated aortic aneurysms.

In the present study, biplane transoesophageal echocardiography (TEE) was scheduled as part of an aneurysm surveillance programme during routine ambulatory follow-up of 37 patients following aortic aneurysm surgery. Time from surgery ranged from 3-72 months. Twenty-two patients had had aortic dissection and 15 non-dissecting aneurysms. Nineteen patients received an interposition graft of the ascending aorta, 12 valved conduit and six an interposition graft of the descending thoracic aorta. TEE showed enlargement of the sinus of Valsalva > 45 mm in seven patients. Dilatation > 45 mm of one or more aortic segments was found in four patients. An intimal flap was present in all patients, with primary aortic dissection if the initial dissection extended beyond the replaced segment. This was the case in 17 of 22 patients with aortic dissection. One to four intimal tears were identified in 15 of these patients. In all patients with intimal tears, flow was detected by colour flow Doppler in the false lumen. Thrombus formation was nil or minimal in the false lumen in 12 patients. TEE significantly influenced further management in 14 of 37 patients (38%). More frequent follow-up was scheduled in eight patients. Aortic surgery was performed electively for the second or third time in six patients based on TEE findings. We conclude that after surgical repair of aortic aneurysm, the incidence of pathological findings by TEE is high. These may have significant influence on further patient management and emphasize the need for careful follow-up.

Adult↗
PubMed1996

Aortic valve disease.

There have been several significant advances in our understanding of aortic valve disease over the past year. Recent studies suggest that "degenerative" valvular aortic stenosis is an active disease process rather than an inevitable consequence of aging. In the diagnostic evaluation of patients with aortic stenosis, detailed studies of the changes in valve area with changes in flow rate and the subaortic flow profile have been performed. In addition, the myocardial response to chronic pressure overload has been studied in further detail including gender differences in the response to chronic pressure overload. Aortic regurgitant severity can now be quantitated more precisely using simplified measures of regurgitant fraction based on Doppler and color flow imaging techniques. The optimal timing of surgical repair in chronic aortic regurgitation continues to be a topic of interest, with additional studies recommending surgical intervention prior to the development of an irreversible decrease in left ventricular contractility. Most importantly, two randomized trials of afterload reduction for preventing left ventricular dilation and symptom onset in aortic regurgitation have been performed, with the data supporting long-term afterload reduction in this patient group.

Aortic Valve Insufficiency↗