Introduction of a flexible polymeric heart valve prosthesis with special design for mitral position.

BACKGROUND: Current heart valve prostheses are constructed mimicking the native aortic valve. Special hemodynamic characteristics of the mitral valve such as a nonaxial central inflow with creation of a left ventricular vortex have so far not been taken into account. A new polycarbonaturethane (PCU) bileaflet heart valve prosthesis with special design for the mitral position is introduced, and results of animal testing are presented. METHODS AND RESULTS: After in vitro testing, 7 PCU-prostheses and 7 commercial bioprostheses (Perimount, n=4; Mosaic, n=3) were implanted in mitral position into growing Jersey calves (age 3-5 months, weight 60-97 kg) for 20 weeks. 2-Dimensional echocardiography was performed after implantation and before sacrification. Autopsy included histologic, radiographic, and electron microscopic examination of the valves. In vitro durability was proven for >15 years. After implantation 2-dimensional-echocardiography showed no relevant gradient or regurgitation of any prosthesis. Clinical course of the animals with PCU valves was excellent. In contrast, 5 of 7 calves with bioprostheses were sacrificed after 1-9 weeks because of congestive heart failure. 2-Dimensional echocardiography of the PCU valves after 20 weeks showed mild leaflet thickening with trivial regurgitation; mean gradient was 8.1+/-5.0 mm Hg (weight: 160-170 kg). The explanted PCU prostheses revealed mild calcification and no structural degeneration. All of the Perimount bioprostheses were severely calcified and degenerated after 11+/-7 weeks. One Mosaic bioprosthesis was thrombosed after 1 week, and 2 showed severe and mild-to-moderate degeneration after 4 and 22 weeks, respectively. CONCLUSIONS: Polycarbonaturethane valve prostheses with special design for mitral position show excellent hemodynamic performance and durability in vivo. Calcification and structural changes are mild compared with bioprostheses. Controlled clinical studies are planned.

Occult celiac disease prevents penetrance of hemochromatosis.

AIM: To report a patient with C282Y homozygocity, depleted body iron and intestinal atrophy caused by celiac disease (CD) who experienced resolution of the enteropathy with subsequent normalization of iron metabolism upon gluten-free diet. METHODS: To obtain information on the tissue distribution and quantitative expression of proteins involved in duodenal iron trafficking, we determined the expression of divalent-metal transporter 1 (DMT1), ferroportin 1 (FP1) and transferrin receptor (TfR1) by means of immunohistochemistry and real-time PCR in duodenal biopsies of this patient. RESULTS: Whereas in hereditary hemochromatosis patients without CD, DMT1 expression was up-regulated leading to excessive uptake of iron, we identified a significant reduction in protein and mRNA expression of DMT1 as a compensatory mechanism in this patient with HH and CD. CONCLUSION: Occult CD may compensate for increased DMT1 expression in a specific subset of individuals with homozygous C282Y mutations in the hemochromatosis (HFE) gene, thus contributing to the low penetrance of HH.

Biocompatibility and healing process of polyester meshes in the brain: in vivo examination in rats.

OBJECTIVES: To analyze the biocompatibility of multifilament polyester (PET) meshes used for the implantation of auditory brainstem implants in a standardized Wistar rat model (n=29). METHODS: The physical properties of the meshes were examined during surgery. Using a modified plastic embedding, the local tissue reaction and the stability of mesh position in the region of the fourth ventricle were evaluated in section series from day 3 to 64. The cellular reaction was further differentiated using transmission and scanning electron microscopy. RESULTS: PET meshes were stable for handling. However, sharp edges inevitably led to brainstem and cerebellar penetration in some cases. The meshes were preserved in situ in all section series. Positioning was stable with one exception. A sufficient fibroblast and collagen fiber encasement was reached after 14 days. In all cases, no further change was observed through day 64. The host-defense reaction was persistent and characterized by numerous macrophages and foreign-body giant cells. Bacterial infection occurred in three cases. CONCLUSIONS: PET meshes proved to have an acceptable biocompatibility regarding local-tissue reaction in the brain. Modified polymer structures should be developed to reduce risk of injury. Anti-inflammatory surface treatments and monofilament meshes could reduce the infection rate.

Introduction of a flexible polymeric heart valve prosthesis with special design for aortic position.

OBJECTIVE: Current prosthetic heart valves necessitate permanent anticoagulation or have limited durability and impaired hemodynamic performance compared to natural valves. Recently a polymeric valve prostheses with special design for mitral position demonstrated excellent in vitro and in vivo results with improved durability and no need for permanent anticoagulation. In this study, a respective flexible polymeric aortic valve is presented and in vitro and in vivo results are reported. METHODS: The aortic prosthesis (ADIAM lifescience AG, Erkelenz, Germany) is entirely made of polycarbonaturethane. The tri-leaflet flexible prosthesis mimicks the natural aortic valve and has a diminished pressure loss and reduced stress and strain peaks at the commissures. The valve underwent long-term in vitro testing and in vivo-testing in a growing calve animal model (20 weeks, 7 aortic valves) and was compared to two different commercial bioprostheses. RESULTS: The polymeric aortic heart valve substitute demonstrated excellent in vitro and in vivo hemodynamics. Five/seven animals with aortic PCU-prostheses had an excellent clinical long-term course. The explanted valves showed a variable degree of calcification. Two of the seven animals died at 27 and 77 days due to pannus overgrowth causing severe LVOTO without degeneration of the valve itself. Both animals with commercial bioprostheses had to be sacrificed because of congestive heart failure related to structural degeneration of the bioprosthesis after 10 and 30 days of implantation. There was no increased thrombogenity of the PCU valves compared to bioprostheses. CONCLUSION: The new flexible polymeric aortic valve prosthesis is superior to current bioprostheses in animal testing.

New flexible polymeric heart valve prostheses for the mitral and aortic positions.

OBJECTIVE: Current prosthetic heart valves necessitate permanent anticoagulation or have limited durability and impaired hemodynamic performance compared with natural valves. We report in vivo and in vitro results with new polymeric valve prostheses that have a special design for the mitral and aortic positions. The aims are improved durability and elimination of the need for permanent anticoagulation. METHODS: The mitral and aortic prostheses (Adiam Life Science, Erkelenz, Germany) are made entirely of polycarbonate urethane (PCU). The bileaflet asymmetric mitral valve mimics natural, nonaxial inflow, which creates a left ventricular vortex, saving energy for systolic ejection of blood. The trileaflet aortic prosthesis has diminished pressure loss and reduced stress and strain peaks at the commissures. The valves were subjected to long-term in vitro testing and in vivo testing in a growing calf model (20 weeks; 7 mitral and 7 aortic valves) with comparison with 2 commercial bioprostheses (7 mitral, 2 aortic). Two-dimensional echocardiography was performed after implantation and prior to sacrifice with autopsy and valve examination. RESULTS: In vitro durability of the PCU valves was proved up to 20 years. In vivo durability and hemodynamics were superior to those of all bioprostheses. Survival of PCU valves versus bioprostheses was 7 versus 2 mitral valves and 5 versus 0 aortic valves, respectively. Two animals with PCU aortic valves died of pannus overgrowth that caused severe left ventricular outflow tract obstruction without changes in the valves. Degeneration and calcification were mild (mitral) and moderate (aortic) in PCU valves but were severe in biological valves. There was no increased thrombogenicity of the PCU valves compared with bioprostheses. CONCLUSION: The new flexible polymeric aortic and mitral valve prostheses were superior to current bioprostheses in animal testing.

Hypertensive pulmonary vascular disease in adults with secundum or sinus venosus atrial septal defect.

BACKGROUND: The development of hypertensive pulmonary vascular disease (HPVD) is considered a risk factor in the long-term course of patients with secundum atrial septal defects (ASD). The aim of this study was to assess the prevalence and histologic degree of HPVD and pulmonary hypertension in relation to preoperative clinical and hemodynamic data, intraoperative findings, and operative outcome in adults. METHODS: Lung biopsies of 75 patients, mean age 44 +/- 14 years (18-71 years), with secundum ASD or sinus venosus defect including ten patients with partial anomalous pulmonary venous return were analyzed in accordance with preoperative and intraoperative findings as well as operative outcome. Lung biopsy was performed at the time of defect closure and was classified according to Heath and Edwards. RESULTS: Structural changes of the pulmonary vasculature were found in 59% of patients; grade 3 and higher changes were present in 19%. There were no statistically significant relations between histologic findings and preoperative clinical and hemodynamic data, intraoperative findings, and operative outcome. The prevalence of moderate (32-50 mm Hg) and severe (> 50 mm Hg) systolic pulmonary hypertension was 27% and 17%, respectively. Increased systolic pulmonary arterial pressure was associated with increased pulmonary vascular resistance (p < 0.000) and patients' age (p = 0.001). Patients with a lower functional capacity had a higher prevalence of pulmonary hypertension (p = 0.011). CONCLUSIONS: The prevalence of HPVD and pulmonary hypertension in adult patients with secundum ASD or sinus venosus defect is considerable. Preoperative hemodynamic data do not predict the degree of HPVD in lung biopsy. Closure is generally advised to prevent increasing pulmonary arterial pressure and decreasing functional capacity over time.

Functional upper airway obstruction in a child with Freeman-Sheldon syndrome.

Freeman-Sheldon syndrome is defined as a combination of microstomia, deep set eyes, small palpebral fissures, arthrogryposis with ulnar deviation of the hand, talipes equinovarus and generalized muscular hypertension. Respiratory and swallowing problems are frequently encountered in these patients due to small orifices of mouth and nose. Obstruction of the upper airway tract resulting in tracheostomy has only been described twice. The described child manifested the typical dysmorphic features of Freeman-Sheldon syndrome and suffered from serious respiratory distress and swallowing difficulties from birth. The boy died at the age of 7 months after accidental decannulation of the tracheostoma during sleep. He did not show anatomical or histopathological abnormalities in the pharyngeal, laryngeal or tracheal regions. We assume that the only explanation of the repeated obstructive episodes is a functional muscular obstruction.