We further developed our heterotopic pig model of obliterative bronchiolitis to study airway obliteration in xenografts.Four domestic piglets each received 40 bronchial xenografts s.c. from a donor lamb. Piglet X was not immunosuppressed. The other animals received daily oral cyclosporine, 15 mg/kg (XC), or SDZ RAD, 1.5 mg/kg (XR), or both (XCR). Five implants at a time were serially removed from each animal during 17 days for histological assessment.In contrast to the grafts of the others, the xenografts of XCR recovered after initial ischemic damage. No epithelial damage (P<0.01) or mural necrosis occurred on day 7. Airway obliteration developed in all, but was significantly delayed in XCR.Invariably developing airway obliteration in nontreated xenografts was delayed by immunosuppression, making the model useful, especially in testing the efficacy of immunosuppressive drugs in a xenogeneic system.
A total of 90 grafts of 100 mm in length was inserted as arterial and shunt conduits in 31 mongrel dogs. Histological changes before and after implantation were evaluated. Sections were stained with van Gieson, haematoxylin eosin and Wiegert's method for elastic fibres, and studied with light microscopy. Twenty five of the 42 cases studied showed classic signs of rejection around the graft, the strongest immunological response being seen in the fresh vein grafts. Glutaraldehyde pre-treatment diminished this reaction but it was still clearly visible in 13 of the 21 cases. Of the fourteen human umbilical vein grafts tanned with glutaraldehyde and used either as shunts or bypass grafts, seven showed only slight or moderate reaction and in seven cases no clear sign of rejection could be seen. The absence of intimal hyperplasia with this type of graft also showed its superiority over that of the human "non-umbilical" vein grafts. The problem in all the groups was the anastomotic area, where fibrous hyperplasia developed. The graft structure seemed to be well-preserved during the follow-up period of 6.0 months.
Summary Platelets play a key role in (sub)acute thrombotic occlusion after stenting. We examined the possible differences between biodegradable polylactide (PLA) and stainless steel (SS) stents in platelet attachment and morphology after whole blood perfusion. PLA stents of different configurations (spiral/braided) and polycaprolactone-polylactide (PCL-PLA)-coatings, or SS stents were implanted into a PVC tube (Ø 3.2 mm), with or without precoating of the tube with type-I collagen. PPACK (30 µM)-anticoagulated blood with 3H-serotonin prelabeled platelets was perfused (flow rate: 30 ml/min, 90 s) over the stents. Platelet deposition was assessed by scintillation counting and morphology by scanning electron microscopy (SEM). To examine coagulation activation, plasma prothrombin fragments (F1+2) were measured before and after the perfusion. Protein deposition on PLA/SS stents was assessed at augmented shear forces mimicking coronary flow (rate: 60 ml/min, 60 s) under minimal anticoagulation (PPACK 1 µM). More platelets deposited on PLA stents than on SS stents under all study conditions (p <0.03). Under anticoagulation (PPACK 30 µM) the generation of F1+2 remained unaltered. Under higher flow rate and limited anticoagulation SS stents accumulated 3.27 ± 0.75 µg and PLA stents 5.25 ± 1.74 µg of protein (Mean ± SD, p <0.95). Among all biodegradable stents, the braided PLA stent coated with PCL-PLA-heparin accumulated the fewest platelets (p <0.02). In SEM, signs of platelet activation on braided heparin-coated PLA stents, when compared with uncoated braided PLA/SS stents, appeared modest. In conclusion, PCL-PLAheparin coating of biodegradable stents may enhance their hemocompatibility, expressed by less platelet deposition. Nevertheless, materials, design, and coating techniques of biodegradable stents must be further developed.
Ruptured sinus Valsalva aneurysm was repaired in 13 patients (mean age c. 33 years). Dyspnea, chest pain, fatigue and palpitation were the most common symptoms and systodiastolic murmur, cardiomegaly and pulmonary congestion the most pertinent clinical findings. The pulmonary-to-systemic flow ratio averaged c. 2.5. Associated cardiac anomalies were ventricular septal defect, aortic or mitral regurgitation, aortic coarctation or subvalvular stenosis, tetralogy of Fallot (altogether 8 cases). The origin of the fistula was the noncoronary, right coronary or left coronary sinus (5, 4 and 3 cases) or was not identifiable (1 case). Rupture occurred into the right atrium (6 cases), right ventricle (6) or pulmonary artery (1 case). Repair was undertaken through aortotomy (6 cases), right ventriculotomy (2) or right atriotomy (1) or through aortotomy+right ventriculotomy or atriotomy (4). In one case aortic valve replacement was performed. All survived the operation. Follow-up averaged 9.6 years. Recurrent fistulation, though with small shunt, was found in two cases. Combined two-dimensional and Doppler echocardiography revealed minor cardiac abnormalities in most patients, particularly aortic regurgitation. All the patients were in NYHA function class I or II.
