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Biomedical subjects

J F Vollmar

Publications and source records attributed to J F Vollmar.

63 records · Page 4Linked to original sources
PubMedDate not supplied

New prostheses for venous substitution.

In 81 Beagle dogs, 6 cm long segments of the inferior vena cava were replaced end-to-end by artificial vascular grafts (10 mm in diameter) without an av-fistula and anticoagulant drugs. Different graft materials have been used, such as various e-PTFE (30-90 microns fiber length) and polyurethane with low and increased microporosity. e-PTFE with 75 microns fiber length and polyurethane with increased porosity showed the best tissue incorporation, complete endothelialization of the whole length and a high patency rate of 80-85% after a follow-up of 12 months. In contrast to other commercially available vascular grafts (textile woven or knitted, e-PTFE 30 microns) tested in previous series, polyurethane and e-PTFE with increased microporosity had already achieved complete endothelialization after 6-12 weeks. Therefore, these optimized prostheses should be introduced into clinical practice for large venous substitution. Thereafter, an adjunctive av-fistula as protection is probably no longer necessary.

Animals↗
PubMedDate not supplied

Aneurysma transformation in congenital venous angiodysplasias in lower extremities.

Based on a retrospective evaluation of 107 patients with congenital venous angiodysplasia of the Type Klippel-Trenaunay (n = 76) and Type Servelle-Martorell (n = 31) the frequency and pathogenesis of aneurysma formation in the venous system has been analysed. The vascular patterns include both cylindric ectasia and fusiform aneurysms with an incidence of approximately 40%. Preferred locations are subcutaneous drainage veins, the popliteal, external iliac vein and atypic communicating veins between the superficial and the deep venous system. Complications of the aneurysm such as local thrombosis, recurrent pulmonary embolism or bleeding from ruptur were not observed. The aneurysma formation in venous angiodysplasias results probably from the causative factors: congenital weakness of the venous wall and an abnormal hemodynamical stress situation. The latter is caused by concomitant malformations of the deep venous system. The persistent intermittent venous hypertension associated with a more or less pronounced increase of the venous volume in the affected venous system of the limb results in a deep venous insufficiency respectively venous reflux disease. The therapy of choice is predominantly conservative, i.e., external compression bandages or stockings to reduce the deleterious effects of a chronic deep venous insufficiency respectively venous reflux disease. Surgery is indicated under two conditions: a) in the presence of aneurysm complications or b) for the elimination of a pathological short circuit flow in some drainage veins. Antireflux surgery, i.e., venous valve transfer from the brachial vein, is up to recently still in a stage of experimental-clinical investigation.

Adolescent↗
PubMedDate not supplied

Perigraft-reaction after implantation of vascular prostheses. Pathogenesis, clinical picture and treatment.

This report is based on 18 perigraft reactions in 2237 implanted vascular prostheses (1970-1985). The incidence of this complication is 6.8-9.5/1000 both for Dacron-double-velour and expanded PTFE-prostheses. The clinical picture is characterized by localized or extended fluid accumulation around the artificial graft (perigraft cysts or "swimming prosthesis"). Including 271 reports from the literature, 75% of vascular prostheses in extraanatomical positions were affected. The time interval between vascular substitution and clinical manifestation is on average 23.5 months. The pathogenesis of this aseptic late complication is still unclear. Several disposing factors are under discussion: (a) physico-chemical irritation of the surrounding tissue by the fabric itself (release of monomers, emulgators etc.), (b) mechanical trauma (continuous movement of the graft in the tissue bed, i.e. insufficient tissue fixation resulting in gaps and exudation of fluid round the prosthesis), (c) latent or manifest renal insufficiency. The partial or total removal of the affected prosthesis and its substitution by another type of vascular prosthesis offers the best chance of definitive cure. Repeated puncture of perigraft cysts produces frequent recurrencies and the danger of secondary infections. Therefore only an exchange of the graft can be recommended.

Aged↗
PubMedDate not supplied

Robert May memorial lecture: Advances in reconstructive venous surgery.

During the last decade progress in reconstructive venous surgery is mainly based on improvements of preoperative diagnosis and on changed surgical techniques (e.g. intraoperative lumen control by vascular endoscopy or angiography; temporary arteriovenous fistulas as protective measure; external supported vascular prostheses as substitutes). The main indications include acute ilio-femoral phlebothrombosis, vein injuries and in selected cases the substitution of big veins in extended tumor surgery. The late results of venous thrombectomy in the ilio-femoral segment could be remarkably improved due to changed techniques of lumen restoration (combined ring- and balloon-disobliteration, temporary a.v. fistula in inguinal or popliteal position). In patients with persisting central occlusions in the iliac veins a second repair may be considered using a suprainguinal cross-over graft (external supported e-PTFE-prosthesis). For post-thrombotic syndrome with pronounced deep venous insufficiency reconstructive procedures afford a critical selection of patients (Palma-operation, Husni-May-operation, interposition of valve bearing venous segments in the superficial femoral vein). The remarkable contribution given by R. May to the advances in venous surgery is illustrated.

Blood Vessel Prosthesis↗
PubMedDate not supplied

Aorto-enteric fistulas as postoperative complication.

This report is based on 15 own observations and 164 patients collected from the literature. The most frequent location both of primary and secondary aortic-enteric fistulas (AEF) is the end part of the duodenum (60-70%). In the group of secondary AEF the paraprosthetic type represents the most frequent morphological finding. The best diagnostic approach should be seen in a gastroduodenoscopy. The choice of surgical repair is still controversal. Most of the surgeons insist on a radical repair (Type A: restoration of the intestinal tract, complete removal of the vascular prosthesis, blind closure of the infrarenal aortic stump, axillo-bifemoral bypass). Type A repair is loaded with a high operative mortality (52%) and a number of secondary complications (e.g. recurrent AEF; bleeding from the aortic stump). As an alternative surgical approach the author present an in-situ-repair (Type B: closing of the intestinal defect, partial exchange of inserted vascular prosthesis, an encircling omentum sleeve covering the prosthesis and anastomoses). The Type B repair offers a time saving procedure with a reduced operative mortality (26%) and a better outcome for the patients. This method is only contraindicated in the presence of a spread infection of the retroperitoneal space including the vascular prosthesis.

Aorta, Abdominal↗
PubMedDate not supplied

Aneurysms of the infrarenal abdominal aorta: principles and results of surgical treatment.

With the surgical treatment of closed abdominal aortic aneurysms, the patient can have long-term survival and the danger of rupture can be avoided. Surgical repair on asymptomatic closed aneurysms can be performed with a very low risk (a mortality rate of below 1%). The main prerequisite for such protective surgery is an early diagnosis, best done by a routine check-up of all elderly people suffering from arterial hypertension, peripheral occlusive disease or other signs of arteriosclerosis. Computerized tomography (CT) and the ultrasound technique have gained a predominant position in such protective screening programs. Through the standardization and simplification of the operative techniques, surgical repair has been made simpler, safer and shorter, and the operative risk for patients with intact aneurysms has been remarkably reduced. A ten-year retrospective evaluation of 162 operated patients demonstrates a reduction in operative mortality from 14.3% to 2.8% in the group of patients with nonruptured aneurysms in the last period (1975-1979). On the other hand, progress has been made much more limited in surgery for ruptured aneurysms (operative mortality only reduced from 61.1% to 52.3%). The repair of closed or ruptured aortic aneurysms should be mainly restricted to special units with a highly trained surgical team. This type of surgery should no longer be the subject of occasional intervention by general surgeons.

Aorta, Abdominal↗