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Biomedical subjects

E Wolner

Publications and source records attributed to E Wolner.

At least 289 records · Page 16Linked to original sources
PubMed1991

[Stented dilated or varicose veins as arterial bypass transplants: experimental and initial clinical results].

Dilated and varicose veins are usually not used as arterial bypass-grafts despite they are lined with functional endothelium. External support by a constrictive mesh tube could conform these veins into evenly calibrated bypass-grafts. Ovine jugular veins could be constricted from 15 to 6 mm diameter without forming folds on the inner flow surface. 6 months after implantation of 5 cm long jugular vein segments into the carotid arteries of 7 sheep the inner diameter was 19.5 +/- 3.3 mm for native veins (n = 4) and 7.6 +/- 0.8 mm for constricted veins (n = 10). Intimal hyperplasia was reduced from 0.4 +/- 0.2 mm in native to 0.23 +/- 0.07 mm in reinforced veins (p = 0.03). Mesh tube constricted varicose veins were used as bypass material in 11 infrainguinal reconstructions. All grafts were well calibrated at control angiography. External constriction by mesh tubes is a means to convert varicose veins into suitable bypass grafts.

Aged↗
PubMed1991

[Risk factors for local recurrence of rectal carcinoma].

The impact of distal resection margins and the mode of operation on pelvic recurrence rate was assessed in 331 cases following abdomino-perineal resection (APR; n = 134), and anterior resection (AR; n = 197) for rectal cancer. Local recurrence was observed in 55 cases (16.6%) after a median interval of 16 months. Only 20 of 212 patients (9.4%) without positive lymph nodes developed a local recurrence, but 35 of 119 (29.4%) with nodal involvement. The recurrence rate was 33% (10/30) in cases with local spread to adjacent structures (T4), and 15% in cases with less extensive penetration. Of 59 poorly differentiated cancers 15 developed pelvic failure (25%), as opposed to 40 of 272 (14.7%) well or moderately differentiated tumours. 17.7% developed local recurrence after AR, and 14.9% after APR. The recurrence rate following AR was 30% in 33 cases with resection margins less than or equal to 10 mm and 17.4% in 115 cases with margins from 11 to 40 mm, and 10% in 49 cases with wider margins. Cox's multiple proportional hazards regression revealed that nodal involvement (p = 0.0003), local invasion (p = 0.0055), poor differentiation (p = 0.066), and AR vs. APR (p = 0.099) were independent risk factors for pelvic failure. For the AR cases the factors were nodal involvement (p less than 0.0001), local invasion (p = 0.0043), and a resection margin less than or equal to 25 mm on the fixed specimen (p = 0.0039). For patients with negative lymph nodes local invasion was the only independent risk factor, whereas the variables "anterior resection" and narrow resection margin were significant only in node positive cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Resection of lung metastases. Results and prognostic factors].

249 thoracotomies for lung-metastases were performed in 202 patients at the 2nd Dept. of Surgery of the Vienna University Clinic till 1989. Age ranged from 2 to 78 years, 14 patients were younger than 18 years. The primary tumour was a carcinoma in 143 cases, a sarcoma in 45 cases and a melanoma in 14 patients. The primary tumour in the young patients was osteosarcoma in 8 cases, Ewing sarcoma in 2 cases and Wilms tumour in 2 patients. With a minimal follow up period of 2.5 years the 5-years-survival after metastasectomy was 42% for patients with carcinoma and 29% for the sarcoma patients. None of the patients with melanoma survived 5 years. A significant difference was found between the carcinoma and sarcoma groups with respect to survival rate. A prognostic factor was the disease-free interval in carcinoma patients. Actuarial post-thoracotomy survival in patients with osteogenic sarcoma was 34% at 5 years and 18% in the soft-tissue sarcoma group. Size of lesion, vitality of the metastases and the disease free interval correlated with survival in the osteogenic group, whilst the number of lesions was of importance in the soft-tissue group. On account of the lesser functional morbidity and the enablement to assess both lungs for treatment, the median sternotomy is recommended for cases with bilateral lung metastases. The results justify an aggressive surgical approach for the treatment of lung metastases.

Adolescent↗
PubMed1991

[Successful bridge transplantation with the Vienna artificial heart].

The Vienna Heart, a pulsatile artificial ventricle, vacuum-formed from Pellethane has been used successfully as total artificial heart (TAH) and left ventricular assist device (LVAD) to bridge over patients in terminal heart failure. A 50 year-old patient with cardiomyopathy had to be resuscitated and was transferred in cardiogenic shock, with impaired renal and liver function. 6 days after orthotopic implantation of a Vienna TAH a suitable donor organ was found and the patient was transplanted. 7 weeks later he was discharged and is alive and well now. A 40-year-old patient was transferred in cardiogenic shock 22 days after recurrent anterior infarction. Due to renal failure he was on haemofiltration. Congestive liver failure caused a severe coagulation disorder so a Vienna LVAD was implanted without the use of extracorporeal circulation. Despite development of septicaemia he was transplanted 24 days later. It was thought that either the ventricular thrombus or the LVAD was the septic focus. All consecutive blood cultures have been negative and he was discharged 6 weeks later. To our knowledge, case 1 represents the first successful bridging with a non-Jarvic TAH. The second case shows that sepsis is not necessarily a contraindication to heart transplantation.

Adult↗
PubMed1991

[The role of intestinal resection in primary surgery of ovarian carcinoma].

In most ovarian cancer cases complete resection of the tumour masses is not possible, and tumour reduction at the primary operation has been shown to improve survival. In some cases optimal tumour reduction is only possible by resecting intestinal structures, and it remains to be shown whether aggressive approaches are justified. The impact of intestinal resection, among other prognostic factors, was analysed in 104 patients undergoing primary operation for ovarian cancer. Tumour spread to bowel, exceeding 2 cm in diameter occurred in 39% of the cases. Debulking to a maximal tumour diameter less than 2 cm was achieved in 68 (65%) cases. Successful debulking was achieved by performing large (n = 20) and small bowel (n = 4) in 22 patients with massive bowel involvement. Two patients died during the hospital stay, one after bowel resection. Four independent prognostic variables emerged from Cox's multiple proportional hazards regression: ascites (p = 0.001), massive bowel involvement (p = 0.007), residual tumour size (p = 0.002), and intestinal resection (p = 0.11). The authors contend that intestinal resection to achieve optimal tumour debulking at the primary operation will improve the survival of ovarian cancer patients.

Adolescent↗
PubMed1990

The influence of sample age on collagen-induced platelet aggregation in whole blood.

Whole blood electrical aggregometry (WBEA) has become an accepted method to gain quick information on platelet disorders. Compared to the optical method WBEA is closer to physiology and less complicated, but on the other hand more difficult to standardize. Different approaches have been attempted in the past to improve the reliability and practicability of this technique. The influence of sample age has not been defined so far. In a first step a mathematical modelling program was established, which is able to characterize the aggregation curves obtained after collagen stimulation. In a mathematical analysis various characteristics of the curve function were calculated and their sensitivity for aging investigated. Regression was performed for each characteristic, and correction factors defined. Our results indicate, that whole blood specimen for collagen induced aggregation can be used without correction factor up to 30 minutes. Data obtained with an age exceeding half an hour have to be corrected following a quadratic regression.

Blood Preservation↗
PubMed1990

[The patient following heart valve replacement].

Results of heart-valve-surgery based on a large group of patients of the University-hospitals in Vienna are given. Problems such as anticoagulant therapy and the prevention of prosthesis-endocarditis are shown.

Anticoagulants↗
PubMed1990

[Use of an artificial heart and ventricular support system before heart transplantation].

Acute, uncontrollable heart failure in young candidates for transplantation should be considered an indication for implantation of an artificial heart or artificial support of the hear ventricle, if a suitable graft for transplantation is not available at the time. It may be assumed that the two systems will ensure an adequate circulation and will improve organ function. The success of two-stage transplantation is cca 50%. Postoperative haemorrhage and infection are a major problem. Infection after implantation of an artificial heart is frequently incurable and is a clear contra-indication for further implantation. Thromboembolism caused by the artificial blood pump does not seem to be a serious complication when used temporarily. As none of the patients died due to failure of the pump and as also the other problems associated with the use of an artificial heart or a supporting device were successfully resolved, research and development of artificial blood pumps should proceed. Clinical results also confirmed the success of two-stage transplantation of the heart.

Heart Transplantation↗
PubMed1990

Mechanical simulation of shear stress on the walls of peripheral arteries.

In the last few years many attempts were made to line artificial vascular grafts with in vitro grown endothelial cell layers and thereby to minimize the risk of thromboembolism. However, adherence and resistance against shear stress forces were not tested under physiological pulsatile shear stress forces. In this paper, a mock-circulation apparatus is described, which simulates various forms of pulsatile shear stress, and which at the same time meets the requirements of cell cultivation. It can be sterilized and needs less than 700 ml of culture medium for priming. The generated flow profile can be adapted to a wide range of shear stress and also to different viscosities of used media. To take account of the different viscosities of culture medium and blood, a computerized calculation of the shear stress pattern was performed. Using the results of this computer model, the flow pattern was modified to obtain normal physiological shear stress when using culture medium. Results of pulse generation and simulation for the superficial femoral artery are presented.

Arteries↗
PubMed1990

Treatment of postpneumonectomy empyema.

Postpneumonectomy empyema with or without (bronchopleural) fistula is an infrequent but serious, and often life-threatening complication. In 20 of our patients postpneumonectomy empyema was discovered. The time interval between original operation and discovery of the empyema varied from 9 days to 9 years. In two cases, the empyema had been found and treated initially at another hospital but not adequately, so that at the time of treatment by us the bronchopleural fistula had already been present for 8 and 19 years. In 13 cases a bronchial stump fistula was discovered. In five patients the fistula was successfully closed endoscopically with glue. In one patient closure was performed by transmediastinal stump resection, in three patients with a fistula thoracoplasty was performed. In three patients we achieved closure by transposition of pedicled muscle flaps. In one of these patients a septic condition could be mastered by performing window thoracotomy. Two patients without fistula were successfully treated with irrigation, and two further patients with thoracostomy. In one patient recovery was achieved by medication after puncture. Two patients died of sepsis and after thoracoplasty. If a fistula is present, drainage with irrigation and endoscopical glueing should be the initial treatment. This should be followed by resection of the bronchial stump. If there is no fistula or if the stump is too short thoracostomy is the treatment of choice. If it is not successful thoracoplasty has to be performed.

Adhesives↗
PubMed1990

Action of endogenous atrial natriuretic peptide in calves with experimental acute central venous congestion and low cardiac output.

STUDY OBJECTIVE: The aim of the study was to investigate plasma concentrations of atrial natriuretic peptide, aldosterone, and renin during experimentally induced acute central venous congestion. DESIGN: Two experimental calf models were used: (1) right heart failure due to pulmonary artery obstruction; (2) inferior vena cava syndrome produced by inferior vena caval obstruction. Hormonal responses and haemodynamic variables were measured over 6 h. SUBJECTS: Experiments were performed on three female "Schwarzbund" calves, age 3 months, weight 92 +/- 8 kg. MEASUREMENTS AND MAIN RESULTS: In the pulmonary artery obstructed group there was an increase of plasma aldosterone from 6.5(SEM 1.6) to 22.1(3.2) ng.dl-1 (p less than 0.05), of renin from 0.7(0.1) to 2.5(0.3) Goldblatt units x 10(-4).ml-1 (p less than 0.05), and of atrial natriuretic peptide from 22.1(4.5) to 141.4(27.8) pmol.litre-1 (p less than 0.05). During inferior vena caval obstruction, aldosterone increased from 2.4(0.4) to 20.9(2.0) ng.dl-1 (p less than 0.05), and renin increased from 0.4(0.05) to 2.0(0.20) Goldblatt units x 10(-4).ml-1 (p less than 0.05). In this experiment, atrial natriuretic peptide remained unchanged. Cardiac output decreased in both groups. There was significant fluid and electrolyte retention during both experiments, with urine volume decreasing from 87.7(11.6) to 35.0(1.2) ml-h-1 in experiment (1), and from 185(14) to 95.7(8.6) ml.h-1 in experiment (2). CONCLUSIONS: The study suggests (1) that in an experimental acute state of reduced cardiac output due to pulmonary artery stenosis with constantly increased right heart pressures, raised endogenous atrial natriuretic peptide failed to induce diuresis and natriuresis; (2) that in acute right heart failure, renin and aldosterone secretion could not be suppressed by raised atrial natriuretic peptide concentrations; and (3) atrial natriuretic peptide secretion seemed to be exhausted after 6 h continuous atrial distension.

Acute Disease↗
PubMed1990

Noise level and perception of the closing click after heart valve replacement with St. Jude Medical and Björk Shiley Monostrut prostheses.

The metallic click generated by the closure of mechanical heart valve prostheses may severely bother patients, but generated sound energy and the extent of complaints after implantation are not known. In 62 patients, after valve replacement with St. Jude Medical (SJM) (n = 35) and Björk Shiley Monostrut (BSM) (n = 27) prostheses, sound energy was recorded with a calibrated noise level analyzer at 5, 10, and 100 cm distance from patients and correlated with their complaints. At a distance of 100 cm, the BSM valves produced a significantly higher sound pressure level, 30.5 +/- 5 db(A), compared to the SJM valves, 24.1 +/- 4 db(A) (p = 0.0001). There was no significant difference at shorter distances. After splitting into frequency bands the highest sound pressure levels were observed in the high frequency ranges (8 to 16 kHz) representing the metallic click. BSM valves produced higher sound levels in all frequency ranges at 1 m distance. Seventy-three percent of all patients were aware of the noise generated by the valve; 20% had disturbed sleep; and 26% preferred a less noisy valve type. Twelve of 27 patients with BSM valves wanted less noisy valves, whereas only 4 of 35 patients with SJM valves wished to have a less noisy valve type (Chi-square p = 0.003). In patients who could hear their valve measured, sound level was higher than in patients who could not. In 9 of 27 patients with BSM (33%), versus 3 of 35 with SJM prostheses (9%), the clicking caused sleep disturbances.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustics↗
PubMed1990

A method for constricting large veins for use in arterial vascular reconstruction.

A satisfactory biologic graft can be created if dilated, but otherwise unusable veins are wrapped with a constrictive mesh tube. The purpose of this study was to determine whether a resorbable constrictive tube creates an appropriately sized vascular graft by induction of neoarterial wall growth. In 8 sheep a 5 cm segment of the carotid artery was resected and the external jugular vein inserted as a tubular graft. The vein was either wrapped with a polydioxanon (PDS) reinforced polyglactin (Vicryl) mesh (n = 4), a Vicryl mesh (n = 4), or a Dacron mesh tube (n = 3) to achieve a diameter reduction to 7 mm. Or the vein was used without reinforcement (n = 3). At angiography after 6 months the unreinforced veins had a diameter of 19 mm (range 15-22). The Vicryl reinforced veins measured 9.4 (8.5-10) mm, but 3 of 4 developed aneurysmatic dilatations at sites of valve sinuses with a mean diameter of 19 (15-21) mm. PDS reinforced veins measured 7.4 mm (7.1-7.9). Two of 4 had minor aneurysms of 13 and 16 mm. The two remaining PDS reinforced grafts were indistinguishable from the native artery. Dacron tubes reduced the vein size reliably to 7.6 (7.5-7.9) mm, but showed narrowing at the proximal anastomoses (PDS 7.2 +/- 0.4, Dacron 6.1 +/- 0.4, p = 0.016). PDS wrapping reduced maximal graft diameter to 10.9 +/- 4 mm as compared to that of the native vein, 18.7 +/- 3.5 (p less than 0.05). Resorbable meshes can reduce the diameter of a venous graft by strengthening the vessel wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The influence of temperature on somatosensory-evoked potentials during cardiopulmonary bypass.

Somatosensory-evoked potentials (SEPs) after median nerve stimulation were recorded in 10 neurologically normal patients during cardiopulmonary bypass and hypothermia. In all patients the changes of the latencies (spinal N13, cortical N20 and N35) and the central conduction time during cooling, and the decrease in latencies during rewarming was described by a gamma function. The analytic discussion of pooled data of all patients led to another SEP-latency-temperature relationship than the observation of each single patient. In 6 of 10 patients there was found a maximum of latency increase before the minimal temperature was reached. The cooling and the rewarming curve had to be considered separately. Latency changes of SEPs during hypothermia are discussed as a very complex phenomenon influenced by many technical and patient factors. This reduces the value of SEPs as an index of central nervous system integrity during open heart surgery and hypothermia.

Adult↗
PubMed1990

[Experimental studies of extracellular matrix constituents for coating artificial prostheses before endothelialization].

Endothelialization seems to be a possibility to reduce thrombogenicity of artificial vascular prostheses. We have been occupied to find an ideal coating for the cells. Substances of extracellular matrix (ECM) were used: human fibronectin (HFN), laminin, collagen type I + III + IV. We have compared the influence of these materials with regard to adherence, sheer stress resistance and growth of cultivated human vena saphena endothelial cells (SEC). There was not any statistically significant difference according to cell proliferation. During a cultivation period of 7 days SEC increased by population doubling number 5 corresponding to a population doubling time of 76 hours. PTFE prostheses were coated with the materials, seeded with SEC and exposed to sheer stress in a physiological perfusion unit. Adherent SEC were counted after 24 hours of perfusion. Counts were correlated to the number of seeded cells. After perfusion only 23 +/- 4%, resp. 25 +/- 6% of cells were counted on collagen I + IV + HFN and on collagen I + IV + laminin. We found better results on collagen I + III and on collagen I + III + HFN; there were adherent 55 +/- 5%, resp. 53 +/- 7% after perfusion. These results document that there is no difference for SEC cultivation on different native components of basal membrane, under sheer stress conditions there seems to be differences in cell adherence.

Blood Vessel Prosthesis↗
PubMed1990

[Infections in organ transplantations].

Since cyclosporin A was introduced clinically, transplantation of solid organ grafts, has become a routine therapy for untreatable endstage-diseases of various organs, such as kidney, liver, heart and lung. Nowadays the most frequent cause of mortality and severe morbidity in transplant recipients is not graft rejection but infection. During the first three postoperative months organ recipients are extremely endangered for infectious diseases. Patients receive high dosages of immunosuppressive therapy, because immunogenecity of the graft is rather high. In course of the following months the allograft is more and more accepted by the recipients immune system. Consecutively immunosuppression is reduced and the risk of infection is diminished. --During the first postoperative month bacterial infections commonly appear. Thereafter viral infections can be observed more frequently. Cytomegalovirus infections are very dangerous in CMV-seronegative recipients with a lethality up to 90%. So a CMV-cross-match between the donor and recipient has to be performed. Transplant recipients have to be operated in aseptic conditions, with perioperative antibiotic prophylaxis. Regular serological analysis from blood and urine specimen has to be done to control bacterial, fungal and viral status, as well as regular monitoring of immunosuppressive regimen.

Bacterial Infections↗