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Biomedical subjects

E Wolner

Publications and source records attributed to E Wolner.

At least 271 records · Page 15Linked to original sources
PubMed1991

Improved spontaneous endothelialization by postfixation treatment of bovine pericardium.

The longstanding release of locally cytotoxic glutaraldehyde concentrations from fixed biological materials is one reason for the lack of spontaneous endothelialization in vivo and in vitro of biological grafts (and valves). Preliminary studies have shown that bovine pericardium postfixation-treated with aminoacids may be endothelialized in vitro. To test whether such treatment improves spontaneous endothelialization in vivo 8 cm long segments grafts (6 mm I.D.) were interposed into the carotid arteries of 10 sheep. Ten grafts were sewn from postfixation treated pericardium (PTP), 4 from standard glutaraldehyde fixed pericardium (GAP) and 6 polytetrafluoroethylane (PTFE) grafts were implanted to study the degree of spontaneous endothelialization. In two pregnant animals, all grafts occluded (2 PTP, 1 GAP, 1 PTFE). In the remaining animals 1 additional PTFE graft occluded and 2 PTFE and 1 GA grafts showed significant thrombotic obstruction. The patent grafts were harvested at 3 months and the surface covered with red thrombus was determined by planimetry. PTP grafts had significantly less (12.2% +/- 15%) thrombotic appositions than glutaraldehyde treated grafts (49% +/- 20%; P = 0.01) and PTFE grafts (40.5% +/- 13%; P = 0.01). In the central areas of the PTP grafts, endothelial cells spread directly on the collagenous matrix and produced a basal lamina. In GAP, endothelial cells spread on amorphous material or macrophages and in PTFE grafts, only a neointima composed of myofibroblasts was endothelialized. Neutralization of glutaraldehyde concentrations by postfixation with aminoacids improves spontaneous endothelialization in vivo in biological materials.

Animals↗
PubMed1991

Prosthetic bypass and flow reversal in the dissecting thoraco-abdominal aortic aneurysm.

In 1981 Carpentier and Co-workers introduced an alternative surgical procedure for great dissecting thoraco-abdominal aortic aneurysms, departing from the resection and the orthotopic implantation of a prosthesis (graft inclusion technique). Compression of the aneurysmatic false lumen from the inside under stepwise thrombosis of the aneurysmal sac with conservation of the main arterial origins was achieved by prosthetic bypass of the diseased vascular part and a flow reversal in the dissected aortic region by an oblique suture across the aortic lumen after the origin of the left subclavian artery. This procedure, distinguished by rather little effort and few complications (bleeding, ischaemic spinal cord damage) is described for all stages of dissecting thoracal aortic aneurysms. In the last 2 years this operation was performed in our department on 4 patients (1 m. 3 f) suffering from an acute dissecting thoraco-abdominal aortic aneurysm (Stanford type B). 2 patients died in the early postoperative period, one from a redissection close to the proximal anastomosis, the other due to the critical cardiac situation. 2 patients could be followed up postoperatively 10 and 27 months. In both cases no signs of minor perfusion of the spinal cord, the kidneys, or the mesenterial organs were observed. In both cases a partial thrombosis of the aneurysmal sac with intact blood stream to the major vessels in these regions could be demonstrated by sonography, angiography or DSA, and computer tomography. The concept of flow reversal proved to be an alternative to major resection procedures.

Aged↗
PubMed1991

Immediate effects of mammary artery revascularization versus saphenous vein on global and regional myocardial function: an intraoperative echocardiographic assessment.

The immediate effect of coronary artery bypass surgery on global and regional myocardial function using the internal mammary artery (IMA) versus saphenous vein (SV) was studied intraoperatively using transesophageal echocardiography (TEE). Thirty-two patients received an IMA and 10 patients only SV. Transesophageal echocardiography was recorded before thoracotomy, 5 minutes after the end of cardiopulmonary bypass (CPB) and after chest closure. Global and regional left ventricular function were expressed as a percent of the short axis area change (%SAAC) and a percent of the fractional area change (%FAC), respectively. Segments were classified according to their baseline function as normal, %FAC greater than 40%, or dysfunctional, %FAC less than 40%. Only normal segments were considered in this study. No significant change in %SAAC in either group was observed in this study. Internal mammary artery revascularized segments showed a significant decrease in %FAC from 57 +/- 1 before thoractomy to 53 +/- 2 5 minutes after CPB, whereas SV segments showed a significant improvement in %FAC from 56 +/- 1 to 61 +/- 1. Applying strict criteria derived from intraobserver and cycle-to-cycle variability, 17% of IMA segments had deteriorated by more than 36% whereas only 4% of SV segments showed such deterioration. Conversely, 17% of SV segments showed an increase in %FAC by more than 36% and only 3% of IMA segments improved similarily. The observed changes were of short duration and had largely resolved by chest closure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

The progression of mild acute cardiac rejection evaluated by risk factor analysis. The impact of maintenance steroids and serum creatinine.

The natural course of mild acute cardiac allograft rejection (MAR) under cyclosporine-based therapy is generally considered benign, and usually antirejection therapy is not instituted. The present study was undertaken to determine the frequency of and the risk factors for progression of MAR into a clinically significant (moderate or severe) rejection on subsequent endomyocardial biopsy (EMB). Among 167 cardiac recipients, transplanted from 3/1984 to 4/1990, MAR under cyclosporine-based therapy was diagnosed on 220 EMBs. Depending upon the outcome on the subsequent EMB, MAR was categorized as progressive or nonprogressive. This served as the dependent variable for a stepwise logistic regression analysis evaluating 11 covariates as potential risk factors: perioperative antibody prophylaxis (ATG vs. OKT3), maintenance therapy, underlying disease, HLA-mismatches for A- and B + DR-loci, serum creatinine (mg/dl) and cyclosporine HPLC blood level (ng/ml) at diagnosis of MAR and at subsequent biopsy, recipient age, donor age. 40 (18.2%) of 220 MARs became progressive as opposed to 37 (7.3%) of a control cohort of 507 negative EMBs (P less than 0.0001). Stepwise logistic regression yielded the type of maintenance therapy (P = 0.0019) and serum creatinine level at diagnosis of MAR (P = 0.0615) as independent predictors of progression of MAR. After adjustment for influence of maintenance therapy and serum creatinine none of the cyclosporine variables provided any additional information. MARs without maintenance steroids and low serum creatinine levels had the highest risk (37.2% observed incidence) to develop moderate or severe rejection on subsequent EMB. This analysis supports evidence that diagnosis of MAR on EMB is associated with a considerable high progression rate into clinically significant rejection when compared to negative EMBs. Progression particularly occurs in MAR under steroid-free maintenance therapy and suggests early augmentation of immunosuppression. In terms of progression of MAR serum creatinine values, obviously indicating cyclosporine nephrotoxicity, appear to reflect the extent of cyclosporine-mediated immunosuppressive activity more properly than parameters of its bioavailability by measuring cyclosporine HPLC blood levels.

Adrenal Cortex Hormones↗
PubMed1991

The new small Viennese total artificial heart: experimental and first clinical experiences.

For bridging to transplantation, a new small total artificial heart (TAH) design has been developed. Function of the two membrane pumps (filling volume left: 87 ml, and right: 75 ml; four mechanical disc valves and screwed connectors) for orthotopic implantation were studied in calf experiments. A calf survival up to 180 days was achieved without problems by pumping with a rate of 117 +/- 2.4 beats/min and a cardiac output of 7.4 +/- 0.7 L/min. For bridging to transplantation, the New Small Viennese TAH was implanted into a small 45-year-old patient (height 160 cm, weight 75 kg) with end-stage coronary heart disease. The patient deteriorated suddenly [mean aortic pressure: 38 mm Hg; cardiac output (CO): 1.8-2.1 L/min; anuria and multiple organ failure] while waiting for a donor heart. Even though his pericardial space was not enlarged, no fitting problems appeared. By using pumping rates of 104.3 +/- 8.7 beats/min, a cardiac output of 5.8 +/- 0.63 L/min was achieved (free hemoglobin was 4.1 +/- 0.48 mg/dl). Even though blood circulation was reestablished, after a TAH duration of 12 days, multiple organ failure persisted, and TAH bridging had to be stopped. In November 1989, a 50-year-old deteriorating transplant candidate with idiopathic cardiomyopathy was bridged for 6 days. Adjusting the heart rate to 86.5 +/- 11.2 beats/min, a CO of 6.84 +/- 0.46 L/min was achieved (free hemoglobin was 5.9 +/- 1.7 mg/dl). Because of chronic liver dysfunction, the patient developed severe icterus while on the TAH, and it took 2 months after heart transplantation to achieve physiological bilirubin concentrations. The patient recovered fully and remains in excellent condition.

Animals↗
PubMed1991

Biocompatibility of aldehyde-fixed bovine pericardium. An in vitro and in vivo approach toward improvement of bioprosthetic heart valves.

Aldehyde-induced side effects limit the clinical usefulness of bioprosthetic heart valves. Treatment of aldehyde-fixed pericardium with L-glutamic acid at pH 3.5 and storage in a nontoxic, bacteriostatic solution resulted in a lower degree of calcification in 63-day subcutaneous implants in rats (13.3 +/- 2 mg calcium per gram dry weight of tissue), as compared with commercially available tissue (169 +/- 24 mg/gm, p less than 0.05). Endothelial cells died within 1 day after seeding on the commercial tissue; however, considerable endothelial cell proliferation was measured, even 14 days after seeding on L-glutamic acid-treated pericardium. Improved biocompatibility of this alternative treatment may be due to stable chemical binding of free, reactive aldehyde groups.

Animals↗
PubMed1991

[The value of clinical and experimental results for surgical practice].

Since John Hunter first applied the scientific approach to surgery in the late 18th century, it has been raised from the humble level of a handicraft to a highly experimental science. Although surgical research is essential, the practice of surgery has always been much influenced by the basic sciences. The clinical significance of experimental data has often only been recognized years later: research to no pre-defined end is also of utmost importance. Today in a time of cost explosion and overabundance of information cooperative and statistically well-planned studies are essential to optimize financial and physical resources. Fields of increasing interest such as gene technology, immunology and preventive medicine will certainly influence surgery in the near future. Minimal invasive and interventional techniques have already started to revolutionize surgical practice.

Austria↗
PubMed1991

[Uni- and bilateral lung transplantation: surgical results and experiences of the 1st year. Vienna Lung Transplant Group].

Transplantation of the lung has gained increasing importance during the last years and is now an established therapy for end stage lung disease. After a 3 years period of preparation the first single lung transplantation (SLTX) was performed at the Second Surgical Department of the University of Vienna in November 1989, followed by the first double lung transplantation (DLTX) in April 1990. Until the end of 1990 11 patients underwent SLTX and 6 DLTX. 7 of the 11 SLTX patients and 4 of the 6 DLTX patients are at present alive with significantly improved lung function and therefore markedly improved quality of life.

Adult↗
PubMed1991

Mesh-constricted varicose and dilated veins used as arterial bypass grafts.

To avoid non-autogenous vascular prostheses in coronary and peripheral vascular procedures, otherwise unusable dilated, varicose or thin-walled veins can be implanted as naturally endothelialized grafts after being calibrated by insertion into mesh tubes. In six sheep the 14 mm diameter jugular vein was inserted into a 12 cm long, 6 mm diameter Dacron mesh tube and implanted as a femoropopliteal graft. On the contralateral side the femoral vein with a maximal diameter of 7 to 8 mm was implanted. At control angiography after two months all grafts were patent, none of the wrapped grafts showed wrinkles or signs of anastomotic hyperplasia. Segments of wrapped veins were casted in paraffin under physiological pressure and cut transversely. In all cases the vein wall was pressed against the mesh tubes without forming folds. Mesh-wrapped varicose veins were used for three femorocrural and seven femoropopliteal reconstructions. All grafts showed a smooth flow surface at control angiography. Indentations occurred only at sites where thick-walled side branches had been ligated rather than oversewn. One popliteo-pedal reconstruction occluded after two months and one patient with a crural reconstruction died two months after surgery with a patent graft. The remaining grafts were patent after 11 (2-32) months. Oversized veins can be considerably constricted by tubes without forming wrinkles. By this technique varicose veins can be used as bypass grafts and in general vein grafts can be matched in size to the recipient vessel.

Aged↗
PubMed1991

[Complicated course of a compression syndrome of the popliteal artery in a 36-year-old patient].

The popliteal entrapment syndrome is an entity increasingly reported over the past few years. Anatomical variations should be considered if a localized stenosis or occlusion of the popliteal artery is diagnosed in a young, otherwise healthy individual. This case report documents a complicated course of the disease in a young man in whom diagnosis was made only after futile attempts of intraarterial lysis and dilatation at the time of a second operation. A complex crural reconstruction was necessary in order to revascularize the treatment limb.

Adult↗
PubMed1991

[Unilateral lung transplantation as an effective therapy in primary lung emphysema].

Unilateral lung transplantation is the treatment of choice for terminal restrictive lung disease. We report about three patients with end-stage pulmonary emphysema treated by single lung transplantation. All patients are alive 3, 6 and 7 months after the operation with good quality of life. Blood gases have normalized and lung function parameters have markedly improved. We conclude, that single lung transplantation can be an effective treatment for selected patients with end-stage obstructive lung diseases in the absence of chronic infections.

Adult↗
PubMed1991

Closing click of St Jude Medical and Duromedics Edwards bileaflet valves: complaints created by valve noise and their relation to sound pressure and hearing level.

The metallic clicking sound created by mechanical heart valve prostheses frequently bothers patients. To test whether sounds generated by different bileaflet valves correlate to complaints related to the prosthetic clicking 73 patients were investigated after valve replacement with Duromedics Edwards (DE) (n = 38) and St Jude Medical (SJM) (n = 35) valves. The patients were asked about their complaints, sound pressure levels were recorded and audiometry was performed. Sixty-five percent of patients could hear their valve, 18% had sleeping disturbances, 5% felt bothered during daytime and 12% would prefer a less noisy valve. In symptomatic patients, sound pressure levels were higher than in asymptomatic patients (valve audible 45 +/- 8 db(A) vs not audible 39.9 +/- 10 db(A) at 10 cm; P = 0.016). These differences were most apparent in the high frequency bands, corresponding to the metallic click. Symptomatic patients had better hearing and were younger than patients without complaints. Fifty-one percent could hear their valve by conduction through the body, after eliminating air conduction by the use of headsets. The DE prostheses were louder than the SJM valves in general (47.4 +/- 7 vs 39.8 +/- 5 db (A) at 10 cm; P = 0.001) and in each valve position. Patients with DE prostheses had significantly more complaints. The intensity of the closing click of mechanical valves correlates to the complaints caused by prosthetic clicking and thus sound emission should be considered when a mechanical heart valve prosthesis is selected.

Adult↗
PubMed1991

Timing for implantation and transplantation in mechanical bridge to transplantation.

The implantation of a mechanical blood pump in a deteriorating candidate for heart transplantation is indicated in general if the cardiac index is less than 1.9 L/min/m2 despite maximal inotropic support. Deterioration of end organ function may be taken as a second factor indicating the need for mechanical support as patients with acute onset of shock may react differently from patients with chronic deterioration. Preoperative need for dialysis largely reduces the chances of long-term survival. The time on support should be long enough to normalize or at least improve secondarily damaged organ systems, but with time infectious and thromboembolic complications will increase. So optimal periods for artificial heart support range between two days and four weeks. Age less than 40 years is a positive predictor for outcome in TAH bridging. The general guidelines, however, do not preclude a favourable outcome in complicated cases, as we show in our own series.

Adult↗
PubMed1991

Monitoring of mononuclear cell subsets isolated from the coronary sinus and the right atrium in patients after heart allograft transplantation.

The rejection of a transplanted heart leads to an accumulation of mononuclear cells in the cardiac tissue and to reactions of the antigen-recognizing cells with the foreign tissue. Consequently, during rejections immunologic changes, such as the number of mononuclear cells and the patterns of mononuclear cell subpopulations, should be detectable by analysis of mononuclear cells from the coronary sinus of transplanted hearts. Seventy-nine endomyocardial biopsies were performed in 37 patients. Severity of graft rejection was classified by the Billingham scheme. Thirty-two biopsy specimens showed no rejection, 33 mild, and 14 moderate rejection. After endomyocardial biopsy the coronary sinus was catheterized under x-ray guidance. Heparinized blood samples were obtained from the coronary sinus and the right atrium, and mononuclear cell counts and subpopulation pattern were compared. Patients without rejection and patients with mild rejection showed no significant differences in the patterns of mononuclear cell subpopulation identified in right atrium blood. However, a significant (1.56-fold) increase of mononuclear cells was assessed in the CS blood (p less than 0.01). Moderate rejections showed a 4.2-fold augmentation of mononuclear cells in the coronary sinus (p less than 0.005) compared with nonrejections. In addition, the T-helper/inducer (CD4) percentage increased from 27.1% in the right atrium to 41.2% in the coronary sinus (p less than 0.005), natural killer cells (CD16) from 17.7% to 31.8% (p less than 0.005), and the interleukin 2 receptor-bearing cells from 6.6% to 15.3% (p less than 0.005). Percentage of pan-T cells (CD3), T-cytotoxic/suppressor cells (CD8), and monocytes (CD14) showed no statistically significant changes. These findings correlated with grading according to endomyocardial biopsy. Using the ratio of values obtained from cells of the coronary sinus and the right atrium rendered the coronary sinus immunologic monitoring independent of changes in the administered immunosuppressive regimen. The specificity of the described method was as good as that of endomyocardial biopsy. It is concluded that the discrimination of the patterns of mononuclear cell subpopulations from right atrium versus coronary sinus blood samples is highly sensitive and allows the correct diagnosis of graft rejection within 1 to 2 hours.

Antigens, CD↗
PubMed1991

[Noise origin and noise-induced complaints after heart valve replacement with mechanical prostheses].

143 patients were investigated in order to determine whether there is a difference in the intensity of the closing click between different mechanical heart valve prostheses. 35 had St. Jude Medical (SJM), 38 Duromedics Edwards (DE), 36 Björk Shiley Monostrut (BSM) and 34 had Carbomedics prostheses implanted. Sound pressure level determined at 1 meter distance was significantly higher for the DE 33.5 +/- 6 dB(A) and BSM 31 +/- 4 dB(A) than for the SJM 24 +/- 4 dB(A) and CM 25 +/- 6 dB(A) prostheses (p = 0.0001). Valves developing higher sound pressures were more frequently audible for the patients (p = 0.0012), caused more sleep disturbances (p = 0.024) and more complaints during daytime (p = 0.07). Significantly more patients carrying such valves wished to have a less noisy valve implanted (0.0047). Symptomatic patients wear louder valves, were younger, had better hearing and were more frequently in sinus rhythm. Valve diameter correlated with the developed sound pressure level. 349 patients answered a questionnaire after valve replacement with DE (256) or BSM (93) prostheses. 5% registered their noise-related complaints as being severe, but more than one third wished to have a less noisy valve implanted. The noise created by the closing click of mechanical prostheses causes significant complaints and this factor should be considered when a mechanical valve is selected.

Adult↗
PubMed1991

[Results of transverse tracheal resection in post-intubation tracheal stenoses].

Tracheal problems in form of stenosis and malacia are a calculated risk of long-term tracheal intubation. Results with conservative treatment of such problems by bougienage, laser therapy, biopsy, cryotherapy, local steroids, tracheal stenting, and tracheostomy are not satisfactory in a higher percentage of cases. Resectional therapy of benign tracheal lesions has become an established technique, which combines excellent functional results with a low complication incidence. We have treated 40 patients of 17 to 76 years of age with postintubation tracheal lesions by cross resection of the affected segment. Of these patients 40% had received conservative therapeutical steps preoperatively. The mean resection length was 3.0 cm (1.5 to 6.5 cm). The perioperative morbidity was 7.8%, mortality was 2.5%. 85% of the patients operated between 1970 and 1989 were reached for a follow-up examination with x-ray, pulmonary function test and endoscopy. The patients subjective satisfaction with the operative result was good in 85%, minor in 12% and less in 3%. The objective investigations proved very good results in 90%. Our experience confirm the good results of other authors and recommend the resection treatment for cases of postintubation tracheal lesions.

Adolescent↗