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Biomedical subjects

E Wolner

Publications and source records attributed to E Wolner.

At least 235 records · Page 13Linked to original sources
PubMed1993

[Valve saving correction of aneurysms of the ascending aorta with aortic insufficiency or annular dilatation].

The current technique to correct aneurysms of the ascending aorta with incompetence of the aortic valve or dilatation of the aortic root is the implantation of a valved conduit. In many cases however structurally normal aortic leaflets are resected by this technique and patients are at the risk of complications due to mechanical heart valve prostheses and the necessary anticoagulation respectively. By resuspension of the aortic valve into the aortic prostheses similar to the technique used at implantation of homograft valves, competence of the valve can be restored and the dilatation of the aortic annulus can be prevented or even reduced. Our article describes the successful, valve sparing correction of an acute aortic dissection type A with dilatation of the aortic annulus in a 43 year old patient and in another patient with ascending aortic aneurysm with aortic insufficiency.

Adult↗
PubMed1993

Anomalous origin of the left coronary artery: a review of surgical management in 13 patients.

Over the last decades, surgical management of anomalous left coronary artery originating from the pulmonary artery (ALCAPA) has seen a considerable evolution. Between 1965 and 1992, 13 children with age at operation ranging between 2 months and 11 years (mean 23 months) underwent one of 5 different surgical procedures: ligation (n = 3), direct aortic reimplantation (n = 7), subclavian (n = 1) or internal mammary (n = 1) artery anastomosis, or modified aortic implantation (Vigneswaran-procedure, n = 1). There were 3 early and one late deaths resulting in an overall mortality of 30.7%. Mortality was 66.7% in the ligation group, and 20% in the revascularization group (28.6% in the subgroup with direct aortic implantation). The one late death occurred 6 months after ligation. Follow-up ranges between 3 months and 21 years, mean 7.3 years. All but one survivors are in NYHA functional class I. Following operative correction, there was clear improvement in left ventricular performance. Our data give reason to suggest ALCAPA to be more frequent than considered so far. Early surgery is recommended in all patients with ALCAPA, regardless of age or symptomatic status. Reestablishment of a two-coronary system is considered the procedure of choice. All survivors require long-term follow-up controls of early recognition of residual or progressive cardiac problems.

Austria↗
PubMed1993

Minimization of hemolysis in centrifugal blood pumps: influence of different geometries.

Centrifugal blood pumps are of substantial importance for intraoperative extracorporeal circulation and for temporary cardiac assist. Their development and improvement raises many specific questions, especially on mechanical blood properties, flow distribution, and the resulting biocompatibility. In this comprehensive study the influence of various pump geometries on blood trauma was investigated. For this purpose analytical calculations, hydrodynamic performance, numerical simulation, in vitro hemolysis tests and in vivo experiments were used. The gap between rotor and housing was found to be crucial showing a distinct minimum of hemolysis at a gap of 1.5 mm (in vitro increase of plasma free hemoglobin per 100 ml plasma an hour: delta fHb/hour = 2.4 +/- 0.83 mg%/h at 1.5 mm versus 12 +/- 2.2 mg%/h at 2.5 mm; p < 0.05). Housing diameter and shape of the vanes were of less importance for blood traumatization (d = 60 mm: delta fHb/hour = 6.36 +/- 1.8 mg%/h; d = 70 mm: fHb = 7.1 +/- 1.9 mg%/h; straight radial vanes: 5.2 +/- 1.8 mg%/h; straight inclined vanes: 6.8 +/- 1.2 mg%/h; flexed vanes: 6.1 +/- 2.0 mg%/h). Three animal experiments confirmed the optimization of geometry, with a mean fHb of 2.5 to 3.2 mg% in steady state. Hydrodynamic efficiency revealed to be a necessary, but not a sufficient and sensitive criterion for hemolysis minimization (e.g. changes of eta < 10% for changes of fHb > 500%). Numerical simulation gives an improved insight in flow distribution, but can not yet be applied for quantification of blood trauma.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Aneurysma spurium after iatrogenic arterial puncture--incidence, risk factors and surgical therapy].

Due to the markedly increased number of arterial punctures performed during diagnostic angiography and angioplasty procedures for cardiac and peripheral vessel disease, the complication of false aneurysms after arterial puncture has gained increasing significance. The incidence of false aneurysms after puncture reported in the literature ranges from 0.05-2%. However, careful sonographic follow-up may reveal an incidence twice as high. The goal of this retrospective investigation of 28 patients with false aneurysms was to elucidate risk factors leading to failure of spontaneous closure of the arterial site, as well as to examine the symptoms and clinical course of such patients. Pseudoaneurysms became manifest, depending on the method of puncture, on average 16.4 days after the procedure. The highest risk was seen in adipose patients (18 pts., 64.3%). In these patients the number of tangential and multiple vessel punctures was also highest. Further risk factors were local vessel sclerosis, hypertension, diabetes mellitus, poor general condition, and disturbances of blood coagulation. The typical clinical findings were seen in only 13 patients. In 3 patients blood loss was the predominant symptom. Twelve further pseudoaneurysms (42.8%) were found incidentally at follow-up. The diagnosis was made in all patients sonographically. In 1 patient it was initially identified as an incidental finding at angiography. In 25 cases simple vessel reconstruction was possible (stitch or patch). In 3 cases (10.7%) a more extensive procedure involving vessel replacement was necessary. Severe postoperative complications included local infection (in 2 patients, 1 of whom also had a recurrent false aneurysm) and arterial bleeding necessitating surgical intervention (1 patient).(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm, False↗
PubMed1993

Clinical and experimental results as a basis of 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 influence surgery in the near future. Minimal invasive and interventional techniques have already started to revolutionize surgical practice. So surgical research today combines traditional medicine and modern techniques to put into practice immediately. If surgeons consider their field to be a unity of "craftsmanship, art and science" [10] and at the same time adhere to the rules of ethics, they will comply with the principle of "saluti et solatio aegrorum".

Austria↗
PubMed1992

Mesh tube--constricted varicose veins used as bypass grafts for infrainguinal arterial reconstruction.

Varicose veins are generally deemed inappropriate graft material for arterial reconstructions despite their physiologic flow surface because of their large and irregular caliber. Size reduction by threading such veins in constricting tubes may create bypass grafts of suitable caliber as long as redundant wall material does not cause stenoses. Sixteen human varicose veins (mean +/- SD, 13 +/- 3 mm diameter) obtained after stripping operations were inserted into Dacron mesh tubes of 6 mm internal diameter. Paraffin casts of the distended veins showed a size reduction of 6.9 +/- 2.6 mm. Wall material formed folds in only two veins. In both cases, diameter reduction was more than 10 mm. However, the folds did not result in significant stenoses. Mesh-constricted varicose veins were used as bypass material in 11 infrainguinal arterial reconstructions. All externally supported segments showed satisfactory size reduction without stenoses or folds. One graft occluded 2 months after surgery. Two patients had to undergo reoperation after 2 and 16 months, respectively. None of the complications could be attributed to the constriction of veins. The remaining grafts are patent and functional after a mean of 17 months (range, 6 to 42 months). Considerable size reduction by external wrapping of varicose veins is possible without adverse side effects. Such constricted veins were used successfully as bypass grafts for infrainguinal arterial reconstructions.

Aged↗
PubMed1992

Management of severe bronchial ischemia after bilateral sequential lung transplantation.

A case of severe diffuse bronchial ischemia after bilateral sequential lung transplantation is presented. A combination of initial conservative treatment with silicone stenting and late bilateral retransplantation under stable conditions resulted in good clinical outcome. Factors in decision making and technical aspects of the stenting procedure are discussed.

Adult↗
PubMed1992

Noninvasive monitoring of rotary blood pumps: necessity, possibilities, and limitations.

Although rotary blood pumps do not contain an inherent mechanism for adaptation to physiological flow necessities, hitherto only a few efforts have been made to obtain robust monitoring and control methods. This paper discusses the necessity of noninvasive monitoring of such pumps and the crucial points of sensor selection and development. A strategy of monitoring atrial pressure out of the data obtained by the collapse of the atrial wall around the inflow cannula and initial results on animal tests and computer simulation of this method are discussed. This approach might lead to reliable and demand-responsive controllers, if some basic criteria are fulfilled.

Atrial Function↗
PubMed1992

Doppler sonographic evaluation of the CarboMedics bileaflet valve prosthesis: one-year experience.

Between April 1989 and March 1991, 237 CarboMedics bileaflet valve prosthesis carriers (165 aortic and 72 mitral valves, mean age 54.4 years) were studied prospectively with pulsed- and continuous-wave Doppler at a mean interval of 11.4 months following surgery in order to establish ranges of normal flow velocities and pressure gradients. Physical examination revealed no signs of prosthetic dysfunction or heart failure. Postoperative left ventricular function as measured by fractional shortening was 37% for aortic valve carriers and 30% for mitral valve carriers (p = NS). Mean peak velocity (+/- SD) across the aortic valve was 2.6 m/sec (+/- 0.4) and calculated instantaneous peak pressure gradient ranged from 11 to 58 mmHg (mean 28.1 +/- 10.3). It has to be emphasized that occasional patients with normally functioning valve prostheses can show unusual high gradients. Ring diameters between 21 and 27 mm showed no significant difference with regard to flow velocities and pressure gradients, whereas in 19-mm valves, significantly higher values could be demonstrated. The 123 aortic valve carriers with normal left ventricular function (fractional shortening greater than 25%) showed significantly higher pressure gradients than the 19 patients with reduced left ventricular function (28.6 +/- 11.6 mmHg vs 16.2 +/- 5.1 mmHg, p less than 0.05). In the mitral position, the mean of peak velocity (+/- SD) was 1.7 +/- 0.4 m/sec and pressure half-time was 108 +/- 26 msec, representing a calculated valve area between 1.4 to 3.1 cm2 (mean orifice size 2.1 +/- 0.5 cm2). No significant difference between valves of different sizes was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1992

Improved biocompatibility of bioprosthetic heart valves by L-glutamic acid treatment.

Treatment of glutaraldehyde-fixed pericardium with L-glutamic acid and storage in bacteriostatic preservatives (paraben) stably antagonizes free, reactive aldehyde groups within the fixed bioprosthetic heart valve tissue. In 63-day subcutaneous implants in rats, the calcification rate of this treatment (13.3 +/- 2 mg calcium/g wt tissue) was markedly reduced as compared to conventionally treated tissue (169 +/- 24 mg/g; p less than 0.05). To test the influence of tissue-released toxic aldehydes on spontaneous endothelial cell ingrowth in vivo, vascular grafts (8-cm long, 6-mm diameter) from fixed pericardium treated with L-glutamic acid were interposed into the carotid arteries in ten sheep. They were compared to grafts from conventionally treated pericardium implanted at the contralateral side. Following 3 months of implantation, planimetry revealed 49% +/- 20% of the surface of conventionally preserved pericardium to be covered with red thrombus, but only 12% +/- 5% in L-glutamic acid treated pericardium (p less than 0.05). The ultrastructural findings of a closed endothelial cell layer on the graft surface reveals the new technique to be a promising approach towards increased biocompatibility of aldehyde-fixed bioprosthetic heart valves.

Animals↗
PubMed1992

Endothelial cell lining of bioprosthetic heart valve material.

In this in vitro study, the growth properties of cultured endothelial cells on conventionally treated pericardial valve material were measured. These data were compared to endothelial cell proliferation on an alternatively treated valve material. This alternative preservation procedure was developed in order to bind free, residual glutaraldehyde in the valve tissue by reaction with L-glutamic acid. In order to optimize endothelial cell attachment and proliferation, fibronectin and fibrillar collagen type I were tested as surface precoating substances. Cell viability of the seeded cells was evaluated by means of proliferation kinetics, antithrombotic activity, and morphological appearance. Endothelial cell death occurred within the first 2 days after seeding on conventionally treated valve tissue, independent of the type of precoating. On alternatively treated tissue, regular endothelial cell proliferation was observed. Precoating with fibrillar collagen markedly increased endothelial cell attachment and proliferation as compared to fibronectin. Maintenance of antithrombotic activity of the seeded cells was proven by regular release of prostacyclin.

Animals↗
PubMed1992

One and one-half year experience with unilateral and bilateral lung transplantation.

Lung transplantation has now become an established form of treatment for end-stage pulmonary parenchymal and vascular diseases. Despite its wide acceptance, technical aspects are still in discussion. We report on the initiation of our own lung transplant program and the technical changes we have performed during our first 1 1/2-year experience. During that period of time, we have performed 26 lung transplantations (16 single lung [SLTX] and 10 bilateral lung transplantations [BLTX]). Three-month survival for the whole group was 74% (69% for the SLTX group and 77% for the BLTX group). No instance of bronchial dehiscence was observed; however, there were eight cases of bronchial stenosis: six were managed by silicone stent insertion, one by bronchoplastic correction, and one by retransplantation. Changes in the technique of the bronchial anastomosis together with the addition of prednisone to the immediate postoperative immunosuppressive regime resulted in almost complete avoidance of these problems.

Adult↗
PubMed1992

Closing sounds and related complaints after heart valve replacement with St Jude Medical, Duromedics Edwards, Björk-Shiley Monostrut, and Carbomedics prostheses.

OBJECTIVE: To measure the noise produced and related subjective complaints after implantation of four different mechanical heart valve prostheses and to identify further factors related to the patient and prosthesis that influence noise generation and complaints. DESIGN: Sound pressure was measured 5 and 10 cm and 1 m from the point of maximal impulse on the body surface by a calibrated meter in quiet rooms with either a decibel(A) filter or octave filters. The patients were asked about their complaints and examined physically. SETTING: The measurements were conducted in silent rooms of ear, nose, and throat departments. The patients had been operated on either in a university hospital or a community hospital. MAIN OUTCOME MEASURES: Sound pressures of frequency bands and sound pressures measured in dB(A) at various distances. Complaints registerd were: sleep disturbance, disturbance during daytime, "wants a less noisy prosthesis," and "can hear the closing click". PATIENTS: 143 patients after heart valve replacement with St Jude Medical (n = 35), Duromedics Edwards (n = 38), Carbomedics (n = 34) and Björk-Shiley Monostrut (n = 36) prostheses operated on between 1984 and 1988 were matched for valve position, ring size, and body surface area. RESULTS: Duromedics Edwards (33.5 (6) dB(A)) and Björk-Shiley Monostrut valves (31 (4) dB(A)) were significantly louder than St Jude Medical (24 (4) dB(A)) and Carbomedics (25 (6) dB(A)) prostheses (p = 0.0001) (mean (SD)). The louder valves were significantly more often heard by the patients (p = 0.0012) and caused more complaints both during sleep (p = 0.024) and during the daytime (p = 0.07). Patients with these valves were more likely to want a less noisy valve (p = 0.0047). Patients with symptoms were younger, had better hearing, and were more likely to be in sinus rhythm. As well as the type of prostheses, the valve diameter and body height also had an effect on sound emission. CONCLUSIONS: The intensity of the closing click of mechanical valve prostheses was significantly different for various designs. Patient complaints were related to the objectively measured sound pressure. Noise production should be considered when a mechanical valve is selected.

Adult↗
PubMed1992

[The coronary sinus as a source of activated T-lymphocytes in patients after orthotopic heart transplantation].

Mononuclear cells are the component of blood responsible for allograft recognition, rejection and acceptance. Shifts in the patterns of various mononuclear cell subpopulations were often used as a diagnostic tool in detection of heart rejection. The specificity of mononuclear cell monitoring has remained a controversial point until today, because infections led to similar changes as organ rejection. In this study we investigated whether mononuclear cells taken from coronary sinus blood give more information about the immunological status of the transplanted heart than those taken from central verous blood. After endomyocardial biopsy, coronary sinus blood was sampled by catheterization under X-ray control. Blood from the right atrium was taken for control measurement. Mononuclear cells obtained by density gradient cytocentrifugation were stained with monoclonal fluorescein conjugated antibodies detecting CD4- (T helper)-, CD8- (T suppressor)-, CD25- (Interleukin-2 receptor), and the CD71- (Transferrin receptor) antigens. Endomyocardial biopsies were graded according to the Billingham scheme. In the absence of rejection, the phenotypes of mononuclear cells from the coronary sinus did not differ from those of right atrial cells. Mild rejection led to a statistically insignificant increase of CD4- CD25- and CD7-antigen bearing cells in the coronary sinus blood, whereas the CD8 positive cells remained stable as compared to mononuclear cells from the right atrium. However, patients with moderate rejection showed a significant elevation of CD4 positive cells and activated T-cells (CD15-, CD71-positive cells) in the coronary sinus as compared with cells from the right atrium. The T helper/suppressor ratio (Th/s-ratio) shifted towards the T-helper population.(ABSTRACT TRUNCATED AT 250 WORDS)

CD4-CD8 Ratio↗
PubMed1992

Endothelial cell lining of bioprosthetic heart valve materials.

To investigate the conditions for endothelial cell lining of glutaraldehyde-treated bioprosthetic heart valves, we examined in vitro the growth properties of endothelial cells on clinically used pericardial valve material and on glutaraldehyde-fixed pericardium treated with L-glutamic acid. To improve endothelial cell attachment to the valvular surface, we precoated both materials either with fibronectin or with fibrillar collagen (95% type I, 5% type III). Toxicity of glutaraldehyde, released from clinically used valve material, caused endothelial cell death, independent of the type of precoating. Treatment of the valve material with L-glutamic acid resulted in regular endothelial cell proliferation. We found that collagenous precoating, compared with fibronectin precoating, markedly enhanced endothelial cell proliferation and attachment (p less than 0.05). Maintenance of antithrombogenic potency of the seeded cells on L-glutamic acid-treated valve material was proved by regular release of prostacyclin. We conclude that bioprosthetic heart valve materials can be lined with endothelial cells if toxic glutaraldehyde released from the bioprostheses is eliminated.

Animals↗
PubMed1992

Aprotinin decreases release of 6-keto-prostaglandin F1 alpha and increases release of thromboxane B2 in cultured human umbilical vein endothelial cells.

Use of the proteinase inhibitor aprotinin significantly improves hemostasis and reduces bleeding after operations in which extracorporeal circulation is used. The mechanism of action, however, has been only partially clarified. In this work we investigated whether aprotinin influenced the production and release of the eicosanoids prostacyclin, measured as the stable metabolite 6-keto-prostaglandin F1 alpha, and thromboxane A2, measured as the stable metabolite thromboxane B2, from endothelial cells. Human umbilical vein endothelial cells were incubated with different concentrations of aprotinin (5.5, 20, 55, and 100 mumol/L). The levels of 6-keto-prostaglandin F1 alpha and thromboxane B2 were measured at baseline and after thrombin stimulation. A concentration-dependent effect of aprotinin on 6-keto-prostaglandin F1 alpha synthesis was demonstrated. After incubation with 100 mumol/L of aprotinin, a 90% reduction in 6-keto-prostaglandin F1 alpha production was seen (31.69 versus 307.44 picograms per million cells; p less than 0.001). Conversely, thromboxane B2 production showed a 345% increase after incubation with aprotinin (287.80 versus 83.82 picograms per million cells; p less than 0.0001). Since 6-keto-prostaglandin F1 alpha inhibits and thromboxane B2 strongly enhances platelet aggregation, it appears that one mechanism of the clinically observed effectiveness of aprotinin lies in the altered ratio of 6-keto-prostaglandin F1 alpha: thromboxane B2 in endothelial cells, which leads to enhanced platelet aggregation and improved vessel sealing.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Implantation of in vitro endothelialized polytetrafluoroethylene grafts in human beings. A preliminary report.

To assess the impact of in vitro endothelialization on prosthetic graft patency, we performed femorotibial reconstruction in four patients. Polytetrafluoroethylene grafts (6 mm), lined with cultivated autologous endothelial cells, harvested from the veins of the forearm, were used. Autologous endothelial cells were harvested enzymatically and characterized by morphology and factor VII staining. After a cultivation period of 17 to 23 days, the cell count increased from 27 +/- 3 x 10(4) endothelial cells to 5.4 +/- 1.1 x 10(6). Endothelial cell seeding on polytetrafluoroethylene prostheses was then performed. To improve endothelial cell attachment to the graft surface, polytetrafluoroethylene grafts (60 to 70 cm; 6 mm diameter) were precoated with fibrin glue containing fibrin and fibronectin and the fibrinolysis inhibitor aprotinin. Seeding density of 49 +/- 10 x 10(3) endothelial cells per square centimeter yielded a preconfluent monolayer immediately after seeding, as demonstrated by scanning electron microscopy. A second cultivation period of 6 days, after seeding and before implantation, was necessary for establishment of a confluent monolayer and to allow for maturation of the endothelial cell cytoskeleton as well as production and excretion of extracellular matrix. Grafts endothelialized in vitro were implanted in four patients requiring femorotibial reconstruction. Scintigraphic studies with indium 111-labeled platelets demonstrated little or no platelet deposition, indicating persistent endothelialization. All grafts remained patent at 3 months after implantation.

Aged↗