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Biomedical subjects

E Wolner

Publications and source records attributed to E Wolner.

At least 253 records · Page 14Linked to original sources
PubMed1992

Aprotinin increases release of von Willebrand factor in cultured human umbilical vein endothelial cells.

Through the perioperative administration of the proteinase inhibitor aprotinin, hemostasis can be improved and postoperative bleeding reduced after cardiac operations. The mechanism of action has been only partially clarified. The goal of our study was to investigate the influence of aprotinin on the synthesis of von Willebrand factor (vWF) in human endothelial cells. Human umbilical vein endothelial cells (HUVEC) were cultivated in vitro and incubated with different aprotinin concentrations (55, 100, and 215 mol/L). With all investigated aprotinin concentrations, there was an increase in vWF synthesis compared with basal secretion (p less than 0.001). When the HUVEC were preincubated with aprotinin and stimulated with thrombin, there was a further significant increase in vWF synthesis. HUVEC that, were first incubated with aprotinin and then stimulated with thrombin demonstrated a significant increase in vWF synthesis compared with basal secretion in nonincubated cells (p less than 0.0001). Also, compared with the cells that had received thrombin stimulation alone, the combination of aprotinin incubation and thrombin stimulation led to a significantly higher vWF concentration (p less than 0.05). Because vWF is necessary for the interaction with platelet factor glycoprotein Ib and platelet adhesion, the demonstrated increase in vWF synthesis could be one of the mechanisms of action of aprotinin leading to its blood-sparing effect.

Aprotinin↗
PubMed1992

[Surgery of blunt heart trauma].

Between 1972 and 1990 11 patients--all but one of them with multiple injuries--were treated surgically for blunt cardiac trauma caused by traffic accident in about 90%. Myocardial rupture (n = 3), laceration of the pericardial sac (n = 1), mitral insufficiency (n = 5; one of them in combination with atrial septal defect), ventricular septal defect (n = 1) and myocardial aneurysm (n = 1) occurred. Patients with myocardial rupture and pericardial laceration died within 2 h after admission to hospital; the other patients were successfully treated by mitral valve replacement (n = 4), mitral valvuloplasty and repair of ASD, suture repair of VSD and resection of myocardial aneurysm in one case, respectively. The interval to operation was 8 months to 12 years. Whereas pericardial tamponade caused by rupture of the atrial or ventricular wall and injuries of main coronary vessels require immediate surgical intervention, valve insufficiencies, septal defects or myocardial aneurysms may be mostly treated at a later date. Improvement of logistic measurements and the suspicion of blunt cardiac trauma followed by immediate surgical intervention may reduce the mortality rate in cases of cardiac rupture.

Adolescent↗
PubMed1992

[Video-endoscopic interventions in thoracic surgery].

Between October and December 1991 we performed videoendoscopic procedures, including resection of lung tissue, on 9 patients in our thoracic surgery unit. A lung measuring 15 x 18 was extirpated in 1 patient and parietal pleurectomy was performed after complicated pneumothorax in 4 patients. In one of these cases it was necessary to close a parenchymal leak and in 3 cases bullae had to be removed. Resection was undertaken in 4 patients for peripheral lung nodules, in one of them for metastases. Two patients proceeded to conventional lobectomy immediately after the frozen section results came through. Closure of lung parenchyma was carried out by means of the new ENDO-GIA stapler. Duration of the procedure was less than one hour except in the case of one patient. In one case it was necessary to use three cannulae. In the other cases two cannulae (one for videoendoscopy and fixating instrument, one for preparation instrument and stapler) sufficed for the operation to be undertaken without difficulty. This new technique brings all the known advantages of minimal invasive intervention to patients requiring thoracic surgery.

Adult↗
PubMed1992

The determinants of elevated total plasma cholesterol levels in cardiac transplant recipients administered low dose cyclosporine for immunosuppression.

Elevated total plasma cholesterol level is a frequent finding after cardiac transplantation. To identify risk factors for the development of hypercholesterolemic states, we applied multivariate statistics in a logistic and linear manner. Six-month posttransplantation levels of total plasma cholesterol in 57 adult heart recipients were available for analysis. Maintenance immunosuppression was carried out with either cyclosporine and azathioprine or both agents plus low-dose steroids. Total plasma cholesterol levels were dichotomized for the logistic analysis (1) by the age- and sex-matched 75th and 90th percentiles of a reference population according to National Institutes of Health treatment guidelines and (2) by the cut point 250 mg/dl. Twelve potential risk factors were evaluated as covariates: recipient age, body weight after 6 months, body weight gain over 6 months, body mass index after 6 months, body mass index gain over 6 months, current cyclosporine dosage, trough level of cyclosporine in whole blood according to high-performance liquid chromatography after 6 months, cumulative cyclosporine dosage over 6 months, serum bilirubin, type of original cardiac disease, maintenance steroids, and steroid bolus treatment. Multivariate logistic regression yielded the type of original cardiac disease as a significant predictor of posttransplantation hypercholesterolemia exceeding the 90th percentile (p = 0.019) and of hypercholesterolemia exceeding 250 mg/dl (p = 0.032). Maintenance steroids were identified as a second significant cofactor (p = 0.069) for total plasma cholesterol levels exceeding 250 mg/dl. Multiple linear regression again revealed the type of original cardiac disease and maintenance steroids as significant predictors by p values of 0.005 and 0.013, respectively. Patients with coronary artery disease as the original cardiac pathology and low-dose maintenance steroids had the greatest risk for the development of elevated total plasma cholesterol levels after cardiac transplantation. However, the overall predictive quality of the linear model was limited (multiple r value 0.43), which indicates that other variables besides the tested ones attributed to elevated total plasma cholesterol levels. These results confirm the adverse role of maintenance steroids on posttransplantation hypercholesterolemia and demonstrate the type of original cardiac disease as the most important risk factor. They suggest that abnormalities of lipoprotein metabolism and dietary factors continue to affect total plasma cholesterol levels after cardiac transplantation.

Adult↗
PubMed1992

A modular mock circulation for hydromechanical studies on valves, stenoses, vascular grafts and cardiac assist devices.

P6vices for hydrodynamic simulation are required in a variety of studies such as device evaluation, cardiovascular modeling and for student training. Most studies today use different, incompatible circuits, which must be redesigned for every new application. To obtain a universal apparatus, a unitized system with standard connectors was developed. Three types of connectors were selected: 1" flange connectors, 1/2" tubing connectors and Luer-connectors with a 2 mm lumen. The complete system consists of reservoirs, throttles, valve holders, adapters for Doppler ultrasound probes, and converters to link these basic diameters. The apparatus can be driven by membrane, centrifugal and geared pumps. The system has successfully been used in echocardiographic studies of stenosis and valvular insufficiency, for pulse propagation in vascular grafts, and to test the hydraulic performance of cardiac assist devices. Flow rates between 0.1 and 30 l/min and pressure gradients up to 250 mmHg were achieved. In practical use, the system can be adapted to suit various investigations, with minimal expense. Standardization of the parts and connectors results in simple documentation and good reproducibility.

Blood Circulation↗
PubMed1992

Mechanical bridge to transplantation with the Vienna heart in TAH and LVAD configuration.

The Vienna heart uses a vacuum formed, pellethane pulsatile ventricle and is available in left ventricular assist (LVAD) and total artificial heart (TAH) configurations. This device was used as mechanical support of the failing heart in nine patients intended for heart transplantation. In two patients with cardiomyopathy an orthotopic TAH was implanted; one survived despite severe preoperative ischemic liver damage, and the other died of sepsis. In seven patients an atrio-aortic LVAD was implanted; six had suffered an acute myocardial infarction with cardiogenic shock, and one could not be weaned off bypass. Three patients survived. These included one 65-year-old with incipient ARDS at operation, and a 40-year-old with preoperative liver and kidney insufficiency who was transplanted in septicemia. In this patient the septic focus, natural and artificial heart, were removed at transplantation. Four patients died. In one we were unable to establish satisfactory circulation, one died after failure of the transplanted heart, one suffered a lethal cerebral embolism and one developed multi-organ failure after repeated attacks of ventricular fibrillation. With the Vienna heart sufficient circulatory support could be established with cardiac outputs between 6 and 8 l/min for the TAH and 3.5 to 4.5 l/min for the LVAD. With this type of support an overall survival rate of 44% could be achieved. Mechanical hemolysis was not a clinical problem and no device failure occurred.

Cardiomyopathies↗
PubMed1992

Prospective clinical study with in vitro endothelial cell lining of expanded polytetrafluoroethylene grafts in crural repeat reconstruction.

A nonrandomized prospective clinical study was undertaken to evaluate the technique and efficacy of in vitro endothelial cell lining of synthetic grafts. Twenty-six patients (10 men and 16 women with a mean age of 68.4 years; range, 49 to 80 years) with end stage chronic peripheral vascular disease requiring reoperation were entered into the study. In 13 patients venous endothelial cells were harvested 4 to 7 weeks before operation, grown to confluency in culture flasks, and seeded onto the inner surface of expanded polytetrafluoroethylene grafts. Thirteen patients received untreated expanded polytetrafluoroethylene grafts and served as a control. A scoring system with use of intraarterial angiography was used to assess disease severity. No statistically significant differences in angiographic score were seen between the two groups, indicating comparable severity of disease. Early secondary graft patency (0 to 30 days) was 92% for the in vitro endothelial cell lining group and 53% for control patients. The amputation rate after 18 months for the in vitro endothelial cell lining group was 15%, with a 31% rate in the control group. The functional performance of the in vitro endothelial cell lining bypasses was superior to that of untreated bypass grafts during the observed follow-up period. These early results suggest that in vitro endothelial cell lining is a method that can reduce the early occlusion rate now seen after repeat reconstruction of crural vessels.

Aged↗
PubMed1992

Transesophageal echocardiography in the emergency surgical management of patients with aortic dissection.

The diagnostic accuracy and benefit of transesophageal echocardiography were investigated in 32 patients with suspected aortic dissection. Results of transesophageal echocardiography were compared with surgical assessment. The Stanford classification was used for differentiation of dissection type. Examination time was 5 to 15 minutes. Twenty-eight patients were correctly identified to have aortic dissection; four patients had nondissecting aneurysms of the ascending aorta. Both sensitivity and specificity for detection of aortic dissection were 100%. Type of dissection was misdiagnosed in one patient. Classification of dissection type was correct in 96%. The primary entry site was correctly identified in 25 patients (89%). Aortic regurgitation was found in 57% of patients. Pericardial effusion was detected in 21%, with tamponade in one patient. Myocardial infarction was suggested by transesophageal echocardiography in 7%, and 14% had significantly reduced left ventricular function. Eight patients underwent operation based on transesophageal echocardiography alone. Intraoperative transesophageal echocardiography, performed in 20 patients, verified retrograde flow in the true lumen after femoral cannulation. Transesophageal echocardiography documented postrepair persistence of the intimal flap in aortic segments that were not operated on in all patients. Secondary tears and flow in the false lumen were detected in 35% of patients. We conclude that transesophageal echocardiography allows expedient and accurate diagnosis and classification of aortic dissection, and we recommend it as the primary bedside diagnostic modality. It can especially identify patients requiring surgical intervention without further delay caused by other diagnostic procedures.

Adult↗
PubMed1992

Improved endothelialization of postfixation treated biological vascular grafts.

Preliminary in vitro and in vivo studies have shown that endothelialization is improved by a detoxifying postfixation treatment of glutaraldehyde (GA) fixed bovine pericardial patches and grafts. To test whether this is also true for GA tanned human vein (HUV) grafts, patches of commercially available HUV grafts (MHUV), postfixation treated HUV grafts (PTHUV) and GA fixed HUV granfts (GAHUV) were endothelialized in vitro. Eight pairs of MHUV and PTHUV grafts were implanted as femoropopliteal grafts in eight sheep. Endothelial cell adherence was significantly better on PTHUV (11910 +/- 4413 cells/cm2) than on MHUV (6545 +/- 2835 cells/mm2; p = 0.0007) and on GAHUV (3563 +/- 1638; p = 0.0001) one day after cell seeding. After eight days of culture significantly more cells spread on PTHUV material than on MHUV (p = 0.0002), but none of the cultures on GAHUV remained viable. Four PTHUV grafts occluded in the femoropopliteal position, mostly because of kinking, so that only in four pairs of grafts could the thrombus-free surface be compared by planimetry. Again PTHUV material was covered more by endothelial cells than was MHUV material. On PTHUV endothelial cells spread directly on the graft material while on MHUV these cells spread on a layer of fibrin and macrophages. Postfixation treatment of GA-fixed biological graft material by amino-acid solutions improves the biocompatibility of the material and enhances in vitro as well as spontaneous in vivo endothelialization.

Animals↗
PubMed1992

New aspects of the degeneration of bioprosthetic heart valves after long-term implantation.

Bioprosthetic heart valves removed 76 to 150 months after implantation were morphologically investigated to correlate structural alterations with clinical failure modes. Traditional morphologic methods of evaluating valvular heterografts, such as microradiography and electron microscopy, were complemented by undecalcified ground sections, a new technique for analyzing the distribution of mineral deposits. Apart from well-investigated mechanisms that accelerate tissue degeneration, our observations point to additional facts: (1) phagocytosis of collagen fibrils and elastic material by macrophages and foreign body giant cells in areas near tears and perforations and (2) initial calcification indicated by delicate crystals in the intercellular space arranged in close relation to the periodicity of the cross-striation pattern of collagen fibrils. The present report not only calls attention to degenerative changes that are enhanced by mechanical stress but also underlines phagocytosis as an important mechanism in the destruction of bioprosthetic heart valves.

Bioprosthesis↗
PubMed1992

Effects of coronary artery bypass grafting on global and regional myocardial function. An intraoperative echocardiographic assessment.

The immediate effect of coronary artery bypass grafting on global and regional myocardial function was studied by means of epicardial two-dimensional echocardiography during operations in 20 patients. Echocardiograms were recorded before cardiopulmonary bypass and 5 and 30 minutes after bypass. Global left ventricular function was expressed as percent short-axis area change and regional function as percent fractional area change. Segments were classified according to their baseline function as normal (percent fractional area change greater than 40%), moderately hypokinetic (percent fractional area change 21% to 40%), or severely dysfunctional (percent fractional area change less than 20%). Percent short-axis area change was significantly reduced immediately after cardiopulmonary bypass (from 42.0% +/- 4.6% to 34.9% +/- 3.0%, p less than 0.05) but had returned to baseline 30 minutes after bypass (42.6% +/- 4.0%). Similarly, function of normal and moderately hypokinetic segments decreased significantly immediately after cardiopulmonary bypass (normal segments: percent fractional area change 56% +/- 0.9% before bypass to 42.3% +/- 1.5% after bypass, p less than 0.0001; moderately hypokinetic segments: 31.0% +/- 0.9% to 25.1% +/- 1.4%, p less than 0.002). Both normal and moderately hypokinetic areas regained baseline function by 30 minutes after bypass (normal segments: 53.4% +/- 1.6%; moderately hypokinetic segments: 35.4% +/- 2.0%). In contrast, severely dysfunctional segments were found to be significantly improved immediately after bypass (14.7% +/- 0.9% before bypass to 27.7% +/- 2.1% after bypass, p less than 0.0001). This improvement was maintained 30 minutes after bypass (22.8% +/- 1.5%, p less than 0.001). We conclude that coronary revascularization exhibits an immediate beneficial effect on chronically underperfused myocardium having severely depressed baseline function. However, in normal and moderately hypokinetic areas, the depressant effects of global ischemia and reperfusion prevail in the immediate postbypass period, leading to a global depression of cardiac function.

Angina Pectoris↗
PubMed1992

Glutaraldehyde affects biocompatibility of bioprosthetic heart valves.

A marked release of glutaraldehyde from commercially available pericardial bioprosthetic heart valve (BHV) material in washing solutions was found by high performance liquid chromatography (up to 1.8 ppm of glutaraldehyde per gram of dry tissue). In vitro endothelial cell proliferation rate was impaired dose-dependently in the presence of increasing glutaraldehyde concentrations of the cultivation medium (r = 0.9; p less than 0.05). Cultivation of endothelial cells was impossible on the surface of commercially available BHV material, but successful and uninhibited when toxic glutaraldehyde ligands of the BHV material were antagonized by treatment with L-glutamic acid.

Animals↗
PubMed1991

[Neurologic and psychiatric complications after heart surgery].

In 63 patients undergoing heart operations with extracorporeal circulation (47 males, 16 females, mean age 54 years; coronary artery bypass in 38 cases, valvular surgery in the rest) postoperative neurological and psychiatric complications were evaluated. 18 patients (29%) had no complications, whereas 35 patients (56%) showed minor or transient neurological symptoms, and 9 patients (14%) exhibited severe symptoms. Nine of the patients had slight psychiatric disturbances (affective disturbances, disorientation). No correlation was found between risk factors (age, nicotine abuse, hypertension, hypercholesteremia, neurologic and cardiac history), intraoperative parameters (duration of extracorporeal bypass, aortic clamp time, deviation of mean arterial pressure), postoperative parameters (internal complications) and the complication rate. Therefore no predisposing factors could be identified.

Adult↗
PubMed1991

Computerized acquisition and evaluation of whole blood aggregometry data.

A special-purpose software package has been developed to acquire and analyze analog signals from a whole blood aggregometer. Up to four independent blood samples can be analyzed simultaneously or with arbitrary delays in time. The user menu ensures proper calibration prior to each measurement and provides a real-time graphic display of the signals. From analog/digital converted data, several "derived diagnostic quantities" are calculated. They are constructed with the aim to mimic the process of visual inspection of aggregometry curves and thus place the intuitive diagnostics of blood platelet function on a quantitative basis.

Computer Graphics↗
PubMed1991

A beat-by-beat analysis of electrocardiograms from cardiac transplant recipients.

A software system is described for producing a beat-by-beat analysis of the electrocardiograms from patients after heart transplantation. Pacemaker spikes are automatically detected and eliminated from the signals. R waves are located by a robust and accurate two-step algorithm. Based on the variable length of single heart beats, the Fourier coefficients of three orthogonal surface leads and of two intracardiac leads are calculated beat-by-beat. Power spectra are then obtained by combining contributions from the variable fundamental frequency and its multiples (harmonics) into fixed frequency classes of 1 Hz width and averaging over 60-120 cardiac cycles. Additionally, averaged beat-by-beat power spectra are calculated for windowed QRS complexes and T waves. As by-products, single beat quantities, such as R-R and R-T intervals, averaged signals for all leads, and the orientational autocorrelation function of the electrical vector of the heart, are obtained. Following beat-by-beat evaluation, mean values and standard deviations are obtained for all quantities.

Algorithms↗
PubMed1991

Transesophageal echocardiographic evaluation in mechanically assisted circulation.

Transesophageal echocardiography (TEE) has assumed an increasing importance in cardiothoracic surgery, but its use in patients with mechanically assisted circulation is unclear. We performed TEE in 11 patients: total artificial heart (TAH) 2, right ventricular assist device (RVAD) 2, left ventricular assist device (LVAD) 6, biventricular assist device (BVAD) 1. TEE was helpful in three areas. (1) selection of the assist device (AD): evaluation of left and right ventricular function allows differentiation of left, right or biventricular failure. (2) management of patient and optimization of pump performance: in all patients, correct cannula position and pump flow could be identified. Right ventricular failure in the presence of LVAD was found to cause hemodynamic instability in 4 patients. In 1 patient with repeated RV dilation and hypotension despite RVAD, TEE allowed optimal pump settings to be determined. (3) weaning from AD: Recovery of ventricular function can be assessed prior to weaning and repeatedly monitored during weaning. TEE in TAH is limited to problems such as identification of atrial thrombus or inflow valve dysfunction. We conclude that TEE is useful in the setting of mechanically assisted circulation for AD selection, improvement of patient management, optimization of pump performance and during weaning from AD.

Assisted Circulation↗