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M Dahm

Publications and source records attributed to M Dahm.

71 records · Page 4Linked to original sources
PubMed1990

Immunogenicity of glutaraldehyde-tanned bovine pericardium.

Glutaraldehyde-tanned bovine pericardium was tested for its ability to induce immunologic responses in vivo. Sections of glutaraldehyde-tanned bovine pericardium were implanted between the abdominal muscles of rats and guinea pigs. Control animals received Dacron implants. Lymphocytes and sera from animals were isolated at 2 and 4 weeks after implantation (four animals per group per time). Tritiated thymidine incorporation and an enzyme-linked immunosorbent assay were used to measure T- and B-lymphocyte responses to glutaraldehyde-tanned bovine pericardium antigens. At the same time points, implants and surrounding tissue from all animals were processed for histologic data. Results show that T-lymphocytes from animals with glutaraldehyde-tanned bovine pericardium implants responded significantly (p less than 0.001) to glutaraldehyde-tanned bovine pericardium antigens in vitro but not to Dacron. In contrast, lymphocytes from animals with Dacron implants failed to respond to glutaraldehyde-tanned bovine pericardium or Dacron preparations. Results of enzyme-linked immunosorbent assay show that animals with glutaraldehyde-tanned bovine pericardium implants produced antibody directed against glutaraldehyde-tanned bovine pericardium antigens. Histologic study revealed a dense mononuclear and multinuclear giant cell infiltrate at the interface between glutaraldehyde-tanned bovine pericardium and surrounding host tissues, with focal degradation of implant collagen. Dacron elicited a nonspecific lymphocytic and foreign body-type reaction. These results indicate that glutaraldehyde-tanned bovine pericardium can induce immunologic responses in vivo consistent with a host-versus-graft reaction.

Abdominal Muscles↗
PubMed1990

Chordal replacement in mitral valve repair.

Chordal replacement greatly extends the possibility of repair of atrioventricular valves. Both glutaraldehyde-tanned xenograft pericardial chordae (GTXP) and extruded polytetrafluorethylene chordae (ePTFE) heal to papillary muscles and cusps. Neither type elongates or shrinks. GTXP may thicken and stiffen with time. ePTFE is covered by a normal fibrosa and intima (a new chorda is grown around the ePTFE suture) experimentally and in small sizes (e.g., CV 5), retains flexibility. The results of late follow-up (5-10 years) with GTXP chordae and early follow-up (6-58 months) with ePTFE chordae are encouraging.

Adult↗
PubMed1989

[Pseudarthrosis of the scaphoid: frequency, pathogenesis and course].

Eight-three scaphoid pseudo-arthroses were found amongst 1.104 scaphoid examinations. Sixty-seven were present at the first examination and 16 pseudoarthroses developed amongst 252 scaphoid fractures. Men were affected predominantly, particularly in the 20 to 40-year old group. Fractures in the proximal third of the scaphoid and vertical oblique fractures had a particular tendency to pseudo-arthrosis formation. The operative treatment of choice is a Matti-Russe bone graft. Only one patient in seven with definite scaphoid pseudo-arthrosis showed firm fusion.

Adult↗
PubMed1989

Hemodynamic effects of high-frequency jet ventilation in dogs with a chronically banded pulmonary artery.

Two to seven weeks after banding the main pulmonary artery, the hemodynamic effects of high-frequency jet ventilation (HFJV) and conventional mechanical ventilation (CMV) were studied in dogs with and without PEEP. In comparison with CMV, HFJV significantly increased cardiac index, stroke index (SI), left ventricular stroke work index, and oxygen delivery index, and decreased pulmonary vascular resistance index both with and without PEEP; however, there were significant decreases in PaO2 and increases in intrapulmonary physiologic shunt ratio in HFJV without PEEP. SI without PEEP was significantly greater with HFJV when the peak airway pressure was synchronized with the diastole in pulmonary arterial pressure (PAP) than with CMV and with HFJV synchronized with the systole in PAP. These findings suggest that HFJV has hemodynamic advantages over CMV in dogs with chronically banded pulmonary artery and dilated right ventricle.

Airway Resistance↗
PubMed1989

Acute hemodynamic response to intravenous enoximone: an animal study and preliminary report in infants after cardiac surgery.

In light of previous studies in adults, we considered that enoximone could be useful in treating children with therapy-resistant cardiovascular insufficiency. Prior to clinical administration, we investigated the cardiovascular properties of enoximone in anesthetized and ventilated piglets characterized by small stroke volume and high heart rate. Enoximone was administered intravenously in increasing doses (0.25, 0.5, and 1 mg/kg). The animals were monitored with heart rate, systemic and pulmonary arterial pressures, and continuous electromagnetic flow. Enoximone induced a dose-dependent flow increase, whereby heart rate and systemic arterial pressure changed only slightly. With regard to persistent pulmonary hypertension in newborns, enoximone was also used in piglets to investigate the effects on endotoxin-induced, dopamine-resistant pulmonary hypertension. Enoximone (1 mg/kg i.v.) was given immediately after E. coli endotoxin (1.5 micrograms/kg i.v.) and inhibited the endotoxin-induced, eicosanoid-mediated pulmonary hypertension, whereas during infusion of dopamine (2 mg/kg/h), no drop in systemic blood pressure could be observed. In the clinical study, six infants with post-cardiac surgery low output syndrome despite maximal catecholamine inotropic support were given enoximone (i.v. bolus of 0.2, 0.5, or 1 mg/kg followed by continuous infusion of 7.5-10 micrograms/kg/min). Continuously measured mixed-venous oxygen saturation increased in a dose-related manner. Cardiac output increased significantly by 28%, accompanied by a decrease of arteriovenous oxygen content difference and O2 utilization ratio. The preliminary results show that intravenous enoximone produces acute useful hemodynamic effects in infants, in particular allowing a weaning of vasoactive amines.

Animals↗
PubMed1989

Concentrations of some trace elements (Se, Zn, Cu, Fe, Mg, K) in blood and heart tissue of patients with coronary heart disease.

We measured Se, Zn, Fe, Cu, Mg, and K in blood and heart tissue of patients with coronary heart disease. Such patients have subnormal selenium concentrations in serum, whole blood, and (calculated per gram of hemoglobin) erythrocytes. Concentrations of zinc and copper in serum were also subnormal in these patients. Heart tissue collected from these patients during bypass surgery was analyzed for Se, Zn, Fe, Cu, Mg, and K; results are expressed in terms of wet weight and in relation to nitrogen and phosphorus content. Concentrations of these elements in blood are correlated with those in heart tissue. Selenium concentrations in serum correlated positively with those in tissue but not with those in erythrocytes. We found no association between concentrations of zinc, iron, copper, magnesium, and potassium in serum and the corresponding concentrations in heart tissue. There was a moderately positive correlation between the concentration of ferritin in serum and that of iron in tissue. We conclude that the turnover rate for selenium in tissue is similar to that in serum but greater than that for erythrocyte selenium. The concentrations of these six elements in heart tissue are partly correlated with the ejection fraction of the left ventricle.

Copper↗
PubMed1987

The effect of isometric short-term electrical stimulation on denervated muscle.

Electrical stimulation was applied daily for 20 minutes to denervated rabbit extensor digitorum longus muscle. One group was stimulated with short tetani, another with 1-Hz frequency, using isometric contractions for both. Tetanic stimulation induced severe fibrosis and is harmful to denervated muscle. One Hertz stimulation retarded denervation-induced fatigue and atrophy, as well as slowing of contraction time.

Animals↗
PubMed1987

[Assessment of heart valve reconstructive measures using intraoperative transesophageal contrast echocardiography].

In 30 patients (6 mitral stenoses, 13 mitral insufficiencies, 12 tricuspid insufficiencies) intraoperative transoesophageal contrast echocardiography (TEE) was performed to examine the valve function after AV valve reconstruction. In the beating heart 1 ml of contrast medium was injected into the ventricle to assess the success of valve reconstruction by the extent of regurgitation into the left or right atrium respectively. In all 12 patients successful tricuspid valve reconstruction was detected. In 16/19 cases with mitral valve repair successful reconstruction has been demonstrated. In another 3 patients severe mitral insufficiency after valve repair was detected by TEE, finally intraoperative decision for valve replacement was made.

Echocardiography↗
PubMed1987

Intraoperative evaluation of reconstruction of the atrioventricular valves by transesophageal echocardiography.

In a total of 30 operations the mitral valve was reconstructed in 18, the tricuspid valve in 11, and both AV-valves in one patient. The result of reconstruction was tested first in the open arrested heart by injection of crystalloid solution into the appropriate ventricle either through the reconstructed valve or one of the great arteries. Upon termination of cardiopulmonary bypass the valve function was examined in the beating heart by means of transesophageal contrast echocardiography (TEE). For visualization 0.5-1.0 cc of agitated Gelifundol was injected into the ventricle. In 22 patients open testing as well as echocardiographic visualization showed identical and good operative results. In 6 patients TEE revealed mild insufficiency, but no further surgery was done. In three patients with mitral valve repair, contrast-echocardiography showed severe insufficiency, which had not been detected during cardiac arrest. In these patients changes in the level of the subvalvular apparatus caused systolic dislocation of the leaflets and massive reflux. Because of these findings definive valve replacement was performed in the same operation. Intraoperative TEE is a simple, safe and reliable method für assessment of AV-valve repair, thereby motivating the surgeon towards valve preservation and improving the outcome of valve surgery.

Adult↗
PubMed1987

Double inlet left ventricular main chamber, subaortic small left sided right ventricle and interrupted aortic arch type A. What operation is indicated when?

A case of a 23 year old female patient who suffered from the complex congenital heart lesion of a double inlet left ventricular main chamber, subaortic small left sided right ventricle and interrupted aortic arch type A is reported. With equally high blood pressures, the perfusion in the upper half of the body was maintained through the ascending aorta while the lower half and the lungs were supplied through the pulmonary artery and a patent ductus arteriosus (PDA). Angiographically, the bulbo-ventricular foramen appeared to be nonrestrictive. However, distinct signs of muscular subaortic stenosis were detected. The hemodynamic status principally allowed surgical correction when this became necessary because of increasing left heart failure. Treatment for this complex lesion undoubtedly required reduction of pulmonary perfusion, even when associated with the danger of increasing cyanosis. Various forms of surgical treatment (functional correction, palliative procedures) were discussed. The most elegant was performed without cardiopulmonary bypass: this consisted in connection of the pulmonary artery with the descending aorta using a 16 mm Dacron tube, reconstruction of the aortic arch by a prostheso-subclavian synthetic graft, suture ligation of the PDA, and banding of the pulmonary artery trunk distal to the origin of the prosthesis. One year after the operation, the patient's physical performance has improved. Moreover, despite the disappearance of cardiac failure she has not become more cyanotic during exertion.

Adult↗
PubMed1987

[Intraoperative assessment of the reconstruction of atrioventricular valves using transesophageal echocardiography].

To obtain good results in cardiac valve reconstruction surgery it is necessary to assess intraoperatively the efficiency of mitral or tricuspid valve repair. In 15 patients (three with mitral stenosis, 12 with mitral insufficiency) the mitral valve, in eight patients the tricuspid valve and in two patients both av-valves were reconstructed individually by commissurotomy and/or annulorrhaphy. During cardiac arrest, the valves were tested by filling the left or right ventricle with saline solution. After weaning from the extra-corporeal-circulation (ECC) I-2 cm3 of agitated Gelifundol were injected into the ventricle and the amount of regurgitation of micro-bubbles into the atrium was assessed by intraoperative two-dimensional transesophageal echocardiography. In 20 patients, testing during cardiac arrest and contrast echocardiography showed identical and good results. In two patients, the efficiency of mitral or tricuspid reconstruction could be finally verified by transoesophageal echocardiography. In another patient who was operated because of HOCM and a severe mitral insufficiency, the Bigelow procedure was combined with mitral valve reconstruction. Intraoperative open testing showed a good functional result, but a remaining severe mitral insufficiency was detected by transesophageal contrast echocardiography. An intraoperative decision for valve replacement was made. Our results show that transesophageal contrast echocardiography is a simple and accurate method of assessing the efficiency of valve reconstruction procedures. In some cases it gives more information than testing during cardiac arrest.

Adult↗
PubMedDate not supplied

Assessment of successful valve reconstruction by intraoperative transesophageal echocardiography (TEE).

In 17 patients (10 patients with mitral insufficiency, 5 patients with tricuspid regurgitation, 2 patients with mitral stenosis) the result of valve reconstruction was evaluated by intraoperative two-dimensional transesophageal contrast-echocardiography (TEE). Therefore, 1-2cc of an agitated contrast-medium (Gelifundol) were injected into the left or right ventricle. The result of reconstruction was assessed by the extent of regurgitant microbubbles into the left or right atrium. A successful valve repair could be demonstrated in 15 patients without or with only minimal regurgitation of contrast-fluid. In one patient residual severe mitral insufficiency after valve reconstruction could only be detected when valve function was examined by contrast-TEE in the beating heart. An intraoperative decision for valve replacement was made. In another patient, mild to moderate residual mitral incompetence was shown; no further surgical intervention was done. By TEE the function of reconstructed valves can be examined under physiological conditions in the beating heart. Surgeons can obtain additional intra-operatively information and certainty about the result of reconstruction and an early decision for valve replacement can be made if necessary.

Adult↗
PubMedDate not supplied

Diagnostic image workstations for PACS.

Image workstations will be the 'window' to the complex infrastructure of a PACS with its intertwined image modalities (image sources, image data bases and image processing devices) and data processing modalities (patient data bases, departmental and hospital information systems). They will serve for user-to-system dialogues, image display and local processing of data as well as images. Their hardware and software structures have to be optimized towards an efficient throughput and processing of image data.

Hospital Information Systems↗
PubMedDate not supplied

Evaluation of a stented polyurethane mitral valve prosthesis.

In the search for the perfect valve prosthesis, polyurethane has been used for its excellent physical properties, but thrombosis and embolism have been real problems. The authors investigated the performance and durability of a 23 mm vacuum formed polyurethane Tricuspid Semilunar Valve, in the mitral position. The valve was implanted in eight sheep using standard cardiopulmonary bypass and intermittent aortic cross clamping. Two early failures were due to valve tears. After modification of the manufacturing process, six further valves were implanted in six sheep. All were anticoagulated with warfarin. The valves were calcified on echocardiography and had increasing transvalvular gradients beginning 3 months postoperatively. All six survived and were killed 1-2.5 years after implantation. Despite gross calcification of the leaflets, medium-term function was good. Careful serial sections of brain showed no evidence of thromboembolism. Both kidneys contained small calcium emboli, but no evidence of infarction. Despite calcification, with good medium-term function and no cerebral emboli, this valve may find application in temporary cardiac assist devices.

Animals↗