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Biomedical subjects

H Oster

Publications and source records attributed to H Oster.

At least 55 records · Page 3Linked to original sources
PubMed1979

Surgical treatment of double-outlet left ventricle in 2 patients with D-position and L-position of the aorta.

Two cases of double-outlet left ventricle (DOLV) are described, 1 with D-position and 1 with L-position of the aorta. Both patients had situs solitus, atrioventricular concordance with D-relationship of the two ventricles, a ventricular septal defect, and subpulmonary stenosis. The patient with D-position of the aorta was operated on using a technique similar to that for repair of Fallot's tetralogy but including emergency implantation of a bioprosthesis into the pulmonary artery position on the eighth postoperative day. Surgical correction in the patient with L-position of the aorta required the implantation of a composite valved conduit between the right ventricle and the pulmonary artery. The various surgical techniques for correction of DOLV are described, and the literature is reviewed. Postoperative right heart failure in both patients is explained by the impaired function of the right ventricle being exposed to gross pulmonary incompetence or by the persistence of elevated right ventricular pressure.

Adult↗
PubMed1979

Reconstruction of the right ventricular outflow tract including pulmonary valve replacement in 6 children under two years of age.

In 6 children under 2 years of age correction of congenital heart defects required reconstruction of the right ventricular outflow tract including replacement of the pulmonary valve. Outflow tract reconstruction consisted in implantation of a size 14 valved conduit in 2 patients with d-TGA and subpulmonary stenosis and 1-TGA and subpulmonary stenosis, and a size 16 valved conduit in 2 other patients with truncus arteriosus. In 2 children with DOLV, VSD and aneurysm of the pulmonary artery trunk, the pulmonary valve was replaced by porcine heterografts, sizes 19 and 21 respectively, after primary patch reconstruction of the right ventricular outflow tract. There was one operative death in a child with d-TGA, intact ventricular septum and severe subpulmonary stenosis. This child died in low cardiac output, probably because too much contractile muscle was lost at the site of anastomosis with the conduit. For reconstruction of the right ventricular outflow tract, pulmonary valve replacement has proven mandatory in cases with pulmonary hypertension in order to prevent postoperative right heart failure. Similarly, in cases with pulmonary stenosis and hypoplastic pulmonary arteries, postoperative pulmonary insufficiency can be deleterious to the right ventricle.

Aneurysm↗
PubMed1979

[Aortopulmonary window: external occlusion in the newborn (author's transl)].

Correction of aortopulmonary window in the newborn infant carries a high operative risk. Even later in life operative mortality with or without cardiopulmonary bypass may amount to 30% and more. To reduce the operative risk a new technique for closure of the aortopulmonary window was employed in 2 infants aged 3 and 4 weeks, respectively. With this method the communication is externally occluded by 4 or 5 mattress-sutures, buttressed with Dacron strips on each side. Both infants underwent emergency operation because of intractable heart failure. The postoperative course was uneventful and both were discharged from the hospital in good condition.

Aorta↗
PubMed1978

[Injuries of the oesophagus (author's transl)].

34 cases of perforation of the oesophagus are reported, partly treated at the surgical and partly at the E.N.T. department. Air emphysema of the throat or of the mediastinum and/or escape of the contrast medium was observed in all patients. The main cause of perforation was endoscopic examination. The patients partly underwent conservative and partly surgical therapy, both groups showing similar mortality rates. Small perforations in the upper third of the oesophagus can be treated conservatively, whereas perforations in the lower two thirds, especially with involvement of the pleura, pericardium or peritoneum, need rapid surgical intervention, as the prognosis improves in relationship to the rapidity with which treatment is instituted following perforation.

Adult↗
PubMed1976

[A new design for a totally artificial heart: the ellipsoid heart (author's transl)].

Thromboembolic complications represent the main limiting factor in cardiac replacement by totally artificial hearts in calves at present. Thrombus formation within artificial hearts is caused by the appearance of stagnation areas. The ellipsoid heart eliminates stagnation areas by virtue of its production as a one-piece membrane. The heart is driven pneumatically and functions as a diaphragmatic blood pump. The stroke volume is 178 cm3 and the maximal cardiac output 15.8l/Min. Three acute experiments demonstrated a high degree of haemodynamic efficiency without compression of, or interference with surrounding structures, especially the inferior vena cava or the right atrium.

Animals↗
PubMed1976

Material and design factors in thromboembolization in total artificial heart recipients living 100-2,000 hours.

When total artificial heart (TAH) recipients live over 100 h it is possible to evaluate the thrombogenicity of design and biomaterials. In 20 consecutive TAH recipients of the Jarvik heart with Björk-Shiley valves we compared rough (Dacron fibril-coated Silastic) and smooth (Biomer and Avcothane) blood surfaces. The mean survival times with rough surfaces was 296 h, with smooth surfaces 545 h. The present designs necessitate a sharp angle junction between the diaphragm and housing, creating stagnation areas and turbulences which induce thromboembolization. The valve rings and struts are another constant source of thromboembolism. Of the 80 valves, 41% showed thrombus deposition independent of anticoagulation. The polyurethane surfaces, in contrast to the fibrilized surfaces, were very clean and free of thrombi at autopsy. The thromboembolization was not dependent on anticoagulation and platelet adhesiveness inhibitor in hearts with rough surfaces. Based on 20 experiments including 78- and 94-day TAH survivors (Avcothane and Biomer hearts), there is an indication of the need of a new ventricular design. The ultimate design should generate physiological pulse waves without turbulences or stagnation areas within the device.

Animals↗
PubMed1975

Survival for 18 days with a Jarvik-type artificial heart.

This is a report of an experiment wherein a calf had its natural heart replaced with an artificial heart and survived for 18 days and 20 hours. All measured physiologic parameters remained normal until the fourteenth day. Thereafter a gradual persistent rise in venous pressure and signs of a decreased cardiac output occurred. However, the animal outwardly appeared normal until the eighteenth day. During the nineteenth day it became comatose and was killed. At autopsy large thrombi were found in both atria, impairing ventricular filling, resulting in venous congestion and diminished cardiac output. This extended survival time and our ability to understand and eliminate the problems associated with artificial heart implantation give support to our hope that artificial hearts for man will be possible in the not too distant future.

Acute Kidney Injury↗
PubMed1975

Thrombus generation within the artificial heart.

The sites of thrombus formation in the Jarvik III artificial heart were studied in 20 consecutive calf experiments. Identical design and implantation procedures were used with two different surfaces. The 10 anticoagulated calves receiving Dacron-fibrilized silicone rubber surfaces survived an average of 296 hours. In contrast, the 10 nonanticoagulated calves with smooth poyurethane hearts survived 545 hours. The polyurethane surfaces were constantly clean. However, the rough surfaces were coated with variable amounts of thrombi. The sharp angle between the diaphragm and housing contained varying amounts of thrombi deposits in 75 per cent of the cases. Thrombe deposition occurred on 41 per cent of the valves. These thrombe were the source of emboli into the kidney, brain, and lungs. Turbulences and stagnation areas generated thrombus formation. Anticoagulation did not prevent thrombus formation. It would appear that heart free of turbulence and stagnation areas must be designed to eliminate thromboembolism.

Animals↗
PubMed1971

[Prenatal disorders].

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Abnormalities, Drug-Induced↗