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Biomedical subjects

J G Losman

Publications and source records attributed to J G Losman.

16 recordsLinked to original sources
PubMed1979

Morphological changes in 49 chacma baboons after cardiac allografts.

The morhpological changes in 49 chacma baboons after cardiac transplantation were studied by light and electron microscopy. Non-immunosuppressed grafts were tolerated for an average of 10 days and immunosuppressed grafts for 18 days. Serial biopsy specimens of non-immunosuppressed grafts showed a progression in severity of rejection changes. Electron microscopy mirrored the light microscopic changes. Rejection changes in the baboon appear similar to those encountered in human and canine allografts. Heterotopic transplants showed more severe grades of rejection than would be compatible with life in orthotopic transplants.

Animals↗
PubMed1978

Risk factors in surgical correction of congenital heart defects in early childhood.

The technique of surface-induced hypothermia, circulatory arrest and limited extracorporeal circulation was used in the surgical correction of congenital heart defects in 125 young children. Hospital mortality was 18% and no death could be attributed to the surgical technique. An analysis of risk factors demonstrated that successful corrective surgery was not significantly related to age, body weight or pulmonary vascular obstructive disease. In transposition of the great arteries, the presence of a ventricular septal defect was associated with an increased mortality. Emergency operations performed because of severe hypoxaemia carried a high mortality, especially in patients with tetralogy of Fallot.

Child↗
PubMed1978

Use of a double atrial-triggered standby pacemaker system for a patient with a biventricular bypass heterotopic cardiac homograft.

In a patient who had a biventricular bypass heterotopic cardiac homograft a double atrial-triggered standby pacemaker system was implanted to allow sequential atrial pacing of both hearts. The system design permitted either the recipient or the donor heart to dictate the rate of its fellow, depending on which heart had the faster spontaneous sinus rate at any time. Alternative methods for achieving sequential pacing are discussed.

Adult↗
PubMed1978

Normal cardiac function with a hybrid heart.

A left ventricular bypass procedure using a cardiac allograft was performed in a patient with a long history of rheumatic heart disease and two aortic valve replacements. Normal cardiac function was reestablished, and the only problem following transplantation was that of serious arrhythmias involving the recipient heart. Eighteen months after left ventricular bypass bacterial endocarditis which was resistant to medical treatment developed on the aortic prosthesis. The patient underwent operation, the prosthesis was removed, and the recipient left ventricle was partially resected and excluded from the circulation. Since then the patient has been asymptomatic and, at the time of writing three years after cardiac allograft, he is our longest survivor.

Arrhythmias, Cardiac↗
PubMed1978

Evaluation of endomyocardial biopsy in the diagnosis of cardiac rejection. A study using bioptome samples of formalin-fixed tissue.

The reliability of endomyocardial bioptome samples in detecting cardiac rejection was assessed in 26 formalin-fixed previously transplanted hearts. Thirteen human donor hearts (mean postoperative survival 128 days) and 13 baboon donor hearts (mean survival 16.5 days) were studied. Twenty samples were taken under direct vision from the endomyocardium of each heart with an Olympus bioptome catheter. A total of 397 tissue samples was examined "blindly" histologically (177 human and 220 baboon). The bioptome samples were assigned a histological rejection score and then compared with the score accorded multiple tissue sections from the same heart. Sample scores agreed with tissue section scores as follows: humans 86% (samples showed more severe alterations in 5% and less severe in 9%) and baboons 57% (samples more severe in 40% and less severe in 3%). Only 2 false-negative samples were encountered among 285 tissue samples from hearts showing rejection. Changes of rejection were equally distributed between the left and right ventricles. Endomyocardial sampling proved an accurate means of detecting the presence of rejection. In the baboon hearts the endomyocardium tended to show more severe changes than the rest of the myocardium.

Animals↗
PubMed1978

Cardiac surgical research and heart transplantation in Papio ursinus.

The use of non-human primates stems from the concern for employing an animal genetically closely related to man. During a 3 year period over 300 baboons were handled in the Cardiac Research Unit and more than 60 heterotopic cardiac transplantations were performed. The baboon presents multiple advantages if compared with the problems arising from the use of the dog or the pig in cardiac surgical experimentation. This experimental work illustrated these advantages and demonstrated that heterotopic cardiac transplantation is a valuable model for treatment of patients in end stage cardiac failure. The procedure has been performed successfully in 16 patients, 12 being presently alive, 1-36 months following transplant.

Animals↗
PubMed1978

Subvalvular left ventricular false aneurysm complicating mitral valve replacement.

Surgical replacement of the mitral valve by a prosthetic valve may lead to localized disruption of atrioventricular continuity resulting from direct surgical trauma or from delayed rupture of the weakened annulus. Such disruption leads to subepicardial hematoma formation that may remain localized if pericardial adhesions are present. Of two patients who suffered this complication, the first died of rupture of the epicardial hematoma. The hemorrhage in the second patient was contained by pericardial adhesions and had organized, thus resulting in a subannular left ventricular false aneurysm. The aneurysm was found incidentally at autopsy after the patient died of cerebral embolism from prosthetic valve thrombi.

Female↗
PubMed1977

Heterotopic cardiac transplantation with a xenograft for assistance of the left heart in cardiogenic shock after cardiopulmonary bypass.

One of the indications for the use of the heterotopic cardiac transplant is temporarily to support a failing heart in the anticipation of its recovery when all other measures of support have been unsuccessful. Human donors are not always available when required and we decided to use a xenograft for this purpose when the need arose. This report details our experience with a baboon and a chimpanzee cardiac xenograft transplant in the heterotopic position. We have found (a) that the operation is technically feasible; (b) that the xenograft will support the failing circulation, but that the more support required, the bigger the xenograft should be and the species chosen accordingly; (c) that severe acute rejection will occur within 4 days and the procedure should therefore only be employed where there is evidence that the patient's own heart function will recover rapidly.

Adult↗
PubMed1977

Human technology after cardiac epigenesis. Artificial heart versus cardiac transplantation.

Cardiovascular disease is the chief cause of death in technologically advanced countries and accounts for more than 50% of all deaths in the USA. For a patient with end-stage cardiac failure the only treatment presently available is organ replacement, either by transplantation or by the use of a mechanical heart. Transplantation has demonstrated its value: survival of more than 8 years and restoration of a normal quality of life to patients who were in end-stage cardiac decompensation. However, the prospect of routine clinical application of an artificial heart remains distant. The development of a totally implantable artificial heart still presents a series of challenging engineering problems with regard to strict constraints of size, weight, blood-material compatibility, adaptability of output to demand, efficiency and reliability of the power supply, and safety if nuclear fuel is used. The totally artificial heart is presently not an alternative to the cardiac allograft, but could provide short-term support for patients awaiting cardiac transplantation.

Anemia, Hemolytic↗
PubMed1977

Treatment of paraquat poisoning with the membrane oxygenator: a case report.

A fatal case of progressive pulmonary fibrosis in a 13-year-old boy, due to poisoning by the weed-killer paraquat, is described. Attempted treatments included extracorporeal circulation. The management is discussed in the light of the histological observations, and the pathophysiology of the condition.

Adolescent↗
PubMed1977

Myocardial fibrinolytic activity in allogenic cardiac rejection.

The relationship between alterations in myocardial fibrinolytic activity and the degree of graft tolerance or rejection was studied in 22 nonimmunosuppressed heterotopic cardiac transplants in chacma baboons. Fibrinolysis was evaluated on tissue sections and tissue extracts. Fibrinolytic activity was compared with electrocardiographic voltage alterations and multiple myocardial biopsies and terminal heart specimens were examined by light and electron microscopy. Histopathology and reduction in fibrinolytic activity proved superior to electrocardiographic voltage reductions in assessing early cardiac rejection. The two former modalities correlated well with one another. Myocardial histology showed rejection change earlier than fibrinolytic activity reduction.

Animals↗
PubMed1977

The advantage of heterotopic cardiac transplantation over orthotopic cardiac transplantation in the management of severe acute rejection.

The major problems with organ transplantation are rejection of the allograft and the side effects of antirejection therapy. This report describes the successful treatment of a patient in whom rejection of the donor heart developed 10 months after implantation. The recipient's own heart had been left intact and was able to support the circulation during the period of rejection. Indications are that the "rest" period of 10 months was beneficial to the myopathic left ventricle of the recipient's heart.

Adult↗
PubMed1975

Left ventricular bypass.

The removal of the patient's own diseased heart in order to perform a total cardiac transplantation has several disadvantages. A new technique for bypassing the patient's diseased left ventricle by using a cardiac allograft has been developed in our laboratory and applied clinically in 2 patients. This technique carried no direct surgical mortality, and no complications resulting from the patient's own heart being left in situ have been observed thus far. The presence of a second heart lying partly in the anterior mediastinum and partly in the right pleural space appeared to have no deleterious effects. Several advantages over the conventional transplant have been noted and are discussed.

Aorta↗