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Biomedical subjects

M Yacoub

Publications and source records attributed to M Yacoub.

At least 253 records · Page 14Linked to original sources
PubMed1988

Cardiac transplantation in severely ill patients requiring intensive support in hospital.

Sixty four patients were referred for cardiac transplantation from a single cardiac team at this hospital between October 1984 and December 1986. Of these patients, 33 were referred for urgent transplantation, all of whom required intensive treatment in hospital with intravenous infusions of cardiac drugs, intra-aortic balloon counterpulsation, peritoneal dialysis, ventilation, or any combination of these to sustain life. Of these 33 patients, six died while awaiting transplantation, one was removed from the waiting list for a transplant, and 26 received cardiac transplants. There were five deaths within 24 hours of operation and one death 10 days after the operation. Twenty of those who had surgery had a successful outcome of transplantation, but there was one late death 10 weeks postoperatively and a further death 31 months after surgery. Eighteen patients were alive and well 10 to 33 months (mean 19.4 months) after transplantation, with an overall survival rate after surgery of 69%. Provided that surgery can be performed before renal failure has progressed such that renal dialysis [corrected] is necessary, the results are excellent (surgical survival 85.5%) and, we believe, justify the expenditure and staffing requirements necessary to treat these terminally ill patients.

Adolescent↗
PubMed1988

Plexiform lesion in bronchopulmonary anastomosis.

A cellular lesion developed in the bronchial component of a bronchopulmonary anastomosis in a girl of 6 years with primary pulmonary hypertension. Its histological features were consistent with those of a plexiform lesion.

Arterio-Arterial Fistula↗
PubMed1988

Persistence of donor-specific class II antigens in allografted human heart two years after transplantation.

It has been suggested that one of the mechanisms of action of cyclosporin is by abrogation of major histocompatibility complex class II expression. We have tested this hypothesis by following the expression of DR7, a polymorphic determinant of the class II DR locus in cardiac biopsies from 12 heart or heart-lung recipients who were themselves DR7 negative but whose donors were DR7 positive. All patients received cyclosporine and azathioprine immunosuppression. Immunoperoxidase and immunofluorescent techniques were used. The DR7 determinant was found on interstitial structures on donor heart at all times studied, including at 2 years after transplantation. Double immunofluorescent labeling of donor heart before transplantation revealed that more than 60% of the DR7 was on endothelial cells. At later times the proportion of DR7 on endothelial cells increased, but even at 1 year some DR7 was found on interstitial structures not of endothelial origin. The significance of these findings to mechanisms of long-term immunosuppression is discussed.

Azathioprine↗
PubMed1988

Induction of red blood cell destruction by graft-derived antibodies after minor ABO-mismatched heart and lung transplantation.

Heart-lung transplantation (HLT) unlike other solid-organ transplants involves transplantation of a large amount of lymphoid tissue; hence there is considerable potential for graft-versus-host reaction if there is an antigen mismatch between donor and recipient. Due to the shortage of suitable donors, minor ABO-mismatched HLT (group O organs given to A, B, or AB recipients) are performed. Of 84 consecutive HLT at Harefield Hospital, nine fully ABO-matched and nine ABO-mismatched HLT were studied. Six minor ABO-mismatched HLT patients had evidence of immune destruction of recipient's red cells. Haemolysis started from days 4-12 and lasted for a mean of 13 days; in four cases transfusion support was necessary. ABO antibodies incompatible with the recipient ABO antigens, but compatible with the donor, were found in the serum and red cell eluates of these patients. In two cases, these antibodies were detected for over one year after transplantation. These changes were not seen in the fully ABO-matched controls. Our findings suggest that donor-derived lymphocytes from group O organs continue to produce anti-A and/or anti-B after transplantation, and if the recipient is group A, B, or AB, mount a secondary immune response following antigenic stimulation by the recipient's differing ABO antigens. The specific transfusion management of these patients is discussed.

ABO Blood-Group System↗
PubMed1988

Ventilatory and circulatory responses at the onset of exercise in man following heart or heart-lung transplantation.

1. Ventilatory and cardiovascular responses to the onset of voluntary and electrically induced leg exercise were studied in six patients following heart transplantation and five following heart-lung transplantation; the results were compared between the patient groups and also with responses from a group of normal subjects. 2. Oxygen consumption, carbon dioxide production and ventilation and its components were measured over two 30 s periods prior to, and two 30 s periods following, the onset of exercise. Relative changes in stroke volume and cardiac output were derived from ensemble-averaged Doppler measurements of ascending aortic blood velocity over the same 30 s periods. 3. None of the groups of subjects showed any significant differences in responses to voluntary exercise compared to electrically induced exercise of similar work pattern and intensity. 4. Compared to normal controls, the transplanted subjects showed higher resting heart rates which did not increase at the onset of exercise; stroke volume increased, but less than in the normal subjects. The resulting cardiac output increases in the transplanted subjects were minimal compared to the normal subjects. 5. Ventilation and oxygen uptake increased immediately and with similar magnitude in all three groups. 6. These results show that in the same individual it is possible to have an appropriate ventilatory response to the onset of exercise in the presumed absence of a normal corticospinal input to the exercising muscles (electrically induced exercise) and afferent neural information from the lungs and heart, and in the absence of a normal circulatory response to exercise. The mechanisms underlying this ventilatory response remain undetermined.

Adult↗
PubMed1987

Coronary artery infusion of neuropeptide Y in patients with angina pectoris.

Neuropeptide Y was infused into a coronary artery of 6 patients with typical angina but no significant coronary stenosis. 3 patients had transient myocardial ischaemia, shown by typical pain and electrocardiographic change, at doses of 0.2 pmol/kg per min in 2 patients and 1.0 pmol/kg per min in 1 patient. The arteriographic appearances suggested constriction of small vessels rather than constriction of epicardial coronary arteries. The ischaemia was completely reversed by intracoronary administration of isosorbide dinitrate with no adverse sequelae. This is the first demonstration of myocardial ischaemia in man induced by a peptide neurotransmitter.

Adult↗
PubMed1987

Lung biopsy findings in transposition of the great arteries with ventricular septal defect: potentially reversible pulmonary vascular disease is not always synonymous with operability.

Pulmonary vascular structure was analyzed in lung biopsy specimens taken from 28 children, aged 2 months to 15 years, with transposition of the great arteries and ventricular septal defect. Cellular intimal proliferation occurred in infants as young as 2 months, but it increased markedly between ages 7 to 9 and 10 to 12 months, and the increased obstruction was associated with a lower mean percent arterial medial thickness in patients older than 10 months than was found in younger patients. Early generalized arterial dilation appeared without the intimal fibrosis and dilation lesions characteristic of classical grade III and IV pulmonary vascular disease. Intimal abnormalities increased with age and pulmonary artery pressure, but mean percent arterial medial thickness was inversely related to mean pulmonary artery pressure (r = -0.5; p less than 0.0001). Nine patients survived intracardiac repair and six did not. Five of the patients who died were of similar age (12 months or less), had similar preoperative hemodynamic and pulmonary vascular abnormalities compared with the survivors and died after a clinical course compatible with pulmonary vascular disease. The findings emphasize that potential structural reversibility is not synonymous with "operability." Further studies are indicated on the function of the excessively muscularized pulmonary vascular bed of such infants.

Adolescent↗
PubMed1987

The pathology of the early and late stages of primary pulmonary hypertension.

During the course of a case of primary pulmonary hypertension occurring in a 24 year old man lung tissue became available at heart-lung transplantation in 1986 and from a lung biopsy carried out in 1981. In 1986 the sections showed classic plexogenic pulmonary arteriopathy. In 1981 they revealed migration of myofibroblasts into the intima and lumen of pulmonary arteries and arterioles, the identification of the cells being confirmed by electron microscopy. During the five years that the pulmonary vascular pathology progressed to the formation of plexiform lesions there was an increase in the number of bronchiolar endocrine cells that were immunoreactive to bombesin and calcitonin. This study demonstrates that the classic pathogenesis of primary plexogenic pulmonary arteriopathy originates years earlier as a migration of cells of muscular pedigree from the media into the intima of the pulmonary arteries and arterioles.

Adult↗
PubMed1987

Increased sensitivity of the denervated transplanted human heart to isoprenaline both before and after beta-adrenergic blockade.

It is not known whether surgical denervation leads to increased beta-receptor sensitivity after human cardiac transplantation. We assessed cardiac beta-receptor sensitivity by studying the heart rate response to isoprenaline of the denervated donor heart as compared with the innervated recipient heart in eight patients who underwent heterotopic cardiac transplantation and in six patients with orthotopic transplantation. Changes in the donor and recipient hearts seen in these 14 patients were further compared with those seen in 10 normal volunteers. Incremental intravenous infusion of isoprenaline (5, 10, and 15 ng/kg/min) raised heart rate to a greater extent in the donor compared with the recipient hearts in the eight patients who had heterotopic grafts (slopes [beats/min/ng/kg]: donor = +2.26, recipient = +1.59; p less than .01). In addition, the donor hearts of the transplant patients were more sensitive than hearts of the normal volunteers (slopes: donor = +2.26, normal = +0.94; p less than .01). The changes in the two groups of donor hearts were similar (slopes: orthotopic = +2.24, heterotopic = +2.27; NS). The recipient hearts in the patients with heterotopic transplants were more sensitive than the hearts of the normal volunteers (p less than .05), suggesting that the observed differences in isoprenaline sensitivity in the patients with heterotopic grafts were not caused by a decreased sensitivity of the recipient heart. After beta-blockade, the heart rate responses to isoprenaline were attenuated to the same extent in denervated and innervated hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗