Search

Objective: To determine the effects of a small dose of beta blocker on neurohumoral and cardiopulmonary responses after cardiac transplantation., Background: Cardiac transplant recipients have a reduced exercise capacity and abnormal cardiovascular responses to exercise. The sympathoadrenal response to exercise has been shown to be abnormal with high venous noradrenaline. The effect of beta blockade on these neurohumoral mechanisms has not been defined., Methods: 10 non-rejecting cardiac transplant recipients were studied. Patients carried out graded exercise to a symptom limited maximum. Blood samples were taken during exercise. Concentrations of noradrenaline, adrenaline, and atrial natriuretic peptide and plasma renin activity were measured. The next day, the exercise and sampling procedure were repeated after an oral dose of propranolol (40 mg)., Results: Patients tolerated exercise poorly after beta blockade, which was reflected in the maximum workload reached. Heart rate and blood pressure were significantly higher at rest and during exercise before beta blockade. Although there was no significant difference when resting, mean (SEM) noradrenaline concentrations during peak exercise were higher after beta blockade (16.2 (2) v 23.6 (2.9) nmol/l, p = 0.001). Adrenaline concentrations at peak exercise were also greater after beta blockade (0.89 (0.31) v 1.18 (0.38) nmol/l, p = 0.055). Atrial natriuretic peptide concentrations tended to be higher after beta blockade (118.75 (50.2) v 169.79 (39.3) pmol/l, p = 0.36). There was no significant change in plasma renin activity., Conclusions: A small oral dose of a competitive beta blocker such as propranolol has an adverse effect on exercise tolerance and cardiovascular response to exercise in cardiac transplant recipients. There are also increased concentrations of circulating noradrenaline and therefore, sympathetic activity during exercise. beta blockers should be used with caution in cardiac transplant recipients.

The occurrence of isolated persistent ductus arteriosus in three generations of one family with surgical correction is described. The high incidence of the malformation in this family suggests autosomal dominant inheritance rather than a polygenic mode of inheritance.

The exercise capacity and cardiopulmonary response to progressive dynamic exercise of eight healthy recipients of heart-lung transplants were compared with those of matched recipients of orthotopic cardiac transplants and normal controls. In both transplant groups the maximum workloads were lower than that in the normal group. The transplant recipients had higher pre-exercise heart rates and lower maximum heart rates than the normal controls. Ventilation during submaximal exercise was similar in the heart transplant group and the controls. The heart-lung group had an increased ventilatory response associated with lower end tidal carbon dioxide concentrations. Exercise capacity after combined heart-lung transplantation is similar to that after cardiac transplantation. Transplant recipients have an abnormal heart rate response during exercise related to cardiac denervation. The altered ventilatory response in heart-lung recipients may be the result of pulmonary denervation.

The mechanical efficiency of left ventricular contraction and relaxation, the asynchrony of the onset of left ventricular relaxation, the time constant of left ventricular isovolumic pressure decay, and left ventricular chamber and myocardial stiffness were analysed in 32 patients after cardiac (24) and heart-lung transplantation (8). After cardiac transplantation left ventricular myocardial stiffness was increased and a mild degree of incoordinate contraction and relaxation was seen. In contrast, after heart-lung transplantation diastolic function was almost normal. Impairment of passive diastolic properties was significantly related to the ischaemic time of the donor heart and the donor's age. The index of left ventricular asynchrony was related to the ischaemic time and the recipient's age. The interval between transplantation and study did not influence the number of rejection episodes. This study confirms the presence of diastolic dysfunction after cardiac transplantation. Impairment of diastolic function seems to be related to the ischaemic time of the donor heart and to a mismatch between the size of the donor heart and the recipient's needs.