['Abnormal right ventricular function in patients with pulmonary heart disease (PHD) may contribute to their reduced exercise capacity. We have evaluated the effect of subacute dosing with xamoterol, a beta-1 adrenoreceptor partial agonist with inotropic properties, on right ventricular function in patients with PHD.', 'Twelve patients with advanced chronic obstructive pulmonary disease and clinical evidence of PHD received xamoterol 200 mg twice daily or placebo for 7 days in a randomised double-blind crossover study. Right heart krypton-81m radionuclide ventriculography was used to derive right ventricular ejection fraction (RVEF) both at rest and during submaximal exercise, and indices of right ventricular systolic and diastolic function at rest.', 'During treatment with placebo, mean RVEF was 0.53 at rest and was unchanged during exercise. After xamoterol, mean RVEF was 0.55 at rest and increased to 0.59 during exercise. Xamoterol increased right ventricular peak ejection rate from 3.04 to 3.45 EDV.s-1 and mean early diastolic filling rate from 1.00 to 1.20 EDV.s-1.'] Does xamoterol improve right ventricular systolic and diastolic function in pulmonary heart disease?