Effect of removal of phaeochromocytoma on diurnal variability of blood pressure, heart rhythm and excretion of catecholamines.

Ambulatory 24 hour blood pressure and ECG monitoring with simultaneous estimation of the urinary excretion of noradrenaline and adrenaline were performed in seven patients with phaeochromocytoma, before and after removal of the tumour. Mean blood pressure during eight 3-hour periods, mean heart rate, and noradrenaline and adrenaline excretion during four 6-hour periods were estimated. Mean blood pressure before surgery did not show any significant circadian changes. After surgery both systolic and diastolic blood pressures were significantly lower at night than in the daytime periods. In contrast, mean heart rate before surgery was significantly lower at night than in the morning, and this relationship was greater after surgery. Ventricular arrhythmias during 24 hour monitoring were noted in three patients before and in six after surgery. These findings suggest that profound disturbances of autonomic blood pressure regulation improve after removal of phaeochromocytoma, and that ventricular arrhythmias, except for paroxysmal symptoms, tend to be less frequent before than after surgery.