CEREBRAL BLOOD-FLOW RESERVE IN PATIENTS WITH SYNDROME-X

Background Patients with syndrome X frequently show disorders of oesop hageal motility, bronchial reactivity or impaired vasodilator capacity of peripheral vascular beds. For these reasons, it has been suggested that syndrome X may represent a generalized abnormality of vascular a nd non-vascular smooth muscle function, rather than an isolated corona ry problem. Objective To measure the cerebral blood flow and cerebrova scular vasodilator reserve in syndrome X patients and in controls. Met hods We measured the cerebral blood flow and cerebrovascular reserve i n 16 patients with syndrome X [11 women, aged 59.5 +/- 10.8 years (mea n +/- SD)] and in 10 age-matched healthy volunteers. No patients had e vidence of stenoses of carotid and vertebral arteries on Doppler sonog raphy. Cerebral blood flow was measured by the Xe-133 inhalation metho d, using the initial slope index as the cerebral blood flow index. Aft er a baseline measurement, a second cerebral blood flow measurement wa s performed 20 min after administration of 10 mg/kg acetazolamide intr avenously. Acetazolamide is known to be a potent cerebral vasodilator. The percentage increase in cerebral blood flow after acetazolamide ad ministration was considered an index of cerebrovascular vasodilator re serve. Results Under basal conditions, both regional and global cerebr al blood flow were nearly identical in the control group and in the pa tient group (initial slope index 50.2 +/- 3.8 versus 50.3 +/- 6.2, NS) . After acetazolamide administration, the cerebral blood flow increase was 29.0 +/- 14% in the patient group and 29.5 +/- 11% in the control group (NS). Conclusions Our data show that cerebral blood flow and ce rebrovascular vasodilator reserve were preserved in a series of patien ts with syndrome X. These results are not consistent with the hypothes is of a diffuse smooth muscle disorder.