Cerebral blood flow autoregulation during orthostatic manoeuvre in patients with permanent cardiac pacemaker

Orthostatic test with passive tilting of the upper body was performed in 28 patients with VVI pacemaker. The changes in BP (Riva-Rocci method), CVR and CBF (impedance technique, REG II) as well as in EEG (automatic spectral analysis) observed after tilting, were compared to those in 20 age-matched controls. While in healthy subjects the autoregulation of the CBF was accomplished through a decrease in CVR and resulted in a moderate but significant increase in CBF, in patients the CVR did not change. This event was estimated as a sign of impaired autoregulation, the CBF remained unchanged most probably on account of the increased diastolic and mean BP. Alpha and beta power spectra in the EEG rose significantly after tilting, the shifts being more pronounced in the controls. In the patients there was an increase in theta activity. Cerebral angiopathy due to "subclinical" brain ischaemia during cardiac rhythm disorders preceding pacemaker implantation was accepted as a mechanism underlying the disturbed autoregulation of the cerebral blood flow. For the occurrence of alterations in orthostatic EEG reactivity, a dyscirculatory encephalopathy has been suspected.