SPECT Evaluation of Cerebral Perfusion in Uncomplicated Essential Hypertensives and Effects of Enalapril

A semiquantitative evaluation of regional cerebral blood flow was performed by means of single photon emission computed tomography and 99mTc-hexa-methylpropyleneamine oxime in 25 neurologically asymptomatic patients with essential hypertension and in 10 normotensive controls. Mean flow velocities and pulsatility indexes of intracranial arteries and the vasomotor reactivity of the middle cerebral artery after hyperventilation were assessed by means of transcranial Doppler sonography (TCD). The pattern of cerebral perfusion in hypertensive patients was similar to that of normotensive controls. However, the semiquantitative examination of the CBF flow maps revealed significantly different frontal, temporal and occipital asymmetry indexes in hypertensive patients, as an expression of disturbed perfusion. TCD did not reveal any significant difference in flow velocities between hypertensives and normotensive controls. In 10 randomly selected hypertensive patients the study was repeated after a 4-week oral treatment with the angiotensin-converting enzyme (ACE) inhibitor enalapril. Blood pressure fell significantly without any decrease in cerebral perfusion. The basal asymmetry index was also unaffected, confirming the absence of any steal effect. Thus, there are indications that focal hypoperfusion is a frequent finding among neurologically normal essential hypertensives and that the ACE inhibitor enalapril does not negatively affect cerebral blood flow in the asymptomatic essential hypertensive patients.