Cerebral blood flow and calcium antagonists in hypertension.

Antihypertensive treatment reduces the risk of ischaemic strokes and cerebral haemorrhage as complications of excessive or long-standing hypertension. However, neurological dysfunction and brain damage may also accompany acute and, under certain conditions, even chronic antihypertensive treatment. Treatment should therefore be instituted restrictively and cautiously, with special regard to the action of antihypertensive drugs on cerebral perfusion in patients with an increased risk for treatment-induced cerebral ischaemic complications, e.g. patients with hypertensive encephalopathy, patients with autonomic dysfunction or elderly patients with suspected sclerotic stenosis of cerebral or neck arteries. The present study is a review of the structural and functional lesions of cerebral vessels observed in acute and chronic hypertension, together with the effects of antihypertensive drugs on cerebral blood flow. Calcium channel blockers such as nifedipine, nitrendipine and verapamil may have advantages as first-line drugs in the treatment of patients with an elevated risk for cerebral hypoperfusion, because of their selective action on vasoconstricted vessels and their differential effects in different regional vascular beds. The particular efficacy of calcium antagonists in acute antihypertensive treatment, with a significant increase in cerebral blood flow in the case of nifedipine, and also in chronic antihypertensive therapy without decreasing cerebral blood flow, may change the traditional management of hypertensive emergencies, as well as of other patients at risk of treatment-induced complications.