Changes in cerebral blood flow in patients with severe congestive cardiac failure before and after captopril treatment.

The intravenous 133xenon injection method was used to estimate global cerebral blood flow before and after treatment with captopril in nine patients with severe heart failure. The pretreatment mean blood pressure was 94.9 mm Hg (S.D. 13.9) and fell to 85.1 mm Hg (S.D. 18.1) after treatment with captopril for between four and 15 days. The cerebral blood flow before captopril was 61.1 ml/100 g per minute (S.D. 6.9), which was less than the value of 75.8 ml/100 g per minute found in control subjects. After treatment with captopril the cerebral blood flow increased to 73.8 ml/100 g per minute (S.D. 11.8, p less than 0.01). The fraction of carbon dioxide in the expired air was not significantly different in the two studies (4.1 +/- 0.88 versus 3.97 +/- 0.65). It is concluded that cerebral blood flow is reduced in severe heart failure and can be restored by treatment with captopril, but the reasons for the reduced flow and its improvement after converting enzyme inhibition are not known.