Takashi Kutsuzawa

Cerebrovascular CO2 reactivity in normotensive and hypertensive man.

Cerebrovascular reactivity to CO2 inhalation and voluntary hyperventilation was studied in seven normotensive subjects and nine hypertensive patients without clinical or angiographical signs of arteriosclerosis. Cerebral blood flow (CBF) was measured by the intracarotid 133Xe clearance method and calculated as the initial slope index. Three to five CBF measurements were made in each patient in the Paco2 range of 20 to 55 mm Hg. No difference was observed in reactivity between hypertensive and normotensive patients, either during CO, inhalation or during hyperventilation. The shape of the CBF:Paco2 curve suggested a decrease in reactivity below a Paco2 of 30 to 35 mm Hg in both groups. Above a Paco2 of 35 mm Hg, exponential regression analysis yielded a mean reactivity of 6 ± 2%, whereas below a Paco2 of 30 mm Hg it was about 2%. The rise in CBF during CO2 inhalation was not influenced by the intravenous infusion of a small dose of trimethaphan which blocked the concomitant rise in blood pressure.

Regional Cerebral Blood Flow in Patients With Hypertensive Intracerebral Hemorrhage

Regional cerebral blood flow was measured by 183Xe clearance method in 44 patients with hypertensive intracerebral hemorrhage (HIH) within three weeks from attack. Mean CBF in cases with the more disturbed consciousness was the lower value. There was no definite relationship between mean CBF and the duration from last stroke to measurement. In 44 cases, 35 showed hematoma of so-called “lateral type” and nine showed a “mesial type.” There was no difference of mean CBF between these two groups. In the group with lateral-type hematoma, 14 cases were thought to show large space-occupying signs, and their mean CBF was significantly lower than that of the other 21 cases. In 16 cases, relative hyperemic regions were observed in both the focal and nonfocal areas. In seven cases, relative ischemic regions were frequently in nonfocus rather than focus. Response of hyperemic region to carbon dioxide was good in seven and poor in three regions in focal area, and was good in eight and poor in one region in nonfocal area. Reactivity of ischemic region to 5% CO2 inhalation was good in three and poor in zero regions in focus, and was good in three and poor in two regions in nonfocus. Early venous filling (EVF) was observed in 13 cases and all of them were with lateral-type hematomas. Only four out of 13 cases showed good correlation between angiographical findings and cerebral circulation.

Intracerebral leakage of contrast medium in apoplexy

Abstract Forty-four angiograms, which were performed within three weeks of the onset of hypertensive cerebral haemorrhage, have been reviewed. Leakage of contrast material from cerebral vessels into haematoma was observed in five cases in which cerebral angiography was performed within a few hours after the apoplectic attack. It appears reasonable to presume that the shorter the interval between the onset of the haemorrhage and the angiography, the higher the incidence of extravasation of contrast into the haematoma.

Effects of Blood Gases on the Pressure-Flow Relationships in Canine Cerebral Circulation

The effects of the arterial oxygen saturation and carbon dioxide pressure on the pressure-flow relationships in cerebral circulation were studied in 22 dogs. The cerebral blood flow was observed with stepwise lowering of the systemic arterial blood pressure by controlled bleeding in normoxic normocapnic, normoxic hypocapnic, normoxic hypercapnic, hypoxic hypocapnic and hypoxic normocapnic animals. The autoregulation of cerebral blood flow occurred in the animals in which the arterial oxygen saturation and carbon dioxide pressure were above 90%, and between 20 and 46 mm Hg, respectively. When the arterial oxygen saturation and carbon dioxide pressure were maintained between 17% and 40%, and 34 and 47.5 mm Hg, or above 92%, and between 65 and 82 mm Hg, respectively, almost complete loss of autoregulation was observed. However, autoregulation revived in breathing air at about 30 minutes after autoregulation had been lost during severe hypoxia or hypercapnia, which was induced for about 30 minutes. This suggests that a hypoxic or hypercapnic situation for about 30 minutes does not irreversibly damage the autoregulatory mechanism.

Lactate in the Cerebrospinal Fluid and Pressure-Flow Relationships in Canine Cerebral Circulation

In 11 dogs, lactate and pH in the cerebrospinal fluid and in the arterial and the venous blood were measured during stepwise reductions of the arterial blood pressure by controlled bleeding. Increase in lactate and decrease in pH of the cerebrospinal fluid occurred with lowering of the mean arterial blood pressure even within the pressure ranges of 110 to 50 mm Hg, where autoregulation was fairly observed. Reductions of the blood pressure by 20 to 40 mm Hg led to a significant increase in lactate, and reductions by 60 mm Hg led to a significant decrease in pH of the cerebrospinal fluid. The relation of decrease in pH and increase in lactate was linear, suggesting that lactacidosis occurred. In the arterial and the venous blood, a marked increase in lactate and decrease in pH also were observed. Lactate concentrations of the cerebral venous blood were significantly higher than those of the arterial blood until the arterial blood pressure had been reduced below 70 mm Hg. Therefore, it was suggested that increase in lactate of the cerebrospinal fluid might be attributed solely to increase in lactate of the brain tissue, so far as the blood pressure was not lowered below 70 mm Hg at least. The possibility of participation of the cerebrospinal fluid lactacidosis in autoregulation of the cerebral blood flow was discussed.

Risk Factor of Cerebral Arteriosclerosis Studied by Cerebral Angiography

1969年より1974年の5年間に種々の愁訴にて脳血管撮影を施行されながら, 動脈硬化以外の器質的病変を指摘できなかった315例を対象に年齢・血圧・血清総コレステロール値と脳動脈硬化所見との関連を検討した. 脳動脈硬化所見は頚動脈撮影にて造影される動脈系を頭蓋外頚動脈・頭蓋内主幹動脈・頭蓋内小動脈の3部位に区分し, 狭窄及び管径不同の有無・範囲により動脈硬化の程度を3段階に分けた.1) 頭蓋外頚動脈・頭蓋内主幹動脈・頭蓋内小動脈の各部位で, 当然ながら年齢は動脈硬化の主たる危険因子であることが認められた. 又, 頭蓋内主幹動脈は他の動脈系に比較し, 動脈硬化所見を指摘できる頻度が高く, 動脈硬化の好発部位と考えられた.2) 各動脈系とも高血圧群で動脈硬化がより進行しているといえたが, 年齢別検討で推計学上有意差が得られたのは頭蓋内小動脈との関連を50歳台及び60歳台についてみた場合のみで, 高血圧は特に管径の小さな動脈系の硬化との関連が認められた.3) 高血圧群では血清総コレステロール値の上昇と共に, 頭蓋外頚動脈及び頭蓋内主幹動脈硬化例の頻度は高くなった. 特に頭蓋内主幹動脈の硬化とコレステロール値の関連性は5%の危険率で有意であった. コレステロール値が210mg/dl以上の高血圧例では症例の26.5%が頭蓋内主幹動脈に25%以上の狭窄を合併しており,184mg/dl以下の例に比較し約5倍の頻度に達した. 非高血圧群ではコレステロール値と動脈硬化度との間に明らかな関連を見出すことはできなかった.