Cortical blood flow during extracranial-intracranial bypass surgery.

Abstract

SUMMARY Cortical Mood flow was evaluated at the time of surgery with a thermal diffusion flow probe in 25 extracranial-intracranial bypass operations. The procedures were performed 14 times for carotid occlusion, 6 times for inaccessible carotid stenosis, on 3 occasions for middle cerebral occlusion, once for basilar occlusion and once for middle cerebral stenosis. Fifty-seven different cortical regions were evaluated before and after completion of the anastomosis.During temporary occlusion of the cortical vessel, no significant changes in cortical blood flow were identified. The mean flow pre-bypass was 58 ml/100 g/min and postbypass was 66. This was a significant difference. When Initial ischemic areas were evaluated, flows increased from 36 ml/100 g/min to 52 ml/100 g/ min. These postbypass flows were statistically different than the flow values in the nonischemic areas of 75 ml/100 g/min. Blood pressure and arterial carbon dioxide tension did not vary significantly.Extracranial-intracranial bypass increases cortical flow in ischemic areas although this does not bring the flow into the normal range. Stroke Vol 15, No 5, 1984 THE RATIONALE for extracranial-intracranial (EC-IC) bypass is to provide an additional conduit into the vascular bed in order to improve blood flow in ischemic regions. Pre-and postoperative cerebral blood flow (CBF) studies have shown increased flow.

Local cerebral hemodynamics after superficial temporal artery-middle cerebral artery bypass in patients with symptomatic carotid occlusions

“…In the group of patients with chronic oligemia, the blood flow in the cortical artery was close to normal values (17–25 cm/s) [Figure 3e and f]. [419] No impact of the initial degree of perfusion deficit on the value of blood flow in the diastole was detected.…”

“…According to the results of flowmetry in the recipient artery in patients with chronic cerebral ischemia, the value of blood flow ranged from 4.8 to 12.1 ml/min, averaging 8.9 ± 2.7 ml/min (blood flow in the M4 segment of the MCA normally is from 12 to 18 ml/min). [419] The value of the blood flow significantly differed depending on the initial perfusion deficit. In patients with gross cerebrovascular insufficiency (group 1), the VBF was the smallest and amounted to only 6.7 ± 1.2 ml/min.…”

“…In this regard, studies of local hemodynamics are of great theoretical and practical interest, as evidenced by a series of actual works devoted to this problem. [45678]…”

“…The obtained data correspond to the results of blood flow measurements in patients with signs of poor perfusion selected for surgery based on isotopic diagnostic methods - the average VBF in the cortical artery in them was 4.4 ml/min with an average linear blood flow rate of 9–15 cm/s. [45678]…”

Guidelines and Recommendations for Perfusion Imaging in Cerebral Ischemia

“…CBF of less than 10 mL/100 g of tissue per minute cannot be tolerated beyond a few minutes before infarction occurs, but between 10 and 20 mL · 100 g Ϫ1 · min Ϫ1 , cell death requires many minutes to hours. [21][22][23][24][25][26][27][28][29][30] Theoretically, tissues with flow values in this intermediate zone might be salvaged if flow restoration occurred quickly, either spontaneously by clot fragmentation and dissolution 31,32 or by therapeutic means such as arterial thrombolysis. While some tissues might be dead at the core of the ischemic process, the more peripheral tissues (the "penumbra") might still be salvageable.…”