Cerebral Hemodynamics during Coronary Artery Bypass Graft Surgery: The Effect of Carotid Stenosis

Abstract

Carotid stenosis is a frequent coexisting condition in patients undergoing coronary artery bypass graft (CABG) surgery. The impact of carotid stenosis on cerebral perfusion is not fully understood. The purpose of this study was to determine the impact of carotid stenosis on cerebral blood flow velocity in patients undergoing CABG. Seventy-three patients undergoing CABG were prospectively recruited and underwent preoperative Duplex carotid ultrasound to evaluate the degree of carotid stenosis. Intraoperatively, transcranial Doppler ultrasound was used to record of the mean flow velocity within the bilateral middle cerebral arteries. Additionally, during the period of cardiopulmonary bypass, regulators of cerebral hemodynamics such as hematocrit, partial pressure of carbon dioxide, and temperature were recorded. The ipsilateral middle cerebral artery mean flow velocity was compared in arteries with and without carotid stenosis using a repeated measures analysis. Seventy-three patients underwent intraoperative monitoring during CABG and 30% (n=22) had carotid stenosis. Overall, MFV rose throughout the duration of CABG including when the patient was on cardiopulmonary bypass. However, there was no significant MFV difference between those arteries with and without stenosis (F=1.2, p=.21). Further analysis during cardiopulmonary bypass, demonstrated that hemodilution and partial pressure of carbon dioxide may play a role in cerebral Contact Author (and reprints): James L. Rudolph, VABHS GRECC (JP-182),

Microemboli are not associated with delirium after coronary artery bypass graft surgery

“…Patients with increased atherosclerosis, measured by carotid stenosis or ascending aortic plaque, are at increased risk for delirium, because atherosclerosis is associated with pre-existing cognitive impairments. 36 Prior work found that carotid stenosis >70% is associated with reduced flow 18 and, thus, reduced ipsilateral microemboli. While intraoperative microemboli, especially particulate emboli, may contribute to the operative stressors, they are unlikely to be the sole cause of delirium or cognitive impairment.…”

“…The study cohort recruitment and flow data have been reported previously. 18 Participants with delirium at baseline, those with inadequate TCD windows, and those who underwent valve replacement/repair or combined CABG/valve were excluded. All patients provided their written informed consent and the study was approved by the human subjects committee.…”

Assessment of cerebral autoregulatory function and inter-hemispheric blood flow in older adults with internal carotid artery stenosis using transcranial Doppler sonography-based measurement of transient hyperemic response after carotid artery compression

“…It has also been proposed that dysregulation of cerebral blood flow regulation in CAS patients may also contribute to perioperative complications during carotid endarterectomy or carotid artery reconstruction surgery [ 5 , 17 , 18 ]. Factors that determine adequate hemodynamic compensation and thereby the clinical consequences of CAS as well as medical and surgical complications of carotid reconstruction surgery likely involve the anatomy of the circle of Willis (CoW) [ 13 , 19 – 31 ], the magnitude of compensatory inter-hemispheric blood flow, and the effectiveness of cerebral microcirculatory blood flow autoregulation [ 10 – 16 , 19 , 20 , 32 – 38 ].…”

Monitoring of cerebral hemodynamics during off-pump coronary artery bypass grafting

“…До конца не ясно, как изменяется МКТ у пациентов со стенотическим пораженим БЦА при операциях КШ без применения ИК [13]. В этих условиях необходимо из-учение особенностей церебрального кровотока и его регу-ляции во время операции КШ без применения ИК.…”