Physiology of carotid endarterectomy with ocular pneumoplethysmography

Abstract

Objective documentation of the quantitative physiologic changes associated with the repair of carotid lesions of hemodynamic consequence was obtained in 701 procedures by a comparison of pre- and postoperative ocular pneumoplethysmographic tests (OPG-Gee). The results of repair of severe stenoses depended on the status of the carotid artery opposite the repaired vessel. If the vessel opposite the carotid artery repaired was functionally patent, severely stenosed, or totally occluded, the ocular blood flow improvement on the side of repair was 16%, 27%, and 47%, respectively. Only in the latter group was improvement in ocular blood flow observed on the side opposite the carotid repair (13%). Ocular blood flow, the bulk of which (choroid) is not autoregulated, is a much more sensitive indicator of carotid lesions of hemodynamic consequence than is the autoregulated cerebral blood flow. OPG-Gee is presented as a simple noninvasive test that reliably and reproducibly assesses the quantitative physiologic changes associated with the repair of carotid lesions of hemodynamic consequence. The latter represent 84% of all carotid endarterectomies at this institution.

Hemodynamic Tandem Intracranial Lesions on Magnetic Resonance Angiography in Patients Undergoing Carotid Endarterectomy

“…Notably, our findings are reminiscent of the previous studies using ocular pneumoplethysmography, a noninvasive tool to measure ophthalmic pressure to estimate the flow status of ipsilateral intracranial arteries . Abnormalities on ocular pneumoplethysmography were shown more commonly in patients with severe carotid stenosis or occlusions, and those hemodynamic lesions were usually recovered after carotid endarterectomy; both findings are accordant with our results.…”

Effect of Carotid Artery Stenting on Ophthalmic Artery Flow Patterns

“…Therefore, attention is focused on detecting patients with cranial hypoperfusion. Evidence suggests that carotid bruit (end‐systolic turbulence in the carotid spectral waveform), 27 ophthalmic artery hypotension on ocular pneumoplethysmography, 28 , 29 an ophthalmic pulse delay on ocular pneumoplethysmography, 30 and decreased middle cerebral artery systolic velocities 14 are such indicators. Ophthalmic artery flow, which appears to be influenced by the ipsilateral grade of internal carotid artery stenosis and symptom status, may prove to be such an indicator as well.…”

“…Statistical analysis showed that the ophthalmic artery flow changes after stenting were not statistically different in this group of patients compared to patients with a patent contralateral internal carotid artery. In the study by Gee et al, 28 which studied pre‐ and post‐ocular blood flow in 701 carotid endarterectomy cases using ocular pneumoplethysmography, 27% and 47% improvements on the side of the repaired carotid artery were detected when there was severe stenosis (>70%) and total occlusion of the contralateral carotid artery, respectively. This increase was only 16% when the contralateral side was functionally patent 28 .…”

“…In the study by Gee et al, 28 which studied pre‐ and post‐ocular blood flow in 701 carotid endarterectomy cases using ocular pneumoplethysmography, 27% and 47% improvements on the side of the repaired carotid artery were detected when there was severe stenosis (>70%) and total occlusion of the contralateral carotid artery, respectively. This increase was only 16% when the contralateral side was functionally patent 28 . Although a similar increase was present in our study, it was not statistically significant, perhaps because our study group was small or somehow well compensated due to having patent Circle of Willis arteries, or because ophthalmic artery flow is subject to autoregulation, whereas ocular blood flow is not.…”

Diagnosis of carotid artery stenosis with oculopneumoplethysmography alone and in combination with MRA

“…OPG is also advantageous in that it is an objective process less limited by the operator dependence known in CDUS 22. Further, because choroid blood flow, which makes up the bulk of ocular blood flow, is not autoregulated, it enables detection of hemodynamically significant lesions in a manner more sensitive than autoregulated cerebral blood flow assessable via transcranial Doppler ultrasound 23. However, a limitation is that OPG does not provide information regarding the morphologic characteristics of carotid plaques, which may have prognostic implications regarding likelihood of stroke, although this remains unproven 24,25…”