The collateral hemispheric systolic pressure.

Satisfactory calibrated BP tracings were obtained during 385 (85%) of 455 carotid endarterectomies. The pressures were measured from the distal common carotid arteries while the external carotid arteries were clamp occluded. Continuous recordings were made with and without proximal common carotid clamp occlusion. The two systolic pressures resulting in each patient were plotted as a single point on a graph, with the direct carotid systolic pressure on the abscissa and the back carotid systolic pressure on the ordinate. Formulae of the mean values in 101 of the 385 procedures, in which the opposite carotid systems contained severe stenoses or total occlusions, and the other 284 procedures, in which the opposite carotid systems had no notable lesions, demonstrate that the collateral hemispheric systolic pressure depends on the status of the opposite carotid artery and on the central BP. We derived formulae for these two groups of patients to demarcate the lowest collateral hemispheric systolic pressure adequate for hemispheric integrity during and following prolonged operative carotid occlusion or following permanent interruption of carotid blood flow as a result of thrombosis, ligation, or resection without graft replacement.

Postendarterectomy carotid occlusion.

In a prospective study of 300 carotid endarterectomies, ocular pneumoplethysmography (OPG-Gee) was performed in the recovery room after all procedures. Positive test findings, indicative of occlusion of the repaired vessels, were encountered after 16 (5%) of these procedures, and all 16 patients were completely asymptomatic. Serial test results, without angiographic confirmation, have remained positive in nine. Angiography confirmed the positive test results in three. Immediate reoperation, without angiography, confirmed the positive test findings in four, and normal flow was restored in all four cases. Success of carotid endarterectomy should not be measured by absence of symptoms. Objective documentation of persistent patency is essential. Present policy dictates that if recovery room test results are positive, the patient be returned to the operating room as soon as possible, with no delay for angiography.

Extracranial surgery for the low-flow-endangered brain.

Angiography documented severe (greater than 75%, cross-sectional area) bilateral carotid stenotic or occlusive disease in 60 patients. One third of these patients were thought to have transient ischemic symptoms of low-flow rather than embolic etiology. Preangiographic ocular pneumoplethysmography (OPG-Gee) was obtained in all patients. Postoperative OPG studies were obtained in the 39 patients who underwent unilateral carotid surgery. In seven of the 39 patients who were operated on, bilateral procedures were performed; OPG studies were obtained after the second procedure also. Comparison of the preoperative and postoperative OPG studies provided convincing evidence that the establishment of major carotid inflow should be the primary objective in patients with severe bilateral carotid disease, and that distal extracranial-intracranial reconstruction should be reserved for patients failing to respond to augmented inflow because of deficient collateral vessels.

Spontaneous dissection of internal carotid arteries. Spontaneous resolution documented by serial ocular pneumoplethysmography and angiography.

Spontaneous dissection of the internal carotid artery can appear on an angiogram as a total occlusion of this vessel. This appearance differs from that typical of atherothrombotic occlusion. In four patients with spontaneous dissections of internal carotid arteries, serial ocular pneumoplethysmography demonstrated spontaneous restoration to functional patency. Repeated angiography confirmed the noninvasive testing in all four patients.

Carotid stenosis plus occlusion: endarterectomy or bypass?

In 15 patients with unilateral internal carotid artery occlusion and contralateral internal carotid artery stenosis of pressure significance (75% cross-sectional area or greater), the ocular pneumoplethysmograph (OPG-Gee) has documented bilateral improvement in the ophthalmic systolic pressure in 12/15 patients who underwent endarterectomy of the stenosed carotid artery as the sole operative procedure. External carotid to internal carotid shunt on the side of the internal carotid occlusion need be entertained only in those patients who remain symptomatic on the side of the internal carotid occlusion after contralateral stenosis endarterectomy.

Graft infection or graft reaction?

A perigraft reaction has been described that has been found to be free of infection, with a microscopic picture compatible to an immunologic-like reaction. Varied time intervals between onset of reaction and removal of tissue have allowed for a histopathologic staging. Note is made that four of the five grafts involved were external velour Dacron, with a question remaining as to whether the double velour stimulates an intensified hyperimmune response. Graft replacement by way of new uninvolved plains of tissue has not been necessary. Replacement with polytetrafluoroethylene through the same pathway resulted in prompt healing of wounds with no evidence of recurrent reaction.

Ultrasound of arterial graft surgery complications.

The value of gray scale ultrasound in evaluating primary diseases of the abdominal aorta and peripheral vessels has been well documented. However, only limited attention has been given to complications associated with arterial graft surgery. Twelve patients with a variety of complications are reported. These include 10 anastomotic pseudoaneurysms, one abscess, two "aneurysms" in degenerated graft material, and four serous fluid collections around intact Dacron grafts. The latter two complications are previously unreported.

Carotid endarterectomy shunting. Effectiveness determined by operative ocular pneumoplethysmography.

The theoretical advantages and practical disadvantages of carotid endarterectomy shunting are well known. To assess shunt physiology, we performed operative ocular pneumoplethysmography on six patients before carotid clamping, during carotid clamping, during carotid shunting, and on completion of carotid repair. In each case the shunt functioned, at best, as a vessel with at least a 75% or greater cross-sectional area stenosis. However, in all cases it appreciably elevated the ipsilateral ophthalmic systolic pressure over that noted during carotid clamping. There is no question that carotid shunting provides a margin of safety during prolonged carotid clamping.

Restenosis or occlusion after carotid endarterectomy: a survey with ocular pneumoplethysmography.

One hundred seventy-three carotid endarterectomies in 141 patients operated on during a 12-year period were surveyed both clinically and by ocular pneumoplethysmography (OPG)-Gee. Seventeen (12%) patients had positive OPG examinations. Three arteries (1.7%) demonstrated symptomatic recurrent stenosis in accord with earlier reports. An additional 8.1% of the operated arteries had asymptomatic recurrent stenosis. A total recurrence rate of 9.8% was found. Because of the considerable silent recurrence rate we have found, we recommend annual screening by OPG. Angiography and repeated endarterectomy are then used when appropriate.

Screening for significant carotid stenosis by ocular pneumoplethysmography.

Carotid stenosis is significant when the resulting lumen is 50 per cent or less of the diameter of the vessel distal to the carotid sinus. The ocular pneumoplethysmograph can detect these stenoses with an accuracy of 97 per cent.