The significance of early postoperative duplex studies following carotid endarterectomy.

This study was conducted to evaluate the significance of duplex ultrasound performed soon after carotid endarterectomy. The records of patients with 150 carotid endarterectomies and postoperative duplex ultrasound within 24 h were reviewed. Eleven (7.3%) had abnormal studies with > or =50% stenosis. Two patients with abnormal studies sustained a perioperative stroke and three patients underwent reoperation for persistent lesions (P<0.0001). Preoperative and postoperative cerebral imaging studies (computed tomography (CT) or magnetic resonance imaging (MRI)) were performed on 114 patients. Seven of these demonstrated areas of infarction and all seven had abnormal duplex ultrasound studies. Twenty-six CT scans were performed with two positive for cerebral infarction in the two patients with clinical stroke. In the 88 MRI studies, five demonstrated small, subcortical focal areas of ischemia, which were clinically silent. The relationship of infarction on postoperative cerebral studies and abnormal postoperative duplex ultrasound was significant (P<0.0001). It was concluded that early postoperative duplex ultrasound studies of > or =50% stenosis demonstrate significant association with postoperative stroke or reoperation, as well as with ischemic changes on brain imaging studies. Earlier detection with intraoperative duplex would probably be more advantageous than postoperative duplex ultrasound.

Cerebral microembolism and ischemic changes associated with carotid endarterectomy.

PURPOSE: The purpose of this study is to characterize microembolic signals (MS) that occur during the various phases of carotid endarterectomy (CEA) and to consider their relationship to postoperative changes on magnetic resonance imaging (MRI). METHODS: This was a retrospective study of 76 patients who underwent 78 carotid endarterectomies at a referral center. Perioperative transcranial Doppler monitoring and MRI were performed before and after CEA. The types of MS that occurred during phases of surgery were analyzed and compared with MRI changes. RESULTS: We observed a clinical stroke in one patient (1.3%) and ipsilateral small areas of silent ischemic change on seven postoperative MRI studies (9.0%). In 95% of CEAs, MS were detected. Only those MS observed in the recovery room that occurred at a rate of more than five per 15 minutes were associated with postoperative MRI ischemic changes (p < 0.0001). CONCLUSIONS: Ischemic changes on MRI after CEA are related to postoperative MS.

Cerebral microembolism and early recurrent cerebral or retinal ischemic events.

BACKGROUND AND PURPOSE: We investigated whether cerebral microembolism as detected by transcranial Doppler ultrasonography (TCD) identifies patients at an increased risk for early, recurrent cerebral or retinal ischemic events. METHODS: Records of consecutive patients examined during a 40-month period in the Neurovascular Laboratory were reviewed for the presence of cerebral microembolism. Of the original 302 patients, 229 with 310 arteries met inclusionary criteria. Follow-up information was obtained from the laboratory's database as well as the hospital records. Microembolus detection studies were performed on TC-2000 or TC-2020 instruments equipped with special software, and criteria established a priori were used for microembolus selection. TCD testing was performed a median interval of 9 days after the initial symptoms of cerebral ischemia. Severity of arterial stenosis was determined by cerebral angiography or noninvasive methods. RESULTS: Microembolic signals were detected more frequently in symptomatic (40/140; 28.6%) than asymptomatic (21/170; 12.4%) arteries (P < .001). Ten recurrent ischemic events occurred during a median follow-up of 8 days after TCD examination, all in the territories of symptomatic arteries. Nine events occurred in the territories of microembolic signal positive arteries (9/61; 14.8%) and one in the territory of a microembolic signal-negative artery (1/249; 0.4%) (P < .00). No association was detected in the subgroup with known cardiac lesions. Microembolic signals were more frequent in arteries with lesions causing 70% or more stenosis or occlusion (26/99; 26.3%) than in those with a degree of stenosis less than 70% (17/126; 13.5%) (P = .016). CONCLUSIONS: In this retrospective study, microembolic signals were more common in the territories of symptomatic arteries and particularly those with severely stenotic lesions. During a short follow-up, recurrent ischemic events were more common along the territories of arteries with TCD-detected microembolism and previous symptoms of cerebral or retinal ischemia.

Collateral flow changes through the anterior communicating artery during carotid endarterectomy.

To evaluate early changes in collateral flow through the anterior communicating artery, 11 patients undergoing carotid endarterectomy were monitored. All had angiographically demonstrated collateral flow towards the hemisphere on the side of surgery. The middle cerebral artery ipsilateral to the operated side and the contralateral anterior cerebral artery were simultaneously insonated with a transcranial Doppler instrument equipped with dual transducers, and flow velocity values were obtained at specific surgical stages. Mean flow velocity in the contralateral anterior cerebral artery's A1 segment increased at clamp placement (p = 0.036), did not change during clamping, and decreased at clamp release (p = 0.004). The rise in velocity occurred within seconds of clamp placement in all patients with an increase, reaching the 10 cm/s threshold within 1 min. No consistent increase was detected after 5 min. A decrease in pulsatility index, indicating a drop in resistance, was detected at clamp placement in the middle cerebral artery on the side of surgery (p = 0.012). The index did not change during clamping, but increased at clamp release (p = 0.002). Our findings indicate that significant changes in anterior communicating artery collateral flow occur during carotid endarterectomy, starting within seconds of carotid artery clamping. These changes are associated with arterial resistance alterations in the territory of the middle cerebral artery on the endarterectomy side. Our observations should be useful to assess intracranial early collateral flow changes in surgical and non-surgical settings.

Cerebral microembolism during carotid endarterectomy.

BACKGROUND: This study was designed to assess the intraoperative risk of cerebral microembolism, as detected by transcranial Doppler ultrasonography, during carotid endarterectomy. PATIENTS AND METHODS: Thirty-six patients (37 procedures) with symptomatic (n = 35) or asymptomatic (n = 2) internal carotid artery origin stenosis(> 50%) were monitored continuously during carotid endarterectomy. Special instrumentation was used to detect high-intensity transient signals (HITS) in the middle cerebral artery on the carotid endarterectomy side. All HITS satisfied a priori established criteria. RESULTS: The incidence of carotid endarterectomies with formed-element HITS increased at clamp release (23/37, P < 0.001) and shunt opening (7/11, P = 0.014), and during wound closure (13/22, P< 0.005) and shunting (5/11, P = 0.046). HITS with air microbubble characteristics were detected at clamp release (22/37, P < 0.001) and shunt opening (5/11, P = 0.025). CONCLUSIONS: HITS do not occur randomly during carotid endarterectomy. Shunting, unclamping, and wound closure are high-risk periods.

Hemodynamic considerations during carotid endarterectomy.

To evaluate the hemodynamic and angiographic characteristics of patients undergoing carotid endarterectomy, we reviewed the medical records, angiograms, transcranial Doppler ultrasound data, and EEGs of 42 consecutive patients having 44 carotid endarterectomies. Significant (p < 0.0002) changes in the peak systolic velocity of the middle cerebral artery ipsilateral to the side of surgery (iMCAFV) occurred with anesthesia, carotid clamping, shunting, and the release of clamps. Thirteen percent of patients with collateral flow toward the side of surgery and 57% of those with flow away from the operated side had a drop in iMCAFV exceeding 50% of the baseline value (p = 0.054); the presence of a <70% ipsilateral internal carotid artery stenosis was also correlated with a similar decrease in iMCAFV (p = 0.01). There was no correlation between systolic blood pressure changes and iMCAFV in patients who were not shunted. This information may be useful in guiding intraoperative decision-making.

Atrial myxoma with remote metastasis: case report and review of the literature.

The occurrence of a metastatic atrial myxoma after complete resection of the intracardiac lesion is rare. We treated a 66-year-old man who 13 years earlier had undergone resection of a left atrial myxoma, which had been diagnosed during a work-up of symptomatic cerebellar infarcts. He initially had a painless nonpulsatile mass near the radial artery. Surgery was performed to confirm the presumptive diagnosis of calcified ganglion, and subsequently he was found to have a pseudoaneurysm. The pathologic examination identified the tissue as myxoma. The results of echocardiography and cardiac magnetic resonance imaging failed to reveal any residual or new intracardiac tumor. The patient subsequently experienced swelling of the right leg and was found to have a 6 x 10 cm mass in the medial portion of his proximal thigh. At exploration this mass was found to extend from the profunda femoris artery, and it also compressed the femoral vein. Pathologic evaluation based on histologic and electron microscopic features of this lesion confirmed this lesion to be myxoma. Review of the literature reveals that metastatic atrial myxoma is a rare lesion, and such a delayed occurrence after resection of the cardiac lesion has been infrequently reported. This suggests that patients with atrial myxoma may be at risk for the appearance of intravascular metastatic tumor long after resection of their original intracardiac tumor.

Cerebrovascular hemodynamic changes associated with carotid endarterectomy.

To evaluate the effect of carotid surgery on the cerebral circulation, transcranial Doppler sonography and ocular pneumoplethysmography were performed on 36 patients who underwent unilateral carotid endarterectomy. Ocular pneumoplethysmography and transcranial Doppler sonography tests were performed within a week before and after operation, and transcranial Doppler sonography was repeated greater than or equal to 30 days after operation. Middle and anterior cerebral arteries were insonated bilaterally, and flow velocities ipsilateral (iMCAFV or iACAFV) and contralateral (cMCAFV or cACAFV) to the side of surgery were recorded. The iMCAFV and iACAFV increased significantly in the immediate postoperative period, and the iMCAFV remained elevated on the second follow-up study. Patients with greater than or equal to 75% ipsilateral carotid stenosis (N = 23) had increased iMCAFV, iACAFV, and decreased cACAFV after operation, whereas those with less than 75% stenosis (N = 13) had no significant transcranial Doppler sonography changes. Those with greater than or equal to 75% contralateral carotid stenosis (N = 17) had significant increases in iMCAFV, cMCAFV, and iACAFV after operation, whereas those with less than 75% contralateral carotid stenosis had no significant transcranial Doppler sonography changes. A subset of patients (N = 13) did not increase iMCAFV after surgery. The ocular pneumoplethysmography changes were significantly different in both groups when preoperative and postoperative values were compared. We conclude that carotid endarterectomy can cause lasting cerebral hemodynamic changes, but that its effects are not uniform among all patients.

Traumatic popliteal artery pseudoaneurysms: case report and review of the literature.

Traumatic pseudoaneurysms of the popliteal artery are an uncommon late complication of arterial injury. Although reviewed extensively in wartime, they occur less frequently in civilian trauma and have accordingly been less frequently studied. A case report of a traumatic popliteal artery pseudoaneurysm and review of the literature are presented.

Combined transluminal angioplasty and infrainguinal reconstruction in multilevel atherosclerotic disease.

Patients with multilevel atherosclerotic disease represent a difficult surgical challenge. This report is a retrospective review of 46 patients who were treated using a combination of iliac transluminal angioplasty and infrainguinal reconstruction. There were 42 male and 4 female patients with an average age of 62 years (range: 40 to 74 years). Follow-up ranged from 1 month to 10 years (mean: 27.3 months). These patients had multiple health problems typical of patients with peripheral vascular disease, including coronary artery disease (67%), hypertension (61%), and diabetes mellitus (42%); 80% of the patients were smokers. Forty-one patients were treated for rest pain and/or tissue loss, while five were treated for incapacitating claudication. Forty-three patients had a combination of angioplasty and distal bypass, while 3 patients had a form of femoral endarterectomy. Iliac artery pressure gradients were reduced from 35.4 +/- 4 mm Hg preangioplasty to 0.6 +/- 0.3 mm Hg postangioplasty. The procedures were well tolerated with no mortality and four serious complications. Vascular laboratory studies showed an improvement in the mean ankle-brachial index from 0.35 +/- 0.03 preoperatively to 0.71 +/- 0.04 postoperatively (p less than 0.05). Life-table analysis revealed a 72% 5-year primary patency rate, with a 93% 5-year limb salvage. Eight patients required a secondary procedure to maintain limb salvage. Five patients underwent amputation, three due to early graft thrombosis and two due to late graft failure. We conclude that combined iliac angioplasty and infrainguinal reconstruction is a safe and effective method for managing the patient with severe multilevel atherosclerotic disease.

Correlation of transcranial Doppler and noninvasive tests with angiography in the evaluation of extracranial carotid disease.

To evaluate the usefulness of transcranial Doppler sonography in determining severity of extracranial carotid disease, we compared transcranial Doppler, ocular pneumoplethysmography, Doppler spectral analysis, and duplex scanning data to information derived from cerebral angiography. Fifty-one consecutive patients with unilateral extracranial internal carotid artery stenosis or occlusion were selected. Transcranial Doppler indexes included the peak systolic flow velocity in the middle cerebral artery ipsilateral to the stenosed internal carotid artery (iMCAFV), the difference between the peak systolic flow velocities in the middle cerebral artery ipsilateral and contralateral to the stenosed internal carotid artery (dMCAFV), and the peak systolic flow velocity in the anterior cerebral artery contralateral to the stenosed internal carotid artery (cACAFV). The minimal residual lumen determined angiographically was used as the index of internal carotid artery stenosis. Linear regression analysis with minimal residual lumen as the dependent variable and transcranial Doppler and noninvasive tests as independent variables showed the following correlation coefficients: (1) dMCAFV and cACAFV, R2 = 0.3170; (2) ocular pneumoplethysmography, R2 = 0.4798; (3) dMCAFV, cACAFV, delta ocular pneumoplethysmography, duplex scanning, and spectral analysis R2 = 0.6382; (4) ocular pneumoplethysmography, duplex scanning, and spectral analysis, R2 = 0.6491; (5) iMCAFV, no association. These results were supported by sensitivity and specificity as well as bivariate analysis. We conclude that transcranial Doppler did not significantly add to the information obtained by our noninvasive battery of tests in the evaluation of unilateral extracranial carotid disease.

Quantitative analysis of anastomotic intimal hyperplasia in paired Dacron and PTFE grafts.

The purpose of this investigation was to compare and contrast the occurrence and progression of anastomotic intimal hyperplasia in two commonly used prosthetic arterial grafts. Twenty paired carotid artery interposition grafts of Dacron and PTFE (polytetrafluoroethylene) were implanted in a canine model. The grafts were electively removed at intervals from one week to seven months or at the time of thrombosis. Areas of hyperplastic growth were determined at each anastomosis using a quantitative histologic technique. The number of grafts quantitatively evaluated was 16 Dacron and 12 PTFE, excluding all thrombosed grafts. In both materials, hyperplasia occurred to a significantly greater degree at the distal or downstream anastomosis as compared with the proximal or upstream anastomosis (Dacron P less than 0.001, PTFE P less than 0.05). Quantitative and qualitative evaluation of these two commonly used but different arterial grafts did not demonstrate a significant difference in the occurrence of anastomotic hyperplasia.

Interactive videodisc as an instructional tool in medical education.

At a time when medical educators are actively revising the undergraduate medical school curriculum to make it more responsive to exigencies of the 21st century, the use of interactive videodisc technology may well prove to be a significant addition. Using interactive videodisc technology may be instrumental in reducing the amount of a large lecture didactic learning and improving small group problem-solving sessions that better synthesize factual knowledge. It also provides important and valuable exposure to varieties of computer technology that play an increasingly important role in training and medical practice.

The use of arm veins for infrainguinal bypass in end-stage peripheral vascular disease.

Thirty-six infrainguinal bypass grafts were performed in 33 patients with the use of autologous arm vein. Indications for operation were ischemic rest pain or tissue loss in all patients. The average age of the patients was 70.0 years-27% were diabetic and 66% were smokers. Sixty-five percent of the grafts were performed as secondary reconstructions. Follow-up ranged from three weeks to six years, with a mean of 12.1 months. Life-table primary and secondary patencies for all grafts are 73% and 82% at one year, respectively. Simple (noncomposite) arm vein grafts had primary and secondary patencies of 75% and 85%, respectively. The limb salvage rate was 86%. No grafts required thrombectomy for early occlusion (less than 30 days), and no graft failures have occurred beyond nine months (n = 18). Arm vein bypass grafts demonstrate excellent patency rates and provide the preferred conduit in the absence of autologous saphenous vein.

Complications of caval interruption by Greenfield filter in quadriplegics.

Patients with acutely injured spinal cords are thought to be at increased risk for thromboembolic disease and often have contraindications to anticoagulation therapy. From 1981 to 1986, 13 patients with quadriplegia at the New England Regional Model Spinal Cord Injury Center had caval interruption with a Greenfield filter. Twelve patients had deep venous thrombosis documented by venogram results and one had pulmonary embolism documented by arteriogram results. "Quad cough" chest physical therapy was required for mobilization of pulmonary secretions in nine patients. Follow-up abdominal x-ray results revealed significant abnormalities referrable to the filter in five patients having undergone "quad cough" therapy. Four patients had distal migration of the filter; three of the four had deformation of the filter. Laparotomy for bowel perforation was required in two of these patients. Quadriplegia requiring vigorous chest physical therapy ("quad cough") for pulmonary toilet may be a contraindication to caval interruption by Greenfield filter. Alternative techniques in the management of patients with quadriplegia and pulmonary compromise must be considered.

Effect of inflow and outflow sites on the results of tibioperoneal vein grafts.

We have reviewed our experience with the tibial vessel bypass operation and have found the overall patency and limb salvage rates to be acceptable. Patients were divided into two groups based on the site of the proximal anastomosis. In Group I, the proximal anastomosis was at the common femoral artery and in Group II, the proximal anastomosis was at the distal superficial femoral artery or the popliteal artery. The patients in the two groups were similar with regard to indications for operation, age, and sex. However, in Group I, 35 percent of the patients were diabetic and in Group II, 74 percent of the patients were diabetic. In the Group I patients, the 72 month graft patency rate was 65 percent with a limb salvage rate of 75 percent. In the Group II patients, the 72 month patency rate was 81 percent with a limb salvage rate of 89 percent. Some possible explanations for this slightly better result in Group II patients are discussed. All tibial bypasses were divided into three groups based on the recipient tibial artery. Analysis revealed that the 72 month patency rates were as follows: the anterior tibial artery 63 percent, the posterior tibial artery 81 percent, and the peroneal artery 80 percent. These differences were not significant but indicate, as others have recently pointed out, that the peroneal artery is indeed an acceptable recipient artery for tibial bypass surgery.

Management of the contused arterial segment.

When a contused arterial segment is found at surgical exploration and interposition graft is required, we propose a method of repair in which the posterior wall is not completely divided. This prevents retraction of the arterial ends and eliminates tension on the anastomosis.

Successful vein bypass in patients with an ischemic limb and a palpable popliteal pulse.

Patients presenting with an ischemic foot who have a palpable popliteal pulse have not always been considered to be suitable candidates for arterial reconstruction. Since 1976, 32 distal bypasses were performed in 30 such patients, 77% of whom were diabetic. Proximal anastomoses were from the distal superficial femoral or popliteal artery. Autologous vein was used in all cases. There were six graft failures, all of which occurred within eight months. Three failures, which all occurred within the first month, required below-the-knee amputation. Using life-table analysis, the one- and three-year patency rates were both 79%. One- and three-year limb-salvage rates were 89% and 82%, respectively. We conclude that the results of distal vein graft reconstruction originating from the superficial femoral or popliteal artery are comparable with those of any group of patients with arterial occlusive disease of a lower extremity.

The preoperative angiogram as a predictor of peripheral vascular runoff.

The preoperative angiogram is widely used as a means of assessing peripheral vascular runoff before bypass grafting, but the correlation between preoperative angiographic findings and actual measurements of peripheral vascular resistance has not been adequately examined. To test this correlation, we first devised a simple technique for measuring peripheral resistance and validated it in five dogs. Increases in peripheral resistance were artificially produced by temporarily occluding either the deep or superficial femoral artery or by intravenous administration of phenylephrine hydrochloride, a vasoconstrictor. In each instance, significant increases in resistance could be measured. We then used a similar technique to measure resistance in 23 patients undergoing peripheral bypass surgery. In addition, preoperative angiograms for these 23 patients were independently scored by four readers as 0, 1, 2, or 3 based on the number of patent vessels seen below the knee. Variations in scoring from reader to reader suggested that the present criteria for grading angiograms on this basis are unclear. Moreover, the correlation between angiographic score and measured resistance was poor for three of the four scorers (-0.21 to -0.29, p greater than 0.05). The angiographic scores of one reader, however, correlated reasonably well with the peripheral resistance measured at surgery (-0.59, p = 0.01). These findings demonstrate that current criteria for grading the preoperative angiogram are not sufficiently standardized to reliably predict runoff from a preoperative angiogram. However, these findings also suggest that it may be possible to identify angiographic findings that correlate well with changes in measured resistance.