Intraoperative Duplex Scanning Research Articles

Systematic review of intra-operative duplex scanning during renal transplantation.

A systematic review of the value of intra-operative duplex scanning during renal transplantation was undertaken. Studies assessing intra-operative renal cortical flow in the arcuate vessels with outcomes of ultrasound directed interventions during the initial procedure, delayed graft function, post-operative resistive indices, graft losses and early returns to theatre for graft hypoperfusion were reviewed. PROSPERO registration: (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020203873). Literature searching identified 2069 articles for screening, with 131 reviewed and 12 selected for analysis comprising 5 individual case reports, one case series of 11 patients and 6 non-randomised controlled trials. Studies with similar methodologies were pooled because of the low number of studies and outcomes. Outcomes of interest were not reported for all patients. Intra-operative interventions comprising graft repositioning in 18 (16%) and vascular revision in 2 (2%) were performed in 115 patients undergoing intra-operative scans. There were no graft losses or returns to theatre for graft hypoperfusion (0 of 108 cases) compared to 7 of 71 (10%) without intraoperative scanning (P = 0.003). Three of 8 (38%) patients with high intra-operative resistive indices (RIs) were returned to theatre for hypoperfusion compared to 1 of 110 (1%) patients with normal resistive indices (P = <0.001). Ten of 13 (77%) patients with high RIs had delayed graft function compared to 10 of 40 (25%) with normal RIs (P = 0.001). Despite the absence of randomised controlled trials, and heterogeneous small studies, adverse outcomes were reduced with intra-operative scanning. High intraoperative RIs were predictive of both delayed graft function and return to theatre for hypoperfusion.

Влияние нарушений региональной гемодинамики и микроциркуляции кишечной стенки на возникновение острых перфораций тонкой кишки

Relevance One of the main causes of postoperative diffuse peritonitis (PDP) are acute perforation of the various divisions of the small intestine and failure interintestinal enteroenteroanastomosis. The occurrence of these complications significantly reduces the severity of the patients and contributes to mortality up to 60 – 90%. The purpose of the study To study the influence of hemodynamic mesenteric circulation and microcirculation of the intestinal wall on the occurrence of acute perforation of the small intestine. Materials and methods For registration of normal blood flow values 16 volunteers routinely performed transabdominal ultrasound duplex scanning of the celiac trunk (TC), the superior mesenteric artery (AMS) and its branches (ram). In comparison, 20 patients with PDP duplex scanning of the same pools performed intraoperatively during the first sanation relaparotomy, including 6 before and after intestinal intubation. Subsequently, the dynamics of changes of blood flow in the specified pools in all patients with PDP was carried out with repeated intraoperative ultrasound duplex scanning (IUDS) during 2 or 3 programmed rehabilitation abdomen. The second stage using laser doppler flowmetry intraoperative (ILDF) were determined normal microcirculation wall of the small intestine. For this were examined in 10 patients operated on in a planned way and no signs of peritonitis. In comparison, the same investigation was carried out with 10 patients during the first PDP relaparotomy (including 6 before and after intestinal intubation), and the dynamics during programmed sanations abdomen. Results and their discussion Transabdominal and intraoperative ultrasound duplex scanning visceral abdominal vessels of volunteers and patients with PDP showed that the maximum values of blood flow velocity (Vmax, Vd, TAMAX) in both groups recorded at TC and AMS with a significant reduction of the periphery against the background of increasing peripheral resistance index (RI). When comparing the same levels of blood flow in volunteers and patients with PDP at AMS and ram it was noted a significant decrease significantly peak systolic (Vmax), increase in end-diastolic (Vd) blood flow velocity, TAMAX, as well as reduced RI in patients with PDP. However, the IUDS level branches AMS performed after intestinal intubation in patients with PDP, revealed a significant increase in RI and reduced TAMAX. These changes are interpreted as microcirculation disturbances manifested visual appearance petechial hemorrhages in the intestinal wall overstretched, with a reduction in central hemodynamics during this period due to reperfusion syndrome. In assessing ILDF wall of the small intestine in patients with PDP compared with the volunteers had significant microcirculatory disorders, manifested by reduced microcirculation, standard deviation, performance index microcirculation bypass indicator. In evaluating these parameters in patients with PDP 36 hours during programmed relaparotomy had significantly their growth. At the same time, the analysis of the amplitude - frequency spectrum ILDF performed after intestinal intubation in patients with first relaparotomy in patients with PDP index was decreased with increasing the efficiency of microcirculation index bypass due to an increase of neurogenic and myogenic tone of blood vessels, which indicates a lean microvasculature and worsening of metabolic disorders in the intestinal wall. Conclusion Using IUDS ILDF and visceral arteries in patients with PDP reveals significant violations mesenteric circulation and microcirculation, more pronounced at the level of branches of the AMS. Registration of changes in mesenteric blood flow in patients with PDP after intestinal intubation allows to fix the further deterioration of microcirculatory pool associated with the occurrence of reperfusion syndrome. On the background of the planned sanations abdomen in patients with PDP, along with relief of the inflammatory process, there is significant improvement in the mesenteric circulation and microcirculation. Key words Acute bowel perforation, postoperative peritonitis, microcirculation, intraoperative duplex scanning, intraoperative laser doppler flowmetry

Part One: For the Motion. Completion Angiography Should be Used Routinely Following Carotid Endarterectomy

Part One: For the Motion. Completion Angiography Should be Used Routinely Following Carotid Endarterectomy

Part Two: Against the Motion. Completion Angiography is Unnecessary Following Carotid Endarterectomy

Part Two: Against the Motion. Completion Angiography is Unnecessary Following Carotid Endarterectomy

Iatrogenic injuries of the common femoral artery (CFA) and external iliac artery (EIA) during endograft placement: An underdiagnosed entity

Early limb occlusions following endovascular treatment of aorto-iliac aneurysmal disease is not uncommon (4%-13%). To assess whether the femoral artery entry site could potentially cause this complication, we prospectively evaluated the ipsilateral common femoral artery (CFA) and distal external iliac artery (EIA) with intraoperative duplex scans (IDS). There were 134 patients with infrarenal nonruptured abdominal aorto-iliac aneurysms treated with endografts since 2002 at our institution. Age ranged from 65 to 89 years (mean: 77 +/- 7 years). Aneuryx (n = 41), Zenith (n = 50), and Excluder (n = 43) endografts were used for repair. All procedures were performed via open exposure of the CFA. Introducer diameter varied from 12 mm to 22 mm. All patients underwent IDS of the CFA and distal EIA after repair of the arteriotomies. In 34 patients (25%), we documented intimal dissections causing severe (>70%) stenoses. Of the 271 arteries that were examined, 38 (14%) had abnormal findings that demanded intervention. These were repaired with flap excision, tacking sutures revision, or patch angioplasty (n = 36). Repeat IDS confirmed the adequacy of the repair. No statistical difference was noted if the site of larger introducer sheath and the incidence of flap formation. In addition, 10 small flaps or plaques were visualized but did not create significant stenosis. No differences were noted in the incidence of positive duplex exams between each type graft (P = .4). No early or late iliac limb occlusions were noted. Follow-up of 94% was obtained. Completion arterial duplex scans are helpful in detecting a substantial number of clinically unsuspected technical defects caused by introducer sheaths. Timely diagnosis and repair of these defects may decrease the incidence of early limb occlusion following endograft placement.

Inferior gluteal artery aneurysm with arteriovenous fistula

A 78-year-old woman was referred with a pulsatile mass in the left buttock and pain in the left leg. She also complained of numbness from the left buttock to the posterior thigh. She had a history of pelvic fracture as the result of a traffic accident 2 years earlier. A computed tomography (CT) scan demonstrated a 35-mm 33-mm aneurysm under the gluteus maximus muscle (A), in a location that could cause compression of the sciatic nerve. An arteriogram showed an aneurysm arising from the distal inferior gluteal artery with rapid visualization of the associated vein, indicating an arteriovenous (AV) fistula (B). These findings were confirmed by three-dimensional CT angiography and demonstrated that the AV fistula perfused the left iliac vein and sacral venous plexus (Cover). We judged that surgical resection of the aneurysm and concomitant AV fistula carried a high risk of massive intraoperative bleeding or injury to the adjacent neurologic structures; therefore, we performed an endovascular intervention. A contralateral transfemoral sheath was placed into the left internal iliac artery with selective catheterization of the left inferior gluteal artery. Coil embolization of the inferior gluteal artery was performed via a microcatheter using four 5-mm Vortex coils (Boston Scientific Corp, Natick, Mass). After the artery was successfully embolized and complete angiographic exclusion of the aneurysm was achieved (C), intraoperative duplex scanning showed loss of flow within the aneurysm. Postoperative CT scan confirmed complete thrombosis of the aneurysm. The patient’s postoperative course was uneventful, and her leg symptoms resolved.

Role of Intraoperative Completion Duplex Scan for Diagnosis of Iatrogenic Injuries of the Common Femoral Artery (CFA) and External Iliac Artery (EIA) during Endograft Placement

Objective To assess whether the femoral artery entry site could cause early endograft limb occlusion complication, we prospectively evaluated the ipsilateral common femoral artery (CFA) with intraoperative duplex scans (IDS). Methods Forty-seven patients underwent 41 abdominal aortic and 8 common iliac artery (CIA) aneurysms repair with endografts. All procedures were performed via open exposure of the CFA. All patients underwent IDS of the CFA and distal external iliac artery after repair of the arteriotomies. Results Overall, there were 91 arteries assessed with IDS. Overall incidence of significant lesions requiring repair was 11 of 91 (12%). In 10 arteries (11%) we documented intimal flaps causing severe (&gt;80%) stenoses that required repair. One more patient (1%) had no defects at the repair site, but low CFA peak systolic velocity with ratio 2:1 as compared with the contralateral CFA. Intraoperative abdominal duplex scan revealed a severe stenosis in the ipsilateral CIA that was not observed on the completion arteriogram. In addition, 13 (14%) nonsignificant flaps were visualized. No limb thromboses were noted in this group of patients on follow-up examinations. Conclusions IDS is helpful in detecting clinically unsuspected technical defects of the CFA. Timely diagnosis and repair of these defects may improve early patency of endograft limbs.

The Fate of Unrevised Stenoses in Infrainguinal Autologous Vein Grafts as Detected by Intraoperative Duplex Scanning

Intraoperative infrainguinal autologous vein graft stenoses are common, and some authors advise revision of these stenoses. But the natural history of these lesions is not clear. This study was undertaken to determine the natural history of duplex-detected intraoperative stenoses with a nonrevision policy. Intraoperative duplex scanning was performed in 46 infrainguinal autologous vein bypasses. The surgeon was blinded for the results of the intraoperative duplex scan and no intraoperative graft revision or modification of the routine postoperative protocol was performed after the duplex scan. Intraoperative duplex parameters and patient and bypass characteristics were correlated with the occurrence of an early graft event (occlusion or revision of a patent graft within 6 weeks postoperatively), which was the study's primary endpoint. Early graft event rate was 37% (17/46). PSV ratio and PSV-max were the only parameters with a significant correlation with the occurrence of an early graft event. An intraoperatively measured PSV ratio of > or =3.0 was the best predictor of an early graft failure with a sensitivity of 71% (95% CI: 50-83%) and a specificity of 90% (95% CI: 78-97%). In 12 of the 15 (80%) grafts matching this criterion an early graft event occurred, while only 5 (16%) early graft events occurred in the remaining 31 grafts (ie, a negative predictive value of 84%). When a PSV ratio of > or =3.0 was used as a cutoff value to predict early postoperative graft events, the likelihood ratios for a positive and negative test result were respectively 6.82 (95% CI: 2.23-20.8) and 0.33 (95% CI: 0.16-0.69). Unrevised intraoperative duplex-detected stenoses in infrainguinal autologous vein graft stenoses are a serious threat to early graft patency. The presence of an intraoperatively detected graft stenosis with a PSV ratio > or =3.0 is a strong predictor of early graft failure.

Intraoperative carotid artery duplex scanning in a modern series of 650 consecutive primary endarterectomy procedures

PurposeThromboembolic complications after carotid endarterectomy are frequently associated with technical defects. We analyzed the effect of intraoperative duplex scanning in detection of significant but clinically unsuspected technical defects and residual common carotid artery (CCA) disease as a potential source of postoperative transitory ischemic attack (TIA) and stroke. MethodsFrom April 2000 to April 2003, 650 consecutive primary carotid endarterectomy procedures were performed in 590 patients at a single institution by two vascular surgeons. Patients included 335 men (57%) and 255 women (43%). Indications for surgery were asymptomatic internal carotid artery (ICA) stenosis (≥70%) in 464 patients (71%). All procedures were performed with the patient under general anesthesia, with synthetic patch angioplasty in 644 (99.1%). Major technical defects at intraoperative duplex scanning (>30% luminal internal carotid artery stenosis, free-floating clot, dissection, arterial disruption with pseudoaneurysm) were repaired. CCA residual disease was reported as wall thickness (0.7-4.8 mm; mean, 1.7 ± 0.7) and percent stenosis (16%-67%; mean, 32% ± 8%) in all cases. Postoperative 30-day TIA, stroke, and death rates were analyzed. ResultsThere were no clinically detectable postoperative thromboembolic events in this series. All 15 major defects (2.3%) identified with duplex scanning were successfully revised. These included 7 intimal flaps, 4 free-floating clots, 2 ICA stenoses, 1 ICA pseudoaneurysm, and 1 retrograde CCA dissection. Diameter reduction ranged from 40% to 90% (mean, 67 ± 16%), and peak systolic velocity ranged from 69 to 497 cm/s (mean, 250 ± 121 cm/s). Thirty-one patients (5%) with the highest residual wall thickness (>3mm) in the CCA and 19 (3%) with the highest CCA residual diameter reduction (>50%) did not have postoperative stroke or TIA. Overall postoperative stroke and mortality rates were 0.3% and 0.5%, respectively; combined stroke and mortality rate was 0.8%. One stroke was caused by hyperperfusion, and the other occurred as an extension of a previous cerebral infarct. No patients had TIAs. Two deaths were caused by myocardial infarction, and one death by respiratory insufficiency. ConclusionWe believe intraoperative duplex scanning had a major role in these improved results, because it enabled detection of clinically unsuspected significant lesions. Residual disease in the CCA does not seem to be a harbinger of stroke or TIA.

Intraoperative duplex ultrasonography as an adjunct to technical excellence in 100 consecutive carotid endarterectomies

Purpose To evaluate the relationship of intraoperative duplex ultrasonography (duplex) results to neurologic outcomes and restenosis among patients undergoing carotid endarterectomy (CEA). Methods One hundred consecutive CEAs were performed at a military medical center over 28 months. Prospectively acquired demographics, duplex results, revisions, and surgical outcomes were reviewed. Results Thirty-four percent (34 of 100) of sites were abnormal by completion duplex. Of these, 70% (24 of 34) were B-mode flap type defects located in the common carotid artery (CCA), internal carotid artery (ICA), or external carotid artery (ECA). Twenty-one percent of the defects (7 of 34) were technically unacceptable and immediately revised. Subsequently, 3 perioperative neurologic events occurred, 2 strokes and 1 transient ischemic attack (TIA), all among patients with an identified but unrepaired defect involving the ICA or CCA. This association of unrepaired defect with early stroke or TIA was significant ( P = 0.02). No significant association ( P >0.05) between unrepaired defects and late ipsilateral stroke or TIA or restenosis was identified. Conclusions Intraoperative duplex scanning is a useful adjunct to CEA that can identify correctable mechanical problems. Residual elevated velocities or B-mode flaps 2 mm or greater in the ICA warrant consideration for immediate repair. Findings not requiring revision include flaps <2 mm, as well as isolated ECA defects. Prospectively validated duplex criteria are needed to further define which defects require immediate repair.

Vascular surgical society of great britain and ireland: Re-evaluation of criteria for reoperation in carotid endarterectomy using intraoperative duplex imaging

BACKGROUND: The aim of this study was to compare data obtained during surgery with data collected at 6 weeks after operation to evaluate appropriate criteria for reoperation. METHODS: One hundred and twenty consecutive patients undergoing carotid endarterectomy had duplex scans at operation and 6 weeks later. Neurological evaluation was also documented. RESULTS: Of 96 patients who had a normal intraoperative duplex scan by standard criteria, 91 had normal scans at 6 weeks. One occluded an internal carotid artery (ICA) at 6 weeks with no symptoms. Four had kinks or high-grade contralateral lesions leading to velocity enhancement but no filling defect. All were asymptomatic. Twenty-four patients had abnormal intraoperative scans. Thirteen patients had visible kinking of the ICA or reperfusion hyperaemia; 12 of these patients had normal 6-week scans and one had a mild residual kink but no symptoms. Eleven patients had visible colour-filling defects and significant velocity enhancement. Nine of these were reopened and refashioned. Subsequent duplex imaging was satisfactory in all cases and 6-week scans were normal. One patient had an occluded ICA at operation and developed a dense stroke after operation. Another had residual raised velocities distally which remained at 6 weeks. This patient had no symptoms. CONCLUSION: Intraoperative velocity measurements alone cannot be relied upon as an indication for reoperation. Significant velocity enhancement combined with a visible filling defect appears to represent a satisfactory criterion for reoperation. There were no complications as a result of reoperation. There was no early restenosis in the whole group and there were no neurological sequelae in any patient with a satisfactory scan using the above criteria.

Prediction of early graft failure with intraoperative completion duplex ultrasound scan.

The purpose of this study was to determine intraoperative hemodynamic parameters that predict early failure of infragenicular vein grafts with intraoperative completion duplex ultrasound scan. We reviewed the results of intraoperative duplex scans that were selectively performed after completion of 45 tibial/pedal vein bypass grafts at high risk for failure. Bypass was performed for rest pain (39%) or tissue loss (61%), and 60% of the cases were disadvantaged because of compromised vein quality or poor arterial outflow. A 10-MHz low-profile transducer was used to scan the entire graft at bypass completion. All grafts were determined to be technically adequate (absence of retained valves, arteriovenous fistulas, or localized velocity increases and the presence of bypass-dependent distal pulses). Peak systolic velocity (PSV) and end diastolic velocity (EDV) were also measured at each anastomosis, in the outflow artery and in the proximal and distal portions of each graft. Resistive indices (RI) were calculated at each measurement point (PSV-EDV/PSV). Statistical analysis was performed with unpaired t test, chi(2) test, and multivariate analyses. Twenty infragenicular vein bypass grafts (44%) thrombosed within 12 months. Intraoperative hemodynamic parameters were significantly different between grafts that remained patent or thrombosed. EDV was lower (5 +/- 1 cm/s versus 13 +/- 3 cm/s; P =.02) and RI was higher (0.90 versus 0.81; P <.01) in the proximal portions of grafts that thrombosed within 12 months. Distal EDV was also lower (6 +/- 1 cm/s versus 15 +/- 2 cm/s; P <.01) and distal RI was higher (0.89 versus 0.78; P <.01) in grafts that thrombosed. With multivariate analysis, only low distal EDV was predictive of early graft failure (P <.05). Distal bypass EDV of less than 8 cm/s predicated early graft thrombosis with 76% sensitivity and 75% specificity (positive predictive value, 71%; negative predictive value, 78%). Absence of diastolic flow (EDV of 0 cm/s) predicted early graft failure with 100% specificity and 100% positive predictive value. In this initial experience, low EDV measured with intraoperative duplex scan was associated with early thrombosis of tibial level vein grafts. When such values are observed, measures should be taken to improve graft hemodynamic parameters. Prospective study of infragenicular vein bypass grafts may better define hemodynamic parameters predictive of early graft thrombosis.

Internal carotid artery flow volume measurement and other intraoperative duplex scanning parameters as predictors of stroke after carotid endarterectomy

Intraoperative duplex scanning (IDS) after carotid endarterectomy (CEA) has been shown to reliably identify major defects either by significant changes in peak systolic velocities or by B-mode imaging. To evaluate whether IDS could also predict postoperative strokes in technically flawless CEAs, we analyzed several hemodynamic parameters and correlated them with patient outcome. From March 2000 to February 2001, 226 consecutive primary CEAs were performed in 208 patients (120 men). Of these, 153 lesions were asymptomatic. General anesthesia and synthetic carotid artery patches were used routinely. Intraluminal shunts were used when internal carotid artery (ICA) back-pressures were <50 mm Hg (35% of cases). IDS consisted of B-mode and color-flow imaging and spectral analyses of the common, external, and internal carotid arteries. Volume flows were measured three times, and the mean flow rate was used for this study. The first set of data was analyzed when the twenty-ninth patient had the second immediate postoperative stroke. It was noted that the two patients who had postoperative strokes had mean ICA volume flows (MICAVF) of 48 mL/min and 85 mL/min. Only two additional patients had MICAVF <100 mL/min. The remaining 25 cases had MICAVF ranging from 102 to 299 mL/min, with a mean of 165 +/- 57 mL/min (+/-SD) (P <.02). Although there was a significant correlation between MICAVF and ICA peak systolic velocity (P <.01), the latter was not found to be a significant predictor of postoperative stroke. Moreover, end-diastolic velocities, resistive index, ICA diameter, and ICA back-pressure also did not correlate with neurologic events. These findings led us to change our protocol for patients with MICAVF <100 mL/min. This included a repeat set of volume flow measurements after 15 to 20 minutes, withholding the reversal of heparin, and the liberal use of completion arteriography. Of the following 197 CEAs, 26 (13%) were found to have MICAVF <100 mL/min (range 55 to 99 mL/min; mean 79 +/- 18 mL/min). Of these, five had arteriography that documented spasm of the intracranial portion of the ICA in four and a small-diameter ICA (<2 mm) in one. Except for the five cases, the remaining 21 cases had MICAVF >100 mL/min (range 105 to 158 mL/min, mean 127 +/- 20 mL/min [+/-SD]) on repeat study. Four patients with persistent ICA low flow (70 to 99 mL/min) were treated with postoperative anticoagulation. One of the last 197 patients had a stroke caused by hyperperfusion syndrome 2 weeks after operation. Overall, six of 226 cases (2.7%) required revision on the basis of abnormal B-mode imaging results or peak systolic velocities >150 cm/s. There were two common carotid artery flaps, two ICA stenoses, one ICA flap, and one localized thrombus. All six were successfully revised and had repeat normal IDS study results, and none of these patients had a postoperative stroke. IDS is helpful in identifying residual lesions or defects that may contribute to postoperative neurologic deficits. MICAVF <100 mL/min are suggestive of spasm that could lead to thrombus formation and stroke, particularly in the presence of synthetic patches. We suggest that heparin reversal should not be used unless ICA flow rates are >100 mL/min. ICA spasm is short lived in most patients undergoing CEA.

Intraoperative carotid evaluation.

Intraoperative duplex scanning can identify technical defects and increase the quality of carotid artery repair. We evaluated 100 consecutive carotid operations in 96 patients (60 men and 36 women) from 1995 to 1998. Spectral-derived peak systolic flow velocities (PSV) were graded (PSV < 100 cm/s, normal laminar flow; PSV 100-150 cm/s, mild or moderate flow disturbance; PSV > 150 cm/s, severe flow disturbance). Prospective criteria for intraoperative revision included PSV greater than 150 cm/s, spectral broadening, and B-mode imaging of intimal flaps or intraluminal debris. Preoperative, intraoperative, and 6-week follow-up duplex scan results were analyzed. All patients were evaluated and treated at a single academic institution. All procedures were performed with the patient under general endotracheal anesthesia; 86% underwent shunting and 70% underwent patching. Number and type of revisions, patency of repair, residual and recurrent stenosis, and ipsilateral neurologic events. There were 33 intraoperative duplex studies with abnormal findings. Seven involved the common carotid artery and resulted in intraoperative revision of 5 intimal flaps at the site of the proximal clamp. In 11 patients, incomplete eversion endarterectomy resulted in elevated distal intimal flaps in the external carotid artery that were repaired through a separate arteriotomy. There were 15 abnormalities in the internal carotid artery prompting 5 revisions. Five studies with PSV of 100 to 150 cm/s had no defects on B-mode imaging and were observed without treatment. Five false-positive studies were attributed to increased flow velocity due to contralateral occlusive discase. At 6 weeks' follow-up, 4 of 5 repaired common carotid arteries were normal on duplex scan and 1 had a mild residual stenosis. Ten of the 11 external carotid repairs were patent and 1 was occluded. Four of the 5 internal carotid artery repairs were normal on postoperative evaluation and 1 had a mild residual stenosis. Of the 10 abnormal internal carotid arteries that were observed, 9 were normal on postoperative duplex and 1 had a mild residual stenosis. One perioperative stroke occurred in a patient with a normal, patent carotid repair. Intraoperative duplex evaluation of carotid reconstruction is an efficient, sensitive tool that can detect technical lesions that will jeopardize surgical reconstruction. Interpretive judgment is required because all flow disturbances do not dictate surgical intervention. This technique enables the surgeon to maximize the quality of the arterial reconstruction during carotid artery surgery.

Reply.

The vascular surgery section at Charing Cross Hospital found no benefit from duplex surveillance after carotid endarterectomy in a prospective study of 305 patients studied at frequent (1 week and 3, 6, 9, 12 months) intervals during the first postoperative year and annually thereafter. As stated in their letter, “funds would be better spent elsewhere.” We agree in part with these conclusions and proposed a “rational” surveillance algorithm based on duplex scanning performed at operation, at 4 to 6 weeks after endarterectomy, and thereafter on the basis of carotid disease severity. When enrolled in a stroke prevention program after carotid endarterectomy, most patients do not need intensive duplex scan surveillance, if a policy of operation for high-grade internal carotid artery (ICA) stenosis is adopted. When the intraoperative duplex scan verifies a normal repair, the incidence of restenosis is low, less than 4% by life table analysis at 3 years. Thus approximately 80% of patients with a normal repair site and less than 50% contralateral ICA diameter reduction stenosis can be followed up by clinical examination and a duplex scan at 1- to 2-year intervals. Mr Greenhalgh and coauthors similarly noted in their paper that “restriction of follow-up to patients with >50% stenosis would have reduced to 78% the percentage of patients requiring duplex surveillance, and still identifying 8 of 9 patients who required endarterectomy.” Contralateral >50% ICA stenosis is a lesion with a propensity to progress in severity (approximately 10% incidence per year) and produce stroke or ICA occlusion. In our series, approximately 15% of patients with a normal repair had contralateral >50% stenosis, and duplex surveillance at 6-month intervals was adequate to detect asymptomatic disease progression. The carotid repair with residual or early appearing restenosis is at risk for progression to a high-grade lesion but occurs in less than 5% of patients. It seems prudent to me to evaluate these patients at 6-month intervals by duplex scanning. Duplex surveillance is one component of an effective stroke prevention program for patients after carotid endarterectomy. Control of atherosclerotic risk factors, lipid-lowering therapy, antiplatelet drug administration, and control of hypertension are equally important features of the patient's surveillance program. In our experience, the risk of stroke was less than 1% per year in all patient groups, if the duplex surveillance is tailored to the individual patient and a policy of repair of high-grade (>75%-80% diameter-reduction) asymptomatic stenosis is adopted. In their paper, Mr Greenhalgh and associates did not define what duplex criteria indicated a high-grade stenosis that warranted consideration for further intervention. At the University of South Florida, according to our patient surveillance data and correlation studies with contrast arteriography, we recommend repair of a progressive atherosclerotic ICA stenosis in appropriately screened surgical candidates when end-diastolic velocity at the site of stenosis is more than 125 cm/s and the ICA:CCA ratio is more than four. For asymptomatic recurrent ICA stenosis, end-diastolic velocity more than 150 cm/s is our threshold for further evaluation by contrast arteriography.

A rational algorithm for duplex scan surveillance after carotid endarterectomy

Purpose: This study was undertaken to determine the appropriate timing and frequency of duplex ultrasound scanning after carotid endarterectomy (CEA) for the detection of high-grade stenosis caused by recurrent carotid stenosis or contralateral atherosclerotic disease progression. Methods: In 221 patients who underwent 242 CEAs, duplex scanning was performed before, during, and after operation (in 3-month to 6-month intervals). High-grade internal carotid artery (ICA) stenosis (peak systolic velocity, >300 cm/s; diastolic velocity, >125 cm/s; ICA/common carotid artery ratio, >4) prompted the recommendation for repair. An average of four postoperative scanning procedures was performed during a mean follow-up period of 27.4 months. Results: Intraoperative duplex scan results prompted the immediate revision of 12 repairs (4.9%), and one perioperative stroke (<1%) occurred. Six CEAs (2.7%) had asymptomatic recurrent stenosis (>50% diameter-reduction [DR]; systolic velocity, >125 cm/s) develop. Only one of six patients had >75% DR stenosis develop and underwent reoperation (<1% yield for CEA surveillance). The yield of surveillance of the unoperated ICA was higher ( P = .003), and 12% of unoperated sides had progressive stenosis (n = 21) or occlusion (n = 3) develop, which led to seven CEAs for high-grade stenosis. Disease progression to >75% DR stenosis was five times as frequent ( P =.002) in patients with >50% DR stenosis initially. All patients but one who required contralateral endarterectomy for disease progression had >50% ICA stenosis when first seen. During the follow-up period, no disabling strokes ipsilateral to an operated carotid artery occurred, but three strokes occurred in the hemisphere of the contralateral unoperated ICA. Conclusion: The yield of duplex scan surveillance after CEA was low. Only 13 patients (5.9%) had severe disease develop to warrant additional intervention. Progression of contralateral disease rather than restenosis was the most common abnormality that was identified. Duplex scanning at 1-year to 2-year intervals after CEA is adequate when a technically precise repair is achieved and minimal contralateral disease (<50% DR) is present. A policy of duplex scan surveillance and reoperation for high-grade stenosis was associated with a 1.6% incidence rate of disabling stroke during the follow-up period. (J Vasc Surg 1999;30:453-60.)

Management of dialysis access–associated steal syndrome: Use of intraoperative duplex ultrasound scanning for optimal flow reduction

Dialysis access–associated steal syndrome (DASS) is an uncommon complication after the creation of an arteriovenous fistula and can cause irreversible ischemic damage in severe cases. Dialysis access–associated steal syndrome has been managed with the surgical reduction of the volume flow in the fistula, but this is associated with a certain incidence of access loss. Several methods are described to achieve the delicate balance between essential flow in the fistula and an adequate limb perfusion pressure. We have developed a new method with duplex ultrasound scanning to quantitate the reduction in volume flow, which will allow effective dialysis and provide adequate limb perfusion. The preoperative assessment was reproduced on the operating table with intraoperative duplex scanning. A 65-year-old woman who underwent this treatment has had resolution of her ischemic symptoms and maintains long-term patency of her dialysis access. (J Vasc Surg 1999;30:193-5.)

The Predictive Value of Intraoperative Duplex for Early Vein Graft Patency in Lower Extremity Revascularization

This study was undertaken to evaluate the ability of intraoperative duplex scanning during infrainguinal vein bypass to identify technical abnormalities and to determine the relation between intraoperative scan result and early primary graft patency. We retrospectively reviewed of 78 consecutive intraoperative duplex scans for infrainguinal vein bypass that were performed between October 1993 and October 1996 during the course of infrainguinal vein bypass. Duplex scans were classified as normal or abnormal based on B-mode image and/or Doppler velocity spectra. Grafts were grouped according to duplex findings and intraoperative action: group I, normal intraoperative scan; group II, abnormal intraoperative scan, revised; group III, abnormal intraoperative scan, not revised. The relationship of intraoperative duplex scan findings to intraoperative graft revision to 1-month and 6-month primary graft patency by life table was analyzed. The analysis demonstrates that the results of intraoperative duplex scans can be used to identify grafts at low risk for early postoperative graft failure (groups I and II), and those at high risk for early postoperative graft failure (group III).

Current Technique for Carotid Endarterectomy

Our current technique for carotid endarterectomy is presented. Modifications have been made over the past 20 years. These include never shunt ing to selective shunting based on stump pressures, primary closure to vein patch closure to prosthetic patch closure, and intraoperative duplex scanning to detect technical defects. Nonetheless, the underlying principle of striving for technical perfection has resulted in excellent results despite variations in the technique.

Adventitial cystic disease of the popliteal artery — A case for intraoperative duplex scanning

Adventitial cystic disease of the popliteal artery — A case for intraoperative duplex scanning