Progression of atherosclerosis in asymptomatic carotid arteries after contralateral endarterectomy: a 10-year prospective study

OBJECTIVE: The best way to manage both symptomatic and asymptomatic severe carotid stenoses has been thoroughly demonstrated by large randomized clinical trials, but less is known about the natural history and management of the contralateral asymptomatic internal carotid artery (ICA). This prospective study was undertaken to determine whether disease progressed in the contralateral ICA of patients who had undergone carotid endarterectomy (CEA) and were followed up clinically and by duplex ultrasound (US) scan. METHODS: The contralateral asymptomatic ICAs of 599 patients who had undergone CEA for severe carotid disease over a 10-year period were followed up clinically and with duplex US scan at 1 month and then every 6 months. ICA stenosis was classified as mild (30%-49%), moderate (50%-69%), severe (70%-99%), or occlusion. Progression was defined as an increase in ICA stenosis of 50% or more for ICAs with a less than 50% baseline lesion or as an increase to a higher category if the baseline stenosis was 50% or more. End points of the study were the incidence of contralateral disease progression and late neurologic events. Kaplan-Meier analysis was used to estimate freedom from disease progression and from neurologic events. The relationship between progression and risk factors was also analyzed. RESULTS: Overall, disease progressed in 25.2% of patients (151/599) after a mean follow-up of 4.1 years. Disease progressed in 34.3% of patients (101/294) with mild stenosis vs 47.9% of patients with moderate stenosis (47/98; P = .016). Three additional patients with mild lesions at baseline progressed to severe lesions. The median time to progression was 29.8 months for mild and 18.5 months for moderate stenoses (P = .033). The rate of late neurologic events referable to the contralateral ICA was 3.2% (19/599) for the entire series and 4.8% (19/392) for patients with a 30% or greater ICA stenosis: these included 4 (0.7%) strokes and 15 (2.5%) transient ischemic attacks. All but 3 events (16.3%; 16/98) occurred in patients with disease progression from moderate to severe stenosis. Overall, 53 late CEAs were performed. CONCLUSIONS: This prospective analysis has shown that disease progression in contralateral asymptomatic ICAs after CEA is relatively common in patients with a diseased ICA at the baseline and strongly supports duplex US surveillance, approximately every 6 months, in patients with more than mild disease. A baseline lesion is significantly predictive of progression to severe stenosis, and progression from moderate to severe stenosis is strongly associated with neurologic clinical events. No demographic or clinical factor proved useful in identifying patients likely to experience disease progression.     

Natural history of atherosclerotic renal artery stenosis associated with aortic disease

The natural history of atherosclerotic renal artery stenosis has not been well defined, particularly when discovered in conjunction with aortic disease requiring correction. To better define the natural history of such lesions, 194 sequential aortograms in 48 patients were studied to define predictive criteria for stenoses at risk for progression. Sixty-six unsuspected atherosclerotic renal arterial stenoses were identified on the initial aortograms. Disease progressed in 42 arteries (53%), 14 bilateral and 28 unilateral. Seven arteries developed occlusion. All had stenoses averaging 80% (range 61% to 94%) noted on the most recent aortogram preceding occlusion. Risk factors including smoking, diabetes mellitus, elevated serum lipids, coronary artery disease, peripheral arterial disease, or change in blood pressure or creatinine, did not correlate with degree or rate of progression of the renal artery stenosis. A difference in kidney size, although varying inversely with degree of stenosis, was not a statistically significant marker of disease progression. This analysis suggests that identification of renal arterial stenoses that will progress is best determined by sequential aortography. Highly stenotic vessels are more prone to occlude than those less stenotic. Consequently, individuals with preocclusive lesions should benefit from prophylactic renal revascularization during aortic reconstruction.     

Natural history of atherosclerotic renal artery stenosis: A prospective study with duplex ultrasonography

Purpose: Although the prevalence of renal artery stenosis in patients with peripheral arterial disease is in the range of 30% to 40%, the role of renal revascularization in patients without severe hypertension or kidney failure is controversial. Duplex scanning is a noninvasive technique that is ideally suited for screening and follow-up of renal artery disease. The purpose of this study was to document the natural history of renal artery stenosis in patients who were not candidates for immediate renal revascularization.Methods: Eighty-four patients with at least one abnormal renal artery detected by duplex scanning were recruited from patients being screened for renal artery stenosis. Of the 168 renal artery/kidney sides, 29 were excluded (15 prior interventions, 6 nondiagnostic duplex scans, 8 presumed nonatherosclerotic lesions), leaving 80 patients with 139 sides for the follow-up protocol. Renal arteries were classified as normal, less than 60% stenosis, 60% or greater stenosis, or occluded by use of previously validated criteria.Results: The study group included 36 men and 44 women with a mean age of 66 years who were monitored for a mean interval of 12.7 months. The initial status of the 139 renal arteries was normal in 36, less than 60% stenosis in 35, 60% or greater stenosis in 63, and occluded in 5. Although none of the initially normal renal arteries showed disease progression, the cumulative incidence of progression from less than 60% to 60% or greater renal artery stenosis was 23% ± 9% at 1 year and 42% ± 14% at 2 years. All four renal arteries that progressed to occlusion had 60% or greater stenoses at the initial visit, and for those sides with a 60% or greater stenosis, the cumulative incidence of progression to occlusion was 5% ± 3% at 1 year and 11% ± 6% at 2 years. The mean decrease in kidney length associated with progression of renal artery stenosis to occlusion was 1.8 cm.Conclusions: Progression of renal artery stenosis, as defined in this study, occurs at a rate of approximately 20% per year. Progression to occlusion is associated with a marked decrease in kidney length. Whether this natural history can be improved by earlier intervention for renal artery stenosis remains to be determined. (J VASC SURG 1994;19:250-8.)     

Incidence, time-of-onset, and anatomical distribution of recurrent stenoses after remote endarterectomy in superficial femoral artery occlusive disease.

PURPOSE: The incidence, time-of-onset, and anatomical distribution of recurrent stenoses after remote endarterectomy in superficial femoral artery (SFA) occlusive disease were studied. METHODS: Patients undergoing SFA remote endarterectomy procedures were examined with duplex surveillance. Patients were examined at 6 weeks, 3, 6, 9, and 12 months, and then annually. Recurrent stenosis was defined as a peak systolic velocity ratio of 2.5 or higher. Duplex results were also compared with clinical and hemodynamic changes. RESULTS: Restenoses were identified in 46 of 101 (46%) limbs treated after a mean interval of 5.8 months (range, 1 to 18 months). These 46 limbs formed the base of this study. The median follow-up period was 25 months. Thirty-eight (83%) of all restenoses were detected within 1 year. The lesions were located within the entire SFA and were not specifically related to the adductor canal or distal stented region only. Multiple stenoses were found in 21 limbs. Only 10 (22%) restenoses were correlated with worsening of clinical symptoms, change of ankle-brachial index, or both. Ten of 23 cases (43%) of nonrevised restenoses progressed to occlusion. These 10 occlusions occurred in all patients with restenosis that developed within the first year. Nonrevised late restenoses (more than 1 year) were not associated with any reocclusion. CONCLUSION: Recurrent stenoses after SFA remote endarterectomy were noticed in 46 of 101 (46%) limbs. Most restenoses (83%) developed within the first year. In the nonrevised group, time-of-onset restenosis (less than 1 year) was correlated with a higher risk for occlusion ( P =.02). The location of restenoses were found without any anatomical site of preference along the entire endarterectomized SFA segment.     

Patency of superficial femoral vein employed as a crossover femoral artery bypass conduit

This study assesses the patency of superficial femoral vein used as a crossover femoral artery bypass conduit in patients presenting either with localized groin sepsis, generalized sepsis or in patients with occluded or heavily diseased superficial femoral artery outflow. Twenty patients were followed prospectively with femoral crossover grafts constructed of superficial femoral vein. Twelve patients presented with sepsis and 8 with chronic ischemia from iliac artery occlusion and severely diseased superficial femoral artery outflow. Graft patency was assessed with regular duplex ultrasound examination. There was one perioperative death. Six patients died during the follow-up period. Mean follow-up time was 24.3 months. No graft occluded or required revision. There was no limb loss, graft infection, or graft hemorrhage. Superficial femoral vein offers an effective femoral crossover bypass graft in patients with either localized/generalized sepsis or disadvantaged outflow tracts.     

Reoperation within 2 years of aortofemoral bypass

The authors analysed 267 consecutive primary aortofemoral grafts to identify the reasons for reoperation within the first 2 years postoperatively. Forty-one (8%) of the 521 limbs required a second operation. Precursors to reoperation were: occlusion of a superficial femoral artery (12%), gangrene (27%) and severe acute ischemia (35%). The rationale for reoperation was classified as technical 11, questionable selection (candidates for percutaneous transluminal angioplasty or inappropriate operation) 9, disease progress 11, residual symptoms 9, contralateral symptoms 1. The commonest technical problem was blind endarterectomy which preceded seven reoperations, five for thrombosis of the graft or a superficial femoral artery which was patent initially. Although 218 limbs had an occluded or severely stenosed superficial femoral artery, only 26 (12%) required reoperation within the first 2 years. The authors believe that the incidence of reoperation after aortofemoral bypass can be reduced by identifying the limbs at risk, by appropriate selection for percutaneous transluminal angioplasty, avoiding blind outflow endarterectomy and considering concomitant femoropopliteal bypass when gangrene is present.     

Noninvasive detection of iliac artery stenosis in the presence of superficial femoral artery obstruction.

In patients with superficial femoral artery obstruction, iliac disease may be difficult to diagnose by commonly used noninvasive techniques. We studied common femoral artery acceleration time (onset of systole to peak systole), as measured from a Doppler spectral display and expressed in milliseconds. Previous work has suggested that an acceleration time of 144 msec or greater is abnormal and is associated with iliac stenosis (greater than or equal to 75% diameter reduction) or occlusion. During a 2-year period, in 139 limbs with superficial femoral artery obstruction, acceleration times were measured immediately before angiography. The overall test accuracy was 94.2% (131/139). In the 112 sides with normal angiograms, the acceleration time correctly identified no disease in 109 patients (97.3% specificity), and in the 27 iliac stenoses or occlusions the test detected disease in 22 patients (81.5% sensitivity). This appears to be a good test that can be done with equipment usually available in most vascular laboratories.     

Current management of the patient with internal carotid artery occlusion

Despite the recent controversy concerning surgical therapy of patients with carotid artery disease, rational therapeutic plans can be developed based on available data. The patient who is symptomatic from occlusion of one or both internal carotid arteries is at particularly high risk for development of stroke and can ill-afford indecision. All symptomatic patients, therefore, with any of the extracranial occlusive disease patterns described are potential surgical candidates. Conversely, among the asymptomatic patients with these same patterns of occlusion, only those with internal carotid occlusion and contralateral stenosis should be considered for surgical therapy. Treatment must be individualised and directed at revascularising stenotic (not occluded) internal carotid arteries, or important collateral vessels such as the external carotid artery and in fewer cases the vertebral artery. The asymptomatic patient with unilateral internal carotid artery occlusion and no contralateral lesions should be monitored closely with Duplex scanning for development of a contralateral stenosis. When a stenosis of 80% or greater is encountered, strong consideration should be given to prophylactic endarterectomy in these patients due to their high risk for stroke. Endarterectomy for a 50-60% stenosis may also be reasonable in a single patent internal carotid artery. In the absence of a significant contralateral stenosis, no treatment is necessary. Individuals with internal carotid artery occlusion and symptoms referable to a contralateral carotid stenosis should also be managed with endarterectomy of the stenotic carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Femoral pulsatility index in the evaluation of aortoiliac occlusive disease

Accurate, noninvasive, hemodynamic assessment of atherosclerosis involving the aortoiliac segment remains a frontier in vascular surgery. Femoral pulsatility index, a vessel/probe angle independent function derived from the common femoral artery sonogram, was evaluated by comparison to the invasive hemodynamic parameters of pressure and flow in the presence of experimentally produced, quantitated, iliac and superficial femoral arterial stenoses. The external iliac, common femoral, and superficial femoral arteries in 10 adult mongrel dogs were used. An arterial constrictor was placed around the external iliac and ipsilateral superficial femoral arteries so that the vessels could be constricted either individually or simultaneously. Superficial femoral artery branch vessels were cannulated for monitoring of intraarterial pressure. Simultaneously, flow was measured from the common femoral artery by a square-wave electromagnetic flow meter together with directional Doppler ultrasound magnetic tape recordings. Sound signals were then processed through a frequency spectrograph for calculation of pulsatility index. With increasing degree of stenosis, decreases in pulsatility index paralleled decreases in both pressure and flow. Large individual variance in femoral pulsatility index existed among animals for any given degree of stenosis. Changes in pulsatility index recorded from the common femoral artery were not significantly different when either an iliac artery stenosis or superficial femoral artery stenosis was present. In this nonatherosclerotic canine model using accurately placed and quantitated arterial stenoses, femoral pulsatility index was unable to reliably quantitate arterial stenoses and could not differentiate between inflow and outflow lesions.     

Alterations in femoral artery hemodynamics associated with femoropopliteal bypass

Subcritical iliac artery stenoses become critical stenoses if common femoral artery (CFA) flow rates increase sufficiently. Infrainguinal bypasses done in the presence of subcritical iliac artery stenoses may be in jeopardy on the basis of inadequate inflow if critical iliac stenoses are produced by increased CFA flow resulting from the bypasses. This study was undertaken to define the CFA hemodynamic changes seen with femoropopliteal bypass and to determine the relative effects of subcritical iliac artery stenoses on these pressure and flow changes. The iliac and femoral arteries of five canine hindlimbs were isolated for placement of a constricting microcaliper, intraarterial pressure cannula, and electromagnetic flow probe. Systemic pressure was monitored via the contralateral CFA. CFA pressure and flow were measured at incremental iliac artery stenoses with the superficial femoral artery (SFA) occluded and with the SFA patent, simulating femoropopliteal bypass. Indices of CFA pressure/systemic pressure (FAI) and percentage increases in CFA flow with open versus occluded SFAs were calculated. CFA flow rates were significantly higher with open versus occluded SFAs, with and without iliac artery stenoses present. Despite these increases in CFA flow, CFA pressure indices were unchanged when comparing open with occluded SFAs even in the presence of subcritical iliac artery stenoses. These findings suggest that femoropopliteal bypass does not result in increases in CFA flow rates sufficient enough to cause decreased graft perfusion pressures in the presence of subcritical iliac artery stenoses. Therefore, the patency of an infrainguinal bypass done in the presence of a subcritical iliac artery stenosis should not be adversely affected in the early postoperative period on the basis of inflow.     

Combined percutaneous transluminal angioplasty and extraanatomic bypass for symptomatic unilateral iliac artery occlusion with contralateral iliac artery stenosis

We have reviewed our experience with percutaneous transluminal angioplasty of contralateral iliac stenosis and extraanatomic bypass of the occluded iliac artery. Twenty-two men and nine women with a mean age of 65 years (range 46 to 84) presented with symptomatic iliac occlusive disease. Twenty-four (77%) had disabling claudication, four (13%) rest pain, and three (10%) ischemic tissue loss. Six (19%) had undergone previous vascular reconstructive procedures. All had an occluded iliac artery on the symptomatic side and greater than 50% stenosis of the contralateral iliac artery. Percutaneous transluminal angioplasty of the iliac stenosis was done prior to extraanatomic bypass, using polytetrafluoroethylene. There were six late deaths after discharge. The only significant complication was a femoral artery thrombosis which was corrected when the bypass graft was performed. Cumulative primary graft patency was 89% at one year and 81% at three years. The crossover graft occluded in six patients, five within 48 months of surgery, and one after nine years. One of these occluded grafts was salvaged by thrombectomy, for a secondary patency rate of 85% at three years. Two patients required aortobifemoral bypass, one an iliobifemoral bypass and one an ilioprofunda bypass. One patient operated upon for rest pain came to below-knee amputation. Mean resting ankle/brachial systolic pressure index increased significantly on the side of the iliac occlusion from 0.35 ±0.21 to 0.70 ± 0.20 (p < 0.05, paired t test) after the combined procedure. There was no significant difference in the mean resting ankle/brachial systolic pressure index on the contralateral side (0.60 ± 0.22 to 0.65 ± 0.27, ns). Combined iliac percutaneous transluminal angioplasty and femorofemoral bypass is a safe alternative to aortobifemoral bypass for selected patients with aortoiliac arterial occlusive disease. Presented at the Royal Australasian College of Surgeons, General Scientific Meeting, May 1989, Melbourne, Australia.     

Serial hemodynamic assessment of aortobifemoral bypass

Clinical, arteriographic, and vascular diagnostic laboratory (VDL) data on 157 patients undergoing aortobifemoral bypass (ABF/BP) more than 5 years previously were compared in terms of the perspective provided by noninvasive testing, particularly when performed in the face of superficial femoral artery (SFA) occlusion. To the traditional outcome criteria (operative mortality rate, 3.2%; amputation rate, 1.4%; early patency rate, 98%; and late patency rate, 86%), VDL data added an initial hemodynamic failure rate of 14% and a late deterioration rate of 8%. Those patients with occluded SFAs fared worse in regard to initial patency (94% vs. 100%), initial hemodynamic failure (29% vs. 2%), late deterioration (8.8% vs. 5.4%), and late failure rates (16% vs. 10%), whereas those patients with open SFAs suffered more distal disease progression (11.5% vs. 1.3%). "Prediction" of postoperative ankle/brachial index (ABI) from preoperative thigh/brachial index (TBI) and ABI was 92% accurate for limbs with open SFAs but only 84% for limbs with occluded SFAs; prediction was made with a formula based on proportional transmission and with TBI measured with a regularly sized cuff (best combination). Neither additive transmission formula nor measurement of TBI with a large cuff allowed accurate prediction when the SFA was occluded. No advantage, in terms of initial hemodynamic result or late outcome, could be demonstrated for limited profundaplasty in the absence of significant profunda femoral stenosis and end-to-end vs. end-to-side proximal anastomosis.     

Stenosis of one carotid artery with occlusion of the contralateral carotid

Summary 23 patients with unilateral internal carotid artery stenosis (>70%) and contralateral internal carotid artery occlusion in the neck are reported. The symptoms are referable to the side of the occlusion in 13 cases (57%), to the side of stenosis in 7 cases (30%) and non-localizing in 3 cases (13%). All 23 patients had a carotid endarterectomy performed on the side of the stenotic lesion. There was no operative mortality. Late neurological symptomatology after surgery was referable to the side of stenosis in 13% and to the side of occlusion in 9%. The authors consider that, in cases of significant stenosis (greater than 70%) of an internal carotid artery with a contralateral occlusion, preference should always be given to endarterectomy of the stenotic side, reserving extra-intracranial by-pass of the occluded side for patients who remain symptomatic after endarterectomy of the stenotic side.     

A twelve-year experience with the popliteal-to-distal artery bypass: the significance and management of proximal disease.

The value of the popliteal-to-distal artery bypass in limb salvage is well documented. However, the influence of progression of disease in the superficial femoral artery or proximal popliteal artery, and the role of percutaneous transluminal angioplasty of these vessels before bypass have not been adequately assessed. To evaluate these and other factors, we reviewed our experience with 153 nonsequential popliteal-to-distal artery bypasses performed over a 12-year period. Limb salvage was the indication for all procedures, and 87% of the patients were diabetic. The 5-year primary and secondary graft patency rates were 55% and 60%, respectively, and the limb salvage rate was 73%. Preoperative arteriograms were evaluated for stenosis in the superficial femoral artery or popliteal artery proximal to the graft. Fifty-six grafts with a proximal stenosis 20% or less were identified and had primary graft patency of 77% at 2 years, similar to the 70% patency for the 20 grafts placed distal to a 21% to 35% stenosis. The 18 grafts placed distal to a stenosis greater than 35% had 53% 2-year primary graft patency (p = 0.25). Percutaneous transluminal angioplasty of a superficial femoral artery or popliteal artery stenosis (24% to 85% luminal narrowing) in 19 limbs resulted in 68% 2-year graft patency, not significantly lower than grafts with 35% or less proximal stenosis (75%, p = 0.25). Other factors associated with significant decreases in graft patency included a vein graft diameter less than 3.0 mm, a dorsalis pedis outflow site, and poor quality outflow. Thus the popliteal-to-distal bypass is a durable procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

股浅动脉长段闭塞的治疗

目的 分析研究常规球囊扩张与切割球囊相结合在股浅动脉长段闭塞治疗中的扩张效果和中期疗效.方法 2009年6月～2010年7月间应用常规球囊扩张联合切割球囊治疗51例动脉硬化闭塞症股浅动脉长段闭塞患者,观察其临床疗效.结果 51例患者中有49例导丝通过闭塞段,动脉直径狭窄率为35％～83％.治疗后患者重度狭窄部位的狭窄程度平均减少至37％,其他部位的狭窄程度减少至20％左右,未发生动脉壁撕裂,穿孔出血合并症.术后1年CTA复查有13％的患者再次出现闭塞,未闭塞的患者中动脉最狭窄处狭窄程度平均为55％.结论 常规长球囊与切割球囊相配合可以有效地治疗股浅动脉长段闭塞,中期效果较好,但长期疗效有待于进一步观察.     

Disease progression in contralateral carotid artery is common after endarterectomy

OBJECTIVE: Although the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Atherosclerosis Study (ACAS) have helped to define the role of carotid endarterectomy (CEA) for both symptomatic and asymptomatic lesions, the role of surveillance of the contralateral carotid artery remains unclear. The purpose of this study was to determine the progression of contralateral carotid artery disease with serial duplex ultrasound scans after CEA compared with the recurrent stenosis rate for the carotid artery ipsilateral to the CEA. METHODS: From January 1990 to December 2000, 473 CEA procedures were performed at a Veterans Affairs Medical Center. From this group we identified 279 patients who had undergone first-time CEA, as well as preoperative duplex scanning and postoperative duplex scanning at least once, in the vascular laboratory. At each visit stenosis of the internal carotid artery (ICA) was categorized as none (0%-14%), mild (15%-49%), moderate (50%-79%), severe (80%-99%), or occluded. Analysis of probability of freedom from progression was determined. Progression was defined as an increase in ICA stenosis 50% or greater or increase to a higher category of stenosis if baseline was 50% or greater. The Cox proportional hazards model was used for data analysis. RESULTS: Mean patient age was 65.7 years (range, 33-100 years). The 1024 carotid duplex ultrasound scanning examinations performed (mean, 3.7; range, 2-13) included the last study done before the index CEA and all studies done after the CEA. Mean follow-up was 27 months (range, 1-137 months). Forty-six patients were found to have contralateral carotid occlusion at initial duplex scanning, and were therefore excluded from the contralateral progression analysis. Contralateral progression was more frequent than ipsilateral recurrent stenosis at long-term follow-up (P <.01). Annual rates of "any progression" and "progression to severe stenosis or occlusion" were 8.3% and 4.4%, respectively, for contralateral arteries, and 4.3% and 2.4%, respectively for ipsilateral arteries. As a result of surveillance, 43 contralateral CEAs (19% of initial cohort) were performed. Carotid stenosis regressed in 25 arteries (10.7%). Baseline clinical and demographic factors did not predict disease progression. Baseline contralateral stenosis did not predict time to "any progression," but was a strong predictor of "progression to severe stenosis or occlusion" (P <.001). CONCLUSIONS: After CEA, we identified an 8.3% annual rate of progression of contralateral carotid artery stenosis and a 4.4% annual rate of progression to severe stenosis or occlusion. Baseline contralateral stenosis was significantly predictive of progression to severe stenosis or occlusion. Clinical and demographic factors were not helpful in predicting which patients would have disease progression. These data may help in assessing the cost effectiveness of duplex scanning surveillance after CEA.     

Risks of stroke and current indications for cerebral revascularization in patients with carotid occlusion

Preventing further stroke in patients with complete carotid artery occlusion remains a difficult challenge because there is no therapy proven effective for this prevention. These patients comprise approximately 15% of patients with carotid artery territory transient ischemic attacks or infarction. Patients with symptomatic carotid artery occlusion have an overall risk of subsequent stroke of 7% per year and a risk of stroke ipsilateral to the occluded carotid artery of 5.9% per year. The presence of severe hemodynamic failure demonstrated by increased oxygen extraction fraction (OEF) of the brain, in a cerebral hemisphere distal to a symptomatic occluded carotid artery, is an independent predictor of subsequent ischemic stroke with a risk comparable to that seen in medically treated patients with symptomatic severe carotid artery stenosis.     

Some determinants of papaverine-induced femoral artery pressure gradients

The accuracy and reliability of papaverine-induced central arterial to common femoral artery pressure gradients, frequently used to estimate the hemodynamic significance of aortoiliac stenosis, depend on a reproducible, between patient increase in resting common femoral artery blood flow because of the linear relationship between pressure gradient and flow. Blood flow variability and the effect of proximal and distal occlusive disease on femoral artery pressure gradient and flow were determined by three methods: intraoperative electromagnetic blood flow measurements, hemodynamic model analysis, and flow calculations using intraoperative segmental resistance measurements. The ratios of papaverine-induced hyperemic to resting common femoral artery blood flow were 2.80 +/- 0.781 (mean +/- 1 SD, n = 19) for occluded and 3.07 +/- 0.819 (n = 13, P greater than 0.5) for open superficial femoral arteries, respectively, when the papaverine-induced central arterial to common femoral artery mean pressure gradient was less than 10 mm Hg. The flow ratios were 2.70 +/- 1.093 (n = 16) and 2.93 +/- 1.027 (n = 10, P greater than 0.5) for superficial femoral occlusion and patency, respectively, when the central to femoral mean pressure gradient was greater than or equal to 10 mm Hg. Hemodynamic model analysis predicts that superficial femoral artery occlusion reduces the hyperemic to resting common femoral artery flow ratio from 2 to 1.8 and from 3 to 2.5. The mean values of segmental resistance measured intraoperatively in 17 additional limbs with and in 17 without superficial femoral occlusion predict a reduction in flow ratios from 2 to 1.75 and from 3 to 2.44 when the superficial femoral is occluded.(ABSTRACT TRUNCATED AT 250 WORDS)     

THE VALUE OF DUPLEX SCANNING IN SURVEILLANCE OF INFRA-INGUINAL VEIN AND SYNTHETIC GRAFTS

The contribution of duplex scanning to improving early diagnosis of graft stenosis was evaluated in 195 patients after infra-inguinal bypass procedures. Over a 31 month period, 406 duplex scans were obtained on 232 limbs with 191 vein and 41 polytetrafluoroethylene (PTFE) grafts. Peak systolic velocities > 200cm/s with spectral broadening and lumen reduction on B-mode image were the criteria adopted for identification of a haemodynamically significant (> 50%) stenosis. Sixty-one stenoses were identified in 55 of the grafted limbs. Thirty-three of the 55 limbs had a subsequent angiogram. The angiogram showed graft occlusion in six limbs, graft stenosis in 18, and native artery stenosis in four. Twenty-one of the grafts had the angiogram within 1 month after the duplex had detected graft stenosis, and one (4.76%) became occluded in this interval. Seven had an angiogram more than 1 month after the duplex study, and five (71.4%) had become occluded. The angiographic study did not confirm a graft stenosis in five limbs. Three were submitted to operation and stenosis was confirmed. Seventeen graft thromboses were detected by duplex scanning. Graft thrombosis was demonstrated following a previous negative duplex scan in one of the 106 vein grafts (0.94%), and in four of 30 PTFE grafts (13.3%). Duplex scanning is effective in the detection of graft stenosis. The precise anatomical location is less accurate when in the region of an anastomosis. Early attention should be taken when duplex studies suggest critical graft stenosis because there is a high risk of occlusion. Polytetrafluoroethylene grafts tend to thrombose without a precursory focal stenosis.     

Incidentally detected stenoses proximal to grafts originating below the common femoral artery: do they affect graft patency or warrant repair in asymptomatic patients?

OBJECTIVE: Stenoses in infrageniculate arteries proximal to a lower extremity vein graft may reduce flow velocity through the bypass graft and are thought to predispose to graft occlusion. Repair of these lesions has been recommended to preserve graft function. This study was undertaken to better define the natural history of grafts below inflow lesions and to evaluate the necessity of repair to preserve graft patency. METHODS: From 1994 through 1999, patients undergoing lower extremity vein grafts by a single surgeon at a university hospital and an affiliated teaching hospital were placed in a prospective protocol for proximal infrageniculate native artery and graft surveillance through use of duplex scanning. The records of those patients with grafts originating distal to the common femoral artery were evaluated; they form the basis for this report. Arteriograms were obtained before bypass grafting, and no patient had a stenosis greater than 50% diameter reduction proximal to the graft origin. Follow-up scans were obtained from the common femoral artery through the graft and outflow artery. The peak systolic velocity and velocity ratio in an infrageniculate native artery proximal to the graft origin were recorded, as were the location and the time interval since the bypass graft. Repair of these proximal lesions was not performed during the course of this study. Revision of the bypass graft or its anastomoses was undertaken according to preestablished duplex scan criteria. RESULTS: During this time, 288 autogenous infrainguinal bypass grafts were performed, of which 159 originated below the common femoral artery; of these, 74 were from the superficial femoral artery, 29 from the profunda femoris artery, 49 from the popliteal artery, and 7 from a tibial artery. The maximum peak systolic velocity proximal to the graft origin was more than 250 in 38 arteries (25%) and more than 300 in 26 arteries (16%). The velocity ratio was 3.0 or more in 32 arteries at the same location as the peak systolic velocity and 3.5 or more in 23 arteries (15%), confirming hemodynamically significant stenoses at these sites. The location of peak systolic velocity was the common femoral artery in 81 patients (51%), the superficial femoral artery in 50 (31%), the popliteal artery in 22 (14%), and a tibial artery in 6 (4%). Follow-up ranged from 8 to 60 months (mean, 35 months). During follow-up, 19 patients died, 18 with patent grafts. Overall, nine grafts occluded. One of the occluded grafts had a velocity ratio greater than 3.0; this may have contributed to graft thrombosis. The other occlusions resulted from an unrepaired graft lesion in 2 patients, graft infection in 2 patients, and graft ligation necessitated by below-knee amputation in 2 patients. No cause for the occlusion could be identified in two of the grafts (neither had evidence of proximal arterial stenosis). Assisted primary patency rates were 95% and 91% at 3 and 5 years, respectively. CONCLUSIONS: For grafts originating distal to the common femoral artery, stenoses proximal to the graft do not affect bypass graft patency and do not require repair to prevent graft occlusion. Surveillance of these lesions may therefore be unnecessary, inasmuch as the repair of proximal lesions should not be undertaken to preserve graft function.