Claviculectomy for subclavian venous repair: long-term functional results.

OBJECTIVES: The purpose of this study was to determine the long-term functional results after medial claviculectomy and venous patch angioplasty or bypass grafting using internal jugular vein after incomplete thrombolysis of effort thrombosis of the subclavian vein. METHODS: The records of 11 patients with effort thrombosis who were treated over the past 9 years were reviewed. Patients have been followed up between 3 and 9 years at 6-month intervals with duplex imaging and contrast venography when indicated and have had an orthopedic evaluation of their shoulder function. RESULTS: All reconstructed veins are patent, and only one patient complains of any arm swelling after prolonged usage. This patient is one of three with postphlebitic changes at the site of repair and has similar findings in her basilic vein. All patients have returned to their prethrombosis vocation without limitation. Four of the 11 patients have jobs requiring heavy physical labor. No patient describes any limitations of shoulder function, but one man who works as a diesel mechanic complains of shoulder aching with overuse with repetitive pulling. Three patients describe upper extremity paresthesias when lying on the operated side. Two patients (one man and one woman) are bothered by the large scar and indentation at the site of the incision. Every patient considers the overall result completely successful from a functional standpoint. CONCLUSIONS: Early subclavian venous repair performed through a medial claviculectomy is a durable operation with excellent long-term functional results. Half of the patients noted minor but significant symptoms, but all are uniformly able to return to normal function.

A condemnation of subcutaneous fasciotomy.

Controversy exists regarding the indications and methods for lower-extremity fasciotomy. Two recent cases at our institution in which recurrent, acute limb-threatening ischemia occurred despite adequate fascial division have convinced us that in certain situations subcutaneous fasciotomy is clearly inadequate. In both patients, both of whom were young, intact healthy skin between the lower extent of the incision and the malleolus acted as a tourniquet, causing recurrent compartment syndrome as reperfusion edema occurred after initial repair. We believe that therapeutic fasciotomy in young patients with relatively noncompliant skin should include division of skin from the knee to the ankle on at least one side to prevent a tourniquet effect by intact skin at the ankle.

Value of preoperative EEG for carotid endarterectomy.

PURPOSE: This study was designed to determine whether the preoperative, baseline electroencephalogram (EEG) can be used for intraoperative decision making during carotid endarterectomy, and to identify circumstances where the EEG can be eliminated. METHODS: The charts of all patients undergoing carotid endartectomy at the authors' institution from June 1991 to May 1995 were reviewed to identify those patients that had adequate pre- and intraoperative EEG monitoring. EEGs during 331 carotid endartectomies in 303 patients were coded without knowledge of outcome; primary and secondary endpoints were EEG changes with clamping and clinical outcome, respectively. RESULTS: The incidence of mortality and major neurological morbidity was 1.8%. Baseline-EEGs were abnormal in 105 patients (32%). Whereas baseline-EEG changes were highly predictive of EEG changes after anesthetic induction (P < .0001), they were not predictive of EEG changes with clamping or of clinical outcome. Prior stroke (CVA) predicted abnormal baseline-EEGs (P < .0001) and abnormal post-anesthetic EEGs (P < .0001) but did not predict changes with clamping or perioperative CVA. EEG changes with clamping occurred during 18% of operations; such changes were predicted only by contralateral occlusion (P < .0016) and EEG changes during a prior contralateral carotid endartectomy (P < .0001). The only variable that predicted an adverse neurological outcome was the presence of contralateral occlusion, which increased the likelihood of a perioperative neurological event seven-fold (P = .0038). Clinical outcomes in the 57 of 105 patients with abnormal baseline-EEGs and the 49 of 83 with prior CVA who were shunted were not different from those who were not. CONCLUSIONS: baseline-EEG is not of value for the prediction of adverse events during carotid endartectomy and can be eliminated. Because contralateral occlusion is highly predictive of changes with clamping, and patients undergoing a second carotid endartectomy will usually manifest EEG changes identical to those at the first, operative EEG monitoring can also be eliminated from both these circumstances. Finally, prior stroke does not lead to a higher incidence of clamp-induced EEG changes, and thus is not an indication for shunting in and of itself.

Ruptured popliteal artery aneurysm.

Popliteal artery aneurysms rarely rupture. We treated a 91-year-old man who presented with a deep venous thrombosis and anemia; rupture of a popliteal artery aneurysm was suspected only after compartment syndrome isolated to the thigh developed as the result of bleeding. Although fasciotomy was required on the basis of the clinical examination alone, the cause of the problem, operative strategy, and definitive treatment (i.e., resection and bypass) were clarified by the preoperative computed tomography scan. Ruptured popliteal aneurysm can manifest as a massively swollen leg with anemia and should be suspected if no other cause is evident.

Carotid endarterectomy.

Although controversies still exist, recently reported trials have confirmed the efficacy of carotid endarterectomy and more clearly elucidated the appropriate indications for surgical therapy. The efforts to optimize outcomes for patients with carotid artery disease have expanded to the asymptomatic patient, the patient suffering from stroke, and the patient with coexistent cardiac symptoms.

Fate of the proximal aortic cuff: implications for endovascular aneurysm repair.

PURPOSE: Long-term success of endoluminally placed grafts for exclusion of abdominal aortic aneurysms (AAAs) relies on secure fixation at the proximal and distal cuffs and, as such, assumes that the fixation sites will not dilate over time. Data regarding this issue, however, are not yet available. This study was performed to evaluate the region of the proximal anastomosis in patients many years after having undergone conventional AAA repair to determine the potential for late dilatation after placement of an endoluminal device. METHODS: Three hundred forty-six patients underwent repair of an infrarenal AAA at our institution between January 1985 and December 1990. Of 97 eligible living patients, 33 both had their original CT scans available and underwent repeat scanning at a mean of 88.6 +/- 23.8 months (mean +/- SD; range, 40 to 134 months) after repair. RESULTS: The overall 5-year survival rate was 73%. The mean preoperative infrarenal aortic cuff diameter by CT scan was 24.5 +/- 3.7 mm (range, 19 to 33 mm). At an average of 89 months after repair, the mean infrarenal aortic diameter increased 4.3 mm to 28.8 +/- 7.7 mm (range, 20 to 52 mm; p = 0.0004 by t test). The proximal cuff at this time measured 30 mm or more in 11 patients (33%), and as early as 6 years after operation three of the seven patients (43%) scanned within this time period had cuffs that were dilated to 30 mm or more. Late dilatation to 30 mm or more was rare (16%) in patients who had preoperative cuffs that measured 27 mm or less. The mean late iliac artery size was 16.9 +/- 8.9 mm (range, 10 to 52 mm), and 30% (10 of 33) measured 20 mm or more. CONCLUSIONS: One third of all patients who survive AAA repair experience significant dilatation of their proximal aortic cuff over time. Proximal dilatation is rare but not absent in patients who have smaller initial aortic cuff diameters. This dilatation rarely causes problems after conventional suture fixation, but the long-term implications of cuff dilatation after endoluminal repair are unclear. Our findings suggest that endovascular aortic prostheses that have the ability to continue to self-expand many years after implantation may be required and that endovascular prostheses may not be the best option for patients who have a long life expectancy or for those who have preoperative proximal cuffs greater than 27 mm.

Primary fibrinolysis during supraceliac aortic clamping.

PURPOSE: An increased incidence of bleeding complications has been observed after supraceliac aortic clamping (SCC). This study was performed to identify possible hemostatic abnormalities that contribute to this problem. METHODS: A prospective cohort study over a 3-month period was performed by comparing hemostatic parameters in 10 consecutive patients who required elective SCC with those of eight concurrent randomly selected control subjects who required infrarenal clamping (IRC) for abdominal aortic reconstruction. Measures of coagulation, fibrinolysis, platelet function, temperature, hemodilution, and hepatic function were performed at selected times before, during, and after operation. RESULTS: Aneurysm size, fibrinogen, D-dimers, prothrombin, partial thromboplastin time, platelet counts, bleeding times, hemodilution, and temperature were comparable in both groups. Patients in the SCC group, however, consistently developed a primary fibrinolytic state within 20 minutes after supraceliac clamping, reflected by significantly decreased euglobulin clot lysis times (ECLT; p < 0.0001), elevated tissue plasminogen activator (t-PA) levels (p < 0.0006), elevated t-PA-to-plasminogen activator inhibitor-1 ratios (p < 0.0001), and reduced alpha 2-antiplasmin levels (p < 0.002). SCC produced hepatocellular injury documented by elevations in both aspartate transaminase (p < 0.0001) and lactate dehydrogenase (p < 0.009). CONCLUSIONS: SCC rapidly induces a primary fibrinolytic state manifested by increased circulating t-PA, reduced alpha 2-antiplasmin, and increased fibrinolytic activator-to-inhibitor ratios. These effects may be a result of hepatic hypoperfusion caused by SCC leading to insufficient clearance of t-PA. Antifibrinolytic agents may be of benefit if bleeding develops after aortic procedures that require supraceliac clamping.

Impact of inflow reconstruction on infrainguinal bypass.

PURPOSE: This study assessed whether multisegmental disease that is severe enough to require an inflow procedure adversely affects infrainguinal bypass patency, limb salvage, or patient survival rates. METHODS: The records of 495 patients who underwent 551 infrainguinal bypass grafting procedures were reviewed. Saphenous vein and prosthetic grafts were evaluated separately. Graft patency rates, patient limb salvage rates, and patient survival rates in those grafts that arose from a reconstructed inflow source were compared with those that arose from normal, nonreconstructed inflow sources. When grafts had either hemodynamic failure or occlusion, the cause of failure was identified. RESULTS: Four-year primary patency rates in vein grafts that arose from a reconstructed inflow sources were lower than those in grafts that arose from nonreconstructed inflow sources (41% vs 54%; p = 0.006). Assisted primary patency rates and secondary patency rates, however, were similar (62% vs 74% and 64% vs 77%, respectively). The 4-year primary patency rate (45% vs 55%), assisted primary patency rate (60% vs 60%), and secondary patency rate (60% vs 61%) in prosthetic grafts did not vary based on inflow source. The most common cause of graft failure was inflow failure, except in the vein grafts that did not require an inflow procedure, in which the most common cause of failure was graft failure. Inflow failure occurred in 24% and 22% of the vein and prosthetic grafts with multisegmental disease, respectively, but in only 7% (p < 0.001) and 10% (p < 0.05), respectively, of those that arose from normal nonreconstructed inflow. The presence of an inflow procedure did not affect limb salvage rates or patient survival rates, regardless of graft material. CONCLUSIONS: Long-term patency rates, patient limb salvage rates, and survival rates in patients with a reconstructed inflow source were similar to those of patients with a normal nonreconstructed inflow. A major cause of occlusion is inflow failure, and this occurs in a greater proportion of patients with multisegmental disease. These patients, in particular, may benefit from patient surveillance to screen for progression of their inflow disease and to allow for intervention before infrainguinal graft occlusion.

Is routine carotid ultrasound surveillance after carotid endarterectomy worthwhile?

BACKGROUND: Periodic ultrasound studies are routinely performed after carotid endarterectomy with the aim of detecting recurrent stenosis or progression of contralateral disease. The frequency with which these studies should be performed and their clinical utility is at present unclear. Our experience with ultrasound surveillance after carotid endarterectomy was reviewed. METHODS: We performed a retrospective analysis of our carotid registry as a follow-up on patients who had undergone primary endarterectomy between 1982 and 1995. The database was searched for events referable to the contralateral carotid artery including incidence of contralateral endarterectomy, progression of contralateral stenosis, and development of new neurologic symptoms. Data was analyzed by life-table methodology. RESULTS: A total of 562 patients underwent 660 endarterectomies during the study interval with a postoperative stroke rate of 3.6% and a mortality of 1.1%. Of these, 496 patients had data available on the contralateral artery. There were 384 patent, nonoperated contralateral arteries available for long-term clinical follow-up, of which 276 had serial Doppler examinations. At the time of initial presentation, 30% of patients (141 cases) had greater than 50% diameter stenosis in the contralateral artery including 45 occlusions. There were 67 contralateral endarterectomies performed within 6 months of the original surgery. An additional 15 endarterectomies were performed within 24 months of the original surgery and only 16 subsequent endarterectomies were performed up to the 8-year follow-up. Progression of contralateral stenosis from less than to greater than 50% occurred in 10.1% of the patient population. The rate of disease progression was 5.1% at 3 years, 17.8% at 5 years, and 30% at 7 years. Stroke-free survival in patients without progression was 94.7% at 3 years and 93.3% at 5 years. CONCLUSIONS: Significant contralateral disease occurs in about one third of patients, most of whom are candidates for early contralateral endarterectomy. In patients who present with minimal contralateral disease, the incidence of progression is low over time. Follow-up duplex examinations on a biennial schedule is sufficient to detect clinically significant disease progression in these patients.

Lesion width as a discriminator of plaque characteristics.

This study evaluated the relative ability of two techniques to quantify carotid atheroma. Diameter stenosis and lesion width were used to predict clinical significance and morphologic characteristics of 54 carotid endarterectomy specimens. Diameter stenosis was a better predictor of symptoms than lesion width (P=0.03 versus P=0.085). Both parameters were predictive of complex atheroma (diameter stenosis P=0.000; lesion width P=0.03). However, use of lesion width allowed finer definition of categories permitting more precise subclassification of plaque. This resulted in a better correlation of symptoms to complexity when lesion width was used as the discriminating variable (lesion width P=0.04; diameter stenosis P=0.121). Lesion width is a valuable parameter for the classification of carotid atheroma, correlating with symptoms and plaque complexity. Lesion width should be evaluated in future studies of carotid atheroma. The discriminative ability of lesion width as detected by high-resolution ultrasonography needs to be evaluated.

Measurement of carotid bifurcation pressure gradients using the Bernoulli principle.

Current randomized prospective studies suggest that the degree of carotid stenosis is a critical element in deciding whether surgical or medical treatment is appropriate. Of potential interest is the actual pressure drop caused by the blockage, but no direct non-invasive means of quantifying the hemodynamic consequences of carotid artery stenoses currently exists. The present prospective study examined whether preoperative pulsed-Doppler duplex ultrasonographic velocity (v) measurements could be used to predict pressure gradients (delta P) caused by carotid artery stenoses, and whether such measurements could be used to predict angiographic percent diameter reduction. Preoperative Doppler velocity and intraoperative direct pressure measurements were obtained, and per cent diameter angiographic stenosis measured in 76 consecutive patients who underwent 77 elective carotid endarterectomies. Using the Bernoulli principle (delta P = 4v(2), pressure gradients across the stenoses were calculated. The predicted delta P, as well as absolute velocities and internal carotid artery/common carotid velocity ratios were compared with the actual delta P measured intraoperatively and with preoperative angiography and oculopneumoplethysmography (OPG) results. An end-diastolic velocity of > or = 1 m/s and an end-diastolic internal carotid artery/common carotid artery velocity ratio of > or = 10 predicted a 50% diameter angiographic stenosis with 100% specificity. Although statistical significance was reached, preoperative pressure gradients derived from the Bernoulli equation could not predict actual individual intraoperative pressure gradients with enough accuracy to allow decision making on an individual basis. Velocity measurements were as specific and more sensitive than OPG results. Delta P as predicted by the Bernoulli equation is not sufficiently accurate at the carotid bifurcation to be useful for clinical decision making on an individual basis. However, end-diastolic velocities alone as well as internal carotid artery/ common carotid artery velocity ratios are highly specific in the prediction of clinically significant carotid stenoses. An end-diastolic velocity of > or = 1 m/s accurately identifies a 50% or greater diameter stenosis, and thus may in some cases be sufficient for operation.

Activated protein C resistance: prevalence and implications in peripheral vascular disease.

PURPOSE: Activated protein C (APC) is a naturally occurring anticoagulant that interacts with factors V and VIII to inhibit the clotting cascade. Resistance to APC (APC-R), hypothesized to occur as a result of an abnormal factor V, has been documented in up to 40% of patients with venous thrombotic events, but its prevalence in patients with arterial disease remains ill defined. METHODS: With an assay of APC resistance that expresses the ratio of the activated partial thromboplastin time with and without the addition of exogenous APC, APC resistance ratios were quantitated in 200 individuals comprising 177 patients with vascular disease and 23 control subjects. An abnormal activated partial thromboplastin time was present in four patients who were excluded from analysis. The 173 remaining patients formed the study population and were divided into diagnostic subgroups on the basis of the most symptomatic problem. RESULTS: APC resistance was documented in 20 individuals, representing 11.6% of the study group. The highest prevalence of APC resistance was observed in patients with lower extremity occlusive disease, with the APC-R ratio below 2.0 in 13.7%. Within the subgroup of individuals with lower extremity disease, 76 patients (10 with APC-R, 13.2%) underwent infrainguinal bypass and were monitored a mean of 47 +/- 8 months. Occlusion of the arterial reconstruction occurred in 22 patients (29%). Six (60%) of the patients with APC-R had failed reconstructions, versus 16 (24%) of 66 patients without APC-R (p = 0.02). CONCLUSIONS: These findings suggest that APC-R is relatively common in patients with peripheral vascular disease, especially in those with lower extremity occlusive disease. APC-R appears to be a risk factor for failure of infrainguinal bypass. These observations suggest that screening for APC-R may be useful in patients with peripheral vascular disease, providing the opportunity to restore the normal thrombogenic balance with anticoagulant therapy in susceptible individuals.

Outpatient echocardiography as a predictor of perioperative cardiac morbidity after peripheral vascular surgical procedures.

PURPOSE: A variety of preoperative provocative tests have been used to define the risk of cardiac morbidity and mortality after peripheral vascular procedures, including dipyridamole myocardial scintigraphy and dobutamine stress echocardiography. Although highly sensitive, these tests are time-consuming and associated with significant expense. We investigated outpatient echocardiography as a less resource-intensive means of assessing cardiac risk with operation. METHODS: Over a 2-year period 250 consecutive patients underwent outpatient transthoracic echocardiography before elective peripheral vascular operation was performed. The accuracy of the Goldman, Detsky, and the American Society of Anesthesiologists' Physical Status Classification clinical indexes of cardiac risk were assessed with regard to the development of cardiac complications such as unstable angina, myocardial infarction, life-threatening ventricular arrhythmias, severe congestive heart failure, and cardiogenic shock. The accuracy of echocardiographically determined left ventricular ejection fraction was determined at threshold values between 20% and 60%. RESULTS: Perioperative cardiac events developed in 23 (9.2%) of the patients, and nine (3.6%) of the patients died as a result of these complications. Clinical indexes lacked sensitivity in the preoperative prediction of cardiac complications. Receiver operating curve analysis defined a left ventricular ejection fraction of less than 50% as an appropriate threshold for defining patients at high risk, with a sensitivity of 78% and a specificity of 81% in the identification of patients who had cardiac morbidity. The positive predictive value was 27%, and the negative predictive value was 97%. The economic impact of outpatient echocardiography was well below that of dipyridamole myocardial scintigraphy or dobutamine stress echocardiography. CONCLUSIONS: Outpatient echocardiography appears to offer a cost-efficient compromise between clinical criteria alone and provocative cardiac testing such as dipyridamole myocardial scintigraphy and dobutamine stress echocardiography in the preoperative screening of patients undergoing peripheral vascular surgical procedures.

Thrombus formation on polytetrafluoroethylene surfaces: the importance of von Willebrand factor.

The importance of von Willebrand factor (vWf) in the formation of platelet-fibrin thrombi on expanded polytetrafluoroethylene (ePTFE) surfaces was studied in an in vitro system, perfusing non-anticoagulated human blood over ePTFE grafts for 3 min at varying shear rates (100, 500 and 1500/s shear). Platelet (111In) and fibrin (125I) deposition was assessed on ePTFE surfaces in the presence and relative absence of vWf, achieved by use of polyclonal anti-vWf antibody (anti-vWf Ab). A total of 29 perfusions were performed. Increasing shear rate was associated with greater platelet deposition in the presence of vWf (p < 0.001). This shear-dependent rise in platelet deposition was not observed when vWf was blocked by anti-vWf Ab (P < 0.1), confirming the role of vWf in platelet deposition at high shear rates. Fibrin deposition increased with increasing shear rate in the presence of vWf (P < 0.01). Inhibiting vWf abolished the shear-dependent increase in fibrin deposition. These data suggest that vWf plays a critical role in platelet and fibrin thrombus formation on ePTFE surfaces. These effects are particularly important under conditions of high shear rate. These mechanisms may lead to the observed pathologic thrombus formation and platelet-dependent neointimal processes occurring at areas of high shear rate within the anastomotic regions of ePTFE grafts.

Economic implications of thrombolysis or operation as the initial treatment modality in acute peripheral arterial occlusion.

BACKGROUND: Thrombolytic agents have been used to treat arterial occlusion for almost 40 years. Recently, an investigation of the costs associated with two treatment options for acute peripheral arterial occlusions, thrombolysis and surgical intervention, was completed. The availability of hospital cost data for patients enrolled in the thrombolytic and operative treatment groups provided a basis with which to accurately assess the financial impact of the different treatment strategies, both from a purely financial standpoint and in relation to outcome. METHODS: The patient base was composed of 114 patients with acute limb ischemia of less than 7 days' duration. The patients were randomly assigned to receive urokinase (n = 57) or to undergo an operation (n = 57) as the initial therapeutic intervention. Patients in the thrombolytic group underwent standard intraarterial diagnostic arteriography, and patients with embolic events, in whom complete lysis of all embolic and propagated thrombotic material was achieved, were subsequently treated with heparin and long-term warfarin (Coumadin) therapy. The economic analysis was undertaken after the completion of the trial. Statistical comparisons between groups were made with the Student t test for continuous, normally distributed data. Mortality and limb salvage rates were calculated from Kaplan-Meier curves, appropriate for the censored nature of the data. RESULTS: The total treatment costs did not differ significantly between the two treatment groups ($22,171 +/- $4,959 in the thrombolytic group and $19,775 +/- $5,253 in the operative group). The total hospital charges were similar between the two groups. Overall, the total charges were remarkably similar between the two treatment groups, averaging $40,823 +/- $8,764 in the thrombolytic group and $41,930 +/- $10,398 in the operative group. CONCLUSIONS: An economic analysis of the data confirmed that the total economic impact of thrombolysis approximated that of initial operative therapy. The improved clinical outcome in patients treated with thrombolysis suggests that this modality may be appropriate as the initial therapeutic intervention in the select group of patients seen within the first few hours of an acute peripheral arterial occlusive event.

Differential mechanisms of failure of autogenous and non-autogenous bypass conduits: an assessment following successful graft thrombolysis.

The advent of graft thrombolysis has provided an objective means for evaluating the etiology of graft occlusion. Over a 10-year period, intra-arterial urokinase (102 cases) or streptokinase (seven cases) was used in 109 infrainguinal conduits (30 autogenous and 79 non-autogenous) that failed 30 days or more after implantation. Thrombolysis was not achieved in 19 additional graft occlusions; these cases were excluded from study because of an inability to define the mechanism of failure. Non-invasive laboratory data were available within 6 months of graft occlusion in 82 (75%) of the cases, with Doppler segmental studies in 80 cases (73%) and duplex ultrasonography studies in 39 cases (36%). Pre-failure non-invasive laboratory abnormalities were detected more frequently in autogenous grafts (21 of 24 patients, 88%), while non-autogenous grafts usually occluded without prior hemodynamic change (11 of 58 patients had abnormalities, 19%) (P < 0.001). Thrombolysis uncovered anatomic defects responsible for thrombosis in 27 (90%) of 30 autogenous grafts compared with only 32 (41%) of non-autogenous conduits (P < 0.001). The most common lesions underlying autogenous graft failure comprised stenoses within the body of the graft (11 cases, 37%), while the most common lesions in failed non-autogenous grafts appeared to be stenoses at an anastomosis (21 cases, 27%). Thus, the mechanisms underlying the late failure of autogenous and non-autogenous grafts differ markedly; autogenous grafts most commonly fail as a result of the gradual development of lesions intrinsic to the graft, while non-autogenous grafts fail precipitously, presumably as a result of some non-anatomic mechanism.