Biomedical subjects

K A Illig

Publications and source records attributed to K A Illig.

At least 19 recordsLinked to original sources

PubMed2001

Reduction in wound morbidity rates following endoscopic saphenous vein harvest.

To determine whether less-invasive saphenous vein harvest reduces morbidity in patients undergoing infrainguinal bypass, we retrospectively compared 61 patients undergoing endoscopic harvest (ENDO) with 49 patients undergoing conventional harvest (OPEN) over the past 13 months. Patients were classified as potential short-stay if adjunctive suprainguinal inflow procedures or foot amputations were not required and the patient was ambulatory prior to elective operation. Mean endoscopic harvest time was 50+/-18 (range 25-90) min, and no more than three 5-cm incisions were required in 87% of cases. Szilagyi class II or III wound complications occurred after 1 of the 61 (2%) ENDO procedures and 7 of the 49 (14%) OPEN (p < 0.01), and any complication occurred in 13 (21%) vs. 25 (51%) of ENDO and OPEN procedures, respectively (p < 0.002). Mean postoperative length of stay was significantly shorter in the 24 short-stay ENDO (4.0+/-2.4 days) vs. 25 short-stay OPEN (6.0+/-3.2 days) patients (p < 0.02). Thirty-day patency rates between the two groups were not different. Endoscopic saphenous vein harvest is associated with a reduced incidence of serious wound complications and, in selected patients, shortened postoperative hospital stay.

Aged↗

PubMed2001

Combined free tissue transfer and infrainguinal bypass graft: an alternative to major amputation in selected patients.

OBJECTIVES: The purpose of this study was to document outcome and adverse prognostic factors in patients requiring combined free tissue transfer and distal bypass grafting for otherwise nonreconstructible infrainguinal arterial occlusive disease and advanced tissue necrosis. METHODS: Between July 1990 and November 1999, 65 patients, all of whom would have required at least below-knee amputation, underwent free tissue transfer in conjunction with infrainguinal bypass grafting at the University of Rochester. Preoperative variables were assessed for their influence on outcome with chi(2) and outcome with life-table analysis with Cox proportionate hazard testing. RESULTS: Free tissue transfer was performed synchronously with arterial reconstruction with autologous vein in 49 patients and after a previous functioning venous bypass graft in 16 patients. The 30-day mortality rate was 5%, and major complications occurred in another 16% of patients. Flap location, weight-bearing status, preexisting osteomyelitis, and the timing of bypass grafting relative to flap construction had no effect on outcome. All five free flap failures occurred within the first 30 days. All other flaps subsequently survived, even in seven patients whose bypass grafts thrombosed. Five-year limb salvage and patient survival rates were 57% and 60%, respectively, and 65% of patients regained meaningful ambulation. The combination of diabetes and dialysis-dependent renal failure was the strongest predictor of overall limb loss (P <.005; relative risk = 4.0), and diabetes alone was the strongest predictor of death (P <.02; relative risk = 5.2). CONCLUSION: Free tissue transfer combined with infrainguinal bypass grafting in selected patients is safe and effective. The combination of diabetes and chronic renal insufficiency, particularly the need for dialysis, is a powerful predictor of failure and should be considered a strong contraindication for this procedure.

Amputation, Surgical↗

PubMed2000

Irradiation for intimal hyperplasia: implications for peripheral arterial bypass.

Irradiation has been shown to inhibit postangioplasty intimal hyperplasia ("restenosis") in unbranched tubes. It seems likely that irradiation will similarly be able to inhibit intimal hyperplasia after a surgical anastomosis at a biochemical and cellular level, but whether it will produce a clinically relevant or even clinically detectable difference is unproved. One possibility is that no clinical effect may occur; the search for a "cure" for intimal hyperplasia has been long and, as yet, unsuccessful. On the other hand, if a strong effect without insurmountable logistical problems could be produced, one major cause of bypass graft failure would be preventable. Not only would the incidence of late graft occlusion, need for reoperation, and limb loss be reduced, but, if patency of prosthetics could be sufficiently improved, the initial operation could be made much easier, faster, and perhaps safer.

Angioplasty, Balloon↗

PubMed2000

An endoluminal method of hemorrhage control and repair of ruptured abdominal aortic aneurysms.

PURPOSE: To report our initial experience with endovascular grafting to treat ruptured abdominal aortic aneurysms (AAAs). METHODS: Three consecutive patients with severe comorbid illnesses and symptoms of aneurysm rupture and hemodynamic instability were treated with aortomonoiliac grafts. The Z-stent-based devices were implanted with the assistance of an occlusion balloon placed in the distal descending thoracic aorta. RESULTS: All patients survived the procedure with successfully excluded AAAs. Two patients had relatively short hospital stays (4 and 14 days), while the third required prolonged treatment for pre-existing conditions. All patients required blood transfusions; 2 developed significant coagulopathies. Definitive management was delayed significantly by imaging protocols and graft construction. CONCLUSIONS: Endovascular repair of ruptured aortic aneurysms is feasible. Proximal aortic control is readily attainable with the use of an aortic occlusion balloon placed through the left axillary artery. The absence of a laparotomy, extensive retroperitoneal dissection, and aortic cross-clamping likely contributes to patient survival; however, the delay in operative therapy to obtain adequate imaging and construct an endograft could be a hindrance to the ultimate success of this approach. The concepts of alternative aortic imaging techniques and endograft design, construction, and storage must be addressed.

Aged↗

PubMed2000

Unrecognized carotid artery stenosis discovered by calcifications on a panoramic radiograph.

BACKGROUND: Approximately 730,000 strokes occur each year in the United States, costing an estimated $40 billion annually. One-half of all strokes are the result of atherosclerotic plaques found in the carotid artery. Such plaques frequently are heavily calcified and can be identified on a panoramic radiograph by the incidental finding of calcifications overlying the carotid bifurcation. CASE DESCRIPTION: The authors found that a 67-year-old asymptomatic woman had calcium deposits overlying both carotid bifurcation regions on a panoramic radiograph. Subsequent duplex ultrasonic examination indicated bilateral, high-grade carotid arterial stenoses. The patient underwent uneventful bilateral carotid endarterectomy. CLINICAL IMPLICATIONS: The patient had critical carotid arterial stenoses associated with significant risk of stroke that had not been identified otherwise. The findings on the panoramic radiograph led to appropriate and potentially life-saving treatment. While the positive predictive value of this finding has yet to be defined, the authors believe that calcifications overlying the carotid system region seen on panoramic radiography in an asymptomatic patient should be followed by formal evaluation of the carotid bifurcation.

Aged↗

PubMed1999

Photoplethysmography and calf muscle pump function after subfascial endoscopic perforator ligation.

OBJECTIVE: Subfascial endoscopic perforator surgery (SEPS) results in acceptable healing and recurrence rates. The role of hemodynamic venous testing in this situation, however, is poorly understood and inconsistently used. Our ongoing experience was reviewed to explore how SEPS affects the photoplethysmographic assessment of the leg. METHODS: Preoperative and postoperative venous refill times (VRTs) were measured with photoplethysmography in 30 limbs in 28 patients who underwent SEPS and superficial ablation, when indicated, with complete clearing of the anterolateral surface of the tibia, thus opening the deep posterior compartment from mid calf to close to the malleolus. Postoperative healing and duplex scanning were used to assess clinical and anatomic success, respectively. The VRTs were classified as "interpretable" if the leg emptied or "uninterpretable" if the calf could not empty. The "interpretable" study results were further classified as "normal" if the refill took 20 seconds or more or "abnormal" if less. RESULTS: Before the patients underwent SEPS, six study results (20%) showed inability of the calf to empty and thus were judged uninterpretable. After the patients underwent SEPS, 12 study results (40%) were uninterpretable (NS; P =.09 with the chi(2) test). Of the 24 preoperative interpretable study results, two (8%) were normal, and of the 18 postoperative interpretable study results, seven (39%) were normal (P <.03). With the consideration of only interpretable study results, the mean VRT increased slightly from 12.0 +/- 5.1 seconds (mean +/- standard deviation) to 14.3 +/- 8.1 seconds (NS). Seventeen of 19 ulcers (89%) had healed at a mean follow-up period of 8.6 +/- 4.8 months. CONCLUSION: Although VRT is unpredictably affected by SEPS, the most consistent finding is the inability of the calf to empty, which invalidates the remainder of the test. In addition, most ulcers heal, even with uninterpretable or abnormal postoperative VRTs. This suggests that photoplethysmography is a poor method of assessment of venous reflux after SEPS.

Adult↗

PubMed1999

Intracerebral hemorrhage after carotid endarterectomy: incidence, contribution to neurologic morbidity, and predictive factors.

PURPOSE: With a diminishing rate of cardiac and neurologic events after carotid endarterectomy, intracerebral hemorrhage is gaining increasing importance as a cause of perioperative morbidity and mortality. To date, information has been largely anecdotal, and there has been no comparison with a control group of patients. METHODS: The records of all patients experiencing symptomatic intracerebral hemorrhage after carotid endarterectomy were reviewed and compared with data from 50 randomly selected patients who did not experience intracranial bleeding. Univariate analyses were performed, using the Fisher exact test for dichotomous data and the Student t test for continuous data. RESULTS: During a 6-year period, symptomatic intracranial hemorrhage developed in 11 (0.75%) of 1471 patients undergoing carotid endarterectomy, accounting for 35% of the 31 total perioperative neurologic events. Hemorrhage occurred a median of 3 days postoperatively (range, 0 to 18 days). Signs and symptoms included hypertension in all 11 patients, headache in 7 conscious patients (64%), and bradycardia in 6 patients (55%). Massive hemorrhage with herniation and death occurred in 4 patients (36%). Moderate hemorrhage developed in 5 patients (45%); 3 of these patients had partial recovery, and 2 had complete recovery. Petechial hemorrhage occurred in the remaining 2 patients (18%), 1 with partial and 1 with complete recovery. In comparison with the control group, there were no differences in respect to sex, indication for operation, smoking or diabetic history, and antiplatelet therapy or perioperative heparin management. Patients with intracranial hemorrhage were, however, younger, more frequently hypertensive, had a higher degree of ipsilateral and contralateral carotid stenosis, and had a higher rate of contralateral carotid occlusion. CONCLUSION: Intracranial hemorrhage occurs with notable frequency after carotid endarterectomy and accounts for a significant proportion of neurologic morbidity and mortality. Younger patients, hypertensive patients, and patients with severe cerebrovascular occlusive disease appear to be at greatest risk for the complication.

Age Factors↗

PubMed1999

Prosthetic above-knee femoropopliteal bypass.

One of the classic and as yet unresolved arguments in vascular surgery is whether using prosthetic for a first-time above-knee femoropopliteal bypass, to "save the vein" for a later, more distal bypass, is of net benefit. Most of the arguments supporting use of prosthetic for a first bypass in this situation are, in fact, not supported by the literature, whereas most of the arguments in favor of using vein first are. In addition, decision analysis shows that overall amputation-free survival and number of operative procedures required are clearly better if vein is used first under essentially all conditions--the overwhelmingly strongest determinant of outcome is patency of the first bypass, and the superior patency of initial bypass with vein mathematically outweighs the ability of the "preserved" vein to salvage failures after an initial bypass with prosthetic. Theoretical, empirical, and mathematical arguments all strongly favor preferential use of vein for a first bypass to the above-knee popliteal artery.

Blood Vessel Prosthesis Implantation↗

PubMed1998

Fetal internal iliac artery: case report and embryologic review.

A 25-year-old woman with anomalous circulation to the right leg was seen with a symptomatic aneurysm of the abnormal vessel. The artery, which did share some features of the classic persistent sciatic artery, also had important differences that were not previously described in the literature. The patient manifested several associated vascular and nonvascular congenital anomalies. She underwent resection of the aneurysm and primary operative repair of the artery without difficulty. An embryologic interpretation is offered, and the clinical implications and management strategy are discussed.

Adult↗

PubMed1998

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.

Aged↗

PubMed1998

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.

Brain Ischemia↗

PubMed1998

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.

Adolescent↗

PubMed1997

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.

Aged↗

PubMed1997

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.

Aorta, Abdominal↗

PubMed1997

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.

Aged↗

PubMed1997

Are prophylactic antibiotics required for elective laparoscopic cholecystectomy?

BACKGROUND: Some clinicians administer prophylactic antibiotics routinely before laparoscopic cholecystectomy, and the results of some of the studies in the literature support this practice. We conducted a prospective randomized trial to determine whether administration of prophylactic antibiotics is necessary during routine laparoscopic cholecystectomy in low-risk patients. STUDY DESIGN: Two hundred fifty patients without evidence of acute inflammation, common duct stones, or other indications for antibiotics were randomized to receive three perioperative doses of cefazolin or no prophylaxis and followed up for complications up to 30 days postoperatively. The primary end point was the occurrence of a major infectious complication, defined as that causing a systemic response, delaying discharge, or leading to readmission. Minor infectious problems were also noted, defined as those causing local symptoms only. RESULTS: One hundred twenty-eight patients were randomized to receive prophylactic antibiotics (PA group), 122 to receive none (NONE group; two patients in this group were actually given preoperative antibiotics). Only one major complication occurred (in a patient in the NONE group), an abscess in the presence of a bile leak, despite the administration of antibiotics when the leak was discovered several days before infectious problems arose. There were four minor problems: two lower urinary tract infections and one superficial wound infection in a NONE patient and one urinary tract infection in a PA patient (not significant); all were easily managed. The prophylactic antibiotics did not sterilize the bile, and infectious complications were not associated with weight, inflammation found at the time of operation, reported stone or bile spill-age, or conversion to open operation. CONCLUSIONS: Prophylactic antibiotics are not necessary for elective laparoscopic cholecystectomy in low-risk patients.

Antibiotic Prophylaxis↗

PubMed1997

Optimal diagnosis of splenic vein thrombosis: brief clinical report.

The presence of splenic vein thrombosis is sometimes very difficult to diagnose. We present a patient in whom the splenic vein was thought to be patent by ultrasound and conventional celiac angiography. Because of high clinical suspicion and continued bleeding, he underwent a selective intra-arterial digital splenic angiogram. The venous phase clearly showed proximal (hilar) splenic vein occlusion with filling via collaterals in real time. Splenectomy confirmed the diagnosis. We believe that a selective intra-arterial digital splenic angiogram is the radiographic study of choice for suspected splenic vein thrombosis.

Aged↗

PubMed1996

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.

Blood Flow Velocity↗