Use of intravascular ultrasound as a "Quality Control" technique during carotid stent-angioplasty: are there risks to its use?

Intravascular ultrasound (IVUS) provides high-resolution vessel imaging and has been shown to improve clinical outcomes when used to assess the technical result of peripheral angioplasty procedures. Our vascular group compared anatomic and clinical outcomes of carotid artery stent-angioplasty (CAS) performed with angiogram monitoring alone, or in combination with IVUS imaging to select stent/balloon diameter and interrogate stent deployment region for residual stenosis. A retrospective review of our carotid stent registry (N=306) identified 220 CAS procedures performed with either a digital C-arm fluoroscopy alone (N=110) or in conjunction with IVUS (N=110) with at least 6-month of clinical follow-up. Outcome measures of procedure time, angioplasty balloon diameter, contrast dye volume, Duplex surveillance testing for recurrent stenosis, and procedure event (death, cardiac, neurologic) rates were compared to assess the risks and benefits of IVUS. All procedures utilized a cerebral protection device deployed prior to IVUS imaging. Procedure times were similar, but IVUS usage resulted in lower (P<0.05) contrast agent volumes due to fewer angiogram runs for stent sizing and verification of adequate stent deployment. IVUS imaging resulted in the use of larger diameter balloons (typically 6 mm) for final stent angioplasty based on distal internal carotid artery (ICA) dia measurements, and identified (P<0.01) more residual stent abnormalities (N=12, 11%) versus CAS with angiogram assessment alone (N=2, 1.8%). No procedural or 30-day cardiac events or deaths occurred. The overall stroke rate was 0.9%; two events (stroke-1; reperfusion injury-1) in the angio+IVUS group (1.8%) and none in the angio alone group. Duplex ultrasound surveillance following CAS demonstrated a higher (P<0.01) incidence of >50% diameter-reducing in-stent stenosis in the angio alone group (11% vs 7% at 1 month ; 24% vs 6% at last surveillance; mean 36 moontha; range: 6-66 months). The quality control of the CAS procedure was enhanced by IVUS imaging which directed stent /balloon sizing and was more accurate than angiography in confirming adequate stent expansion. No IVUS related adverse events occurred. Based on the anatomic information provided by IVUS, larger diameter angioplasty balloons were used which correlated with less residual stenosis after CAS based on duplex ultrasound testing.

Carotid intervention prior to or during coronary artery bypass grafting. When is it necessary?

Management of patients with advanced atherosclerosis involving the extra-cranial carotid and coronary arteries should be individualized based on symptoms and disease severity. A liberal policy to identify high-grade carotid stenosis using duplex ultrasound testing prior to coronary revascularization is recommended. Carotid intervention is efficacious for stroke reduction in patients with severe (>70% diameter reduction), bilateral internal carotid artery disease, especially if testing indicates abnormal cerebral perfusion via the circle of Willis. The morbidity of a combined carotid-coronary revascularization procedure should be less than 5%, but higher stroke and death rates can be expected in urgent cases with recent hemispheric symptoms. Patients with symptomatic >50% internal carotid artery stenosis should be considered for carotid endarterectomy at the time of coronary revascularization. Carotid angioplasty with cerebral protection is also an appropriate option in "high-risk" cardiac patients, especially in vascular centers with expertise and experience in performing this procedure. A policy of carotid endarterectomy prior to coronary bypass grafting is justified only in patients with stable coronary disease, good ejection fraction, and is best-performed using regional anesthesia.

Utility of duplex surveillance following iliac artery angioplasty and primary stenting

PURPOSE

To evaluate the clinical outcome and patency rates after iliac artery angioplasty and primary stenting using a noninvasive surveillance protocol that includes duplex ultrasonography.

METHODS

Sixty-seven patients (64 men; mean age 61 +/- 9 years, range 45-83) underwent stenting of 84 iliac systems for claudication (63%), rest pain (9%), tissue loss (20%), or failing lower limb bypass graft (8%). The surveillance algorithm included aortoiliac duplex scanning within 1 month and serial limb pressure measurements and femoral artery waveform analyses during follow-up. Iliac systems with a peak systolic velocity >300 cm/s and velocity ratio >2.0 by duplex and/or symptomatic or hemodynamic deterioration were considered failing and an indication for angiography.

RESULTS

During intermediate-term follow-up ranging to 36 months (mean 12), life table primary, assisted primary, and secondary patency rates for the treated iliac systems were 78%, 90%, and 98%, respectively, at 18 months. Assisted primary iliac system patency at 18 months was significantly worse in the 20 (24%) limbs having an outflow bypass done with or prior to iliac stenting (83% versus 100% without bypass, p = 0.01). Indirect clinical indicators found 17 (20%) suspected failing iliac systems, in which duplex imaging correctly identified 5 of 6 recurrent iliac stenoses and facilitated secondary endovascular intervention. Three (4%) stent occlusions occurred in the treated iliac systems despite surveillance.

CONCLUSIONS

Duplex surveillance after iliac stenting localizes failing inflow segments, optimizes assisted patency of the treated iliac system, and possesses greatest utility in patients with multilevel occlusive disease and outflow reconstructions.

Expanded application of in situ replacement for prosthetic graft infection

PURPOSE

The purpose of this study was to analyze the outcome of an individualized treatment algorithm for prosthetic graft infection, including the application of in situ graft replacement, based on clinical presentation, extent of graft infection, and microbiology.

METHODS

There was a retrospective review (1991-2000) of 119 patients with 68 aortoiliofemoral or 51 extracavitary (infrainguinal, 19; axillofemoral, 16; femorofemoral, 16) prosthetic graft infections presenting more than 3 months (range, 3-136 months) after implantation/revision. The treatment algorithm consisted of graft excision with or without ex situ bypass grafts for patients presenting with sepsis or graft-enteric erosion, whereas in situ replacement (autogenous vein, rifampin-bonded polyester, polytetrafluoroethylene [PTFE]) was used in patients with less virulent gram-positive graft infection, in particular infections caused by Staphylococcus epidermidis. Outcomes (death, limb loss, recurrent infection) were correlated with treatment type and infecting organism.

RESULTS

In situ replacement was used in 52% of aortoiliofemoral (autogenous vein, 10; rifampin-bonded polyester, 6; PTFE, 9) and 80% of extracavitary (autogenous vein, 26; PTFE, 9; rifampin, 6) graft infections. Total graft excision with ex situ bypass was performed in 34 patients, including 21 patients with graft-enteric erosion/fistula, with a 21% operative mortality and 9% amputation rate. In situ graft replacement was used to treat 76 graft infections with a 30-day operative mortality rate of 4% and an amputation rate of 2%. Graft excision alone was performed in nine patients with one 30-day death. Gram-positive cocci were the prevalent infecting organisms of both intracavitary (59% of isolates) and extracavitary (76% of isolates) graft infections. S epidermidis was the infecting organism in 40% of patients, accounting for the expanded application of in situ prosthetic replacement using a rifampin-bonded polyester or PTFE prosthesis. During the mean follow-up interval of 26 months, recurrent graft infection developed in 3% (1 of 34) of patients after conventional treatment, 3% (1 of 36) patients after in situ vein replacement, and 10% (4 of 40) patients after in situ prosthetic graft replacement (P >.05). Failure of in situ replacement procedures was the result of virulent and antibiotic-resistant bacterial strains.

CONCLUSIONS

In situ replacement was a safe and durable option in most (64%) patients presenting with prosthetic graft infection. In situ replacement with a rifampin-bonded graft was effective for S epidermidis graft infection, but when the entire prosthesis is involved with either a biofilm or invasive perigraft infection, in situ autogenous vein replacement is preferred. Virulent graft infections presenting with sepsis, anastomotic dehiscence, or graft enteric fistula should continue to be treated with total graft excision, and if feasible, staged ex situ bypass graft.

Primary axillary-subclavian venous thrombosis: is aggressive surgical intervention justified?

Multimodal (thrombolysis, surgical decompression, venous reconstruction, oral anticoagulation) treatment of primary axillary-subclavian venous thrombosis was reviewed to assess the impact of venous patency on functional outcome. Since 1996, 7 patients (6 men, 1 woman) of ages 16-53 years (mean 33 years) presented with symptomatic acute axillosubclavian venous thrombosis as a result of a recent athletic or strenuous arm activity. Five patients had undergone previous (>2 weeks) catheter-directed thrombolysis and venous angioplasty. Diagnostic contrast venography followed by repeat catheter-directed thrombolysis demonstrated abnormal (residual stenosis [n=6] or occlusion [n=1]) axillosubclavian venous segments in all patients. Surgical intervention was performed at a mean interval of 7 days (range 1-19 days) after thrombolysis and consisted of thoracic outlet decompression with scalenectomy and 1st rib resection via a paraclavicular (n=4) or supraclavicular (n=3) approach. Medial claviculectomy or cervical rib resection was performed in 2 patients. Concomitant venous surgery was performed in all patients to restore normal venous patency by circumferential venolysis (n=7) and balloon catheter thrombectomy (n=3), or vein-patch angioplasty (n=2), or endovenectomy (n=5), or internal jugular transposition (n=2). Postoperative venous duplex testing beyond 1 month identified recurrent thrombosis in 4 patients despite therapeutic oral anticoagulation. Subsequent venous recanalization was documented in 3 patients. Poor functional outcome was associated with an occluded venous repair and extensive venous thrombosis on initial presentation. A patent or recanalized venous repair present in 6 of 7 patients was associated with good functional outcome and may justify multimodal intervention in patients with primary axillosubclavian effort thrombosis presenting with recurrent thrombosis and significant residual disease after thrombolysis.

Use of rifampin-soaked gelatin-sealed polyester grafts for in situ treatment of primary aortic and vascular prosthetic infections

BACKGROUND

In situ treatment of artery/graft infection has distinct advantages compared to vessel excision and extra-anatomic bypass procedures. Based on animal studies of a rifampin-soaked, gelatin-impregnated polyester graft that demonstrated prolonged in vivo antibacterial activity, this antibiotic-bonded graft was used selectively in patients for in situ treatment of low-grade Gram-positive prosthetic graft infections or primary aortic infections not amenable to excision and ex situ bypass.

METHODS

In a 5-year period (1995-1999), 27 patients with prosthetic graft infection (aortofemoral, n = 18, femorofemoral, n = 3; axillofemoral, n = 1) or primary aortic infection (mycotic aneurysm, n = 3; infected AAA, n = 2) underwent excision of the infected vessel and in situ replacement with a rifampin soaked (45-60 mg/ml for 15 min) gelatin-impregnated polyester graft. All prosthetic graft infections were low grade in nature, caused Gram-positive bacteria (Staphylococcus epidermidis, 16; Staphylococcus aureus, 5; Streptococcus, 1), and were treated electively. Patients with mycotic aortic aneurysm presented with sepsis and underwent urgent or emergent surgery.

RESULTS

Two (8%) patients died-1 as a result of a ruptured Salmonella mycotic aortic aneurysm and the other from methicillin-resistant S. aureus infection following deep vein replacement of an in situ replaced femorofemoral graft. No amputations or late deaths as the result of vascular infection occurred in the 25 surviving patients. Two patients developed recurrent infection caused by a rifampin-resistant S. epidermidis in a replaced aortofemoral graft limb and were successfully treated with graft excision and in situ autogenous vein replacement. Eighteen patients remain alive and clinically free of infection after a mean follow-up interval of 17 months.

CONCLUSIONS

In situ replacement treatment using a rifampin-bonded prosthetic graft for low-grade staphylococcal arterial infection was safe, durable, and associated with eradication of clinical signs of infection. Failure of this therapy was the result of virulent and antibiotic-resistant bacterial strains.

Magnetic resonance angiography is an accurate imaging adjunct to duplex ultrasound scan in patient selection for carotid endarterectomy

PURPOSE

The purpose of this study was to evaluate the accuracy of magnetic resonance angiography (MRA) for categorizing the severity of carotid disease relative to duplex ultrasound scan and cerebral contrast arteriography (CA) to determine if MRA imaging could replace the need for cerebral angiography in cases of indeterminate or inadequate duplex scan imaging.

METHODS

Seventy-four carotid bifurcations in 40 patients undergoing 45 carotid endarterectomies from 1996 to 1998 were imaged with duplex ultrasound scan; MRA (two-dimensional neck and three-dimensional intracranial, time-of-flight technique); and biplanar, digital subtraction cerebral arteriography. Studies were blindly reviewed by one reader who used established threshold velocity criteria for the duplex scan and the North American Symptomatic Carotid Endarterectomy Trial method for MRA and CA to determine the percentage of diameter reduction of the internal carotid artery (ICA). Disease severity was grouped into four categories (< 50%, 50%-74%, 75%-99% stenosis and occlusion), and the results of MRA and duplex ultrasound scan were compared with CA.

RESULTS

Sensitivity, specificity, positive predictive value, and negative predictive value for detection of > 50% ICA stenosis were 100%, 96%, 98%, and 100% for MRA and 100%, 72%, 88%, and 100% for duplex ultrasound scan, respectively; similarly, for detection of > 75% ICA stenosis values were 100%, 77%, 76%, and 100% for MRA and 90%, 74%, 72%, and 91% for duplex ultrasound scan, respectively. Both MRA and duplex ultrasound scan accurately differentiated all cases of > 95% stenosis (n = 7) from occlusion (n = 4). Short length ICA flow gaps were present on MRA in all cases of 75% to 99% stenosis and one half of cases of CA-defined 50% to 74% stenosis. In patients with 50% to 74% stenosis, the mean angiographic stenosis was significantly greater when a flow gap was present on MRA (64% +/- 6%) versus no flow gap (57% +/- 7%) (P =.04). There was overall agreement among duplex ultrasound scan, MRA, and CA in 73% of carotids imaged. Of the 24% discordant results between MRA and duplex ultrasound scan, MRA correctly predicted disease severity in all cases, and inaccurate duplex ultrasound scan results were due to overestimation in 83% of cases. The operative plan was altered by CA findings in only one patient (2%) after duplex ultrasound scan and MRA.

CONCLUSIONS

MRA can accurately categorize the severity of carotid occlusive disease. Duplex ultrasound scan facilitates patient selection for carotid endarterectomy in most cases, but adjunct use of MRA improves diagnostic accuracy for > 75% stenoses and may obviate the need for cerebral arteriography when duplex scan results are inconclusive or demonstrate borderline disease severity.

Intraoperative duplex monitoring of infrainguinal vein bypass procedures

PURPOSE

The purpose of this study was to evaluate intraoperative duplex scanning of infrainguinal vein bypass grafts to detect technical and hemodynamic problems, monitor their repair, and correlate findings with the incidence of thrombosis and stenosis repair rates within 90 days of operation.

METHODS

Color duplex scanning was used at operation to assess vein/anastomotic patency and velocity spectra waveforms of 626 infrainguinal vein bypass grafts (in situ saphenous, 228 grafts; nonreversed translocated saphenous, 170 grafts; reversed saphenous, 147 grafts; alternative [arm, lesser saphenous], 81 grafts) to the popliteal (n = 267 grafts), infrageniculate (n = 323 grafts), or pedal artery (n = 36 grafts). The entire bypass graft was scanned after intragraft injection of papaverine hydrochloride (30-60 mg) to augment graft flow. Vein/anastomotic/artery segments with velocity spectra that indicate highly disturbed flow (peak systolic velocity, >180 cm/sec; spectral broadening; velocity ratio at site, >3) were revised. Grafts with a low peak systolic velocity less than 30 to 40 cm/s and high outflow resistance (absent diastolic flow) underwent procedures (distal arteriovenous fistula, sequential bypass grafting) to augment flow; if this was not possible, the grafts were treated with an antithrombotic regimen, including heparin, dextran, and antiplatelet therapy.

RESULTS

Duplex scanning prompted revision of 104 lesions in 96 (15%) bypass grafts, including 82 vein/anastomotic stenoses, 17 vein segments with platelet thrombus, and 5 low-flow grafts. Revision rate was highest (P <.01) for alternative vein bypass grafts (27%) compared with the other grafting methods (reversed vein bypass grafts, 10%; nonreversed translocated, 13%; in situ, 16%). A normal intraoperative scan on initial imaging (n = 464 scans) or after revision (n = 67 scans) was associated with a 30-day thrombosis rate of 0.2% and a revision rate of 0.8% for duplex-detected stenosis (peak systolic velocity, >300 cm/s; velocity ratio, >3.5). By comparison, 20 of 95 bypass grafts (21%) with a residual (n = 29 grafts) or unrepaired duplex stenosis (n = 53 grafts) or low flow (n = 13 grafts) had a corrective procedure for graft thrombosis (n = eight grafts) or stenosis (n = 12 grafts; P <.001). Overall, 8% of patients with bypass grafts underwent a corrective procedure within 90 days of operation. Secondary graft patency was 99.4% at 30 days and 98.8% at 90 days (eight graft failures).

CONCLUSION

The observed 15% intraoperative revision rate coupled with a low 90-day failure/revision rate (2.5%) for bypasses with normal papaverine-augmented duplex scans supports the routine use of this diagnostic modality to enhance the precision and early results of infrainguinal vein bypass procedures.

Duplex imaging of lower extremity bypasses, angioplasties, and stents

Duplex scan surveillance after lower extremity bypass and endovascular interventions can have a favorable impact on outcome. Its application during an arterial intervention to exclude technical or hemodynamic abnormalities and as part of a postoperative surveillance program to detect stenosis has been shown to improve patency. Results of duplex imaging can identify the arterial reconstruction at high risk of failure/thrombosis, which requires more intensive surveillance. Based on stenosis severity and anatomy, duplex scanning can suggest which repair technique (open surgery vs percutaneous balloon angioplasty [PTA]) is more appropriate. The use of duplex imaging during PTA of graft or peripheral artery stenoses (duplex-monitored balloon angioplasty) is recommended to verify normalization of velocity spectra, because this end point is associated with improved stenosis-free patency. A duplex surveillance program combined with correction of progressively stenotic lesions is recommended after lower limb bypass and PTA.

A rational algorithm for duplex scan surveillance after carotid endarterectomy

PURPOSE

This study was undertaken to determine the appropriate timing and frequency of duplex ultrasound scanning after carotid endarterectomy (CEA) for the detection of high-grade stenosis caused by recurrent carotid stenosis or contralateral atherosclerotic disease progression.

METHODS

In 221 patients who underwent 242 CEAs, duplex scanning was performed before, during, and after operation (in 3-month to 6-month intervals). High-grade internal carotid artery (ICA) stenosis (peak systolic velocity, >300 cm/s; diastolic velocity, >125 cm/s; ICA/common carotid artery ratio, >4) prompted the recommendation for repair. An average of four postoperative scanning procedures was performed during a mean follow-up period of 27.4 months.

RESULTS

Intraoperative duplex scan results prompted the immediate revision of 12 repairs (4.9%), and one perioperative stroke (<1%) occurred. Six CEAs (2.7%) had asymptomatic recurrent stenosis (>50% diameter-reduction [DR]; systolic velocity, >125 cm/s) develop. Only one of six patients had >75% DR stenosis develop and underwent reoperation (<1% yield for CEA surveillance). The yield of surveillance of the unoperated ICA was higher (P =.003), and 12% of unoperated sides had progressive stenosis (n = 21) or occlusion (n = 3) develop, which led to seven CEAs for high-grade stenosis. Disease progression to >75% DR stenosis was five times as frequent (P =.002) in patients with >50% DR stenosis initially. All patients but one who required contralateral endarterectomy for disease progression had >50% ICA stenosis when first seen. During the follow-up period, no disabling strokes ipsilateral to an operated carotid artery occurred, but three strokes occurred in the hemisphere of the contralateral unoperated ICA.

CONCLUSION

The yield of duplex scan surveillance after CEA was low. Only 13 patients (5.9%) had severe disease develop to warrant additional intervention. Progression of contralateral disease rather than restenosis was the most common abnormality that was identified. Duplex scanning at 1-year to 2-year intervals after CEA is adequate when a technically precise repair is achieved and minimal contralateral disease (<50% DR) is present. A policy of duplex scan surveillance and reoperation for high-grade stenosis was associated with a 1.6% incidence rate of disabling stroke during the follow-up period.

Duplex features of vein graft stenosis and the success of percutaneous transluminal angioplasty

PURPOSE

To determine if criteria exist that are correlated to a successful outcome after balloon angioplasty for vein graft stenosis.

METHODS

During a 5-year period, duplex surveillance of 380 infrainguinal vein bypasses identified 76 hemodynamically failing grafts (87 stenoses) requiring intervention. Percutaneous transluminal angioplasty (PTA) was selected over surgical repair based on 3 criteria: time interval from primary grafting procedure, vein graft diameter, and stenosis length. The 28 (32%) stenoses (20 grafts) treated by PTA were used in a retrospective analysis to test if any variables favored a successful outcome. Patient and lesion characteristics, graft patency, and restenosis following PTA were correlated with duplex features of the stenosis recorded prior to, immediately after, and at 3- to 6-month intervals postprocedurally.

RESULTS

Lesion characteristics that correlated with a successful outcome were vein size > or = 3.5 mm, lesion length < 2 cm, and appearance > 3 months after surgery. Conduit type, PTA site, patient demographics, and indication for bypass did not correlate with PTA durability. Nineteen lesions in 13 grafts met these criteria (group 1), while 9 stenoses in 7 grafts did not (group 2). Lesion severity based on duplex velocity measurements were similar in both groups before (p = 0.40) and after (p = 0.32) treatment. During the mean 21-month follow-up, group 1 grafts required less intervention (p = 0.035). At last follow-up, hemodynamic changes were durable in group 1 (p = 0.0068) but not in group 2 (p = 0.39).

CONCLUSIONS

Selection of vein graft stenoses for treatment by PTA can be based on temporal and duplex data. PTA of short (< 2 cm) stenoses in good caliber veins (> or = 3.5 mm) appearing > 3 months after bypass placement was durable with a late intervention rate of approximately 10%. Direct surgical repair or replacement is recommended for early (< 3 months) and/or long segment stenoses that develop in small caliber conduits.

Surgical and endovascular intervention for infrainguinal vein graft stenosis

PURPOSE

The purpose of this study was to evaluate the stenosis-free patency of open repair (vein-patch angioplasty, interposition, jump grafting) and percutaneous transluminal balloon angioplasty (PTA) of 144 vein graft stenoses that were detected during duplex scan surveillance after infrainguinal vein bypass grafting.

METHODS

Patients who underwent revision of an infrainguinal vein bypass graft were analyzed for type of vein conduit, vascular laboratory findings leading to revision, repair techniques, assisted graft patency rate, procedure mortality rate, and restenosis of the repair site.

RESULTS

The time of postoperative revision ranged from 1 day to 133 months (mean, 13 months). One hundred eighteen primary and 26 recurrent stenoses (peak systolic velocity, >300 cm/s) in 52 tibial and 35 popliteal vein bypass grafts were identified by means of duplex scanning. The repairs consisted of 77 open procedures (vein-patch angioplasty, 28; vein interposition, 33; jump graft, 9; primary repair, 3) and 67 PTAs. No patient died as a result of intervention. Cumulative assisted graft patency rate (life-table analysis) was 91% at 1 year and 80% at 3 years. At 2 years, cumulative assisted graft patency rate was comparable for saphenous vein grafts (reversed, 94%; in situ, 88%; nonreversed, 63%) and alternative vein grafts (89%). Stenosis-free patency rate at 2 years was identical (P =.55) for surgical intervention (63%) and endovascular intervention (63%) but varied with type of surgical revision (P =.04) and time of intervention (<4 months, 45%; >4 months, 71%; P =.006). The use of duplex scan-monitored PTA to treat focal stenoses (<2 cm) and late-appearing stenoses (>3 months) was associated with a stenosis-free patency rate that was 89% at 1 year. After intervention, the alternative vein bypass grafts necessitated twice the reinterventions per month of graft survival (P =.01). Bypass graft to the popliteal versus infrageniculate arteries, site of graft stenosis (vein conduit, anastomotic region), and repair of a primary versus a recurrent stenosis did not influence the outcome after intervention.

CONCLUSION

The revision of duplex scan-detected vein graft stenosis with surgical or endovascular techniques was associated with an excellent patency rate, including when intervention on alternative vein conduits or treatment of restenosis was necessary. When PTA was selected on the basis of clinical and duplex scan selection criteria, the endovascular treatment of focal vein graft stenosis was effective, durable, and comparable with the surgical revision of more extensive lesions.

Natural history of infrainguinal vein graft stenosis relative to bypass grafting technique

PURPOSE

To determine whether the incidence of vein graft stenosis is related to bypass grafting technique and thus modification of postoperative surveillance protocols may be required.

METHODS

From 1991 to 1996, 338 infrainguinal vein bypasses constructed using in situ (n = 131), reversed (n = 120), nonreversed translocated (n = 48), or spliced/upper extremity vein (n = 39) grafting techniques were evaluated by intraoperative duplex scanning to optimize bypass construction and serially thereafter to detect developing vein graft stenoses. Bypass procedures were performed in 322 patients for critical limb ischemia (83%), claudication (13%), or popliteal aneurysm (4%). Using life-table analysis, graft patency and revision/failure rates were compared relative to grafting technique, need for operative revision, and intraoperative duplex scan results.

RESULTS

Three-year primary and secondary graft patency rates were higher (p < 0.001) for in situ bypass grafts (85%/97%) compared with reversed (57%/83%), nonreversed translocated (62%/78%), or alternative (51%/76%) vein bypass grafts. During a mean follow-up interval of 19 months, the incidence of graft revision was higher for reversed saphenous (23%) and alternative (28%) vein bypass grafts compared with in situ (10%) or nonreversed (16%) saphenous vein bypass grafts. Despite a normal intraoperative graft duplex scan, the revision/failure rate of reversed vein grafts was 2.5 times greater than in situ/nonreversed translocated vein conduits (primary patency rate at 3 years, 60% vs 87%, p = 0.009). Bypass grafts modified at operation on the basis of duplex scanning were two times more likely to require postoperative revision than grafts with normal intraoperative scans.

CONCLUSIONS

The incidence of postoperative graft stenosis and need for revision varies with bypass grafting technique. Reversed vein bypasses and grafts modified at operation may be more prone than in situ vein bypass grafts to develop stenosis and thus require intensive surveillance. Infrainguinal vein graft failure and the need for revision may be reduced by the adoption of bypass grafting techniques that include valve lysis and intraoperative duplex scan assessment.

Nature and management of duplex abnormalities encountered during infrainguinal vein bypass grafting

PURPOSE

This study was undertaken to evaluate the application of duplex scanning during infrainguinal vein grafting procedures to verify vein conduit preparation, anastomotic patency, and graft hemodynamics.

METHODS

Between 1991 and 1995, 275 infrainguinal vein bypasses (in situ, 114; reversed, 82; nonreversed translocated, 48; spliced alternative/arm vein, 31) to the popliteal (n = 116) or an infrageniculate artery (n = 159) were scanned during surgery for sites of color Doppler flow abnormality. Duplex-detected defects were graded with peak systolic velocity and velocity ratio criteria. Sites that demonstrated highly disturbed flow (peak systolic velocity > 180 cm/sec, velocity ratio > 2.4) were immediately revised by direct repair, patch angioplasty, or interposition grafting.

RESULTS

Intraoperative duplex scanning prompted revision of 50 abnormalities in 43 of the 275 grafts (16%), including 32 vein and seven anastomotic stenoses, nine vein segments with platelet thrombus, and two bypasses with low flow. The intraoperative revision rate was lowest (p < 0.02) for reversed saphenous vein bypasses (7%) compared with other grafting techniques (in situ, 20%; nonreversed translocated, 15%; spliced alternative vein, 23%). The revision rates of popliteal and tibial bypasses were similar (14% vs 17%). A normal result shown by intraoperative scan (235 bypasses) was associated with a low 90-day thrombosis (0.4%) and revision (2%) rate, whereas six of 15 grafts (40%) with residual and 13 of 25 grafts (52%) with unrepaired duplex abnormalities required corrective procedures (p < 0.001). One graft failed within 3 months (secondary patency rate, 99%).

CONCLUSIONS

Intraoperative duplex scanning accurately predicted the technical adequacy of infrainguinal vein grafts and was particularly useful in assessing bypasses constructed with valve lysis techniques or alternative veins. Early graft revisions indicated by duplex monitoring for thrombosis or stenosis were the result of a progression of residual defects and platelet thrombus formation rather than inadequate graft run-off flow.

Secondary recurrent carotid stenosis

PURPOSE

Recurrent carotid stenosis after carotid endarterectomy has been extensively reported. The occurrence, however, of another ipsilateral restenosis that requires a third carotid operation is rare. The purpose of this study was to evaluate possible risk factors and the most efficacious management of the patient with "secondary" recurrent carotid stenosis.

METHODS

A survey of the Southern Association for Vascular Surgery was performed, and 31 patients who had had surgery for secondary recurrent carotid stenosis were identified.

RESULTS

The mean interval between the recurrent stenosis operation and secondary recurrent carotid stenosis was 39.8 months (range, 9 to 83 months). At the third operation, 21 patients underwent carotid patch angioplasty and 10 underwent carotid resection with an interposition saphenous vein graft. No postoperative strokes or deaths occurred; three patients (10%) had a peripheral nerve injury. Nine early (< 24 mo) secondary recurrent carotid stenoses occurred, and these patients underwent patch angioplasty. Twenty-three female, cigarette-smoking patients and 20 patients with elevated lipid levels had early restenosis and were identified as being at high risk for the development of another stenosis. A fourth significant stenosis developed in five of these high-risk patients who had saphenous vein patch angioplasty at their third carotid operation; eight other high-risk patients had carotid resection with an interposition saphenous vein graft, and no other stenosis developed.

CONCLUSION

Patients who have secondary recurrent carotid stenoses can safely undergo a third carotid operation. Female habitual smokers with elevated lipid levels and an early restenosis appear to be at high risk of secondary recurrent carotid stenoses. When surgery is necessary, carotid resection with an interposition saphenous vein graft appears more durable than patch angioplasty.

In situ repair of mycotic abdominal aortic aneurysms with rifampin-bonded gelatin-impregnated Dacron grafts: a preliminary case report

Treatment of mycotic aortic aneurysm by excision and extraanatomic bypass is difficult to apply when the infectious process involves the visceral arteries. On the basis of experimental studies in our laboratory that demonstrated prolonged antistaphylococcal activity of rifampin-bonded, gelatin-impregnated Dacron grafts after implantation in the arterial circulation, this conduit was successfully used for in situ replacement of a native aortic infection in two patients. Both patients had fever, leukocytosis, abdominal or back pain, and a computed tomographic scan that demonstrated contained rupture of a mycotic aneurysm. Preoperative computed tomography-guided aspiration and culture of periaortic fluid from one patient grew Staphylococcus aureus. Treatment consisted of prolonged (6 weeks) culture-specific parenteral antibiotic therapy, excision of involved aorta, oxychlorosene irrigation of the aortic bed, and restoration of aortic continuity by in situ prosthetic replacement. A preliminary right axillobifemoral bypass was performed in the patient who had an infection involving the suprarenal and infrarenal aorta. In both patients intraoperative culture of aorta wall recovered S. aureus. Patients were discharged at 20 and 21 days. Clinical follow-up and computed tomographic imaging of the replacement graft beyond 10 months after surgery demonstrated no signs of residual aortic infection. In the absence of gross pus and frank sepsis, the use of an antibiotic-bonded prosthetic graft with antistaphylococcal activity should be considered in patients who have arterial infections caused by S. aureus when excision and ex situ bypass are not feasible.

Anatomic patterns of carotid endarterectomy healing

BACKGROUND

Restenosis after carotid endarterectomy is a dynamic process likely influenced by surgical technique as well as by anatomic, hemodynamic, and patient factors.

METHODS

To characterize the healing of carotid endarterectomy sites, intraoperative and serial postoperative color duplex scans were performed in 126 patients (136 repairs). Vessel-wall imaging, midstream spectral analysis, and measurements of diameter and cross-sectional area from common carotid artery (CCA) and internal carotid artery (ICA) segments were compared (at 3, 6, 15, and 30 months) and severity of lumen stenosis was determined.

RESULTS

After primary closure (n = 15), patch angioplasty (n = 121), or intraoperative revision based on duplex scanning (n = 5), 12 repairs had mild residual flow abnormalities and 1 repair had a moderate flow abnormality. Mean ICA bulb diameter was greater in patched repairs (0.81 cm, range 0.6 to 1.1 cm) than primary closed repairs (0.7 cm, range 0.45 to 0.8 cm). No ICA occluded during follow-up (mean 24 months), and three repairs, two in the ICA and one in the CCA, demonstrated 50% to 75% diameter reduction at 9 months. Lumen cross-sectional area of vein-patched repairs increased 0.6 cm2 to 0.76 cm2 (P < 0.01) in the ICA and 0.69 cm2 to 1.1 cm2 (P < 0.01) in the CCA segments by 3 months compared with intraoperative measurement. Four patients with progressive dilatation of the patch segment to a mean of 1.77 cm2 developed asymptomatic posterior wall mural thrombus. Postoperative blood flow velocities measured through the repair were similar to intraoperative values. Minor intraoperative hemodynamic abnormalities were not associated with the development of restenosis, and changes in repair site anatomy occurred within 3 months with little change thereafter.

CONCLUSIONS

We have found intraoperative scanning useful for detection of anatomic defects and associated turbulence, lesions that should be immediately corrected. Surgical technique that achieves normal intraoperative carotid flow hemodynamics and B-mode ultrasonic vessel wall appearance should predict an endarterectomized segment free of significant residual plaques and neointimal hyperplasia. Tailoring of the vein patches to achieve lumen diameters < 1 cm is recommended because of the dilataton likely to develop after surgery that may lead to vessel wall mural thrombus.

Vascular injury associated with extremity trauma

Limb salvage in patients with combined orthopaedic and vascular injuries is highly dependent on the severity of injury and the expeditious diagnosis and treatment of vascular trauma. Diagnostic arteriography should be used selectively to identify an occult injury in patients with an abnormal physical examination or to establish the anatomy and precise location of injury. Measurement of limb pressures using a Doppler device and use of duplex ultrasonography are valuable adjuncts in the rapid evaluation of patients with trauma for arterial injury. When unequivocal evidence of arterial injury is present and the operative approach is established easily by the mechanism and site of injury, treatment should not be delayed by confirmatory arteriography. Vascular repair should precede orthopaedic stabilization particularly if critical ischemia is present. Amputation rates after extremity trauma continue to decrease because of rapid patient transport (decrease in warm ischemia time) and a team approach to injury repair. Technical success of restoring arterial patency and limb perfusion is achieved in > 95% of patients. Early amputation is related to prolonged ischemia and soft tissue injury that precludes a viable, functional extremity. Late amputation is done for disability, a useless, painful limb, or chronic infection.

Failure of foot salvage in patients with end-stage renal disease after surgical revascularization

PURPOSE

This report ascertained factors responsible for for failure of foot salvage in patients with end-stage renal disease (ESRD) after undergoing infrainguinal bypass for critical ischemia.

METHODS

A retrospective review of 69 distal arterial reconstructions performed in 53 patients with ESRD (hemodialysis [n = 37], kidney transplantation [n = 10], peritoneal dialysis [n = 6]) for foot gangrene (n = 28), nonhealing ulcer (n = 25), or ischemic rest pain (n = 16) was conducted. Endpoints of surgical morbidity, limb loss, and graft patency were correlated with extent of preoperative tissue loss and presence of diabetes mellitus.

RESULTS

The 30-day operative mortality rate was 10%, and the patient survival rate at 2 years was 38%. The primary graft patency rate was 96% at 30 days, 72% at 1 year, and 68% at 2 years. Eleven of 22 foot amputations performed during the mean follow-up period of 14 months (range 3 to 96 months) occurred within 2 months of revascularization. Mechanisms responsible for limb loss included graft failure (n = 9), foot ischemia despite a patent bypass (n = 8), and uncontrolled infection (n = 5). Overall, 59% of amputations were performed in limbs with a patent bypass to popliteal or tibial arteries. Healing of forefoot amputations was prolonged, but all limb loss beyond 9 months of revascularization was due to graft failure. The limb salvage rate at 1 year decreased (p = 0.13) from 74% to 51% in patients admitted with gangrene. Only two of seven patients admitted with forefoot gangrene experienced foot salvage.

CONCLUSION

Failure of foot salvage in patients with ESRD and critical ischemia was due to wound healing problems rather than graft thrombosis. Earlier referral for revascularization, before development of extensive tissue ischemia and infection, is recommended. Primary amputation should be considered in patients admitted with forefoot gangrene, particularly if it is complicated by infection.

Antistaphylococcal activity of rifampin-bonded gelatin-impregnated Dacron grafts

The affinity of rifampin to bond to Dacron permits implantation of a vascular prosthesis with anti-staphylococcal bioactivity. The performance of rifampin-bonded Dacron grafts was evaluated in vitro and in vivo to develop a bonding technique with optimal graft bioactivity which was then used for in situ reconstruction of a biofilm graft infection. In vitro bioactivity was measured at 24-hr intervals for three types of Dacron prostheses (plain, gelatin, and collagen-impregnated) exposed to rifampin at varied concentrations and immersion times. Gelatin-impregnated grafts demonstrated superior bioactivity (P < 0.05). Rifampin concentration and graft type had a greater effect on bioactivity than immersion time (P < 0.01). Gelatin-impregnated grafts immersed in a 60 mg/ml rifampin solution for 15 min produced optimum bioactivity. Six grafts prepared in this fashion were used to replace the canine aorta. The level and duration of in vivo antistaphylococcal activity to Staphylococcus aureus and Staphylococcus epidermidis were less (P < 0.05) than those measured in vitro, but rifampin levels exceeded the study strain maximum inhibitory concentration for up to 48 hr. In a canine model, the rifampin-bonded gelatin-impregnated (N = 14) or nonbonded control (N = 10) grafts were used as in situ replacement for an established aortic graft infection caused by S. epidermidis. Replacement with a rifampin-bonded graft resulted in successful anatomic healing of perigraft and anastomotic tissue. Persistent biofilm colonization was confirmed in 8 of 10 controls versus 4 of 14 rifampin-bonded grafts (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

The origin of infrainguinal vein graft stenosis: a prospective study based on duplex surveillance

PURPOSE

The purpose of this study was to determine the origin of vein graft lesions and their propensity for progression based on prospective duplex surveillance of 135 infrainguinal vein bypasses.

METHODS

One hundred sixteen greater saphenous, 13 spliced, five cephalic, and one superficial femoral vein grafts were evaluated by color duplex imaging at surgical procedure, 1 and 6 weeks, 3 and 6 months, and every 3 to 6 months thereafter. Duplex-identified lesions were graded by peak systolic velocity and velocity ratio criteria and were either followed or subjected to revision.

RESULTS

Early postoperative duplex surveillance allowed stratification of infrainguinal grafts into two subsets. Of 91 (67%) grafts with normal early scans (at 3 months), only two (2.2%) developed de novo stenoses (at 6 and 8 months) that required revision. Forty-four grafts with abnormal duplex scans had a focal flow abnormality (peak systolic velocity > 150 cm/sec, velocity ratio > 1.5) in the graft body (n = 24) or anastomotic region (n = 20). In 14 grafts the flow abnormality (mean peak systolic velocity = 217 cm/sec, velocity ratio = 2.3) normalized. Ten additional grafts exhibited a moderate, persistent graft stenosis (mean peak systolic velocity 248 cm/sec, velocity ratio = 3.3) that was not repaired. All 20 grafts with lesions that progressed to high-grade stenosis (mean peak systolic velocity = 362 cm/sec, velocity ratio = 7.2) and were revised had a residual flow abnormality confirmed at operation, or it appeared by 6 weeks. In the entire series six (4.4%) grafts failed during the mean 12-month follow-up interval (range 3 to 30 months), 4 with unrepaired defects and two after revision.

CONCLUSIONS

Prospective duplex surveillance verified that de novo graft stenosis was uncommon (< 2.2%) after reversed and in situ saphenous vein bypass grafting. Graft stenoses developed at sites of unrepaired defects or early appearing conduit abnormalities. An early appearing duplex focal flow abnormality warranted careful surveillance, because one half of such sites progressed to a high-grade stenosis. Grafts with normal early duplex scans exhibited a low incidence of stenosis development or occlusion, and thus less intense postoperative surveillance can be recommended.

The utility and durability of vein bypass grafts originating from the popliteal artery for limb salvage

BACKGROUND

Short vein grafts originating from sites distal to the common femoral artery have been reported to be useful in selected patients with tibial artery disease. From 1987 to 1993, we performed 504 consecutive infrainguinal vein bypass grafts, of which 56 (11%) originated from the popliteal artery, 25 above and 31 below the knee.

PATIENTS AND METHODS

The patients were 16 women and 37 men, with a mean age of 62.4 years. Eighty-seven percent were diabetic, 57% had clinically obvious coronary artery disease, and 28% had end-stage renal disease (ESRD). The indication for surgery was ulceration or gangrene in 93% of cases. We preferentially used reversed greater saphenous vein harvested from the thigh to optimize conduit quality and avoid lower leg wound complications. The outflow artery sites were: dorsal pedal (17), posterior tibial (14), peroneal (10), anterior tibial (8), lateral or medial plantar (5), and sequential tibial (2). All patients were followed postoperatively with serial duplex surveillance. The mean follow-up was 12.5 months (range 1 to 66).

RESULTS

In-hospital mortality was 5.4%. Mortality at 24 months was 19% overall and 38% in patients with ESRD. Limb salvage was 77% at 3 years, 92% in patients with normal renal function versus 59% in those with ESRD (P < 0.003). Primary graft patency by life-table analysis was 94% at 1 month and 84% at 3 years. Five patients with patent grafts required amputation, 4 early and 1 late. Eight months after surgery, 1 patient (1.8%) developed superficial femoral artery stenosis which was diagnosed by duplex surveillance and successfully treated by percutaneous transluminal balloon angioplasty.

CONCLUSIONS

Vein bypass grafts originating from the popliteal artery are effective and durable. Proximal disease progression rarely poses a significant threat to long-term graft patency. Patients with ESRD, blind tibial outflow tracts, and extensive forefoot lesions appear to be at increased risk of limb loss even with continued graft patency.

Intraoperative duplex scanning of arterial reconstructions: fate of repaired and unrepaired defects

PURPOSE

Because unrecognized lesions can cause an arterial reconstruction to fail, duplex ultrasonography was evaluated as an intraoperative aid to assess technical adequacy and provide criteria for which lesions should be repaired immediately versus safely followed.

METHODS

Since 1990 intraoperative color duplex scanning(7 to 10 MHz linear array probe, pulsed-wave Doppler test spectrum analysis) was used to assess the frequency and severity of residual lesions in 368 patients after carotid endarterectomy (n = 210), infrainguinal vein bypass (n=135) or visceral/renal reconstruction (n = 23). Duplex scan results were categorized as normal or abnormal, with immediate repair of lesions demonstrating both lumen reduction and severe focal flow abnormalities (peak systolic velocity [Vp] > 150 to 180 cm/sec;velocity ratio [Vr] > 2.4). Arteriography was also performed in 81% of lower limb bypass procedures.

RESULTS

Duplex scanning identified technical (residual plaque, stricture) or intrinsic defects (platelet thrombus, distal thrombosis) requiring revision in 37 (10%) of the reconstructions. Infrainguinal bypass had the highest incidence of corrected defects (14%) and adverse events (3%). No adverse events occurred in patients with normal duplex scan results or after carotid endarterectomy. Overall, 76% of identified defects were corrected (carotid, 17 of 24; infrainguinal bypass, 19 of 24; visceral bypass, 1 of 1). Unrepaired flow defects (Vp = 150 to 190 cm/sec; Vr = 1.8 to 2.5) led to one graft occlusion and three early revisions. Postoperative duplex scanning demonstrated residual stenosis in seven of 12 patients with unrepaired defects, two of 36 patients with repaired defects, and five of 312 patients with normal scan results (p < 0.001).

CONCLUSION

Based on the types of lesions corrected and the low (< 0.5%) complication rate after a normal or modified arterial reconstruction, duplex scanning was found to be a valuable intraoperative aid. Unrepaired defects require close surveillance for progression.

Prosthetic graft infection

This article outlines the tenets and basic data critical for the management of prosthetic graft infections. Diagnostic algorithms and treatment options appropriate for patients with symptoms and signs suggestive of graft infection are presented.

Does arterial inflow failure cause distal vein graft thrombosis? A prospective analysis of 450 infrainguinal vascular reconstructions

Classically, inadequate arterial inflow, diseased runoff, and poor bypass conduit quality have all been cited as causes of infrainguinal vein graft failure. To examine the role of arterial inflow failure as a specific cause of vein graft thrombosis, we prospectively analyzed 450 consecutive infrainguinal vascular reconstructions by means of a strict duplex scan surveillance protocol at three teaching institutions from 1986 to 1993. Sixteen incidences of arterial inflow failure (11 occlusions and five high-grade stenoses) above previously placed infrainguinal vein grafts were identified in 14 patients and confirmed by arteriography. Despite these inflow failures, all 14 autogenous vein infrainguinal reconstructions remained patent on arteriography. These inflow failures were observed from 2 to 72 months (mean 16 months) after infrainguinal reconstruction. Immediate successful inflow repair was performed in 13 of the 16 failures. Conversely, among 450 grafts followed, 37 acute graft occlusions occurred-all with arteriographically or noninvasively documented normal inflow. Thus no graft in the series has yet failed as a result of inflow occlusion (mean follow-up 22 months; range 1 to 78 months). We thus conclude that properly constructed infrainguinal saphenous vein bypass grafts with an intact endothelium often remain patent through low-flow collateral vessels despite total arterial inflow occlusion. These data thus challenge the premise that arterial inflow disease is a major cause of infrainguinal vein bypass occlusion.

Treatment of bacteria-biofilm graft infection by in situ replacement in normal and immune-deficient states

PURPOSE

Complications of grafts infected with coagulase-negative staphylococci can be eradicated by antibiotic administration, tissue debridement, and in situ graft replacement, but successful treatment may be diminished in a setting of altered immune function.

METHODS

In a canine model of an established aortic graft infection from Staphylococcus epidermidis, outcomes after in situ replacement were compared between normal dogs and animals made immune-deficient by administration of azathioprine (50 mg/day) and prednisone (10 mg/day). In situ replacement of an infected infrarenal aortic graft with either antibiotic-bonded (silver-ciprofloxacin: Ag-cipro) or conventional polytetrafluoroethylene (PTFE) grafts was performed in 17 control and 18 immune-deficient animals.

RESULTS

Four weeks after implantation of a Dacron graft colonized with a biofilm of S. epidermidis, all study animals demonstrated a bacterial biofilm infection with perigraft inflammation or abscess, and in immune-suppressed dogs the incidence of perianastomotic aortitis was increased (p < 0.05). Six weeks after in situ replacement both the Ag-cipro and conventional PTFE grafts were healed without signs of infection in controls, but anatomic evidence of persistent infection and increased S. epidermidis recovery was observed in immune-suppressed animals that underwent in situ replacement of a standard (five of seven) versus antibiotic-bonded (one of 11) PTFE graft (p < 0.006). Overall in situ replacement with an antibiotic-bonded graft yielded a lower frequency of S. epidermidis recovery (two of 19 Ag-cipro graft biofilm with positive culture results versus nine of 16 conventional graft biofilm with positive culture results; (p < 0.003).

CONCLUSIONS

This study supports the efficacy of in situ replacement for low-grade graft infections caused by S. epidermidis in normal hosts and demonstrates superiority of antibiotic-bonded grafts in immune-deficient hosts.

Intraoperative thrombolysis in peripheral arterial occlusion

Thromboembolic occlusion of peripheral arteries continues to be associated with significant morbidity, mortality and loss of limbs. Surgical intervention with prompt revascularization by clot extraction, alone or in combination with arterial bypass, remains the standard therapy for critical ischemia with imminent tissue loss. Mechanical thrombectomy using a balloon catheter has been the preferred technique for distal embolus or thrombus extraction. Unfortunately, complete thrombectomy is rare, and the procedure is associated with arterial wall injury. Intraoperative thrombolytic therapy is an attractive adjunct to catheter thrombectomy alone and is appropriate in the care of a significant number of patients with acute limb ischemia. Its safety and efficacy have been confirmed in the laboratory and in a limited number of patients. The authors review experimental and clinical data and report their experience with 19 patients.

Thrombolysis in peripheral arterial graft occlusion

Acute thrombosis of arterial bypass grafts in the lower extremities poses a significant risk for limb loss. Graft salvage in patients affected by this complication remains a challenge. The vascular surgeon must consider the spectrum of treatment options (thrombolysis, thrombectomy, graft replacement) in managing acute graft thrombosis. Oral anticoagulants should be considered in patients with low-flow polytetrafluoroethylene (PTFE) grafts and after successful thrombolysis, with or without revision. The role of thrombolytic therapy for occluded vein grafts is less clear, but successful lysis is likely in patients who present within 48 hours of graft thrombosis and the etiology includes a correctable graft stenosis.

Symptomatic recurrent carotid stenosis and aneurysmal degeneration after endarterectomy

BACKGROUND

Aneurysmal degeneration of a carotid reconstruction was not recognized until the patient, who was known to have recurrent carotid artery stenosis, had a thromboembolic stroke. This sequelae of carotid endarterectomy is a serious complication, associated with a high morbidity and mortality rate. This review was conducted to establish the risk of transient ischemic attack and stroke for patients found to have recurrent carotid stenosis associated with aneurysmal degeneration of the carotid artery after endarterectomy.

METHODS

A case is reported, and 100 literature references of aneurysmal degeneration of the carotid artery after endarterectomy were reviewed.

RESULTS

False aneurysm from anastomotic disruption was the most common presentation identified in the cases reviewed. Nineteen of the patients had a significant neurologic event; however, three (50%) of six patients with aneurysm and recurrent carotid artery stenosis had a transient ischemic attack or stroke.

CONCLUSIONS

The incidence of neurologic symptoms is markedly increased when recurrent carotid artery stenosis is associated with carotid aneurysm. During postoperative surveillance after endarterectomy, the identification of recurrent carotid artery stenosis requires evaluation for aneurysmal degeneration of the carotid artery with duplex scanning. These patients are at significant risk for transient ischemic attack and stroke. This rare complication merits operative repair.

The importance of intraoperative detection of residual flow abnormalities after carotid artery endarterectomy

PURPOSE

The efficacy of carotid endarterectomy in the prevention of strokes mandates low perioperative morbidity, as well as a low incidence of late ipsilateral stroke. This prospective study involving 430 patients (461 carotid endarterectomies) correlated the results of intraoperative assessment with end points of stroke and residual/recurrent internal carotid artery (ICA) stenosis.

METHODS

Adequacy of the repair was assessed by ultrasound studies (duplex scan and pulsed Doppler spectral analysis) alone (n = 142), ultrasound studies and arteriography (n = 268), or clinical inspection (n = 51). After operation, duplex ultrasonography was used to confirm patency and categorize severity of ICA stenosis. At operation 26 carotid endarterectomy sites (5.6%), were revised based on intraoperative studies.

RESULTS

Perioperative (30-day) morbidity rates were similar in patients with normal, mildly abnormal, or no ultrasound completion studies. There were six permanent (1.3%) and 12 temporary (2.6%) neurologic deficits and six deaths, including four fatal strokes and two fatal myocardial infarctions. By life-table analysis, the incidence of greater than 50% diameter-reducing ICA stenosis or occlusion was increased (p < 0.007, log-rank test) in patients with residual flow abnormality or no study. More important, patients with normal intraoperative flow studies had a significantly lower rate of late ipsilateral stroke compared with the remaining patient cohort (p = 0.04, log-rank test). During the mean 30-month follow-up interval, the incidence of late stroke was increased (p = 0.00016) in patients with ICA restenosis or occlusion (3/35) compared with patients without recurrent stenosis (3/426).

CONCLUSION

Confirmation of a normal repair at operation affords the best opportunity to minimize ischemic neurologic events and anatomic restenosis after carotid endarterectomy.

Durability of the in situ bypass following modification of abnormal vein segment

Modification procedures performed during in situ bypass grafting to correct an injured or inadequate saphenous vein segment result in a significant increase in the incidence of vein graft complications in the follow-up period. Modification procedures were performed in 96 in situ saphenous vein bypasses and consisted of primary closure (n = 28), vein patch angioplasty (n = 31), or resection and/or replacement (n = 37). At 4 years primary patency was 54%, secondary patency was 73%, and limb salvage was 89%. The incidence of subsequent vein graft stenosis and revision or graft failure was similar for grafts requiring vein patch angioplasty (7 of 31, 23%), primary repair (9 of 28, 32%), and resection and/or replacement (16 of 37, 43%) (p not equal to ns). Only 4 bypass revisions were performed for stenosis at the site of the original modification procedure. The type of vein graft repair did not significantly affect the primary patency at 18 months (primary closure, 65%, vein patch angioplasty, 66%, and resection and/or replacement, 58%) or the secondary patency at 30 months (primary closure, 80%, vein patch angioplasty, 90%, and resection and/or replacement, 77%). Modified autogenous conduits maintain patency and limb salvage but are prone to develop graft complications in the follow-up period.

Perioperative Coagulation Changes with Gastric Bypass: association with venous thrombosis?

Blood coagulation protein analyses were obtained before, during and after Roux-Y gastric bypass in 82 patients to observe the individual perioperative changes indicative of clot formation and fibrinolysis. Pneumatic compression devices were placed on the legs during this time in order to provide deep venous thrombosis (DVT) prophylaxis, and non-invasive venous thrombosis detection studies were performed before and after operation. No occasions of DVT or pulmonary emboli were detected postoperatively. Preoperative balanced ratios of antithrombin III/plasminogen were maintained intraoperatively and were increased postoperatively, reflecting on-going fibrinolysis. Changes in alpha-2 antiplasmin confirmed this interpretation. Patients subdivided into super- vs morbid obese groups showed less plasminogen reduction and a lower protein ratio during and after operation, and less antiplasmin consumption intraoperatively, in the heavier group. A linear regression analysis of excess weight on the protein ratio also showed lower ratios in the heavier patients. However, calf or thigh leg circumferences were not different between super- and morbid obese patients. These results suggest that leg pneumatic compression should be as effective but the immobility of super-obese patients may contribute to perioperative hypofibrinolysis and perhaps make them more susceptible to DVT and pulmonary embolism.

Determinants of successful peroneal artery bypass

PURPOSE

The purpose of this study was to identify the determinants of long-term success with the peroneal artery bypass.

METHODS

Seventy-seven consecutive peroneal artery bypasses performed between 1981 and 1990 were reviewed to evaluate the influence of venous conduit modification, surgeon experience, patency of the dorsalis pedis or posterior tibial artery at the ankle, and the quality of the peroneal collateral branches and pedal arch. The average follow-up was 34 months (range 1 to 92 months).

RESULTS

The 5-year primary and secondary patency rates were 61% and 92%, respectively. Modification of the vein graft at the initial procedure was necessary in 26 (34%). This led to a reduced (p < 0.001) 5-year primary patency rate of 22% compared with 80% for unmodified conduits. Operative results improved with surgeon experience. The 5-year secondary patency rate of grafts placed before 1985 was 82% compared with 98% for subsequent grafts (p < 0.03). The initial postoperative mean ankle/brachial index for grafts revised for hemodynamic failure or thrombosis in the follow-up period was 0.84 compared with 0.95 in grafts that did not require revision (p < 0.04). The presence of a patent dorsalis pedis or posterior tibial artery at the ankle and an intact pedal arch did not significantly influence primary or secondary patency. The 5-year secondary graft patency rate for patients with a patent dorsalis pedis or posterior tibial artery at the ankle was 88%.

CONCLUSIONS

The peroneal artery should be selected for outflow when it is the single tibial runoff vessel and is preferable to a bypass to an inframalleolar arterial segment. The quality of the venous conduit and the technical skill of the surgeon are the two most important factors in the success of bypasses to the peroneal artery.

Biologic characteristics of long-term autogenous vein grafts: a dynamic evolution

PURPOSE

The venous conduit as an arterial substitute has dynamic biologic properties that affect its durability. This study evaluated the morphologic and physiologic characteristics of 72 lower extremity vein grafts functioning at 4.5 to 21.6 years (median 6.6 years).

METHODS

The entire graft was imaged with use of color duplex ultrasonography and then classified as normal (class I), abnormal but not graft-threatening (class II), or abnormal and graft-threatening (class III) for the proximal, middle, and distal thirds. Thirty-one grafts (43%) were classified as normal, whereas 41 (57%) were classified as abnormal, with 58 class II and 15 class III segments.

RESULTS

Three types of abnormalities were found by duplex imaging: nonstenotic wall plaques, discrete stenoses, and aneurysmal dilation. Aneurysms developed in five of seven grafts that had required thrombectomy in the distant past (mean of 40 months). There were 70 postoperative revisions in 38 limbs (53%). In 23 (60%) the conduit was revised, in 11 (29%) the revisions corrected progression of native artery atherosclerotic disease, and in 4 (11%) both types of revisions were required. Eleven grafts were revised in the first 30 days to correct technical errors. Eighteen limbs were revised between 1 and 24 months, with 12 (67%) of the revisions correcting stenotic lesions in the conduit or at one of the anastomoses. After 24 months 12 (67%) of 18 limbs were revised to correct progression of occlusive disease in the inflow or outflow vessels. At the time of this study 18 (67%) of the 27 conduits revised for intrinsic lesions were abnormal by color duplex imaging, and they harbored 12 (80%) of the 15-graft-threatening lesions.

CONCLUSIONS

Autogenous vein remains the most durable arterial conduit, but vigilant surveillance is essential because the atherosclerotic environment continually produces lesions that may imperil the longevity of the graft.

Noninvasive vascular laboratory in clinical practice

Noninvasive vascular testing methods have validated application in the evaluation of patients with suspected peripheral arterial, cerebrovascular, or peripheral venous disease. Accurate and reproducible testing requires the use of appropriate instrumentation by experienced technologists, and interpretation of data with verified diagnostic criteria. Noninvasive testing can facilitate clinical decision-making by providing quantitative anatomical and hemodynamic data, thereby quantifying functional severity of disease. Duplex ultrasonography is essential instrumentation for cerebrovascular testing to localize and grade occlusive lesions. In peripheral arterial testing, the combination of segmental pressure measurements and waveform (velocity, pulse pressure) analysis should be the initial diagnostic method, with duplex scanning reserved for characterizing hemodynamically abnormal arterial segments. A number of techniques (duplex scanning, B-mode imaging supplemented by Doppler, venous outflow plethysmography) are appropriate for assessing the venous system for thrombosis, structural abnormalities, and venous valve function. Physicians should be aware of the pitfalls of noninvasive vascular testing and confirm equivocal studies using "gold standard" diagnostic methods such as arteriography and contrast venography.

Diagnosis and treatment of biomaterial-associated vascular infections

Management of biomaterial-associated vascular infections requires an understanding of pathogenetic mechanisms, risk factors, and microbiologic characteristics. Staphylococci sp., especially slime-producing strains of S. epidermidis are the prevalent pathogens. Experimental and clinical studies have indicated in situ replacement, particularly with an antibiotic-bonded prosthesis, as effective treatment for infections caused by coagulase-negative staphylococci. When sepsis is a presenting sign, prompt intervention, total excision of the prosthesis, and antibiotic administration are required.

The role of duplex scanning versus angiography in predicting outcome after balloon angioplasty in the femoropopliteal artery

Duplex-derived velocity measurements were used to assess the hemodynamics of 64 femoropopliteal arterial sites in 59 patients after angiographically successful percutaneous transluminal balloon angioplasty. With use of angiography as the gold standard, percutaneous transluminal balloon angioplasty was judged to be successful if (1) evidence existed of a "split" caused by intimal dissection and splitting of atherosclerotic plaque; and (2) no significant diameter-reducing residual stenosis was observed at the percutaneous transluminal balloon angioplasty site. At 1 month, 55 limbs (86%) were hemodynamically and clinically improved by SVS/ISCVS clinical criteria for chronic limb ischemia. Of the 55 percutaneous transluminal balloon angioplasty sites, duplex scanning had identified 40 (63%) sites with a less than 50% diameter-reducing stenosis and 15 (27%) sites with a greater than 50% diameter-reducing stenosis within a week after percutaneous transluminal balloon angioplasty. Independent review of the 55 angiograms taken after percutaneous transluminal balloon angioplasty identified 39 sites (71%) with a split and 16 sites (29%) without. By life-table analysis, a greater than 50% diameter-reducing stenosis predicted a worse clinical outcome (15% at 1 year) compared with the presence of a less than 50% diameter-reducing stenosis (84% at 1 year) (p less than 0.001; log rank test). The presence or absence of an angiographic split was not a predictive factor of percutaneous transluminal balloon angioplasty outcome (split, 61% at 1 year; no split, 62% at 1 year) (p = 0.832; log rank test). The detection of a functional residual stenosis by duplex scanning did not correlate with angiographic appearance, but was predictive of clinical failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of stress thallium imaging to stratify cardiac risk in patients undergoing vascular surgery

Reduction of the cardiac morbidity associated with major vascular procedures requires identification of high risk patients prior to operation. This retrospective study reviews the records of 126 consecutive patients who underwent 141 major vascular procedures to determine the accuracy of preoperative clinical, laboratory (ECG), and cardiac function testing (stress thallium-201 scintigraphy, left ventricular ejection fraction scan) in predicting perioperative cardiac complications. An abnormality on oral dipyridamole or treadmill thallium imaging was demonstrated prior to 71 (61%) of 116 procedures and included 20 fixed and 51 reperfusion (reversible) defects. No patient died within 30 days of operation, but 11 minor (ventricular arrhythmia) and 15 major (myocardial infarction, ischemic congestive heart failure) cardiac complications occurred. A reperfusion defect on stress thallium imaging accurately (94% sensitivity, 56% specificity, 98% negative predictive value) identified high-risk patients while accepted clinical rating systems (Goldman, Cooperman, Eagle) and preoperative level of left ventricular ejection fraction were less predictive of adverse cardiac events. Patients without myocardium at risk by coronary angiography, but a reperfusion defect on stress thallium imaging were found to be at high risk for a cardiac complication. The study data support the use of stress thallium imaging to stratify cardiac risk prior to major arterial surgery.

Comparison of serum and tissue antibiotic levels in diabetes-related foot infections

Parenteral antibiotics are used as an adjunct to amputation or operative debridement for patients with diabetes who require emergency surgery for a septic foot. In 26 patients with a diabetes-related foot infection, one dose of various intravenous antibiotic regimens (gentamicin and clindamycin, ticarcillin/clavulanate, ampicillin/sulbactam) was administered during the hour before the procedure, and assays were performed to measure the antibiotic serum and tissue levels at the time of surgical debridement. Aerobic and anaerobic cultures were performed on infected tissue. The 172 bacterial isolates, including 95 aerobes and 77 anaerobes, (6.6 isolates per patient) underwent antibiotic susceptibility testing. Antibiotic levels were calculated by biologic assay from serum and tissue biopsies from the viable margins of the surgical site, which subsequently healed primarily or supported a split-thickness skin graft. Sixteen of the patients achieved therapeutic serum levels, and therapeutic tissue levels were reached in six patients at the time of surgery. A significantly lower number of patients had therapeutic tissue levels compared to serum levels (p less than 0.01, chi square). Initial intravenous antibiotic administration provides inadequate tissue concentrations for treating foot infections in patients with diabetes. Adequate serum antibiotic levels do not reflect therapeutic tissue antibiotic levels at the surgical margins in this group of patients.

Monitoring functional patency of percutaneous transluminal angioplasty

Duplex scanning and Doppler-derived blood pressure measurements were used to serially monitor lower limb hemodynamics in 73 patients who underwent percutaneous transluminal angioplasty. Ninety percutaneous transluminal angioplasty sites judged technically satisfactory by arteriography were evaluated. Significant hemodynamic improvement was seen in 81 (90%) of the 90 limbs, although both hemodynamic and clinical improvement were achieved in only 77 (86%) limbs. Duplex scanning within 1 week of successful angioplasty identified moderate (20% to 49% diameter reduction) or severe (greater than 50% diameter reduction) residual stenosis in 49 (63%) of 77 balloon-dilated arterial segments. The presence of a greater than 50% diameter reduction residual stenosis predicted further restenosis and late clinical failure (11% success rate at 1 year). When the degree of residual stenosis at the percutaneous transluminal angioplasty site was less than 50% diameter reduction by duplex scanning, the procedure was durable (80% success rate at 2 years), even in patients with critical ischemia, poor runoff, or diabetes mellitus.