Endoluminal intervention for limb salvage after failed lower extremity bypass graft
Article Outline
Background
Lower extremity bypass graft failure in patients with limb-threatening ischemia carries an amputation rate of greater than 50%. Redo bypass is often difficult due to the lack of conduit, adequate target, or increased surgical risk, and resultant limb salvage rates are reduced significantly compared with the index operation. We set forth to investigate whether endovascular treatment in this setting would result in an acceptable limb salvage rate.
Methods
A single-institution, retrospective review from June 2004 to December 2007 of patients with failed grafts who underwent endovascular treatment with percutaneous balloon angioplasty (PTA) of their native circulation was performed. Stents were selectively used in cases of post-PTA residual stenosis or flow-limiting dissection. Technical success was defined as a residual stenosis less than 30%. Percutaneous attempts at bypass graft salvage were excluded. Demographics, comorbidities, procedural data, and follow-up information were recorded. Descriptive, logistic regression and life-table analyses were performed.
Results
Twenty-four lower extremities were treated in 23 patients with failed bypass grafts. Average patency of the index graft before failure was 647 days (range 5-2758). Mean age was 68 years (range 51-85), 62% were male and 81% had diabetes mellitus (DM). 87.5% of limbs treated had TransAtlantic InterSociety Consensus (TASC) C and D lesions and 62% had multiple lesions. Technical success was achieved in 100%. Mean follow-up was 25.6 months. At follow-up, there were 17 PTA failures, which resulted in: amputation (4), redo-bypass (3), and redo-PTA (11). Freedom from surgical revision and PTA failure was 89% (+/− 0.07 SE) and 28% (+/− 0.09 SE) respectively. PTA secondary patency was 72% (+/− 0.09 SE) and limb-salvage was 81% (+/− 0.08 SE) at both 12 and 24 months. Overall survival was 83% (+/− 0.07 SE) and 77% (+/− 0.09 SE) at 12 and 24 months, respectively.
Conclusions
Endovascular treatment of patients with previously failed bypass grafts results in a high rate of limb salvage. This is a reasonable option in selected patients and the primary choice in those with poor targets, conduit, or excess surgical risk. Endovascular salvage should be considered before proceeding to primary amputation.
The use of tibial or pedal bypass for the treatment of critical limb ischemia has enjoyed a combination of excellent durability with low mortality and exceptional amputation free survival.1 However, not all patients are candidates for open revascularization due to lack of conduit, limited life expectancy, unacceptable surgical risk, or nonambulatory status. More recently, percutaneous transluminal balloon angioplasty (PTA) in the crural location has largely replaced bypass surgery in certain groups.2
The Bypass Versus Angioplasty in Severe Ischemia of the Leg (BASIL) trial recommended that primary PTA might be an appropriate first therapy even if the patient is a good candidate for bypass.3 PTA for limb threatening ischemia in the infrapopliteal location, has demonstrated primary and secondary patency rates of 53% and 83% at 12 months, and 51% and 63% at 36 months with limb salvage rates above 85% at 3 years.4, 5 However, major amputation is still performed in patients with failed attempts at open revascularization, severe comorbidity, extensive tissue loss, or infection and anatomic factors precluding surgery. Approximately, 60% of amputations are performed on patients with previously failed lower extremity bypass grafts.6 We here set forth to investigate the outcomes of PTA in this group of patients.
Methods
We performed a retrospective review of prospectively collected data from July 2004 to October 2007 at the Beth Israel Deaconess Medical Center and identified 24 lower extremities in 23 patients who presented with critical limb ischemia and a failed (occluded) bypass, all of whom underwent ipsilateral infrainguinal PTA of their native circulation. All these patients were immediately scheduled to undergo diagnostic arteriography and were selected to undergo PTA of their native circulation based on surgeon preference, due to symptom severity, conduit availability, presence of serious comorbid condition (worsening renal or cardiac failure, or severe pulmonary disease), and grafts were deemed unsalvageable. Cases in which both treatment of native circulation as well as salvage attempts at the index bypass graft were performed were excluded. Procedures were performed initially in the operating room with a mobile C-Arm (OEC-9800; General Electric Healthcare, Dallas, Tex) unit with DSA capability, but most were done in endovascular suites with fixed Philips (Allura Xper FD20; Eindhoven, The Netherlands) and General Electric (LCV; GE Healthcare, Dallas, Tex) imaging equipment.
Endovascular technique
Contralateral access was used in all or majority of cases. A 5 or 6F sheath is advanced just proximal to the target lesion. The patient is fully heparinized to maintain an ACT > 250 seconds. Long occlusions are typically crossed with .035-inch angled glide wires in the superficial femoral artery (SFA) and popliteal trying to avoid subintimal dissection if possible. Tibial lesions are then preferentially crossed with a .014-inch or .018-inch wire, over which a long, noncompliant low-profile angioplasty balloon sized to match the healthy portion of the artery is advanced, and prolonged inflation to profile over 2 to 3 minutes is performed. Stents were selectively used in cases of post-PTA residual stenosis or flow-limiting dissection. All patients are continued on aspirin indefinitely and given clopidogrel for a minimum of 30 days.
Patient demographics, comorbidities, procedural data, and follow-up information were recorded in a database. Detailed information was obtained by reviewing vascular laboratory data, patient records, and angiographic procedural imaging and included potential risk factors such as number of lesions, location, TASC classification,7, 8 time from bypass, type of conduit, and bypass target (popliteal, tibial, or pedal). Patient symptoms and severity were also included.
Technical success was defined as a residual stenosis less than 30%. Perioperative events including bleeding, myocardial infarction, stroke, or death were recorded. Survival information was obtained from office visits, telephone contacts, or the Social Security Death Index for patients lost to follow-up. Follow-up visit and duplex ultrasounds were scheduled at 1, 3, and 6 months followed by 3- to 6-month intervals thereafter as necessary. Significant restenosis by duplex, defined as a velocity ratio greater than 3.5 (VR = peak systolic velocity at the lesion/peak systolic velocity proximal to lesion), which correlates with greater than 75% stenosis was followed by redo intervention. All other lesions were observed. PTA failure was defined as redo-PTA, surgical revision, or amputation. The choice of intervention was based on surgeon preferences and patient characteristics. Statistical analysis was performed with descriptive, logistic regression, log-rank test, and Kaplan-Meier life-table analyses. This study was approved by the Beth Israel Deaconess Medical Center institutional review board.
Results
We identified 24 lower extremities in 23 patients who underwent infrainguinal PTA of their native circulation for failed bypass grafts with critical limb ischemia. Patient demographics and comorbidities are listed in Table I. Median age was 68 years (range 51-85). Sixty-two percent were (61%) male and 81% had diabetes mellitus (DM). Average patency of the index graft before failure was 21.6 months (range 0.2-92). Only two patients presented in the early postoperative period (within 30 days) with a failed graft. All patients had critical limb ischemia with rest pain, ulcers, or gangrene. No claudicants were included in this cohort.
Table I. Demographics
| No. or Median | % or Range | |
|---|---|---|
| Age (y) | 67 | 51-85 |
| Male | 16 | 62 |
| Comorbidities | ||
 Coronary artery disease | 14 | 58 |
| Diabetes mellitus | 21 | 87 |
| Hypertension | 19 | 79 |
| Hypercholesterolemia | 9 | 37 |
| Chronic renal insufficiency (Cr > 1.2) | 7 | 29 |
| Smoking | 6 | 25 |
| Cancer or hypercoagulable state | 2 | 8 |
| Hemodialysis | 0 | 0 |
| Previous bypass target | ||
| Popliteal | 3 | 12.5 |
| Tibial Pedal | 14 | 58.3 |
| Pedal | 7 | 29.2 |
| PTA most distal target | ||
| Popliteal | 2 | 8.3 |
| Tibial Pedal | 20 | 83.3 |
| Pedal | 2 | 8.3 |
| Multiple targets treated | 20 | 83.3 |
Primary therapy was PTA in all 24 limbs with three requiring a subintimal approach. Twelve (50%) interventions required adjunctive stenting due to residual stenosis or dissection. Eighty-three percent (83%) of limbs treated had multiple lesions (femoral, popliteal, tibial, or pedal) (Table II) and 87% included TASC C and D lesions. Technical success was 100%, with restoration of in-line flow to the foot. There were four (16%) periprocedural myocardial infarctions and one early stent thrombosis (within 4 days), which required reintervention ultimately leading to an early below the knee amputation due to lack of adequate outflow. There were no access site complications or periprocedural deaths. Mean follow-up was 25.6 months (median 25.3 [range 1.3-38 months]). At follow-up, there were 17 PTA failures, which resulted in: amputation (4), redo-bypass (3), and redo-PTA (11). The redo bypasses were all performed to a more distal target vessel than the original bypass and included a femoral to posterior tibial, a below the knee popliteal to dorsalis pedis and a femoral to below the knee popliteal bypass.
Table II. Distribution of lesions treated
| Patients (%) | Femoropopliteal | Tibial | Pedal | |
|---|---|---|---|---|
| Multiple lesions | 20(83.3) | 22 | 23 | 2 |
| Single lesion | 4(16.7) | 1 | 3 | 0 |
| Total | 24(100) | 23 | 26 | 2 |
Kaplan Meier survival analysis demonstrated that freedom from PTA failure (PTA primary patency) was 28% (+/− 0.09 SE), whereas secondary patency was 72.4% (+/− 0.09 SE) at 12 months (Fig 1), while freedom from surgical revision was 89.5% (+/− 0.07 SE) (Fig 2) and limb-salvage was 81.5% (+/− 0.08 SE) at both 12 and 24 months (Fig 3). Overall survival was 83% (+/− 0.07 SE) and 77 % (+/− 0.09 SE) at 12 and 24 months, respectively (Fig 4). The presence of a TASC D lesion in a treated limb, was found to be the only significant risk factor for PTA failure (hazard ratio [HR], 5.98; 95% CI, 1.3-27.0, P =.02) by univariate analysis (Table III). No other variables were found to be significant by multivariate analysis.
Fig 1.
Primary and secondary PTA patency after failed lower extremity bypass.
PTA patency 12 mo 24 mo 36 mo Primary patency No at risk6 5 2 No of events16 0 1 KM estimate0.283 0.283 0.189 Standard error0.097 0.097 0.10 Secondary patency No. at risk12 8 3 No. of events6 0 1 KM estimate0.723 0.723 0.543 Standard error0.096 0.096 0.172 PTA, Percutaneous balloon angioplasty; KM, Kaplan-Meier; SE, standard error.
Fig 2.
Freedom from surgical revision.
Freedom from surgical revision 12 mo 24 mo 36 mo No. at risk 12 8 3 No. of events 2 0 1 KM estimate 0.894 0.894 0.671 Standard error 0.070 0.070 0.200 PTA, Percutaneous balloon angioplasty; KM, Kaplan-Meier; SE, standard error.
Fig 3.
Limb salvage after PTA for failed lower extremity bypass.
Freedom from amputation 12 mo 24 mo 36 mo No. at risk 13 9 5 No. of events 4 0 0 KM estimate 0.814 0.814 0.814 Standard error 0.084 0.084 0.084 PTA, Percutaneous balloon angioplasty; KM, Kaplan-Meier; SE, standard error.
Fig 4.
Overall survival after PTA for failed lower extremity bypass.
Overall Survival 12 mo 24 mo 36 mo No. at risk 18 13 8 No. of events 4 1 1 KM estimate 0.831 0.772 0.701 Standard error 0.077 0.091 0.107 PTA, Percutaneous balloon angioplasty; KM, Kaplan-Meier; SE, standard error.
Table III. Worst lesion treated in a limb: TASC classification and risk of PTA failure
| TASC classification (worst lesion) | No. | % | HR | 95% CI |
|---|---|---|---|---|
| TASC A | 0 | 0 | — | — |
| TASC B | 3 | 11.5 | 0.22 | 0.03-1.7 |
| TASC C | 3 | 11.5 | 0.24 | 0.03-1.8 |
| TASC D | 18 | 69.2 | 5.98 | 1.3-27.0 |
Five patients underwent postprocedure minor amputations, of these, only two ultimately healed. Although the target of the original failed bypass was not identified as a significant risk factor for PTA failure, we found that a previous popliteal bypass was associated with a significantly increased risk to undergo a redo bypass procedure compared with a previous tibial or distal bypass (P < .0001). This is likely a function of the anatomical requirements or lack thereof, to perform such bypasses (ie, target, conduit).
Discussion
Despite continuous improvements in medical and surgical therapies, lower extremity bypass failure remains a challenging problem for vascular surgeons. Redo bypass for stenosis or impending graft failure carries a significant risk for most of these patients with a 25% complication rate, including 12% of cardiac complications and 1% periprocedural mortality, with 66% limb salvage rates at 5 years in cases with critical limb ischemia.9 On the other hand, while PTA of infrainguinal vein grafts is a viable, safe, and effective alternative to preserve graft function with limb salvage rates of 91% at 2 years, it should likely be limited to those patent bypass grafts with favorable anatomical features.10, 11 This leaves a significant number of patients with failed grafts, who are not surgical candidates due to either severe comorbidity or anatomical reasons with very limited opportunity to avoid amputation.
Our study shows that lower extremity PTA in the setting of limb threatening ischemia due to a failed bypass graft is a safe and effective strategy in limb salvage. This makes it a particularly important modality, in those patients who have no other conduit or revascularization options. A contemporary series established how in patients with critical limb ischemia, infrapopliteal PTA demonstrated a limb salvage rate of 84% up to 3 years,5 with the provision that these patients will require very close follow-up and low threshold for reintervention. Taylor et al reported their comparative data between PTA vs amputation for critical limb ischemia with limb salvage rate of 63% and 3.8% mortality in the PTA group at 12 months.12
Despite our relative high periprocedural myocardial infarction rate of 16%, which likely represents the severity of cardiovascular disease in this selected patient cohort, our data compares favorably to the aforementioned, with no perioperative mortality and limb salvage rate of 81% up to 3 years, despite the frequency of highly unfavorable lesions, namely TASC C and D lesions, which we encountered in more than 87% of limbs treated. This certainly correlated with our high rate of stenting (50%) and reintervention due to early PTA failure. Univariate analysis showed a sixfold increased risk of procedural failure with TASC D lesions. These findings are similar to those of Giles et al who found increased risk of stenosis, reintervention, and amputation in this group of patients.5
We also found that the presence of a previous failed bypass, adds to the complexity of the procedure, since the number of lesions that need to be treated increases and the distal target is almost always located further downstream from the previous bypass into a smaller vessel. We here found that angioplasty distal targets (tibial or pedal) were found and treated in 92% of cases, compared with 87% for previous failed bypasses. Careful wire and catheter handling techniques at this level are extremely important in order to achieve procedural success. Long- term outcomes will greatly depend on a very strict follow-up schedule with arterial duplex surveillance and likely reintervention to maintain patency. Our surveillance protocol calls for duplex ultrasounds at 1, 3, and 6 months followed by 3- to 6-month intervals thereafter for these patients.
The small number of patients limited our ability to identify other predictors of PTA failure. Nonetheless, our data clearly states how PTA in patients with limb threatening ischemia whom already have failed bypass grafts and have limited options for revascularization, have improved limb salvage rates as long as they are subjected to a close follow-up regimen and reintervention as needed.
Conclusion
We conclude that endovascular treatment of patients with limb threat and failed bypass grafts leads to a substantially improved rate of limb salvage despite the TASC lesion classification. This is especially true in patients with no realistic surgical redo option and should always be considered before proceeding to amputation.
Author contributions
References
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Competition of interest: none.
PII: S0741-5214(09)00601-6
doi:10.1016/j.jvs.2009.02.238
© 2009 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
