Bypass grafts to the ankle and foot. A personal perspective

The Role of Distal Arterial Reconstruction in Patients With Diabetic Foot Ischemia

The diabetic foot, a common complication that affects patients with diabetes mellitus, is a therapeutic challenge. It places an increasing burden on society; the patient and caregivers as well as health care systems and clinicians are touched by this problem. The management of the diabetic foot with ischemia consequent to peripheral arterial disease is vexing, often leading to successive amputations. Surgical reconstruction of the peripheral arteries has always been a consideration, although the concept of coexistent small vessel disease has prejudiced the notion of offering reconstructive surgery to these patients. This article examines some of the literature relating to bypass surgery with a view to addressing the aforementioned notion. An appraisal of the literature suggests that vascular reconstructive surgery offers benefits to the diabetic patient, albeit these papers have weaknesses related to study design and methodology. Improved studies are indicated to address the role of bypass surgery to help the diabetic patient with foot complications; it is reasonable to hope that our understanding of the fundamental concepts of the pathogenesis of diabetic foot disease will also improve.

Bypass Grafts: The State of the Art

The treatment options for infra-renal arteriosclerotic occlusive (ASO) vascular disease have never been more varied. The history of open revascularization procedures now exceeds 60 years. This represents three generations of vascular surgeons, the most recent of whom have witnessed more than 30 years of endovascular surgery development and dissemination. Both open and endovascular treatments should be considered mature; moreover, we are improving our understanding of the strategies and tactics that lead to the clinical application of one approach instead of the other. There are other important factors in the choice of a treatment modality to be used for a specific patient. Prime among these is evolving patterns of occlusive disease and the increasing severity of arterial calcification.

Clinical outcomes after closed, staged, and open forefoot amputations

BACKGROUND

Surgical approaches for forefoot osteomyelitis include amputation with immediate wound closure or resection followed by either staged re-resection and wound closure or local care of the open wound for secondary healing. This study evaluated the effectiveness of closed, staged, and open forefoot amputations in preventing major leg amputation and identified those variables that are associated with successful limb preservation.

METHODS

From July 2002 to June 2004, 208 patients with forefoot osteomyelitis or gangrene underwent minor amputation according to a standard treatment algorithm. Wounds with limited cellulitis underwent immediate wound closure (CLOSED), wounds with marginally viable soft tissue underwent open amputation followed by wound closure at 2 to 7 days (STAGED), and wounds with tenosynovitis or extensive necrosis underwent débridement with no attempt at wound closure (OPEN). Patient demographics, need for further operative interventions, time to complete healing, and progression to major amputation were recorded.

RESULTS

With four subjects lost to follow-up, 204 patients (98%) (94 CLOSED, 56 STAGED, and 54 OPEN) were monitored to complete healing, major amputation, or death. OPEN amputations had a significantly reduced initial healing rate (37%, P < .001) and a frequent need for repeat operative intervention (43%), although successful limb salvage was ultimately achieved in 70% of the cases. Initial healing in the CLOSED and STAGED amputation groups was similar (71% and 78%, respectively), leading to excellent early limb salvage (86% and 91%). The median time to healing for closed, staged, and open amputations was 1.2, 1.6, and 4.6 months, respectively (P < .001). Follow-up evaluation demonstrated the initial improvements in limb salvage with the CLOSED and STAGED groups were lost, resulting in similar amputation rates among the three groups of 30% to 35% over 36 months.

CONCLUSIONS

Although open amputation of extensive forefoot infections frequently requires repeat operative interventions and a prolonged time to complete healing, this approach provides limb salvage rates approaching those observed for less invasive infections amenable to immediate closure. Staged closure offers an improved time to healing without negatively impacting the risk of major limb amputation. Independent of their initial operative approach, these patients frequently progress to early leg amputation.

Hybrid Peripheral 3D Contrast-Enhanced MR Angiography of Calf and Foot Vasculature

OBJECTIVE

The objective of our study was to describe hybrid peripheral (HyPer) 3D contrast-enhanced MR angiography (CE-MRA) using sagittal acquisition with parallel imaging of the calf and foot station. The benefit of a dedicated sagittal 3D CE-MRA acquisition of the calf and foot was evaluated by assessing the degree of venous contamination and its diagnostic quality compared with standard bolus chase 3D CE-MRA alone.

MATERIALS AND METHODS

Fifty-three patients (99 legs) were scanned with a 1.5-T MR system equipped with a dedicated bilateral lower extremity phased-array coil. First, high-resolution 3D CE-MRA images of the calves and feet were obtained using two separate sagittal slabs with parallel imaging, with a resulting voxel size of 1.4 x 1.0 x 1.0 mm3. Second, standard bolus chase 3D CE-MRA was performed from the abdomen and pelvis station to the calf-foot station. Images were interpreted by two radiologists. The calf-foot arterial trees were divided into 12 segments. Each segment was characterized as diagnostic or nondiagnostic. The degree of venous contamination was assessed as interfering with the diagnosis or not. Paired Student's t test and Wilcoxon's signed rank test were used to test for statistically significant differences between the techniques.

RESULTS

For the left leg (n = 48), the mean number (+/- SD) of diagnosed arterial segments for HyPer 3D CE-MRA was 9.2 +/- 2.3 and for bolus chase 3D CE-MRA, 7.1 +/- 4.2 (p < or = 0.0004). For the right leg (n = 51), the corresponding values were 9.4 +/- 2.2 and 7.6 +/- 3.5 (p < or = 0.0005), respectively. For bolus chase 3D CE-MRA, venous contamination interfered with the diagnosis in 24 of 99 legs, whereas with HyPer 3D CE-MRA, there was no interference. Selective analysis of the dorsalis pedis arteries showed that the number of diagnostic vessels was 62 (62.6%) of 99 for HyPer 3D CE-MRA and 13 (13.1%) of 99 for bolus chase 3D CE-MRA.

CONCLUSION

HyPer 3D CE-MRA is an alternative method for time-resolved high-resolution peripheral CE-MRA in evaluating the trifurcation and feet vessels with no venous contamination.

Hypertrophic Osteoarthropathy Secondary to Vascular Prosthesis Infection

An infected vascular graft is an uncommon association in hypertrophic osteoarthropathy (HOA) but is important because of potential catastrophic complications. Here we describe 3 new patients with HOA secondary to vascular prosthesis infection and review the other 23 patients described in the English literature with this clinical syndrome. The finding of symptoms and signs of localized HOA in patients with arterial prosthesis may be the presenting manifestation of graft sepsis. In most patients the graft is located at the aorta or aortic bifurcation. The initial symptoms are fever, joint pain mainly involving the knees and ankles, clubbing, and in some cases intestinal bleeding. Recurrent abscesses and bacteremia arising in spite of appropriate antimicrobial therapy are prominent infectious signs. Another characteristic feature is the wide variety of bacteria isolated from a single patient. When a polymicrobial enteric flora is isolated from the blood or other tissue, an intestinal origin of infection can be readily suspected. Gallium or leukocyte scans are useful for detecting an abscess around the vascular prosthesis. In some cases, the detection of gas around the graft demonstrated by computed tomography is highly suggestive of prosthesis infection. Mechanisms involved in the pathogenesis of HOA associated with aortic graft infection are unknown. Treatment consists of intravenous antibiotics and surgical replacement of the infected graft. The prognosis of arterial prosthesis infection depends greatly on early diagnosis and treatment before the onset of life-threatening complications. Knowledge of this rare association may lead to an early diagnosis and appropriate management of this serious and often fatal complication.

Preoperative high-frequency duplex scanning of potential pedal target vessels

OBJECTIVE

The aim of this prospective study conducted at a tertiary referral center was to evaluate the efficacy of high-frequency duplex scanning in the preoperative evaluation of potential pedal target vessels. Material and methods The study population consisted of thirty-three consecutive diabetics suffering critical limb ischemia, with indications of infra-popliteal occlusive disease. Duplex ultrasound was performed by an angiologist unaware of any prior imaging procedures. The pedal vessels were divided into four segments. The inner diameter-, the grade of calcification (on a scale from 1-to-3), the maximal systolic velocity, and the resistance index ([V.max syst-V min syst]/V max syst), were assessed by using a 13-MHz probe, and the pedal target vessel best suited for surgery was identified. Results of duplex scanning were compared to (1) the results of selective digital subtraction angiography (DSA) and contrast-enhanced magnetic resonance angiography (CE-MRA) studies interpreted by two radiologists, (2) the site of distal anastomosis predicted by a vascular surgeon according to DSA and CE-MRA studies, (3) the definitive site of distal anastomosis, and (4) early postoperative results (patency at three months).

RESULTS

Duplex scanning depicted significantly more pedal vascular segments than selective DSA- (P =.004, McNemar test). Agreement in predicting the site of distal anastomosis expressed as kappa value as follows: duplex versus DSA/CE-MRA, kappa 0.71;-DSA/CE-MRA versus definitive anastomosis, kappa 0.67; -and duplex versus definitive anastomosis kappa 0.82. Two patients were excluded from surgery as all three imaging modalities failed to demonstrate a pedal target vessel. Two patients had exploratory dissection of a pedal vessel (according to CE-MRA findings) that turned out to be occluded (as predicted by duplex scanning). In one patient the operation had to be terminated due to lack of autologous bypass material. In 31 patients who underwent pedal artery bypass, the resistance index could not be correlated to the run-off as assessed by intra-operative angiography.

CONCLUSIONS

High-frequency duplex focusing on the vacular-morphology is a worthwhile diagnostic tool to evaluate-potential pedal target vessels and extremely helpful when contrast-related methods (selective DSA, CE-MRA) do not sufficiently depict the pedal vasculature.

Emergency Pedal Artery Bypass Grafting

OBJECTIVES

To determine the value of emergency pedal artery bypass.

MATERIAL AND METHODS

Data were drawn from a prospective vascular database. Inclusion criteria were: acute onset of critical forefoot ischemia, emergency surgery, no pre-operative angiographic imaging of the pedal vasculature and attempted revascularisation of a pedal vessel. Follow-up was obtained from outpatient records. The grafts were considered patent if a pedal pulse was palpable.

RESULTS

Eight out of 208 pedal vascular procedures performed between January 1996 and June 2002 were entered into the study. This cohort consisted of 3 women and 5 men (age 23-85 years, median 71). Operations were performed because of thrombo-embolic occlusion of the tibial vasculature (5 patients), severe tibial embolism following a percutaneous angioplasty of the superficial femoral artery, trash foot following aortic reconstruction and acute occlusion of tibial run-off vessels following a crural reconstruction. Two patients suffered an early graft occlusion, one of them resulting in major amputation. At a median follow up of 17 months (10-52 months) the remaining 6 grafts were patent.

CONCLUSIONS

If catheter directed methods (local lysis, aspiration embolectomy) or surgical procedures (embolectomy, tibial bypass) fail to treat critical foot ischemia, pedal probatorial dissection and pedal bypass is worthwhile.

Pedal artery imaging--a comparison of selective digital subtraction angiography, contrast enhanced magnetic resonance angiography and duplex ultrasound

OBJECTIVE

to evaluate selective digital subtraction angiography (DSA), contrast-enhanced magnetic resonance angiography (CE-MRA) and duplex ultrasound (duplex) in preoperative pedal artery imaging.

MATERIAL AND METHODS

DSA, CE-MRA and duplex were studied prospectively in 37 patients suffering from critical leg ischaemia. Two radiologists independently reviewed both the CE-MRA and DSA images. The pedal vessels were scored on a scale from 0 to III (0=vessel not visualised, I=vessel faintly visualised, II=stenosis >50%, III=vessel without relevant stenosis). Duplex ultrasound was performed by an angiologist blind to both the DSA and MRA findings and the pedal arteries were scored 0-III according to their diameter. Each examiner named the pedal artery best suitable for bypass surgery. Agreement in artery assessment was expressed as kappa values. Patency of the bypass at 30 days was used as validation of the artery's suitability as the run-off vessel.

RESULTS

interobserver agreement for DSA (weighted Kappa 0.63, CI 0.53-0.73 and CE-MRA (weighted kappa 0.60, CI 0.5-0.7) was moderate to substantial. CE-MRA depicted significantly more vascular segments than DSA (p congruent with 0.0001).In the prediction of the distal outflow vessel duplex and CE-MRA proved to be superior to DSA.

CONCLUSION

because of the moderate inter-observer agreement it may be questionable to regard selective DSA as gold standard imaging procedure in preoperative pedal artery imaging. CE-MRA and duplex are very helpful in assessing the pedal artery morphology and should be used if selective DSA does not sufficiently depict the pedal vasculature.

Optimal waiting period for foot salvage surgery following limb revascularization

It is not clear how soon after bypass surgery tissue perfusion in the ischemic foot is adequate for healing. The purpose of this study was to determine the time interval for tissue to receive adequate oxygenation for healing following limb revascularization. Eleven patients with severe foot ischemia as defined by a transcutaneous oxygen tension (TcPO2) of 30 mm Hg or less were included in the study. TcPO2 measurements were performed prior to the lower extremity bypass and at postoperative day 1, 2, and 3. The mean preoperative value (9.27 mm Hg) was compared with the mean value at postoperative day 1 (17.73 mm Hg), postoperative day 2 (20.36 mm Hg), and postoperative day 3 (36.82 mm Hg) using paired samples t-tests. Statistically significant differences were observed between the mean preoperative TcPO2 measurement and the mean TcPO2 measurement taken on the 3rd postoperative day. The mean TcPO2 level increased from 9.27 mm Hg preoperatively to 36.82 mm Hg by the 3rd postoperative day (p = .001). There was also a statistically significant difference between the mean values on the 2nd (20.36 mm Hg) and 3rd postoperative day (36.82 mm Hg) (p = .002). Despite this finding, 5 of the 11 patients still had individual TcPO2 readings of less than 30 mm Hg on the 3rd postoperative day. Therefore, it can be concluded that in most instances tissue oxygenation reaches an adequate level after waiting at least 3 days following a bypass. Waiting 3 or more days could give adequate time for tissue reperfusion to promote healing of the surgical site.

Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions

Wang Y, Winchester PA, Khilnani NM, et al. Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170-177.

RATIONALE AND OBJECTIVES

To obtain reliable contrast-enhanced peripheral MR angiography for imaging peripheral vascular disease from the abdominal aorta to the pedal arteries.

METHODS

A protocol consisting of contrast-enhanced, dynamic two-dimensional (2D) acquisition at the feet and calf and bolus-chase three-dimensional (3D) acquisition from the abdominal aorta to the calf was developed and applied in patients with peripheral vascular disease. The performance of this integrated protocol was assessed in 89 consecutive patients.

RESULTS

The bolus-chase 3D acquisition was of diagnostic quality in 100% of the acquisitions in the abdomen, 96% in the thigh, and 43% in the calf. The poor quality of the calf acquisitions was due to insufficient spatial resolution, poor arterial signal, and venous contamination. Diagnostic-quality images were obtained in 100% of the dynamic 2D acquisitions of the calf and 98% of the feet.

CONCLUSIONS

The combined dynamic 2D and bolus-chase 3D contrast-enhanced MR angiography technique provides diagnostic images of the entire lower extremity.

Pedal branch artery bypass: a viable limb salvage option

PURPOSE

We reviewed our experience with pedal branch artery (PBA) bypass to confirm the role of these target arteries for limb salvage and to identify patient and technical factors that may be associated with graft patency and limb salvage.

METHODS

In this retrospective study we analyzed 24 vein grafts to PBAs performed from 1988 to 1998 for limb salvage in 23 patients who had no suitable tibial, peroneal, or dorsal pedal target arteries. These PBA grafts were compared with 133 perimalleolar posterior tibial, defined at or below the ankle, or dorsalis pedis bypass grafts performed contemporaneously; the Kaplan-Meier life table was used in the analysis of graft patency and limb salvage. Life table analyses and logistic regression analysis of prognostic patient variables were also performed.

RESULTS

The PBA bypass represented 3% of infrainguinal revascularizations for chronic critical limb ischemia at our institution over the study period. Patients who received PBA bypasses were more likely to be male (92% vs. 69%, P =.02) with lower incidences of overt coronary artery disease (33% vs. 50%, P =.12) and stroke (0% vs 15%, P =.04), and a higher incidence of end-stage renal disease (21% vs 8%, P =.06) than those undergoing perimalleolar bypass. Seventeen percent of PBA bypasses were performed with the anterior lateral malleolar artery, a vessel not previously described as a common bypass target. Two-year primary patency and limb salvage for PBA versus perimalleolar bypass was 70% versus 80% (P =.16) and 78% versus 91% (P = .28), respectively. Patency and limb salvage rates were no different in bypasses with above-knee or below-knee inflow arteries.

CONCLUSION

An autogenous vein bypass to the PBA, though rarely required, provides acceptable primary patency and limb salvage when compared with perimalleolar tibial artery bypass when no suitable, more proximal target arteries are available. The PBA bypass should be considered before major amputation is undertaken.

MR angiography in the evaluation of atherosclerotic peripheral vascular disease

Magnetic resonance (MR) angiography of lower extremity occlusive vascular disease has evolved into a feasible diagnostic imaging option. The previous emphasis on time-of-flight techniques was associated with lengthy acquisition times and artifactual signal losses. Those limitations presented an obstacle to widespread clinical implementation. However, the emergence of rapid imaging sequences combined with gadolinium chelate enhancement offers time-efficient alternatives that can yield a truer representation of the vascular anatomic structure. The technology is now poised to serve as a routine screening study, provided that radiologists understand all factors needed to generate clinically relevant MR angiograms. This article is intended to provide a useful resource directed toward achieving that understanding.

Efficacy of dorsal pedal artery bypass in limb salvage for ischemic heel ulcers

PURPOSE

Although pedal artery bypass has been established as an effective and durable limb salvage procedure, the utility of these bypass grafts in limb salvage, specifically for the difficult problem of heel ulceration, remains undefined.

METHODS

We retrospectively reviewed 432 pedal bypass grafts placed for indications of ischemic gangrene or ulceration isolated to either the forefoot (n = 336) or heel (n = 96). Lesion-healing rates and life-table analysis of survival, patency, and limb salvage were compared for forefoot versus heel lesions. Preoperative angiograms were reviewed to evaluate the influence of an intact pedal arch on heel lesion healing.

RESULTS

Complete healing rates for forefoot and heel lesions were similar (90.5% vs 86.5%, P =.26), with comparable rates of major lower extremity amputation (9.8% vs 9.3%, P =.87). Time to complete healing in the heel lesion group ranged from 13 to 716 days, with a mean of 139 days. Preoperative angiography demonstrated an intact pedal arch in 48.8% of the patients with heel lesions. Healing and graft patency rates in these patients with heel lesions were independent of the presence of an intact arch, with healing rates of 90.2% and 83.7% (P =.38) and 2-year patency rates of 73.4% and 67.0% in complete and incomplete pedal arches, respectively. Comparison of 5-year primary and secondary patency rates between the forefoot and heel lesion groups were essentially identical, with primary rates of 56.9% versus 62.1% (P =.57) and secondary rates of 67.2% versus 60.3% (P =.50), respectively.

CONCLUSION

Bypass grafts to the dorsalis pedis artery provide substantial perfusion to the posterior foot such that the resulting limb salvage and healing rates for revascularized heel lesions is excellent and comparable with those observed for ischemic forefoot pathology.