Bypass Flap Reconstruction, A Novel Technique for Distal Revascularization: Outcome of First 10 Clinical Cases
Article Outline
Combined distal venous bypass grafting and free flap transfer can achieve successful treatment of soft tissue defects due to advanced leg ischemia. However, this combined approach is a complex technique involving multiple anastomoses on the same arterial axis with an increased risk of thrombosis. To reduce this risk, we have proposed a new bypass-flap (BF) reconstruction technique using an arterial graft and a free flap supplied by a collateral branch of the graft. The purpose of this report is to document the outcome in the first 10 patients treated using the BF reconstruction technique. From 2002 to 2004, a total of 10 patients with a mean age of 67 years (range 55-78) were treated using a BF. All patients presented critical ischemia with soft tissue defects resulting in exposure of tendons and muscles on the foot or ankle. Distal anastomosis was made between the distal branch of the BF and the pedal artery in five cases, the posterior tibial artery or plantar artery in four cases, and the peroneal artery in one case. In six cases proximal anastomosis was performed between the leg artery and arterial autograft. In the remaining four cases proximal anastomosis required extension of the bypass using a venous graft. The mean duration of hospitalization was 25 days. During the postoperative period, one patient died due to stercoral peritonitis and one patient required major amputation due to unrelenting sepsis. Bypass occlusion was not observed. Mean follow-up was 24 months (range 14-36). No patient was lost to follow-up and no patient died after the first 30 postoperative days. Follow-up examinations including clinical assessment and Doppler ultrasound imaging were performed at 3 months and every 6 months thereafter. Findings demonstrated bypass patency and healing of the covered defect in all cases. Outcome in this initial series demonstrates the clinical feasibility of the new BF reconstruction technique, which allows revascularization and coverage of tissue defects using a one-piece anatomic unit.
Introduction
In Europe the incidence of critical lower limb ischemia is rising rapidly with the aging of the population. Trophic ulcers are the most frequent manifestation of critical lower limb ischemia.1 Lower limb revascularization can lower the amputation rate by 60%.2 However, revascularization may be insufficient for limb salvage in patients with major soft tissue defects due to severe ischemia. Large infected wounds with exposure of tendons, bones, or joints cannot heal even after successful bypass and local debridement. In these cases, free flap transfer combined with distal venous bypass grafting can provide good results for treatment of soft tissue defects.3, 4 Combined distal bypass and free flap transfer presents a hemodynamic advantage by increasing bypass flow-through as a result of the extra runoff afforded by the denervated free muscle flap.5 However, the combined approach is a complex technique requiring multiple anastomoses on the same arterial axis, resulting in a higher risk of thrombosis in addition to the usual complications associated with the use of venous autografts.
To reduce these disadvantages, we have proposed a new bypass-flap (BF) reconstruction technique.6 This technique uses a single anatomic unit harvested from the thoracodorsal artery axis that includes an arterial graft and a free flap supplied by a collateral branch of the graft (Fig. 1). The arterial autograft includes the subscapular artery extended by the thoracodorsal artery. The free flap is composed of the serratus anterior muscle perfused by the distal branch of the thoracodorsal artery7.
Fig. 1
General hemodynamic conception of BF: one-piece anatomical unit composed of vascular axis forming an arterial graft (bypass) with one or more collateral branches supplying the skin or muscle paddle (flap). This anatomic piece allows revascularization and coverage at the same time and provides hemodynamic advantages.
The purpose of this report is to evaluate the feasibility of the BF reconstruction technique and to document outcome in the first 10 patients treated.
Patients and Methods
From August 2002 to September 2004, a total of 10 patients were treated using the BF technique. There were eight men and two women, with a mean age of 63 years (range 41-78). Risk factors are shown in Table I.
Table I. Age, sex, and preoperative risk factors in patients treated using BF reconstruction
| Factors | Patients |
|---|---|
| Age (years) | 63 (range 41-78) |
| Male gender | 8 |
| Current smoker | 2 |
| Past smoker | 8 |
| Hypertension | 6 |
| Diabetes | 8 |
| Dyslipidemia | 5 |
| Overweight | 2 |
| Total | 10 |
All patients presented critical ischemia due to arterial occlusive disease of the lower extremities with severe ischemic ulceration. Resting pain was present in all cases. Mean ankle blood pressure was 30
mm Hg (range 20-50) and mean transcutaneous partial pressure of oxygen (TcPO2) was 19mm Hg (range 10-28). Four patients had undergone proximal revascularization on the same limb with no effect on critical ischemia. Previous procedures involved femoropopliteal bypass in two cases and superficial femoral artery recanalization in two cases. Three patients had already undergone transmetatarsal amputation and four had undergone toe amputation.
Patient selection for BF was based on three criteria: wound assessment, mapping of arterial lesions, and general status of patient. Wound features considered as indications for BF were tissue loss with exposure of underlying structures: bone, tendon, joint, or cartilage. The surface area of the wound evaluated by application of a transparent film equipped with centimetric tiles varied from 40 to 150cm2 (mean 80cm2). The wound was infected in eight cases and presented a necrotic mummified aspect in two cases. Tissue defects were located on the foot in seven cases and on the distal leg in three cases.
All patients underwent arteriography of the lower extremities using arterial catheterization. Special attention was given to the foot. Indications were based on the existence of distal lesions of leg and foot arteries. The recipient artery for distal anastomosis was the pedal artery in four cases, the posterior tibial artery or plantar artery in four cases, the peroneal artery in one case, and the lateral tarsal artery in one case.
The third patient selection criterion was physical and psychological condition. Daily physical activity and nutritional status were determinant factors in indicating patients for BF. The psychological profile of the patient (cooperative, determined, and informed) also played an important role in selection. Chronic renal insufficiency requiring dialysis was the only absolute contraindication.
Surgical anatomy and harvesting technique for BF were described previously.6, 7 Revascularization was achieved using the BF piece alone in most cases (six patients) with relatively short leg artery lesions (Fig. 2). The mean length of the arterial autograft was 12.5cm (range 8.5-15.5). In the remaining four cases with more extensive occlusive lesions, the proximal part of the graft was extended using a great saphenous vein graft (Fig. 3).
Fig. 2
A Ischemic tissue defect on forefoot. B Preoperative arteriography showing occlusion of posterior tibial artery and stenotic lesions of the anterior tibial artery, which is occluded at the level of the ankle. The pedal artery is filled by backflow. C Intraoperative image of muscle flap covering tissue defect on forefoot. D Sketch of BF revascularizing the pedal artery from the anterior tibial artery. E Image showing flap on postoperative day 16. F Follow-up arteriograph made 16 months after the BF reconstruction showing patency of the bypass between the anterior tibial artery and pedal artery (open arrowhead) and permeability of the flap pedicle (solid arrowhead).
Fig. 3
A Ischemic tissue defect on forefoot. B View of wound after debridement; exposure of underlying forefoot bones. C Preoperative arteriograph showing leg arteries; the plantar artery is filled by backflow. D Intraoperative image of BF with pedicle. E Image showing flap before application of skin graft on postoperative day 2. F Sketch of a BF revascularizing the plantar artery from the distal popliteal artery after extension of the bypass artery using a venous graft. G Image showing foot 19 months after the procedure. H, I Arteriographs 19 months after the procedure. H BF assembly: vein graft, arterial autograft, and flap pedicle. I Detail showing distal anastomosis of the BF (open arrowhead) and the flap pedicle (solid arrowhead).
Distal anastomosis was performed between the distal branch of the BF and the pedal artery in five cases, the posterior tibial or plantar artery in four cases, and the peroneal artery in one case. The proximal anastomosis was performed on a leg artery in six cases and on the popliteal or superficial femoral artery in four cases. An operative microscope and microsurgical instrumentation were used in all cases, especially for anastomosis of the vein of the serratus anterior muscle flap on one of the deep foot or leg veins. Intraoperative arteriography was routinely performed to check technical quality.
The mean duration of the procedure was 5hr (range 200-390min). During the postoperative period patients were treated with intravenous unfractionated heparin for 48hr, followed by aspirin. One week after the procedure a skin graft was applied over the muscle flap. A split-thickness skin graft was used in eight cases. A full-thickness graft was used to cover the weight-bearing surface of the forefoot in two cases.
Follow-up including clinical examination and Doppler ultrasound imaging was carried out at 3 months and every 6 months thereafter. At least one control arteriography was performed in all patients within 11-32 months after the procedure. Study end points included patency, limb salvage, distal pressure change, and healing of tissue defects.
Results
One patient died within the first 30 postoperative days due to stercoral peritonitis that was unrelated to the procedure. The mean duration of hospitalization was 25 days (range 14-42) and the mean delay for resumption of ambulation was 15 days (range 10-21). Healing of the tissue defect was obtained in all patients within a mean interval of 35 days (range 20-60) after the procedure. Recurrent infection of the flap was never observed. Wound dehiscence at the great saphenous vein graft donor site on the thigh was observed in one patient and treated by assisted healing. Reoperation was not required in any case. Bypass patency was confirmed by Doppler ultrasound in all cases. Mean postoperative ankle pressure was 110mm Hg (range 90-140), with a mean increase of 60mm Hg (range 40-110) in comparison with preoperative ankle pressure.
The mean follow-up period was 26 months (range 12-34). No patients were lost to follow-up or died after the postoperative period. One patient required major amputation 5 months after the procedure due to unrelenting sepsis at the level of the knee with exposure of the tibia and joint (Table II).
Table II. Outcome of lower extremity revascularization using BF reconstruction in 10 patients
| Number | Age (years) | Gender | Location of ischemic ulcer | Revascularization material | Donor artery | Recipient artery | Patency | Stable healing | Limb salvage | Follow-up (months) |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 55 | Male | Leg | BF | Anterior tibial | Pedal | Yes | Yes | Yes | 36 |
| 2 | 73 | Male | Foot | BF + vein graft | Popliteal | Pedal | Yes | Yes | Yes | 32 |
| 3 | 41 | Male | Leg | BF | Posterior tibial | Peroneal | Yes | Yes | Yes | 28 |
| 4 | 68 | Male | Foot | BF + vein graft | Popliteal | Posterior tibial | Yes | Yes | Yes | 27 |
| 5 | 71 | Male | Foot | BF | Anterior tibial | Posterior tibial | Yes | Yes | Yes | 25 |
| 6 | 76 | Male | Foot | BF | Anterior tibial | Pedal | Yes | Yes | Yes | Died at 2 |
| 7 | 43 | Male | Leg | BF | Posterior tibial | Posterior tibial | Yes | Yes | Yes | 23 |
| 8 | 72 | Female | Foot | BF +vein graft | Femoral | Pedal | Yes | Yes | Yes | 21 |
| 9 | 78 | Female | Foot | BF | Anterior tibial | Lateral tarsal | Yes | Yes | Yes | 19 |
| 10 | 57 | Male | Foot | BF + vein graft | Femoral | Posterior tibial | Yes | Yes | Amputation (4 months) | 14 |
The BF was patent, and the ischemic lesions on the foot healed. No secondary procedures were required. In all patients (n=9) control arteriography during the first postoperative month confirmed patency and absence of bypass defects. Stable healing was obtained in all patients. The physical appearance of the muscle flap changed during follow-up. During the first 2 weeks the flap was usually erythematous, swollen, and warm. Disappearance of edema and return of normal skin color did not occur before postoperative day 21. The interval necessary for swelling of the muscle flap to decrease was 3-18 months after the procedure. The aesthetic appearance of the flap was acceptable for all patients.
At the end of this study (mean 26 months, range 12-34), healing of ischemic lesions was stable and all patients were able to ambulate normally. Follow-up arteriography carried out at a mean interval of 16 months (range 11-32) after the procedure in the nine surviving patients who survived the postoperative period demonstrated patency and absence of defects in all cases. No reoperation was required.
Discussion
The exact role of distal bypass grafting associated with free flap transfer for treatment of tissue defects due to advanced lower limb ischemia is still unclear. Support for the use of this combined technique comes from relatively short series with fewer than 100 cases, no control, and no actuarial analysis of results.3, 4, 8, 9 Most investigators have considered association with diabetes or end-stage renal insufficiency requiring dialysis as absolute and relative contraindications for this technique.4, 9 In our opinion the most important factor is the patient's psychological profile and desire to maintain autonomy, although this is subjective and difficult to determine. Notwithstanding patient selection, the association of bypass grafting and free tissue transfer constitutes a promising alternative9 to amputation in patients with otherwise nonreconstructible lesions.
From a technical standpoint, several investigators9, 10, 11 have advocated performing revascularization and flap transfer during the same procedure as opposed to a two-stage approach. The advantages of single-stage treatment are to avoid reintervention in a fibrotic operating field, to reduce the anesthetic risks associated with repeat procedures, and to shorten the duration of hospitalization. The greatest advantage of the combined technique involves hemodynamics since the presence of a flap on the bypass increases bypass flow-through by reducing distal resistance. This effect was confirmed in a prospective hemodynamic study5 showing a 50% increase in bypass flow-through after placement of a muscle flap. The decrease in distal resistance and increase in patency rate after combined surgery have also been confirmed in animal studies.12
The BF reconstruction technique that we propose and used to achieve the results described herein involves a single anatomic graft consisting of both an arterial bypass and a cutaneous or muscle flap supplied by one or more branches of the bypass (Fig. 1). This technique has the same advantages as the combined venous bypass grafting and free-flap transfer technique. However, it is simpler, since there are fewer anastomoses, and has the additional advantage of using only autologous arterial material if possible.
The greater effectiveness of arterial autografts in comparison with venous grafts has been confirmed by clinical and experimental studies.13 The relative stiffness of the vein graft walls in comparison with arterial graft walls represents a major biomechanical drawback that can cause turbulence with subsequent graft deterioration.14, 15 Major clinical studies with long-term follow-up after coronary bypass have also confirmed the superiority of arterial grafts.16, 17 A recent study18 documented the benefit of arterial autografts for distal revascularization of the lower extremities.
The choice of flap depends on location and type of tissue defect. Fasciocutaneous flaps from the radial artery have been used to treat arterial lesions associated with ischemic ulcers.19 However, this type of flap can only be used for treatment of tissue defects occurring along the axis of bypass revascularization zone since the cutaneous paddle of the flap is perfused by short septal branches of the radial artery and is inseparable from the axis of the radial artery. Fasciocutaneous flaps are unsuitable for coverage of distal wounds or wounds located outside the axis of the bypass. Other fasciocutaneous flaps are less resistant under these difficult conditions. Myocutaneous flaps are unsuitable for coverage of tissue defects on the foot or ankle due to the thickness of the flap and to the slip-sliding effect that impairs ambulation.
Techniques using great dorsal muscle and scapular territory flaps with arterial T or Y grafts have been reported.20, 21, 22, 23 However, the arterial graft is short in this configuration and the branch supplying the flap is located in the proximal part of the graft. As a result, the hemodynamic benefits are lost.
Use of the thoracodorsal arterial axis is more effective. We carried out a preliminary study of the anatomic feasibility of BF using an anatomical unit based on the thoracodorsal artery axis that includes the subscapular artery, thoracodorsal artery, and its distal branch to the great serratus muscle.7 Using this method, the mean length of the available arterial graft was 13cm (range 8.5-15.5) including the subscapular artery and thoracodorsal artery. The length of the pedicle of the great serratus anterior muscle flap was 7.5cm (range 3.0-12.5).
The clinical results reported here demonstrate the effectiveness of our BF technique for limb salvage. Short-term and middle-term follow-up demonstrated graft patency and wound healing in all cases. Only one leg amputation was performed for complications that were not directly linked to the BF technique. In comparison with surgery combining venous bypass and flap transfer, this technique is simpler, since fewer anastomoses are required, and has the additional advantage of using autologous arterial material of an appropriate diameter. Regular tapering characteristic of the BF arterial graft facilitates matching of the bypass and recipient artery diameter. The distal anastomosis, which is one of the most vulnerable parts of the bypass, is made between two homologous vessels, i.e., the distal branch of the BF and the recipient foot artery. Under these conditions, the bypass artery and recipient artery have similar diameters and wall structure. If a longer artery autograft is needed, the BF can be extended using a venous graft. The proximal diameter of the BF is compatible with the diameter of the saphenous vein. This type of extension was required in four out of 10 patients in our series.
The area surrounding the ischemic lesions and bypass pathway can jeopardize the assembly by exposure of the graft in case of sepsis-related wound dehiscence.24 In three cases in this series we covered part of the bypass and tissue defect using the same muscle flap. In all three cases revascularization was performed on the pedal artery in the distal part of a foot that had already undergone transmetatarsal amputation (Fig. 2). Wound healing was obtained and no surgical revision was required. It can be speculated that the presence of autologous artery material and the absence of anastomosis between the bypass and flap in the vicinity of the coverage site contributed to this successful outcome.
Conclusion
This study demonstrates the clinical feasibility of a novel BF reconstruction technique allowing revascularization and coverage of tissue defects using a one-piece anatomic unit. By decreasing distal resistance, this technique provides the same hemodynamic advantages as combined arterial reconstruction and free tissue transfer. It is also simpler, since fewer anastomoses are required, and has the additional advantage of using autologous artery material with a similar diameter, especially for the distal anastomosis.
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Presented at the Twentieth Annual Meeting of the French Society for Vascular Surgery, Lyon, France, May 30-31, 2005.
PII: S0890-5096(09)00247-7
doi:10.1016/j.avsg.2009.09.002
© 2009 Published by Elsevier Inc.
