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The Distaflo graft: A valid alternative to interposition vein?
Eur J Vasc Endovasc Surg 25, 235±239 (2003) doi:10.1053/ejvs.2002.1840, available online at http://www.sciencedirect.com on
The Distaflo Graft: a Valid Alternative to Interposition Vein? R. K. Fisher, U. J. Kirkpatrick, T. V. How, J. A. Brennan, G. L. Gilling-Smith and P. L. Harris Regional Vascular Unit, Royal Liverpool University Hospital, U.K. Introduction: the rationale behind the Distaflo graft is inhibition of myointimal hyperplasia through optimisation of haemodynamic forces at the distal anastomosis. This prospective study reports our early clinical results. Method: patients with critical limb ischaemia, but no autologous vein, underwent infrainguinal bypass using Distaflo. Clinical and Duplex assessment provided prospective data from which one year cumulative patency, limb salvage and survival rates were calculated using Kaplan±Meier analysis. Log rank test enabled comparison with an historical control group of Miller cuff grafts. Results: fifty Distaflo were inserted over 29 months into 46 patients, median age 68.5 years, 27 male (59%), of which 27 (54%) were re-do procedures. Proximal anastomoses were to common femoral arteries in 40 cases (80%); distal anastomoses were to popliteal vessels in 20 (40%), and tibial vessels in 30 (60%). The Distaflo graft had patency, limb salvage and survival rates of 39, 50 and 82% respectively compared to 49, 56 and 85% respectively in the control group, with no statistical difference (p 0.39; 0.65; 0.67 respectively; log rank). Conclusion: in this non-randomised study, the Distaflo has similar one year patency, limb salvage and survival rates to the Miller cuff, potentially justifying its use an alternative in distal prosthetic arterial reconstruction for critical limb ischaemia. Key Words: Critical limb ischaemia; Femorodistal bypass; Haemodynamics; Precuffed; Distaflo.
Introduction The improved patency rates of an infragenicular Miller cuff over an end-to-side prosthetic graft anastomosis has been attributed, in part at least, to the presence of the unique vortical flow pattern which increases wall shear stress (WSS) at critical points within the anastomosis, namely the heel, toe and along the recipient artery floor.1±3 There is strong evidence supporting an inverse relationship between WSS and the development of myointimal hyperplasia (MIH), and the rationale behind the Distaflo graft is optimisation of haemodynamic forces at the distal anastomosis, thereby inhibiting occlusive MIH.4±9 The vortex, deemed to be beneficial in the Miller cuff, has been shown to be replicated in the majority of in vivo Distaflo grafts, which are now widely used as an alternative to interposition vein in the treatment of critical limb ischaemia.9 There remains, however, no clinical data upon the outcome of the Distaflo graft.
Please address all correspondence to: R. K. Fisher, c/o Secretary to Mr Brennan, Regional Vascular Unit, 8C Link, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP.
The aim of this study was to report the short-term outcome of the Distaflo graft and to explore whether it offers a valid alternative to the interposition of vein in the treatment of critical limb ischaemia at our institution.
Patients and Methods The Distaflo graft was introduced into our clinical practice in January 1999, replacing the routine interposition of vein with femorodistal PTFE bypass. This study was initiated upon insertion of the first graft, and was carried out prospectively on an intention to treat basis. Inclusion criteria were patients presenting with critical limb ischaemia, as classified by the Second European consensus 1992,10 suitable for infrainguinal arterial reconstruction on the basis of clinical and intra-arterial digital subtraction angiographical (IADSA) examination, and consenting to inclusion into the study. In keeping with guidelines set out by the TransAtlantic Inter-Society Consensus (TASC) on the treatment of critical limb ischaemia, arterial lesions amenable to radiological interventions, and
1078±5884/03/030235 05 $35.00/0 # 2003 Elsevier Science Ltd. All rights reserved.
R. K. Fisher et al.
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autologous ipsilateral great saphenous or basilicocephalic arm vein of adequate quality constituted exclusion criteria.11 Regional ethical approval for the study was gained. Recognised techniques for exposure of the arteries and tunnelling of grafts were employed, with 5000 Units of intravenous Heparin routinely infused intraoperatively. Evidence does not support routine postoperative anticoagulation after prosthetic bypass, although all patients were discharged on anti-platelet medication. The study group comprised of a consecutive series of 50 Distaflo grafts, over 29 months. Patient demographics, pathophysiological parameters and anastomotic levels are summarised in Tables 1 and 2. Follow up included Duplex assessment and clinical review, and provided one year outcome measures including cumulative graft patency, limb salvage and patient survival, expressed as Kaplan±Meier survival curves. Interrogation of the audit database at our institution enabled the compilation of an historical control group of infrainguinal Miller cuff grafts (Tables 1 and 2) for the 5-year period immediately prior to the introduction of the Distaflo graft. Matching for age, gender,
Table 1. Patient demographics and clinical features in the Distaflo and Miller cuff groups.
Total Patients Limbs Male: female Median age (range) Diabetes Rest pain Necrosis Primary procedure Re-do procedure 1 previous procedure 41 previous procedure Total previous procedures Single run-off vessel
Distaflo
Miller cuff
50 46 47 1.4: 1 68.5 yrs (40±90) 16 (35) 46 (92) 26 (52) 23 (46) 27 (54) 16 (32) 11 (22) 48 31 (62)
50 47 49 1.9: 1 67 yrs (45±86) 9 (19) 46 (92) 28 (56) 24 (48) 26 (52) 15 (30) 11 (22) 41 28 (56)
Percentages quoted in parentheses. Table 2. Distal anastomotic vessel. Distal vessel
Distaflo
Miller cuff
Above knee popliteal Below knee popliteal Anterior tibial Tibio-peroneal trunk Posterior tibial Peroneal Total infragenicular
7 (14) 13 (26) 12 (24) 3 (6) 7 (14) 8 (16) 30 (60)
2 (4) 17 (34) 12 (24) 1 (2) 8 (16) 10 (20) 31 (62)
Percentages quoted in parentheses. Eur J Vasc Endovasc Surg Vol 25, March 2003
risk factors and disease severity was attempted. This was performed manually with the selector, UJK, blinded to outcome measures to avoid introducing bias. Statistical comparison between survival curves was made using log rank tests, p 5 0.05 representing significance (SPSS for Windows release 10, Chicago, Illanois, U.S.A.). Results Twenty-two bypass operations were performed urgently within 7 days of acute admission (44%), 21 were elective (42%) and seven were emergencies within 24 h of admission (14%). Patients had a median American Society of Anaesthesiology score of three. Twenty-seven were re-do operations (54%), with a total of 48 ipsilateral bypass procedures having been undertaken in these limbs. The proximal anastomosis was to the common femoral artery in 40 cases (80%) with the remainder from either the external iliac or the superficial femoral artery. The distal anastomosis involved a crural vessel in 30 bypass procedures (60%) and a popliteal artery in 20 reconstructions (40%). Immediate post-operative complications included haemorrhage and/or haematoma in four patients, anaemia in three, renal, cardiac or pulmonary failure in four, proven myocardial infarction in three and wound dehiscence in a single patient. Three patients required return to theatre to resolve a complication. The 30-day mortality was 4% (two patients) both of whom had fatal myocardial infarctions. The overall mortality was 18% (nine patients) representing 82% one year survival on life table analysis (mean 748 days; 95% CI 654±843). A total of 28 grafts occluded (56%), representing 3, 6 and 12 months cumulative patency rates of 67, 49 and 39% respectively (mean 311 days; 95% CI 207±416). Secondary procedures included re-exploration, thrombectomy or thrombolysis in six bypasses, removal of three infected grafts, revision of a single distal anastomosis and two re-do procedures. Twentythree limbs were deemed unsalvageable and underwent amputation. This decision was based on clinical judgement by the surgeon and subjective input from the patient. Nine amputations were below knee (39%) and 14 above knee (61%), of which two were below knee conversions. Kaplan±Meier life table analysis gave 3, 6 and 12 months limb salvage rates of 74, 59 and 50% respectively. Comparison between the Distaflo group and an historical control group of Miller cuff bypass grafts
1.0
1.0
.9
.9
.8
.8
.7
.7
.6
.6
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Cum Survival
The Distaflo Graft
.5 .4 .3
.5 .4 .3
.2
.2
.1
.1
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.0 0
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Days
0
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50 50 50
38 41 48
28 31 43
15 19 34
10 16 27
follow up grafts at risk Distaflo Miller cuff
Fig. 1. Kaplan±Meier survival curves for Distaflo graft. Patency vs limb salvage p 0.30; log rank (SE510% at all times). Broken line Survival. Solid line limb salvage. Dashed line cumulative patency.
0
30
90
180
365
50 50
38 35
28 27
15 25
10 17
Fig. 3. Kaplan±Meier survival curves comparing cumulative patency of Distaflo and Miller Cuff grafts: p 0.39; log rank (SE510%). Solid line Distaflo. Dashed line Miller cuff.
Discussion
1.0 .9 .8 .7
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150
.6 .5 .4 .3 .2 .1 0.0 0
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0
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20 20
14 14
11* 11*
5* 6*
3* 4*
Fig. 2. Kaplan±Meier survival curves for infragenicular Distaflo grafts with Taylor score 0-4. Patency vs limb salvage p 0.66; log rank (*SE 410% 515%). Solid line salvage. Dashed line cumulative patency.
was not significant. One year cumulative patency, limb salvage and survival rates were 39, 50 and 82% compared to 49, 56 and 85% respectively; p 0.39, 0.65 and 0.67 respectively: log rank (Figs 1±3).
The 1-year patency and limb salvage rates of the Distaflo graft are comparable to those of the Miller cuff, suggesting that the potential benefits attributed to the vortex are replicated in each. Our results, however, also serve to reiterate the poor prognosis of femorodistal prosthetic bypass grafts as evidenced by the high amputation rate of 46%. Graft failure is multi-factorial, including the accretion of myointimal hyperplasia, progression of distal disease and increased thrombotic threshold velocity of PTFE compared to vein, due in part to increased platelet activation. Through anastomotic engineering and pharmacological manipulation of platelet function we can influence some of these factors to improve patency,12±14 whilst the intrinsic disease processes may be more problematic. The prevalence of risk factors such as hypertension and smoking were high, as expected, and comparable between the two groups. Scrutinising the audit database failed to accurately match for diabetes, with a greater proportion of diabetics in the Distaflo group, and one may expect this to be of detriment to the lifespan of the graft and limb.15±17 There was, however, no observed statistical difference in cumulative patency or limb salvage between the groups. The introduction of a new graft into clinical practice brings with it the need for clinical evaluation. Whilst Eur J Vasc Endovasc Surg Vol 25, March 2003
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R. K. Fisher et al.
this study provides the first short-term clinical data on the Distaflo graft, its power is limited by the incorporation of an historical control. We felt this necessary in order to set the data in context. The relatively low numbers of prosthetic distal reconstructions undertaken annually by a single institute would mean that a randomised controlled trial comparing the Distaflo with the Miller cuff would need to be multi-centred, and run over several years. The early unpublished, but presented data from such a trial in North America concur with our finding of no statistical difference between the two groups.18 One advantage of the new graft is the high conformability of the thinned PTFE in the ``cuff'' which results in improved handling, allowing successful completion of the distal anastomoses in an often hostile anatomical environment. Although the length of arteriotomy required for the Distaflo is greater than that recommended for a Miller cuff, the precuffed graft obviates the need to harvest and create a vein cuff, thereby simplifying the operation.9,19 In a group of patients with a high rate of co-morbidity this can only be of benefit, although similar mortality rates were noted in our two groups. There is no evidence of a clinical benefit in using a Miller cuff to the above knee popliteal artery, however the pathophysiological principles of MIH accretion still apply, and therefore its use is not contraindicated.1,20 The improved handling properties of vein and Distaflo alike have meant that in both groups the surgeon has, on occasion, preferentially used these techniques over an end-to-side anastomosis in order to improve the technical profile of the anastomosis. This has contributed to the heterogeneity of our study groups however the relatively low numbers do not facilitate stratification by distal anastomotic level. The strong evidence supporting the use of vein for infragenicular reconstruction introduces a heavy bias into any study of femorodistal prosthetic graft performance, as a high proportion of the operations are redo procedures.21,22 More than half of our patients had previously undergone at least one ipsilateral bypass, and over one-fifth had two or more previous procedures, and as such represent a group at the more severe end of the disease spectrum. This may be reflected in the steep descent of the patency and limb salvage curves over the first 6 months of graft life. Panayiotopoulos et al. described a ``Taylor score'' based on clinical and radiological parameters that provided a prognostic score for predicting outcome of femorodistal bypass grafts. In their series they reported 100% graft failure at 10 months in those patients scoring in the lowest group. When such a score was applied to our Distaflo group, 40% scored Eur J Vasc Endovasc Surg Vol 25, March 2003
in this worst category, and yet nearly a fifth of these grafts were still patent at one year. Although no scientific conclusion can be drawn from this, it demonstrates some success in adverse conditions and potentially supports our aggressive policy for reconstruction to achieve limb salvage. In conclusion, this study suggests that, in the absence of vein, the Distaflo graft may offer an alternative in prosthetic femorodistal arterial reconstruction, with similar cumulative patency, limb salvage and survival rates to the Miller cuff. Results of a randomised control trial are required before more definitive conclusions can be made.
References 1 Stonebridge PA, Howlett R, Prescott R, Ruckley CV. Randomised trial comparing polytetrafluoroethylene graft patency with and without a Miller cuff. Br J Surg 1995; 82: 555±556. 2 Da Silva AF, Carpenter T, How TV, Harris PL. Stable vortices within vein cuffs inhibit anastomotic myointimal hyperplasia? Eur J Vasc Endovasc Surg 1997; 14: 157±163. 3 How TV, Rowe C, Gilling-Smith GL, Harris PL. Interposition vein cuff anastomosis alters wall shear stress distribution in recipient artery. J Vasc Surg 2000; 31: 1008±1018. 4 Zarins CK, Zatina MA, Giddens DP, Ku DN, Glagov S. Shear stress regulation of artery lumen diameter in experimental atherogenesis. J Vasc Surg 1987; 5: 413±420. 5 Sottiurai VS. Distal anastomotic intimal hyperplasia: histocytomorphology, pathophysiology, etiology and prevention. Int J Angiol 1999; 8: 1±10. 6 Pedersen EM, Oyre S, Agerbaek M et al. Distribution of early atherosclerotic lesions in the human abdominal aorta correlates with wall shear stresses measured in vivo. Eur J Vasc Endovasc Surg 1999; 18: 328±333. 7 Kraiss LW, Kirkman T, Kohler TR, Zierler B, Clowes AW. Shear stress regulates smooth muscle proliferation and neointimal thickening in porous polytetrafluoroethylene grafts. Arterioscler Thromb 1991; 11: 1844±1852. 8 Kohler TR, Kirkman T, Kraiss LW, Zierler B, Clowes AW. Increased blood flow inhibits neointimal hyperplasia in endothelialised vascular grafts. Circ Res 1991; 69: 1557±1565. 9 Fisher RK, Toonder I, Hoedt M, How TV, Brennan JA, Harris PL. Harnessing haemodynamics for the suppression of anastomotic intimal hyperplasia: the rationale for precuffed grafts. Eur J Vasc Endovasc Surg 2001; 21: 520±528. 10 Anonymous. Second European Consensus Document on Chronic Critical Limb Ischaemia. Eur J Vasc Surg 1992; 6(A): 1±32. 11 No authors listed. Management of Peripheral Arterial Disease (PAD). TransAtlantic Inter-Society Consensus (TASC). Section D: chronic critical limb ischaemia. Eur J Vasc Endovasc Surg 2000; 19(Suppl A): S144±S243. 12 Arfvidsson B, Lundgren F, Drott C, Schersten T, Lundholm K. Influence of coumarin treatment on patency and limb salvage after peripheral arterial reconstructive surgery. Am J Surg 1990; 159: 556±560. 13 Ktretschmer GJ, Holzenbein T, Huk I, Abela C. What is the evidence that anticoagulant treatment improves long-term patency of distal bypass? In: Greenhalgh RM, Fowkes FGR, eds. Trials and Tribulations of Vascular Surgery. Evidence Based Vascular Surgery. London: Saunders, 1996; 43±52. 14 Sarac TP, Huber T, Back MR et al. Warfarin improves the outcome of infrainguinal vein bypass grafting at high risk of failure. J Vasc Surg 1998; 28: 446±457.
The Distaflo Graft 15 da Silva AF, Desgranges P, Holdsworth J et al. The management of outcome of critical limb ischaemia in diabetic patients: results of a national survey: Audit Committee of the Vascular Surgical Society of Great Britain and Ireland. Diab Med 1996; 13: 726±728. 16 Enzler MA, Ruoss M, Seifert B, Berger M. The influence of gender on the outcome of arterial procedures in the lower extremity. Eur J Vasc Endovasc Surg 1996; 11: 446±452. 17 Jonsson B, Skau T. Outcome of symptomatic leg ischaemia: four year morbidity and mortality in Vadstena, Sweden. Eur J Vasc Endovasc Surg 1996; 11: 315±323. 18 Panneton J. Early results of North American randomised control trial of Distaflo versus interposition vein. In: Greenhalgh R, ed. Vascular and Endovascular Techniques. London: 23rd Charing Cross International Symposium, 2001. 19 Fisher RK, How TV, Carpenter T, Brennan JA, Harris PL. Optimising Miller cuff dimensions. The influence of geometry on
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anastomotic flow patterns. Eur J Vasc Endovasc Surg 2001; 21: 251±260. 20 Suggs WD, Henriques H, DePalma RG. Vein cuff interposition prevents juxta-anastomotic neointimal hyperplasia. Ann Surg 1988; 207: 717±723. 21 Veith FJ, Gupta SK, Ascer E, White-Flores S et al. Six-year prospective multicentre randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial constructions. J Vasc Surg 1986; 3: 104±114. 22 Tilanus HW, Obertop H, van Urk H. Saphenous vein or PTFE for femoropopliteal bypass. A prospective randomized trial. Ann Surg 1985; 202: 780±782.
Accepted 4 December 2002
Eur J Vasc Endovasc Surg Vol 25, March 2003
The Distaflo Graft: a Valid Alternative to Interposition Vein? R. K. Fisher, U. J. Kirkpatrick, T. V. How, J. A. Brennan, G. L. Gilling-Smith and P. L. Harris Regional Vascular Unit, Royal Liverpool University Hospital, U.K. Introduction: the rationale behind the Distaflo graft is inhibition of myointimal hyperplasia through optimisation of haemodynamic forces at the distal anastomosis. This prospective study reports our early clinical results. Method: patients with critical limb ischaemia, but no autologous vein, underwent infrainguinal bypass using Distaflo. Clinical and Duplex assessment provided prospective data from which one year cumulative patency, limb salvage and survival rates were calculated using Kaplan±Meier analysis. Log rank test enabled comparison with an historical control group of Miller cuff grafts. Results: fifty Distaflo were inserted over 29 months into 46 patients, median age 68.5 years, 27 male (59%), of which 27 (54%) were re-do procedures. Proximal anastomoses were to common femoral arteries in 40 cases (80%); distal anastomoses were to popliteal vessels in 20 (40%), and tibial vessels in 30 (60%). The Distaflo graft had patency, limb salvage and survival rates of 39, 50 and 82% respectively compared to 49, 56 and 85% respectively in the control group, with no statistical difference (p 0.39; 0.65; 0.67 respectively; log rank). Conclusion: in this non-randomised study, the Distaflo has similar one year patency, limb salvage and survival rates to the Miller cuff, potentially justifying its use an alternative in distal prosthetic arterial reconstruction for critical limb ischaemia. Key Words: Critical limb ischaemia; Femorodistal bypass; Haemodynamics; Precuffed; Distaflo.
Introduction The improved patency rates of an infragenicular Miller cuff over an end-to-side prosthetic graft anastomosis has been attributed, in part at least, to the presence of the unique vortical flow pattern which increases wall shear stress (WSS) at critical points within the anastomosis, namely the heel, toe and along the recipient artery floor.1±3 There is strong evidence supporting an inverse relationship between WSS and the development of myointimal hyperplasia (MIH), and the rationale behind the Distaflo graft is optimisation of haemodynamic forces at the distal anastomosis, thereby inhibiting occlusive MIH.4±9 The vortex, deemed to be beneficial in the Miller cuff, has been shown to be replicated in the majority of in vivo Distaflo grafts, which are now widely used as an alternative to interposition vein in the treatment of critical limb ischaemia.9 There remains, however, no clinical data upon the outcome of the Distaflo graft.
Please address all correspondence to: R. K. Fisher, c/o Secretary to Mr Brennan, Regional Vascular Unit, 8C Link, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP.
The aim of this study was to report the short-term outcome of the Distaflo graft and to explore whether it offers a valid alternative to the interposition of vein in the treatment of critical limb ischaemia at our institution.
Patients and Methods The Distaflo graft was introduced into our clinical practice in January 1999, replacing the routine interposition of vein with femorodistal PTFE bypass. This study was initiated upon insertion of the first graft, and was carried out prospectively on an intention to treat basis. Inclusion criteria were patients presenting with critical limb ischaemia, as classified by the Second European consensus 1992,10 suitable for infrainguinal arterial reconstruction on the basis of clinical and intra-arterial digital subtraction angiographical (IADSA) examination, and consenting to inclusion into the study. In keeping with guidelines set out by the TransAtlantic Inter-Society Consensus (TASC) on the treatment of critical limb ischaemia, arterial lesions amenable to radiological interventions, and
1078±5884/03/030235 05 $35.00/0 # 2003 Elsevier Science Ltd. All rights reserved.
R. K. Fisher et al.
236
autologous ipsilateral great saphenous or basilicocephalic arm vein of adequate quality constituted exclusion criteria.11 Regional ethical approval for the study was gained. Recognised techniques for exposure of the arteries and tunnelling of grafts were employed, with 5000 Units of intravenous Heparin routinely infused intraoperatively. Evidence does not support routine postoperative anticoagulation after prosthetic bypass, although all patients were discharged on anti-platelet medication. The study group comprised of a consecutive series of 50 Distaflo grafts, over 29 months. Patient demographics, pathophysiological parameters and anastomotic levels are summarised in Tables 1 and 2. Follow up included Duplex assessment and clinical review, and provided one year outcome measures including cumulative graft patency, limb salvage and patient survival, expressed as Kaplan±Meier survival curves. Interrogation of the audit database at our institution enabled the compilation of an historical control group of infrainguinal Miller cuff grafts (Tables 1 and 2) for the 5-year period immediately prior to the introduction of the Distaflo graft. Matching for age, gender,
Table 1. Patient demographics and clinical features in the Distaflo and Miller cuff groups.
Total Patients Limbs Male: female Median age (range) Diabetes Rest pain Necrosis Primary procedure Re-do procedure 1 previous procedure 41 previous procedure Total previous procedures Single run-off vessel
Distaflo
Miller cuff
50 46 47 1.4: 1 68.5 yrs (40±90) 16 (35) 46 (92) 26 (52) 23 (46) 27 (54) 16 (32) 11 (22) 48 31 (62)
50 47 49 1.9: 1 67 yrs (45±86) 9 (19) 46 (92) 28 (56) 24 (48) 26 (52) 15 (30) 11 (22) 41 28 (56)
Percentages quoted in parentheses. Table 2. Distal anastomotic vessel. Distal vessel
Distaflo
Miller cuff
Above knee popliteal Below knee popliteal Anterior tibial Tibio-peroneal trunk Posterior tibial Peroneal Total infragenicular
7 (14) 13 (26) 12 (24) 3 (6) 7 (14) 8 (16) 30 (60)
2 (4) 17 (34) 12 (24) 1 (2) 8 (16) 10 (20) 31 (62)
Percentages quoted in parentheses. Eur J Vasc Endovasc Surg Vol 25, March 2003
risk factors and disease severity was attempted. This was performed manually with the selector, UJK, blinded to outcome measures to avoid introducing bias. Statistical comparison between survival curves was made using log rank tests, p 5 0.05 representing significance (SPSS for Windows release 10, Chicago, Illanois, U.S.A.). Results Twenty-two bypass operations were performed urgently within 7 days of acute admission (44%), 21 were elective (42%) and seven were emergencies within 24 h of admission (14%). Patients had a median American Society of Anaesthesiology score of three. Twenty-seven were re-do operations (54%), with a total of 48 ipsilateral bypass procedures having been undertaken in these limbs. The proximal anastomosis was to the common femoral artery in 40 cases (80%) with the remainder from either the external iliac or the superficial femoral artery. The distal anastomosis involved a crural vessel in 30 bypass procedures (60%) and a popliteal artery in 20 reconstructions (40%). Immediate post-operative complications included haemorrhage and/or haematoma in four patients, anaemia in three, renal, cardiac or pulmonary failure in four, proven myocardial infarction in three and wound dehiscence in a single patient. Three patients required return to theatre to resolve a complication. The 30-day mortality was 4% (two patients) both of whom had fatal myocardial infarctions. The overall mortality was 18% (nine patients) representing 82% one year survival on life table analysis (mean 748 days; 95% CI 654±843). A total of 28 grafts occluded (56%), representing 3, 6 and 12 months cumulative patency rates of 67, 49 and 39% respectively (mean 311 days; 95% CI 207±416). Secondary procedures included re-exploration, thrombectomy or thrombolysis in six bypasses, removal of three infected grafts, revision of a single distal anastomosis and two re-do procedures. Twentythree limbs were deemed unsalvageable and underwent amputation. This decision was based on clinical judgement by the surgeon and subjective input from the patient. Nine amputations were below knee (39%) and 14 above knee (61%), of which two were below knee conversions. Kaplan±Meier life table analysis gave 3, 6 and 12 months limb salvage rates of 74, 59 and 50% respectively. Comparison between the Distaflo group and an historical control group of Miller cuff bypass grafts
1.0
1.0
.9
.9
.8
.8
.7
.7
.6
.6
Cum Patency
Cum Survival
The Distaflo Graft
.5 .4 .3
.5 .4 .3
.2
.2
.1
.1
0.0
237
.0 0
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60
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180 210
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Days follow up grafts at risk patency salvage survival
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330
360
390
Days
0
30
90
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365
50 50 50
38 41 48
28 31 43
15 19 34
10 16 27
follow up grafts at risk Distaflo Miller cuff
Fig. 1. Kaplan±Meier survival curves for Distaflo graft. Patency vs limb salvage p 0.30; log rank (SE510% at all times). Broken line Survival. Solid line limb salvage. Dashed line cumulative patency.
0
30
90
180
365
50 50
38 35
28 27
15 25
10 17
Fig. 3. Kaplan±Meier survival curves comparing cumulative patency of Distaflo and Miller Cuff grafts: p 0.39; log rank (SE510%). Solid line Distaflo. Dashed line Miller cuff.
Discussion
1.0 .9 .8 .7
Cum Survival
150
.6 .5 .4 .3 .2 .1 0.0 0
30
60
90
120
150
180 210
240
270
300
330
360
390
Days follow up grafts at risk patency salvage
0
30
90
180
365
20 20
14 14
11* 11*
5* 6*
3* 4*
Fig. 2. Kaplan±Meier survival curves for infragenicular Distaflo grafts with Taylor score 0-4. Patency vs limb salvage p 0.66; log rank (*SE 410% 515%). Solid line salvage. Dashed line cumulative patency.
was not significant. One year cumulative patency, limb salvage and survival rates were 39, 50 and 82% compared to 49, 56 and 85% respectively; p 0.39, 0.65 and 0.67 respectively: log rank (Figs 1±3).
The 1-year patency and limb salvage rates of the Distaflo graft are comparable to those of the Miller cuff, suggesting that the potential benefits attributed to the vortex are replicated in each. Our results, however, also serve to reiterate the poor prognosis of femorodistal prosthetic bypass grafts as evidenced by the high amputation rate of 46%. Graft failure is multi-factorial, including the accretion of myointimal hyperplasia, progression of distal disease and increased thrombotic threshold velocity of PTFE compared to vein, due in part to increased platelet activation. Through anastomotic engineering and pharmacological manipulation of platelet function we can influence some of these factors to improve patency,12±14 whilst the intrinsic disease processes may be more problematic. The prevalence of risk factors such as hypertension and smoking were high, as expected, and comparable between the two groups. Scrutinising the audit database failed to accurately match for diabetes, with a greater proportion of diabetics in the Distaflo group, and one may expect this to be of detriment to the lifespan of the graft and limb.15±17 There was, however, no observed statistical difference in cumulative patency or limb salvage between the groups. The introduction of a new graft into clinical practice brings with it the need for clinical evaluation. Whilst Eur J Vasc Endovasc Surg Vol 25, March 2003
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this study provides the first short-term clinical data on the Distaflo graft, its power is limited by the incorporation of an historical control. We felt this necessary in order to set the data in context. The relatively low numbers of prosthetic distal reconstructions undertaken annually by a single institute would mean that a randomised controlled trial comparing the Distaflo with the Miller cuff would need to be multi-centred, and run over several years. The early unpublished, but presented data from such a trial in North America concur with our finding of no statistical difference between the two groups.18 One advantage of the new graft is the high conformability of the thinned PTFE in the ``cuff'' which results in improved handling, allowing successful completion of the distal anastomoses in an often hostile anatomical environment. Although the length of arteriotomy required for the Distaflo is greater than that recommended for a Miller cuff, the precuffed graft obviates the need to harvest and create a vein cuff, thereby simplifying the operation.9,19 In a group of patients with a high rate of co-morbidity this can only be of benefit, although similar mortality rates were noted in our two groups. There is no evidence of a clinical benefit in using a Miller cuff to the above knee popliteal artery, however the pathophysiological principles of MIH accretion still apply, and therefore its use is not contraindicated.1,20 The improved handling properties of vein and Distaflo alike have meant that in both groups the surgeon has, on occasion, preferentially used these techniques over an end-to-side anastomosis in order to improve the technical profile of the anastomosis. This has contributed to the heterogeneity of our study groups however the relatively low numbers do not facilitate stratification by distal anastomotic level. The strong evidence supporting the use of vein for infragenicular reconstruction introduces a heavy bias into any study of femorodistal prosthetic graft performance, as a high proportion of the operations are redo procedures.21,22 More than half of our patients had previously undergone at least one ipsilateral bypass, and over one-fifth had two or more previous procedures, and as such represent a group at the more severe end of the disease spectrum. This may be reflected in the steep descent of the patency and limb salvage curves over the first 6 months of graft life. Panayiotopoulos et al. described a ``Taylor score'' based on clinical and radiological parameters that provided a prognostic score for predicting outcome of femorodistal bypass grafts. In their series they reported 100% graft failure at 10 months in those patients scoring in the lowest group. When such a score was applied to our Distaflo group, 40% scored Eur J Vasc Endovasc Surg Vol 25, March 2003
in this worst category, and yet nearly a fifth of these grafts were still patent at one year. Although no scientific conclusion can be drawn from this, it demonstrates some success in adverse conditions and potentially supports our aggressive policy for reconstruction to achieve limb salvage. In conclusion, this study suggests that, in the absence of vein, the Distaflo graft may offer an alternative in prosthetic femorodistal arterial reconstruction, with similar cumulative patency, limb salvage and survival rates to the Miller cuff. Results of a randomised control trial are required before more definitive conclusions can be made.
References 1 Stonebridge PA, Howlett R, Prescott R, Ruckley CV. Randomised trial comparing polytetrafluoroethylene graft patency with and without a Miller cuff. Br J Surg 1995; 82: 555±556. 2 Da Silva AF, Carpenter T, How TV, Harris PL. Stable vortices within vein cuffs inhibit anastomotic myointimal hyperplasia? Eur J Vasc Endovasc Surg 1997; 14: 157±163. 3 How TV, Rowe C, Gilling-Smith GL, Harris PL. Interposition vein cuff anastomosis alters wall shear stress distribution in recipient artery. J Vasc Surg 2000; 31: 1008±1018. 4 Zarins CK, Zatina MA, Giddens DP, Ku DN, Glagov S. Shear stress regulation of artery lumen diameter in experimental atherogenesis. J Vasc Surg 1987; 5: 413±420. 5 Sottiurai VS. Distal anastomotic intimal hyperplasia: histocytomorphology, pathophysiology, etiology and prevention. Int J Angiol 1999; 8: 1±10. 6 Pedersen EM, Oyre S, Agerbaek M et al. Distribution of early atherosclerotic lesions in the human abdominal aorta correlates with wall shear stresses measured in vivo. Eur J Vasc Endovasc Surg 1999; 18: 328±333. 7 Kraiss LW, Kirkman T, Kohler TR, Zierler B, Clowes AW. Shear stress regulates smooth muscle proliferation and neointimal thickening in porous polytetrafluoroethylene grafts. Arterioscler Thromb 1991; 11: 1844±1852. 8 Kohler TR, Kirkman T, Kraiss LW, Zierler B, Clowes AW. Increased blood flow inhibits neointimal hyperplasia in endothelialised vascular grafts. Circ Res 1991; 69: 1557±1565. 9 Fisher RK, Toonder I, Hoedt M, How TV, Brennan JA, Harris PL. Harnessing haemodynamics for the suppression of anastomotic intimal hyperplasia: the rationale for precuffed grafts. Eur J Vasc Endovasc Surg 2001; 21: 520±528. 10 Anonymous. Second European Consensus Document on Chronic Critical Limb Ischaemia. Eur J Vasc Surg 1992; 6(A): 1±32. 11 No authors listed. Management of Peripheral Arterial Disease (PAD). TransAtlantic Inter-Society Consensus (TASC). Section D: chronic critical limb ischaemia. Eur J Vasc Endovasc Surg 2000; 19(Suppl A): S144±S243. 12 Arfvidsson B, Lundgren F, Drott C, Schersten T, Lundholm K. Influence of coumarin treatment on patency and limb salvage after peripheral arterial reconstructive surgery. Am J Surg 1990; 159: 556±560. 13 Ktretschmer GJ, Holzenbein T, Huk I, Abela C. What is the evidence that anticoagulant treatment improves long-term patency of distal bypass? In: Greenhalgh RM, Fowkes FGR, eds. Trials and Tribulations of Vascular Surgery. Evidence Based Vascular Surgery. London: Saunders, 1996; 43±52. 14 Sarac TP, Huber T, Back MR et al. Warfarin improves the outcome of infrainguinal vein bypass grafting at high risk of failure. J Vasc Surg 1998; 28: 446±457.
The Distaflo Graft 15 da Silva AF, Desgranges P, Holdsworth J et al. The management of outcome of critical limb ischaemia in diabetic patients: results of a national survey: Audit Committee of the Vascular Surgical Society of Great Britain and Ireland. Diab Med 1996; 13: 726±728. 16 Enzler MA, Ruoss M, Seifert B, Berger M. The influence of gender on the outcome of arterial procedures in the lower extremity. Eur J Vasc Endovasc Surg 1996; 11: 446±452. 17 Jonsson B, Skau T. Outcome of symptomatic leg ischaemia: four year morbidity and mortality in Vadstena, Sweden. Eur J Vasc Endovasc Surg 1996; 11: 315±323. 18 Panneton J. Early results of North American randomised control trial of Distaflo versus interposition vein. In: Greenhalgh R, ed. Vascular and Endovascular Techniques. London: 23rd Charing Cross International Symposium, 2001. 19 Fisher RK, How TV, Carpenter T, Brennan JA, Harris PL. Optimising Miller cuff dimensions. The influence of geometry on
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anastomotic flow patterns. Eur J Vasc Endovasc Surg 2001; 21: 251±260. 20 Suggs WD, Henriques H, DePalma RG. Vein cuff interposition prevents juxta-anastomotic neointimal hyperplasia. Ann Surg 1988; 207: 717±723. 21 Veith FJ, Gupta SK, Ascer E, White-Flores S et al. Six-year prospective multicentre randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial constructions. J Vasc Surg 1986; 3: 104±114. 22 Tilanus HW, Obertop H, van Urk H. Saphenous vein or PTFE for femoropopliteal bypass. A prospective randomized trial. Ann Surg 1985; 202: 780±782.
Accepted 4 December 2002
Eur J Vasc Endovasc Surg Vol 25, March 2003