General Review Update on the Role of the Distal Arteriovenous Fistula as an Adjunct for Improving Graft Patency and Limb Salvage Rates after Crural Revascularization Herbert Dardik, Englewood, New Jersey
Background: Critical ischemia of the lower limb continues to challenge the ingenuity of all interventionalists in achieving reliable, predictable, and durable patency. The objective of this study was to investigate the role of the distal arteriovenous fistula (dAVF) to enhance crural revascularization patency rates particularly when prosthetics are used. Methods: All patients who underwent crural bypass with dAVF since 1979 were included. Graft patency was assessed periodically by clinical examination and Doppler studies. Results were analyzed by life-table methodology to obtain primary and secondary patency rates and limb salvage rates. Results: A total of 502 crural bypass plus dAVF procedures were studied within 4 consecutive periods. Primary patency rates at 1 and 3 years for each of the 4 consecutive periods were (1) 36% and 10%, (2) 52% and 15%, (3) 54% and 31%, and (4) 70% and 46%. Corresponding secondary patency rates were (1) 43% and 17%, (2) 60% and 29%, (3) 60% and 44%, and (4) 72% and 50%. There was a statistically significant improvement for primary and secondary patency rates when comparing the last 2 periods with the first 2. Limb salvage rates also showed significant improvement for the same periods. Conclusions: Creation of a dAVF should be considered as a component of crural revascularization when prosthetics are used. The altered hemodynamics associated with dAVF prevents overload and as a consequence, potential bypass closure. The contribution of dAVF for enhancing patency rates when autologous vein is used with compromised runoff requires further study.
INTRODUCTION Paradigm shifts in the performance of vascular surgery have transformed the specialty and enabled rapid recovery, decreased morbidity, and
This study was supported in part by the Diane and James Perrella Foundation and the Douglas Francis Memorial Fund. Department of Vascular Surgery, Englewood Hospital and Medical Center, Englewood, NJ. Correspondence to: Herbert Dardik, MD, Department of Vascular Surgery, Englewood Hospital and Medical Center, 350 Engle Street, Englewood, NJ 07631, USA; E-mail: [email protected] Ann Vasc Surg 2015; 29: 1022–1028 http://dx.doi.org/10.1016/j.avsg.2015.02.003 Ó 2015 Elsevier Inc. All rights reserved. Manuscript received: November 18, 2014; manuscript accepted: February 18, 2015; published online: March 11, 2015.
1022
application to a larger population even with increased risk factors. It is vital that surgical procedures of any type prove durable, tolerable, and affordable. This update suggests that the creation of a distal arteriovenous fistula (dAVF) complimentary to crural reconstruction where a prosthetic is used can enable improved graft patency rates.
METHODS From November 1979 to December 2013, 502 dAVFs were constructed in 487 patients after obtaining informed consent. In that this investigation was initiated more than 35 years ago, institutional review board oversight was not available or obtained as the project matured and became a standard component of the procedures reported herein.
Vol. 29, No. 5, July 2015
Bilateral procedures were performed in 11 patients and repeat ipsilateral procedures in 4. The group consisted of 363 men and 124 women, aged 31e91 years (mean, 72 years). Demographics, risk factors, and prior ipsilateral procedures are summarized in Table I. Table II lists the indications for performing bypass plus dAVF. The procedures were analyzed within the 4 periods shown in Table III, recognizing the fact that these periods are variable in length and therefore detract from truly valid statistical analysis. These periods were based on previously published time schedules.1e3 In addition, 2 variations of the umbilical vein grafts were used during the specific times of their manufacture (Meadox Medicals, 1979e89 and Synovis [BioVascular], 1989e2007) and therefore contribute to the difficulty in creating exact and comparable periods. The current unreported cases (n ¼ 215) added to those cases from prior reports, provide a unique personal experience from which a number of conclusions can be reached2,4 The number of cases in each period is depicted in Table III and the types of graft materials used and the distribution of the target arteries. Indication The primary indication for creating an adjunctive dAVF is the use of a prosthetic graft that extends to any one of the crural arteries. If a borderline saphenous vein is used and whenever the runoff is poor or otherwise compromised, the use of a dAVF may also prove beneficial. Generalized contraindications for performing a dAVF include absence of any arterial runoff, undersized venous comitantes (smaller than the diameter of the crural artery), and a poor deep venous system such as phlebosclerosis and deep vein thrombosis. Venous sonography, although helpful for some cases, was not universally reliable to define this pathology, best determined at surgery. Technique The precise techniques have been previously described.2,5 Our current method for creating a dAVF has evolved from various configurations to the ‘‘common ostium’’ technique. Approximately 3 cm of the runoff artery and its dominant venous concomitant are mobilized. After placement of a tourniquet, parallel arteriotomy and venotomy incisions (2e2.5 centimeters) are placed at 10 o’clock and 2 o’clock corresponding positions. A side-toside posterior wall anastomosis of the artery to the vein is established with a continuous 7-0 polypropylene suture, the ends of which will be
Update on the role of the dAVF 1023
Table I. Patient demographics, risk factors, and prior procedures
Procedures Patients Mean age, range Male Risk factors Smoking Diabetes Hypertension Coronary artery disease End stage renal disease Hyperlipidemia Prior ipsilateral procedures Bypass Endovascular Inflow
N
%
502 487 72, 31e91 363
74.5
310 291 345 216 78 182
63.7 59.8 70.8 44.4 16.0 37.4
184 22 32
36.7 4.4 6.4
Table II. Indications for bypass surgery with dAVF (n ¼ 502) Indication
N
%
Disabling claudication Rest pain Focal neurosis/ulcer Pregangrene/gangrene Total
10 163 244 85 502
2.0 32.5 48.6 16.9 100
subsequently tied to one of the terminal interrupted sutures, proximally and distally. The actual anastomosis is initiated by placing 2 or 3 interrupted sutures at the heel between the artery and graft and vein and graft. The remainder of the anastomosis is completed using a continuous suture technique after tying the interrupted sutures, bringing the heel down first. A similar technique is used for the distal half of the anastomosis. The time required to perform a dAVF plus distal anastomosis ranges from 35 to 70 min (mean, 45 min) and is dependent on surgical skill and experience. The location of the fistula is restricted to the middle and distal thirds of the limb to any one of the crural vessels although exceptions are possible. After completion of the distal anastomosis, the graft is tunneled retrograde and the proximal anastomosis completed. Completion angiography and duplex sonography are performed routinely at the conclusion of the procedure. With open dAVFs, diastolic flow is high, consistent with low resistance. Despite high flow volumes into the venous circuit, distal perfusion can be noted on follow-up studies and confirmed by clinical outcome. Patients were
1024 Dardik
Annals of Vascular Surgery
Table III. Total dAVF experience (n ¼ 502)
Group
Reference
Study years
#Years
1 2 3 4 Totals
1 2 2 Present study
1979e83 4 1984e89 5 1990e95 5 1996e2013 17 31
Target arteries
Conduit
#dAVFs
Mean #dAVF/year
PT
AT
PER
UV
ASV
111 105 71 215 502
27.8 21.0 14.2 12.4 20.5
46 57 28 79
20 18 15 64
45 30 28 72
110 0 99 6 64 5 190 3 463 14
PTFE
D
NA
0 0 2 17 19
0 0 0 5 5
1 0 0 0 1
PT, posterior tibial artery; AT, anterior tibial artery; PER, peroneal artery; UV, umbilical vein graft; ASV, autologous saphenous vein graft; PTFE, polytetraflourethylene graft; D, polyester graft (Dacron); NA, native artery.
followed up clinically and with sonography at 4-month intervals after the postoperative period and increasing intervals after the first year (6e 8 months). Outcomes were documented using actuarial life tables constructed by the KaplaneMeier method.6 Statistical analysis was performed using SAS 9.4 software (Cary, NC). Survival rates were produced with KaplaneMeier survival curves with log-rank tests for comparisons between periods. A Bonferroni correction was used to adjust for family-wise error rates.
RESULTS This series of dAVFs as adjuncts to crural revascularization spans a period greater than 3 decades in which the technique was continuously modified. This evolving procedure in conjunction with recognition of indications and factors predictable for success or failure has resulted in outcomes that are distinctly superior for the 2 most recent periods compared with the first 2. This is depicted in the cumulative patency rates shown in Figure 1. Differences in some of the cumulative patency rates between current values and those in earlier publications for the same periods are based on a later review of the data which then included additional failures and withdrawn cases during these comparable periods. Primary crural bypass patency rates at 1 and 3 years over the 4 periods were (1) 36% and 10%, (2) 52% and 15%, (3) 54% and 31%, and (4) 70% and 46%. Secondary patency rates were (1) 43% and 17%, (2) 60% and 29%, (3) 60% and 44%, and (4) 72% and 50%. Differences between primary and secondary patencies for each period were insignificant. Secondary patency rates were statistically higher when comparing the periods 1990e1995 and 1996e2013 with the period 1979e1983 (Bonferroni corrected P values for the log-rank test are less than 0.001 for both comparisons). Likewise, secondary patency rates are statistically higher for the period 1996e2013 when compared with the time
period 1984e1989 (P value ¼ 0.002). Secondary patency rates over the period 1996e2013 were statistically higher than the previous period, 1990e 1995 (P value ¼ 0.043). No statistical differences exist when comparing secondary patency rates from 1984 to 1989 with those of 1979e1983 (P ¼ 0.114); likewise no statistically significant differences exist when comparing rates from 1984 to 1989 with those of 1990e1995 (P ¼ 0.576). Most importantly, the differences in patency outcomes for the final period were significantly improved compared with those of the earlier periods. Limb salvage rates at 1 and 3 years also showed significant improvement (P ¼ 0.002) for the last 2 periods compared with the first 2: (1) 70% and 44%, (2) 73% and 48%, (3) 81% and 75%, and (4) 86% and 72%. The number of cases per annum since the onset of our endovascular program has shown a steady decline with a corresponding decrease in creating dAVFs, 9.9 per year (2000e2013) compared with 19 per year in the period 1979e99. This progressive decrease in the number of dAVFs in each period is inversely related to the increasing use of infrageniculate endovascular procedures.
DISCUSSION Graft patency is inversely related to outflow resistance. High resistance results in flow rates that may be lower than the critical thrombotic threshold for the particular material used for bypass. A number of investigators have sought methods to improve graft patency rates when runoff is compromised. This includes the Taylor patch,7 Miller vein cuff,8 and St. Mary’s boot.9 Although local turbulence may be affected, flow dynamics are unaltered in the face of compromised runoff. Nguyen et al.10 recently confirmed that venous adjuncts did not improve acute prosthetic graft patency. Graft flow (volume and velocity) also exceeds the critical thrombotic threshold level when using
Vol. 29, No. 5, July 2015
Update on the role of the dAVF 1025
Fig. 1. Primary and secondary cumulative patency rates for crural bypasses plus dAVF based on four time periods. (A) 1979-83. (B) 1984-89. (C) 1990-95. (D) 1996-2013. There was progressive improvement in patency rates between the first and last time periods with a significant
difference (P
Background: Critical ischemia of the lower limb continues to challenge the ingenuity of all interventionalists in achieving reliable, predictable, and durable patency. The objective of this study was to investigate the role of the distal arteriovenous fistula (dAVF) to enhance crural revascularization patency rates particularly when prosthetics are used. Methods: All patients who underwent crural bypass with dAVF since 1979 were included. Graft patency was assessed periodically by clinical examination and Doppler studies. Results were analyzed by life-table methodology to obtain primary and secondary patency rates and limb salvage rates. Results: A total of 502 crural bypass plus dAVF procedures were studied within 4 consecutive periods. Primary patency rates at 1 and 3 years for each of the 4 consecutive periods were (1) 36% and 10%, (2) 52% and 15%, (3) 54% and 31%, and (4) 70% and 46%. Corresponding secondary patency rates were (1) 43% and 17%, (2) 60% and 29%, (3) 60% and 44%, and (4) 72% and 50%. There was a statistically significant improvement for primary and secondary patency rates when comparing the last 2 periods with the first 2. Limb salvage rates also showed significant improvement for the same periods. Conclusions: Creation of a dAVF should be considered as a component of crural revascularization when prosthetics are used. The altered hemodynamics associated with dAVF prevents overload and as a consequence, potential bypass closure. The contribution of dAVF for enhancing patency rates when autologous vein is used with compromised runoff requires further study.
INTRODUCTION Paradigm shifts in the performance of vascular surgery have transformed the specialty and enabled rapid recovery, decreased morbidity, and
This study was supported in part by the Diane and James Perrella Foundation and the Douglas Francis Memorial Fund. Department of Vascular Surgery, Englewood Hospital and Medical Center, Englewood, NJ. Correspondence to: Herbert Dardik, MD, Department of Vascular Surgery, Englewood Hospital and Medical Center, 350 Engle Street, Englewood, NJ 07631, USA; E-mail: [email protected] Ann Vasc Surg 2015; 29: 1022–1028 http://dx.doi.org/10.1016/j.avsg.2015.02.003 Ó 2015 Elsevier Inc. All rights reserved. Manuscript received: November 18, 2014; manuscript accepted: February 18, 2015; published online: March 11, 2015.
1022
application to a larger population even with increased risk factors. It is vital that surgical procedures of any type prove durable, tolerable, and affordable. This update suggests that the creation of a distal arteriovenous fistula (dAVF) complimentary to crural reconstruction where a prosthetic is used can enable improved graft patency rates.
METHODS From November 1979 to December 2013, 502 dAVFs were constructed in 487 patients after obtaining informed consent. In that this investigation was initiated more than 35 years ago, institutional review board oversight was not available or obtained as the project matured and became a standard component of the procedures reported herein.
Vol. 29, No. 5, July 2015
Bilateral procedures were performed in 11 patients and repeat ipsilateral procedures in 4. The group consisted of 363 men and 124 women, aged 31e91 years (mean, 72 years). Demographics, risk factors, and prior ipsilateral procedures are summarized in Table I. Table II lists the indications for performing bypass plus dAVF. The procedures were analyzed within the 4 periods shown in Table III, recognizing the fact that these periods are variable in length and therefore detract from truly valid statistical analysis. These periods were based on previously published time schedules.1e3 In addition, 2 variations of the umbilical vein grafts were used during the specific times of their manufacture (Meadox Medicals, 1979e89 and Synovis [BioVascular], 1989e2007) and therefore contribute to the difficulty in creating exact and comparable periods. The current unreported cases (n ¼ 215) added to those cases from prior reports, provide a unique personal experience from which a number of conclusions can be reached2,4 The number of cases in each period is depicted in Table III and the types of graft materials used and the distribution of the target arteries. Indication The primary indication for creating an adjunctive dAVF is the use of a prosthetic graft that extends to any one of the crural arteries. If a borderline saphenous vein is used and whenever the runoff is poor or otherwise compromised, the use of a dAVF may also prove beneficial. Generalized contraindications for performing a dAVF include absence of any arterial runoff, undersized venous comitantes (smaller than the diameter of the crural artery), and a poor deep venous system such as phlebosclerosis and deep vein thrombosis. Venous sonography, although helpful for some cases, was not universally reliable to define this pathology, best determined at surgery. Technique The precise techniques have been previously described.2,5 Our current method for creating a dAVF has evolved from various configurations to the ‘‘common ostium’’ technique. Approximately 3 cm of the runoff artery and its dominant venous concomitant are mobilized. After placement of a tourniquet, parallel arteriotomy and venotomy incisions (2e2.5 centimeters) are placed at 10 o’clock and 2 o’clock corresponding positions. A side-toside posterior wall anastomosis of the artery to the vein is established with a continuous 7-0 polypropylene suture, the ends of which will be
Update on the role of the dAVF 1023
Table I. Patient demographics, risk factors, and prior procedures
Procedures Patients Mean age, range Male Risk factors Smoking Diabetes Hypertension Coronary artery disease End stage renal disease Hyperlipidemia Prior ipsilateral procedures Bypass Endovascular Inflow
N
%
502 487 72, 31e91 363
74.5
310 291 345 216 78 182
63.7 59.8 70.8 44.4 16.0 37.4
184 22 32
36.7 4.4 6.4
Table II. Indications for bypass surgery with dAVF (n ¼ 502) Indication
N
%
Disabling claudication Rest pain Focal neurosis/ulcer Pregangrene/gangrene Total
10 163 244 85 502
2.0 32.5 48.6 16.9 100
subsequently tied to one of the terminal interrupted sutures, proximally and distally. The actual anastomosis is initiated by placing 2 or 3 interrupted sutures at the heel between the artery and graft and vein and graft. The remainder of the anastomosis is completed using a continuous suture technique after tying the interrupted sutures, bringing the heel down first. A similar technique is used for the distal half of the anastomosis. The time required to perform a dAVF plus distal anastomosis ranges from 35 to 70 min (mean, 45 min) and is dependent on surgical skill and experience. The location of the fistula is restricted to the middle and distal thirds of the limb to any one of the crural vessels although exceptions are possible. After completion of the distal anastomosis, the graft is tunneled retrograde and the proximal anastomosis completed. Completion angiography and duplex sonography are performed routinely at the conclusion of the procedure. With open dAVFs, diastolic flow is high, consistent with low resistance. Despite high flow volumes into the venous circuit, distal perfusion can be noted on follow-up studies and confirmed by clinical outcome. Patients were
1024 Dardik
Annals of Vascular Surgery
Table III. Total dAVF experience (n ¼ 502)
Group
Reference
Study years
#Years
1 2 3 4 Totals
1 2 2 Present study
1979e83 4 1984e89 5 1990e95 5 1996e2013 17 31
Target arteries
Conduit
#dAVFs
Mean #dAVF/year
PT
AT
PER
UV
ASV
111 105 71 215 502
27.8 21.0 14.2 12.4 20.5
46 57 28 79
20 18 15 64
45 30 28 72
110 0 99 6 64 5 190 3 463 14
PTFE
D
NA
0 0 2 17 19
0 0 0 5 5
1 0 0 0 1
PT, posterior tibial artery; AT, anterior tibial artery; PER, peroneal artery; UV, umbilical vein graft; ASV, autologous saphenous vein graft; PTFE, polytetraflourethylene graft; D, polyester graft (Dacron); NA, native artery.
followed up clinically and with sonography at 4-month intervals after the postoperative period and increasing intervals after the first year (6e 8 months). Outcomes were documented using actuarial life tables constructed by the KaplaneMeier method.6 Statistical analysis was performed using SAS 9.4 software (Cary, NC). Survival rates were produced with KaplaneMeier survival curves with log-rank tests for comparisons between periods. A Bonferroni correction was used to adjust for family-wise error rates.
RESULTS This series of dAVFs as adjuncts to crural revascularization spans a period greater than 3 decades in which the technique was continuously modified. This evolving procedure in conjunction with recognition of indications and factors predictable for success or failure has resulted in outcomes that are distinctly superior for the 2 most recent periods compared with the first 2. This is depicted in the cumulative patency rates shown in Figure 1. Differences in some of the cumulative patency rates between current values and those in earlier publications for the same periods are based on a later review of the data which then included additional failures and withdrawn cases during these comparable periods. Primary crural bypass patency rates at 1 and 3 years over the 4 periods were (1) 36% and 10%, (2) 52% and 15%, (3) 54% and 31%, and (4) 70% and 46%. Secondary patency rates were (1) 43% and 17%, (2) 60% and 29%, (3) 60% and 44%, and (4) 72% and 50%. Differences between primary and secondary patencies for each period were insignificant. Secondary patency rates were statistically higher when comparing the periods 1990e1995 and 1996e2013 with the period 1979e1983 (Bonferroni corrected P values for the log-rank test are less than 0.001 for both comparisons). Likewise, secondary patency rates are statistically higher for the period 1996e2013 when compared with the time
period 1984e1989 (P value ¼ 0.002). Secondary patency rates over the period 1996e2013 were statistically higher than the previous period, 1990e 1995 (P value ¼ 0.043). No statistical differences exist when comparing secondary patency rates from 1984 to 1989 with those of 1979e1983 (P ¼ 0.114); likewise no statistically significant differences exist when comparing rates from 1984 to 1989 with those of 1990e1995 (P ¼ 0.576). Most importantly, the differences in patency outcomes for the final period were significantly improved compared with those of the earlier periods. Limb salvage rates at 1 and 3 years also showed significant improvement (P ¼ 0.002) for the last 2 periods compared with the first 2: (1) 70% and 44%, (2) 73% and 48%, (3) 81% and 75%, and (4) 86% and 72%. The number of cases per annum since the onset of our endovascular program has shown a steady decline with a corresponding decrease in creating dAVFs, 9.9 per year (2000e2013) compared with 19 per year in the period 1979e99. This progressive decrease in the number of dAVFs in each period is inversely related to the increasing use of infrageniculate endovascular procedures.
DISCUSSION Graft patency is inversely related to outflow resistance. High resistance results in flow rates that may be lower than the critical thrombotic threshold for the particular material used for bypass. A number of investigators have sought methods to improve graft patency rates when runoff is compromised. This includes the Taylor patch,7 Miller vein cuff,8 and St. Mary’s boot.9 Although local turbulence may be affected, flow dynamics are unaltered in the face of compromised runoff. Nguyen et al.10 recently confirmed that venous adjuncts did not improve acute prosthetic graft patency. Graft flow (volume and velocity) also exceeds the critical thrombotic threshold level when using
Vol. 29, No. 5, July 2015
Update on the role of the dAVF 1025
Fig. 1. Primary and secondary cumulative patency rates for crural bypasses plus dAVF based on four time periods. (A) 1979-83. (B) 1984-89. (C) 1990-95. (D) 1996-2013. There was progressive improvement in patency rates between the first and last time periods with a significant
difference (P
