|Year : 2021 | Volume
| Issue : 3 | Page : 222-227
Graft patency and determinants of outcome in infrainguinal bypasses - A retrospective study
Sunil Rajendran1, Sreekumar Ramachandran2, P Sankara Sarma3, Madathipat Unnikrishnan4
1 Department of Vascular Surgery, Starcare Hospital, Kozhikode; Division of Vascular Surgery, Sree Chitra Tirunal Institute of Medical Science and Technology, Thiruvanthapuram, Kerala, India
2 Department of Surgery, Medical College; Division of Vascular Surgery, Sree Chitra Tirunal Institute of Medical Science and Technology, Thiruvanthapuram, Kerala, India
3 Achutha Menon Centre for Health Science Studies, Sree Chitra Tirunal Institute of Medical Science and Technology, Thiruvanthapuram, Kerala, India
4 Department of Vascular Surgery, SUT Hospital; Division of Vascular Surgery, Sree Chitra Tirunal Institute of Medical Science and Technology, Thiruvanthapuram, Kerala, India
|Date of Submission||12-Aug-2020|
|Date of Acceptance||29-Aug-2020|
|Date of Web Publication||6-Jul-2021|
Department of Vascular Surgery, SUT Hospital; Division of Vascular Surgery, Sree Chitra Tirunal Institute of Medical Science and Technology, Thiruvanthapuram, Kerala
Source of Support: None, Conflict of Interest: None
Context: Chronic lower limb ischemia, an important marker of atherosclerosis, is a common clinical problem prevalent in all socioeconomic groups in our country and across the globe. Infrainguinal bypass is mandated in a subset of patients with critical limb ischemia to provide immediate limb salvage as well as excellent long-term results. Aim: The purpose of our retrospective study is to elucidate the effect of various known factors on the long term patency of infrainguinal bypass grafts performed in our patient population at a tertiary referral hospital. Methods: We retrospectively reviewed follow up data of 110 patients who had undergone infrainguinal bypass grafting over a period of ten years in our Institutional vascular registry. Graft patency rates and factors affecting thereof over this period were studied and the data statistically analysed. Overall cumulative patency rates were calculated by the life table survival method and compared with that of the patency rates of above-knee bypass procedures in the world literature. Patency rates in a different subset of patients were calculated and compared using the Wilcoxon (Gehan) test and Fisher's exact test to assess the influence of various factors in the long term outcome of the procedure. Results: Cumulative patency in terms of graft survival probabilities based on the life table analysis was 0.84, 0.80, and 0.64 at 30, 60, and 90 months respectively. Grafts in patients who had continued to smoke post-operatively had failed when compared with those who did not smoke (P = 0.01). Cumulative patency rates of non- diabetics were higher as compared to non-diabetics (0.70 vs 0.44; P = 0.04). Conclusion: Our study shows that continued smoking and diabetes are the determinant factors associated with graft occlusion. Strict avoidance of smoking and optimal control of diabetes is likely to improve graft function and long-term patency in patients undergoing infra-inguinal bypass grafting.
Keywords: Chronic critical limb ischemia, cumulative patency, graft patency, infrainguinal bypass graft
|How to cite this article:|
Rajendran S, Ramachandran S, Sarma P S, Unnikrishnan M. Graft patency and determinants of outcome in infrainguinal bypasses - A retrospective study. Indian J Vasc Endovasc Surg 2021;8:222-7
|How to cite this URL:|
Rajendran S, Ramachandran S, Sarma P S, Unnikrishnan M. Graft patency and determinants of outcome in infrainguinal bypasses - A retrospective study. Indian J Vasc Endovasc Surg [serial online] 2021 [cited 2021 Jul 26];8:222-7. Available from: https://www.indjvascsurg.org/text.asp?2021/8/3/222/320614
| Introduction|| |
Chronic limb ischemia is a common problem, the prevalence of which is escalating with increasing age., Rest pain, tissue loss, impending gangrene, and disabling intermittent claudication are proven indications for attempting intervention to achieve limb salvage. In spite of the widespread use of endovascular therapy, surgical reconstruction is still the gold standard in critical limb ischemia due to long segment femoropopliteal occlusive disease. Apart from graft selection and type of procedure, long-term patency rates of these bypasses may be influenced by several patient factors. The purpose of this retrospective study was to determine the effect of age, smoking, diabetes, hypertension, and dyslipidemia on the cumulative patency rates of infrainguinal reconstructions in our population.
| Methods|| |
The follow-up data of all patients undergoing infrainguinal bypass grafts done at the division of Vascular Surgery at Sree Chitra Tirunal Institute of Medical Science and Technology, Trivandrum, Kerala, India, by the senior author from 1993 to 2003 were reviewed.
All patients were preoperatively evaluated and screened for risk factors such as smoking, diabetes, hypertension, dyslipidemia, and coronary artery disease. They were subjected to a preoperative angiography by a protocol set by our radiologists that included selective catheterization, delayed filming, and the use of intra-arterial vasodilators whenever needed. A decision regarding type of revascularization procedure to be employed was taken at a combined meeting of vascular surgeons and interventional radiologists.
Standard techniques were used to achieve infrainguinal bypass graft. The principal features included the use of meticulous vein harvest technique and gentle distension of the vein with heparinized saline. Anatomic tunneling was done and it was aimed to perform the proximal anastomoses to the common femoral artery but other sites such as superficial femoral artery and profunda femoris artery were also chosen when this was not available. Adjunct patch profondoplasty was performed using either vein or prosthesis after disobliterating the femoral bifurcation was done at the discretion of the operating surgeon. Distal anastomoses were done in most cases to above-knee popliteal artery but when this was not possible, other sites such as below-knee popliteal artery anterior tibial artery and posterior tibial arteries were chosen.
Saphenous vein was the conduit of choice over prosthetic grafts whenever possible. In all except eight patients, autologous great saphenous vein harvested from the patient's ipsilateral lower extremity was used. Prosthetic graft reconstruction was done in four patients in view of poor quality or nonavailability of an autologous vein and in another three for the want of shorter operating time due to coronary artery disease. Only one patient of the whole group needed a composite grafting. Prosthetic grafts were exclusively used only in cases where distal anastomosis was to the above-knee popliteal artery.
Objective assessment of technical adequacy was done using duplex evaluation before discharge. All cases were followed up initially 3 monthly and then yearly. Follow-up data consisted of physical examination and duplex scan assessment. Clinical evaluation included patency of the graft and other co-morbid health factors. History regarding the occurrence of new illnesses such as diabetes, hypertension, and the use of tobacco or abuse of alcohol and any episode of myocardial or cerebral events were also carefully recorded. Mention about the need for amputation and time frame when it was necessitated was noted. Femoral, popliteal, anterior, and posterior tibial arterial pulses were meticulously palpated and recorded. Blood pressure was recorded in the upper limb and lower limbs to measure the ankle-brachial index, to assess circulation in the lower limbs with reasonable accuracy. Patency was defined as presence palpable pedal pulses, an increase in ankle-brachial pressure index of > 0.15 from preoperative values, and/or demonstration of graft flow by the duplex scan. In addition to the objective evaluation of the bypass patency, the functional status of the limb was staged by the Fontaine stage.
In addition to calculating cumulative graft patency rates by the life table method, the bypass grafts were classified according to the possible factors affecting a long-term graft patency. Factors examined were the nature of graft material, level of distal anastomosis, patient age, diabetes, hypertension, dyslipidemia, and smoking. Cumulative patency rates of two groups in relation to the above-mentioned factors were compared using the Wilcoxon (Gehan) statistic survival variable test. The effect of postoperative smoking on patency rates was evaluated using Fisher's exact test.
| Results|| |
One hundred and ten infra-inguinal arterial reconstructions were performed during the study period for occlusive vascular diseases. Four patients had undergone bilateral grafting; one patient in the same sitting and the other three at different sittings. There was no operative mortality. Of 110 patients, 25 patients were lost to follow-up and only 85 cases with 90 grafts were available for complete follow-up. The duration of follow-up ranged from 6 to 139 months with a mean (standard deviation [SD]) of 56.8 (42.7). Sixteen patients had died due to various causes during follow-up, including 12, due to coronary artery disease and were excluded from the study group. Remaining 71 patients with 75 grafts were available for complete follow-up [Table 1].
The age of patients ranged from 30 to 82 years with a mean (SD) age of 54.2 (13.1) years of which 57.3% of patients were of more than 50 years of age. Sixty-six patients were males and only 5 patients were females making this a male predominant study. About 20% patients were smokers, 32% were hypertensive (Blood pressure >140/90 mm Hg), 20% patients were diabetic (fasting blood sugar >110 mg%), and 52% patients had hyperlipidemia (low-density lipoprotein [LDL] >130 mg%).
Proximal anastomoses were done to the common femoral artery in most cases (77%), followed by the superficial femoral artery (17.3%) and profunda femoris artery (6.7%). Distal anastomoses were done in most cases to above-knee popliteal artery (74.6%), other sites being below-knee popliteal artery (20%), anterior tibial artery (4%), and posterior tibial artery (1.3%).
Out of the 75 grafts available for follow-up, clinically patent reconstruction was evident in 45 patients. The duplex scan showed patency in further 12 patients to confirm successful grafting in 57 patients (76%). Angiogram was done to assess graft patency only when there was some discrepancy between clinical and duplex findings.
We could identify failing grafts in 5 patients by duplex surveillance. Two patients underwent thrombolysis while 2 others underwent balloon angioplasty in addition to thrombolysis to obtain assisted primary patency. One patient underwent inflow improvement in the form of aortofemoral graft procedure after failed thrombolysis and balloon angioplasty to reinstate graft flow. Subsequently, all these patients were maintained on both oral anticoagulant and antiplatelet medications. On further follow-up four of these patients had continued functioning grafts with good long-term outcome. There were 14 limbs with blocked conduits at the end of the study. Another four limbs needed to be amputated of which two required amputation within 1 year and the other two 5 years after the bypass procedure.
Ten patients of the 18 in the graft failure group had either Fontaine II claudication pain with significantly improved pain-free walking distance and had a good quality of life. Of the remaining 8, apart from four limbs that were amputated, the other four had nondisabling claudication needing medications. Hence, actual limb salvage was possible in 71 (94.6%) and improved functional recovery was achieved in 67 (89.3%) patients Overall cumulative patency rates at 12 months, 30 months, 60 months were 84.8%, 80.8%, and 65.4%, respectively [Figure 1] and [Table 2].
|Table 2: Life table cumulative bypass graft performance of all limbs included in this study|
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In this study, overall no statistically significant difference was noted in the cumulative patency rates when either prosthesis or autologous vein was used (P = 0.07) as a conduit for bypass and similarly the patency rate of grafts placed to the proximal popliteal artery, above the knee when compared with below the knee reconstructions (P = 0.763) did not reveal any significant difference in the outcomes since vein was the exclusive conduit for infragenicular reconstructions. When patient factors were considered, no statistically significant difference was noted in the outcome between patients less than or more than 50 years of age (P = 0.78). Nondiabetic individuals did fare much better than those with diabetes (P = 0.04) [Figure 2]. However, the presence of hypertension, dyslipidemia, and preoperative smoking did not seem to adversely affect the cumulative patency rates (P = NS) as summarized in [Table 3]. Of five patients who smoked postoperatively four had failed grafts during follow-up. Patency rates in this subset of patients were alarmingly low when compared to those who did not smoke after surgery (P = 0.01).
|Figure 2: Comparison of cumulative patency rates among patients with and without diabetes|
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|Table 3: Comparison of life table analysis of various factors affecting graft patency rates|
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| Discussion|| |
Infrainguinal bypass procedure is often mandated in patients with critical limb ischemia and higher TASC lesions, either refractory to medical management or unsuitable for interventional procedures. Nearly all these patients have limb-threatening ischemia with risk of imminent amputation if not revascularized expeditiously. Continued graft function is the key to successful outcome in patients. It is generally agreed that early graft function is mainly determined by right selection of the procedure and proper and tidy surgical techniques. However, long-term graft patency is influenced by numerous factors other than the factors leading to early graft failure. Cumulative patency rates of 84% at 30 months and 80% at 60 months and 64% at 120 months were comparable with numerous larger studies reported in English literature.,, In our study, an effort has been made to elucidate factors, which adversely affected the patency of the infrainguinal bypass procedures. Patient-related; graft-related as well as procedure-related factors were analyzed.
Type of conduit
In our study, vein was used as the preferred conduit whenever possible and prosthesis was opted for only when vein was unavailable or when the duration of the procedure needed to be reduced. Prosthesis was used only in 12% cases and in all these cases distal anastomoses were placed on the above-knee popliteal artery. Even though numbers in prosthetic graft group were small; we tried to compare the overall cumulative patency rates of all venous grafts with prosthetic graft used for above knee reconstructions. There was no statistically significant difference in cumulative patency rates between two groups. Similar results were reported by Ballotta et al. and Burger et al. in patients treated for disabling claudication., Ziegler et al. in a 20-year review reported better overall patency rates with autogenous vein grafts in all infrainguinal bypasses at all levels, however, Ambler et al. in a recent Cochrane review concluded that in patients who underwent infragenicular bypasses there is no clear evidence to suggest that patency of prosthetic grafts were inferior to vein bypasses to the below knee popliteal segments.,
Level of distal anastomosis
In general, patency rates of infrainguinal bypasses to above knee popliteal artery are superior to those with distal anastomosis to below the knee in view of shorter length, larger diameter and more importantly conduit not having to cross the knee joint. This holds particularly true for prosthetic grafts but not for vein grafts.,, In our study, 10 years' cumulative patency of bypasses using both vein and prosthetic grafts to above knee popliteal artery when compared with vein bypasses to below knee popliteal artery were 66% and 62%, respectively. Like in our study, Rosenthal and Woratyla et al. reported similar patency in an analysis comparing overall patency of all types of grafts used for supragenicular bypasses with vein only infragenicular bypasses.,
Not many studies have analyzed effect of patient factors on the outcome of infrainguinal bypass grafting. Younger age, hypertension, undetected diabetes mellitus, and continued smoking are noted to have detrimental effects on graft patency. All these factors are pro-atherosclerotic especially in combination.
Reed and associates had reported better outcome in patients aged more than 50 years undergoing aortofemoral grafting. This was attributed to increased incidence of smoking, presence of extensive atherosclerotic load and more progressive infrainguinal disease in younger patients. The same reasoning may also hold good for surgery for infrainguinal occlusive arterial disease as concluded by Mingoli et al. in a study of 228 cases undergoing crossover femorofemoral bypass grafting. However, our study reaffirms the findings of Barry et al., that no statistically difference was noted between patients less than or more than 50 years of age in terms of cumulative patency rates.
Continued smoking is the most critical factor leading to graft occlusion in most reported studies. Willigendael et al. in a meta-analysis reported a 3.09-fold increased incidence of graft failure in patients who continued smoking after a limb bypass surgery. In this study, patients were routinely counseled to stop smoking 6 weeks prior to the surgery. Five patients in this study, however, continued to smoke after surgery of which 4 patients developed graft thrombosis during the follow-up. Unlike other studies, we had only a small number of patients who continued to smoke as against those who refrained from smoking after the procedure (5 vs. 70), and hence a statistical comparison was not done. However, it seems very likely that postoperative smoking does have an adverse effect on graft patency, which needs to be validated in a larger study. Authors in the above meta-analysis further concluded that cessation of smoking after surgery restored graft patency rates similar to nonsmokers. Similarly, in this study, the difference in patency rates in patients who had stopped smoking in the postoperative period when compared with patency in nonsmokers was not statistically significant.
Peripheral arterial disease twice more common and has a more aggressive large vessel involvement when compared to nondiabetics. Wölfle et al. in a multicenter comparative analysis of short-term outcome of diabetes on patency rates of infrainguinal bypass in patients followed up for 1 year, reported similar patency rates among diabetics and nondiabetics. Rutherford et al. in a 3-year follow-up study concluded that diabetics patients undergoing infrainguinal bypass fared better than nondiabetics. Authors however attributed this to more use of vein grafts and lesser smoking in this group. Akbari et al. and Bellota et al. reported statistically similar 5-year primary patency of 75.6% and 65% in diabetics and 71.9% and 69.5% in nondiabetic invididuals., Bellota et al. in a Kaplan–Meier life-table analysis further reported a 10-year primary patency of 46% and 57% (P = 0.09). Contrary to this, in our study, 10-year cumulative patency rates were markedly different between diabetics and nondiabetics (44% vs. 70%) and were statistically significant (P = 0.04). Apart from postoperative smoking, this was the only factor that did adversely affect the final outcome of infrainguinal bypasses. Short-term cumulative patency rates appear to be satisfactory in diabetics but there seems to be an unfavorable outcome in terms of graft function beyond 5 years. This may be probably due to suboptimal control of blood sugars in our patient population due to limited access to specialized diabetic care.
There is convincing evidence between peripheral arterial disease and hypertension but its relations with hyperlipidemia is controversial. Not many studies have proven the role of these factors in graft failure. Lam et al. did conclude that hypertension was an independent risk factor for decreased graft patency but in this study we could not demonstrate any such association. Similarly, though experimental evidence suggest a positive relationship between increased cholesterol levels and failure of venous grafts, association has not been convincingly proven in clinical studies. There is no convincing difference in 10-year cumulative patency rates when patients with LDL levels > 130 mg/dl were compared with those with lower LDL levels in our series. Nevertheless, it has been categorically proven that control of these comorbid factors using ACE inhibitors and statins is associated with lower mortality, improved graft patency, and limb salvage.,
| Conclusion|| |
The present study deals with the factors affecting patency of infrainguinal grafting with more emphasis on the influence of patient factors. We conclude that infrainguinal bypass grafting is an important limb saving procedure in management of critical limb ischemia. We conclude that Infrainguinal bypass grafting is an important limb saving procedure in management of critical limb ischemia with excellent limb salvage rates and durable results. Results in our patient population are comparable with those in world literature. Optimization of patient factors is as important as performing the right surgery and choosing the best conduit while performing infrainguinal bypass grafting. Control of diabetes as well as strict avoidance of smoking are likely to improve graft function and long-term patency in patients undergoing infrainguinal bypass procedure.
Authors greatly acknowledge support by successive directors and other colleagues at Sree Chitra Tirunal Institute of Medical Sciences and Technology, Trivandrum, Kerala, India, for conduct of this study.
Financial support and sponsorship
This work was funded in part by Kerala Council for Science, Technology and Environment (KCSTE), Thiruvanthapuram. Kerala, India.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]