Indian Journal of Vascular and Endovascular Surgery

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 7  |  Issue : 4  |  Page : 351--355

Graft-related complications after open surgery of abdominal aortic aneurysm – An 8-year follow-up study


Vineeth Kumar1, Prakash Goura1, Sreekumar Ramachandran2, Unnikrishnan Madathipat3, Ashutosh Kumar Pandey1, Sriram Manchikanti1, Neelamjingbha Sun1, Shivanesan Pitchai1,  
1 Department of Cardiovascular and Thoracic Surgery, Division of Vascular Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
2 Department of General Surgery, Division of Vascular Surgery, Government Medical College, Thiruvananthapuram, Kerala, India
3 Division of Vascular Surgery, Sree Uthradam Tirunal Hospital, Thiruvananthapuram, Kerala, India

Correspondence Address:
Shivanesan Pitchai
Department of Cardiovascular and Thoracic Surgery, Division of Vascular Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala
India

Abstract

Introduction: Open surgery repair (OSR) is generally considered as a single definitive procedure and requires minimal postoperative follow-up once immediate survival is established. There are many studies which focus on endovascular aneurysm repair reintervention, only few contemporary studies report graft-related reinterventions after open repair. The present study describes the incidence of graft-related complications following OSR for abdominal aortic aneurysm (AAA) and its management. This study also analyse the factors which can preoperatively predict the occurrence of graft related complications, so that necessary steps can be taken to prevent such complications. Materials and Methods: This is a single-center prospective analysis of 165 patients who underwent elective open repair for AAA over a period of 8 years from January 2008 to December 2016. Demographics, preoperative, perioperative, and postoperative data were recorded in a structured data collection sheet after reviewing patient records and institutional electronic medical records after obtaining clearance from the Institutional Ethics Committee. Results: The overall incidence of graft-related complications in our study was 6.6%. The most common graft-related complication in our study is iliac graft limb occlusion 3.6% followed by graft infection of 1.5% and anastomotic pseudo aneurysm of 1.5%. The graft-related reintervention rate is 5.1% and graft-related mortality is 1.5% in 8-year follow-up. The risk factors for graft-related complications are preoperative uncontrolled DM, aorto-iliac aneurysms, use of bifurcated graft, and postoperative wound infection. Conclusions: This study showed that aggressive control of DM preoperatively and anastomosing distal Y-limb of graft to femoral artery rather than external iliac artery may decrease the complications. The majority of graft-related complications occurred 2 years after surgery. Hence, we suggest that those patients with above risk factors should be put on a short-interval surveillance program.



How to cite this article:
Kumar V, Goura P, Ramachandran S, Madathipat U, Pandey AK, Manchikanti S, Sun N, Pitchai S. Graft-related complications after open surgery of abdominal aortic aneurysm – An 8-year follow-up study.Indian J Vasc Endovasc Surg 2020;7:351-355


How to cite this URL:
Kumar V, Goura P, Ramachandran S, Madathipat U, Pandey AK, Manchikanti S, Sun N, Pitchai S. Graft-related complications after open surgery of abdominal aortic aneurysm – An 8-year follow-up study. Indian J Vasc Endovasc Surg [serial online] 2020 [cited 2021 Feb 28 ];7:351-355
Available from: https://www.indjvascsurg.org/text.asp?2020/7/4/351/304636


Full Text



 Introduction



In the current era of endovascular therapy, open surgery repair (OSR) of abdominal aortic aneurysm (AAA) is usually indicated in those who do not meet anatomical criteria for endovascular aneurysm repair (EVAR).[1] EVAR had inherent risks of endoleak which requires a strict follow-up protocol and reintervention for the same. However, OSR is generally considered as a single definitive procedure and requires minimal postoperative follow-up once immediate survival is established.

The present study describes the incidence of graft-related complications in OSR for AAA mainly graft thrombosis, graft infection, anastomotic aneurysm, anastomotic stenosis, and their management. This study also tries to find out the factors which can preoperatively predict the occurrence of graft-related complications after OSR so that necessary steps can be taken to avoid such complications.

 Materials and Methods



This is a single-center prospective analysis of 165 patients who underwent elective open repair for AAA over a period of 8 years from January 2008 to December 2016. Suprarenal, Type 4 thoraco AAA, ruptured AAA, and isolated iliac artery aneurysms are excluded from this study. Demographics, preoperative, perioperative, and postoperative data were recorded in a structured data collection sheet after reviewing patient records and institutional electronic medical records after obtaining clearance from the Institutional Ethics Committee. The main aim of the study is to find out the preoperative factors associated with occurrence of graft-related complications, effect on long-term survival, prevention, and management.

Statistical analysis

Statistical analysis was performed using the Chi-square test, Log-rank test, and Kaplan–Meyer Survival analysis. All data analysis was done using the Windows Excel 2010 and IBM SPSS Statistics for Windows, Version 25.0. (Armonk, NY: IBM Corp.).

 Results



Patient demographics

During the period of 8 years from 2008 to 2016, 165 patients underwent elective open surgical repair of AAAs. The mean age was 64.9 years in this male predominant cohort. Maximum follow-up was up to 90 months. The mean size of an aneurysm was 6.8 cm (range from 4.0 to 14 cm). The study cohort had 52% of patients with infrarenal AAA, 17.6% with juxtarenal AAA and combined infrarenal and common iliac artery (CIA) aneurysm in 33.1%. All patients underwent endoaneurysmoraphy with a tubular graft in 64% patients and bifurcated graft in 36% of patients. Other demographic factors are detailed in [Table 1].{Table 1}

Incidence, morbidity, and mortality related to graft-related complications

The overall incidence of graft-related complications in our study was 6.6% (n-13) [Figure 1]. The most common graft-related complication in our study is graft limb occlusion (3.6%, n-7) followed by graft infection (n-3) and anastomotic pseudo aneurysm (n-3) both having an equal incidence of 1.5%. None of the patients had aortoenteric or aortocaval fistula in our study. All the patients who developed graft limb occlusion occurred at the iliac anastomotic site of the bifurcated graft, majority of them presented with intermittent claudication of varying severity and all events happened after 2 years. Three patients had graft-related (1.5%) mortality in the study cohort. The first patient was a known case of Takayasu arteritis on oral steroids, presented with acute abdomen 4 years after surgery and on computed tomography (CT) imaging was found to have juxta-renal proximal anastomotic pseudoaneurysm (PSA) with a contained rupture, taken up for an emergency surgery, intraoperatively the aortic tissue was severely inflamed and aortic tissue was not holding even after felt and pledgeted stitch, expired intraoperatively due to massive hemorrhage and hypovolemic shock. The second patient had acute thrombosis of Y limb of the graft 6 years postoperative, presented with acute limb ischemia class 3; planned for emergency amputation, but developed acute pulmonary edema and succumbed to death. The third patient had graft infection 18 months after surgery, presented with Pyrexia of Unknown Origin; evaluated in the peripheral hospital and by the time patient reached our center was in septic shock, and later succumbed to death.{Figure 1}

Management and survival after graft-related complications

The graft related reintervention rate is 5.1% and graft-related mortality is 1.5% during 8 years follow-up. Among 13 patients who developed chronic graft-related complications, 8 underwent interventions. There were two patients who developed graft occlusion had only intermittent claudication not affecting daily activities, so was advised best medical management, two patients underwent crossover Femoro-femoral bypass grafting, another two patients underwent stenting for stenosis at the iliac anastomosis. Graft infections in two patients were managed by graft explanation and extra-anatomic bypass with a thoraco femoral bypass in one and the other with axillofemoral bypass. We had two patients with proximal anastomotic pseudo aneurysm and were treated by open repair [Figure 2]. The morbidity associated with graft-related interventions affected the overall survival of patients with graft-related complications as depicted in the Kaplan–Meier analysis [Figure 3]. The mean duration of survival for patients with graft-related complications even after successful intervention was 61.8 months (95% confidence interval 59.6–71.9) as compared to 83.5 months for patients without graft-related complications which was statistically significant (P = 0.05).{Figure 2}{Figure 3}

Risk factors for graft related complications

The risk factors for graft-related complications in our study are preoperative uncontrolled diabetes mellitus (DM), aorto-iliac aneurysms, use of bifurcated graft, and postoperative wound infection [Table 2]. There is statistically significant association (P < 0.001) with postoperative wound infections with long-term graft-related reinterventions. Nearly 50% of the patients with postoperative wound infection and 26% of patients with preoperative uncontrolled diabetes mellitus developed graft-related complications mainly in the form of graft infections. Those patients with aortoilliac aneurysms had a significant association (P = 0.03) with occurrence graft-related complications mainly anastomotic PSA. We found that there is a significant association between the use of bifurcated graft and graft-related complications (P = 0.001) and on further probing found that majority of them are graft occlusion, happened in those patients where distal anastomosis of Y graft was given to external iliac artery (EIA) rather than femoral artery.{Table 2}

 Discussion



Graft-related complications after OSR of AAA are infrequent but lethal in nature if not detected and managed in appropriate time. Society of vascular surgery recommends abdominal and pelvic CT imaging every 5 years after OSR.[2] Here, we give an overview of the graft-related complications, management, and its effect on overall survival. The two most common graft material used for open repair of AAA are Dacron and polytetrafluoroethylene (PTFE). Most of the in vivo studies in animal model showed a conflicting results regarding graft infection between Dacron and PTFE.[3],[4],[5] In vitro studies using a pulsatile perfusion system, indium-111 labelled bacteria was circulated through graft and gama count/graft were measured.[6] This was used to calculate the bacteria/cm2 of graft and found that PTFE had the least bacterial adherence when compared to Dacron and Human umbilical vein graft. The same study also showed that the suture line in a PTFE graft increased its bacterial adherence to 50%.

The overall incidence of graft-related complications in our study is 6.6%. Hallett study reported a 9.4% graft-related complication at an average follow-up of 5.8 years with surveillance imaging.[7] The follow-up protocol in our study is mainly clinical examination and ankle brachial index not with a fixed interval imaging surveillance. If the patient complains of any particular symptom, then only we insist on imaging with ultrasound. With this protocol, detection of graft-related complications is at par with various studies described. The graft-related complication may be much more if we have included ruptured aneurysms as in a similar study by Biancari et al. with a 15.4% late graft-related complication with a median follow-up of 15 years.[8]

The most common graft-related complication in our study is graft limb occlusion (3.6%), followed by anastomotic PSA (1.2%) and graft infections (1.2%). Isolated limb occlusion manifested with claudication, but occlusion of the entire graft presented with a/c limb ischemia. The most common cause of graft limb occlusion described in the literature is poor outflow in the form of peripheral occlusive arterial disease (POAD) in the distal target vessels, but in our study, we could not find any association between POAD and graft limb occlusion. One important finding noted in our study is that graft limb occlusion was more common in which distal anastomosis was done in EIA rather than femoral artery. The anastomosis to EIA was done in selected cases where we encountered technical difficulty in dissecting the CIA bifurcation. In such cases, we have given graft (end) to EIA (side) anastomosis along with ligation of the proximal iliac bifurcation so that the ipsilateral IIA will get retrograde flow from graft. Even though the preoperative CT may show good lumen in EIA, early atherosclerotic changes like increased intimo-medial thickening and speckled calcification may not be evident in CT. EIA being a conduit vessel with its on natural curve at iliac brim will get exposed to increased shear stress from the excess graft flow. This may cause an accelerated neointimal proliferation or atherosclerosis progression. Since the diameter of EIA is less compared to CIA or common femoral artery, the culprit lesion become flow limiting at an earlier stage. Moreover, majority of these patients with graft occlusion restarted their smoking habits few months after surgery even though preoperative smoking had no effect on the incidence of graft-related complications (P = 0.43).

Although graft infection is rare with an incidence of 0.3%, historically, it has been the indication for intervention in up to 25% of redoaortic surgery.[9] In patients presenting with minimal contamination, in situ reconstruction with femoral vein or cryopreserved allograft can be tried but in patients with gross contamination and hemodynamically instability extra-anatomic bypass is the only option.[9],[10],[11] Usually aortic graft infection presented on an average of 3 years or later after open repair, but endograft infection manifests at an earlier date for reasons that remain unclear.[12] In our study, majority of graft infection occurred within 2 years of follow-up and all of them were treated with extraanatomic bypass because of gross contamination and septic shock. We found that graft infection is closely associated with the problems of groin wound healing in the immediate postoperative period (P = 0.001). Literature says that femoral artery extension of a prosthesis increases the incidence of graft infection from 1% to 3%,[13] but in our study, we couldn't found any significant association between femoral extension and graft infection. The probable reasons were the uneven distribution of uncontrolled DM and predominance of tube graft usage in study population may serve as a risk factor and population bias, respectively.

Coming to paraanastomotic aneurysm, we should make a clear differentiation between true and pseudo/false aneurysms. A true para-anastomotic aneurysm means those developing adjacent to the anastomosis, whereas pseudo para-anastomotic aneurysms mean those aneurysms resulting from disruption of the anastomosis. However, this distinction of paraanastomotic aneurysms is not well defined in the majority of studies.[14] The patient in our study had paraanastomotic aneurysm post OSR because of Takayasu arteritis. The cause of paraanastomotic aneurysm in Takayasu arteritis is inflammation and associated vessel wall weakness. In a study in 103 patients of Takayasu's arteritis with 40 years follow-up, anastomotic aneurysm tended to occur irrespective of systemic inflammation or steroid administration.[15] In Takayasu arteritis, aneurysmal disease are frequently detected because patients are usually younger than atherosclerotic aneurysm so that they live longer.[16] In the era before CT imaging, Szilagyi et al. in his 15-year follow-up study noted that anastomoses at the femoral artery were at highest risk (3%), followed by the iliac artery (1.2%) and infrarenal aorta (0.2%) for anastomotic aneurysm.[17] This observation has been confirmed by others, particularly the risk of femoral PSA formation among patients treated with an aorto-bifemoral graft.[18] Similarly, in our study, the uses of bifurcated grafts intraoperatively for the repair of common iliac aneurysm have significant association with anstomotic pseudo aneurysm.(P = 0.01).

The major causes of death following AAA repair is myocardial infarction followed by cancer and pulmonary disease.[19] In our study, among 162 patients with a mean follow-up period of 8 years, the long-term mortality was 7.3%, and graft-related mortality was 1.8% patients The mean duration of survival for patients with graft-related complications was 61.8 months as compared to 83.5 months for patients without graft-related complications which indicates graft-related re-interventions affected the overall long-term survival of the patients.

 Conclusions



The morbidity and mortality following AAA surgeries improved over time, but the incidence of graft-related complications remains the same. Aggressive control of DM preoperatively and anastomosing distal Y-limb of graft to femoral artery rather than EIA may decrease these complications. Overall, long-term survival of the patient with graft-related complications are less when compared to those patients who had a normal postoperative recovery. The majority of graft-related complications occurred 2 years after surgery which is a subtle sign of disease progression. Hence, we suggest that those patients with above risk factors should be put on a short-interval surveillance program by noninvasive imaging for the early detection of complication before the onset of symptom complex.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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