Dealing with Complications of Vascular Access Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 DOI: 10.1159/000365912
Safety Issues in Surgical and Endovascular Techniques to Rescue Failing or Failed Arteriovenous Fistulas and Arteriovenous Grafts Miltos Lazarides George Georgiadis Christos Argyriou Department of Vascular Surgery, Democritus University Hospital, Alexandroupolis, Greece
Abstract A great variety of thrombotic and nonthrombotic events may complicate all types of vascular access (VA) procedures. Thrombotic events are the most frequent complication, caused by stenoses in various locations, representing a common problem for arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs). Monitoring AVF with physical examination by trained physicians represents an accurate method for diagnosis of malfunction. AVF stenoses >50% in diameter should be treated either by surgical or endovascular means when accompanied with access malfunction. Aneurysms and infections represent the most frequent nonthrombotic VA complications. Access-related aneurysms do not represent per se an indication for intervention; however, anastomotic aneurysms and those with skin erosion should be repaired urgently to avoid rupture. Infections of AVFs are extremely rare, while AVG could be complicated either with postoperative infections attributable to the initial procedure with an early onset and more frequently with late infections caused by punctures, with an annual rate of 5%. Treatment options for AVG infections comprise total or subtotal graft excision or partial excision of the involved segment only, the latter representing a VA salvage procedure but with a significantly higher © 2015 S. Karger AG, Basel risk of recurrence.
• Check after creation of an arteriovenous fistula or arteriovenous graft (AVG) for palpable thrill or a bruit: The presence of a strong pulse in the draining vein without a thrill or bruit indicates a proximal venous stenosis. Patients need an instruction when checking their vascular access (VA) daily for bruit and thrill.
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Recommendations to Improve Patient Safety
• Failed or failing VA needs revision by surgical or endovascular means depending on the location of the lesion. Check thrombosed accesses after thrombectomy for underlying stenotic lesions that have to be corrected. • Anastomotic aneurysms and those with skin erosion (mostly false aneurysm of AVG) should be repaired urgently to avoid rupture and life-threatening hemorrhage. Patients should be informed about this complication. • Aneurysms are often associated with proximal stenosis, and this should be corrected simultaneously. • The best policy to prevent infection is to limit the implantation of synthetic prostheses only to patients with no autogenous options.
Introduction
The failure of vascular access (VA) represents the major cause of morbidity for those end-stage renal disease patients on hemodialysis, and access maintenance is the most frequent cause of hospitalization for such patients [1]. The subsequent extended length of stay commonly encountered in older patients is also related to further adverse events as hospital-acquired infections and fever, prolonged catheterization predisposing to central venous obstruction and delay in access revision with increased associated costs. The VA maintenance cost increases 5-fold for those patients with a failed autogenous access [2]. A great variety of thrombotic and nonthrombotic events may complicate all types of VA procedures and necessitate a wide spectrum of rescue operations.
Thrombotic events represent the most frequent complication of all VA with an incidence rate of 0.2/patient/year for arteriovenous fistula (AVF) and 0.8/patient/year for synthetic arteriovenous graft (AVG) [3]. Therefore, redo surgery is the rule rather than exception in VA patients. Stenosis is a common problem for AVFs and AVGs and represents the main cause of dysfunction and thrombosis, and the choice of the best method for repair depends on the location of the lesion. Access stenosis has been classified based on its location as: juxta-anastomotic (type I), in the cannulable segment (type II) and at the outflow into the deep venous system (type III) [4] (fig. 1). There are two additional categories of stenoses not involving the access itself, those of the central veins caused by longstanding catheters and those of the arterial inflow [5].
154
Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
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Stenoses and Thrombosis in Arteriovenous Fistulas or Grafts
Central vein stenosis Type III stenosis junctional
V. cephalica
Type II stenosis outflow vein
A. brachialis
V. cephalica Type I stenosis juxtaanastomotic
Feeding artery stenosis V. basilica
A. ulnaris
Juxta-anastomotic type I stenosis is the most frequent reason for access dysfunction, especially in the distal radiocephalic AVFs. With endovascular means, in most cases the fibrotic perianastomotic tissue necessitates high-pressure or cutting balloons and prolonged dilatation times, and therefore most authors suggest surgical revision instead, with creation of a new anastomosis a few centimeters proximally; however, in brachiocephalic AVF, a short polytetrafluorethylene segment may be needed to bridge the greater distance between the artery and the vein [5, 6].
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
155
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Fig. 1. Schematic representation of the main types of stenotic lesions complicating accesses.
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Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
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Type II is a mid-vein cannulable segment stenosis and should be first treated with PTA (percutaneous transluminal angioplasty) in autogenous accesses in order to preserve the length of the needling site of the vein; however, in case of failure an interposition graft should be inserted [4]. In this type of lesions, the dialysis dose is usually not affected because the stenosis often falls between the arterial and venous needles [5]. Type I and II stenoses are not frequent in AV grafts, where type III stenosis is the predominant type of stenosis causing access failure and should be treated either by endovascular or open surgical means consisting of patch angioplasty or jump graft repair depending of center’s experience and availability. Regarding the endovascular methods of treatment, stent grafts have better patency rates in comparison to PTA alone according to a recent randomized study [7]. Cephalic arch stenosis is the equivalent of type III stenosis in AVF; PTA should be the first choice as the use of stents may cause axillary vein obstruction, while surgical cephalic vein transposition is an alternative option with equal patency but fewer reinterventions [8]. Stenoses of central veins principally induced by longstanding catheters can become symptomatic as a result of increased flow when an ipsilateral AV fistula is functioning distally to an obstruction. In case of complete venous outflow obstruction, venous hypertension with intractable upper arm painful edema occasionally involving the breast and head may necessitate urgent intervention to avoid tissue loss of the fingers. Access ligation and abandonment bring immediate relief of the complaints but requires a new access creation, which is not always feasible. Surgical repair of the inflow obstruction is not recommended as first choice because of the significant morbidity and mortality of such ‘exotic’ major operations, in opposition, PTA is recommended as the treatment of choice, but it is a matter of debate if primary stenting would be a better option [9]. Arterial inflow stenoses represent atherosclerotic lesions proximal to the anastomosis, and their clinical picture is usually characterized by delayed AVF maturation. These lesions usually involving the radial artery are best treated with PTA [10]. All accesses should be evaluated immediately after their creation and then routinely examined during their life span. After creation of an AVF or AVG, there should be a palpable thrill or a bruit; the presence of a strong pulse in the draining vein without a thrill or bruit indicates a proximal venous stenosis. Monitoring AVF with physical examination by trained physicians represents an accurate method for diagnosis of malfunction [11]. AVF stenoses >50% in diameter should be treated either by surgical or endovascular means when accompanied with low flow, difficulties in cannulation, painful edema or prolonged bleeding at puncture sites [12] (fig. 2). None of the
Vascular access stenosis
Inflow artery stenosis
Type I (perianastomotic)
Type II
PTA
Proximalization of anastomosis
PTA
Surgical repair
Stenting/ stent graft
PTA/ stenting
Failure
Failure
Surgical repair
Central vein stenosis
Type III
Access ligation
Surgical repair (exotic)
Fig. 2. Algorithm of the preferential treatment methods in failing accesses.
currently available surveillance methods (periodic assessment using technical devices) can reliably distinguish between stenosed VA destined to clot, and those that will remain patent without intervention [13]. As a consequence, a percentage of unnecessary angioplasties are performed based on surveillance findings only. Thrombosis of AVF necessitates treatment as quickly as possible because delayed intervention allows the thrombus to propagate, and become fixed to the vein wall with a local inflammation, making any thrombectomy attempt difficult and predisposing to arterial wall damage with its risk of re-thrombosis. Thrombosed VA can be treated either by an open or endovascular intervention. Thrombectomy alone is generally insufficient unless the underlying stenotic lesion is corrected.
Aneurysms may complicate 2–10% of all types of VA [14]. These may be false aneurysms (also called pseudoaneurysms from the Greek word pseudos: false) and true aneurysms caused by degeneration and subsequent dilatation of the
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
157
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Aneurysms
Fig. 3. Skin erosion about to rupture caused by a false aneurysm in a brachiocephalic AVF.
Size exceeding 2-fold the graft diameter Rapid enlargement Skin thinning or erosion Rupture Pain (throbbing) Large or multiple aneurysms limiting the cannulable area Signs of infection Wall-adherent thrombus Anastomotic aneurysms Cosmetic reasons
AVGs
AVFs
– ?
– – – ?
whole native vein wall. In contrast to AVF where true aneurysms are the most frequent type, aneurysms in AVG occur mostly as false aneurysms and less frequently as anastomotic aneurysms. The false aneurysms represent a chronic blood extravasation through a circumscribed graft defect surrounded by thrombi encapsulated in a gradually developed fibrous false wall. The updated DOQI guidelines differentiate between true and false aneurysms and suggest surgical
158
Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
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Table 1. Indications for surgical repair of aneurysms in AVG and AVF
treatment of the enlarging false aneurysms and those exceeding twice the diameter of the graft to prevent the risk of acute rupture. The indications for surgical repair of aneurysms summarizing suggestions from guidelines and articles are presented in table 1 [15, 16]. Access-related aneurysms do not represent per se an indication for surgery; however, anastomotic aneurysms and those with skin erosion should be repaired urgently to avoid rupture and life-threatening hemorrhage (fig. 3). Pseudoaneurysms can be managed either with conventional surgery or with endovascular techniques; however, conventional surgery represents the current standard treatment [17, 18]. Surgical correction includes resection of the involved segment and new graft interposition in situ, or aneurysm ligation/exclusion followed by a bypass graft adjacent to the old one via new route in cases of suspected contamination of the sac [16]. There are many recent series reporting results of stent graft repairs in AVG but with small number of patients and limited follow-up; contraindications of this method include overt graft infection, presence of skin erosion, need to cross the elbow or axilla and lack of adequate landing zones [18, 19]. Aneurysms are often associated with proximal stenosis and both lesions should be treated simultaneously [18]. True aneurysms can be repaired with aneurysmorrhaphy (fig. 4), where the excess sac of the aneurysm is resected, and a new autogenous access is reconstructed by plicating the excess free wall [17].
Infection of autogenous accesses is extremely rare, while AVG could be complicated with two main types of infections: (1) postoperative infections attributable to the initial access procedure with an early onset (50% of the total, with an annual rate of 5% [20]. Bacteremias are 5 times more frequent in grafts than in AVF (3.1 vs. 0.6 bloodstream infections per 100 patient months) [21]. Staphylococcus species are the most common culprits in over 70% of the cases [22]. The difference between AVF and AVG is that infection in autogenous accesses can be treated successfully with antibiotics (and potential drainage) with the exception of those infections involving the anastomosis because of the risk of suture line bleeding and those complicated with septic emboli necessitating access ligation.
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
159
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Infection
a
b
c
160
Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
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Fig. 4. Details how to perform aneurysmorrhaphy to correct true AVF aneurysm: a Incision of overlapping skin with preparation of the aneurysm to control in- and outflow. b Excision of the aneurysmatic vein wall. c Suture line using a tube graft as model to complete a ‘new’ vein with a diameter of approximately 6 mm.
Treatment options for AVG infections comprise: (1) total graft excision, with optional vein patching of the donor artery anastomotic site; (2) subtotal graft excision with an oversewn cuff of prosthetic material left at the donor artery site; the latter avoids hazardous dissection near an artery fixed in scar tissue, minimizing the risk of accidental adjacent nerve damage or hemorrhage, and (3) partial excision of the involved segment only, with interposition of a new graft through an uncontaminated field via a new route [23]. Total graft excision represents the most effective way to eradicate the infection with a very low recurrence rate of 1.6%. In early infections, in the vast majority of cases the graft is not incorporated in the adjacent tissues, and it is easily removed through multiple short incisions; the latter should be left open to heal by secondary intention. Partial excision of the infected segment rescues the access site but has a 29% risk of recurrence. This method is particularly applicable where the infection is ‘late’, usually local in nature and cannot easily spread along a well-incorporated graft [23]. Ultrasound is useful to locate fluid collections and determine the extent of the infection; when there is inflammatory infiltration of the entire graft length, total excision should be undertaken (fig. 5). Although theoretically biological grafts should be preferential over polytetrafluorethylene grafts in infected areas, the former did not fulfill expectations regarding patency and frequently are complicated with aneurysmal degeneration [24].
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
161
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Fig. 5. Infected forearm loop AVG with skin erosion; the inflammatory infiltration involves the entire AVG, and total excision is mandatory.
The best policy to prevent infection is to limit the implantation of synthetic prostheses only to patients with no autogenous options, and in these cases meticulous antiseptic measures and use of surgical drapes are crucial. Avoiding premature puncturing of AVG (
Safety Issues in Surgical and Endovascular Techniques to Rescue Failing or Failed Arteriovenous Fistulas and Arteriovenous Grafts Miltos Lazarides George Georgiadis Christos Argyriou Department of Vascular Surgery, Democritus University Hospital, Alexandroupolis, Greece
Abstract A great variety of thrombotic and nonthrombotic events may complicate all types of vascular access (VA) procedures. Thrombotic events are the most frequent complication, caused by stenoses in various locations, representing a common problem for arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs). Monitoring AVF with physical examination by trained physicians represents an accurate method for diagnosis of malfunction. AVF stenoses >50% in diameter should be treated either by surgical or endovascular means when accompanied with access malfunction. Aneurysms and infections represent the most frequent nonthrombotic VA complications. Access-related aneurysms do not represent per se an indication for intervention; however, anastomotic aneurysms and those with skin erosion should be repaired urgently to avoid rupture. Infections of AVFs are extremely rare, while AVG could be complicated either with postoperative infections attributable to the initial procedure with an early onset and more frequently with late infections caused by punctures, with an annual rate of 5%. Treatment options for AVG infections comprise total or subtotal graft excision or partial excision of the involved segment only, the latter representing a VA salvage procedure but with a significantly higher © 2015 S. Karger AG, Basel risk of recurrence.
• Check after creation of an arteriovenous fistula or arteriovenous graft (AVG) for palpable thrill or a bruit: The presence of a strong pulse in the draining vein without a thrill or bruit indicates a proximal venous stenosis. Patients need an instruction when checking their vascular access (VA) daily for bruit and thrill.
Downloaded by: Fudan University Library 61.129.42.30 - 5/11/2015 9:04:12 PM
Recommendations to Improve Patient Safety
• Failed or failing VA needs revision by surgical or endovascular means depending on the location of the lesion. Check thrombosed accesses after thrombectomy for underlying stenotic lesions that have to be corrected. • Anastomotic aneurysms and those with skin erosion (mostly false aneurysm of AVG) should be repaired urgently to avoid rupture and life-threatening hemorrhage. Patients should be informed about this complication. • Aneurysms are often associated with proximal stenosis, and this should be corrected simultaneously. • The best policy to prevent infection is to limit the implantation of synthetic prostheses only to patients with no autogenous options.
Introduction
The failure of vascular access (VA) represents the major cause of morbidity for those end-stage renal disease patients on hemodialysis, and access maintenance is the most frequent cause of hospitalization for such patients [1]. The subsequent extended length of stay commonly encountered in older patients is also related to further adverse events as hospital-acquired infections and fever, prolonged catheterization predisposing to central venous obstruction and delay in access revision with increased associated costs. The VA maintenance cost increases 5-fold for those patients with a failed autogenous access [2]. A great variety of thrombotic and nonthrombotic events may complicate all types of VA procedures and necessitate a wide spectrum of rescue operations.
Thrombotic events represent the most frequent complication of all VA with an incidence rate of 0.2/patient/year for arteriovenous fistula (AVF) and 0.8/patient/year for synthetic arteriovenous graft (AVG) [3]. Therefore, redo surgery is the rule rather than exception in VA patients. Stenosis is a common problem for AVFs and AVGs and represents the main cause of dysfunction and thrombosis, and the choice of the best method for repair depends on the location of the lesion. Access stenosis has been classified based on its location as: juxta-anastomotic (type I), in the cannulable segment (type II) and at the outflow into the deep venous system (type III) [4] (fig. 1). There are two additional categories of stenoses not involving the access itself, those of the central veins caused by longstanding catheters and those of the arterial inflow [5].
154
Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
Downloaded by: Fudan University Library 61.129.42.30 - 5/11/2015 9:04:12 PM
Stenoses and Thrombosis in Arteriovenous Fistulas or Grafts
Central vein stenosis Type III stenosis junctional
V. cephalica
Type II stenosis outflow vein
A. brachialis
V. cephalica Type I stenosis juxtaanastomotic
Feeding artery stenosis V. basilica
A. ulnaris
Juxta-anastomotic type I stenosis is the most frequent reason for access dysfunction, especially in the distal radiocephalic AVFs. With endovascular means, in most cases the fibrotic perianastomotic tissue necessitates high-pressure or cutting balloons and prolonged dilatation times, and therefore most authors suggest surgical revision instead, with creation of a new anastomosis a few centimeters proximally; however, in brachiocephalic AVF, a short polytetrafluorethylene segment may be needed to bridge the greater distance between the artery and the vein [5, 6].
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
155
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Fig. 1. Schematic representation of the main types of stenotic lesions complicating accesses.
156
Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
Downloaded by: Fudan University Library 61.129.42.30 - 5/11/2015 9:04:12 PM
Type II is a mid-vein cannulable segment stenosis and should be first treated with PTA (percutaneous transluminal angioplasty) in autogenous accesses in order to preserve the length of the needling site of the vein; however, in case of failure an interposition graft should be inserted [4]. In this type of lesions, the dialysis dose is usually not affected because the stenosis often falls between the arterial and venous needles [5]. Type I and II stenoses are not frequent in AV grafts, where type III stenosis is the predominant type of stenosis causing access failure and should be treated either by endovascular or open surgical means consisting of patch angioplasty or jump graft repair depending of center’s experience and availability. Regarding the endovascular methods of treatment, stent grafts have better patency rates in comparison to PTA alone according to a recent randomized study [7]. Cephalic arch stenosis is the equivalent of type III stenosis in AVF; PTA should be the first choice as the use of stents may cause axillary vein obstruction, while surgical cephalic vein transposition is an alternative option with equal patency but fewer reinterventions [8]. Stenoses of central veins principally induced by longstanding catheters can become symptomatic as a result of increased flow when an ipsilateral AV fistula is functioning distally to an obstruction. In case of complete venous outflow obstruction, venous hypertension with intractable upper arm painful edema occasionally involving the breast and head may necessitate urgent intervention to avoid tissue loss of the fingers. Access ligation and abandonment bring immediate relief of the complaints but requires a new access creation, which is not always feasible. Surgical repair of the inflow obstruction is not recommended as first choice because of the significant morbidity and mortality of such ‘exotic’ major operations, in opposition, PTA is recommended as the treatment of choice, but it is a matter of debate if primary stenting would be a better option [9]. Arterial inflow stenoses represent atherosclerotic lesions proximal to the anastomosis, and their clinical picture is usually characterized by delayed AVF maturation. These lesions usually involving the radial artery are best treated with PTA [10]. All accesses should be evaluated immediately after their creation and then routinely examined during their life span. After creation of an AVF or AVG, there should be a palpable thrill or a bruit; the presence of a strong pulse in the draining vein without a thrill or bruit indicates a proximal venous stenosis. Monitoring AVF with physical examination by trained physicians represents an accurate method for diagnosis of malfunction [11]. AVF stenoses >50% in diameter should be treated either by surgical or endovascular means when accompanied with low flow, difficulties in cannulation, painful edema or prolonged bleeding at puncture sites [12] (fig. 2). None of the
Vascular access stenosis
Inflow artery stenosis
Type I (perianastomotic)
Type II
PTA
Proximalization of anastomosis
PTA
Surgical repair
Stenting/ stent graft
PTA/ stenting
Failure
Failure
Surgical repair
Central vein stenosis
Type III
Access ligation
Surgical repair (exotic)
Fig. 2. Algorithm of the preferential treatment methods in failing accesses.
currently available surveillance methods (periodic assessment using technical devices) can reliably distinguish between stenosed VA destined to clot, and those that will remain patent without intervention [13]. As a consequence, a percentage of unnecessary angioplasties are performed based on surveillance findings only. Thrombosis of AVF necessitates treatment as quickly as possible because delayed intervention allows the thrombus to propagate, and become fixed to the vein wall with a local inflammation, making any thrombectomy attempt difficult and predisposing to arterial wall damage with its risk of re-thrombosis. Thrombosed VA can be treated either by an open or endovascular intervention. Thrombectomy alone is generally insufficient unless the underlying stenotic lesion is corrected.
Aneurysms may complicate 2–10% of all types of VA [14]. These may be false aneurysms (also called pseudoaneurysms from the Greek word pseudos: false) and true aneurysms caused by degeneration and subsequent dilatation of the
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
157
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Aneurysms
Fig. 3. Skin erosion about to rupture caused by a false aneurysm in a brachiocephalic AVF.
Size exceeding 2-fold the graft diameter Rapid enlargement Skin thinning or erosion Rupture Pain (throbbing) Large or multiple aneurysms limiting the cannulable area Signs of infection Wall-adherent thrombus Anastomotic aneurysms Cosmetic reasons
AVGs
AVFs
– ?
– – – ?
whole native vein wall. In contrast to AVF where true aneurysms are the most frequent type, aneurysms in AVG occur mostly as false aneurysms and less frequently as anastomotic aneurysms. The false aneurysms represent a chronic blood extravasation through a circumscribed graft defect surrounded by thrombi encapsulated in a gradually developed fibrous false wall. The updated DOQI guidelines differentiate between true and false aneurysms and suggest surgical
158
Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
Downloaded by: Fudan University Library 61.129.42.30 - 5/11/2015 9:04:12 PM
Table 1. Indications for surgical repair of aneurysms in AVG and AVF
treatment of the enlarging false aneurysms and those exceeding twice the diameter of the graft to prevent the risk of acute rupture. The indications for surgical repair of aneurysms summarizing suggestions from guidelines and articles are presented in table 1 [15, 16]. Access-related aneurysms do not represent per se an indication for surgery; however, anastomotic aneurysms and those with skin erosion should be repaired urgently to avoid rupture and life-threatening hemorrhage (fig. 3). Pseudoaneurysms can be managed either with conventional surgery or with endovascular techniques; however, conventional surgery represents the current standard treatment [17, 18]. Surgical correction includes resection of the involved segment and new graft interposition in situ, or aneurysm ligation/exclusion followed by a bypass graft adjacent to the old one via new route in cases of suspected contamination of the sac [16]. There are many recent series reporting results of stent graft repairs in AVG but with small number of patients and limited follow-up; contraindications of this method include overt graft infection, presence of skin erosion, need to cross the elbow or axilla and lack of adequate landing zones [18, 19]. Aneurysms are often associated with proximal stenosis and both lesions should be treated simultaneously [18]. True aneurysms can be repaired with aneurysmorrhaphy (fig. 4), where the excess sac of the aneurysm is resected, and a new autogenous access is reconstructed by plicating the excess free wall [17].
Infection of autogenous accesses is extremely rare, while AVG could be complicated with two main types of infections: (1) postoperative infections attributable to the initial access procedure with an early onset (50% of the total, with an annual rate of 5% [20]. Bacteremias are 5 times more frequent in grafts than in AVF (3.1 vs. 0.6 bloodstream infections per 100 patient months) [21]. Staphylococcus species are the most common culprits in over 70% of the cases [22]. The difference between AVF and AVG is that infection in autogenous accesses can be treated successfully with antibiotics (and potential drainage) with the exception of those infections involving the anastomosis because of the risk of suture line bleeding and those complicated with septic emboli necessitating access ligation.
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
159
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Infection
a
b
c
160
Lazarides Georgiadis Argyriou Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
Downloaded by: Fudan University Library 61.129.42.30 - 5/11/2015 9:04:12 PM
Fig. 4. Details how to perform aneurysmorrhaphy to correct true AVF aneurysm: a Incision of overlapping skin with preparation of the aneurysm to control in- and outflow. b Excision of the aneurysmatic vein wall. c Suture line using a tube graft as model to complete a ‘new’ vein with a diameter of approximately 6 mm.
Treatment options for AVG infections comprise: (1) total graft excision, with optional vein patching of the donor artery anastomotic site; (2) subtotal graft excision with an oversewn cuff of prosthetic material left at the donor artery site; the latter avoids hazardous dissection near an artery fixed in scar tissue, minimizing the risk of accidental adjacent nerve damage or hemorrhage, and (3) partial excision of the involved segment only, with interposition of a new graft through an uncontaminated field via a new route [23]. Total graft excision represents the most effective way to eradicate the infection with a very low recurrence rate of 1.6%. In early infections, in the vast majority of cases the graft is not incorporated in the adjacent tissues, and it is easily removed through multiple short incisions; the latter should be left open to heal by secondary intention. Partial excision of the infected segment rescues the access site but has a 29% risk of recurrence. This method is particularly applicable where the infection is ‘late’, usually local in nature and cannot easily spread along a well-incorporated graft [23]. Ultrasound is useful to locate fluid collections and determine the extent of the infection; when there is inflammatory infiltration of the entire graft length, total excision should be undertaken (fig. 5). Although theoretically biological grafts should be preferential over polytetrafluorethylene grafts in infected areas, the former did not fulfill expectations regarding patency and frequently are complicated with aneurysmal degeneration [24].
Safety Issues in Techniques to Rescue Failing or Failed AVF/AVG Widmer MK, Malik J (eds): Patient Safety in Dialysis Access. Contrib Nephrol. Basel, Karger, 2015, vol 184, pp 153–163 (DOI: 10.1159/000365912)
161
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Fig. 5. Infected forearm loop AVG with skin erosion; the inflammatory infiltration involves the entire AVG, and total excision is mandatory.
The best policy to prevent infection is to limit the implantation of synthetic prostheses only to patients with no autogenous options, and in these cases meticulous antiseptic measures and use of surgical drapes are crucial. Avoiding premature puncturing of AVG (
