Bridge Grafts for Angioaccess Daniel M. Alterman and Mitchell H. Goldman The public health burden imposed by end-stage renal disease (ESRD) is significant and has increased in prevalence since the turn of the century. In 2005, the U.S. Renal Data System reported that the prevalent dialysis population was 341,000, having increased from 284,000 in 1996. The National Kidney Foundation estimates that chronic kidney disease (CKD) affects about 11% of the U.S. population. Dialysis access dysfunction continues to be a leading cause for hospitalization and morbidity in patients with stage 5 CKD. Adequate management of hemodialysis for a patient with stage 5 CKD includes a functional access that permits needed flow rates, maintains patency, and minimizes complications such as infection or steal. In 1997, the National Kidney Foundation–Kidney Dialysis Outcomes Quality Initiative (KDOQI) collaborated to publish consensus clinical practice guidelines to help improve access outcomes and promote best practice. The primary goals of the KDOQI guidelines are to increase the placement of native fistulas and to encourage detection of access dysfunction before thrombosis develops. If referral for permanent access is made early enough (e.g., stage IV CKD or <30 mL/min creatinine clearance), the time constraint forcing the use of catheters and prosthetic grafts because of their earlier availability would be avoided. The preferable route for hemodialysis access is the autogenous radiocephalic or brachiocephalic fistula, because of their superior patency, ease of access, and lower complication rate. When these sites fail or the veins are inadequate, consideration turns toward prosthetic conduit as a bridge to create an arteriovenous fistula usable for hemodialysis. Conversion of a distal autogenous arteriovenous graft (AVG) with prosthetic can assist future proximal autogenous fistula placement by allowing progressive dilation of more proximal veins. In this way the AVG can be both an anatomic and a temporal bridge. The use of small polytetrafluoroethylene (PTFE) segments instead of vein has several advantages, such as earlier return to hemodialysis use, preventing use of more proximal veins, and allowing dilation of proximal veins, thus making them more robust for future use. Preoperative Considerations Construction and maintenance of reliable shunts in renal dialysis patients is challenging, and care must be taken to avoid compromising tissue perfusion. Duration and frequency of previous access use, venipuncture, arterial lines, operations or trauma, local or systemic infections, and comorbid disease processes are important preoperative considerations. Diabetic patients often come to the hospital with disease of the small- to medium-caliber vessels that are commonly used for angioaccess procedures. Detailed vascular system examination includes assessments of chronic arterial insufficiency, venous thrombosis and valvular incompetence, character and location of arterial pulses, digital capillary refill, and performance of an Allen test. Extremity swelling and venous prominence, particularly in the shoulder and proximal extremity, might suggest underlying venous obstructive disease and requires further investigation. Preoperative cardiopulmonary or other subsystem studies are obtained only as indicated by relevant history and physical findings. The nondominant upper extremity is preferred for initial angioaccess placement to minimize compromise of the patient’s daily activities. Preoperative arteriography and other noninvasive imaging studies are not routinely performed. If there is clinical evidence of venous outflow obstruction, a prior proximal arteriovenous access procedure, recurrent AVG thrombosis, absence of adequate superficial veins, or palpable arterial abnormalities, duplex scanning or contrast radiography is indicated to delineate native vascular anatomy, arterial abnormalities, or proximal venous stenosis. Many patients who come to the hospital with ESRD need immediate central venous system access, and more than 50% require temporary uncuffed catheters within the first 60 days of hemodialysis. Patients often present with catheters in place or have undergone prior central venous access and might have developed central venous stenoses. The subclavian vein is used for temporary access in two thirds of patients presenting for dialysis. The incidence of subclavian vein stenosis after cannulation is 14% to 50%, and thrombosis is 10% to 30%. The incidence of internal jugular vein thrombosis is substantially less (1% to 2%), although no site is free from this risk. The patient’s future need for reliable vascular access is the main objective when considering temporary catheter sites. Use of the extremity contralateral to the proposed surgical site, use of the internal jugular vein before the subclavian vein, and initial avoidance of the femoral vascular system are principles aimed at preserving subsequent potential permanent access sites. A cuffed tunneled catheter can serve as a bridge to permanent access in the acutely ill patient. Infection, patency, and flow rates are similar among various catheter types, and differences in placement technique are minimal. They are associated with central venous stenosis. Preoperative noninvasive ultrasound imaging is often justified in patients being considered for construction of an arteriovenous fistula (AVF). Upper extremity physical examination in candidates for an AVF is sometimes inaccurate in identifying suitable veins for anastomosis. Lack of adequate superficial extremity veins on physical examination often precludes peripheral autogenous fistula construction and is a common reason for proceeding to AVG placement. Extremity AVG placement is not deferred on the basis of insufficient superficial veins on physical examination. The superficial venous system is the preferred outflow channel for initial AVG placement, and the deep venous or more proximal central systems are used secondarily. Preoperative imaging is not routinely obtained in patients presenting for AVG placement unless there is evidence of extensive venous disease. Although technically advantageous, specific identification of venous outflow options is less critical for AVG placement because proximity of the native vessels is not necessary. If there is physical evidence of obstruction to blood flow or valvular incompetence such as edema or venous distention and other sites are not available, construction of the peripheral arteriovenous access is deferred, and the proximal venous system is examined by phlebography or duplex imaging. Placement of an AVG may be prompted by detection of a jeopardized AVF. Even in the absence of symptoms, AVF revision may be needed if a hemodynamically significant stenosis is found. The KDOQI guidelines suggest a 50% or greater than normal vessel lumen reduction of the venous outflow found on color duplex scanning as a main indication for surgical repair or revision. Bridge Grafts The external prosthetic arteriovenous shunt (Scribner shunt) was once the preferred method of establishing arteriovenous access. It is now rarely used for the occasional critically ill patient who is not a candidate for an elective procedure, is without available central venous access, and requires urgent or continuous hemodialysis. Currently, endogenous AVF construction and artificial PTFE AVG remain the most common surgical procedures performed for angioaccess. Conversion or salvage of a jeopardized AVF may be possible by revision with interposition PTFE. Shorter segment (e.g., <6 cm) PTFE interposition grafts have 1- to 2-year patencies comparable to an autogenous tissue salvage repair. There had been a trend toward placing an AVG as the initial hemodialysis access procedure. Prospective incidence data reflect a 50.3% use of PTFE or bovine grafts and a 17.9% use of AVFs at 60 days after dialysis initiation. The KDOQI guidelines have resulted in increased autogenous access, but this might have come at a cost of lower maturation rates because use of suboptimal veins may be increasing. Materials most commonly used for constructing arteriovenous access include carotid artery bovine xenografts, human umbilical vein, PTFE, and Dacron. There is considerable variability in the reported patency rates and quality of xenograft biologic materials, and they have no advantages over primary fistulas and other prosthetic conduits. They are also costly and technically more difficult to use than other materials and are therefore rarely used. Most authors agree that long-term survival of autogenous fistulas is higher than for PTFE, bovine, and saphenous vein bridge grafts. Others report higher patency rates for PTFE conduits, and when early autogenous fistula failures are not considered, the patency rates of PTFE and AVF are similar. In the absence of an AVF, we prefer PTFE to other graft materials because of its durability, ease of use, and secondary long-term patency rates. Traditionally, the more distally placed radial or ulnar artery to cephalic or basilic ulnar vein fistula is the bridge of choice in those presenting for initial arteriovenous access because AVG failure at this site allows construction of more proximal angioaccess. In addition, the dilation of proximal veins resulting from distal fistula construction can facilitate later angioaccess constructions. The looped saphenofemoral and straight popliteal–saphenous fistulas using transposed saphenous vein are methods for constructing lower extremity AVFs. Maturation of a fistula for approximately 6 weeks is recommended. Prosthetic AVG can be used 2 weeks after construction. Although some authors have reported no increase in complications with immediate use, it is generally accepted that early graft use is associated with increased hematoma and infection rates. Some types of PTFE may be used earlier after placement, but they offer no long-term advantage. For constructing looped forearm PTFE AVG, the proximal radial artery takeoff overlapping the brachial artery for a few millimeters is the preferred site of anastomosis in the presence of a patent palmar arch and ulnar artery. The brachial and ulnar arteries can also be used with good results. The primary use of the radial artery decreases the possibility of limb ischemia in the event of AVG thrombosis with brachial artery compromise, and in our experience, the patency rates do not seem to be significantly different. A lateral upper arm approach connecting the brachial artery to the basilic vein with looped PTFE has been advocated in patients who have had multiple previous distal access procedures. The AVG may be secured in an end-to-end or end-to-side anastomosis with the basilic vein in the proximal upper extremity. Both methods provide comparable results if outflow vessels are of adequate caliber and free of distal obstruction. Complete transposition of the basilic vein is not necessary, and ligation of the preanastomotic vein is optional. Other outflow options include the axillary, cephalic, subclavian, or jugular veins. In the absence of a good basilic vein, the axillary vein may be used. Lower extremity AVG is considered when upper extremity sites are not available. Our preferred construct at this location is the superficial femoral artery to saphenofemoral vein PTFE loop graft. Arteriovenous connection of the common femoral, profunda femoris, and popliteal artery (above the knee) to the common femoral or proximal saphenous veins are suitable alternatives. Disadvantages of lower extremity AVGs include increased infection and thrombosis rates. These arteriovenous bridges are the preferred alternative to proximal extra-anatomic procedures that require extensive dissection under general anesthesia in a patient population usually presenting late in the course of their disease with multiple comorbidities. Patient’s discomfort and AVG accessibility are additional considerations. Other possibilities for prosthetic arteriovenous access include ipsilateral loop or cross-chest axilloaxillary, axillofemoral, and femorofemoral AVGs. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Technical Aspects of Percutaneous Carotid Angioplasty and Stenting for Arteriosclerotic Disease In-Situ Treatment of Aortic Graft Infection with Prosthetic Grafts and Allografts Treatment of Dyslipidemia and Hypertriglyceridemia Endovascular Renal Denervation Stay updated, free articles. Join our Telegram channel Join Tags: Current Therapy in Vascular and Endovascular Surgery Aug 25, 2016 | Posted by admin in CARDIOLOGY | Comments Off on Bridge Grafts for Angioaccess Full access? Get Clinical Tree
Bridge Grafts for Angioaccess Daniel M. Alterman and Mitchell H. Goldman The public health burden imposed by end-stage renal disease (ESRD) is significant and has increased in prevalence since the turn of the century. In 2005, the U.S. Renal Data System reported that the prevalent dialysis population was 341,000, having increased from 284,000 in 1996. The National Kidney Foundation estimates that chronic kidney disease (CKD) affects about 11% of the U.S. population. Dialysis access dysfunction continues to be a leading cause for hospitalization and morbidity in patients with stage 5 CKD. Adequate management of hemodialysis for a patient with stage 5 CKD includes a functional access that permits needed flow rates, maintains patency, and minimizes complications such as infection or steal. In 1997, the National Kidney Foundation–Kidney Dialysis Outcomes Quality Initiative (KDOQI) collaborated to publish consensus clinical practice guidelines to help improve access outcomes and promote best practice. The primary goals of the KDOQI guidelines are to increase the placement of native fistulas and to encourage detection of access dysfunction before thrombosis develops. If referral for permanent access is made early enough (e.g., stage IV CKD or <30 mL/min creatinine clearance), the time constraint forcing the use of catheters and prosthetic grafts because of their earlier availability would be avoided. The preferable route for hemodialysis access is the autogenous radiocephalic or brachiocephalic fistula, because of their superior patency, ease of access, and lower complication rate. When these sites fail or the veins are inadequate, consideration turns toward prosthetic conduit as a bridge to create an arteriovenous fistula usable for hemodialysis. Conversion of a distal autogenous arteriovenous graft (AVG) with prosthetic can assist future proximal autogenous fistula placement by allowing progressive dilation of more proximal veins. In this way the AVG can be both an anatomic and a temporal bridge. The use of small polytetrafluoroethylene (PTFE) segments instead of vein has several advantages, such as earlier return to hemodialysis use, preventing use of more proximal veins, and allowing dilation of proximal veins, thus making them more robust for future use. Preoperative Considerations Construction and maintenance of reliable shunts in renal dialysis patients is challenging, and care must be taken to avoid compromising tissue perfusion. Duration and frequency of previous access use, venipuncture, arterial lines, operations or trauma, local or systemic infections, and comorbid disease processes are important preoperative considerations. Diabetic patients often come to the hospital with disease of the small- to medium-caliber vessels that are commonly used for angioaccess procedures. Detailed vascular system examination includes assessments of chronic arterial insufficiency, venous thrombosis and valvular incompetence, character and location of arterial pulses, digital capillary refill, and performance of an Allen test. Extremity swelling and venous prominence, particularly in the shoulder and proximal extremity, might suggest underlying venous obstructive disease and requires further investigation. Preoperative cardiopulmonary or other subsystem studies are obtained only as indicated by relevant history and physical findings. The nondominant upper extremity is preferred for initial angioaccess placement to minimize compromise of the patient’s daily activities. Preoperative arteriography and other noninvasive imaging studies are not routinely performed. If there is clinical evidence of venous outflow obstruction, a prior proximal arteriovenous access procedure, recurrent AVG thrombosis, absence of adequate superficial veins, or palpable arterial abnormalities, duplex scanning or contrast radiography is indicated to delineate native vascular anatomy, arterial abnormalities, or proximal venous stenosis. Many patients who come to the hospital with ESRD need immediate central venous system access, and more than 50% require temporary uncuffed catheters within the first 60 days of hemodialysis. Patients often present with catheters in place or have undergone prior central venous access and might have developed central venous stenoses. The subclavian vein is used for temporary access in two thirds of patients presenting for dialysis. The incidence of subclavian vein stenosis after cannulation is 14% to 50%, and thrombosis is 10% to 30%. The incidence of internal jugular vein thrombosis is substantially less (1% to 2%), although no site is free from this risk. The patient’s future need for reliable vascular access is the main objective when considering temporary catheter sites. Use of the extremity contralateral to the proposed surgical site, use of the internal jugular vein before the subclavian vein, and initial avoidance of the femoral vascular system are principles aimed at preserving subsequent potential permanent access sites. A cuffed tunneled catheter can serve as a bridge to permanent access in the acutely ill patient. Infection, patency, and flow rates are similar among various catheter types, and differences in placement technique are minimal. They are associated with central venous stenosis. Preoperative noninvasive ultrasound imaging is often justified in patients being considered for construction of an arteriovenous fistula (AVF). Upper extremity physical examination in candidates for an AVF is sometimes inaccurate in identifying suitable veins for anastomosis. Lack of adequate superficial extremity veins on physical examination often precludes peripheral autogenous fistula construction and is a common reason for proceeding to AVG placement. Extremity AVG placement is not deferred on the basis of insufficient superficial veins on physical examination. The superficial venous system is the preferred outflow channel for initial AVG placement, and the deep venous or more proximal central systems are used secondarily. Preoperative imaging is not routinely obtained in patients presenting for AVG placement unless there is evidence of extensive venous disease. Although technically advantageous, specific identification of venous outflow options is less critical for AVG placement because proximity of the native vessels is not necessary. If there is physical evidence of obstruction to blood flow or valvular incompetence such as edema or venous distention and other sites are not available, construction of the peripheral arteriovenous access is deferred, and the proximal venous system is examined by phlebography or duplex imaging. Placement of an AVG may be prompted by detection of a jeopardized AVF. Even in the absence of symptoms, AVF revision may be needed if a hemodynamically significant stenosis is found. The KDOQI guidelines suggest a 50% or greater than normal vessel lumen reduction of the venous outflow found on color duplex scanning as a main indication for surgical repair or revision. Bridge Grafts The external prosthetic arteriovenous shunt (Scribner shunt) was once the preferred method of establishing arteriovenous access. It is now rarely used for the occasional critically ill patient who is not a candidate for an elective procedure, is without available central venous access, and requires urgent or continuous hemodialysis. Currently, endogenous AVF construction and artificial PTFE AVG remain the most common surgical procedures performed for angioaccess. Conversion or salvage of a jeopardized AVF may be possible by revision with interposition PTFE. Shorter segment (e.g., <6 cm) PTFE interposition grafts have 1- to 2-year patencies comparable to an autogenous tissue salvage repair. There had been a trend toward placing an AVG as the initial hemodialysis access procedure. Prospective incidence data reflect a 50.3% use of PTFE or bovine grafts and a 17.9% use of AVFs at 60 days after dialysis initiation. The KDOQI guidelines have resulted in increased autogenous access, but this might have come at a cost of lower maturation rates because use of suboptimal veins may be increasing. Materials most commonly used for constructing arteriovenous access include carotid artery bovine xenografts, human umbilical vein, PTFE, and Dacron. There is considerable variability in the reported patency rates and quality of xenograft biologic materials, and they have no advantages over primary fistulas and other prosthetic conduits. They are also costly and technically more difficult to use than other materials and are therefore rarely used. Most authors agree that long-term survival of autogenous fistulas is higher than for PTFE, bovine, and saphenous vein bridge grafts. Others report higher patency rates for PTFE conduits, and when early autogenous fistula failures are not considered, the patency rates of PTFE and AVF are similar. In the absence of an AVF, we prefer PTFE to other graft materials because of its durability, ease of use, and secondary long-term patency rates. Traditionally, the more distally placed radial or ulnar artery to cephalic or basilic ulnar vein fistula is the bridge of choice in those presenting for initial arteriovenous access because AVG failure at this site allows construction of more proximal angioaccess. In addition, the dilation of proximal veins resulting from distal fistula construction can facilitate later angioaccess constructions. The looped saphenofemoral and straight popliteal–saphenous fistulas using transposed saphenous vein are methods for constructing lower extremity AVFs. Maturation of a fistula for approximately 6 weeks is recommended. Prosthetic AVG can be used 2 weeks after construction. Although some authors have reported no increase in complications with immediate use, it is generally accepted that early graft use is associated with increased hematoma and infection rates. Some types of PTFE may be used earlier after placement, but they offer no long-term advantage. For constructing looped forearm PTFE AVG, the proximal radial artery takeoff overlapping the brachial artery for a few millimeters is the preferred site of anastomosis in the presence of a patent palmar arch and ulnar artery. The brachial and ulnar arteries can also be used with good results. The primary use of the radial artery decreases the possibility of limb ischemia in the event of AVG thrombosis with brachial artery compromise, and in our experience, the patency rates do not seem to be significantly different. A lateral upper arm approach connecting the brachial artery to the basilic vein with looped PTFE has been advocated in patients who have had multiple previous distal access procedures. The AVG may be secured in an end-to-end or end-to-side anastomosis with the basilic vein in the proximal upper extremity. Both methods provide comparable results if outflow vessels are of adequate caliber and free of distal obstruction. Complete transposition of the basilic vein is not necessary, and ligation of the preanastomotic vein is optional. Other outflow options include the axillary, cephalic, subclavian, or jugular veins. In the absence of a good basilic vein, the axillary vein may be used. Lower extremity AVG is considered when upper extremity sites are not available. Our preferred construct at this location is the superficial femoral artery to saphenofemoral vein PTFE loop graft. Arteriovenous connection of the common femoral, profunda femoris, and popliteal artery (above the knee) to the common femoral or proximal saphenous veins are suitable alternatives. Disadvantages of lower extremity AVGs include increased infection and thrombosis rates. These arteriovenous bridges are the preferred alternative to proximal extra-anatomic procedures that require extensive dissection under general anesthesia in a patient population usually presenting late in the course of their disease with multiple comorbidities. Patient’s discomfort and AVG accessibility are additional considerations. Other possibilities for prosthetic arteriovenous access include ipsilateral loop or cross-chest axilloaxillary, axillofemoral, and femorofemoral AVGs. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Technical Aspects of Percutaneous Carotid Angioplasty and Stenting for Arteriosclerotic Disease In-Situ Treatment of Aortic Graft Infection with Prosthetic Grafts and Allografts Treatment of Dyslipidemia and Hypertriglyceridemia Endovascular Renal Denervation Stay updated, free articles. Join our Telegram channel Join
