particularly in the setting of hemodynamically signifi- cant stenosis (9). A concurrent stenosis at the venous anastomosis will increase intragraft pressure and force blood through the graft wall into the surrounding tissue creating a pseudoaneurysm (9). With increased intra- graft pressure, pseudoaneurysms increase in size and may rupture (9). Thus, pseudoaneurysms must be moni- tored closely with frequent examinations of size and skin texture over the aneurismal area (9,10). If the skin over- lying the aneurysm slides easily over the underlying tis- sue, rupture risk is less as this indicates a healthy subcutaneous layer overlying the aneurysm (10). Management of pseudoaneursyms has traditionally focused on percutaneous correction of the stenosis and surgical resection. Initial surgical management is gener- ally deferred unless there is evidence of imminent rupture (i.e. bleeding, or overlying skin breakdown) or if pseud- oaneurysm size is interfering with graft cannulation (9). Definitive management consists of surgical resection of the aneurysmal segment of graft and overlying skin, and repair of the defect with a patch or interposition graft (10). Recently, percutaneous management with the placement of self-expanding stents in the pseudoaneurysm’s area has been attempted with moderate success (8,9) and offers an option for patients who are poor surgical candidates. Another less common indication for AVG surgery is steal syndrome. Steal syndrome, a condition that devel- ops within days to weeks of AVG placement occurs in anywhere from 2% to 20% of AVF or AVG creations (11). Risk factors for its development include diabetes, advanced age, and female gender; these patients often have poor circulation due to atherosclerotic disease, and / or small caliber arteries. Pain, numbness, tingling, and cool extremities characterize this syndrome. Surgery to either reduce flow through the AVG, improve distal flow via revascularization, or both is undertaken and is generally successful, although ligation of the access is sometimes required (11). Currently there are only a few indications for surgical removal of an AVG. As advances in percutaneous techniques rapidly become available, the need for surgi- cal intervention will continue to decline. To date how- ever, surgical removal of entire grafts or portions of grafts is still required in the setting of AVG infection and enlarging pseudoanuerysms. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland Address correspondence to: Mohamed G. Atta MD, MPH, 1830 E. Monument Street, Suite 416, Baltimore, MD 21287, USA, Tel.: 410-955-5268, Fax: 410-955-0485, or e-mail: matta1@jhmi.edu. References 1. Haddad NJ, et al.: Iatrogenic graft to vein fistula (GVF) formation associ- ated with synthetic arteriovenous grafts. Semin Dial 23:643–647, 2010 2. Akoh JA: Prosthetic arteriovenous grafts for hemodialysis. J Vasc Access 10:137–147, 2009 3. Salman L, et al.: Antibiotic prophylaxis: is it needed for dialysis access proce- dures? Semin Dial 22:297–299, 2009 4. Ryan SV, et al.: Management of infected prosthetic dialysis arteriovenous grafts. J Vasc Surg 39:73–78, 2004 5. Schmidt G: Differential Diagnosis in Ultrasound Imaging: A Teaching Atlas. : Georg Theime, 2006 6. Ryan SV, et al.: Management of hemodialysis access infections. Semin Vasc Surg 17:40–44, 2004 7. Nassar GM, et al.: Infectious complications of the hemodialysis access. Kidney Int 60:1–13, 2001 8. Najibi S, et al.: Covered stent exclusion of dialysis access pseudoaneurysms. J Surg Res 106:15–19, 2002 9. Vesely TM: Use of stent grafts to repair hemodialysis graft-related pseudoaneurysms. J Vasc Interv Radiol 16:1301–1307, 2005 10. Gelbfish GA: Surgical versus percutaneous care of arteriovenous access. Semin Vasc Surg 20:167–174, 2007 11. Suding PN, et al.: Strategies for management of ischemic steal syndrome. Semin Vasc Surg 20:184–188, 2007 When and how should an arterio-venous access be modified because of a high blood flow rate? Carlo Basile and Carlo Lomonte It has long been known that a vascular access (VA) with an inappropriately high-flow rate may cause high-output heart failure (1,2). The incidence of this complication remains unknown: one study found a 3.7% (17 / 460) incidence of high-flow rate VAs requiring surgical cor- rection (3). A strong relationship exists between blood flow rate (Qa) and cardiac output (CO): Qa = 0.20 CO + 0.06 (r = 0.62; p = 0.01) (4). High-Flow Rate VAs Recent data show that relatively higher Qa of arterio- venous fistulas (AVFs) appear to be associated with a lower level of hemodialysis-induced cardiac injury (5) and not to represent an independently increased risk of death (6). No agreement exists in the literature about the definition of high-flow rate AVFs and about possible car- diovascular effects. The Vascular Access Society Guide- lines define as high-flow rate an AVF with Qa of 1000– 1500 ml / min and a cardio-pulmonary recirculation (CPR) (i.e., the ratio Qa / CO) >20% (7). Some authors have stressed the importance of the relationship between Seminars in Dialysis—Vol 24, No 4 (July–August) 2011 pp. 396–398 DOI: 10.1111/j.1525-139X.2011.00887.x ª 2011 Wiley Periodicals, Inc. 396 Basile and Lomonte