| Abstract|| |
Vascular access for hemodialysis has taxed the ingenuity of surgeons for a long time. Although the Brescia-Cimino arteriovenous fistula has become the principal access, usage of grafts become necessary when suitable artery and vein are not available for making a fistula. A total of 36 grafts for 24 patients were placed at the Riyadh Armed Forces Hospital between January 1988 and December 1989. Three of the grafts were autologous and 33 were synthetic. The forearm was the site of placement in 31 cases, four were placed in the thigh while one was placed in the arm. Twenty-eight complications were encountered during the follow-up period of which thrombosis was the commonest occurring in 14 instances (50%). A total of 23 secondary procedures were performed to prolong graft patency of which thrombectomy was the commonest (52.2%). Eight primary grafts had to be abandoned or replaced by secondary grafts. The overall patency for primary grafts was (87.5%) at six months, (79.1%) at one year and (70.8%) at two years.
Keywords: Grafts, Hemodialysis, Vascular access, PTFE.
|How to cite this article:|
Qattan NM, Dahduli S, Al Jabreen M. Grafts for Hemodialysis Access: Results and Complications. Saudi J Kidney Dis Transpl 1995;6:403-6
|How to cite this URL:|
Qattan NM, Dahduli S, Al Jabreen M. Grafts for Hemodialysis Access: Results and Complications. Saudi J Kidney Dis Transpl [serial online] 1995 [cited 2020 Jan 21];6:403-6. Available from: http://www.sjkdt.org/text.asp?1995/6/4/403/40558
| Introduction|| |
Vascular access has taxed the ingenuity of surgeons for a long time. It constitutes a good bulk of vascular surgical work in the Riyadh Armed Forces Hospital, since our center is one of the earliest to offer hemodialysis (HD) and renal transplantation in the Kingdom of Saudi Arabia  . Notable contributions in the field of vascular access surgery have been the introduction of the QuintonScribner shunt in 1960  , followed by that of the subcutaneous arterio-venous (AV) fistula in 1966  . Since then, the BresciaCimino AV fistula has become the principal access for long-term HD  . However, hence a suitable artery and vein are not available for constructing a fistula, other choices of access procedure, such as various types of grafts are considered, presently, the most successful and safe material for grafts is polytetrafluorethylene (PTFE)  . It was first used by Elliot who described his early studies on dogs  . However, grafts are associated with their own problems and complications. We herewith present our experience on 36 grafts performed on 24 patients on maintenance HD in our center.
| Materials and Methods|| |
A total of 36 grafts, three autologous (saphenous vein) and 33 synthetic, were inserted for HD access in 24 patients at the Riyadh Armed Forces Hospital, Riyadh, during the period from January 1988 to December 1989. The mean age of the study patients was 54.8 years (range 36-80 years). The etiological break down of end-stage renal disease (ESRD) in these patients was as follows: chronic glomerulonephritis (n=16), unknown cause (n = 5), diabetes mellitus (n = 2) and focal glomerulosclerosis (n=l). Patients who were transplanted during the time of the study were not included. A four-year follow-up was available for all our patients. The beginning of 1988 was chosen because it marked the beginning of the use of tapered PTFE graft and only trained vascular surgeons began doing this type of surgery.
The first graft inserted into the patient is called the "Primary Graft". Any procedure to prolong the life of the primary graft is known as secondary procedure. If a second graft was inserted into the same patient after failure of the first one, it is called "Secondary Graft". We always chose a distal inflow e.g. radial artery as first choice. If the flow was not adequate, the brachial artery was chosen. Graft was used only when a fistula could not be performed or salvaged for technical reasons. Straight forearm grafts were performed if the wrist fistula, upon exploration, could not be salvaged in the presence of a good radial artery. In this case, the proximal segment of an adjoining vein or a cubital vein was used for anastomosis.
All the operative room findings were evaluated clinically. We did not have any histological specimens. Neo-intimal hyperplasia was suspected when the graft ends were narrowed with a thrombosed vein proximally. We did not need to perform any angiograms on the operating table on these patients as the clinical findings, assisted with operative Doppler examination, adequately indicated the patency or otherwise, of the inflow and outflow sites of the grafts.
| Results|| |
Of the 36 grafts used in the 24 study patients, 33 were performed using grafts made of PTFE and three with autologous grafts (saphenous vein). All the primary grafts were PTFE grafts. The forearm was the primary choice for placement of the graft and was used in 31 cases of whom 11 were straight and 20 looped. A total of four grafts (1 straight and 3 looped) were placed in the thigh while the arm was chosen for one straight graft. All arm and thigh grafts were secondary grafts after failure of the primary ones and never the first choice.
Of the 36 graft surgeries performed, four primary grafts did not have any complication over the period of the study, while 20 had secondary procedures to prolonged patency.
A total of 28 episodes of complications were encountered in our study patients. Of these, 15 were seen with primary grafts and 13 with secondary grafts. The most common complication was thrombosis of the graft (14 episodes) followed by infection (nine episodes) [Table - 1]. The mean interval between insertion and onset of the first complication was 299 days for primary grafts and 130 days for secondary grafts.
The commonest secondary procedure was thrombectomy in 12 patients (52.2%) followed by incision and drainage of abscess and extension conduits to by-pass venous thrombosis in four patients each (17.4%) [Table - 2].
Eight primary grafts had to be abandoned or replaced by secondary grafts after a mean period of 29 months. Four of these patients received tertiary grafts. There were five cases of failure due to thrombosis and one each due to infection, graft degeneration and lack of venous outflow. The overall patency rate for primary grafts was 87.5% i.e. 21 out of 24, at six months 79.1% i.e. 19 out of 24 at one year and 70.8% 17 out of 24 at two years. Early unexpected failure of three grafts due to thrombosis reduced our overall primary patency rates.
The saphenous vein was used on two occasions as a secondary graft and once, as tertiary. Our results with this graft were not very good and we had to ligate one due to a large pseudoaneurysm and to abandon the other two, which failed due to thrombosis and kinking.
| Discussion|| |
In our experience, the most common complication was graft thrombosis. Similar experience has been reported by others  . Early graft thrombosis is due to technical problems including a proximally thrombosed vein, low flow state, hypotension, hypercoagulability, and early graft usage or tunnel hematoma. Late graft thrombosis is caused by neo-intimal hyperplasia and stenosis at the outflow and inflow tract , . It is our policy to consider graft thrombosis as an emergency and take appropriate action immediately. Almost all the successful graft thrombectomies in our series were performed when the graft thrombosis was diagnosed early during or just after a session of dialysis. The need for early diagnosis cannot be emphasized more strongly.
Graft infections could occur in the early post-operative period or late. Our policy is always to use prophylactic antibiotics, usually with a first generation cephalosporin. Grafts are associated with a higher rate of infection compared with the fistula , . This may be in the form of a needle puncture abscess or an infected hematoma surrounding the graft. The most common organisms found in our patients were Staphylococcus aureus and Streptococcus epidermidis, which is similar to other reports  .
We encountered two cases with false aneurysm. However, we did not lose any graft because of this complication. The false aneurysm could be caused by repeated punctures and injury to a fixed site of the graft. Venous obstruction from stenosis is a potentiating factor for this complication  . The arm and thigh grafts have a higher incidence of false aneurysm due to the high flow and pressure in the graft  .
A graft, crossing the elbow joint is a debatable technical problem due to the possibility of kinking. There is an externally supported graft, e.g. IMPRA Centre-Flex available in the market and has been recommended by some authors  . We did not find any difference in patency rates between the grafts that crossed the elbow joint and those that did not. Similarly, other workers have shown that crossing the elbow with unsupported graft has no adverse effects on the patency of the graft  .
Grafts need a maturation period after insertion to allow for tissue in-growth around them and endothelialization. This will avoid bleeding from the puncture sites as well as pseudoaneurysm formation. It is difficult to exactly specify when a graft could be used and it should be based on clinical judgment.
Graft disintegration was encountered in one case. This graft had been in use for two years and developed an episode of thrombosis.
| Conclusion|| |
Patients on chronic HD are living longer, and their numbers are constantly increasing. Surgeons concerned with the management of patients with ESRD should think about different ways of tackling complications of grafts in order to prolong their patency rates. Amongst the different techniques to be investigated are, the usage of different antithrombotic agents like urokinase, intra operative angioscopy, or inventing prosthetic grafts with less tendency towards thrombosis.
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Nabeel MS Qattan
Department of Surgery, Armed Forces Hospital, P.O. Box 7897, Riyadh 11159
[Table - 1], [Table - 2]