Is it Safe to Ligate the Left Renal Vein During Open Abdominal Aortic Aneurysm Repair?
Article Outline
Background
Open repair of juxta-renal abdominal aortic aneurysms (AAA) sometimes involves the ligation and division of the left renal vein (LRV). Some surgeons advocate repair, but this is not common practice. The aim was to study the effect of LRV ligation on renal function.
Methods
A retrospective audit of all open AAA repairs between February 2004 and September 2007 in our unit was completed. Pre- and postoperative renal function was assessed with the estimated glomerular filtration rate (eGFR), using an established formula.
Results
Two hundred sixty-one open AAA repairs were performed in the study period. The LRV was ligated in 18.8%; mean age was 75.5 years, 35 were men, mean AAA diameter was 7.8 cm, there were 7 elective, 22 urgent, and 19 emergency AAA repairs. Renal function with LRV ligated was compared with the 212 patients without LRV ligation by independent samples t-testing. The baseline mean serum creatinine and glomerular filtration rate in the LRV ligated group were 115.1 μmol/L and 60.6, respectively, which were similar to the LRV not ligated group (p > 0.05). The renal function at postoperative day 1, day 7, and weeks 2-6 was similar in the two groups (p > 0.05). The postoperative renal function on day 1 was significantly worse compared to baseline (p < 0.05), but not at day 7 and weeks 2-6 (p > 0.05).
Conclusion
In patients undergoing LRV ligation, there is an initial drop in renal function which improves over 2-6 weeks. At each stage, the renal function is similar to patients in whom the LRV is not ligated. LRV ligation is safe during open AAA repair.
Introduction
It is often necessary to divide the left renal vein (LRV) during open repair of abdominal aortic aneurysms (AAA). This maneuver facilitates access to the juxta-renal part of the aorta for clamp placement or proximal anastomosis. With the advent of endovascular aneurysm repair, the AAA repaired by the open method are the difficult and high juxta-renal aneurysms, where ligation and division of the LRV is increasingly necessary. This is also the case in open repair of ruptured AAA, where the retroperitoneal hematoma makes dissection of the aneurysm neck difficult.
There have been few conflicting studies in the past of the effect of LRV division during open AAA repair on postoperative renal function. Some reported minimal long-term sequel, whereas others reported a detrimental effect on postoperative renal function. These contradictory results may be due to differences in methodology, patient selection, and choice of renal function index.1 Serum creatinine is traditionally used to measure renal function, but has been shown to be insensitive in detecting mild to moderate renal impairment.2 Glomerular filtration rate (eGFR) is a more powerful measure of renal function and is superior to serum creatinine in predicting mortality in patients undergoing aortic surgery.3
Some centers advocate repair of the LRV to preserve postoperative renal function. This is not the practice in our unit. The LRV has several tributaries (i.e., adrenal, gonadal, and lumbar), which open up when it is divided and provide an alternative route for venous drainage from the left kidney.4 The aim of this article was to study the effect of LRV division on postoperative renal function as measured by serum creatinine and estimated eGFR during open AAA repair.
Methods
A retrospective audit was carried out on all patients undergoing open AAA repair at the Norfolk and Norwich University Hospital between February 2004 and September 2007. The data were entered prospectively in a computerized hospital (operating theatre and pathology) data base. The patients were divided into two groups: those who had LRV ligation and division, and those who did not. The LRV is always preserved if possible and divided only when access to the aortic neck is difficult and done to obtain better exposure for satisfactory anastomosis. When required, the vein was divided to the right, far from the collaterals veins (gonadal, lumbar, and adrenal veins) and close to the inferior vena cava, although not necessarily flush. The collateral tributaries were always preserved in an attempt to preserve venous drainage from the left kidney. None of the patients in the LRV ligated group had their LRV reconstructed.
Renal function was assessed by measuring serum creatinine preoperatively and on postoperative day 1 (at least 24 hours after the completion of the repair), on day 7, and on day 14-42 (2-6 weeks), depending on when the patient was discharged and followed up in out-patients. The eGFR was estimated from the serum creatinine using the modification of diet in renal disease formula. This formula takes into account the age, sex, and race of the patient while calculating the eGFR and is a popular and accurate method of assessing renal function.5
Data collected on each patient included age, sex, AAA size, timing of surgery (“elective”; “urgent” defined as impending rupture requiring repair within 24 hours; or “emergency” defined as ruptured requiring immediate repair), preoperative state of the patient (“shocked” defined as a systolic BP of <90 mm Hg or “not shocked” defined as a systolic BP >90 mm Hg), clamp position in relation to the renal arteries (supra-renal or infra-renal), graft type (tube, bifurcated intraperitoneal, or bifurcated to the groin) and mortality (30-day mortality). We did not collect data on postoperative medication, hemodialysis requirements, or other renal-protective interventions.
The data were assumed to be normally distributed, and parametric tests of significance were used. The independent samples t-test was used to compare serum creatinine and eGFR between the two groups (LRV ligated and LRV not ligated). The paired sample t-test was used when the postoperative renal function was compared with preoperative values in the same patient. A p < 0.05 was considered significant and all statistical analyses were performed on the statistical analysis software SPSS v14 (Chicago, IL).
Results
During the period between February 2004 and September 2007, a total of 261 patients had open AAA repair. Of these 261 patients, 49 had their LRV ligated, leaving 212 patients with intact LRV. The mean age in the LRV ligated (n = 49) group was 75.5 years with a standard deviation (SD) of 8.4, there were 35 men and the mean size of AAA was 7.8 cm (SD 2.5 cm). This was comparable to the 212 patients with LRV not ligated. Table I shows the demographic data between the two groups. The 30-day mortality in both groups (LRV ligated and LRV not ligated) was 18.4%. We acquired serum creatinine values preoperatively for 256 patients (98%), on day 1 for 243 patients (93%), on day 7 for 214 patients (82%), and between 2 and 6 weeks postoperatively for 170 patients (65%). The serum creatinine measurement used for long-term follow-up (2-6 weeks or 14-42 days) was taken on the 27th day on average, with a SD of 6.9.
Table I. Patient demographics
| LRV ligated (n = 49, 19%) | LRV not ligated (n = 212, 81%) | |
|---|---|---|
| Sex (M:F) | ||
 (M:F) | 35:14 | 181:31 |
| Age (years) | ||
| Mean (SD) | 75.5 (8.4) | 74.5 (7.8) |
| AAA size (cm) | ||
| Mean (SD) | 7.8 (2.5) | 7.6 (2.0) |
| Operation type | ||
| Elective (%) | 7 (2.6%) | 63 (24.1%) |
| Urgent (%) | 22 (8.4%) | 68 (26.1%) |
| Emergency (%) | 19 (7.3%) | 81 (31.0%) |
| Preoperative status | ||
| Shocked (%) | 9 (3.5%) | 80 (30.7%) |
| Not shocked (%) | 40 (50.3%) | 132 (50.6%) |
| Clamp position | ||
| Supra-renal (%) | 12 (4.6%) | 10 (3.8%) |
| Infra-renal (%) | 37 (14.2%) | 202 (77.4%) |
| Graft type | ||
| Tube (%) | 38 (14.6%) | 154 (59.0%) |
| Bifurcated intra-peritoneal (%) | 7 (2.7%) | 75 (28.7%) |
| Bifurcated groin (%) | 2 (0.8%) | 24 (9.2%) |
| Mortality | ||
| Number (%) | 9 (18.4%) | 39 (18.4%) |
The mean serum creatinine at baseline (preoperative) in the LRV ligated group was 115.1 (SD, 40.8) μmol/L, and in the LRV not ligated group was 123.3 (SD, 60.7) μmol/L. The difference was not statistically significant (p = 0.327, independent samples t-test). Table II shows the serum creatinine in the two groups at various time points in the follow-up period (day 1, day 7, and 2-6 weeks). The difference in these results between the two groups was not statistically significant (p > 0.05, independent samples t-test). The eGFR at baseline (preoperative) in the LRV ligated group was 60.6 (SD, 24.2), and in the LRV not ligated group was 60.2 (SD, 22.9). The difference was not statistically significant (p = 0.975, independent samples t-test). Table III shows the eGFR in the two groups at various time points in the follow-up period (on day 1, on day 7, and within 2-6 weeks). The difference in these results between the two groups was not statistically significant (p > 0.05, independent samples t-test).
Table II. Serum creatinine μmol/L means (SD)
| LRV ligated (n = 49) | LRV not ligated (n = 212) | Independent samples t test | |
|---|---|---|---|
| Preoperative creatinine | 115.1 (40.8) | 123.3 (60.6) | p = 0.327 |
| Postoperative day 1 creatinine | 137.2 (63.3)∗ | 130.6 (64.0)∗ | p = 0.680 |
| Postoperative day 7 creatinine | 117.4 (91.1) | 114.1 (88.9) | p = 0.635 |
| Creatinine 2-6 weeks postoperative | 111.9 (66.5) | 115.9 (66.5) | p = 0.656 |
∗p < 0.05 paired samples t-test compared to preoperative creatinine. |
Table III. Glomerular Filtration Rate (eGFR) means (SD)
| LRV ligated (n = 49) | LRV not ligated (n = 212) | Independent samples t test | |
|---|---|---|---|
| Preoperative eGFR | 60.6 (24.2) | 60.2 (22.9) | p = 0.975 |
| Postoperative day 1 eGFR | 48.7 (25.5)∗ | 58.7 (25.2)∗ | p = 0.643 |
| Postoperative day 7 eGFR | 67.1 (39.9) | 72.4 (28.3) | p = 0.121 |
| eGFR 2-6 weeks postoperative | 63.9 (35.2) | 65.9 (23.9) | p = 0.118 |
∗p < 0.05 paired samples t-test compared to preoperative creatinine. |
The renal function was compared at each stage in the postoperative period with the baseline using paired samples t-test within each of the two groups of LRV ligated and LRV not ligated. There was a significant deterioration in renal function (serum creatinine and eGFR) at day 1 compared with baseline (p < 0.05) in each of the two groups, but the difference in renal function on day 7 and days 14-42 as compared with baseline was not statistically significant (p > 0.05, paired samples t-test) (Table II, Table III).
Discussion
Ligation and division of the LRV was first reported by Clark and Leeds in 1961 during resection of a retroperitoneal tumor with no significant deterioration in renal function and survival of the patient.6 In 1967, Neal and Shearburn reported LRV ligation during AAA repair and found it to be a safe and useful adjunct in aortic surgery.7 Over the years, several studies have published contradictory reports of the effect of LRV ligation on postoperative renal function during open AAA repair. In the 1980s, Rastad showed deterioration of renal function in 29 patients and Adar showed the renal function to be unchanged in 15 patients after LRV ligation during AAA repair.8, 9 In the 1990s, Calligaro reported the renal function to be unaltered in 57 patients, and Huber reported a decrease in renal function in 28 patients who had their LRV ligated during open AAA repair.10, 11 In 2000, we concluded LRV ligation to be safe by showing no change in renal function in 56 patients undergoing aortic surgery for aneurysmal and occlusive disease.12 In 2006, West et al. reported a deterioration in renal function in 20 patients undergoing LRV ligation during open AAA repair.13 Clearly other factors are at play. The position of the aortic cross clamp in relation to the renal arteries is important. An aortic clamp placed above the origin of the renal arteries (supra-renal clamp) causes renal ischemia and may impair postoperative renal function. But even if the clamp is infra-renal in position, micro-emboli can be forced into the renal circulation, the so-called renal trash, causing a significant deterioration in postoperative renal function. The age of the patients, the presence of heart disease, and pre-existing renal impairment could be other factors determining postoperative renal function. In ruptured AAA repair, the presence of hypovolumic shock and its duration are also important factors. Renal failure is one of the most important causes of morbidity and mortality in AAA surgery and some studies have looked at the factors contributing to renal failure in these patients. Pre-existing impaired renal function was shown to be an indicator of poor outcome in open AAA repair.14
The technique of LRV ligation is important. We recommend ligating and dividing the LRV close to the inferior vena cava avoiding any of its tributaries in an attempt to preserve the venous return from the left kidney. None of the divided LRVs in our study were reconstructed. Selective reconstruction of the divided LRV is recommended by some surgeons based on the LRV stump pressure and the presence of ballooning or marked distension of the LRV on clamping.10 Others recommend routine reconstruction of the ligated LRV.1 Our study has shown that during open AAA repair, the renal function as assessed by serum creatinine and eGFR is not dissimilar in a group undergoing LRV ligation and a group not undergoing LRV ligation. In our study, in the LRV ligated group, the proportion of patients having an aortic clamp above the renal arteries (supra-renal clamp) as opposed to an infra-renal clamp was higher than in the LRV not ligated group, yet the postoperative renal function was not statistically different. This shows that LRV ligation has little effect on postoperative renal function and should therefore be considered a safe adjunct in open AAA repair. The routine reconstruction of the divided LRV is not necessary and adds precious operative time in these very sick patients.
References
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- Glomerular filtration rate is a predictor of mortality after endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2006;43:14–18
- Glomerular filtration rate is superior to serum creatinine for prediction of mortality after thoracoabdominal aortic surgery. J Vasc Surg. 2005;42:206–212
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- A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of Diet in Renal Disease Study Group. Ann Intern Med. 1999;130:461–470
- . Survival after excision of a kidney, segmental resection of the vena cava, and division of the opposite renal vein. Lancet. 1961;2:1015–1016
- . Division of the left renal vein as an adjunct to resection of abdominal aortic aneurysms. Am J Surg. 1967;113:763–765
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- . Division of the left renal vein during aortic surgery. Am J Surg. 1990;160:192–196
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- . Effect of left renal vein division during aortic surgery on renal function. Ann R Coll Surg Engl. 2000;82:417–420
- Factors affecting outcomes of open surgical repair of pararenal aortic aneurysms: a 10-year experience. J Vasc Surg. 2006;43:921–927discussion 927-928
- . Pathophysiology and prevention of acute renal failure associated with thoracoabdominal or abdominal aortic surgery. J Vasc Surg. 1987;5:518–523
Ethical approval: Not required as determined by the Norfolk & Norwich University Hospital Ethics Committee.
All authors have seen and agreed to the submitted version of the paper and bear responsibility for it. The material is original and has neither been published elsewhere nor submitted for publication simultaneously. If accepted, all authors accept that that this paper will not be published elsewhere in the same or a similar from. All authors have had full access to all the data, they have the right to publish all the data, and they have had the right to obtain independent statistical analyses of the data.
PII: S0890-5096(10)00046-4
doi:10.1016/j.avsg.2010.02.008
© 2010 Published by Elsevier Inc.
