Data dispute en bloc ligation, arteriovenous fistula link during nephrectomy

May 1, 2008

Researchers now have evidence that the risk of arteriovenous fistula formation is low in patients who undergo en bloc ligation.

As urologists challenge the limits of laparoscopic surgery, this issue is of in- creasing importance. Researchers from the University of Tennes- see at Knoxville now have evidence that the risk of arteriovenous fistula formation is low in patients who undergo en bloc ligation.

Wesley M. White, MD, chief urology resident working with Judson Gash, MD, Frederick Klein, MD, and W. Bedford Waters, MD, performed a prospective evaluation on 65 patients who underwent en bloc ligation of the renal hilum during hand-assisted laparoscopic nephrectomy for malignant disease. A 45-mm titanium endovascular stapler (Endovascular GIA, Ethicon/Johnson & Johnson, Somerville, NJ) with a 2.5-mm vascular load was used to ligate the pedicle en bloc. Patients were followed clinically for evidence of arteriovenous fistula formation, such as hypertension, abdominal bruit, or new-onset congestive heart failure.

There was no statistically significant difference in preoperative and postoperative blood pressure (p=.19 and p=.59, respectively), no abdominal bruits on physical exam, and no new-onset congestive heart failure, Dr. White reported at the World Congress of Endourology here. Fifteen patients exhibited creatinine values greater than 1.5 mg/dL, and were therefore excluded from follow-up imaging. Twenty-eight patients had follow-up of at least 12 months, and they were eligible for CT angiography. No arteriovenous fistulas were seen in any of these patients.

The advantages of en bloc ligation of the pedicle extend from the ability to dissect the artery and vein out together, rather than separately. This decreases the amount of dissection required in the delicate region of the hilum.

"This approach can decrease operative time, decrease the potential for blood loss and injury, and should be considered," Dr. White urged.

Incidents of stapler malfunction are about 1.7%. An advantage of the stapler over Hem-o-lok clips (Teleflex Medical, Research Triangle Park, NC) is that stapler malfunction is often recognized immediately in the intraoperative setting, while clip malfunction may not be appreciated until the postoperative period.

The instrument is typically positioned perpendicular to the renal artery and vein, parallel to the great vessels. This technique is modified in accordance with the individual patient's anatomy and the most direct route of access to the vessels.

One limitation of this study is the exclusion of the 15 patients with a creatinine of 1.5 mg/dL or greater. Dr. White said he considered using ultrasound to image these patients, but did not want to obscure the analysis by using more than one imaging modality.

A second limitation is the intermediate length of follow-up, approximately 3 years. Because the exact timing of fistula formation is un-known, the length of appropriate follow-up is unclear.

Finally, these re- sults can be generalized only to hand-assisted laparoscopic nephrectomy for malignant disease because that was the population evaluated.

Dr. White and colleagues concluded that the risk of arteriovenous fistula formation is very low. After an average follow-up of 37.8 months, there was no clinical evidence of fistula in 58 patients and no radiographic evidence in 28 patients.

"There is a long-standing dogma that en bloc ligation causes renal fistulae," said Dr. White. "Hopefully, our data will help dispel that rumor."