Discussion

Dr G. Patrick Clagett (Dallas, Tex). This is one of the larger series of ex-vivo or partially ex-vivo renal artery reconstruction and the results reflect the excellence that one has come to expect from Dr Hansen’s group. My experience pales in comparison, so I have little with which to disagree. However, I have three questions:

One, could you provide more detail regarding the precise nature of the technical problems that led to the need for immediate revision or postoperative occlusion? The overall incidence of this problem was approximately 20% in your series, and it would be helpful to know further details in order to prevent this complication. What led to the occlusions? Small vein graft kinks? Intimal flaps? Anastomotic narrowing?

Two, along these lines, do you think the technique of syndactylizing multiple renal artery branches is sometimes problematic? I have found that this technique can lead to kinking of one or the other branches and does not always anastomose comfortably to a vein graft. Because of this, I have preferred either bypassing to individual branches with branched vein grafts or reimplantation of accessory branches into either the main renal artery, a vein graft or even a vein patch after excision of most of the aneurysm wall.

Three, how important is the potassium-rich renal preservation solution? I agree that the temperature of the renal preservation solution is probably more important than the composition, and I am concerned about the possibility of causing inadvertent hyperkalemia at the completion of the reconstruction. Has this been a problem? I appreciate the opportunity to discuss this paper and commend the authors on an excellent presentation and a fine paper.

Dr Teresa Crutchley: With respect to your first question, we did identify early technical problems in 18.2%, or 12, of our patients. Of those, seven patients were discovered by intraoperative duplex, which we have performed routinely since 1992. Half of the technical problems discovered using intraoperative duplex were defects at the proximal anastomosis or at the aortic clamp sites, and the other half were due to stenoses at the branch level of repair. The remaining five patients were occlusions identified on postoperative angiography. One of these patients was the previously discussed solitary kidney who was anuric postoperatively and was revised immediately for kidney salvage. The remaining four of our occlusions were clinically inapparent until the angiogram obtained a week out from surgery, and were therefore not candidates for intervention.

Regarding your second question about syndactylization, it is our practice to combine segmental branches whenever possible into one or two patches that can be anastomosed to the bypass graft; however, if there is a branch that appears to twist or kink when combined, it will be anastomosed separately.

Finally, with respect to our use of an intracellular-type perfusate, which is potassium-rich, while we agree that hypothermia is the more important adjunctive therapy, we also feel that it is important to use an intracellular composition because it limits the ion exchange and volume shifts that occur when the sodium-potassium ATPase pump is inactivated during periods of hypothermia. This contributes to less cellular edema. We have not encountered problems with hyperkalemia, most importantly because in mobilizing the entire kidney, the collateral blood supply is disrupted. In addition, the renal artery and vein are controlled, as is the ureter. The amount of potassium that enters a patient’s circulation upon release of the clamps is approximately 10 mEq, which corresponds to the amount of perfusate left in the kidney upon re-establishing perfusion.