Factors Influencing Outcome after Open Surgical Repair of Juxtarenal Abdominal Aortic Aneurysms

Discussion

This case series study from a single academic referral center of patients who underwent conventional open JR-AAA repair with suprarenal clamping, a technically more complex and high-risk surgical repair than subrenal clamping, the reference procedure during the past 10 years, extends the current literature, underlining the promising cardiorespiratory and renal morbidity and mortality outcomes and good overall survival at 1, 3, and 5 years (almost 90% at 5 years). Our findings also confirm the known factors predicting cardiorespiratory and renal morbidity and mortality.

One of the major problems in open JR-AAA repair is identifying on preoperative imaging patients whose pararenal aorta is unsuitable for clamping.^[10,11] In our series, the detailed preoperative imaging workup correctly identified and excluded patients whose pararenal aorta seemed unsuitable for clamp placement and therefore necessitated clamping above the superior mesenteric or celiac artery (SR-AAAs).^[6,7] Hence, none of the JR-AAAs in this series required supravisceral clamping. Another useful technical point was that our routine practice of mobilizing the left renal vein and partly dissecting the diaphragmatic pillars invariably fully exposed the proximal aneurysm neck, thus making the suprarenal artery easier to clamp. The fact that we never needed to clamp the supravisceral aorta may also in part explain the relatively low incidence of acute myocardial ischemia during the immediate postoperative course, an outcome that on univariate analysis was, however, significantly associated with preoperative ischemic heart disease. Supravisceral clamping notably increases the risk of hemodynamic myocardial stress and ischemic organ damage.^[12] Reported perioperative cardiac complication rates range from 0 to 10%, consisting mainly of ischemic heart disease and accounting for 30 to 40% of total mortality in patients undergoing open JR-AAA repair.^[1,12] Ideal clamping nonetheless still remains debatable^[13] because many investigators a priori favor supraceliac clamping to avoid further burdening an atherosclerotic tract and hence to reduce the risk of distal embolization.^[14]

Although we did not investigate whether clinical outcomes differed for the three surgical approaches because most patients (76 of 92) underwent surgery with a transperitoneal approach after a standard midline incision, the operating surgeon chose the surgical approaches according to the individual patients' clinical and morphologic features. Our study underlines the importance of choosing a surgical approach that will reduce the risk of postoperative respiratory insufficiency. Probably because we used a transverse subcostal laparotomy approach for all obese patients and those with respiratory insufficiency, few patients who underwent open JR-AAA repair in this series had postoperative respiratory complications, consisting in most cases of pleural effusion in patients with protein imbalance and hypoalbuminemia. Numerous publications show that patients who undergo abdominal surgery are at risk of worsening respiratory function, mainly attributable to postoperative pain.^[15,16] Our findings agree with those who state that clinical symptoms of surgery-related pain seem to be associated not with surgery itself but with the type of incision.^[15]

Our findings in this series underline the influence of clamping time on renal function. In all of our patients, inferior suprarenal artery clamping lasted less than 35 minutes, thus protecting the renal parenchyma against ischemic damage.^[17–19] Support for this conclusion came from the acceptable rate of renal insufficiency and univariate analysis showing that the only significant predictor of postoperative renal insufficiency was a preoperative creatine clearance of ≤ 40 mL/min.

In our series, five patients suffered from preoperative chronic renal insufficiency. During these patients' postoperative course, their serum creatinine levels increased and creatinine clearance decreased by a mean 6%; in four of these, creatinine clearance returned to a barely lower level than baseline on postoperative day 5, so that at discharge, these patients' renal function was almost unchanged.

In patients who had normal renal function before surgery and doubling of serum creatinine to more than 2 mg/dL afterward, serum creatinine values returned to normal at discharge, with a maximum range of more than 0.2 mg/dL higher than the preoperative values. This outcome is in line with the previous suggestions that renal insufficiency depends on factors other than hypercreatinemia.^[4,20] Postoperative renal insufficiency is a common complication after JR-AAA surgical repair and in most cases is caused by acute tubular necrosis.^[11,21] The incidence ranges from 12 to 30%, requiring hemodialysis in up to 13% of cases.^[21,22]

An operative procedure we routinely use in patients undergoing open JR-AAA repair is infusion of cold crystalloid solutions for reducing parenchymal tissue metabolism and damage from ischemia and reperfusion.^[17,19] Our findings suggest that selective crystalloid perfusion is a protective factor and takes only a few seconds. It also protects against worsening preoperative renal failure even though without a group of unperfused control patients we cannot definitively evaluate its effectiveness.

An interesting finding that merits further investigation is the significant univariate association between postoperative renal insufficiency and female gender. A possible anatomic explanation comes from evidence that aortic morphology differs in the two genders.^[23] The differences reach statistical significance for diameter, angulation of the renal artery and their origin from the aorta, and their position at the renal hilum. The smaller arterial diameter and more posterior site of emergence in association with atherosclerotic aneurysms could increase the incidence of distal emboli during clamp placement. This hypothesis nevertheless needs validating in a larger case series to find out whether it arose merely by chance owing to the larger number of female patients than males with preoperative renal failure.

Notwithstanding the limitations of a retrospective study, our experience over the past 10 years emphasizes that in patients carefully selected according to preoperative imaging criteria to undergo elective open JR-AAA repair with suprarenal clamping, appropriate intraoperative surgical management will guarantee good immediate postoperative rates of death and cardiorespiratory and renal complications and a 5-year survival rate now approaching 90%.

Vascular. 2010;18(3):141-146. © 2010 BC Decker, Inc.

Cite this: Factors Influencing Outcome after Open Surgical Repair of Juxtarenal Abdominal Aortic Aneurysms - Medscape - Jun 01, 2010.