Preservation of renal function in juxtarenal and suprarenal abdominal aortic aneurysm repair

Kidney protection in thoracoabdominal aortic aneurysm surgery

Acute kidney injury (AKI) is a common complication of both open and endovascular repair of thoracoabdominal aortic aneurysms (TAAA). Its definition varies across difference studies, some standardized definitions (RIFLE, AKIN, KDIGO) have been proposed but still not uniformly employed in published papers. Acute kidney injury is multifactorial and is associated with increased in-hospital mortality, long-term mortality and late renal function decline. In addition, AKI is also associated with perioperative spinal cord ischemia. No specific pharmacological strategy has received a strong recommendation with high level of evidence as a protective measure. Fenoldopam, methylprednisolone or mannitol use to prevent AKI is commonly employed, but not supported by literature data. Avoiding nephrotoxic drugs and maintaining an adequate MAP, during and after the procedure plays a key role in preserving kidney function. During open TAAA surgery, renal arteries may be reimplanted using different techniques. The choice of the best option must be tailored to the patient, to reduce ischemic time and guarantee long-term patency. Current experience suggests that cold crystalloid solutions are the best substrates in preventing ischemia-reperfusion injury. Renal perfusion using Custodiol^® (Dr Franz-Kohler Chemie GmbH; Bensheim, Germany) 4 °C, even if currently considered off-label, represents an encouraging organ protection tool. In endovascular TAAA repair, techniques such as fusion imaging, use of diluted contrast, and CO<inf>2</inf> subtraction angiography have the potential to reduce postoperative AKI. Visceral vessels patency is closely related to the anatomy. Therefore, accurate endograft design according to these characteristics is crucial for long-term preservation of renal function.

Surgical Repair of Juxtarenal Abdominal Aortic Aneurysms and safety of Suprarenal Aortic Clamping

BACKGROUND

Juxtarenal abdominal aortic aneurysm (AAA) comprises 15-20% of all AAAs and often requires open surgical repair (OSR) due to anatomical limitations associated with endovascular aneurysm repair (EVAR), particularly in the case of hostile proximal necks. This study aimed to evaluate short- and long-term outcomes of suprarenal clamping during OSR of juxtarenal AAAs and compare the outcomes of this technique with those of infrarenal clamping for AAAs.

METHODS

Between January 1 2014, and December 31 2016, 289 consecutive patients aged ≥40 years underwent primary repair for infrarenal AAAs, including 141 OSRs and 148 EVARs. Of the 141 patients, 20 were excluded and totally, 121 patients were included.

RESULTS

All patients had fusiform-type AAAs and were divided into infrarenal (N = 98) or suprarenal (N=23) clamp groups. The mean follow-up period was 51.4 months (95% CI: 48.6-54.2). Mean survival time was 51.4 months (95% CI: 48.6-54.2). Thirty-day mortality was 0.8%, and there was no significant difference between two groups (P > .999). Renal complication in infrarenal clamp group was 4.1% and suprarenal clamp group was 4.3% (P > .999). Old age (HR: 1.084; 95% CI: 1.025-1.147; P=.005) and high ASA score (HR: 2.361; 95% CI: 1.225-4.553; P = .010) were substantially associated with in-hospital complications.

CONCLUSIONS

Although endovascular procedures for repairing juxtarenal AAAs, such as fenestrated EVAR, have been developed, surgical repair is the standard treatment for juxtarenal AAAs. Morbidity and mortality due to open surgery were not higher in the juxtarenal AAA group than in the infrarenal AAA group. Therefore, need for suprarenal clamp should not preclude OSR and also there is continued need for training in surgical exposure of juxtarenal AAA and OSR.

The use of a low-profile stent graft with a polymer ring sealing technology combined with bare renal stent (vent technique) in patients with juxtarenal aneurysm not eligible for open surgery and fenestrated endograft

OBJECTIVE

In cases of juxtarenal abdominal aortic aneurysm (jAAA), endovascular aneurysm repair (EVAR) involves the use of custom-made fenestrated stent grafts, which usually need large-diameter access vessels, superior costs, and a certain time between graft planning and delivery. We report our preliminary experience using the bare renal stent technique (called vent) in combination with the ultralow-profile stent graft Ovation (Endologix, Irvine, Calif) to seal jAAAs in patients evaluated to be unfit for open surgery and not suitable for fenestrated endograft.

METHODS

A single-center retrospective review of jAAAs treated by Ovation vent technique from January 2015 to December 2018 was conduced. The vent procedure consisted of a modified, off-label deployment of the sealing ring of the ultralow-profile Ovation stent graft close to renal orifices in combination with short bare-metal stents. The exclusion criterion was a diameter >31 mm at the level of the lowest renal artery. Early technical and clinical results, estimated midterm survival, renal artery patency, freedom from type IA endoleak, freedom from reintervention, and freedom from neck enlargement (>2 mm) were reported.

RESULTS

Overall, 38 patients had jAAA and were considered unfit for open repair and not eligible for fenestrated EVAR. The proximal neck was <5 mm in all cases (mean, 3.3 ± 1.2 mm). Vent renal stents were implanted bilaterally in 16 patients. Primary technical success was 94.7% (36/38), with satisfactory cannulation of all renal arteries and sealing of the aneurysm in all but two cases because of type IA endoleaks that were treated immediately with success. Primary clinical success at 1 month was 100%. During a median follow-up period of 22.4 ± 3.6 months (range, 1-46 months), no abdominal aortic aneurysm-related deaths occurred, and no patient was lost to follow-up. The survival curve at 1 year and 2 years was, respectively, 96.4% and 91.6% (standard error, 0.57%). There were no cases of neck dilation or endograft migration. Freedom from reintervention at 12 months and 24 months was 100% and 89.5%, respectively (standard error, 0.7%); freedom from type IA endoleak was 100% and patency of the renal artery was 100% at 2 years.

CONCLUSIONS

The described technique includes the use of a low-profile stent graft with a polymer ring sealing technology combined with bare renal stents that are not competing for the same room. This early experience shows that the vent technique is safe and feasible and increases the range of treatment of those patients with jAAA who are unfit for open repair and for fenestrated EVAR because of several anatomic constraints.

Anatomical Considerations and Open Surgery to Treat Juxtarenal Abdominal Aortic Aneurysms

Introduction:

Historically, the open approach to the abdominal aorta has been transperitoneal (TP). In comparison, a retroperitoneal (RP) incision exposes the lateral wall of the suprarenal aorta for clamp application and midline structures such as the duodenum and pancreas are not encountered. Proximal clamp position for open repair of juxtarenal abdominal aortic aneurysm (JR-AAA) is suprarenal, supra-superior mesenteric, or supraceliac. While RP and TP approaches have previously been compared for physiological reasons, there are currently no randomized controlled trials comparing these methods from an anatomical perspective.

Aims:

The primary aim is to examine the evidence for adopting an RP approach for JR-AAA and compare it with TP approach from an anatomical perspective. The secondary aim is to assess optimum proximal clamp position and its effect on renal function and mortality for the 2 approaches.

Methods/Design:

Literature was reviewed searching databases Medline and Embase for studies on clamp positioning in JR-AAA repair using a TP or RP approach, up to December 2017.

Conclusions:

There is no clear evidence for the optimum cross-clamp position for open repair of JR-AAAs. More proximal clamps provide adequate operative space with the possible downside of increased afterload leading to visceral and renal ischemia. Clamps placed inferior to the superior mesenteric artery allow continued bowel and hepatic perfusion with the potential to cause trauma to the adjacent aortic branches during application. As far as the optimum approach is concerned, many series show a strong trend for RP as a more proximal clamp is required. Significant numbers develop renal failure after JR-AAA repair, with most recovering fully irrespective of the clamp position.

Organ protection during aortic cross-clamping

Open surgical repair of an aortic aneurysm requires aortic cross-clamping, resulting in temporary ischemia of all organs and tissues supplied by the aorta distal to the clamp. Major complications of open aneurysm repair due to aortic cross-clamping include renal ischemia-reperfusion injury and postoperative colonic ischemia in case of supra- and infrarenal aortic aneurysm repair. Ischemia-reperfusion injury results in excessive production of reactive oxygen species and in oxidative stress, which can lead to multiple organ failure. Several perioperative protective strategies have been suggested to preserve renal function during aortic cross-clamping, such as pharmacotherapy and therapeutic hypothermia of the kidneys. In this chapter, we will briefly discuss the pathophysiology of ischemia-reperfusion injury and the preventative measures that can be taken to avoid abdominal organ injury. Finally, techniques to minimize the risk of complications during and after open aneurysm repair will be presented.

Juxtarenal Aortic Aneurysm Repair

Juxtarenal aortic aneurysm (JRAA) is an unusual, but not rare, pattern of aneurysmal disease of the abdominal aorta in which dilatation extends up to, but does not involve, the renal arteries. The objective of this report was to retrospectively analyze experience with JRAA repair at a tertiary referral center over a 5-year period. From November 1990 through December 1995, 12 consecutive patients underwent repair of JRAA by a single surgeon. There were six men and six women, ranging in age from 65 to 82 years (mean = 77 +2 years). All patients underwent preoperative imaging by aortography, ultrasound, or computed transaxial tomographic (CTT) scanning. Mean aneurysm diameter was 6.6 ± 0.3 cm. Three of the aneurysms were ruptured; however, the rupture was contained within the retroperitoneum and hemodynamic stability was maintained. Eleven aneurysms were approached transperitoneally and one retroperitoneally. Aortic clamping was at the suprarenal level in seven instances and at the supraceliac level in five instances. The left renal vein was divided to facilitate exposure in three instances. Warm renal ischemia time was 27 ± 2 minutes. Eight straight and four bifurcation grafts were placed. All patients survived 30 days. Preoperative creatinine was 1.2 ± 0.1 mg/dL. Creatinine peaked on postoperative day 4 at 1.6 ± 0.2 mg/dL and was 1.5 ± 0.3 mg/dL on postoperative day 10. In no instance was temporary dialysis necessary in the postoperative period, nor did chronic renal failure occur. Postoperative CTT scanning in one patient presenting with a ruptured JRAA revealed an infarcted and nonfunctioning left kidney. In the three patients in whom the left renal vein was divided, mean creatinine was 1.1 ± 0.1 mg/dL preoperatively and 0.9 ± 0.2 mg/dL at discharge. JRAA repair can be safely performed by aortic clamping at the suprarenal and supraceliac level. These maneuvers are well tolerated and provide the exposure necessary to facilitate aortic anastomosis at the juxtarenal level.

Management of Juxtarenal Aortic Aneurysms and Occlusive Disease with Preferential Suprarenal Clamping Via a Midline Transperitoneal Incision: Technique and Results

Surgical management of juxtarenal aortic (JR-Ao) aneurysms and occlusive disease may include supraceliac aortic clamping, a retroperitoneal approach, or medial visceral rotation. The authors report their results using preferential direct suprarenal aortic clamping via a midline transperitoneal incision. Between July 1, 1992, and July 31, 2001, they treated 58 patients with JR-Ao disease (44 aneurysmal, 14 occlusive) via a midline incision without medial visceral rotation. Preferential suprarenal aortic clamping was used in 53 cases (42 proximal to both renal arteries, 11 proximal to the left renal artery only) and supraceliac or supramesenteric clamping in 5 cases when there was insufficient space for an aortic clamp between the superior mesenteric artery and renal arteries. This strategy avoided mesenteric ischemia associated with supraceliac clamping in the majority of cases and afforded better exposure of the right renal artery than obtainable with a left retroperitoneal approach or medial visceral rotation. Eleven patients underwent concomitant renal revascularization. Critical adjuncts included the following: (1) selective left renal vein (LRV) division if the vein stump pressure was <35 mm Hg (suggesting sufficient renal venous collaterals existed), (2) bilateral renal artery occlusion during aortic clamping to prevent thromboembolism, (3) flushing of aortic debris before restoring renal perfusion, and (4) routine administration of perioperative intravenous mannitol and renal-dose dopamine. Patients with type IV thoracoabdominal aneurysms, ruptured aneurysms, or JR-Ao disease approached via a retroperitoneal incision (severely obese patients, re-do aortic surgery) were excluded. No patients died or required dialysis during their hospital stay. The LRV was divided in 12 (21%) cases and reanastomosed in 2 cases (elevated stump pressures). The average suprarenal clamp time was 26 minutes (range, 10–60). Postoperative serum creatinine remained >0.5 ng/dL above baseline in 3 (5%) patients. These results support suprarenal aortic clamping with a midline transperitoneal incision as the optimal strategy for treating juxtarenal aortic aneurysms and occlusive disease. The authors believe that selective left renal vein division enhances juxtarenal aortic exposure, and routine administration of renal protective agents, along with occlusion of both renal arteries during suprarenal aortic clamping, are critical adjuncts in performing these operations.

Fenestrated and Chimney Technique for Juxtarenal Aortic Aneurysm: A Systematic Review and Pooled Data Analysis

Juxtarenal aortic aneurysms (JAA) account for approximately 15% of abdominal aortic aneurysms. Fenestrated endovascular aneurysm repair (FEVAR) and chimney endovascular aneurysm repair (CH-EVAR) are both effective methods to treat JAAs, but the comparative effectiveness of these treatment modalities is unclear. We searched the PubMed, Medline, Embase, and Cochrane databases to identify English language articles published between January 2005 and September 2013 on management of JAA with fenestrated and chimney techniques to conduct a systematic review to compare outcomes of patients with juxtarenal aortic aneurysm (JAA) treated with the two techniques. We compared nine F-EVAR cohort studies including 542 JAA patients and 8 CH-EVAR cohorts with 158 JAA patients regarding techniques success rates, 30-day mortality, late mortality, endoleak events and secondary intervention rates. The results of this systematic review indicate that both fenestrated and chimney techniques are attractive options for JAAs treatment with encouraging early and mid-term outcomes.

Survival after repair of pararenal and paravisceral abdominal aortic aneurysms

OBJECTIVE

The objective of this study was to review our 27-year clinical experience with open proximal abdominal aortic aneurysm repairs, with a focus on long-term survival.

METHODS

A retrospective cohort study was undertaken of all patients who underwent proximal abdominal aortic aneurysm repair between 1986 and 2013 at a tertiary care referral center. Demographics, operative variables, complications, and 30-day mortality were analyzed. Postoperative acute kidney injury was analyzed by the RIFLE (Risk, Injury, Failure, Loss, End-stage renal disease)/Acute Kidney Injury Network criteria. Long-term survival was assessed through review of electronic medical records and the Social Security Death Index. Associations between demographics and complications were investigated to determine predictors of long-term survival.

RESULTS

The study identified 245 patients. Mean age was 71 years (range, 38-92 years); 69% were men, and 88% were white. Aneurysm type was juxtarenal in 127 patients (52%), suprarenal in 68 patients (28%), and type IV thoracoabdominal in 50 patients (20%). In-hospital mortality was 3.3% (eight patients), and 30-day mortality was 2.9% (seven patients). At least one major complication occurred in 64% of the patients, which included the following: acute kidney injury, 60% (persistent acute kidney injury at discharge, however, was 28%, and hemodialysis at discharge was 1.6%); major pulmonary complications, 22%; myocardial infarction, 4%; visceral ischemia, 2%; and paraplegia, 0.5%. Median follow-up was 54 months. Kaplan-Meier survival estimates were 70% at 5 years and 43% at 10 years. Variables associated with poorer survival included congestive heart failure (hazard ratio [HR], 3.5; P < .001), chronic obstructive pulmonary disease (HR, 1.8; P < .002), and increased aneurysm size at presentation (HR, 1.1; P < .013). Persistent stage 3 acute kidney injury was associated with poor long-term survival.

CONCLUSIONS

Open surgical repair of proximal abdominal aortic aneurysms can be performed with low mortality. Acute kidney injury is the most frequent complication, but the need for hemodialysis at discharge is low. Long-term survival is favorable. These data should assist in establishing benchmarks for endovascular repair of complex proximal abdominal aortic aneurysms.

Experiences of Surgical Treatment for Juxtarenal Aortic Occlusion

Purpose:

To evaluate the outcomes of juxtarenal aortic occlusion (JRAO), a review of 15 patients who underwent aortic bypass replacement following aortorenal thrombectomy, especially focusing on the safety of suprarenal aortic clamping or transient aortic compression, was undertaken.

Materials and Methods:

During the period of June 2001 to November 2012, 15 patients with JRAO (chronic 10, acute 5) were analyzed retrospectively. JRAO with combined stenosis of the renal artery was found in 2 patients, renal artery thrombus in 8 patients, and normal in 5 patients.

Results:

All patients were males. Mean age was 61.7±11.2 years. There were 14 aortobifemoral bypass grafting and 1 aortobiiliac bypass grafting. Six Dacron and 9 PTFE artificial Y-grafts were implanted to the aorta with end-to-end anastomosis in the proximal aorta. Suprarenal aortic clamping was performed in 7 patients, supraceliac clamping in 2 patients, and transient aortic compression in 6 patients. There were 13 cases with aortic clamping time <10 minutes and 2 cases with >10 minutes. Thrombectomy of the aorta and renal artery was performed in 10 (66.7%) patients. There were no operative mortality cases. The perioperative morbidity rate was 26.7% (4/15). Preoperative renal function was impaired in four patients. The renal functions of these cases were recovered postoperatively.

Conclusion:

Aortic bypass replacement following aortorenal thrombectomy with suprarenal aortic clamping or transient aortic compression for JRAO is the optimal treatment. It is important to focus on short renal ischemic time during suprarenal aortic clamping for prevention of renal damage. It provides unmatched perioperative and long-term results.

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

The purpose of this study was to seek factors predicting outcome after open surgical repair of juxtarenal abdominal aortic aneurysms (AAAs). From a series of 733 patients treated for AAAs, 92 patients underwent elective conventional open repair with suprarenal clamping. We assessed postoperative cardiorespiratory and renal morbidity and mortality and survival at 1, 3, and 5 years. One patient (1.1%) died after an acute myocardial infarction. Postoperative complications including myocardial infarction and renal failure arose in 22 patients (23.9%). Significant predicting factors of renal failure were a preoperative creatinine clearance ≤ 40 mL/min ( p = .03) and female sex ( p = .004). Kaplan-Meier survival analysis showed an overall survival rate of 98.9% at 1 year and 88.6% at 3 and 5 years. In patients carefully selected by preoperative imaging criteria to undergo open juxtarenal AAA repair, appropriate intraoperative management guarantees a good immediate postoperative outcome.

Total laparoscopic repair of abdominal aortic aneurysm with short proximal necks

With the development of endovascular aneurysm repair, abdominal aortic aneurysms with short infrarenal necks (< or =10 mm, AAASN) are considered juxtarenal aneurysms. Minimally invasive treatment consists of hybrid procedures or fenestrated endografts. We present our experience with direct aortic repair for AAASN performed via a total laparoscopic approach. Data are expressed as median values with extremes. From February 2002 to December 2007, 32 patients had total laparoscopic AAASN repair. Length of the infrarenal aortic neck was 5 mm (0-10). Median age of the 29 men and three women was 70 years (range 50-84). Nine patients presented with preoperative grade 1 renal insufficiency (28.1%). The procedure was totally laparoscopic in 30 patients (93.7%). Aortic approaches included left retrorenal (n = 24) and transperitoneal left retrocolic (n = 8) exposures. Median operative and clamping times were 270 (range 215-410) and 83 (range 36-147) min, respectively. Aortic clamping was suprarenal in 14 cases (43.7%), with suprarenal clamping time of 24 min (range 9-37). Median blood loss was 850 mL (range 215-2,400). Thirty-day mortality was 3.1% (one patient died from myocardial infarction). Two patients presented with severe systemic complications (6.4%, postoperative coagulopathy with hemorrhagic syndrome, pneumopathy). Seventeen patients developed mild or moderate systemic nonlethal complications (53.1%): transient renal insufficiencies (n = 12), grade 1 ischemic colitis (n = 1), surrenal insufficiency (n = 1), myocardial ischemia (n = 1), and cardiac arythmia (n = 2). One patient was reoperated for an intestinal obstruction. Liquid diet was reintroduced after 1 day (range 1-13). Most patients were ambulatory by day 3 (range 2-17). Median lengths of stay were 48 hr (range 12-552) in the intensive care unit and 10 days (range 4-37) in the hospital. With a median follow-up of 27 months (range 1-50), 28 patients are alive, with complete recovery without graft anomalies. Three patients died, from pneumopathy (n = 1) and carcinoma (n = 2), respectively, at 29, 19, and 44 months' follow-up. Two patients presented stable juxta-renal aortic dilation <35 mm. Total laparoscopic juxtarenal AAA repair is feasible and worthwhile for patients with AAASN. Short- and midterm results match well with those of open surgery. Total laparoscopic repair in AAASN reduces the trauma of extensive surgical approaches. Based on these encouraging early results, we elected to perform laparoscopy whenever possible in good surgical risk patients with AASN.

Repair of a pararenal abdominal aortic aneurysm with bilateral renal artery stenosis using a rapid infusion pump for renal perfusion: report of a case

A 73-year-old man with a history of hypertension and drug-induced hepatitis underwent surgical treatment of an enlarging pararenal abdominal aortic aneurysm (PRAAA) with bilateral renal artery stenosis, found on enhanced computed tomography (CT). His preoperative renal function was normal. We divided the right renal artery and used a 6-mm expanded polytetrafluoroethylene (ePTFE) tube graft for the anastomosis. Renal artery perfusion was achieved by a rapid infusion pump set at 200 ml/min. The left renal artery was reconstructed and perfused in the same way. The abdominal aorta was cross-clamped just distal to the superior mesenteric artery and a Y-graft was anastomosed. The ePTFE grafts were connected to the Y-graft and bilateral renal artery circulation was re-established. The renal ischemic time was 1 h 25 min and the urine output during reconstruction was 80 ml. Postoperatively, his serum blood urea nitrogen and serum creatinine levels increased slightly, but normalized within 3 days. This case report shows that this method of renal artery perfusion could prove useful for complex renal artery reconstructions.

Effects of thoracic and hiatal clamping in repair of ruptured abdominal aortic aneurysms

The purpose of this study was to determine the effects of hiatal and thoracic clamping on postoperative outcome and morbidity and factors affecting mortality and morbidity. The records of 102 patients who had undergone ruptured abdominal aortic aneurysm repair between 1993 and 2005 were evaluated retrospectively. Hiatal clamping and thoracic clamping were performed in 72 patients and 30 patients, respectively. Postoperative complications and survival were evaluated comparatively between the two groups by univariate and multivariate statistical analyses. Overall mortality and hospital mortality rates were 63 (61.8%) and 24 (23.5%) patients, respectively; and there was no difference between the two groups. Postoperative respiratory complications, gastrointestinal complications, and blood requirement were higher in the thoracic clamping group. Preoperative shock and renal ischemia time (>30 min) were found to be significant predictors of hospital mortality. Postoperative renal failure was the only independent postoperative predictor of mortality. In the follow-up period, cardiac event was an independent predictor of late mortality. If hospital mortalities were excluded, 5-year and 10-year cumulative survivals were 57.82 +/- 5.85% and 38.16 +/- 6.97%, respectively. Cross-clamp level did not have a significant effect on long-term survival. Although both thoracic and hiatal clamping had no effect on mortality, postoperative respiratory complications, blood requirement, and intestinal ischemia were more pronounced in patients operated with thoracic clamping. Hiatal clamping is preferable for a safe postoperative period.

Open Repair of Pararenal Aortic Aneurysms: Operative Management, Early Results, and Risk Factor Analysis

Surgical treatment of pararenal aortic aneurysms, if compared to open surgical repair of infrarenal aneurysms, is technically more demanding and characterized by problems related to organ ischemia. To better define challenges, risks, and results, we analyzed our experience with the treatment of pararenal aortic aneurysms. Between January 1993 and March 2005, 119 consecutive patients underwent surgery for pararenal aneurysms at our institution. A prospective analysis of results was performed. According to their localization, we treated 85 juxtarenal aneurysms and 34 suprarenal aneurysms. One hundred and three patients underwent primary repair of an atherosclerotic aneurysm, four patients underwent surgical repair of an anastomotic pseudoaneurysm, and eight patients underwent correction of an aneurysm of the pararenal aorta proximal to a previous infrarenal anastomosis. Four patients underwent emergency operation for a ruptured aneurysm. In the juxtarenal aneurysm group, the 30-day mortality rate was 4.7% (4/85) including three patients with ruptured aneurysm. In the suprarenal aneurysm group, the 30-day mortality rate was 2.9% (1/34). Preoperative renal insufficiency was present in 16 patients, respectively in 7 patients with juxtarenal aneurysms and in 9 patients with suprarenal ones. In 22 patients, we registered a transient increase in creatinine levels with return to baseline levels by discharge. Four patients required long-term dialysis. In three patients, a short period of dialysis was required. Clamping time longer than 30 min was associated with a higher risk of transient postoperative deterioration of renal function (p = 0.0073). Preoperative renal insufficiency was associated with a higher risk of persistent postoperative deterioration of renal function (p < 0.0001). Morbidity and mortality of elective surgery for pararenal aneurysms is acceptable. One of the main risks of this surgery is renal morbidity. Preoperative renal insufficiency and long periods of renal ischemia are associated with a higher risk of postoperative deterioration of renal function that is often, but not always, reversible. Nowadays, pararenal aneurysm repair is a safe procedure, especially if performed electively.

Factors affecting outcomes of open surgical repair of pararenal aortic aneurysms: A 10-year experience

PURPOSE

Few large series document surgical outcomes for patients with pararenal abdominal aortic aneurysms (PAAAs), defined as aneurysms including the juxtarenal aorta or renal artery origins that require suprarenal aortic clamping. No standard endovascular alternatives presently exist; however, future endovascular branch graft repairs ultimately must be compared with the gold standard of open repair. To this end, we present a 10-year experience.

METHODS

Between 1993 and 2003, 3058 AAAs were repaired. Perioperative variables, morbidity, and mortality were retrospectively assessed. Renal insufficiency was defined as a rise in the concentration of serum creatinine by > or = 0.5 mg/dL. Factors predicting complications were identified by multivariate analyses. Morbidity and 30-day mortality were evaluated with multiple logistic regression analysis.

RESULTS

Of a total of 3058 AAA repairs performed, 247 were PAAAs (8%). Mean renal ischemia time was 23 minutes (range, 5 to 60 minutes). Cardiac complications occurred in 32 patients (13%), pulmonary complications in 38 (16%), and renal insufficiency in 54 (22%). Multivariate analysis associated myocardial infarction with advanced age (P = .01) and abnormal preoperative serum creatinine (>1.5 mg/dL) (P = .08). Pulmonary complications were associated with advanced age (P = .03), renal artery bypass (P = .02), increased mesenteric ischemic time (P = .01), suprarenal aneurysm repair (P < .0008), and left renal vein division (P = .01). Renal insufficiency was associated with increased mesenteric ischemic time (P = .001), supravisceral clamping (P = .04), left renal vein division (P = .04), and renal artery bypass (P = .0002), but not renal artery reimplantation or endarterectomy. New dialysis was required in 3.7% (9/242). Abnormal preoperative serum creatinine (>1.5 mg/dL) was predictive of the need for postoperative dialysis (10% vs 2%; P = .04). Patients with normal preoperative renal function had improved recovery (93% vs 36%; P = .0002). The 30-day surgical mortality was 2.5% (6/247) but was not predicted by any factors, and in-hospital mortality was 2.8% (7/247). Median intensive care and hospital stays were 3 and 9 days, respectively, and longer stays were associated with age at surgery (P = .007 and P = .0002, respectively) and any postoperative complication.

CONCLUSIONS

PAAA repair can be performed with low mortality. Renal insufficiency is the most frequent complication, but avoiding renal artery bypass, prolonged mesenteric ischemia time, or left renal vein transection may improve results.

Acute renal failure in the critically ill

PURPOSE OF REVIEW

Acute renal failure occurs frequently in hospitalized patients and is associated with significant morbidity and mortality. An effort to better understand the epidemiology and pathophysiology of this disease will hopefully lead to improvement in patient outcomes. Considerable effort has been expended to develop techniques to prevent acute renal failure or to facilitate its resolution. In this review we attempt to summarize some of these recent advances.

RECENT FINDINGS

Attempts have been made to clearly define acute renal failure. Among the available pharmacologic agents, current evidence suggests that with the possible exception of radio-contrast-induced acute renal failure, no drugs are capable of preventing the condition or hastening its recovery. Advances in techniques and understanding of how to best provide renal replacement therapy appear to have improved patient outcomes and several newer treatments are under preclinical evaluation and may hold promise for the future.

SUMMARY

Preventing acute renal failure, improving clinical outcomes of the condition and attempts to hasten renal recovery have all been very attractive but difficult propositions. Recent efforts to explore the underlying pathophysiology and insight into mechanisms leading to acute renal failure have triggered investigators to evaluate novel therapeutic agents and enhance existing dialytic techniques. These hold great promise for improving patient outcomes in the near future.

Effects of intrarenal administration of the cox-2 inhibitor parecoxib during porcine suprarenal aortic cross-clamping

The aim of this study was to investigate the effects of intrarenal administration of the cyclooxygenase-2 inhibitor parecoxib during suprarenal aortic cross-clamping. In a prospective, controlled, blinded, randomized manner, 16 anesthetized and mechanically ventilated pigs were instrumented to measure systemic and right kidney hemodynamics, oxygen exchange, and metabolism. During 45 min of suprarenal aortic cross-clamping, animals received 40 mg of parecoxib (n = 8) or vehicle (n = 8) infused continuously into the right renal artery. Hemodynamic and metabolic data, right kidney venous blood, as well as urine samples were obtained before clamping, as well as before and 75 and 195 min after declamping. Clamping transiently increased mean arterial pressure in both groups. Systemic and renal blood flow did not differ between the pre- and postclamping measurements or between groups. Parecoxib attenuated the otherwise significant fall in right kidney creatinine clearance (controls: from 45 [7;111] to 17 [9;22] mL/min; parecoxib: from 39 [3;59] to 27 [11;45] mL/min, P = 0.039 and P = 0.297, respectively versus before clamping, P = 0.021 versus controls at 195 min) and prevented the impairment of renal lactate balance observed in the control group (controls: from 0.5 [-0.8;3.5] to 0.2 [-0.2;0.6] mumol/kg/min; parecoxib: from 0.6 [-1.0;2.0] to 0.4 [-1.2;0.6] mumol/kg/min, P = 0.038 and P = 0.285, respectively, versus before clamping). In conclusion, intrarenal parecoxib infusion beneficially influenced kidney function in this clinically relevant model of suprarenal aortic cross-clamping.

Aorto-left renal artery bypass as an adjunct to suprarenal abdominal aortic aneurysm repair

Renal ischemia remains a vexing issue in the repair of suprarenal abdominal aortic aneurysms (SR-AAAs). Multiple reconstruction methods have been described, including fish-mouth anastomoses, renal artery reimplantation, and aortorenal interposition grafts. We present an alternative method of SR-AAA repair that minimizes renal ischemia time. We describe our approach in two patients with SR-AAAs. Both patients had normal preoperative renal function. Maximal aneurysm diameters were 6.0 and 7.4 cm. In each case, the abdominal aorta was exposed via the retroperitoneal approach and the supraceliac aorta was dissected from the surrounding tissue. A partially occluding side-biting aortic clamp was placed at this level to facilitate placement of a synthetic 6 mm interposition graft that was sewn in an end-to-side fashion to the suprarenal aorta first. These grafts were then sewn end-to-end to the left renal artery, completing the aorto-left renal bypass. Left renal ischemia times were 12 and 14 min. The aneurysm was then repaired with a beveled proximal anastomosis, accommodating the right renal artery orifice. Both patients had minimal postoperative renal dysfunction, with peak creatinine levels of 1.9 and 1.4 mg/dl. At discharge, both patients had a creatinine level of 1.1 mg/dl. Urinary output remained normal throughout the hospital stays, and neither patient required dialysis. Retroperitoneal aortic exposure with preliminary aorto-left renal artery bypass is an effective method of treating SR-AAAs. Proximal anastomosis can be done with less urgency and minimal right renal ischemia, by revascularizing the left kidney first.

Critical Analysis of Outcome Determinants Affecting Repair of Intact Aneurysms Involving the Visceral Aorta

Visceral (mesenteric and/or renal) ischemia/reperfusion phenomena likely contribute to the greater operative risk associated with pararenal and lower thoracoabdominal aortic aneurysm (TAA) repair. To differentiate the relative adverse effects of aortic clamp level, visceral ischemic duration, and various pre- and perioperative factors shared with infrarenal aneurysm patients, a comparative analysis of early and late outcomes after open repair of intact infrarenal and visceral aortic aneurysms was undertaken. A retrospective review of our university experience from 1993-1999/2002 revealed 549 patients (mean age 70 +/- 8 years, 11% female) undergoing open repair of intact, degenerative aneurysms of the infrarenal (n = 391, 71%), juxtarenal (n = 78, 14%), suprarenal (n = 35, 7%), and type IV (n = 40, 7%) and type III (n = 5, 1%) TAA segments. All pararenal aneurysms required suprarenal (SR) or supravisceral (SV, above celiac or superior mesenteric artery) clamp placement. Concomitant renal reconstruction was done in 30% of visceral aortic and 3% of open infrarenal aneurysm repairs. Thirty-day adverse outcomes [death, renal failure (creatinine 2 x baseline or new dialysis), visceral (bowel, hepatic, renal, spinal cord, multiple organ dysfunction), and nonvisceral (cardiac, pulmonary, procedural) complications] were analyzed relative to patient and operative factors using univariate comparisons and multivariate stepwise logistic regression. Perioperative mortality rates varied significantly between aneurysm locations (infrarenal 2.1%, juxtarenal 2.6%, suprarenal 11.4%, TAA 13.3%; p < 0.01) and for clamp locations (infrarenal 2.1%, SR 3.0%, SV 10.8 %; p < 0.01) but were not different between juxtarenal (1.8% vs. 4.4 %) and SR (9.1% vs. 12.5%) aneurysms requiring SR or SV clamping, respectively. Visceral ischemic time (VIT) during SR or SV clamping, and not clamp location, was the only independent predictor of operative mortality [odds ratio (OR) = 10.8, 95% confidence interval (CI) 4-29]. Sensitivity analyses revealed VIT > 32 min to be the strongest predictor of early death. Visceral complication or renal failure affected 34% and 23% of visceral aortic (5% dialysis) and 7% and 5% (1% dialysis) of infrarenal repairs, respectively. VIT > 32 min, SV clamp placement, diabetes, and inflammatory aneurysm repair were each predictive of visceral complications and/or renal failure. Five-year survival rate was similar after visceral aortic (70%) and infrarenal (75%) repairs but negatively impacted only in patients with prior infrarenal abdominal aortic aneurysm repair and recurrent aneurysms (OR = 2.8, 95% CI 1.2-6.9). The high incidence of early adverse outcomes following repair of pararenal and lower thoracoabdominal aneurysms is primarily associated with excessive periods of renal and/or gut ischemia during visceral aortic clamp placement. However, nearly equivalent early and late survival was seen for visceral aortic and infrarenal repairs when VIT < 32 min was achieved.

Estudo da morfologia renal após a oclusão da aorta abdominal infra-renal em ratos

OBJETIVO: Relacionar as alterações morfológicas renais sob microscopia de luz, de ratos submetidos à oclusão de aorta, em modelo que simule a condição clínica de reparação cirúrgica de um aneurisma de aorta abdominal. MÉTODO: Ratos Wistar (N = 60), machos pesando entre 200 e 250g, foram distribuídos em três grupos: I (simulado); II (isquemia); III (isquemia + reperfusão); e cada grupo redistribuído em dois subgrupos: A (30 min); B (60 min). Foi realizada isquemia utilizando clamp vascular (8mm) na aorta abdominal infra-renal de acordo com o grupo estudado. Ao final de cada experimento os animais foram mortos e realizada análise histológica renal cortical e medular (descritiva e morfométrica) através de metodologia convencional (parafina-hematoxilinaeosina). A análise semiquantitativa de lesão tubular e intersticial foi realizada de acordo com o índice de lesão tubular e índice de lesão intersticial. Para a análise estatística foram aplicados os seguintes testes: Mann-Whitney, Kruskal-Wallis, Comparações múltiplas (p < 0,001). RESULTADOS: Observou-se no grupo III alterações histológicas tubulares e intersticiais significantes com relação aos outros grupos (p < 0,001). CONCLUSÕES: A oclusão da aorta abdominal infra-renal em ratos está associada a lesões estruturais renais tanto tubulares quanto intersticiais principalmente na fase de reperfusão.

The Management of Abdominal Aortic Aneurysms in Patients with Concurrent Renal Impairment

INTRODUCTION

Patients with concurrent renal impairment and abdominal aortic aneurysms present a significant challenge in terms of pre-operative, intra-operative and post-operative management. This aim of this review was to determine the risks of surgery in this patient group and determine whether any clear management strategies exist to enhance their clinical management.

METHODS

Systematic review of published literature giving details of the outcome of open or endovascular abdominal aortic aneurysm repair in patients with pre-operative renal impairment. Papers concerning the management of post-operative acute renal failure in patients with normal pre-operative renal function has not been included.

RESULTS

There is little data regarding patients with end-stage renal failure and AAA although these patients appear to have a high peri-operative mortality rate. In contrast, those with renal impairment do not have a significantly higher mortality rate than those with normal renal function, rather they have a higher risk of complications associated with surgery and may require more intensive post-operative organ system support than normal patients. Many have a transient deterioration in renal function in the immediate peri-operative period that will resolve. In the case of patients with ruptured AAA, it is not clear whether pre-operative renal impairment affects mortality.

Activation of fibrinolytic pathways is associated with duration of supraceliac aortic cross-clamping

PURPOSE

The cause of the coagulopathy seen with supraceliac aortic cross-clamping (SC AXC) is unclear. SC AXC for 30 minutes results in both clotting factor consumption and activation of fibrinolytic pathways. This study was undertaken to define the hemostatic alterations that occur with longer intervals of SC AXC.

METHODS

Seven pigs underwent SC AXC for 60 minutes. Five pigs that underwent infrarenal aortic cross-clamping (IR AXC) for 60 minutes and 11 pigs that underwent SC AXC for 30 minutes served as controls. No heparin was used. Blood samples were drawn at baseline, 5 minutes before release of the aortic clamp, and 5, 30, and 60 minutes after unclamping. Prothrombin time, partial thromboplastin time, platelet count, and fibrinogen concentration were measured as basic tests of hemostatic function. Thrombin-antithrombin complexes were used to detect the presence of intravascular thrombosis. Fibrinolytic pathway activation was assessed with levels of tissue plasminogen activator antigen and tissue plasminogen activator activity, plasminogen activator inhibitor-1 activity, and alpha2-antiplasmin activity. Statistical analysis was performed with the Student t test and repeated measures of analysis of variance.

RESULTS

Prothrombin time, partial thromboplastin time, and platelet count did not differ between groups at any time. Fibrinogen concentration decreased 5 minutes (P =.005) and 30 minutes (P =.006) after unclamping in both SC AXC groups, but did not change in the IR AXC group. Thrombin-antithrombin complexes increased in both SC AXC groups, but were not significantly greater than in the IR AXC group. SC AXC for both 30 and 60 minutes produced a significant increase in tissue plasminogen activator antigen during clamping and 5 minutes after clamping. This increase persisted for 30 and 60 minutes after clamp release in the 60-minute SC AXC group. Tissue plasminogen activator activity, however, increased only in the 60-min SC AXC group during clamping (P =.02), and 5 minutes (P =.05) and 30 minutes (P =.06) after unclamping, compared with both control groups.

CONCLUSIONS

Thirty and 60 minutes of SC AXC results in similar degrees of intravascular thrombosis and fibrinogen depletion. Although SC AXC for both 30 and 60 minutes leads to activation of fibrinolytic pathways, only 60 minutes of SC AXC actually induces a fibrinolytic state. Fibrinolysis appears to be an important component of the coagulopathy associated with SC AXC, and is related to the duration of aortic clamping.

CLINICAL RELEVANCE

The coagulopathy frequently associated with thoracoabdominal aortic aneurysm repair is thought to revolt visceral ischemia-reperfusion. The nature of this coagulopathy is controversial. The current study demonstrates that the major hemostatic alteration associated with supraceliac aortic cross-clamping is activation of fibrinolytic pathways. The magnitude of this fibrinolytic response is directly related to the duration of supraceliac aortic occlusion. Future efforts to treat this coagulopathy may well include judicious use of autofibrinolytic agents.

Experience of an abdominal aortic aneurysm in a patient having crossed ectopia with fusion anomaly of the kidney

We report a case of surgically treated abdominal aortic aneurysm (AAA) in a patient having crossed ectopia with fusion anomaly of the kidney. One artery from the abdominal aorta above the aneurysm supplies the right kidney while three renal arteries (two from the aneurysm itself and one from the left common iliac artery) supply the crossed ectopic kidney. Preoperative imaging to define the arterial and collecting systems along with a detailed planning of the operation is essential to prevent ischemic renal injury as well as ureteral injury during AAA repair.

Regional hypothermia reduces mucosal NF-kappaB and PMN priming via gut lymph during canine mesenteric ischemia/reperfusion

BACKGROUND

Mesenteric ischemia/reperfusion (I/R) activates pro-inflammatory mediators that exacerbate gut reperfusion injury and prime circulating neutrophils that cause remote organ injury. We have shown that regional intraischemic hypothermia protects the intestinal mucosa during I/R in rats. In this study, we examined the effects of regional hypothermia on I/R-induced transvascular protein clearance, NF-kappaB DNA binding activity, and polymorphonuclear neutrophil (PMN) priming via gut lymph in a canine mesenteric lymphatic fistula model.

MATERIALS AND METHODS

Conditioned dogs underwent 60 min of mesenteric ischemia, with or without regional intraischemic hypothermia, and 3 h reperfusion. A mesenteric lymphatic fistula model was used to measure transvascular protein clearance and harvest lymph. Biopsies of distal ileum were obtained at baseline and 0, 180 min of reperfusion for NF-kappaB DNA binding activity using electrophoretic mobility shift assay (EMSA). A kinetic spectrophotometric assay was used to determine fMLP stimulated PMN superoxide production after priming by gut lymph obtained at baseline and 180 min reperfusion.

RESULTS

Transvascular protein clearance increased during reperfusion compared to baseline, and hypothermia had no significant effect on this I/R-induced protein clearance. NF-kappaB activity increased three-fold at the end of ischemia and hypothermia prevented this early activation. PMN superoxide production increased 19-fold during I/R (0.06 +/- 0.04 versus 1.14 +/- 0.50 nmol O(2), P < 0.05), but only 2.5-fold during I/R + hypothermia (0.28 +/- 0.09 versus 0.70 +/- 0.32 nmol O(2), P = 0.2).

CONCLUSIONS

Regional intraischemic hypothermia prevented early intestinal NF-kappaB activation, partially abrogated PMN priming via gut lymph, but had no significant effect on increased transvascular protein clearance during mesenteric I/R in dogs.

Renal dysfunction and prolonged visceral ischaemia increase mortality rate after suprarenal aneurysm repair

BACKGROUND

Elective juxtarenal abdominal aneurysm repair has a significantly lower mortality rate than suprarenal repair. Identification of factors affecting outcome may lead to a reduction in mortality rate for suprarenal repair.

METHODS

Data were collected prospectively between 1993 and 2000 for 130 patients who underwent type IV thoracoabdominal aneurysm (TAA) repair and 44 patients who had juxtarenal aneurysm (JRA) repair. Preoperative risk factors and operative details were compared between groups and related to outcome after TAA repair (there were only two deaths in the JRA group).

RESULTS

The in-hospital mortality rate was significantly higher following TAA repair (20.0 per cent; 26 of 130 patients) than JRA repair (4.5 per cent; two of 44). Raised serum creatinine concentration was the only preoperative factor (P = 0.013) and visceral ischaemia the only significant operative factor (P = 0.001) that affected mortality after TAA repair.

CONCLUSION

JRA repair was performed with similar risks to those of infrarenal aneurysm repair. Impaired preoperative renal function was related to death following TAA repair and conservative treatment should be considered for patients with a serum creatinine level above 180 micromol/l. Reducing the duration of visceral ischaemia might improve outcome.

Atrial natriuretic peptide infusion improves ischemic renal failure after suprarenal abdominal aortic cross-clamping in dogs

OBJECTIVE

The suprarenal abdominal aortic cross-clamping during aortic aneurysm repair causes renal dysfunction after surgery. Atrial natriuretic peptide (ANP), a hormone synthesized by the cardiac atria, induces diuresis-natriuresis and increases glomerular filtration rate. Therefore, we tested the hypothesis that prophylactic ANP infusion could limit the development of acute renal failure after aortic cross-clamping.

DESIGN

Prospective, comparative, experimental study.

SETTING

Laboratory at a university hospital.

SUBJECTS

Twelve male beagle dogs (10-13 kg) with mechanical ventilation under pentobarbital anesthesia.

INTERVENTIONS

A catheter was inserted into the femoral vein, and lactated Ringer solution (10 mL/kg/hr) was administered throughout the study period. Two groups of animals were studied: the control group (n = 6), which received saline vehicle before and after suprarenal abdominal aortic cross-clamping for 1.5 hrs; and the ANP group (n = 6), which received ANP (1 microg/kg/min) for 5 hrs, starting from 10 mins before suprarenal abdominal aortic cross-clamping until the end of procedure.

MEASUREMENTS AND MAIN RESULTS

Changes in systemic and renal hemodynamics, blood gases, and renal function were measured at baseline and 1, 2, 3, 4, and 5 hrs after aortic cross-clamping. After aortic cross-clamping, urine volume, renal blood flow, and creatinine clearance significantly (p <.01) decreased, and serum creatinine concentrations significantly (p <.01) increased, but these effects were limited by continuous ANP infusion.

CONCLUSIONS

The present study shows that ANP infusion preserved renal function after suprarenal abdominal aortic cross-clamping in dogs. These results justify a trial of ANP infusion in humans during aortic aneurysm repair.

Intraischemic hypothermia differentially modulates oxidative stress proteins during mesenteric ischemia/reperfusion

BACKGROUND

Thoracoabdominal aortic aneurysm repair requires obligatory mesenteric ischemia/reperfusion (I/R), eliciting an inflammatory response resulting in gut dysfunction and remote organ injury. Therapeutic hypothermia has been advocated for organ protection (ie, brain, spinal cord, and kidneys) during extensive aortic operation, and it has also been shown to differentially modulate proinflammatory gene transcription in the central nervous system. In other I/R models, nuclear factor Kappa-B (NF-(kappa)B) and inducible nitric oxide synthase (iNOS) worsen while heme oxygenase-1 (HO-1) protects against injury. We examined the effects of regional intraischemic hypothermia on mesenteric I/R-induced mucosal injury, NF-kappaB activation, and expression of iNOS and HO-1.

METHODS

Sprague-Dawley rats underwent sham laparotomy or superior mesenteric artery occlusion for 45 minutes with or without topical hypothermia (15 degrees -20 degrees C). Intestinal epithelial permeability to (14)C inulin was assessed at 6 hours of reperfusion. In a separate set of experiments, biopsies of the ileum were obtained at 6 hours of reperfusion for: 1) mucosal histologic injury assessed by a blinded observer; 2) NF-kappaB activation by electrophoretic mobility shift assay; and 3) iNOS and HO-1 protein expression by immunoblot.

RESULTS

Mesenteric I/R significantly increased intestinal permeability to (14)C inulin, histologic injury, activation of NF-kappaB, and iNOS and HO-1 expression when compared with sham control rats. In contrast, rats treated with intraischemic topical hypothermia exhibited intestinal permeability comparable with sham control rats, and reduced histologic injury. In addition, hypothermia prevented the activation of NF-kappaB and iNOS expression, but had no effect on HO-1 expression.

CONCLUSIONS

On the basis of these observations, we conclude that therapeutically applied intraischemic hypothermia protects the gut during mesenteric I/R. In addition, hypothermia prevented NF-kappaB activation while differentially modulating expression of the oxidative stress proteins iNOS and HO-1 in response to mesenteric I/R.

Renal function after aortic stent-grafting including coverage of renal arterial ostia

Considerable experience has been gained with endoluminal stent-graft techniques for the treatment of infrarenal aortic aneurysms. The inclusion of uncovered suprarenal stents eases the treatment of cases with a short, angulated, or bottlenecked proximal neck. However, few data have been published on the effect of a stent-graft crossing renal artery ostia on long-term renal function. We therefore retrospectively analyzed the influence of intra-aortic stent-grafts, including suprarenal fixation on long-term renal function. Thirty-nine patients who received a Gianturco Z stent across renal artery ostia as part of a made-to-measure stent-graft treating an infrarenal aortic aneurysm were evaluated at 6 (all patients) and 30 months (15 patients) after surgery. Renal function evaluation included serum creatinine level, creatinine clearance using the Cockcroft-Gault formula, and renal tomography. Initial technical success was achieved in all patients. There were no minor or major complications. Mean serum creatinine levels were 1.16 +/- 0.25, 1.12 +/- 0.28, and 1.24 +/- 0.25 mg/dL before and 6 and 30 months after endoluminal stent-graft performance, respectively (P = not significant [NS]). Mean creatinine clearances were 60.3 +/- 19.7, 63 +/- 23, and 60.6 +/- 17.5 mL/min before and 6 and 30 months after endoluminal stent-graft performance, respectively (P = NS). Only two patients (5%) had a decrease in glomerular filtration rate greater than 20% at 6 months. Both patients had renal insufficiency before endovascular grafting. Renal function was stable in all patients at 30 months' follow-up. We suggest that renal function is unaffected by coverage of renal arterial ostia with Gianturco Z stents.

Renal perfusion during thoracoabdominal aortic operations: cold crystalloid is superior to normothermic blood

BACKGROUND

Renal failure remains a common complication of thoracoabdominal aortic aneurysm repair. The purpose of this randomized clinical trial was to compare two methods of selective renal perfusion--cold crystalloid perfusion versus normothermic blood perfusion--and determine which technique provides the best kidney protection during thoracoabdominal aortic aneurysm repair.

METHODS

Thirty randomized patients undergoing Crawford extent II thoracoabdominal aortic aneurysm repair with left heart bypass had renal artery perfusion with either 4 degrees C Ringer's lactate solution (14 patients) or normothermic blood from the bypass circuit (16 patients). Acute renal dysfunction was defined as an elevation in serum creatinine level exceeding 50% of baseline within 10 postoperative days.

RESULTS

One death occurred in each group. One patient in the blood perfusion group experienced renal failure requiring hemodialysis. Ten patients (63%) in the blood perfusion group and 3 patients (21%) in the cold crystalloid perfusion group experienced acute renal dysfunction (p = 0.03). Multivariable analysis confirmed that the use of cold crystalloid perfusion was independently protective against acute renal dysfunction (p = 0.02; odds ratio, 0.133).

CONCLUSIONS

When using left heart bypass during repair of extensive thoracoabdominal aortic aneurysms, selective cold crystalloid perfusion offers superior renal protection when compared with conventional normothermic blood perfusion.

Factors affecting outcome in proximal abdominal aortic aneurysm repair

Sixty-five consecutive patients undergoing nonemergent repair of an abdominal aortic aneurysm (AAA) originating above the visceral and/or renal arteries were studied to determine operative results and identify factors influencing outcome of proximal AAA repair. Factors associated with postoperative morbidity were analyzed using multivariate analysis. There were no postoperative deaths, paraplegia/paraparesis, or symptomatic visceral ischemia. Proximal AAA repair can be accomplished with acceptable mortality. If renal artery bypass or reimplantation is anticipated, cold renal perfusion may protect against renal dysfunction. Postoperative pulmonary dysfunction can be reduced by avoiding radial division of the diaphragm.

Characterization of renal parenchymal perfusion during experimental infrarenal aortic clamping and declamping with enhanced thermodiffusion electrodes

Despite multiple previous experimental and clinical investigations, it has not been fully clarified until now whether infrarenal aortic cross-clamping (IRAC) induces a significant disturbance of renal parenchymal perfusion. Most renal cortical flow data collected thus far have been heterogenous because of inherent limitations of available measurement technology. The enhanced thermal diffusion (TD) electrode is a newly developed and previously validated prototype device that allows continuous quantification of parenchymal kidney perfusion after local probe implantation. We monitored renal perfusion during experimental IRAC with TD for the first time, thereby also evaluating the potential applicability of the method in clinical aortic surgery. IRAC (20 min) followed by sudden declamping was performed in pigs under general anesthesia (n = 14). Renal cortical blood flow (RCBF) was continuously quantified by TD, total aortic flow (TABF) and renal artery flow (RABF) were measured by ultrasonic flow probes, and parameters of systemic circulation were determined by Swan-Ganz catheter. Our results showed that kidney perfusion can be continuously quantified using TD electrodes during experimental aortic surgery in a porcine model. IRAC does not lead to a significant impairment of RCBF in young pigs as measured by TD. Renal perfusion appears to be predominantly pressure driven. Consequently, abrubt aortic declamping can bring about prolonged renal ischemia. Transfer of the TD method to RCBF monitoring during clinical aortic surgery appears to be feasible and should be investigated in selected cases.

Successful endovascular repair of juxtarenal and suprarenal aortic aneurysms with a branched stent graft

This case report describes a new technique for repairing pararenal aortic aneurysms with a transluminally placed triple-branched stent graft with sidearms extending into the superior mesenteric artery and renal arteries. Endovascular repair with the branched stent graft was attempted in two patients with a pararenal aortic Aneurysm. Stent grafting was technically successful in both patients. Although postoperative transient renal function impairment and paralytic ileus occurred in patient 2, these complications were gradually resolved in the perioperative period. A substantial shrinkage of the aneurysm was revealed by means of computed tomographic measurements in patient 1. In both patients, complete exclusion of the aneurysm and patency of the bilateral renal arteries and the superior mesenteric artery were confirmed by means of follow-up computed tomographic images at 2 years. This minimally invasive approach for pararenal aortic aneurysms appears to be a viable therapeutic option for patients who are at high risk for open surgery.

Short-term Arterial Blood Reperfusion of Normothermic Kidney in Renal Artery and Abdominal Aorta Reconstructive Surgery

OBJECTIVE

to prevent kidney injury in renal artery and juxta-renal aortic surgery. After 30 min of cross-clamping ischaemia, renal arterial inflow is temporary re-established for 3 min. The aim of the study was to retrospectively analyse the results of this original technique.

METHODS

between January 1987 and May 1999, 48 patients underwent kidney short-term arterial blood reperfusion, directly or through the Pruitt-Inahara shunt. The reperfusion was repeated every 30 min of ischaemia, whenever necessary. Fifty control patients underwent <30 min of kidney ischaemia. Patients were assessed by serum creatinine, digital angiography and radioisotope renography using technecium(99).

RESULTS

in the study group one patient developed an acute renal failure and died (2% (-95% CI: 0-11%)). In both study and control groups patients showed a similar and moderate but temporary decline in renal function, which returned to preoperative levels after 1 week.

CONCLUSIONS

the results of this study indicate that kidney short-term reperfusion may protect renal tissue from prolonged cross-clamping ischaemia (up to 100 min), also in patients considered at high risk for acute renal failure.