RETRACTED: Prevention of renal failure in patients undergoing thoracoabdominal aortic aneurysm repair

OBJECTIVE: Renal failure is a potential complication after thoracoabdominal aortic aneurysm (TAAA) repair and is a significant risk factor for postoperative mortality. We assessed the results of distal aortic perfusion and continuous volume-controlled and pressure-controlled blood perfusion of the kidneys during TAAA repair in patients with preoperative normal and impaired renal function. METHODS: Surgical repair of TAAA was performed in 279 consecutive patients (type I, n = 90; type II, 117; type III, 42; type IV, 30). In 195 patients preoperative renal function was normal; however, in 84 patients renal insufficiency was diagnosed (serum creatinine concentration [SCr], 1.4-2.0 mg/dL, n = 46; SCr, 2.0-2.5 mg/dL, n = 20; and SCr, >2.5 mg/dL, n = 18). Renal perfusion was established with catheters connected to the left-sided heart bypass. Volume flow was assessed with ultrasound, and pressure channels in the catheters enabled pressure- controlled perfusion of the kidneys. RESULTS: Selective renal artery perfusion was achieved in all patients without technical problems or complications. In each catheter, mean arterial pressure was 69 mm Hg and volume flow was 275 mL/min. During aortic cross-clamping, urine output was uninterrupted, irrespective of clamp time. Most patients demonstrated limited or moderate increase in SCr concentration. In 17 patients (6%) SCr doubled, and peaked above 3 mg/dL, but returned to baseline levels within several days. Three patients (1%) required temporary dialysis but were discharged without further need for dialysis. In general, preoperative renal impairment did not worsen. CONCLUSION: Distal aortic and selective renal blood perfusion is an effective measure to protect renal function during TAAA repair, but only if perfusion is provided with adequate volume and pressure. This technique also averts dialysis in most patients with preoperative renal failure.     

Selective visceral and renal perfusion in thoracoabdominal aneurysm repair.

OBJECTIVE: Whether or not selective visceral and renal perfusion during thoracoabdominal aortic aneurysm (TAAA) repair has a protective effect on visceral and renal function remains unknown. The aim of this study was to clarify if selective perfusion has such an effect. METHODS: From May 1982 to December 1997, 82 consecutive patients underwent TAAA repair. Patients receiving hypothermic circulatory arrest or cooling of the kidney using Ringer's lactate solution were excluded, thus 73 patients were enrolled into this study. They were divided into three groups: those in whom selective visceral and renal perfusion was performed using a roller pump (n = 41), those in whom it was performed using a centrifugal pump with a reduced heparin regimen (n = 22) and those who underwent simple aortic clamping alone (n = 10). RESULTS: Serum creatinine, total bilirubin and alanine aminotransferase levels were elevated postoperatively in patients undergoing simple cross-clamp repair, but remained almost within normal limits in patients undergoing TAAA repair with selective visceral and renal perfusion. Urine output was more in selective perfused patients than in non-perfused patients. Renal dysfunction, defined by requirement of hemodialysis or by a serum level of creatinine above 3 mg/dl, occurred in four patients (10%) of the roller pump group and in two patients (9%) of the centrifugal pump group, while in four patients (40%) of the simple cross-clamping group. CONCLUSION: Our experience suggests that selective visceral and renal perfusion has a protective effect on hepato-renal function during TAAA repair.     

Surgical repair of thoracoabdominal aortic aneurysms

Morbidity and mortality following thoracoabdominal aortic aneurysm (TAAA) repair are tremendous. Preoperative assessment is essential in detecting cardiac and pulmonary risk factors in order to reduce cardiopulmonary complications. Paraplegia and renal failure are main determinants of postoperative mortality and therefore gained substantial attention during the last decades. Left heart bypass, cerebrospinal fluid (CSF) drainage and epidural cooling have significantly reduced paraplegia rate, however, this dreadful event still occurs in up to 25% of patients undergoing type II repair. Renal failure has been partly prevented by means of retrograde aortic perfusion and cooling but renal failure still remains a significant problem. We have evaluated the effects of protective measures aiming for reduction of paraplegia and renal failure. Monitoring motor evoked potentials (MEPs) is an accurate technique to assess spinal cord integrity during TAAA repair, guiding surgical strategies to prevent paraplegia. Selective volume- and pressure controlled perfusion is a technique to continuously perfuse the kidneys during aortic cross clamping and subsequent circulatory exclusion In patients with atherosclerotic thoracoabdominal aortic aneurysms, blood supply to the spinal cord depends on a highly variable collateral system. In our experience, monitoring MEPs allowed detection of cord ischemia, guiding aggressive surgical strategies to restore spinal cord blood supply and reduce neurologic deficit: overall paraplegia rate was less than 3%. We believe that these protective measures should be included in the surgical protocol of TAAA repair, especially in type II cases. Renal and visceral ischemia can be reduced significantly by continuous perfusion during aortic cross clamping in TAAA repair. Not only sufficient volume flow but also adequate arterial pressure appears to be essential in maintaining renal function.Obviously, endovascular modalities have been successfully applied in TAAA patients, the majority of which as part of hybrid procedures. Technological innovation will eventually cause a shift from open to minimal invasive surgical repair. At present, however, open surgery is considered the gold standard for TAAA repair, especially in (relatively) young patients and patients suffering from Marfan's disease.     

Perfusion techniques for renal protection during thoracoabdominal aortic surgery

Open thoracoabdominal aortic aneurysm (TAAA) repair includes aortic clamping that interrupts antegrade blood flow to distal organs. Ischemia involving the kidneys can lead to renal failure and poor outcomes. To this end, prevention of ischemic kidney damage has led to several perfusion strategies that protect the kidneys during TAAA surgery. Options for renal perfusion include the use of passive shunts or mechanical circulatory support to deliver oxygenated blood continuously to the kidneys until normal aortic flow is re-established. An alternative approach, renal perfusion with cold crystalloid, has emerged as the preferred option of renal protection at several centers. Although there is considerable variation, several studies have demonstrated that cold crystalloid renal perfusion provides excellent protection, particularly in high-risk patients such as those with renal artery occlusive disease, preoperative renal dysfunction, or a ruptured aneurysm. Notably, recent consensus practice guidelines recommend either cold crystalloid or blood perfusion be considered for renal protection during TAAA repair. In this article, we discuss these various strategies for renal protection during TAAA repair and highlight the related technical aspects.     

Selective visceral perfusion during thoracoabdominal aortic aneurysm repair.

PURPOSE: To evaluate the effectiveness of selective visceral perfusion during repair of an thoracoabdominal aortic aneurysm (TAAA), we compared the postoperative renal and hepatic functions (blood urea nitrogen, serum creatinine, total bilirubin, glutamate pyruvate transaminase) between the two groups with and without perfusion. PATIENTS AND METHODS: We operated on 52 patients with TAAA. Among them, the visceral vessels were reconstructed in 22 patients with selective visceral perfusion and in 12 patients without perfusion. The average selective perfusion time was 49.5+/-25.5 min. in the celiac and superior mesenteric arteries and 32.8+/-18.8 min. in the renal arteries. The average perfusion flow rate per each visceral vessel was 155.4+/-97.4 ml/min. RESULTS: There were five hospital deaths. There was no significant difference between the groups in the postoperative value of four factors. The selective perfusion time for vessel reconstruction in the selective visceral perfusion group was significantly longer than the arterial clamp time for vessel reconstruction in the non-perfusion group (49.5+/-25.5 min. vs. 25.6+/-13.4 min.). CONCLUSION: Our selective visceral perfusion method is not only beneficial for organ protection, but also provides us with the necessary time to reimplant the visceral as well as intercostal or lumbar arteries.     

Hybrid approach to thoracoabdominal aortic aneurysms in patients with prior aortic surgery

OBJECTIVE: The hybrid approach to the repair of thoracoabdominal aortic aneurysm (TAAA), consisting of visceral aortic debranching with retrograde revascularization of the splanchnic and renal arteries and aneurysm exclusion using stent grafts, has been previously described and may be considered particularly appealing in high-risk patients, especially those who have undergone prior aortic surgery. This study analyzed prospectively recorded data of a series of high-risk patients with prior aortic surgery who underwent hybrid TAAA repair at our institute and contrasted the outcomes with those of a similar group of patients who underwent conventional open TAAA repair. METHODS: Between 2001 and 2006, 13 patients (12 men) with a median age of 69.6 years (range, 35 to 82 years) underwent one-stage hybrid repair of TAAA (7 type I, 2 type II, 2 type IV, and 2 aneurysms of the visceral aortic patch). These patients, the hybrid group, had a history of aortic surgery (30.7% ascending, 30.7% descending, 46.1% abdominal aortic repair, and 15.4% redo TAAA) and were at high risk for open repair. The criteria used to define these patients as high risk and to indicate the need for hybrid treatment were American Society of Anesthesiologists (ASA) class 3 or 4 associated with a preoperative forced expiratory volume in 1 second (FEV1)<50%. In all cases, we accomplished partial or total visceral aortic debranching through (1) a previous visceral artery retrograde revascularization with synthetic grafts (single bypass, customized Y or bifurcated grafts), and (2) aortic endovascular repair with one of three different commercially produced stent grafts (Cook, W.L. Gore & Assoc, and Medtronic). We analyzed the results and compared the outcomes of the hybrid group with those of a similar group of 29 patients (25 men) with a median age 65.3 years (range, 58 to 79) selected from our overall series of 246 TAAA repairs between 1988 and 2005. These 29 patients, the conventionally treated group, were selected for having had aortic surgery (22% ascending, 38% descending, 42% abdominal aortic repair, and 10.3% redo TAAA), an ASA 3 or 4, a preoperative FEV1<50%, and a conventional open repair of TAAA (10 type I, 5 type II, 4 type III, 7 type IV, and 3 aneurysms of the visceral aortic patch). RESULTS: In the hybrid group, 32 visceral bypasses were completed and endovascular TAAA repair was successful in all cases. No intraoperative deaths occurred. Perioperative mortality was 23%, and morbidity was 30.8% (renal failure in 2, respiratory failure in 1, and delayed transient paraplegia in 1). At a median follow-up of 14.9 months (range, 11 days to 59.4 months), all grafts were patent at postoperative computed tomography angiography and no aneurysm-related deaths, endoleak, stent graft migration, or morbidity related to visceral revascularization had occurred. No conventionally treated patients died intraoperatively. Perioperative mortality was 17.2% and morbidity was 44.8% (respiratory failure in 7, coagulopathy in 1, renal failure in 2, and paraplegia in 3). At a median follow-up of 5.4 years (range, 1.7 to 7.9 years), no significant complications related to aortic repair occurred, except for three patients (10.3%) with asymptomatic dilatation of the visceral aortic patch<5 cm undergoing radiologic surveillance. CONCLUSION: Hybrid TAAA repair is technically feasible in selected cases. Perioperative morbidity and mortality were considerable in our subset of high-risk patients with prior aortic surgery, but no aneurysm-related or procedure-related complications were reported at mid-term follow-up. Hybrid TAAA repair did not lead to a significant improvement in outcomes compared with open TAAA repair in a similar group of patients. Larger series are required for valid statistical comparisons and longer follow-ups are necessary to evaluate the durability of hybrid repairs.     

Early experience with the minimal extracorporeal circulation system (MECC) during thoracoabdominal aortic aneurysm repair.

AIM: The purpose of this report is to describe our early experience with a minimal extracorporeal circulation system (MECC), a compact closed heparin coated system consisting of a centrifugal pump and a membrane oxygenator, during thoracoabdominal aortic aneurysm (TAAA) repair. METHODS: Between January and December 2002 the MECC system was employed in seven consecutive patients (four TAAA type II, two TAAA type I and one TAAA type III according to the Crawford classification). In all patients distal aortic, selective renal and visceral perfusion was performed with this compact closed heparin coated system consisting of a centrifugal pump and a membrane oxygenator. RESULTS: The MECC system was used in all cases with no technical malfunctions. Six out seven patients were discharged from the unit. One patient developed paraplegia after TAAA repair and died on the third post-operative day from multi-organ failure. In this case the total spinal ischaemic time was 120 min and the distal aortic perfusion pressure was <50 mmHg. No cardiac, cerebral, renal, hepatic or bleeding complications were recorded in the remaining six patients. CONCLUSION: Our early experience with MECC during TAAA repair showed that it is feasible for distal aortic spinal and visceral selective perfusion. Further large clinical trials are required to determine the efficacy of this technique.     

Comparative study of hypothermic circulatory arrest and normothermic distal perfusion for thoracoabdominal aortic aneurysm repair

BACKGROUND: Hypothermic bypass with circulatory arrest for thoracoabdominal aortic aneurysm (TAAA) repair is employed for its protective effect on spinal cord function and because it avoids clamping the diseased aorta. However, organ dysfunction caused by reperfusion injury as well as bleeding tendencies due to deep hypothermia have been described. In this paper we compared the efficacies of the hypothermic and normothermic operations. METHODS: Between February 1996 and June 2000, 28 patients underwent thoracoabdominal aortic repair. Twenty-three patients were men, 5 were women, and the median age was 55.3 (range 23 to 75 years). Fourteen patients had aortic dissection, and 7 had Marfan syndrome. Fourteen patients required reconstruction of visceral arteries. Twelve patients underwent TAAA repair under deep hypothermic circulatory arrest (H group), and 15 under normothermic distal perfusion (N group), while 1 patient underwent a simple clamp procedure. Perioperative data and early outcomes were compared between groups. RESULTS: The overall 30-day mortality rate was 0%, but 3 patients (25.0%) in II group, and 1 patient (6.3%) in N group died during hospital stay. Operation time and bypass time were longer in H group than N group (operative time 793 min vs. 481 min (p < 0.05): cardiopulmonary bypass (CPB) time 255 min vs. 102 min (p < 0.05). Also, more intraoperative bleeding was found in H group than in N group (3,506 ml vs. 1,220 ml). Spinal cord neurologic deficit did not occur in either group. Respiratory failure occurred in 3 patients (25.0%) in H group and one (6.3%) in N group. Renal failure occurred in 3 (25.0%) in H group, and none in N group. CONCLUSION: Early and mid-term outcome of TAAA repair was almost satisfactory and without neurospiral complications. The deep hypothermic operation is more likely to induce postoperative respiratory and renal dysfunction than the normothermic operation. TAAA repair using deep hypothermic circulatory arrest should be limited to patients with TAAA involving the distal arch or a severely calcified aortic wall.     

Deployment of balloon expandable stents during open repair of thoracoabdominal aortic aneurysms: a new strategy for managing renal and mesenteric artery lesions.

OBJECTIVE: Patients undergoing graft repair of thoracoabdominal aortic aneurysms (TAAAs) often require concomitant correction of ostial stenoses or dissection involving visceral branches. The purpose of this report is to describe our initial experience with a new strategy for addressing these lesions during open TAAA repair-direct deployment of balloon expandable stents into the renal and mesenteric arteries. METHODS: Over a two-year period, 367 patients have undergone TAAA surgery. Balloon expandable stents were used to manage visceral branch lesions during open TAAA repair in 93 (25.3%) of these patients. Fifteen patients (16%) had preoperative renal insufficiency. After opening the aneurysm and exposing the branch artery ostia, premounted balloon expandable stents were deployed in the affected vessels under direct vision. Stents were deployed after an endarterectomy in 40 patients (43%). Eighty patients (86%) had stents placed in one or both renal arteries and 36 (39%) had stents placed in the celiac axis and/or superior mesenteric artery. Postoperative renal function was monitored with daily serum creatinine levels. RESULTS: There were nine early operative deaths (10%). Two patients (2%) had bleeding complications related to stenting, one of which died after developing multiple organ failure. Twelve patients (13%) developed renal failure, eight of which required dialysis. CONCLUSIONS: This study demonstrates the feasibility of treating ostial lesions of the visceral branches with balloon expandable stents during open TAAA repair. Despite a high prevalence of preoperative renal insufficiency, the incidence of postoperative renal failure was acceptable. This new strategy may be a valuable adjunct to TAAA repair and warrants further investigation.     

Effect of suprarenal versus infrarenal aortic endograft fixation on renal function and renal artery patency: a comparative study with intermediate follow-up

PURPOSE: Suprarenal fixation of aortic endografts appears to be a safe option in patients with a short or conical proximal aortic neck. However, concern persists regarding the long-term effect on renal function when renal artery ostia are crossed by the uncovered stent. We investigated the effect of suprarenal versus infrarenal endograft fixation on renal function and renal artery patency after endovascular aortic aneurysm repair. METHODS: Records of 91 patients who underwent endovascular aortic aneurysm repair with a modular bifurcated stent graft between November 1999 and January 2002 were reviewed retrospectively. Two patients receiving dialysis because of chronic renal failure were excluded. Infrarenal fixation was used in 57 patients (group 1), and suprarenal fixation was used in 32 patients (group 2). In two patients in group 1 a Gianturco Z stent was inserted transrenally because of intraoperative proximal type I endoleak, and data for these patients were excluded from analysis. Follow-up evaluation was performed at 1, 6, and 12 months, and yearly thereafter, and included clinical assessment, measurement of serum creatinine concentration (SCr), and computed tomography angiography, per standard protocol. Median follow-up was 12 months (range, 1-36 months). RESULTS: There was no statistically significant difference in patient demographic data, aneurysm size, or preoperative risk factors. Median SCr was significantly higher in group 2 (suprarenal fixation) than in group 1 (infrarenal fixation) preoperatively (1.2 mg/dL [range, 0.6-2.3 mg/dL] vs 0.9 mg/dL [range, 0.6-1.9 mg/dL], P =.008) and at 1 month postoperatively (1.1 mg/dL [range, 0.8-5.6 mg/dL] vs 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.045). There was a significant increase in median SCr in both groups at 1 month postoperatively (group 1, 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.05; group 2, 1.1 mg/dL [range, 0.8-5.6 mg/dL] [mean SCr, 1.35 mg/dL vs 1.15 mg/dL, respectively], P <.05). In group 1 SCr was increased significantly at 6 and 12 months (P <.001), whereas in group 2 SCr also increased at 6 and 12 months, but not significantly. The change in SCr over time was not significantly different between the two groups. In two of 32 patients in group 2, renal artery occlusion developed, associated with perfusion defects in renal parenchyma and persistently elevated SCr. Analysis of renal artery patency did not demonstrate any association between patency and treatment. No patient developed hypertension during follow-up. CONCLUSIONS: Suprarenal endograft fixation does not lead to significant renal dysfunction, and renal artery occlusion is uncommon within 12 months. A larger study with longer follow-up is essential to determine overall effects on renal function and renal artery patency.     

Initial experience with the Nikkiso centrifugal pump during thoracoabdominal aortic aneurysm repair

Purpose: Several centers use atriodistal bypass (ADB) as a protective adjunct against distal ischemia during extensive thoracoabdominal aortic aneurysm (TAAA) repair. Most current ADB circuits use indirect-drive centrifugal pumps. The purpose of this report is to describe our initial clinical experience with the Nikkiso pump, a more compact direct-drive centrifugal pump recently developed at Baylor, for ADB during TAAA repair. Methods: The Nikkiso pump was used for ADB perfusion in 10 consecutive patients during graft repair of TAAAs (six Crawford extent I and four extent II). Two patients had aortic dissection. In the four patients who had extent II repairs, selective renal and visceral perfusion was also performed with the Nikkiso pump. Results: No mechanical pump malfunctions or adverse events related to the device occurred. All 10 patients survived and were discharged from the hospital. No patient had paraplegia after surgery. Two patients had delayed lower extremity weakness after undergoing extent I repairs; both recovered and were ambulating at the time of discharge. No complications were associated with bleeding or cerebral, respiratory, renal, or hepatic function. Conclusions: Our initial experience with the Nikkiso centrifugal pump during TAAA repair demonstrated excellent pump function that provided sufficient flow for both distal aortic and selective organ perfusion. The prevention of permanent spinal cord injury and distal organ failure was successful in this group. (J Vasc Surg 1998;27:378-83.)     

Visceral ischemia and organ dysfunction after thoracoabdominal aortic aneurysm repair. A clinical and cost analysis.

OBJECTIVE: Repair of thoracoabdominal aortic aneurysms (TAAAs) is associated with significant postoperative morbidity and mortality. Reperfusion of acutely ischemic abdominal viscera in animals leads to release of multiple factors that cause local and distant organ damage, and similar phenomena occurring in humans after TAAA repair could contribute to the high morbidity/mortality and cost associated with this procedure. METHODS: Twenty-nine patients undergoing elective TAAA repair were studied prospectively. Preoperative organ dysfunction and intraoperative risk factors (cross-clamp time, blood loss, operative time) were assessed and compared with postoperative organ dysfunction (defined as: pulmonary, positive pressure ventilation for > 7 days; renal, increase in serum creatinine > 2.0 mg/dL over baseline; hepatic, lactate dehydrogenase > 500 international units and total bilirubin > 3.0 mg/dL or serum transaminase level > 200 international units; hematopoietic, platelet count > 50 K or leukocyte count > 4.5 K, mortality, and costs. RESULTS: No relationship between preoperative organ dysfunction, blood loss, or operative time and postoperative organ dysfunction or mortality was seen; however, cross-clamp times > 40 minutes were associated with a significantly greater incidence of pulmonary (59%), renal (47%), hepatic (35%), and hematopoietic (47%) dysfunction. In addition, multiple-organ dysfunction (> 2 organ systems) was more common after > 40 minutes of visceral ischemia and led to significantly greater overall hospital ($88,465 + $76,155 vs. $41,782 + $31,244) and intensive care unit ($26,726 + $28,256 vs. $11,234 + $12,146) costs (p < 0.01, Mann-Whitney U test). Mortality associated with leukopenia was 67% compared with 4% without leukopenia (p < 0.01). CONCLUSION: Increasing durations of acute visceral ischemia led to significant multiple organ dysfunction after TAAA repair. Methods of limiting visceral ischemia or the systemic effects of visceral ischemia may decrease both the morbidity and mortality and the overall hospital cost associated with this procedure.     

Fate of the visceral aortic patch after thoracoabdominal aortic repair.

OBJECTIVE: To analyse the fate of a visceral aortic patch (VAP) in patients that underwent thoracoabdominal aortic aneurysm (TAAA) repair. METHODS: We reviewed 204 consecutive patients (158 M, 46 F) treated for TAAA between 1988 and 2004. We performed VAP in 182 cases. Among the 149 survivors at 6 months, we followed 138 cases, mean follow-up 7 years (range 0.6-16 years). The mean graft diameter we used was 29mm (range 24-34mm) from 1988 to 1999 (83 patients), and 21.7mm (range 16-24mm) from 2000 to 2003 (55 patients). In 23% of cases we performed a separate bypass to the left renal artery. RESULTS: We observed 16 (12%) VAP dilatations (<5cm), 6 (4%) VAP aneurysms (>5cm) and one VAP pseudoaneurysm, at a mean time of 6 years after atherosclerotic TAAA was atherosclerotic repair. There were no VAP dilatations/aneurysms in the group of patients with separate left renal revascularization. Five VAP aneurysms were treated electively. In four cases the operation was performed with thoracophrenolaparotomy, in one case with a bilateral subcostal laparotomy. In all cases the visceral aorta was re-grafted. Reimplantation of a single undersized VAP was performed in one case, separate revascularization of visceral arteries was performed in the other four cases. Selective intraoperative hypothermic perfusion of visceral and renal arteries was used in all the patients. There was 1 perioperative death; 2 patients with preoperative renal failure required dialysis. The last VAP aneurysm has remained asymptomatic and stable at annual CT surveillance. The VAP pseudoaneurysm was successfully treated with an emergency thoracophrenolaparotomy and refashioning the left side suture line. CONCLUSIONS: Aneurysm of VAP is not uncommon in the patients operated on using larger grafts with a single VAP that includes the LRA (7.4%, 5/67 cases). Its treatment carries significant morbidity and mortality.     

Estimated creatinine clearance instead of plasma creatinine level as prognostic test for postoperative renal function in patients undergoing coronary artery bypass surgery.

BACKGROUND: Preoperative renal failure is a risk factor for adverse events in cardiac surgery. Serum creatinine (SCr) is the most used test for renal failure. However, patients can have significantly decreased glomerular filtration rates with normal SCr levels. More accurate approximation of renal function can be obtained using the Cockroft-Gault equation to calculate an estimated creatinine clearance (CrCl) rate from SCr. METHODS: This study included 627 patients undergoing an isolated CABG between January 2003 and September 2004. CrCl was calculated using the Cockroft-Gault formula. Patients were divided in group A-SCr, 576 patients (91.1%) with a good renal function, SCr < or =1.20 mg/dL for women and < or =1.40 mg/dL for men, and a group B-SCr, with impaired renal function, 51 patients (8.1%). CrCl < or = 50 mL/min was chosen to reflect renal impairment. Group A-CrCl (555 patients, 88.5%) had a normal renal function and group B-CrCl (72 patients,11.5%) an impaired renal function. The studied outcomes were hospital mortality, hospital morbidity, and postoperative renal failure. RESULTS: There was no statistical significant difference between A-SCr and B-SCr group according to the studied outcomes. On the contrary, using the CrCl there was a statistical significant difference between A-CrCl and B-CrCl for the percentage of postoperative renal failure 10 patients (1.8%) versus 5 patients (6.9%) (p=0.00), hospital morbidity 75 patients (13.5%) versus 16 patients (22.2%) (p=0.04). Hospital mortality, 11 patients (2%) versus 4 patients (5.6%), was not significantly (p=0.06) different. Postoperative dialysis, four patients (0.7%) versus three patients (4.2%) (p=0.00), stroke, three patients (0.5%) versus three patients (4.2%) (p=0.00), and hospital stay (7.6 days vs 11.0 days) (p=0.01) were significantly different. CONCLUSION: This study documents that the association between preoperative renal failure and adverse outcomes after CABG is stronger with the estimated CrCl than with the routinely used SCr. Routine estimation or measurement of glomerular filtration rate should be preferred to SCr as screening method for the detection of higher risk patients undergoing CABG.     

Endovascular treatment of thoracoabdominal aortic aneurysms

OBJECTIVE: This study assessed the role of multibranched stent grafts for thoracoabdominal aortic aneurysm (TAAA) repair. METHODS: Self-expanding covered stents were used to connect the caudally directed cuffs of an aortic stent graft with the visceral branches of a TAAA in 22 patients (16 men, 6 women) with a mean age of 76 +/- 7 years. All patients were unfit for open repair, and nine had undergone prior aortic surgery. Customized aortic stent grafts were inserted through surgically exposed femoral (n = 16) or iliac (n = 6) arteries. Covered stents were inserted through surgically exposed brachial arteries. Spinal catheters were used for cerebrospinal fluid pressure drainage in 22 patients and for and spinal anesthesia in 11. RESULTS: All 22 stent grafts and all 81 branches were deployed successfully. Aortic coverage as a percentage of subclavian-to-bifurcation distance was 69% +/- 20%. Mean contrast volume was 203 mL, mean blood loss was 714 mL, and mean hospital stay was 10.9 days. Two patients (9.1%) died perioperatively: one from guidewire injury to a renal arterial branch and the other from a medication error. Serious or potentially serious complications occurred in 9 of 22 patients (41%). There was no paraplegia, renal failure, stroke, or myocardial infarction among the 20 surviving patients. Two patients (9.1%) underwent successful reintervention: one for localized intimal disruption and the other for aortic dissection, type I endoleak, and stenosis of the superior mesenteric artery. One patient has a type II endoleak. Follow-up is >1 month in 19 patients, >6 months in 12, and >12 months in 8. One branch (renal artery) occluded for a 98.75% branch patency rate at 1 month. The other 80 branches remain patent. There are no signs of stent graft migration, component separation, or fracture. CONCLUSIONS: Multibranched stent graft implantation eliminates aneurysm flow, preserves visceral perfusion, and avoids many of the physiologic stresses associated with other forms of repair. The results support an expanded role for this technique in the treatment of TAAA.     

Risk factors for development of acute renal failure after liver transplantation

BACKGROUND: Acute renal failure (ARF) is a common complication after liver transplantation (LTx). Identification of risk factors may prevent the development and attenuate the impact of ARF on patients outcome after LTX. METHODS: Retrospective analysis of variables in the pre, intra, and postoperative periods of 92 patients submitted to LTx was performed in order to identify risk factors for development of ARF after LTx. ARF was defined as serum creatinine > or = 2.0 mg/dL in the first 30 days after LTx. Univariate and multivariate analysis by logistic regression were performed. RESULTS: ARF group comprised 56 patients (61%). Preoperative serum creatinine was higher in ARF group. During the intraoperative period, ARF group required more blood transfusions, developed more episodes of hypotension and presented longer anesthesia time. In the postoperative period, ARF group presented higher serum bilirubin and more episodes of hypotension. Dialysis was required in 10 patients (11%). The identifled risk factors for development of ARF were: preoperative serum creatinine > 1.0 mg/dL. more than five blood transfusions in the intraoperative period, hypotension during intra and postoperative periods. The identified mortality risk factors were hypotension in the postoperative period and no recovery of renal function after 30 days. CONCLUSIONS: Several factors are involved in the pathogenesis of ARF after LTx and may influence patients outcome and mortality. Pretransplant renal function and hemodynamic conditions in the operative and postoperative periods were identified as risk factors for development of ARF after LTx. Nonrenal function recovery and postoperative hypotension were identified as mortality risk factors after LTx.     

Analysis of renal function after aneurysm repair with a device using suprarenal fixation (Zenith AAA Endovascular Graft) in contrast to open surgical repair

PURPOSE: This study was undertaken to assess the effect on renal function of open surgery and endovascular abdominal aortic aneurysm (AAA) repair with suprarenal fixation with the Zenith device. METHODS: Data for 279 patients with similar preoperative comorbid conditions were prospectively analyzed after AAA repair. One hundred ninety-nine patients underwent endografting with the Zenith AAA Endovascular Graft, which incorporates suprarenal fixation (Zenith standard risk group, ZSR), and 80 patients underwent open surgery (standard surgical risk group, SSR). Endovascular repair was also performed in 100 patients considered poor candidates for open repair (Zenith high risk group, ZHR). Serum creatinine concentration (SCr) and anatomic defects were assessed before the procedure, before discharge, and at 1, 6, 12, and 24 months in all patients who underwent endovascular repair, and before the procedure and at 1 and 12 months in patients who underwent open surgical repair (only SCr was measured before discharge). Renal function was also analyzed, with a creatinine clearance calculation (Cockcraft-Gault). Renal insufficiency was defined as an increase in SCr greater than 30% from a preoperative baseline value, any SCr concentration in excess of 2.0 mg/dL, or any need for dialysis. Cumulative renal infarction and arterial occlusion rates were calculated with computed tomographic, ultrasonographic, and angiographic data, and reported as cumulative values. RESULTS: Despite the initially superior renal function in the ZSR group at the pre-discharge evaluation (P =.01), there were no differences at 12 months with respect to rise in SCr greater than 30% (ZSR, 16%, vs SSR, 12%; P =.67), SCr rise greater than 2.0 mg/dL (ZSR, 2.5%, vs SSR, 3.4%; P =.66), incidence of renal artery occlusion (ZSR, 1%, vs SSR, 1.4%; P >.99), or infarction (ZSR, 1.5%, vs SSR, 1.4%; P >.99). Only one patient in each group required hemodialysis. Of note, both groups of patients demonstrated a reduction in creatinine clearance over 12 months, which then stabilized or improved by 24 months for ZSR patients. CONCLUSIONS: Renal dysfunction occurs in a subset of patients regardless of type of repair (open or endovascular with suprarenal fixation). The cause of renal dysfunction after open or endovascular repair with a suprarenal stent is probably multifactorial. The observed dysfunction occurs in a small number of patients, and the effect in the endovascular group (no data for the surgical group at 24 months) appears to be transient. The initial dysfunction, apparent in both groups over 12 months of follow-up, stabilizes or improves at 12 to 24 months.     

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.     

Collective experience with hybrid procedures for suprarenal and thoracoabdominal aneurysms

Not every patient is fit for open thoracoabdominal aortic aneurysm (TAAA) repair, nor is every TAAA or juxtarenal abdominal aortic aneurysm suitable for branched or fenestrated endovascular exclusion. The hybrid procedure consists of debranching of the renal and visceral arteries followed by endovascular exclusion of the aneurysm and might be an alternative in these patients. Between May 2004 and March 2006, 16 patients were treated with a hybrid procedure. The indications were recurrent suprarenal or thoracoabdominal aneurysms after previous abdominal and/or thoracic aortic surgery (n = 8), type I to III TAAAs (n = 3), proximal type I endoleak after endovascular repair (n = 2), penetrating ulcer of the juxtarenal aorta (n = 1), visceral patch aneurysm after type IV open repair (n = 1), and primary suprarenal aneurysm (n = 1). Eight (50%) of 16 patients were judged to be unfit for open TAAA repair. The hospital mortality rate was 31% (5 of 16). Four of five deceased patients were unfit for thoracophrenic laparotomy. Two patients died from cardiac complications and three from visceral ischemia. No spinal cord ischemia was detected, and temporary renal failure occurred in four patients (25%). The mean follow-up was 13 months (range 6-28 months). During follow-up, no additional grafts occluded and no patients died. Hybrid procedures are technically feasible but have substantial mortality (31%), especially in patients unfit for open repair (80%). They might be indicated when urgent TAAA surgery is required or when vascular anatomy is unfavorable for fenestrated endografts in patients with extensive previous open aortic surgery.     

Perioperative renal protection

AKI is the term to describe an abrupt reduction in kidney function and it replaces all previous terms such as ARF. The new definition for AKI needs to be validated by future research. Further development of biomarkers of AKI may aid in the early diagnosis and treatment of the syndrome. Mortality due to perioperative AKI often exceeds 50% and small changes in SCr correlate to significant increases in mortality. Preoperative risk factors for the development of AKI include a past history of renal dysfunction, elevated SCr, decreased cardiac performance, and cardiac and vascular surgery. Perioperative renal protection should focus on maintenance of euvolemia, preservation of adequate renal perfusion, and avoidance of any nephrotoxins. Intraoperative fluid management should be titrated to hemodynamic parameters and UO while avoiding excess fluid administration. The ideal fluid to administer is unknown as crystalloids and colloids each have their own advantages and disadvantages. Renal perfusion should be maintained by keeping MAP >65 mmHg and research may identify new techniques to monitor and individualize therapy to maintain renal perfusion. Recent data suggest that fenoldopam may alter outcome in patients with AKI.