Open Repair of Aortic Aneurysms Involving the Renal Vessels
Article Outline
This retrospective review examines the open surgical repair of intact juxtarenal (JRAAs) and suprarenal (SRAAs) aortic aneurysms to estimate effects on survival and renal function. Patients undergoing open repair of JRAA and SRAA were identified. Preoperative medical comorbidities and perioperative and late outcomes were recorded. Primary end points were survival (perioperative and long-term survival) and changes in renal function (acute tubular necrosis [ATN], acute dialysis, and late functional decline). Associations between outcomes and clinical variables were examined using univariate and multivariate techniques. Between December 1996 and September 2006, 678 patients underwent open repair of aortic aneurysms, including 150 aneurysms involving the renal vessels (134 JRAAs, 16 SRAAs). Perioperative mortality was 3% and long-term survival was 69% at 5 years. Fourteen percent of patients experienced ATN, and 7% required acute in-hospital dialysis. Late renal function remained unchanged or improved in 75%. These results demonstrate a perioperative mortality and renal complication rate in keeping with previous reports of open abdominal aortic aneurysm repairs involving the renal vessels. Future implementation of branch and fenestrated aortic endografts to treat similar aneurysms should approximate these results prior to widespread acceptance.
Introduction
The introduction and widespread application of aortic endografts have dramatically changed the management of degenerative infrarenal aortic aneurysms. This new technology has been attributed with improvements in patient outcomes and reductions in aneurysm-related morbidity.1, 2 The success of these devices has resulted in a predictable overall decline in the number of open aortic reconstructions. This shift in care has also resulted in an increase in the proportion of open aortic aneurysm repairs with anatomy unsuitable for placement of conventional infrarenal aortic grafts.
Until recently, extension of the aneurysm to or above the renal artery orifices precluded endograft repair. However, recent advances in the design and construction of aortic endografts have resulted in devices that are now able to accommodate this more complex anatomy. Branched and fenestrated endografts have been developed to treat aneurysms of the visceral aorta and are being deployed in select centers. Given the success of infrarenal endografts, one might reasonably expect the application of these advanced designs to gain popularity and increased utilization in the near future. The application of these fenestrated and branched endografts will often require the deployment of stents, either bare metal or covered, to engage the renal and/or visceral vessels to facilitate complete aneurysm exclusion. The patency of these vessels, in particular the renal vessels, has been the subject of recent publications, raising concerns regarding their patency.3, 4, 5, 6
Few retrospective reviews have examined the results of open repair of juxtarenal (JRAAs) and suprarenal (SRAAs) aortic aneurysms.7, 8, 9, 10, 11 These studies have documented prolonged operative times and hospital stay as well as high rates of postoperative renal dysfunction. Mortality rates for JRAA and SRAA also appear to be higher than for open infrarenal aneurysm repair. However, few of these studies have focused on long-term survival or on renal function outcomes, in particular freedom from chronic kidney disease and renal failure.
With these factors in mind, we reviewed the perioperative outcomes of patients undergoing open repair of intact juxtarenal and suprarenal aortic aneurysms. The specific goals were to (1) examine the perioperative and follow-up survival and (2) estimate early and late renal function in patients undergoing open complex aneurysm repair involving the renal vessels.
Methods
Open aortic aneurysm repairs performed at Wake Forest University Baptist Medical Center between December 1996 and September 2006 were identified from a prospective institutional review board–approved vascular and endovascular surgery patient registry. Patients undergoing repair of aneurysms involving the juxtarenal (JRAA) or suprarenal (SRAA) aorta were included for analysis. Repairs of infrarenal, thoracoabdominal (including type IV), or ruptured aneurysms were excluded, as were reconstructions solely for aortic and branch aortic occlusive disease.
Patient Data
Information from the prospective patient registry combined with a retrospective review of patients' charts was used to compile a database consisting of preoperative medical risk factors, intraoperative variables, and postoperative outcomes. Preoperative medical risk factors and adverse patient outcomes were assessed based on Society for Vascular Surgery/International Society of Cardiovascular Surgery (SVS/ISCVS) guidelines for reporting standards.12 Operative variables recorded included American Society of Anesthesiologists (ASA) physical status classification, procedure indications and type, total operative time, anatomic location of aortic control along with total occlusion, and visceral and renal ischemia times. Additionally, the type of concomitant renal artery revascularization procedure and the results of intraoperative duplex sonography were recorded. Postoperative patient outcomes recorded included intensive care unit (ICU) and hospital stay, length of mechanical ventilation, requirement for a second operation during same hospital admission, as well as in-hospital morbidity and mortality. Morbidity included cardiac, pulmonary, neurologic gastrointestinal, visceral ischemic, peripheral ischemic, and wound complications occurring during the postoperative period as defined by the SVS/ISCVS guidelines.12 Major morbidity was defined as any event which resulted in reoperation, required medical or procedural intervention such as a transfer to a higher level of patient care, or prolonged patient hospital stay.
Renal Outcomes
Renal events were assessed as early complications and late functional changes. Early renal complications included acute tubular necrosis (ATN) and acute dialysis. ATN was defined as both a ≥20% increase in preoperative serum creatinine (SCr) during the first 7 postoperative days and a level >1.5 mg/dL in a male and 1.3 mg/dL in a female. Patients with elevations in SCr beyond 7 days were not deemed as having ATN related to surgery. Acute dialysis was defined as the need for new dialysis (either temporary or permanent) during the same hospital admission. Late renal function was assessed using the abbreviated Modification of Diet in Renal Disease (MDRD) equation to estimate glomerular filtration rate (EGFR): [EGFR/1.73 m2 = 186∗(SCr)−1.154∗(Age)−0.203∗(0.742 if female)∗(1.210 if African American)]. A significant decline in renal function was delineated as a ≥10% annualized decline in EGFR from preoperative admission to the most recent follow-up measure. Patency of renal artery repair was assessed by renal duplex sonography using previously described techniques and defined as patent, stenotic, or occluded.13
Mortality Outcomes
Early mortality was defined as a perioperative death within 30 days of surgery or during the same admission regardless of the length of hospital stay. Long-term survival was assessed through the National Death Index (NDI) report, which contains information from state vital statistics offices on date and cause of death and was current through 2004 at the time of manuscript preparation. The NDI information was supplemented with information from direct clinic and telephone contact for more recent aneurysm repairs.
Anatomic Definitions
For the purposes of this study, a JRAA was defined as any distal aortic aneurysm which, during the course of repair, required proximal clamp placement above at least one renal artery (see Fig. 1). The aneurysmal portion could involve one renal artery or abut the inferior edge of one or both renal arteries. An SRAA was defined as any aortic aneurysm which involved the aortic segment above the renal arteries, thus requiring a revascularization of one or both renal arteries and proximal clamp placement above the renal and possibly the visceral vessels (see Fig. 1). Finally, a renal artery reconstruction was defined as any renal artery reimplantation, endarterectomy, or bypass performed during an aneurysm repair.
Fig. 1
Juxtarenal and suprarenal aortic aneurysms.
Statistical Analysis
The primary end points for analysis were survival and renal events (both early and late). Secondary end points included perioperative morbidity and major morbidity. For the purpose of analysis, patients undergoing JRAA and SRAA repair were considered separately and compared in terms of demographics, preoperative medical risk factors, perioperative variables, and postoperative outcomes using the chi-squared or Fisher exact test for dichotomous variables and the Student t- or Kruskal-Wallis test for continuous variables. These methods were also used to evaluate univariate associations between demographic and medical covariates and the primary end points (perioperative mortality and renal events). Associations between covariates and late mortality were assessed using univariate Cox proportional hazards regression models. Patient survival was assessed using Kaplan-Meier product-limit estimates. Independent associations were assessed using stepwise variable selection procedures to develop multivariate regression models using logistic regression for perioperative mortality and early and late renal outcomes, while Cox's proportional hazards regression was used for late mortality (p = 0.10 for model entry). Variables with more than 15 missing values (10% of the sample) were excluded from the stepwise selection process. All analyses were conducted using SAS Statistical Software (version 9.1; SAS Institute, Cary, NC). p < 0.05 was considered statistically significant.
Results
Between December 1996 and September 2006, 678 patients underwent open repair of aortic aneurysms at our institution. From this group we identified 16 SRAA repairs and 134 JRAA repairs. Included in these 150 aneurysm patients were 50 patients who underwent renal reconstruction in conjunction with aneurysm repair. Excluded were infrarenal aortic aneurysms (including those who underwent renal artery reconstruction), ruptured aneurysms, and thoracoabdominal aneurysm repairs.
Patient demographics and clinical variables are listed in Table I. The mean age of the entire group was 71 years. Both groups were predominantly white (97%) and male (72%). Mean aneurysm size was 5.9 cm, and mean preoperative creatinine for the group was 1.3 mg/dL. Three patients had end-stage renal disease preoperatively, one with long-standing and two with recent-onset dialysis who underwent renal artery reconstruction in an attempt at renal function salvage. There were no statistical differences between the JRAA and SRAA groups with regard to age, gender, ethnicity, aneurysm size, and preoperative creatinine.
Table I. Demographics and clinical variables
| JRAA (n = 134) | SRAA (n = 16) | All aneurysms (n = 150) | pa | |
|---|---|---|---|---|
| Ageb | 71.0 ± 8.0 | 69.1 ± 8.2 | 70.8 ± 8.0 | NS |
| Male | 99 (74%) | 9 (56%) | 108 (72%) | NS |
| Race | ||||
 White | 129 (96%) | 16 (100%) | 145 (97%) | NS |
| African American or other | 5 (4%) | 0 (0%) | 5 (3%) | |
| Weight (kg)b | 81.3 ± 18.0 | 84.2 ± 21.8 | 81.6 ± 18.3 | NS |
| Height (cm)b | 175.6 ± 9.4 | 172.5 ± 14.3 | 175.3 ± 10.0 | NS |
| Obesity (BMI ≥25 kg/m2) | 61 (64%) | 8 (73%) | 69 (65%) | NS |
| Aneurysm size (cm)b | 5.9 ± 1.2 | 5.6 ± 1.5 | 5.9 ± 1.3 | NS |
| Preoperative creatinine (mg/dL)bc | 1.2 ± 0.6 | 1.4 ± 0.6 | 1.3 ± 0.6 | NS |
| Preoperative dialysis | 2 (1%) | 1 (6%) | 3 (2%) | NS |
| Cardiac ejection fractionb | 54.0 ± 11.2 | 58.2 ± 13.2 | 54.5 ± 11.5 | NS |
| Inducible ischemia on stress ECHO | 5 (6%) | 1 (10%) | 6 (6%) | NS |
| Coronary diseased | 86 (64%) | 10 (63%) | 96 (64%) | NS |
| Pulmonary diseased | 44 (33%) | 5 (31%) | 49 (33%) | NS |
| Renal insufficiencyd | 36 (27%) | 5 (31%) | 41 (28%) | NS |
| Stroke/TIAd | 24 (18%) | 5 (31%) | 29 (19%) | NS |
| Diabetesd | 22 (17%) | 2 (13%) | 24 (16%) | NS |
| Hyperlipidemiad | 73 (55%) | 9 (56%) | 82 (55%) | NS |
| Hypertensionc | 121 (91%) | 13 (81%) | 134 (90%) | NS |
| Smoking historyd | 107 (80%) | 13 (81%) | 120 (81%) | NS |
| Peripheral vascular diseased | 23 (17%) | 2 (13%) | 25 (17%) | NS |
aComparison between JRAA and SRAA. |
bMean value ± standard deviation. |
cExcludes patients on renal replacement therapy. |
dBased on SVS/ISCVS reporting guidelines. |
Operative variables examined are listed in Table II. Median operative time was 300 min, and median visceral and/or renal ischemia time was 30 min. Patients in the JRAA group experienced significantly shorter operative times (JRAA 288 vs. SRAA 410 min, p = 0.001) and renal or visceral ischemia times (JRAA 30 vs. SRAA 42 min, p = 0.036). Consistent with anatomic considerations, patients in the JRAA group required significantly fewer renal artery reconstructions than those in the SRAA group (35 [26%] vs. 15 [94%], respectively; p < 0.001). Of note, one patient in the SRAA group had long-standing preoperative dialysis dependence and did not undergo renal artery reconstruction during aneurysm repair.
Table II. Operative variables
| JRAA (n = 134) | SRAA (n = 16) | All aneurysms (n = 150) | pa | |
|---|---|---|---|---|
| Timing | ||||
| Elective | 119 (89%) | 15(94%) | 134(89%) | NS |
| Urgent | 15 (11%) | 1(6%) | 16(11%) | |
| Operative time (min)b | 288 (113) | 410(176) | 300(120) | 0.001 |
| Clamp level | ||||
| Juxtarenal | 57 (43%) | - | 57(38%) | <0.001 |
| Suprarenal | 52 (39%) | 7(44%) | 59(39%) | |
| Supra-superior mesenteric artery | 18 (13%) | 7(44%) | 25(17%) | |
| Supraceliac | 7 (5%) | 2(13%) | 9(6%) | |
| Total aortic occlusion time (min)b | 69 (36) | 82(42) | 70(36) | 0.069 |
| Renal and visceral ischemia time (min)b | 30 (16) | 42(21) | 30(18) | 0.036 |
| Procedure type | ||||
| Tube | 80 (60%) | 10(63%) | 90(60%) | |
| Aortoiliac | 50 (37%) | 6 (38%) | 56 (37%) | NS |
| Aortofemoral | 4 (3%) | - | 4 (3%) | |
| Renal reconstruction | ||||
| None | 99 (74%) | 1 (6%) | 100 (67%) | <0.001 |
| Reimplantation | 3 (2%) | 3 (19%) | 6 (4%) | |
| Endarterectomy | 12 (9%) | 2 (13%) | 14 (9%) | |
| Bypass grafting | 20 (15%) | 10 (63%) | 30 (20%) | |
| Intraoperative duplexc | 16 (46%) | 11 (73%) | 27 (54%) | 0.073 |
| Intraoperative revision | 1 (3%) | 2 (13%) | 3 (6%) | NS |
| ASA classification | ||||
| II | 5 (4%) | - | 5 (3%) | |
| III | 90 (68%) | 12 (80%) | 102 (69%) | NS |
| IV | 37 (28%) | 3 (20%) | 40 (27%) |
aComparison between JRAA and SRAA. |
bMedian (interquartile range) p values from the Kruskal-Wallis test. |
cReflects only patients who underwent renal artery reconstruction. |
Patient operative outcomes are listed in Table III. There were five perioperative deaths, for a mortality rate of 3%, which was not different between the JRAA and SRAA groups (3% vs. 6%, respectively; p = nonsignificant [NS]). Two of the five perioperative mortalities were attributed to multiple organ system failure secondary to pulmonary sepsis. Two patients suffered severe perioperative cardiac dysfunction related to fatal myocardial infarctions including one who required intraoperative cardiopulmonary resuscitation. Three of the five mortalities developed renal failure requiring acute dialysis, while one of the perioperative mortalities was preoperative dialysis-dependent. Four of the five perioperative mortalities occurred during the same hospital admission, while one patient with marked cardiac systolic dysfunction had an uncomplicated postoperative hospital course but suffered ventricular fibrillation and expired shortly after discharge. Follow-up was complete for 145 of the 150 patients (97%). The overall product-limit survival estimates are depicted in Figure 2. With a median follow-up of 32 months, the 5-year survival was 69% for all patients and not significantly different in the JRAA and SRAA groups (70% vs. 65%, respectively; p = NS).
Table III. Patient operative outcomes
| JRAA (n = 134) | SRAA (n = 16) | All aneurysms (n = 150) | pa | |
|---|---|---|---|---|
| Mortality | ||||
| Perioperative | 4 (3%) | 1 (6%) | 5 (3%) | NS |
| Any during follow-up | 33 (25%) | 4 (25%) | 37 (25%) | NS |
| Acute tubular necrosis | 16 (12%) | 5 (33%) | 21 (14%) | 0.042 |
| Acute postoperative dialysis (transient or permanent) | 6 (5%) | 4 (27%) | 10 (7%) | 0.011 |
| Declined late renal function (median follow-up 17.9 months)b | 22 (24%) | 4 (36%) | 26 (25%) | NS |
| Postdischarge-onset dialysis | 5 (4%) | 2 (13%) | 7 (5%) | NS |
| Any morbidityc | 48 (36%) | 10 (63%) | 58 (39%) | 0.038 |
| Major morbidityc | 31 (23%) | 6 (38%) | 37 (25%) | NS |
| Length of hospital stay (days)d | 8 (5) | 10 (7) | 8 (6) | 0.080 |
| Length of ICU stay (days)d | 3 (3) | 5 (5) | 3 (3) | 0.032 |
| Mechanical ventilation (days)d | 1 (2) | 1 (6) | 1 (2) | 0.072 |
| Subsequent procedure (complication-related) | 13 (10%) | 3 (19%) | 16 (11%) | NS |
| Cardiac complicatione | 20 (15%) | 4 (25%) | 24 (16%) | NS |
| Pulmonary complicatione | 24 (18%) | 4 (25%) | 28 (19%) | NS |
| Neurologic complicatione | 2 (1%) | 1 (6%) | 3 (2%) | NS |
| Gastrointestinal complicatione | 7 (5%) | 3 (19%) | 10 (7%) | 0.075 |
| Visceral ischemic complicatione | 3 (2%) | 2 (13%) | 5 (3%) | 0.088 |
| Peripheral ischemic complicatione | 2 (1%) | 1 (6%) | 3 (2%) | NS |
| Wound complicatione | 15 (11%) | 2 (13%) | 17 (11%) | NS |
aComparison between JRAA and SRAA (for complications, p values reflect any vs. none). |
bAssessed based on ≥10% annualized decline in EGFR from preoperative measure; percentage reflects only those patients with follow-up EGFR measurement. |
cExcludes renal morbidity. |
dMedian (interquartile range) p values from the Kruskal-Wallis test. |
eBased on SVS/ISCVS reporting guidelines. |
Fig. 2
Kaplan-Meier product-limit estimates for overall survival after juxtarenal or suprarenal aortic aneurysm repair.
Perioperative morbidity occurred in 39% of patients, and a major morbidity occurred in 25% of patients. The rate of any morbidity was significantly greater in the SRAA group (JRAA 36% vs. SRAA 63%, p = 0.038), though not for major morbid events (JRAA 23% vs. SRAA 38%, p = NS). Median length of ICU stay was 3 days and was significantly longer in the SRAA group (JRAA 3 days vs. SRAA 5 days, p = 0.032).
ATN occurred in 21 patients (14%), and 10 patients (7%) required acute dialysis. Of the 10 patients who needed acute dialysis, eight had ATN and the remaining two had hospital courses complicated by sepsis. In the SRAA group there was a significantly higher incidence of ATN (JRAA 12% vs. SRAA 33%, p = 0.042) and rate of acute dialysis (JRAA 5% vs. SRAA 27%, p = 0.011). The mean discharge creatinine for the whole group was 1.3 mg/dL (median interval 8 days), and follow-up creatinine was 1.4 mg/dL (median interval 17.9 months); these were not significantly different between the JRAA and SRAA groups. Twenty-six of the 104 patients (25%) with follow-up SCr (median follow-up 17.9 months) demonstrated significant declines in EGFR, while the remaining 75% were unchanged or improved in follow-up, with no differences between the JRAA and SRAA groups (76% vs. 64%, respectively; p = NS). Seven patients developed renal failure after discharge, requiring initiation of dialysis; the rate was not significantly different between the two groups (JRAA 4% vs. SRAA 13%, p = NS). Thirty of the 50 patients (60%) who underwent renal artery reconstruction had follow-up renal duplex examinations (JRAA 54% vs. SRAA 73%, p = NS). All repairs were patent on follow-up renal duplex sonographic exam, including two of the seven patients who developed renal failure after discharge.
The significant univariate associations for survival are listed in Table IV and associations for the renal end points in Table V. Of particular note, the length of ICU stay and the need for prolonged mechanical ventilation both demonstrated significant associations with perioperative and long-term survival as well as ATN, acute dialysis, and long-term renal function decline. Similarly, the presence of a postoperative pulmonary complication was associated with these same survival and renal end points.
Table IV. Univariate associations: survival outcomes
| Perioperative mortality | Late mortalitya | |||
|---|---|---|---|---|
| Variable | ORb | pc | HRa | pa |
| Age (years) | 1.05 | 0.046 | ||
| Preoperative renal insufficiencyd | 2.10 | 0.051 | ||
| Preoperative dialysis dependence | 17.88 | 0.097e | 3.81 | 0.072 |
| Continuous systolic ejection fraction (%) | 0.97 | 0.038 | ||
| Urgent operation | 2.85 | 0.016 | ||
| Renal and visceral ischemia time (min) | 1.01 | 0.009 | ||
| Length of hospital stay (7-day change) | 1.30 | <0.001 | ||
| Length of ICU stay (3-day change) | 1.09 | 0.013f | 1.13 | <0.001 |
| Length of mechanical ventilation (days) | 1.06 | 0.001f | 1.05 | <0.001 |
| Subsequent procedure | 5.90 | <0.001 | ||
| Cardiac complicationd | 25.00 | 0.002e | ||
| Pulmonary complicationd | 20.17 | 0.004e | 6.78 | <0.001 |
| Peripheral vascular complicationd | 17.88 | 0.097e | 5.34 | 0.024 |
| Visceral ischemia complicationd | 11.09 | 0.002 | ||
| Wound complicationd | 4.09 | 0.002 | ||
| Any renal complication | 17.43 | 0.014e | ||
| Acute dialysis | 58.29 | <0.001e | ||
| Postdischarge-onset dialysis dependence | 7.56 | <0.001 | ||
aCox's proportional hazards regression models. |
bORs from simple logistic regression for continuous variables or contingency tables for categorical variables. |
cChi-squared test of association unless otherwise stated. |
dBased on SVS/ISCVS reporting guidelines. |
eFisher's exact test. |
fKruskal-Wallis test. |
Table V. Univariate associations: renal outcomes
| Acute tubular necrosis | Acute dialysis | Late functional decline | ||||
|---|---|---|---|---|---|---|
| Variable | ORa | pb | ORa | pb | ORa | pb |
| Age | 1.07 | 0.056f | ||||
| Male gender | 4.26 | 0.043 | ||||
| ASA classification IVc | 5.23 | <0.001 | 4.98 | 0.019g | ||
| Hyperlipidemiad | 0.45 | 0.097 | 0.08 | 0.005g | ||
| Preoperative renal insufficiencyd | 3.12 | 0.016 | ||||
| SRAA repair | 3.63 | 0.042g | 7.64 | 0.011g | ||
| Urgent operation | 4.09 | 0.079g | ||||
| Operative time (30 min change) | 1.26 | 0.003h | 1.23 | 0.001h | ||
| Total aortic clamp time (min) | 1.02 | 0.011h | 1.02 | 0.050h | ||
| Renal and visceral ischemia time (min) | 1.01 | 0.001h | 1.01 | 0.032h | 1.00 | 0.085h |
| Aortic clamp location | ||||||
| Suprarenal vs. juxtarenal | 0.65 | 0.002g | 1.02 | 0.002g | ||
| Supra-superior mesenteric artery vs. juxtarenal | 2.68 | 2.39 | ||||
| Supraceliac vs. juxtarenal | 10.63 | 22.00 | ||||
| Length of hospital stay (7-day change) | 1.22 | <0.001h | 1.33 | <0.001h | 1.13 | 0.043h |
| Length of ICU stay (3-day change) | 1.11 | <0.001h | 1.21 | <0.001h | 1.11 | 0.001h |
| Length of mechanical ventilation (days) | 1.06 | <0.001h | 1.11 | <0.001h | 1.03 | 0.017h |
| Subsequent procedure | 4.64 | 0.013 | 11.45 | 0.002g | ||
| Cardiac complicationd | 6.61 | 0.009g | ||||
| Pulmonary complicationd | 6.25 | <0.001g | 14.49 | <0.001g | 7.50 | <0.001g |
| Peripheral vascular complicationde | 0.020g | 0.004g | ||||
| Visceral ischemia complicationd | 16.88 | 0.023g | ||||
| Wound complicationd | 2.97 | 0.071g | ||||
| Acute tubular necrosis | 3.41 | 0.032g | ||||
| Acute dialysis | 4.55 | 0.064g | ||||
aORs from simple logistic regression for continuous variables or contingency tables for categorical variables. |
bChi-squared test of association unless otherwise stated. |
cAmerican Society of Anesthesiologists physical status classification. |
dBased on SVS/ISCVS reporting guidelines. |
eOR not available due to one or more empty cells. |
fIndependent-samples t-test. |
gFisher's exact test. |
hKruskal-Wallis test. |
Independent predictors for the survival and renal events were examined using multivariate stepwise selection techniques. Meaningful independent associations for perioperative mortality could not be assessed due to the limited number of deaths. For late follow-up mortality, the following parameters were independently predictive: history of diabetes (hazard ratio [HR] = 3.63, 95% confidence interval [CI] 1.18-11.20; p = 0.025), length of hospital stay (standardized to 7 days) (HR = 1.34, 95% CI 1.15-1.56; p < 0.001), postoperative pulmonary complication (HR = 4.61, 95% CI 1.49-14.27; p = 0.008), ATN (odds ratio [HR] = 0.19, 95% CI 0.04-0.83; p = 0.027), and renal failure after discharge (HR = 28.64, 95% CI 3.15-260.64; p = 0.003). For the early renal complication ATN, we identified age (OR = 1.11, 95% CI 1.01-1.21; p = 0.031), postoperative pulmonary complication (OR = 5.66, 95% CI 1.77-18.08; p = 0.004), and operative time (standardized to 30 min) (OR = 1.37, 95% CI 1.15-1.64; p < 0.001). For acute dialysis, the only independent association identified was the number of ventilator days (OR = 1.11, 95% CI 1.06-1.17; p < 0.001). Finally, the parameters independently associated with late renal function decline were operative time (standardized to 30 min) (OR = 1.19, 95% CI 1.00-1.41; p = 0.048) and postoperative pulmonary complication (OR = 5.19, 95% CI 1.45-18.61; p = 0.012).
Discussion
The widespread application of infrarenal aortic endografts has had a predictable effect on aortic aneurysms submitted to open surgery. Today, it is perceived that a larger portion of open aneurysm repairs involve complex aortic and renal anatomy not readily amenable to treatment by devices currently approved by the U.S. Food and Drug Administration and being deployed in most centers. In particular, this increased anatomic complexity often involves aneurysmal degeneration of the juxtarenal and suprarenal aorta. This report examines a group of 150 patients who underwent open repair of intact JRAAs and SRAAs during a recent 10-year period. This group experienced a perioperative mortality of 3% and long-term survival of 69% at 5 years. ATN occurred in 14%, and acute dialysis was required in 7% during the postoperative period. Moreover, 75% of the group maintained unchanged or improved renal function at 18 months of follow-up. These results are in keeping with previously published reports on open aneurysm repairs of the juxtarenal and suprarenal aorta and document a similar long-term survival to that reported following open and endovascular infrarenal aneurysm repair.14, 15
Other retrospective studies have examined open repair of intact aneurysms involving the juxtarenal aorta. Jean-Claude et al.11 reviewed their group's experience with pararenal and juxtarenal aortic aneurysms and identified an overall mortality of 5.8% in 257 patients treated over a 20-year period. By multivariate techniques, they noted that visceral ischemic complications as well as intraoperative and postoperative bleeding complications were independently related to perioperative mortality. Sarac et al.16 reviewed their group's results with JRAA in 138 patients. With an observed mortality rate of 5.1%, they identified the use of a supravisceral aortic clamp for proximal aortic control as being associated with a sixfold increased risk of perioperative mortality. West et al.9 reviewed their groups' experience with JRAA and identified 2.8% in-hospital perioperative mortality in 247 patients. They noted that preoperative renal insufficiency (SCr >1.5 mg/dL), supravisceral clamp location, mesenteric ischemia time, and the amount of required blood transfusion were all independently predictive of perioperative mortality. Finally, Back et al.8 reviewed their group's results of 158 JRAAs, SRAAs, and thoracoabdominal aortic aneurysms and reported a 5.4% perioperative mortality. They identified visceral ischemia time as being independently associated with a nearly 11-fold increased risk of mortality, particularly visceral ischemia times greater than 32 min. Back et al. also examined long-term survival and noted a 73% 5-year survival by life-table analysis. These and other additional reports document perioperative in-hospital mortalities ranging 1.3-7.5%. Our perioperative mortality rate of 3% is in keeping with these published reports and is similar to our previously documented 5.3% mortality in combined aortic and renal surgery.17 Additionally, our observed 69% 5-year survival is similar to previous reports of open and endovascular aortic aneurysm repair.8, 14, 15
Considering these studies collectively, perioperative mortality for JRAA and SRAA appears to be associated with the length of visceral ischemia and/or the requirement for a supravisceral aortic clamp. Bleeding complications also appear to be a major independent predictor of perioperative mortality. Though blood loss and transfusion requirement were not examined in this study, no independent associations with visceral ischemia time or clamp location were identified in this report. System-related complications, including cardiac, pulmonary, and renal complications, all demonstrated univariate associations with perioperative mortality as well as length of ICU stay and mechanical ventilation. Moreover, acute postoperative dialysis was associated with a significant univariate risk of perioperative mortality (OR = 58.29, 95% CI 5.36-634.36; p < 0.001) as one-third of the patients (3 of 10) who required acute dialysis expired in the perioperative period. The lack of an observed association between visceral ischemia and mortality in our study may, in part, be a result of the retrospective nature of this study and the resulting incompleteness in this particular end point (n = 101 available). Another potential explanation for the lack of association may be that the limited number of perioperative deaths afforded insufficient statistical power to demonstrate an association. Despite the obvious potential bias, model selection was repeated for only those patients with recorded total aortic clamp time or total visceral and/or renal ischemia times, and this approach still failed to identify an independent association.
Renal complications are an unfortunate reality for aneurysm repairs of the juxtarenal and suprarenal aorta as well as renal reconstruction. Qvarfordt et al.7 and Jean-Claude et al.11 from UCSF have reported renal complication rates ranging 23-40% and an acute dialysis rate of 0-7%, while Sarac et al.16 documented a renal complication rate of 27.5%. Similarly, West et al.9 reported a renal complication rate of 22% and an acute dialysis rate of 4%. We identified a renal complication (ATN) rate of 14% in our group of aneurysm repairs and an acute dialysis rate of 7%, including two patients who developed acute renal failure secondary to postoperative pulmonary sepsis. The JRAA group experienced a lower rate of ATN (12% vs. 33%, p = 0.042) and rate of acute dialysis (5% vs. 27%, p = 0.011) than the SRAA group. These findings are likely attributable to the anatomic requirements for suprarenal aneurysm repair, which necessitated a longer period of visceral and renal ischemia (30 vs. 42 min, p = 0.036). Furthermore, a significantly greater portion of patients in the SRAA group had concomitant hemodynamic renal artery stenosis which required correction during aneurysm repair (JRAA 18% vs. SRAA 50%, p = 0.007).
Independent predictors of postoperative renal complications have also been examined.8, 9, 10 Many authors have identified preoperative renal insufficiency as well as supravisceral aortic clamp placement and length of visceral ischemia to be independent predictors of acute renal complication. The addition of a renal revascularization procedure also appears to increase the risk of renal complications. Similar multivariate associations were not observed in our patient group for ATN or acute dialysis using the above-described techniques. However, when total aortic occlusion time (n = 18 missing) was included in the multivariate models, both preoperative renal insufficiency (OR = 4.36, 95% CI 1.20-15.82; p = 0.025) and total aortic occlusion time (OR = 1.03, 95% CI 1.01-1.05; p = 0.002) were predictive of postoperative ATN. The same did not hold true when renal or visceral ischemia time (n = 49 missing) was substituted for total occlusion time. Finally, neither of these alternate multivariate models identified additional predictors for acute dialysis. Fortunately, these and other studies document modest rates of acute renal dysfunction, which often resolves without the need for renal replacement therapy.
The long-term durability of renal revascularization in patients undergoing aortic aneurysm repair is largely unknown. We have previously documented an overall renal artery repair failure rate of 3.9% at a mean follow-up of 56 months.17 It is routine practice to perform renal duplex on all patients who undergo renal artery repair at our institution. Though limited by completeness, 30 of 50 (60%) renal artery reconstructions had adequate follow-up duplex examinations which identified no renal artery thromboses and only two unilateral stenoses.
Long-term survival and freedom from aneurysm- and renally related morbidity are the goals of surgical repair of aortic aneurysms involving the renal vessels. It is conceivable that patients with aneurysms involving the juxtarenal or suprarenal aorta might have larger burden of atherosclerotic vascular disease, thus contributing to an increased perioperative mortality and reduction in long-term survival. To this end, it does appear that patients who undergo JRAA and SRAA repair experience a slightly higher perioperative mortality rate than those submitted to open infrarenal repair and when compared to historic controls at our institution.19 However, the long-term survival of patients with JRAA and SRAA does not appear to be adversely affected. Reports of open or endovascular repair of infrarenal aneurysms as well as patients who have undergone renal artery repair for renovascular disease document similar 5-year survival rates, with some reports demonstrating rates less than our observed 69%.14, 15, 17
Little is known about the long-term effects of a transient period of warm renal ischemia on renal function. Twenty minutes of warm ischemia is associated with recovery of renal function in minutes to hours, while 30 min of ischemia may require 3-9 days for recovery and the long-term effects of this ischemic insult are unknown.19 Our results suggest that if the transient ischemia is well tolerated in the perioperative period (i.e., minimal rise in SCr), then the long-term effects appear limited. However, if marked renal tubular dysfunction results, as seen with ATN or the need for acute dialysis, the effects on renal function appear to be longer-lasting as 40% (7 of 17 perioperative survivors with follow-up EGFR) demonstrated persistent significant declines in renal function on recent measures.
New aortic endograft designs able to accommodate aortic aneurysms involving the renal and visceral vessels are now being deployed in a limited number of centers. As these devices are still in development and early application phases, their results and long-term durability are still unproven. Initial reports have documented perioperative 30-day mortalities ranging 0.4-2.7%.3 However, unique to these devices is the use of fenestrations and/or prefabricated branches and bare metal or covered stents to engage the renal and visceral orifices and provide aneurysm exclusion. The utilization of these newer techniques has raised questions about the long-term patency of these target visceral vessels. A recent meta-analysis reviewing the literature on fenestrated endografts noted renal or visceral branch perfusion rates of 97% and 90% in the perioperative and follow-up periods, respectively, as well as a periprocedural rate of renal dysfunction of 22%.3 A recent report from the Cleveland Clinic noted 10 renal artery stenoses and five occlusions in 142 renal arteries.4 Moreover, 17 of 72 patients (24%) had significant declines in EGFR (defined as >30% decline from baseline) during early follow-up; only four patients went on to dialysis dependence.
Renal function and freedom from dialysis dependence have significant influence on long-term patient survival. The association between chronic kidney disease and increased mortality has been recognized by many. Population-based studies have recently demonstrated that chronic kidney disease results in a significantly increased risk of cardiovascular events (including myocardial infarction and stroke) as well as all-cause mortality.20, 21 This increased risk may be proportionally similar to that of other well-recognized cardiovascular risks and has been observed with only moderate reductions in renal function (EGFR <60 mL/[min·1.73 m2]).22 These associations are also supported by our experience with ischemic nephropathy. While only 10% of patients in our experience demonstrated a decline in renal function during the perioperative period after renal artery repair, this decline was associated with a significant increased risk of death or dialysis during follow-up.17 Assessment of further strategies for management of aneurysms of all types should consider renal function results after treatment as an important surrogate measure of long-term success.
A number of limitations of this study require comment. First, this is a retrospective review of a single institution's experience, and the findings are based on selected variables extracted from the medical record. This retrospective design lends itself to a number of potential biases, including patient selection, preoperative assessment, and perioperative management, which have evolved during the study period. Additionally, the incomplete collection of variables such as visceral ischemia time and the limited number of morbid and renal events limited our power to identify meaningful independent associations with the end points of interest. Despite these limitations, the results of renal function and survival analyses are not likely to be adversely affected as they were extracted from a nonsubjective laboratory analysis in the case of renal function and confirmed by the results of the NDI search in the case of late survival.
Conclusion
The results of this study demonstrate perioperative morbidity and renal complication rates in keeping with previous reports of similar patients. The observed 69% 5-year survival and 75% unchanged or improved renal function suggests that patients who undergo aortic aneurysm repair of the juxtarenal or suprarenal aorta as well as aneurysm repair with renal artery reconstruction are not at a disproportionately increased risk of late mortality or renal function decline. These results along with those of other published reports on aneurysm repair involving the renal vessels show that future branched and fenestrated endografts should be compared.18
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Presented at the Peripheral Vascular Surgery Society Winter Meeting, Steamboat Springs, CO, January 26-28, 2007.
PII: S0890-5096(07)00282-8
doi:10.1016/j.avsg.2007.07.011
© 2007 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
