Kimberley J. Hansen

Renal duplex sonography: Evaluation of clinical utility

With the exception of conventional angiography, no previously proposed screening test has the necessary sensitivity/specificity to guide further evaluation for correctable renovascular disease. Recently, renal duplex sonography has been suggested as a useful substitute in such screening for renovascular disease. This report analyzes our data collected over the past 10 months in evaluation of renal duplex sonography to examine its diagnostic value. The study population for renal duplex sonography validity analysis consisted of 74 consecutive patients who had 77 comparative renal duplex sonography and standard angiographic studies of the arterial anatomy to 148 kidneys. Renal duplex sonography results from six kidneys (4%) were considered inadequate for interpretation. This study population contained 26 patients (35%) with severe renal insufficiency (mean 3.6 mg/dl) and 67 hypertension (91%). Fourteen patients (19%) had 20 kidneys with multiple renal arteries. Bilateral disease was present in 22 of the 44 patients with significant renovascular disease. Renal duplex sonography correctly identified the presence of renovascular disease in 41 of 44 patients with angiographically proven lesions, and renovascular disease was not identified in any patient free of disease. When single renal arteries were present (122 kidneys), renal duplex sonography provided 93% sensitivity, 98% specificity, 98% positive predictive value, 94% negative predictive value, and an overall accuracy of 96%. These results were adversely affected when kidneys with multiple (polar) renal arteries were examined. Although the end diastolic ratio was inversely correlated with serum creatinine (r = -0.3073, p = 0.009), low end diastolic ratio in 35 patients submitted to renovascular reconstruction did not preclude beneficial blood pressure or renal function response. We conclude from this analysis that renal duplex sonography can be a valuable screening test in the search for correctable renovascular disease causing global renal ischemia and secondary renal insufficiency (ischemic nephropathy). Renal duplex sonography does not, however, exclude polar vessel renovascular disease causing hypertension alone nor does it predict hypertension or renal function response after correction of renovascular disease.

Contemporary surgical management of renovascular disease

To examine the treatment methods and early results of renovascular repair in our contemporary patient population, we reviewed our surgical experience during a recent 54-month period. From January 1987 to July 1991, 200 patients ranging in age from 5 to 80 years (mean, 56 years) were operated on for correction of nonatherosclerotic (43 patients) and atherosclerotic (157 patients) renovascular disease. The group included 92 men and 108 women, with blood pressures ranging from 300/198 mm Hg to 120/70 mm Hg (mean, 205/113 mm Hg). Defined by preoperative serum creatinine, 129 patients (65%) had evidence of renal insufficiency (Cr greater than or equal to 1.3 mg/dl), whereas 71 patients (36%) had severe renal insufficiency (Cr greater than 2.0 mg/dl; 11 patients were dependent on dialysis). One hundred forty-seven patients with atherosclerotic renovascular disease (94%) demonstrated organ-specific atherosclerotic damage. Operative management of 291 kidneys included unilateral renal artery repair in 117 patients (58%), bilateral repair in 78 patients (39%), and primary nephrectomy in five patients (2.5%). Simultaneous aortic reconstruction was required in 64 patients (32%). There were five operative deaths (2.5% mortality rate) and four occluded renovascular repairs (1.4% primary failure) within 30 days of surgery. Hypertension was considered cured in 21% and improved in 70% of 195 operative survivors. In 70 patients with severe renal insufficiency before operation, estimated glomerular filtration rate was improved in 49% (8 of 11 patients removed from dialysis), unchanged in 36%, and worsened in 15%. Renal function response was significantly influenced by the site of disease and the operation. Twenty-six additional postoperative deaths occurred during follow-up (range, 6 to 58 months; mean, 24.4 months). Extreme atherosclerotic-renovascular disease, preoperative renal insufficiency, failure to improve renal function, and progression to dependence on dialysis after operation were associated with follow-up deaths. Although most patients had a beneficial outcome, failure to improve extreme renal insufficiency was associated with a rapid rate of death during a relatively short follow-up period.

Surgical management of dialysis-dependent ischemic nephropathy

PURPOSE This retrospective review describes surgical management of dialysis-dependent ischemic nephropathy. METHODS From February 1987 through September 1993, 340 patients underwent operative renal artery (RA) reconstruction at our center. A subgroup of 20 patients (6 women; 14 men; mean age 66 years) dependent on hemodialysis immediately before RA repair form the basis of this report. Glomerular filtration rates (EGFR) were estimated from at least three serum creatinine measurements obtained 26 weeks before and after operation. A linear regression model was used to estimate the mean rate of change of EGFR before and after RA repair. Comparative analysis of kidney status and change in EGFR were performed. The influence of function response on follow-up survival was determined by the product-limit method. RESULTS Hemodialysis was discontinued in 16 of 20 patients (80%). For these 16 patients, postoperative EGFR ranged from 9.0 to 56.1 ml/min/1.73 m2 (mean 32.4 ml/min/1.73 m2). Two of 16 patients resumed hemodialysis 4 and 6 months after surgery. Discontinuation of dialysis was more likely after bilateral or complete RA repair (15 of 16 patients) versus unilateral repair (one of four patients; p = 0.01). Permanent discontinuation of dialysis was associated with a rapid preoperative rate of decline in EGFR (mean slope log(e) EGFR: -0.1393 +/- 0.0340 without dialysis; -0.0188 +/- 0.0464 with dialysis; p = 0.04, but NS after controlling for multiple comparisons). Immediate increase in EGFR after operation was inversely correlated with the severity of nephrosclerosis (rank correlation: -0.57; 95% confidence interval [-0.83, -0.10]). Follow-up death was associated with dialysis dependence; two deaths occurred among 14 patients not receiving dialysis, whereas five of six patients dependent on dialysis died (p < 0.01). CONCLUSION Surgical correction of ischemic nephropathy can retrieve renal function in selected patients dependent on dialysis characterized by a rapid decline in preoperative EGFR in combination with global renal ischemia treated by complete or bilateral renal revascularization. After RA repair, discontinuation of dialysis may be associated with improved survival rates when compared with continued dialysis dependence.

Results of endovascular aortic aneurysm repair with general, regional, and local/monitored anesthesia care in the American College of Surgeons National Surgical Quality Improvement Program database

BACKGROUND This study examined outcomes of endovascular repair of infrarenal abdominal aortic aneurysms (EVAR) using general, spinal, epidural, and local/monitored anesthesia care (MAC) in a multicenter North American hospital database reflecting contemporary anesthesia and surgical practices. METHODS Elective EVAR cases performed between 2005 and 2008 were identified from the American College of Surgeons National Surgical Quality Improvement Program database using Current Procedural Terminology codes. Excluded were emergency cases and patients with concomitant procedures requiring general anesthesia. Patient-level comorbidities, characteristics, and intraoperative and postoperative details were examined. Complications were analyzed individually and in aggregate categories, including wound, pulmonary, renal, venous thromboembolic, cardiovascular, operative, and septic. Length of stay (LOS) and 30-day mortality were examined. Characteristics and outcomes were described using mean ± standard deviation or count (%), and comparisons were evaluated for statistical significance using χ(2), Fisher exact test, and univariate linear regression. LOS was analyzed with linear regression techniques using a log transformation. Associations between anesthesia type and outcomes were examined using univariable and multivariable regression techniques. RESULTS We identified 6009 elective EVAR procedures for analysis. General anesthesia was used in 4868 cases, spinal anesthesia in 419, epidural anesthesia in 331, and local/MAC in 391. Defined morbidity occurred in 11% of patients. Median LOS was 2 (interquartile range, 1-3) days, and mean LOS was 2.8 ± 4.3 days. The 30-day mortality rate was 1.1%. Significant multivariate associations were observed between anesthesia type, pulmonary morbidity, and log-LOS. General anesthesia was associated with an increase in pulmonary morbidity vs spinal (odds ratio [OR], 4.0; 95% confidence interval [CI], 1.3-12.5; P = .020) and local/MAC anesthesia (OR, 2.6; 95% CI, 1.0-6.4; P = .041). Use of general anesthesia was associated with a 10% increase in LOS for general vs spinal anesthesia (95% CI, 4.8%-15.5%; P = .001) and a 20% increase for general vs local/MAC anesthesia (95% CI, 14.1%-26.2%; P < .001). Trends toward increased pulmonary morbidity and LOS were not observed for general vs epidural anesthesia. No significant association between anesthesia type and mortality was observed. CONCLUSIONS In contemporary North American anesthetic and surgical practice, general anesthesia for EVAR was associated with increased postoperative LOS and pulmonary morbidity compared with spinal and local/MAC anesthesia. These data suggest that increasing the use of less-invasive anesthetic techniques may limit postoperative complications and decrease the overall costs of EVAR.

Prevalence of ischemic nephropathy in the atherosclerotic population

Available data fail to define the prevalence of ischemic nephropathy or the association of critical renovascular disease (RVD) with renal function in the atherosclerotic population. The data do suggest, however, that critical RVD is prevalent and that the prevalence increases with age, increasing serum creatinine and clinical atherosclerosis at extrarenal sites. Furthermore, our preliminary data suggest that critical RVD may be either the cause or an important superimposed accelerant of renal insufficiency in a larger portion of the atherosclerotic population with renal insufficiency than previously recognized. In this latter group, critical RVD as a cause of renal insufficiency appears to be rapidly progressive and may contribute to end-stage renal disease with increasing frequency. Conclusive definition of the importance of ischemic nephropathy as a contributor to progressive renal insufficiency and end-stage renal disease will require population-based studies that estimate the prevalence of ischemic nephropathy and the natural history of the disease. Presently, renal duplex sonography appears to be the screening test of choice to define critical RVD for such population-based studies.

Duplex ultrasound scanning defines operative strategies for patients with limb-threatening ischemia

PURPOSE To characterize the accuracy of color-flow duplex ultrasound (DUS) in planning lower extremity revascularization procedures, we prospectively compared operations predicted by means of DUS arterial scanning (DUSAS) and operations predicted by means of conventional angiography (CA) with actual operations performed in 36 patients undergoing 40 vascular reconstructions for critical (grade II/III) lower extremity ischemia. METHODS All patients were examined with lower extremity DUSAS followed by CA. DUSAS was performed from the aorta to the pedal vessels of the affected extremity. Adequacy of inflow was assessed, and the best distal target vessel with continuous, unobstructed flow was defined. An operative prediction was made and recorded based upon the DUSAS findings, and in a blinded fashion, based upon subsequent CA. The McNemar test for comparing correlated proportions was applied to test for the statistical significance of the difference (P < .05) between correct operations predicted by DUSAS and CA. RESULTS Of the actual operations performed, 83% were correctly predicted by means of DUSAS (95% CI; range, 77% to 89%). Seven operations were incorrectly predicted with DUSAS. Of the actual operations performed, 90% were correctly predicted by means of CA (95% CI; range, 81% to 99%). Four operations were incorrectly predicted with CA. The McNemar test determined that the difference between correct operations predicted by means of DUSAS and correct operations predicted by means of CA was not statistically significant (P = .50). CONCLUSIONS With few exceptions, DUSAS can be used to reliably predict infrainguinal reconstruction strategies. Vessels defined as adequate with DUSAS are rarely unfit for bypass. Prospective investigation of lower extremity revascularization based solely upon DUSAS is warranted.

Clinical utility of the resistive index in atherosclerotic renovascular disease

OBJECTIVE This retrospective study examines the relationship between the renal resistive index (RI) and blood pressure and renal function response after open and percutaneous intervention for atherosclerotic renovascular disease (AS-RVD). METHODS From March 1997 to December 2005, 86 patients (46 women, 40 men; mean age, 68 +/- 10 years) underwent renal duplex sonography (RDS), including main renal artery and hilar vessel Doppler interrogation, before treatment of AS-RVD. Of these, 56 patients had open operative repair, and 30 had percutaneous intervention. The RI (1-[EDV/PSV]) was calculated from the kidney with the highest peak systolic velocity (PSV). Hypertension response was graded from preprocedural and postprocedural blood pressure measurements and medication requirements. Renal function response was graded by a >or=20% change in estimated glomerular filtration rate (eGFR) calculated from the serum creatinine concentration. RESULTS Comorbid conditions, baseline blood pressure, and preoperative renal function were not significantly different between open and percutaneous groups. Baseline characteristics that differed between the percutaneous vs open group were higher mean age (71 +/- 11 years vs 67 +/- 9 years; P = .05), kidney length (11.3 +/- 1.3 cm vs 10.7 +/- 1.2 cm; P = .02), proportion of patients with RI >or=0.8 (50% vs 21%; P = .01), and proportion of bilateral AS-RVD (37% vs 80%; P < .01). After controlling for preintervention blood pressure and extent of repair, postoperative eGFR differed significantly for RI <0.8 or >or=0.8 when all patients (P = .003) and percutaneous intervention (P = .008) were considered. Specifically, eGFR declined from preprocedure to postprocedure in the patients with RI >or=0.8 after percutaneous repair and in the group analyzed as a whole. Neither systolic nor diastolic pressure after intervention demonstrated an association with RI. Considering all patients and both groups, multivariable proportional hazards regression models demonstrated that RI was predictive of all-cause mortality. RI was the most powerful predictor of death during follow-up (hazard ratio, 6.7; 95% confidence interval, 2.6-17.2; P < .001). CONCLUSION After intervention for AS-RVD, RI was associated with renal function, but not blood pressure response. A strong, independent relationship between RI and mortality was observed for all patients and both treatment groups.

Chronic renal artery occlusion: nephrectomy versus revascularization.

PURPOSE The surgical management of chronic atherosclerotic renal artery occlusion (RA-OCC) was studied. METHODS From January 1987 through December 1996, 397 consecutive patients were treated for atherosclerotic renal artery disease. Ninety-five hypertensive patients (mean blood pressure, 204 +/- 31/106 +/- 20 mm Hg; mean medications, 3.0 +/- 1.1 drugs) were treated for 100 RA-OCCs. Eighty-four (88%) patients had renal dysfunction, defined by serum creatinine levels >/=1.3 mg/dL (mean serum creatinine level, 2.8 +/- 2.0 mg/dL). Demographic characteristics, operative morbidity and mortality, blood pressure/renal function response, and postoperative decline in renal function were examined and compared with that of 302 patients treated for renal artery stenosis (RAS). RESULTS After operation, there were 5 perioperative deaths (5.2%), 2 (2.8%) after revascularization and 3 (12%) after nephrectomy (P =.11), compared with 12 (4.0%) perioperative deaths in the RAS group (P =.59). After controlling for important covariates, estimated survival and blood pressure benefits did not differ between RA-OCC patients treated by nephrectomy or revascularization (P =.13; 87% vs 92%, P =.54). Excretory renal function was considered improved in 49% of 79 RA-OCC patients with renal dysfunction, including 9 patients removed from dialysis-dependence. Among patients treated for unilateral disease, revascularization for RA-OCC was associated with significant improvement in renal function (P <.01); however, nephrectomy alone did not increase renal function significantly. Improved renal function after operation was associated with a significant and independent increase in survival (P <.01) and dialysis-free survival (P <.01) among patients treated for RA-OCC. In addition, blood pressure benefit, renal function response, and estimated survival did not differ significantly after reconstruction for RA-OCC or RAS. CONCLUSION Among hypertensive patients treated for RA-OCC, equivalent beneficial blood pressure response was observed after both revascularization and nephrectomy. In patients who underwent bilateral renal artery revascularization, the change in excretory renal function attributable to repair of RA-OCC cannot be defined. In patients treated for unilateral disease, however, improvement in function was observed only after revascularization. Moreover, improved renal function demonstrated a significant and independent association with improved survival. This experience supports renal revascularization in preference to nephrectomy for RA-OCC in select hypertensive patients when a normal distal artery is demonstrated at operation.

Renal artery fibromuscular dysplasia: Results of current surgical therapy

PURPOSE This retrospective review describes current surgical management of renal artery (RA) fibromuscular dysplasia (FMD) to define contemporary clinical characteristics and surgical results in patients over the age of 21 years. METHODS From January 1987 through March 1994, 40 consecutive adults with hypertension had operative RA repair of FMD at our center and form the basis of this report. From histologic and angiographic appearance, FMD was classified with regard to specific type, noting the presence of RA dissections, RA macroaneurysms and branch RA involvement. Associations between blood pressure response to operation and patient age, duration of hypertension, presence of extrarenal atherosclerosis, presence of branch renal artery disease, and primary or secondary procedure were examined. Clinical characteristics and blood pressure response in these contemporary patients were compared with the results reported from an earlier surgical series. RESULTS Unilateral RA repair was performed in 34 patients, and bilateral procedures were required in six patients. Branch renal artery repair was performed in 28 instances, including ex vivo RA repair in 11 patients. There were no perioperative or follow-up deaths; however, three RA grafts (7%) failed within 30 days of operation. Initial blood pressure response was considered cured in 33%, improved in 57%, and failed in 10%. Analysis demonstrated that patients older than 45 years of age had a significantly decreased rate of hypertension cure compared with younger patients; among patients younger than 45 years of age, duration of hypertension was inversely related to cure. Compared with earlier surgical series, our current group of patients was significantly older, with more frequent branch renal artery involvement and extrarenal atherosclerosis, and demonstrated decreased rate of hypertension cure. CONCLUSION A beneficial blood pressure response is currently observed in most selected patients after surgical correction of RA-FMD. Compared with earlier series, however, the present day patient differs in many respects, including a significantly decreased chance for hypertension cure after surgical repair.

Intraoperative duplex sonography during renal artery reconstruction

To assess renal duplex sonography as an intraoperative study to detect technical defects during repair, 57 renal artery reconstructions in 35 patients were studied. Sixteen men and 19 women (mean age, 62 years) underwent unilateral (13 patients) or bilateral (22 patients) renal artery repair to 57 kidneys. Methods of repair included aortorenal bypass grafting in 29 cases (20 saphenous vein, 5 polytetrafluoroethylene, 4 Dacron), reimplantation in 7, transrenal thromboendarterectomy with patch angioplasty in 13, and transaortic extraction thromboendarterectomy in 8. Branch renal artery repair was required in six cases (five in vivo, one ex vivo). Fourteen patients had combined aortic replacement (11 patients: 8 abdominal aortic aneurysms, 3 aortic occlusions) or visceral artery reconstruction (three patients: three superior mesenteric artery thromboendarterectomies, one inferior mesenteric artery thromboendarterectomy). Intraoperative renal duplex sonography (mean scan time, 4.5 minutes) was complete in 56 of 57 repairs (98%), and renal duplex sonography was normal in 44 repairs (77%). Overall, B-scan defects were present in 13 repairs (23%). Six of these (11%) were defined as major B-scan defects by Doppler spectra with focal increases in peak systolic velocity greater than or equal to 2.0 meters/sec (major defect, mean renal artery peak systolic velocity, 3.1 m/sec), which prompted immediate operative revision. Seven B-scan defects were defined as minor by Doppler spectra (minor defect, mean renal artery, peak systolic velocity, 0.7 m/sec) and were not revised. Postoperative evaluation (range, 1 to 22 months; mean follow-up, 12.4 months) of 55 renal artery repairs in 34 operative survivors (surface renal duplex sonography, 33 patients; renal angiography, 9 patients) demonstrated 42/43 renal artery repairs with normal intraoperative renal duplex sonography, and 6/6 repairs with minor B-scan defects were patent and free of critical stenosis. Of the 6 renal artery revisions prompted by major B-scan defects, 4 remained patent, 1 stenosed, and 1 occluded. Our experience suggests that intraoperative renal duplex sonography during renal artery repair provides valuable anatomic and physiologic information. Renal artery repairs with normal renal duplex sonography and minor B-scan defects without Doppler spectral changes demonstrated 98% patency without critical stenosis at 12.4 months of mean follow-up. However, major B-scan defects defined by a focal increase in renal artery peak systolic velocity should be considered for immediate correction.