|Home | About | Journals | Submit | Contact Us | Français|
We aimed to identify factors related to technical and clinical success of percutaneous revascularization for blunt renal arterial trauma.
All cases of percutaneous revascularization for blunt renal arterial trauma were searched in the available literature. We included a case of iatrogenic renal artery occlusion at our institution treated by percutaneous stenting 20 hours after injury. A pooled cohort analysis of percutaneous revascularization for blunt renal artery injury was then performed to analyze factors related to technical and clinical success. Clinical failure was defined as development of new hypertension, serum creatinine rise, or significant asymmetry in split renal function.
A total of 53 cases have been reported, and 54 cases were analyzed including our case. Median follow-up was 6 months. Technical success was 88.9% and clinical success was 75%. Of 12 treatment failures (25%), 66.7% occurred during the first postprocedure month. Time from injury to revascularization was not a predictor of clinical success (OR=1.00, P = 0.681). Renal artery occlusion was significantly associated with clinical failure (OR=7.50, P = 0.017) and postintervention antiplatelet therapy was significantly associated with treatment success (OR=0.16, P = 0.043). At 37-month follow-up, the stented renal artery in our case remained patent and the patient was normotensive with preserved glomerular filtration rate.
Percutaneous revascularization for blunt renal arterial injury resulted in relatively high technical and clinical success. Time-to-revascularization was independent of successful outcomes. Clinical success was significantly associated with a patent renal artery at the time of intervention and with postprocedure antiplatelet therapy.
Acute traumatic kidney injury may result in sequelae spanning a spectrum from complete recovery to renal insufficiency and kidney failure (1). Despite the broad differential of inciting factors, the mechanism of injury is felt to be related to loss of organ perfusion with irreversible ischemic changes occurring within the first 24 hours. As such, urgent intervention is essential to prevent renal compromise. While conservative therapy may be sufficient in mild cases, more severe traumatic arterial injury may require intervention. Depending on the nature of the injury, treatment options include open surgical intervention and endovascular intervention. Although surgery is the standard of care for bilateral renal artery injury, it is generally less effective in cases of unilateral injury (1). In light of these findings, percutaneous endovascular stenting has become a potential alternative treatment (2, 3). Although results vary greatly, ranging from complete renal recovery to nephrectomy, reported outcomes may be improved over open surgical techniques and warrant further exploration.
The high degree of variability in outcomes in these patients remains a limiting factor in establishing accurate treatment guidelines (4). In this report, we present a pooled data analysis of all patients in the available literature with blunt renal vascular injury who have been treated with percutaneous techniques. We include a case of successful unilateral renal artery revascularization with percutaneous endovascular stenting at our institution despite prolonged ischemia time in a young patient.
We explored PubMed and CINAHL databases using the keywords (“renal artery” AND [“injury” OR “trauma”] AND [percutaneous OR stent OR angioplasty OR transluminal]). Thirty-six relevant publications with at least one case of blunt renal artery trauma treated by stenting, angioplasty, or both were identified. Of these, 31 were case reports and five were studies with a retrospective analysis of data. Data for individual cases were extracted from these manuscripts for further analysis. Clinical failure was defined as development of new hypertension, serum creatinine rise or significant asymmetry in split renal function (i.e., less than 25% of the total activity in the affected kidney) (5) on the last reported follow-up visit. All available case reports were included based on the Joanna Briggs Institute (JBI) critical appraisal checklist for case reports and case series, as appropriate (6).
We included our case in all analyses, for a total of 54 cases. Numerical variables were reported as median (minimum-maximum) and categorical variables were reported as frequency (percentage). Risk factors of renal loss after percutaneous intervention were evaluated by univariate binary logistic regression models with post-stenting clinical failure (defined above) as the dependent outcome variable. We included age, gender, hematuria, and renal artery occlusion on presentation, time to intervention, and postprocedure heparin or antiplatelet use as independent exposure variables. Odds ratios (ORs) were calculated as the ratio of odds of developing post-stenting clinical failure in a given independent exposure variable relative to its reference category (e.g., male versus female for gender). The statistical software STATA IC for Windows version 14.1 was used to analyze the data, and P values less than 0.05 were considered significant. Institutional Review Board approval was waived for the single case review from our institution.
A total of 53 cases were described in 36 publications (2, 3, 7–40). The publications are summarized in Table 1. A case from our institution was included in analysis, for a total of 54 cases. The first case was reported in 1995 (7). Table 2 demonstrates a summary of the reported subjects’ characteristics. In the total study population, median age was 21 years, with 62% being males (male-to-female ratio ≈ 2:1). The right renal artery was the injured artery in most of the cases (right-to-left ratio ≈ 2:1), and subjects had a median of two other associated injuries. Median time of follow-up was 6 months (range, 0–48.7 months) after intervention. Two cases reported injury of a solitary kidney. Case reports presented almost 50% fewer failures than retrospective data analyses (OR=0.48, P = 0.327).
Renal artery injury was initially diagnosed by contrast-enhanced abdominal CT scan in 37 patients (68.5%). Median reported time to revascularization was 8 hours (range, 1.83 hours to 25 days). Forty-nine cases (90.7%) were treated by primary stent placement, two cases were treated by balloon angioplasty without stenting, and one case was treated by thrombolysis. Two patients underwent metallic coil and Amplatzer plug embolization after failed recanalization. Of the deployed stents, 30 (61.2%) were balloon-expandable, 7 (14.3%) were self-expandable, and 12 (24.5%) were of unknown type. Stent grafts were deployed in 7 cases. Postintervention warfarin was administered in 2 subjects. Twenty cases were given heparin for 48 hours postintervention and antiplatelet therapy was administered in 19 cases (35.2%). Follow-up diagnostic imaging included renal scintigraphy (46.2%), duplex ultrasonography (40.4%) and contrast-enhanced CT (38.5%).
After excluding subjects with technical failure (n=6, Table 3), kidney function loss occurred in 12 of 48 cases (25%) during the follow-up period, 8 (66.7%) of which occurred during the first month. Clinical failure cases are described in Table 4. Stent restenosis or occlusion was reported in four cases (7.4%), two of whom underwent re-stenting. Three patients developed hypertension, two of whom also had a documented rise in serum creatinine level at 4 weeks follow-up. Seven subjects had less than 25% split renal function in the affected kidney on follow-up scintigraphy. Three patients in the total pool ultimately underwent nephrectomy, one of whom had documented < 25% activity on split renal function. Two patients died at follow-up, neither from renal causes. One case of renal artery dissection that could not be stented went on to develop symptomatic hypertension with headaches, rise in serum creatinine, and minimal function in the affected kidney on split renal function testing. This patient then underwent a second procedure with successful stenting of the dissected renal artery 25 days after the injury. Hypertension promptly resolved after stenting; however, there was a persistent rise in serum creatinine level with only minimal increase in split renal function at 4-week follow-up.
Univariate logistic regression analysis was performed to identify predictors of renal function loss after intervention (Table 5). Occlusion of the affected renal artery at the time of intervention was associated with clinical failure (OR=8.46, P = 0.012). Postprocedure antiplatelet therapy (aspirin, clopidogrel, or both) was associated with clinical success (OR=0.16, P = 0.043). The time interval between renal artery injury and revascularization was independent of clinical success (OR=1.00, P = 0.681).
The following case from our institution was also included in the analysis: a 25-year-old male with extragonadal germ cell tumor and residual postchemotherapy lymphadenopathy who underwent combined resection of an anterior mediastinal mass and extensive retroperitoneal lymph node dissection. Palpable renal arterial pulses were noted after the lymph node dissection prior to closing the abdomen. Through that evening, the patient developed increasing creatinine to 1.77, up from his preprocedure baseline of 0.86 (baseline estimated glomerular filtration rate [eGFR], 121 mL/min/1.73m2). Renal duplex ultrasound performed the following day demonstrated absent blood flow to the left kidney (Fig. 1a). The patient was subsequently taken to the interventional radiology suite, approximately 20–24 hours after his surgery, for attempted renal artery revascularization. An abdominal aortogram at that time demonstrated occlusion of the left renal artery just beyond the origin (Fig. 1b). The occlusion was successfully crossed, demonstrating severe intimal injury to the proximal left renal artery with associated thrombus. Primary stenting of the proximal left renal artery was performed using an 8 mm × 29 mm balloon-expandable bare metal stent (Palmaz Genesis, Cordis), successfully re-establishing flow to the left kidney (Fig. 1c). Of note, no significant excretion of contrast from the left kidney was noted during the procedure, indicative of acute renal injury. Postprocedure, the patient had normal vital signs and good left renal arterial flow by duplex ultrasound imaging (Fig. 1d). He was discharged home on oral clopidogrel (75 mg daily) and aspirin (81 mg daily).
Follow-up duplex ultrasound imaging at 3 months demonstrated a patent left renal artery stent with mild interval loss of left renal parenchymal volume. Resistive indices of the left kidney were normal at 0.5, similar to the right kidney. A CT scan performed during this time also demonstrated mild interval atrophy of the left kidney to approximately 75% of its baseline size compared with the CT scan prior to his lymph node dissection (Fig. 2a). Atrophy was primarily seen in the anterior cortex with intact perfusion to the posterior kidney. The left renal artery stent was patent, and the nephrograms comparing the viable portions of the left kidney with the right kidney were symmetric. Additional follow-up renal duplex ultrasound examinations over the following year again confirmed patency of the left renal artery stent with good waveforms and peak systolic velocities. He was taking prazosin and valproic acid for psychiatric management, but was otherwise not on any antihypertensive medication. At 20 months postprocedure, duplex US examination demonstrated a patent left renal artery with brisk upstroke and normal parenchymal resistive indices (Fig. 2b). A MAG-3 renal scintigraphy study demonstrated a 2:1 split renal function, with 67% on the right and 33% on the left (Fig. 2c). At 24 months from renal artery stenting, duplex renal US demonstrated stent patency, normal resistive indices, patent renal veins, and stable left renal size at 9.4 cm (Fig. 2d). Furthermore, his blood pressure was 113/60 mmHg, and his renal function was preserved with a serum creatinine of 0.96 mg/dL, giving a normal eGFR of >60 mL/min/1.73m2. At the time of his most recent follow-up, approximately 37 months after intervention, duplex US demonstrated a patent left renal artery stent with normal parenchymal resistive indices and preserved eGFR.
Renal artery injury from blunt trauma is relatively rare, occurring in approximately 0.08% of cases (14). Prolonged ischemia after renal artery occlusion secondary to blunt trauma may result in sequelae including hypertension, impairment of renal function, and kidney failure (3, 7). As such, an important aspect in guiding therapy is the identification of maximal ischemic time beyond which irreversible injury occurs. Data regarding renal ischemic tolerance from the surgical literature in patients undergoing partial nephrectomy suggest a limited window for revascularization before irreversible kidney injury is sustained. One study evaluating 362 patients with a solitary kidney who underwent partial nephrectomy with follow-up obtained at 3 and 12 months identified a renal artery cross clamp time of 25 minutes beyond which there was a four-fold greater risk of developing new onset renal compromise. This same study also reported increased odds of developing renal failure of approximately 5% for every minute beyond the 25-minute threshold (41). While the above findings support the notion that time to intervention remains an essential consideration in treatment, the suggested duration may not apply to all patients. Published case reports and case series for traumatic renal arterial injury have used longer times to reperfusion as guidelines, generally on the order of 4–12 hours, and some up to 24 hours (3, 7). The illustrative case from our institution demonstrates successful renal artery revascularization after a prolonged ischemia time of approximately 20–24 hours with preservation of renal function at over 37 months follow-up. Serial US examinations demonstrated persistent patency of the renal stent and mild atrophy of the affected kidney, with approximately 20% loss of renal function estimated based on the split renal function. Overall renal function was preserved, with a normal eGFR. The partial atrophy noted on CT imaging was segmental in location, localized primarily to the anterior region with good perfusion to the posterior cortex. It is unclear whether this may have been a result of the original injury or a result of distal emboli after stenting, as has been recently shown (34). This case features a relatively accurate time to reperfusion based on the operative report, compared with the variability in timing in many blunt trauma settings.
Our pooled cohort analysis demonstrated no association between time-to-revascularization and outcome success at 6 months follow-up. In support of this, a retrospective analysis from 6 university trauma centers found that elapsed time to operative renal revascularization after major renovascular trauma was not correlated with renal outcome (5). While an occluded renal artery at the time of intervention was significantly associated with treatment failure in our analysis, our case demonstrated successful recanalization and renal preservation despite occlusion of the renal artery. Antiplatelet therapy after renal artery stenting was significantly associated with treatment success. In a previous study of renal artery stenting for hypertension, no difference was seen in acute or late occlusion between patients treated with anticoagulation and aspirin compared with aspirin alone at 6 months follow-up (42), supporting the role of antiplatelet therapy in stent patency.
Limitations of this study include the retrospective nature of the analysis and possible publication bias as described above. As such, the true denominator of patients with blunt renal arterial trauma who are managed with endovascular procedures remains unknown. Also, univariate regression analysis with a limited number of published cases might not be a strong strategy for the given conclusions. However, currently this is the strongest method given sparsity of the publications on blunt trauma of renal artery.
In conclusion, we present a pooled cohort analysis of endovascular treatment of blunt renal arterial injury in the available literature. Our findings suggest prolonged ischemia time should not necessarily dissuade attempted percutaneous revascularization, and that postprocedural antiplatelet therapy is likely important for treatment success. We report a case of renal artery injury managed with percutaneous stenting after prolonged ischemia of over 20 hours, with preserved renal function after 3 years of follow-up. These findings may help design future guidelines in the management of blunt renal artery injury.
Conflict of interest disclosure
The authors declared no conflicts of interest.