Sheila M. Coogan

Blunt traumatic aortic injury: initial experience with endovascular repair.

OBJECTIVES Endovascular treatment of traumatic aortic injury (TAI) is an alternative to open repair (OR) in patients with blunt trauma. We report our initial experience after integration of endovascular repair using thoracic devices. METHODS A retrospective review of a prospectively collected institutional trauma registry was performed. Between September 2005 and November 2008, 71 patients with TAI presented to our institution. Based on imaging, TAIs were classified into grade 1-4 in severity. These included: grade 1, intimal tear; grade 2, intramural hematoma; grade 3, aortic pseudoaneurysm; and grade 4, free rupture. Initial management included resuscitation, blood pressure control, and treatment of associated injuries. After stabilization, all patients were considered for thoracic endovascular aortic repair (TEVAR) using a thoracic device. If contraindicated, candidates underwent OR. Outcome measures were mortality, stroke, paraplegia, intensive care unit (ICU), and hospital stay. RESULTS The mean age was 39.8 years, with 50 males. The mean injury severity score (ISS) was 42.6. Nineteen (27%) patients with a mean ISS of 60 died shortly after arrival prior to any vascular intervention. Ten (14%) patients with grade 1 injuries were managed medically. The remaining 42 (59%) patients with grade 2 and 3 injuries underwent repair. Median interval between admission and repair was 4.3 days (range, 0-109 days). Fifteen (21%) patients with a mean ISS of 34.4 underwent OR with no mortality, stroke, or paraplegia. Twenty-seven (38%) patients with a mean ISS of 36.7 underwent TEVAR with no mortality or paraplegia. One TEVAR patient suffered a perioperative stroke. Twenty-two patients had a TAG (W.L. Gore & Associates, Flagstaff, Ariz) device. Four patients had a Talent Thoracic (Medtronic Vascular, Santa Rosa, Calif), and 1 patient had an Excluder (W.L. Gore) device. The left subclavian artery was covered in 13 (48%) patients. Patients who underwent TEVAR were older than those who had OR (47.8 vs 31.1 years, P < .006). The aortic diameter proximal to the injury was larger in the TEVAR group (24.4 vs 19.6 mm, P < .0001). There was no difference in the mean ICU or hospital length of stay between the two groups. Mortality correlated with the ISS score (P < .0001). Median follow-up time was 19.4 months (range, 0-27). Only 56% of the TEVAR patients were fully compliant with their surveillance imaging protocol. CONCLUSION In this initial experience, the results of TEVAR did not differ from OR. Long-term follow-up is required to determine the effectiveness of this treatment strategy. Adherence to follow-up imaging protocols is challenging in this patient population. Next generation devices will make TEVAR applicable to a wider range of patients.

Progress in the Treatment of Blunt Thoracic Aortic Injury: 12-Year Single-Institution Experience

BACKGROUND Recent advancements in the diagnosis and management of blunt thoracic aortic injury have improved outcomes after operative repair. With consideration of these advancements, we analyzed our level 1 trauma experience with blunt traumatic aortic injury. METHODS Between January 1997 and March 2009, 255 patients with blunt traumatic aortic injury were entered into the Utah Trauma Registry-Trauma Center Registry. Of these, 145 (58%) patients underwent thoracic aortic repair, with 12 (5%) undergoing aortic exploration without repair. Median age was 32 years (range, 13 to 87), with 43 (30%) women. Repair approach included open repair without adjunct (clamp), open with distal aortic perfusion, open with cardiopulmonary bypass, and thoracic endovascular aortic repair. The affect of management modifications, which included use of distal aortic perfusion (1999), delayed repair (2002), and use of thoracic endovascular aortic repair (2005) was analyzed. We used multiple logistic regression to evaluate the changes in morbidity (paraplegia and stroke) and mortality attributable to changes in surgical practice, adjusted for calendar time and injury severity score. RESULTS Mortality from operative aortic intervention for blunt thoracic aortic injury (BTAI) was 17% (24 of 145). Delayed repair, used in 41% (59 of 145) of repairs, was associated with only 1 death (2%), which was significantly lower than immediate repair 28% (23 of 86) mortality (p < 0.002). Mean injury severity score was 39 +/- 11. Adjusted for injury severity score and calendar time, delayed repair resulted in a greater than tenfold reduction in mortality compared with immediate open intervention (odds ratio 0.07, p < 0.02). Use of thoracic endovascular aortic repair was associated with zero mortality (p < 0.03 versus other treatments). Mortality with open repair with and without distal aortic perfusion was 14% and 31%, respectively, p < 0.02. Paraplegia occurred in 10% with open repair without distal aortic perfusion, and in no cases in open with distal aortic perfusion and thoracic endovascular aortic repair. CONCLUSIONS Although thoracic aortic injury still accounts for significant mortality during blunt trauma, patients reaching specialized trauma centers can achieve good results with thoracic aortic repair. Improved early outcomes have been observed with delayed selective management and thoracic endovascular repair. Long-term results of thoracic endovascular aortic repair, however, need further study.

An outcome analysis of endovascular versus open repair of blunt traumatic aortic injuries

BACKGROUND Aortic injury is the second most common cause of death after blunt trauma. Thoracic endovascular aortic repair (TEVAR) has been rapidly adopted as an alternative to the traditional open repair (OR) for treatment of traumatic aortic injury (TAI). This paradigm shift has improved the outcomes in these patients. This study evaluated the outcomes of TEVAR compared with OR for patients with TAI. METHODS We analyzed prospectively collected data from the institutional trauma registry between April 2002 and June 2010. These data were supplemented with a retrospective review of hospital financial accounts. The primary outcome was the presence or absence of any complication, including in-hospital death. Secondary outcomes included fixed, variable, and total hospital costs and intensive care unit (ICU), preoperative, postoperative and total hospital length of stay (LOS). RESULTS Amongst 106 consecutive patients (74 men; mean age, 36.4 years), 56 underwent OR and 50 underwent TEVAR for treatment of TAI. The proportion of patients who underwent TEVAR compared with OR increased from 0% to 100% during the study period. The TEVAR patients were significantly older than the OR patients (41.1 vs 32.2 years, P=.012). For patients who underwent TEVAR, the estimated odds ratio (95% confidence interval) of complications, including in-hospital mortality was 0.33 (0.11-0.97; P=.045) compared with the OR group. The average number of complications, including in-hospital death, was higher in the OR group than in the TEVAR group (adjusted means, 1.29 vs 0.94). The OR group had a higher proportion of patients with complications, including in-hospital death, compared with the TEVAR group (69.6% vs 48%). Although, the mean adjusted variable costs were higher for TEVAR than for OR (P=.017), the mean adjusted fixed and total costs were not significantly different. Owing to a policy of delayed selective management, the adjusted preoperative LOS was significantly higher for TEVAR (9.8 vs 3.0 days, P=.022). The difference in the ICU or total hospital LOS was not significant. Although the proportion of uninsured patients was similar in both groups, the cohort (n=106) had a significantly higher proportion of uninsured patients (29% vs 5%) compared with the general vascular surgical population at our institution (0.29 vs 0.051, 95% confidence interval for difference in proportions, 0.22-0.40; P<.0001). CONCLUSIONS Compared with TEVAR, patients who underwent OR had three times higher odds to face a complication or in-hospital death. The mean total cost of TEVAR was not significantly different than OR. The findings support the use of TEVAR over OR for patients with TAI.

Intraoperative skeletal muscle ischemia contributes to risk of renal dysfunction following thoracoabdominal aortic repair

OBJECTIVE Renal dysfunction is among the most commonly occurring morbidities following descending thoracic and thoracoabdominal aortic repair. We hypothesized that myoglobin nephrotoxicity might arise from leg ischemia caused by femoral artery cannulation, which is required for distal aortic perfusion. Lacking complete historical laboratory data on myoglobinemia, we studied somatosensory evoked potential (SSEP) changes in the leg (a functional marker of leg ischemia), as a surrogate predictor of acute postoperative renal failure. METHODS Intraoperative leg SSEP function and preoperative glomerular filtration rate (GFR - an essential covariate) were available for 299 patients. Change in SSEP was defined as 10% increase in latency or 50% decrease in amplitude. Postoperative renal dysfunction was 1mg/dl/day increase in creatinine for 2 days, clinical diagnosis of ARF or need for dialysis postoperatively. RESULTS Change in SSEP in the cannulated leg occurred in 108/299 (36%) of cases intraoperatively. All recovered normal SSEP function at decannulation. Patients with SSEP changes had 41/108 (38%) postoperative renal failure compared to 49/191 (26%) without (odds ratio 1.8, p<0.03). Modeled with GFR, aneurysm extent, and chronic obstructive pulmonary disease (COPD), SSEP changes had an adjusted odds ratio of 1.9, p<0.03. Pre-op GFR was also a highly significant predictor of postoperative renal failure (OR 0.98/ml; p<0.0001). CONCLUSION This is the first study to show a relationship between intraoperative leg ischemia and postoperative renal failure. It provides epidemiological evidence that the ischemic leg may be an important contributor to rhabdomyolysis-like renal morbidity after thoracoabdominal aortic surgery.

Outcomes of endovascular repair for patients with blunt traumatic aortic injury.

BACKGROUND Traumatic aortic injury (TAI) remains a leading cause of death after blunt force. Thoracic endovascular aortic repair (TEVAR) has been widely adopted as an alternative to open repair for the treatment of TAI. Although significant short-term benefits have been demonstrated for patients undergoing TEVAR, longer-term follow-up data are lacking. METHODS Trauma registry data were analyzed. Follow-up data were gathered from a combination of medical records, imaging, telephone interviews, and Social Security Death Index. Primary outcomes were in-hospital mortality, stroke, and paraplegia. Secondary outcomes included device-related adverse events (rupture, migration, or endoleak), secondary procedures, open conversion, and all-cause mortality. RESULTS Between September 2005 and July 2012, 82 consecutive patients (57 males, mean [SD] age, 39.5 [20] years; mean [SD] Injury Severity Score [ISS], 34 [9.5]) underwent TEVAR for TAI. A total of 87 devices were implanted: TAG (n = 36), CTAG (n = 12) (WL Gore, Flagstaff, AZ); Talent (n = 29), Valiant (n = 5) (Medtronic, Santa Rosa, CA); TX2 (n = 2) (Cook, Bloomington, IN); and other (n = 3). Left subclavian artery coverage was required in 32 patients (39%). Technical success rate was 100%. Rates of in-hospital mortality, stroke, and paraplegia were 5.0%, 2.4%, and 0%, respectively. Median follow-up time was 2.3 years (range, 0–7 years). The availability of follow-up data was as follows: Social Security Death Index (100%), telephone interview (68%), clinic visit (61%), and imaging (82%). The incidence of device-related adverse events was 2.4%. There were four secondary procedures: two patients underwent a carotid-subclavian bypass, and two had an open conversion for device-related complications. Survival was 95% at 30 days, 88% at 1 year, 87% at 2 years, and 82% at 5 years. CONCLUSION At midterm follow-up, TEVAR is an effective and durable option for the treatment of TAI in properly selected patients. Device-related adverse events, secondary procedures, and open conversion are rare. Follow-up remains a challenge. LEVEL OF EVIDENCE Therapeutic study, level V.

Serum Myoglobin and Renal Morbidity and Mortality following Thoracic and Thoraco-Abdominal Aortic Repair: Does Rhabdomyolysis Play a Role?

OBJECTIVES The intractability of renal dysfunction following thoracic and thoraco-abdominal aortic repair leads us to believe that the accepted mechanisms of renal injury - ischaemia and embolism - are incompletely explanatory. We studied postoperative myoglobinaemia and renal dysfunction following aortic surgery. METHODS Between September 2006 and February 2008, we studied serum myoglobin in 109 patients requiring thoracic/thoraco-abdominal repair for three postoperative days. Forty-two of the 109 (38%) patients were female. The median age was 67 years (range 23-84 years). As we have focussed more attention on renal function, our independent renal consultants have dialysed more aggressively. We divided dialysis into: (1) creatinine indication, (2) non-creatinine indication and (3) no dialysis. RESULTS Thirteen of the 109 (12%) patients met creatinine indication for dialysis (>4 mg dl(-1)) and an additional 28 (26%) were dialysed for other reasons. Overall mortality was 12 out of 109 (11%) cases: 11 out of 41 (27%) in dialysed patients and one out of 68 (1.5%) in non-dialysed patients. Mortality did not differ between the indications for dialysis. Predictors of mortality were baseline glomerular filtration rate (GFR), postoperative myoglobin and dialysis. The only predictor of dialysis was postoperative myoglobin. CONCLUSION A strong relationship between postoperative serum myoglobin and renal failure suggests a rhabdomyolysis-like contributing aetiology following thoraco-abdominal aortic repair. We postulate a novel mechanism of renal injury for which mitigation strategies should be developed.

Progress and Future Challenges in Thoracoabdominal Aortic Aneurysm Management

BackgroundPostoperative paraplegia and paraparesis have been the scourge of thoracoabdominal aortic repair since the inception of the procedure.Methods and ResultsIn our experience with more than 1,250 cases in 15 years, we have developed adjunctive strategies that have pushed neurologic deficit rates down from over 30% percent in the most extensive cases to less than 2% overall in the modern era. The dramatic reductions in risk reported by ourselves and others have led to recent complacency regarding the importance of this complication, and widening use of endovascular technologies raises the potential specter of a return to suboptimal results.ConclusionsUtmost care is required in the vetting of these new technologies to prevent regression of the hard-won excellent results obtainable by open repair. Postoperative renal failure, in stark contrast to neurologic deficit, has remained resistant to every treatment that has been described in the literature. The fact that we haven’t learned to treat it means that we don’t understand the mechanisms behind it, and this problem is worthy of a major focused discovery and management effort. We have recently begun a multi-pronged research program to discover basic mechanisms of renal injury so that appropriate and effective treatments can be discovered.

Endovascular treatment of hemodialysis access pseudoaneurysms

OBJECTIVE Pseudoaneurysm (PSA) formation is a complication of hemodialysis access. Open repair requires PSA resection, interposition graft placement, and insertion of a catheter as a bridge. Endovascular stent graft repair is an alternative that permits immediate use of the access site. The objective of this study was to determine the efficacy of stent grafts for repair of arteriovenous fistula and arteriovenous graft PSA. METHODS A retrospective review of medical records from October 2007 to March 2011 revealed 24 patients with a PSA who underwent endovascular repair using a stent graft. Indications for repair included PSA with symptoms (n = 11), PSA with skin erosion (n = 8), PSA with failed hemodialysis (n = 3), and PSA after balloon angioplasty of a stenosis (n = 2). Outcome measures were technical success, 30-day and 180-day patency, secondary interventions, and complications. All the statistical analyses were conducted by using software SAS 9.1 (SAS, SAS Institute, Gary, NC). RESULTS Twenty-seven self-expanding stent grafts (Viabahn, W. L. Gore, n = 25; Fluency, Bard, n = 2) were used to treat hemodialysis access (arteriovenous graft, n = 13; arteriovenous fistula, n = 11) PSA in 24 patients (16 females; mean age, 55.7 years; mean body mass index, 28.4; mean PSA diameter, 19.5 mm). Comorbidities included hypertension (n = 22; 91.7%), diabetes mellitus (n = 8; 33.3%), and coronary artery disease (n = 4; 16.67%). The median time from access creation to repair was 455 days. The technical success rate was 100%. Balloon angioplasty of an outflow stenosis was performed in 56% of stent grafts. The 30- and 180-day patency rate was 100% and 69.2%, respectively. Three secondary interventions were performed for treatment of unrelated stenosis. Treatment failure occurred in five (18.5%) stent grafts due to infection (n = 3) and thrombosis (n = 2). Treatment of PSA with skin erosion was associated with failure due to infection (odds ratio, 5.0; 95% confidence interval, .38, 66.01). The remaining 22 (81.5%) stent grafts remain patent. The mean follow-up time was 268.9 days (median, 97.5). CONCLUSIONS Endovascular therapy is an effective and durable treatment option for patients with dialysis access PSAs. This technique permits immediate use of the hemodialysis access site as well as identification and treatment of associated stenosis. It may be considered as an alternative to open repair in patients who are anatomically suitable candidates.

In-vivo Imaging of Femoral Artery Nitinol Stents for Deformation Analysis

PURPOSE The authors have developed a direct method to study femoral artery stent deformations in vivo. A previously described imaging and analysis approach based on a calibrated phantom was used to examine stents in human volunteers treated for atherosclerotic disease. In this pilot study, forces on stents were evaluated under different in-vivo flexion conditions. MATERIALS AND METHODS The optimized imaging protocol for imaging with a C-arm computed tomography system was first verified in an in-vivo porcine stent model. Human data were obtained by imaging 13 consenting volunteers with stents in femoral vessels. The affected leg was imaged in straight and bent positions to observe stent deformations. Semiautomatic software was used to calculate the changes in bending, extension, and torsion on the stents for the two positions. RESULTS For the human studies, tension and bending calculation were successful. Bending was found to compress stent lengths by 4% ± 3% (-14.2 to 1.5 mm), increase their average eccentricity by 10% ± 9% (0.12 to -0.16), and change their mean curvature by 27% ± 22% (0 to -0.005 mm(-1)). Stents with the greatest change in eccentricity and curvature were located behind the knee or in the pelvis. Torsion calculations were difficult because the stents were untethered and are symmetric. In addition, multiple locations in each stent underwent torsional deformations. CONCLUSIONS The imaging and analysis approach developed based on calibrated in vitro measurements was extended to in-vivo data. Bending and tension forces were successfully evaluated in this pilot study.

Update on blunt thoracic aortic injury: Fifteen-year single-institution experience

OBJECTIVES Despite improvements in the management of blunt thoracic aortic injury, mortality remains high. We report our experience with blunt thoracic aortic injury at a level 1 trauma center over the past 15 years. METHODS Between January 1, 1997, and January 1, 2012, data on 338 patients who presented with suspected blunt thoracic aortic injury were entered into the University of Texas Medical School at Houston Trauma Center Registry. A total of 175 patients (52%) underwent thoracic aortic repair; 29 (17%) had open repair with aortic crossclamping, 77 (44%) had open repair with distal aortic perfusion, and 69 (39%) had thoracic endovascular aortic repair. Outcomes were determined, including early mortality, morbidity, length of stay, and late survival. Multiple logistic regression analysis was used to compute adjusted estimates for the effects of the operative technique. RESULTS The early mortality for all patients with blunt thoracic aortic injury was 41% (139/338). Early mortality was 17% (27/175) for operative aortic interventions, 4% (3/69) for thoracic endovascular aortic repairs, 31% (11/29) for open repairs with aortic crossclamping, and 14% (11/77) for open repairs with distal aortic perfusion. Survival for thoracic endovascular aortic repair at 1 year and 5 years was 92% and 87%, respectively. Survival for open repair at 1, 5, 10, and 15 years was 76%, 75%, 72%, and 68%, respectively. CONCLUSIONS Blunt thoracic aortic injury remains associated with significant early mortality. Delayed selective management, when applied with open repair with distal aortic perfusion and the use of thoracic endovascular aortic repair, has been associated with improved early outcomes. The long-term durability of thoracic endovascular aortic repair is unknown, necessitating close radiographic follow-up.