Melissa L. Kirkwood

Surgeon education decreases radiation dose in complex endovascular procedures and improves patient safety

OBJECTIVE Complex endovascular procedures such as fenestrated endovascular aneurysm repair (FEVAR) are associated with higher radiation doses compared with other fluoroscopically guided interventions (FGIs). The purpose of this study was to determine whether surgeon education on radiation dose control can lead to lower reference air kerma (RAK) and peak skin dose (PSD) levels in high-dose procedures. METHODS Radiation dose and operating factors were recorded for FGI performed in a hybrid room over a 16-month period. Cases exceeding 6 Gy RAK were investigated according to institutional policy. Information obtained from these investigations led to surgeon education focused on reducing patient dose. Points addressed included increasing table height, utilizing collimation and angulation, decreasing magnification modes, and maintaining minimal patient-to-detector distance. Procedural RAK doses and operating factors were compared 8 months pre- (group A) and 8 months post- (group B) educational intervention using analysis of variance with Tukey pairwise comparisons and t-tests. PSD distributions were calculated using custom software employing input data from fluoroscopic machine logs. RESULTS Of 447 procedures performed, 300 FGIs had sufficient data to be included in the analysis (54% lower extremity, 11% thoracic endovascular aneurysm repair, 10% cerebral, 8% FEVAR, 7% endovascular aneurysm repair, 5% visceral, and 5% embolization). Twenty-one cases were investigated for exceeding 6 Gy RAK. FEVAR comprised 70% of the investigated cases and had a significantly higher median RAK dose compared with all other FGIs (P < .0001). There was no difference in body mass index between groups A and B; however, increasing body mass index was an indicator for increased RAK. PSD calculations were performed for the 122 procedures that focused on the thorax and abdomen (group A, 80 patients; group B, 42 patients). Surgeon education most strongly affected table height, with an average table height elevation of 10 cm per case after education (P < .0001). The dose index (PSD/RAK ratio) was used to track changes in operating practices, and it decreased from 1.14 to 0.79 after education (P < .0001). These changes resulted in an estimated 16% reduction in PSD. There was a trend toward a decrease in patient to detector distance, and the use of collimation increased from 25% to 40% (P < .001) for all cases; however, these did not result in a decrease in PSD. The number of cases that exceeded 6 Gy RAK did not change after education; however, the proportion of non-FEVAR cases that exceeded 6 Gy decreased from 40% to 20%. CONCLUSIONS Surgeon education on the appropriate use of technical factors during FGIs improved operating practice, reduced patient radiation dose, and decreased the number of non-FEVAR cases that exceeded 6 Gy. It is essential that vascular surgeons be educated in best operating practices to lower PSD; nonetheless, FEVAR remains a high-dose procedure.

Optimal medical therapy predicts amputation-free survival in chronic critical limb ischemia

OBJECTIVE Determine the proportion of patients with chronic critical limb ischemia (CLI) who failed to adhere to Trans-Atlantic Inter-Society Consensus II guidelines of medical therapy and to quantify the effect of baseline suboptimal medical management on amputation-free survival (AFS). METHODS The patients were identified from a prospectively maintained database of consecutive patients presenting with CLI to the Vascular Surgery service at a single hospital. The primary outcome variable was AFS. The effects of baseline demographics, comorbid medical conditions, ambulatory status, optimal medical management, and Rutherford classification were assessed. Significant univariate predictors (P < .10) of AFS were entered into a multivariate Cox proportional hazards model. RESULTS From August 1, 2010 through January 1, 2012, 98 patients (median age, 59.0; interquartile range, 53, 64 years; 58 men) were evaluated with rest pain (n = 40) or tissue loss (n = 58). Optimal medical management was identified in 31 (32%) patients at initial presentation. Compliance rates for the entire cohort were 61% for statin use, 69% for antiplatelet therapy, 56% for angiotensin-converting enzyme inhibitor use, and 53% for beta-blocker use. Significant univariate predictors of major amputation or death included: Rutherford classification (hazard ratio [HR], 1.56; 95% confidence interval [CI], 1.01-2.41; P = .04); nonambulatory status (HR, 2.17; 95% CI, 1.68-2.81; P < .01); unrevascularized patients (HR, 2.77; 95% CI, 1.32-5.85; P < .01); a history of tobacco abuse (HR, 1.49; 95% CI, 0.57-3.86; P = .09); a history of end-stage-renal disease (HR, 7.97; 95% CI, 3.10-20.52; P < .01); suboptimal medical management (HR, 4.25; 95% CI, 1.28-14.07; P = .02); and an absence of antiplatelet agents (HR, 1.94; 95% CI, 0.92-4.11; P = .08). Independent predictors of major amputation or death included: initial nonambulatory status (HR, 2.43; 95% CI, 1.03-2.05; P < .01); unrevascularized status (HR, 2.43; 95% CI, 1.76-3.34; P = .01); and suboptimal medical management at presentation (HR, 8.54; 95% CI, 2.05-35.65; P < .01). CONCLUSIONS Despite guidelines advocating the optimization of atherosclerotic risk factors, less than one-third of patients with CLI present with their risk factors optimally managed. Patients who are medically undertreated have an eight-fold risk of major amputation and/or death. The magnitude of the effect suggests that future trials and quality assessments should stratify outcomes by the quality of baseline medical management. Of the risk factors affecting AFS medical therapy optimization is the variable that can be most significantly improved by vascular surgeons and the medical community.

Aneurysmal iliac arteries do not portend future iliac aneurysmal enlargement after endovascular aneurysm repair for abdominal aortic aneurysm

OBJECTIVES The purpose of this study was to examine the fate of aneurysmal iliac arteries managed during endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA). METHODS We analyzed data from the Cook Zenith trial. Follow-up was at 1 month, 6 months, 12 months, and then annually for 5 years. Patients were evaluated according to the largest iliac artery diameter: group A (≥ 20 mm) and group B (< 20 mm). These groups were further subdivided based on iliac artery growth ≥ 5 mm during follow-up. The Fisher exact test and χ(2) test were used. RESULTS Of 736 patients treated, 671 had a follow-up examination (group A = 274). In group A, 220 (80%) were treated with flared limbs in the common iliac artery. Group A did not demonstrate increased iliac growth as compared to group B. Furthermore, both groups had a similar percentage of patients that experienced iliac artery expansion of 32.1% and 31.5%, respectively. Extension to the external iliac artery did not affect growth (P = .4). No difference was noted in the need for secondary interventions between groups. However, group A patients that did not experience growth were more likely to develop a distal type I endoleak than group B patients who did not develop growth (P = .03). There was no difference in serious adverse events (SAEs) between groups (P = .51). However, patients that developed iliac artery growth in either group were less likely to have an SAE compared to patients who did not experience growth (P = .035). There was no difference in the mean percent oversizing of the iliac limbs between groups A and B. However, the mean percent oversizing in groups A and B that had iliac artery growth was significantly higher than in those that demonstrated no growth (P < .01). CONCLUSION Aneurysmal iliac arteries managed by flared limbs or external iliac extensions at the time of EVAR for AAA do not demonstrate future iliac growth, increased rate of secondary interventions, or SAEs compared to patients with normal iliac arteries. This suggests that aneurysmal iliac arteries can be safely treated with appropriately sized limbs landed in the common or external iliac artery.

Radiation-induced skin injury after complex endovascular procedures

BACKGROUND Radiation-induced skin injury is a serious potential complication of fluoroscopically guided interventions. Transient erythema occurs at doses of 2 to 5 Gy, whereas permanent epilation, ulceration, and desquamation are expected at doses above this level. Complex endovascular procedures (CEPs), such as fenestrated endovascular aortic aneurysm repair (FEVAR), are associated with high radiation doses, yet the prevalence of radiation-induced skin injury is unknown. We hypothesized that skin injury after these exposures is likely to be underrecognized and underreported. This study examined the frequency and severity of deterministic effects and evaluated patient characteristics that might predispose to radiation injury in CEP. METHODS CEP was defined as a procedure with a radiation dose ≥5 Gy (National Council on Radiation Protection and Measurements threshold for substantial radiation dose level [SRDL]). Radiation dose and operating factors were recorded for all CEPs performed in a hybrid room during a 30-month period. Patient medical records were retrospectively reviewed for evidence of skin injury. Patients were seen in follow-up daily until discharge and then at weeks 2 and 6, months 3 and 6, and 1 year. Phone interviews were conducted to determine the presence of any skin-related complaints. Peak skin dose (PSD) distributions were calculated for FEVARs with custom software employing input data from fluoroscopic machine logs. These calculations were validated against Gafchromic film (Ashland Inc, Covington, Ky) measurements. Dose was summed for the subset of patients with multiple procedures within 6 months of the SRDL event, consistent with Joint Commission recommendations. RESULTS Sixty-one CEPs reached a reference air kerma (RAK) of 5 Gy (50 FEVARs, six embolizations, one thoracic endovascular aortic repair, one endovascular aneurysm repair, one carotid intervention, and two visceral interventions). The patient cohort was 79% male and had a mean body mass index of 31. The average RAK was 8 ± 2 Gy (5.0-15.9 Gy). Sixteen patients had multiple CEPs within 6 months of the SRDL event, with a mean cumulative RAK of 12 ± 3 Gy (7.0-18.4 Gy). The mean FEVAR PSD was 6.6 ± 3.6 Gy (3.7-17.8 Gy), with a mean PSD/RAK ratio of 0.78. Gafchromic film dose measurements were not statistically different from PSD estimations, with a constant of proportionality of 0.99. Three patients were lost to follow-up before their first postoperative visit. No radiation skin injuries were found. CONCLUSIONS This study represents the largest analysis of deterministic skin injury after CEPs, and our results suggest that it is less frequent than expected and not increased in CEPs.

Thoracic Aortic Endograft Explant: A Single-Center Experience

Objectives: We report our experience following thoracic aortic endovascular repair (TEVAR) explant. Methods: A total of 500 TEVARs were performed from 1999 to 2009, with 4 requiring explant. Chart review was performed to identify the indications of explant, operative technique, and perioperative morbidity and mortality. Results: Indications of graft removal included device maldeployment, type I endoleak, aortoenteric fistula, and retrograde type A dissection necessitating aortic root replacement. Reconstruction was achieved with aortic homograft, Dacron, or explant of the proximal component with incorporation of the distal stent into the suture line. Mean follow-up was 13 months (0-50 months). Paraplegia and perioperative death occurred in 1 patient who underwent intraoperative conversion to open repair. There were no other major complications, and graft removal was achieved in all patients. Conclusions: Although rare, familiarity with TEVAR explant is imperative as it is increasingly performed for broader indications. Our limited data suggest that explant can be performed successfully albeit with morbidity.

The Use of Arterial Closure Devices for Incidental Arterial Injury

Incidental arterial injury is one of the main mechanical complications associated with central venous catheter placement. These injuries can result in significant morbidity and mortality. The use of arterial closure devices to repair these injuries offers a less invasive alternative than open repair and a safer approach than manual compression. We present 3 cases of critically ill patients treated with arterial closure devices when attempted central venous catheterization failed and inadvertent arterial cannulation occurred. A brief review of the various closure devices and there indications is discussed.

Simultaneous thoracic endovascular aortic repair and endovascular aortic repair is feasible with minimal morbidity and mortality.

OBJECTIVE To determine the results of simultaneous thoracic endovascular aortic repair (TEVAR) and endovascular aneurysm repair (EVAR). METHODS Records were retrospectively reviewed. Eight patients underwent simultaneous TEVAR and EVAR between 1999 and 2010 at a single center. All patients had concomitant thoracic and abdominal aortic disease (aneurysms, penetrating aortic ulcers). Ranges for the thoracic and abdominal aneurysm diameters were 6.0 to 9.1 cm and 5.0 to 7.6 cm, respectively. Four patients were treated emergently, and the remainder had indications for simultaneous repair. The mean age was 72 years (six males). All patients had significant comorbidities. RESULTS Average procedural time was 173 minutes ± 25 minutes. Spinal drainage and neuromonitoring was used in all cases. Thoracic endovascular aortic repair (TEVAR) was performed prior to EVAR. Three patients required left subclavian coverage and four patients had full coverage of the thoracic aorta. Only one patient had internal iliac artery (unilateral) coverage. One patient was lost to follow-up 6 weeks following discharge. The remainder were followed between 4 and 77 months postoperatively. No patients developed acute myocardial infarction, acute renal failure, or neurologic complications, including permanent paralysis or stroke. One patient developed transient lower extremity weakness that resolved with blood pressure augmentation. Mean blood loss was 325 mL ± 137 mL. The average intensive care unit and hospital stay was 3 days and 8 days, respectively. In follow-up, one patient developed a type II endoleak that was successfully embolized. CONCLUSION Combined TEVAR and EVAR can be performed successfully with minimal morbidity and mortality. In particular, in this limited series of eight patients, there have been no occurrences of lower extremity paralysis or renal failure despite a high proportion of emergent cases. When anatomically feasible, simultaneous TEVAR and EVAR can be considered as a viable alternative to staged or hybrid repair.

Deterministic effects after fenestrated endovascular aortic aneurysm repair.

BACKGROUND Endovascular aortic aneurysm repairs (EVARs) with fenestrated (FEVAR) stent grafts are high radiation dose cases, yet no skin injuries were found retrospectively in our 61 cases with a mean peak skin dose (PSD) of 6.8 Gy. We hypothesize that skin injury is under-reported. This study examined deterministic effects in FEVARs after procedural changes implemented to detect skin injury. METHODS All FEVARs during a 6-month period with a radiation dose of 5 Gy reference air kerma (RAK; National Council on Radiation Protection and Measurements threshold for substantial radiation dose level [SRDL]) were included. Patients were questioned about skin erythema, epilation, and necrosis, with a physical examination of the back completed daily until discharge and then at 2 and 4 weeks and at 3 and 6 months. PSD distributions were calculated with custom software using input data from fluoroscopic machine logs. These calculations have been validated against Gafchromic (Ashland Inc, Covington, Ky) film measurements. Dose was summed for the subset of patients with multiple procedures ≤6 months of the SRDL event, consistent with the joint commission recommendations. RESULTS Twenty-two patients, 21 FEVARs and one embolization, reached an RAK of 5 Gy. The embolization procedure was excluded from review. The average RAK was 7.6 ± 2.0 Gy (range, 5.1-11.4 Gy), with a mean PSD of 4.8 ± 2.0 Gy (range, 2.3-10.4 Gy). Fifty-two percent of patients had multiple endovascular procedures ≤6 months of the SRDL event. The mean RAK for this subset was 10.0 ± 2.9 Gy (range, 5.5-15.1 Gy), with a mean PSD of 6.6 ± 1.9 Gy (range, 3.4-9.4 Gy). One patient died before the first postoperative visit. No radiation skin injuries were found. Putative risk factors for skin injury were evaluated and included smoking (32%), diabetes (14%), cytotoxic drugs (9%), and fair skin type (91%). No other risk factors were present (hyperthyroidism, collagen vascular disorders). CONCLUSIONS Deterministic skin injuries are uncommon after FEVAR, even at high RAK levels, regardless of cumulative dose effects. This study addresses the concern of missed injuries based on the retrospective clinical examination findings that were published in our previous work. Even with more comprehensive postoperative skin examinations and patient questioning, the fact that no skin injuries were found suggests that radiation-induced skin injuries are multifactorial and not solely dose dependent.

Surgeon radiation dose during complex endovascular procedures

BACKGROUND Surgeon radiation dose during complex fluoroscopically guided interventions (FGIs) has not been well studied. We sought to characterize radiation exposure to surgeons during FGIs based on procedure type, operator position, level of operator training, upper vs lower body exposure, and addition of protective shielding. METHODS Optically stimulable, luminescent nanoDot (Landauer, Inc, Glenwood, Ill) detectors were used to measure radiation dose prospectively to surgeons during FGIs. The nanoDot dosimeters were placed outside the lead apron of the primary and assistant operators at the left upper chest and left lower pelvis positions. For each case, the procedure type, the reference air kerma, the kerma-area product, the relative position of the operator, the level of training of the fellow, and the presence or absence of external additional shielding devices were recorded. Three positions were assigned on the right-hand side of the patient in decreasing relative proximity to the flat panel detector (A, B, and C, respectively). Position A (main operator) was closest to the flat panel detector. Position D was on the left side of the patient at the brachial access site. The nanoDots were read using a microSTARii medical dosimetry system (Landauer, Inc) after every procedure. The nanoDot dosimetry system was calibrated for scattered radiation in an endovascular suite with a National Institute of Standards and Technology traceable solid-state radiation detector (Piranha T20; RTI Electronics, Fairfield, NJ). Comparative statistical analysis of nanoDot dose levels between categories was performed by analysis of variance with Tukey pairwise comparisons. Bonferroni correction was used for multiple comparisons. RESULTS There were 415 nanoDot measurements with the following case distribution: 16 thoracic endovascular aortic repairs/endovascular aneurysm repairs, 18 fenestrated endovascular aneurysm repairs (FEVARs), 13 embolizations, 41 lower extremity interventions, 10 fistulograms, 13 visceral interventions, and 3 cerebrovascular procedures. The mean operator effective dose for FEVARs was higher than for other case types (P < .03), 20 μSv at position A and 9 μSv at position B. For all case types, position A (9.0 μSv) and position D (20 μSv) received statistically higher effective doses than position B (4 μSv) or position C (0.4 μSv) (P < .001). However, the mean operator effective dose for position D was not statistically different from that for position A. The addition of the lead skirt significantly decreased the lower body dose (33 ± 3.4 μSv to 6.3 ± 3.3 μSv) but not the upper body dose (6.5 ± 3.3 μSv to 5.7 ± 2.2 μSv). Neither ceiling-mounted shielding nor level of fellow training affected operator dose. CONCLUSIONS Surgeon radiation dose during FGIs depends on case type, operator position, and table skirt use but not on the level of fellow training. On the basis of these data, the primary operator could perform approximately 12 FEVARs/wk and have an annual dose <10 mSv, which would not exceed lifetime occupational dose limits during a 35-year career. With practical case loads, operator doses are relatively low and unlikely to exceed occupational limits.

Anterior Tibial Artery Pseudoaneurysm following Ankle Arthroscopy in a Hemophiliac Patient

Arthroscopy of the foot and ankle is a common orthopedic procedure with low complication rates. Arterial injuries from these procedures are an even more rare subset of the complications. Hemophilia A is a genetic disorder of aberrant coagulation, which leads to increased risk of bleeding even after minor trauma. We present the second case of anterior tibial artery pseudoaneurysm formation secondary to ankle arthroscopy in a hemophiliac patient and suggest that these individuals are at higher risk for developing complications associated with arterial injury. Furthermore, potential risk factors include port placement, anatomic variation of the vessels, and nature of the arthroscopic procedure. We recommend steps to prevent complications in hemophiliac patients.