Amir F. Azarbal

Utility of direct angiosome revascularization and runoff scores in predicting outcomes in patients undergoing revascularization for critical limb ischemia

OBJECTIVE Both runoff scores and direct (DR) vs indirect revascularization (IR) according to pedal angiosomes have unclear impact on outcome for patients with critical limb ischemia (CLI). We compared DR vs IR and runoff scores in CLI patients undergoing infrapopliteal bypass for foot wounds. METHODS Patients who had tibial/pedal bypass for a foot/ankle wound from 2005-2011 were identified and operations classified as DR or IR based on wound location and bypass target. A blinded observer reviewed angiograms for an intact pedal arch and calculated standard Society for Vascular Surgery (single tibial) and modified (composite tibial) runoff scores. Comorbidities, wound characteristics, wound healing, major amputation, and overall survival were determined. RESULTS A total of 106 limbs were revascularized in 97 patients; 54 limbs had DR and 52 had IR, although only 36% of wounds corresponded to a single, distinct angiosome. Wound characteristics and comorbidities were similar between groups. Mean standard (7.9 vs 7.2; P = .001) and modified (22.2 vs 20.0; P = .02) runoff scores were worse (higher number indicates worse runoff) in the IR vs DR groups; 33% had a complete pedal arch. Complete wound healing (78% vs 46%; P = .001) and time to complete healing (99 vs 195 days; P = .002) were superior with DR vs IR but were not influenced by runoff score, modified runoff score or presence of complete plantar arch. In multivariate models controlling for runoff score, DR remained a significant predictor for wound healing (odds ratio, 2.9; 95% confidence interval, 1.1-7.4; P = .028) and reduced healing time (hazard ratio, 2.1; 95% confidence interval, 1.2-3.7; P = .012). Mean amputation-free survival (75 vs 71 months for DR vs IR; P = .82) and median survival (36 vs 33 months DR vs IR; P = .22) were not different for DR vs IR. CONCLUSIONS DR according to pedal angiosomes provides more efficient wound healing, but is possible in only one-half of the patients and does not affect amputation-free or overall survival. DR is associated with improved runoff scores, but current runoff scores have little clinical utility in predicting outcomes in CLI patients.

Compliance With Long-Term Surveillance Recommendations Following Endovascular Aneurysm Repair or Type B Aortic Dissection

OBJECTIVE Lifelong surveillance is recommended for both endovascular aneurysm repair and acute, uncomplicated type B thoracic aortic dissection, though compliance remains a significant challenge. We sought to determine factors associated with failure to obtain recommended surveillance. METHODS Patients surviving to discharge who had endovascular repair of thoracic (thoracic endovascular aortic aneurysm repair [TEVAR]) or abdominal aortic aneurysms (endovascular aortic aneurysm repair [EVAR]) or medical management for type B dissections from 2004-2011 were reviewed. Primary end points were compliance with follow-up and need for reintervention. Comorbidities examined included coronary artery disease, congestive heart failure, hypertension, chronic obstructive pulmonary disease, diabetes, and chronic kidney disease. Socioeconomic factors examined were age, sex, distance from hospital, discharge destination (ie, home or skilled nursing facility), and insurance type. Endoleak and sac expansion were recorded, as were complications, including endograft migration, infection or thrombosis, and aneurysm degeneration. RESULTS Two hundred four patients, median age 71.9 years, were identified; 171 had EVAR and 33 had type B dissection. EVAR patients included 45 thoracic, 100 abdominal, and 12 thoracoabdominal endografts, as well as 7 iliac artery aneurysm repairs and 7 proximal/distal graft extensions. Median follow-up was 28 ± 10.5 months. Overall, 56% were lost to follow-up, whereas 11% never returned for surveillance after initial hospitalization. Follow-up was compared for each of the comorbidities and socioeconomic factors; none were found to significantly affect follow-up. The known complication rate was 9.3% (n = 19), with reintervention performed in 14% of EVAR/TEVAR patients. Thirty-eight percent of medically managed patients with type B dissections eventually required surgical intervention. All-cause 5-year mortality was 27% as determined by the Social Security Death Index. CONCLUSIONS Despite a significant rate of reintervention following EVAR, TEVAR, and type B dissection, long-term compliance with surveillance is limited. In addition, predicting who is at risk of being lost to follow-up remains difficult. If current recommendations for lifelong surveillance are to be followed, coordinated protocols are required to capture EVAR, TEVAR, and type B dissection patients to ensure optimal follow-up for these patients. However, the lack of survival benefit in those with complete follow-up suggests that further study is needed with regard to ideal duration of long-term follow-up.

The contemporary management of renal artery aneurysms

BACKGROUND Renal artery aneurysms (RAAs) are rare, with little known about their natural history and growth rate or their optimal management. The specific objectives of this study were to (1) define the clinical features of RAAs, including the precise growth rate and risk of rupture, (2) examine the current management and outcomes of RAA treatment using existing guidelines, and (3) examine the appropriateness of current criteria for repair of asymptomatic RAAs. METHODS A standardized, multi-institutional approach was used to evaluate patients with RAAs at institutions from all regions of the United States. Patient demographics, aneurysm characteristics, aneurysm imaging, conservative and operative management, postoperative complications, and follow-up data were collected. RESULTS A total of 865 RAAs in 760 patients were identified at 16 institutions. Of these, 75% were asymptomatic; symptomatic patients had difficult-to-control hypertension (10%), flank pain (6%), hematuria (4%), and abdominal pain (2%). The RAAs had a mean maximum diameter of 1.5 ± 0.1 cm. Most were unilateral (96%), on the right side (61%), saccular (87%), and calcified (56%). Elective repair was performed in 213 patients with 241 RAAs, usually for symptoms or size >2 cm; the remaining 547 patients with 624 RAAs were observed. Major operative complications occurred in 10%, including multisystem organ failure, myocardial infarction, and renal failure requiring dialysis. RAA repair for difficult-to-control hypertension cured 32% of patients and improved it in 26%. Three patients had ruptured RAA; all were transferred from other hospitals and underwent emergency repair, with no deaths. Conservatively treated patients were monitored for a mean of 49 months, with no acute complications. Aneurysm growth rate was 0.086 cm/y, with no difference between calcified and noncalcified aneurysms. CONCLUSIONS This large, contemporary, multi-institutional study demonstrated that asymptomatic RAAs rarely rupture (even when >2 cm), growth rate is 0.086 ± 0.08 cm/y, and calcification does not protect against enlargement. RAA open repair is associated with significant minor morbidity, but rarely a major morbidity or mortality. Aneurysm repair cured or improved hypertension in >50% of patients whose RAA was identified during the workup for difficult-to-control hypertension.

A modern series of acute aortic occlusion.

OBJECTIVE Acute aortic occlusion (AAO) is a rare condition associated with substantial morbidity and mortality. The most recent large series was published over 15 years ago and included patients from the 1980s. Previous studies reported up to 50% of AAOs are caused by embolization, with a mortality rate approaching 50%. We reviewed our recent experience with AAOs to identify current etiologies and outcomes in a contemporary series of patients with AAOs. METHODS Current Procedural Terminology codes and data from a prospectively maintained vascular surgical database were used to identify patients with acute occlusion of the native aorta between 2005 and July 2013. AAOs secondary to trauma, dissection, or graft occlusion were excluded. RESULTS We identified 29 patients with AAOs treated at our institution. Twenty-three patients were transferred from referring hospitals with a mean transfer time of 3.9 hours (range, 0.5-7.5 hours). Twenty-two presented with occlusion below the renal arteries and seven with occlusion extending above the renal arteries. Resting motor/sensory lower extremity deficits were noted in 17 patients. Eight patients presented with complete paraplegia. Etiology was felt to be aortoiliac thrombosis in 22 cases, embolic occlusion in 2, and indeterminate in 5. Surgical revascularization was performed in 26 cases (extra-anatomic bypass in 18, thromboembolectomy in 5, and aortobifemoral bypass in 3 patients. Three patients had no intervention. Acute renal failure developed in 15 patients and rhabomyolysis in 10 patients. Fasciotomy was performed in 19 extremities. Nine extremities were amputated in six patients. Overall mortality was 34% with a 30-day mortality of 24% and a postprocedure mortality of 15%. CONCLUSIONS AAO is an infrequent but devastating event. The dominant etiology of AAOs is now thrombotic occlusion. Despite advances in vascular surgery and critical care over the past 2 decades, associated morbidity and mortality remain substantial with high rates of limb loss, acute renal failure, rhabdomyolysis, and death. Mortality may be improved with expeditious extra-anatomic bypass.

Improving the Efficiency of Abdominal Aortic Aneurysm Wall Stress Computations

An abdominal aortic aneurysm is a pathological dilation of the abdominal aorta, which carries a high mortality rate if ruptured. The most commonly used surrogate marker of rupture risk is the maximal transverse diameter of the aneurysm. More recent studies suggest that wall stress from models of patient-specific aneurysm geometries extracted, for instance, from computed tomography images may be a more accurate predictor of rupture risk and an important factor in AAA size progression. However, quantification of wall stress is typically computationally intensive and time-consuming, mainly due to the nonlinear mechanical behavior of the abdominal aortic aneurysm walls. These difficulties have limited the potential of computational models in clinical practice. To facilitate computation of wall stresses, we propose to use a linear approach that ensures equilibrium of wall stresses in the aneurysms. This proposed linear model approach is easy to implement and eliminates the burden of nonlinear computations. To assess the accuracy of our proposed approach to compute wall stresses, results from idealized and patient-specific model simulations were compared to those obtained using conventional approaches and to those of a hypothetical, reference abdominal aortic aneurysm model. For the reference model, wall mechanical properties and the initial unloaded and unstressed configuration were assumed to be known, and the resulting wall stresses were used as reference for comparison. Our proposed linear approach accurately approximates wall stresses for varying model geometries and wall material properties. Our findings suggest that the proposed linear approach could be used as an effective, efficient, easy-to-use clinical tool to estimate patient-specific wall stresses.

Open versus endoscopic great saphenous vein harvest for lower extremity revascularization of critical limb ischemia

OBJECTIVE This study determined wound complication rates, intervention rates, failure mechanisms, patency, limb salvage, and overall survival after lower extremity revascularization using open vein harvest (OVH) vs endoscopic vein harvest (EVH) for critical limb ischemia. METHODS A single-institution review was conducted of consecutive patients who underwent infrainguinal bypass with a single-segment reversed great saphenous vein between 2005 and 2012. RESULTS A total of 251 patients with critical limb ischemia underwent revascularization, comprising 153 with OVH and 98 with EVH. The OVH group had a lower mean body mass index (26.7 vs 29.9 kg/m(2); P = .001). There were no other differences in demographics, comorbidities, medications, smoking, or in the proximal or distal anastomotic site. Median operative times were 249 minutes (OVH) vs 316 minutes (EVH; P < .001). Median postoperative hospital length of stay was 7 days (OVH) vs 5 days (EVH; P < .001). Median follow-up was 295 days (OVH) vs 313 days (EVH; P = .416). During follow-up, 21 OVH grafts (14%) and 27 EVH grafts (28%) underwent an intervention (P = .048). There were a similar number of surgical interventions: 50% (OVH) vs 61% (EVH; P = .449). Failed grafts had a mean of 1.2 stenoses per graft, regardless of harvest method. Median stenosis length was 2.1 cm (OVH) vs 2.5 cm (EVH; P = .402). At 1 and 3 years, the primary patency was 71% and 52% (OVH) vs 58% and 41% (EVH; P = .010), and secondary patency was 88% and 71% (OVH) vs 88% and 64% (EVH; P = .266). A secondary patency Cox proportional hazard model showed EVH had a hazard ratio of 2.93 (95% confidence interval, 1.03-8.33; P = .044). Overall and harvest-related wound complications were 44% and 29% (OVH) vs 37% and 12% (EVH; P = .226 and P = .002). At 5 years, amputation-free survival was 48% (OVH) vs 54% (EVH; P = .305), and limb salvage was 89% (OVH) and 91% (EVH; P = .615). CONCLUSIONS OVH and EVH have similar failure mechanisms, limb salvage, amputation-free survival, and overall survival. EVH is associated with impaired patency, increased need for intervention, longer operative times, shorter hospital stays, and decreased vein harvest site wound complications. OVH of the great saphenous vein may provide optimal patency but was not necessarily associated with better patient-centered outcomes. Similar limb salvage rates and amputation-free survival may justify the use of EVH, despite inferior patency, to capture shorter hospital stays and decreased wound complications.

Antiplatelet therapy for peripheral arterial disease and critical limb ischemia: guidelines abound, but where are the data?

Antiplatelet therapy is invariably prescribed for patients with peripheral arterial disease and critical limb ischemia, and numerous major society guidelines espouse their use, but high-quality data in this high-risk and challenging patient population are often lacking. This article summarizes the major guidelines for antiplatelet therapy, reviews the major studies of antiplatelet therapy in peripheral arterial disease (including data for aspirin, clopidogrel, dipyridamole, cilostazol, and prostanoids), and offers perspective on the potential benefits of ticagrelor, vorapaxar, and rivaroxaban. The review concludes with a discussion of the relative lack of efficacy that antiplatelet therapy has shown in regard to peripheral vascular outcomes.

The Natural History of Indeterminate Blunt Cerebrovascular Injury

IMPORTANCE The Denver criteria grade blunt cerebrovascular injuries (BCVIs) but fail to capture many patients with indeterminate findings on initial imaging. OBJECTIVE To evaluate outcomes and clinical significance of indeterminate BCVIs (iBCVIs). DESIGN, SETTING, AND PARTICIPANTS A retrospective review of all patients treated for BCVIs at our institution from January 1, 2007, through July 31, 2014, was completed. Patients were divided into 2 groups: those with true BCVIs as defined by the Denver criteria and those with iBCVIs, which was any initial imaging suggestive of a cerebrovascular arterial injury not classifiable by the Denver criteria. MAIN OUTCOMES AND MEASURES Primary outcomes were rate of resolution of iBCVIs, freedom from cerebrovascular accident (CVA) or transient ischemic attack (TIA), and 30-day mortality. RESULTS We identified 100 patients with 138 BCVIs: 79 with true BCVIs and 59 with iBCVIs. With serial imaging, 23 iBCVIs (39.0%) resolved and 21 (35.6%) remained indeterminate, whereas 15 (25.4%) progressed to true BCVI. The rate of CVA or TIA in the iBCVI group was 5.1% compared with 15.2% in the true BCVI group (P = .06). Of the 15 total CVAs or TIAs, 11 (73.3%) resulted from carotid injury and 4 (26.7%) from vertebral artery occlusion (P = .03). By Kaplan-Meier analysis, there was no difference in freedom from CVA or TIA for the 2 groups (P = .07). Median clinical follow-up was 91 days. Overall and 30-day mortality for the entire series were 17.4% and 15.2%, respectively. There was no difference in long-term or 30-day mortality between true BCVI and iBCVI groups. CONCLUSIONS AND RELEVANCE Detection of iBCVI has become a common clinical conundrum with improved and routine imaging. Indeterminate BCVI is not completely benign, with 25.4% demonstrating anatomical progression to true BCVI and 5.1% developing cerebrovascular symptoms. We therefore recommend serial imaging and antiplatelet therapy for iBCVI.

Duplex ultrasound screening detects high rates of deep vein thromboses in critically ill trauma patients.

OBJECTIVE American College of Chest Physician (ACCP) guidelines stratify deep venous thrombosis (DVT) risk in trauma patients based on injury pattern and pharmacologic prophylaxis. Screening is only recommended for patients with high-risk injuries who are unable to receive pharmacologic prophylaxis. However, the prevalence of lower extremity DVT (LEDVT) in trauma patients may be higher than reported in previous studies as many studies on DVT screening have not investigated calf vein DVTs (CVDVT) and have not exclusively targeted critically ill patients. Given that current ACCP guidelines recommend treatment of CVDVTs, we investigated the efficacy of duplex ultrasound (DUS) screening in critically ill trauma patients for all LEDVTs, including CVDVT, regardless of injury pattern, risk factors, or pharmacologic prophylaxis. METHODS Medical records of 264 intensive care unit trauma patients who received DUS screening for LEDVT were retrospectively examined for the presence of injuries conferring high risk for LEDVT, patient specific DVT risk factors, and low molecular weight heparin (LMWH) prophylaxis. RESULTS Forty (15.2%) patients had LEDVTs found on DUS screening, 24 (60%) were CVDVT, and 30% of all DVTs were diagnosed within 1 week of admission. Patients without high-risk injuries receiving LMWH had a 13.5% DVT rate, which did not differ significantly from the 19.7% DVT rate in high-risk injury patients not receiving LMWH (P = .667). CONCLUSIONS Lower extremity DVT is common in critically ill trauma patients, particularly in the first week following injury, regardless of injury pattern, DVT risk factors, or pharmacologic prophylaxis. Previous studies have underestimated DVT rates by not investigating CVDVTs and not exclusively targeting critically ill patients. We recommend early and continued DUS DVT screening of all critically ill trauma patients.

Intraluminal thrombus is associated with early rupture of abdominal aortic aneurysm

Background: The implications of intraluminal thrombus (ILT) in abdominal aortic aneurysm (AAA) are currently unclear. Previous studies have demonstrated that ILT provides a biomechanical advantage by decreasing wall stress, whereas other studies have associated ILT with aortic wall weakening. It is further unclear why some aneurysms rupture at much smaller diameters than others. In this study, we sought to explore the association between ILT and risk of AAA rupture, particularly in small aneurysms. Methods: Patients were retrospectively identified and categorized by maximum aneurysm diameter and rupture status: small (<60 mm) or large (≥60 mm) and ruptured (rAAA) or nonruptured (non‐rAAA). Three‐dimensional AAA anatomy was digitally reconstructed from computed tomography angiograms for each patient. Finite element analysis was then performed to calculate peak wall stress (PWS) and mean wall stress (MWS) using the patients systolic blood pressure. AAA geometric properties, including normalized ILT thickness (mean ILT thickness/maximum diameter) and % volume (100 × ILT volume/total AAA volume), were also quantified. Results: Patients with small rAAAs had PWS of 123 ± 51 kPa, which was significantly lower than that of patients with large rAAAs (242 ± 130 kPa; P = .04), small non‐rAAAs (204 ± 60 kPa; P < .01), and large non‐rAAAs (270 ± 106 kPa; P < .01). Patients with small rAAAs also had lower MWS (44 ± 14 kPa vs 82 ± 20 kPa; P < .02) compared with patients with large non‐rAAAs. ILT % volume and normalized ILT thickness were greater in small rAAAs (68% ± 11%; 0.16 ± 0.04 mm) compared with small non‐rAAAs (53% ± 16% [P = .02]; 0.11 ± 0.04 mm [P < .01]) and large non‐rAAAs (57% ± 12% [P = .02]; 0.12 ± 0.03 mm [P < .01]). Increased ILT % volume was associated with both decreased MWS and decreased PWS. Conclusions: This study found that although increased ILT is associated with lower MWS and PWS, it is also associated with aneurysm rupture at smaller diameters and lower stress. Therefore, the protective biomechanical advantage that ILT provides by lowering wall stress seems to be outweighed by weakening of the AAA wall, particularly in patients with small rAAAs. This study suggests that high ILT burden may be a surrogate marker of decreased aortic wall strength and a characteristic of high‐risk small aneurysms.