Search

Objective: The Society of Vascular Surgery (SVS) has made it a top priority to implement verification of vascular "centers of excellence". Our institutional aortic network was established in 2008 in order to standardize care of patients with suspected acute aortic pathology. The implementation and success of this program has been previously reported. We sought to use our experience as a benchmark for which to develop prognostic modeling to quantify clinical status upon admission and help predict outcomes. Our objective was to validate the Acute Physiology and Chronic Health Evaluation (APACHE) II scoring system using a cohort of aortic emergencies transferred by an organized transfer network. Method: This was a retrospective, single institution review of patients transferred through an institutional aortic network for acute aortic pathology from 2017-2018. Demographics, comorbidities, aortic diagnosis, APACHE II score, as well as 30-day mortality were recorded. Associations with 30-day mortality were evaluated using two-sample t -tests, ANOVA models, Pearson chi-square tests and Fisher exact tests. Receiver operating characteristic (ROC) curves were fit overall and by pathology to predict 30-day mortality by Apache II total score. Results: There were 395 consecutive transfers were identified. The mean age was 64.7 years. Diagnoses included Type A Dissection (n = 134), Type B (n = 81), Aortic Aneurysm (n = 122), and PAU/IMH (n = 27). Mean APACHE II score on arrival was 12. Overall there were 53 deaths (13.4%) in the cohort. Patients that died had significantly higher Apache II total scores (11.3 vs 16.5, P <.001). The area under the receiver operator characteristic (ROC) curve (AUC) was.66 for the full cohort, indicating a poor clinical prediction test. Conclusion: APACHE II score is a poor predictor of 30-day mortality in a large transfer network accepting all aortic emergencies. The authors believe further refining a prognostic model for diverse population will not only help in predicting outcomes but to objectively quantify illness severity in order to have a basis for comparison among institutions and verification of "centers of excellence". [ABSTRACT FROM AUTHOR]

Background: Significant practice variability exists regarding the management of intermittent claudication (IC) across anatomic segments. We sought to answer the question of whether the safety, efficacy, and durability outcomes of an endovascular approach with or without common femoral endarterectomy for complex aortoiliac occlusive disease (AIOD) justify a surgical approach in patients presenting with IC., Methods: A retrospective single-center review of all patients who were treated using an endovascular approach for AIOD with or without common femoral artery endarterectomy (CFE) from 2010 to 2020 was conducted. The review was limited to those with symptoms of IC. Patient- and limb-level preoperative presentations were reviewed. The outcomes were postoperative complications and patency rates in addition to freedom from re-intervention. Subgroup analyses were conducted to compare patients who underwent endovascular and hybrid procedures., Results: A total of 245 limbs in 180 consecutive patients were analyzed. The mean age was 65 years, and 61% were males. Of 176 patients, 101 (57%) had trans-atlantic inter-society consensus (TASC) class D and 18 (10%) had class C. Eleven limbs (7.4%) had access site complications, 12 (7.9%) had surgical wound complications, and below-the-knee amputation was observed in 2 limbs (0.82%) (2 patients). Two (1.0%) patients had perioperative myocardial infarction (MI), 1 (0.5%) stroke, 1 (0.5%) AKI that progressed to dialysis, and no 30-day mortality. Rutherford's classification was improved during the follow-up period. The 1-, 2-, and 5-year primary patency rates were 94%, 77%, and 58%; primary-assisted patency rates were 98%, 91%, and 79%, respectively; and secondary patency rates were 100% for all follow-up periods. Patients who had concurrent CFE were likely to have hypertension, hyperlipidemia, and anatomically more diffuse disease. No significant differences in patency or reintervention-free survival were observed, though event rates were low in both outcomes and trended toward a protective effect with CFE., Conclusions: Endovascular management for complex AIOD with or without CFE for IC patients is safe, effective, and durable. These results justify an active, patient-centered approach for this advanced anatomic disease pattern. The morbidity of a hybrid approach in the CFE subset is low, and treatment vessel patency is excellent. The presence of anatomically advanced AIOD is not prohibitive for the treatment of patients with IC; however, careful patient selection is essential., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: Spinal cord ischemia (SCI) is a devastating complication that is associated with thoracoabdominal aortic repair, with higher risk associated with increased aortic coverage length, making patients undergoing branched/fenestrated endovascular repair (B/FEVAR) particularly vulnerable. A bundled SCI prevention protocol was previously reported to reduce SCI rates when compared to a historic cohort in a single-center study. Therefore, this analysis aims to further validate and update outcomes associated with the protocol given the routine implementation of this strategy at two institutions (University of Florida and the University of Alabama at Birmingham) since inception., Methods: Components of the SCI prevention protocol include selective cerebrospinal fluid drainage, specified blood pressure parameters, transfusion goals, and selective pharmacologic adjuncts (naloxone, steroids). This protocol was routinely implemented in May 2015. Patients undergoing B/FEVAR from May 2015 to December 2022 constituted the post-protocol cohort (n = 402) and were compared with the pre-protocol cohort (n = 160; January 2010-April 2015). The primary outcome was SCI incidence, and subgroup analysis was conducted among patients deemed to be high-risk (Crawford extent I-III thoracoabdominal aneurysm dissection-related disease, prior aortic repair, coverage proximal to zone 5). Survival analysis was performed using Kaplan-Meier methodology., Results: The pre- and post-protocol cohorts were demographically similar, although more post-protocol patients were American Society of Anesthesiology class IV (86.1% vs 55.0%; P < .001). Thoracoabdominal aneurysm was the most common indication in both groups. Cerebrospinal fluid drain placement was more common in the post-protocol group, particularly among high-risk patients. SCI occurred in 15.9% of pre-protocol patients vs 3.0% of post-protocol patients (P < .001). In high-risk patients, the pre- and post-protocol cohort SCI incidence was 23.2% vs 5.0%, respectively (P < .001). Thirty-day mortality was decreased in the post-protocol cohort (6.3% vs 2.2%; P = .02). Although the post-protocol group had a trend toward improved 1-year survival, this was not statistically significant (84.4% vs 88.3%; log-rank P = .35). Among patients with SCI, 1-year mortality was 28% and 33.3% in the pre- and post-protocol groups, respectively (P = .46)., Conclusions: Implementation of a bundled SCI prevention protocol significantly reduces SCI rates in patients undergoing B/FEVAR, which has now been validated at two institutions, with the most significant reductions occurring among high-risk patients. Although the overall 1-year mortality difference was not significantly different between the cohorts, the high mortality rates among patients with SCI highlights the importance of preventative measures., Competing Interests: Disclosures A.W.B. (all proceeds to the University of Alabama at Birmingham) reports consulting for Artivion, Cook Medical, Medtronic, Philips, and Terumo Aortic; and research support from Cook Medical, Medtronic, Philips, Terumo Aortic, and W.L. Gore & Associates., (Copyright © 2024 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Objective: Hypogastric coverage may be required for occlusive disease at the iliac arterial bifurcation. In this study, we sought to determine patency rates of common-external iliac artery (C-EIA) bare metal stents (BMS) spanning the hypogastric origin in patients with aortoiliac occlusive disease (AIOD). In addition, we sought to identify predictors of C-EIA BMS patency loss and major adverse limb events (MALE) in patients requiring hypogastric coverage. We hypothesized that worsening stenosis of the hypogastric origin would negatively influence C-EIA stent patency and freedom from MALE., Methods: This is a single center, retrospective review of consecutive patients undergoing elective, endovascular treatment of aortoiliac disease (AIOD) between 2010 and 2018. Only patients with C-EIA BMS coverage of a patent IIA origin were included in the study. Hypogastric luminal diameter was determined from preoperative CT angiography. Analysis was performed using Kaplan-Meier survival analysis, univariable and multivariable logistic regression, and receiver operator characteristics (ROC)., Results: There were 236 patients (318 limbs) who were included in the study. AIOD was TASC C/D in 236/318 (74.2%) of cases. C-EIA stent primary patency was 86.5% (95% confidence interval: 81.1, 91.9) at 2 years and 79.7% (72.8, 86.7) at 4 years. Freedom from ipsilateral MALE was 77.0% (71.1, 82.9) at 2 years and 68.7% (61.3, 76.2) at 4 years. Luminal diameter of the hypogastric origin was most strongly associated with loss of C-EIA BMS primary patency in multivariable analysis (hazard ratio: 0.81, p = .02). Insulin-dependent diabetes, Rutherford's class IV or above, and stenosis of the hypogastric origin were significantly predictive of MALE in both univariable and multivariable analyses. In ROC analysis, luminal diameter of the hypogastric origin was superior to chance in prediction of C-EIA primary patency loss and MALE. Hypogastric diameter >4.5 mm had a negative predictive value of 0.94 for C-EIA primary patency loss and 0.83 for MALE., Conclusions: Patency rates of C-EIA BMS are high. Hypogastric luminal diameter is an important and potentially modifiable predictor of C-EIA BMS patency and MALE in patients with AIOD., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objectives: Abdominal Aortic Aneurysms (AAA) in females are less prevalent, have higher expansion rates and experience rupture at smaller diameters than in males. Studies have compared outcomes of the retroperitoneal (RP) and transperitoneal (TP) approach in open aortic aneurysm repair (OAR) with conflicting results. No study to date has compared the two approaches solely in females. In this study we compare midterm outcomes of the RP and TP approach in females undergoing OAR., Methods: Single-center, retrospective review of all females undergoing OAR from 2010 to 2021. Patients undergoing elective, symptomatic and ruptured OAR were included. The cohort was stratified by surgical approach RP versus TP and midterm outcomes were compared amongst the groups. Outcomes included mortality, graft related, and non-graft related complications., Results: A total of 244 patients (RP n = 133; TP n = 111) were identified. Follow-up period was 28 ± 30.7 months. Baseline perioperative characteristics were similar except that more people in the RP group had ejection fraction ((EF) > 50% (82% vs 68%), p = .037). Patients who underwent RP repair had longer visceral/renal ischemia time ( p = .01), larger graft diameter (18 vs 16 mm; p = <0.001), were more likely to have a suprarenal clamp placed(70.5 vs 48.2; p < .001), and had decreased autotransfusion volume (611 vs 861 mL; p < .01) compared to those who underwent TP repair. Number of deaths was higher in the TP group during study follow-up period (36.4 vs 23.8; p = .035), but the difference of the time to event analysis was not significant. There was no difference in all-cause survival at 36 months between RP and TP (77.8 vs 76.8; p = .045). Overall midterm complications were 9.5% in both groups. Any graft related complication was 1.8% in TP versus 3% RP ( p = .69). In a multivariable model, after adjusting for age, urgency, smoking, prior aneurysm repair, and ASA level, the hazard ratio decreases with the RP approach, however this did not reach significance ( p = .052)., Conclusion: In a 12-year period of OAR in females, TP and RP results were comparable at midterm analysis. The RP approach appeared to be used more often for OAR requiring suprarenal clamping. Although the TP group had increased mortality, the difference of the time to event analysis was not significant. Midterm postoperative complications in both groups were low. This suggests that both approaches are safe in the female population and decision should be driven by anatomy and surgeon's preference., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Superior mesenteric artery (SMA) stenting is the preferred approach for patients with symptomatic SMA-associated chronic mesenteric ischemia (CMI). The durability of this modality is impacted by in-stent restenosis (ISR). Duplex ultrasound (DUS) and computed tomographic angiography (CTA)-measured ISR may be weakly correlated and not uniformly associated with recurrence of presenting symptoms. This study aims to analyze the association between the degree of ISR for patients with CMI and to develop a predictive model for symptom recurrence., Methods: Single center, retrospective study included all patients with CMI with SMA stents from the period of 2003 to 2020. Follow-up period analysis included patients' symptoms recurrence, DUS, CTA, and angiography. A receiver operating characteristic (ROC) analysis was used to evaluate whether peak systolic velocity (PSV) was predictive of symptom recurrence. A subgroup analysis of patients (asymptomatic and symptomatic) with SMA ISR was identified; restenosis defined by DUS with peak systolic velocity (PSV) ≥350., Results: The study included 186 patients with the ROC analysis obtained from 503 postoperative visits. PSV was not a predictor of symptoms return with area under the curve (AUC) = 0.49 (95% confidence interval [CI], 0.40-0.57). Agreement analysis between imaging modalities showed higher agreement between CTA and angiogram (AUC, 0.769; 95% CI, 0.688-0.849) vs CTA and DUS (AUC, 0.650; 95% CI, 0.589-0.711). The subgroup analysis of patients with ISR included 99 patients (asymptomatic n = 67; symptomatic n = 32). There was no statistical difference between median time (months) to ISR between both groups: 4.5 (asymptomatic group) and 7.6 (symptomatic group). The use of preoperative antiplatelet (86% vs 65%; P = .015) and P2Y12 receptor blockers (36% vs 13%; P = .016) was more prevalent in the asymptomatic group. There was no difference between the type or number of stents placed, stent diameter, or concomitant celiac artery intervention between both groups., Conclusions: The natural history of SMA and multimodality defined ISR in CMI has not previously been described. Elevated PSV was a poor predictor of symptoms recurrence. Both asymptomatic and symptomatic patients with ISR did not differ in type of stent placed, time to ISR, or involvement of celiac artery. Antiplatelet use pre- and postoperatively appears protective against symptoms recurrence. Our findings underscore the need for long-term surveillance integrating clinical evaluation and multimodality imaging when indicated., Competing Interests: Disclosures None., (Copyright © 2023 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Complex open abdominal aortic aneurysm (AAA) repair often necessitates revascularization of renal arteries by either renal artery reimplantation or bypass. This study aims to evaluate the perioperative and short term outcomes between these 2 strategies of renal artery revascularization., Methods: We performed a retrospective review of patients who underwent open AAA repair from 2004 to 2020 at our own institution. Patients who underwent elective suprarenal, juxtarenal, or type 4 thoracoabdominal aneurysm repair were identified using current procedural terminology (CPT) codes and a retrospectively maintained database of AAA patients. Patients who had symptomatic aneurysm or significant renal artery stenosis before AAA repair were excluded. Patient demographics, intraoperative conditions, renal function, bypass patency, and perioperative and postoperative outcomes at 30 days and 1 year were compared., Results: One hundred and forty-three patients underwent either renal artery reimplantation (n = 86) or bypass (n = 57) during this time period. The mean age was 69.7 years and 76.2% of the patients were male. Median preoperative creatinine was 1.2 mg/dL for the renal bypass group versus 1.06 mg/dL for reimplantation (P = 0.088). Both groups had similar median preoperative glomerular filtration rate (GFR) of >60 mL/min (P = 0.13). Bypass and reimplantation groups had similar perioperative complications including acute kidney injury (51.8% vs. 49.4% P = 0.78), inpatient dialysis (3.6% vs. 1.2% P = 0.56), myocardial infarction (1.8% vs. 2.4% P = 0.99), and death (3.5% vs. 4.7% P = 0.99), respectively. During the 30-day follow-up period, renal artery stenosis was identified in 9.8% of bypasses and 6.7% of reimplantations (P = 0.71). Six point one percent of patients in the bypass group had renal failure requiring dialysis (both acute and permanent) compared to 1.3% in reimplantation group (P = 0.3). For those who had 1-year follow-up, the reimplantation group had higher new incidence of renal artery stenosis compared to bypass group (6 vs. 0 P = 0.16)., Conclusions: Given that there is no significant difference in outcomes between renal artery reimplantation and bypass within 30 days or at 1-year follow-up, both bypass and reimplantation are acceptable means for renal artery revascularization during elective AAA repair., (Copyright © 2023. Published by Elsevier Inc.)

Background: Acute type B aortic dissections (TBADs) can become complicated at any time point, necessitating surgical repair. We sought to investigate the effect of interhospital transfer on the development of delayed complications in acute type B aortic dissection (dcTBAD)., Methods: All patients who presented with acute TBAD to a tertiary aortic center from 2015 to 2019 were analyzed. Patients were divided into initially complicated type B aortic dissection (icTBAD) (0-24 hours from symptom onset), dcTBAD (25 hours to 14 days), and uncomplicated type B aortic dissection (ucTBAD) groups. Criteria for complicated dissection were aortic rupture, malperfusion, or rapid aortic growth. Demographics, patient history, the timing of presentation, imaging findings, and clinical outcomes were compared between groups., Results: Of 120 acute TBADs included, 27 (22%) were initially complicated (aortic rupture, n = 9; malperfusion, n = 18). Twenty-one (18%) developed delayed complications (aortic rupture, n = 3; malperfusion, n = 14; rapid growth, n = 4) at a median of 7.0 [4.0, 9.0] days from symptom onset. Seventy-two (60%) remained uncomplicated. Overall, 111 (93%) presented as transfers from outside hospitals (icTBAD, n = 25; dcTBAD, n = 21; ucTBAD, n = 65). Of those, dcTBADs were more likely to have a prolonged delay between presentation to the outside hospital and referral to the tertiary center compared to ucTBADs (median = 1.00 [0.0, 5.0] days delayed vs. 0.00 [0.0, 0.0] days delayed; P < 0.001). Initially uncomplicated patients referred for transfer ≥24 hours from presentation went on to develop dcTBAD more often than those transferred in <24 hours (73% vs 13%; P < 0.001). Of dcTBADs, 38% had no high-risk features on initial imaging. Patients with dcTBAD had significantly longer length of stay (median = 12 vs 7 days; P = 0.006). In-hospital mortality was significantly higher in dcTBADs than ucTBADs (9.5% vs 0%; P = 0.047). In-hospital mortality was not significantly different between dcTBADs and icTBADs (9.5% vs. 11%; P > 0.05)., Conclusions: The incidence and consequence of dcTBADsare not insignificant. Late referral and transfer to a tertiary aortic center (≥24 hours from initial presentation) was associated with dcTBADsrequiring surgical intervention. The development of dcTBADwas associated with increased length of stay and increased in-hospital mortality., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Given the ongoing nature of research in the social determinants space and urges to improve United States Preventive Services Task Force screening efforts for abdominal aortic aneurysms (AAAs), this project aims to characterize the association between the level of socioeconomic deprivation, rurality, and ruptured AAA (rAAA) presentation across the United States., Methods: We queried the Vascular Quality Initiative registry (2010-2019) for patients with AAAs. The area deprivation index (ADI) is an index from 1 to 100 used to capture socioeconomic status. ADI was grouped into quintiles, with the most deprived regions being quintile 5 and having the highest ADI index. Multivariable logistic regression assessed the association between ADI, rurality, and rAAA presentation overall and before age 65., Results: Of the 82,909 patients included, 11,458 patients (14%) resided in the most socioeconomically deprived regions, and 18,083 patients (22%) lived in rural regions. Overall, 6831 patients (8.2%) experienced an rAAA, with 4696 patients (69%) residing in the three most deprived quintiles. Most patients underwent endovascular repair (n = 67,933; 82%), followed by open repair (n = 14,976; 18%). On multivariable analysis, residence in the most socioeconomically deprived region was associated with a near 1.5-fold increased odds of presenting with an rAAA compared with a residence in the least deprived regions (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.31-1.63; P < .001), whereas urban residence was associated with a decreased odds to present with an rAAA compared with rural residence (OR, 0.84; 95% CI, 0.79-0.89; P < .001). When stratifying the study population by the United States Preventive Services Task Force recommended age for AAA screening (65 years old), 14,147 patients (17%) were under 65. Of those under 65, 1381 patients (9.8%) experienced a rAAA, and 9955 patients (71%) resided in the three most deprived quintiles. Residence in the most socioeconomically deprived region was associated with an increased odds of presenting with an rAAA compared with residence in the least deprived region (OR, 1.31; 95% CI, 1.01-1.69; P = .042). However, there were no significant associations between rural residence and increased rAAA presentation among individuals under 65 (OR, 1.07; 95% CI, 0.93-1.23; P = .36)., Conclusions: Among all patients in this study, patients residing in highly socioeconomically deprived or rural regions were more likely to present with an rAAA, but among those under 65, only residence in a socioeconomically deprived area was associated with increased odds of rAAA presentation. Understanding the effects of socioeconomic deprivation on rAAA presentation can identify at-risk populations for early AAA screening before rupture., Competing Interests: Disclosures None., (Copyright © 2023 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Endovascular intervention (EI) is the most commonly used modality for chronic mesenteric ischemia (CMI). Since the inception of this technique, numerous publications have reported the associated clinical outcomes. However, no publication has reported the comparative outcomes over a period of time in which both the stent platform and adjunctive medical therapy have evolved. This study aims to assess the impact of the concomitant evolution of both the endovascular approach and optimal guideline-directed medical therapy (GDMT) on CMI outcomes over three consecutive time eras., Methods: A retrospective review at a quaternary center from January 2003 to August 2020 was performed to identify patients who underwent EIs for CMI. The patients were divided into three groups based on the date of intervention: early (2003-2009), mid (2010-2014), and late (2015-2020). At least one angioplasty/stent was performed for the superior mesenteric artery (SMA) and/or celiac artery. The patients' short- and mid-term outcomes were compared between the groups. Univariable and multivariable Cox proportional hazard models were also conducted to evaluate the clinical predictors for primary patency loss in SMA only subgroup., Results: A total of 278 patients were included (early, 74; mid, 95; late, 109). The overall mean age was 71 years, and 70% were females. High technical success (early, 98.6%; mid, 100%; late, 100%; P = .27) and immediate resolution of symptoms (early, 86.3%; mid, 93.7%; late, 90.8%; P = .27) were noted over the three eras. In both the celiac artery and SMA cohorts, the use of bare metal stents (BMS) declined over time (early, 99.0%; mid, 90.3%; late, 65.5%; P < .001) with a proportionate increase in covered stents (CS) (early, 0.99%; mid, 9.7%; late, 28.9%; P < .001). The use of postoperative antiplatelet and statins has increased over time (early, 89.2%; mid, 97.9%; late, 99.1%; P = .003) and (early, 47%; mid, 68%; late, 81%; P = .001), respectively. In the SMA stent-only cohort, no significant differences were noted in primary patency rates between BMS and CS (hazard ratio, 0.95; 95% confidence interval, 0.26-2.87; P = .94). High-intensity preoperative statins were associated with fewer primary patency loss events compared to none/low- or moderate-intensity statins (hazard ratio, 0.30; 95% confidence interval, 0.11-0.72; P = .014)., Conclusions: Consistent outcomes were observed for CMI EIs across three consecutive eras. In the SMA stent-only cohort, no statistically significant difference in early primary patency was noted for CS and BMS, making the use of CS at additional cost controversial and possibly not cost effective. Notably, the preoperative high-intensity statins were associated with improved SMA primary patency. These findings demonstrate the importance of guideline-directed medical therapy as an essential adjunct to EI in the treatment of CMI., (Copyright © 2023 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Cardiovascular complications are a major cause of morbidity and mortality in the postoperative period after major vascular surgery. Depending on the study population, up to 25% of patients have troponin elevation after noncardiac surgery, yet many do not meet the diagnosis of myocardial infarction (MI). Although outcomes of routine troponin elevation in patients undergoing mixed major vascular surgery have been evaluated, this has not been studied exclusively in elective, open abdominal aortic aneurysm repair (oAAA), especially regarding perioperative and overall mortality., Methods: We conducted a single-center, retrospective review of routine troponin surveillance for consecutive, oAAA from 2014 to 2019. A total of 319 patients were identified and analyzed for management patterns and interventions. The cohort was stratified into groups for comparison based on those in whom troponin was routinely checked (RC) as part of a care strategy during the study period, not routinely checked (NRC), elevated troponin (ET) >0.001 ng/mL, and not elevated. The median follow-up was 21.5 ± 23.8 months. Groups were compared on demographic data, cardiac comorbidities, 30-day and 3-year outcomes for MI and death using two-sample t-tests, Wilcoxon rank sum tests, Pearson chi-square tests, and Fisher exact tests when appropriate., Results: Troponin was measured in 83.7% (267/319) of patients who underwent elective oAAA repair. Routine troponin checks were obtained in 79.9% (255/319) of patients. ET was identified in 16.5% of those with RC (42/255) and 4.7% of those with NRC (3/64). Of patients with ET, 37.8% (17/45) had a cardiology consultation, 4.4% (2/45) had a percutaneous coronary intervention (PCI), and 4.4% (2/45) had another cardiac intervention. All 4 patients undergoing PCI or other cardiac intervention had received routine troponin checks. Patients with ET were older (71.2 vs. 68.6; P = 0.04), more likely to receive intraoperative blood products (P = 0.003), had longer operative times (P = 0.011), higher length of stay (9 vs. 7 days; P < 0.01), and higher 30-day MI rate (3 vs. 0; P = 0.04). They had neither longer aortic clamp times nor worse preoperative cardiac function, and the proximal clamp position during oAAA repair did not impact troponin detection. Additionally, 3-year overall mortality was increased in patients who had ET but there was not a significant difference in 3-year mortality between groups receiving routine troponin checks versus not., Conclusions: ET, identified after elective oAAA repair, was associated with a higher risk of 30-day MI and lower overall survival. However, it was not demonstrated that routine assessment of troponin levels postoperatively leads to decreased 3-year mortality in this setting., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Aneurysmal pathology of the aorta is well-defined in the Marfan syndrome (MFS) population. Owing in part to the rarity of pathologies, the prevalence of intracranial aneurysms (IA) in MFS is poorly defined. There is debate as to whether or not there is an association between the two. The aim of this study was to evaluate the prevalence of IA in a population of patients with MFS who underwent intracranial imaging., Methods: This was a single-center retrospective review of patients with MFS. Between 1995 and 2021, 983 patients were reviewed. We identified 198 patients with MFS who had intracranial imaging. Imaging consisted of CTA and/or MRA, and was read by an attending radiologist. Details of the aneurysm, patient demographics, and aortic characteristics were collected., Results: The prevalence of IA was 7.1% (14/198). Age of patients with IA (55.0 ± 15.1 years) was not significantly different than those without IA (52.6 ± 16.0 years) (P = .58). The most common location of IA was the internal carotid artery. The mean diameter of the IA was 7 ± 5.8 mm. No ruptures of the internal carotid artery were identified. One patient (0.5%) underwent intervention for the IA. There were no significant differences found in aortic characteristic including dimensions, history of dissection, or aneurysm., Conclusions: In a large, single-center experience over 20 years, we identified patients with confirmed MFS who underwent intracranial imaging. The prevalence of IA in our experience was 7.1%. There were no patient or aortic characteristics found to be significantly associated with IA; however, this finding may be due to the small number of aneurysms. Although this number is higher than the historically reported prevalence in the general population, a collection of experiences from multiple institutions will likely be required to truly define the risk of IA in MFS and to determine whether screening is warranted., (Copyright © 2023 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Strategies for embolization of type 2 endoleaks include translumbar, transgraft, transarterial, and transcaval approaches. The transcaval approach is limited by an inconsistent ability to access the aortic sac and the risk of puncturing and damaging the endograft or adjacent structures. We describe a novel technique for caval to aortic aneurysm sac access and report early outcomes., Methods: A retrospective review of all patients who underwent transcaval embolization (TCE) at a tertiary referral center. From March 2019 to June 2021, 12 patients were identified to have undergone a novel approach to transcaval aortic sac access using a 0.014″ heavy weight tip wire guide and continuous current electrocautery to create the connection between the inferior vena cava and aortic aneurysm sac. The endoleak outflow vessel is then selectively embolized with coils or liquid embolic agents. When selective embolization was not possible, the aneurysm sac was instilled with liquid embolic agents to induce thrombosis., Results: Twelve patients underwent transcaval embolization using this method over the 3-year period. The average patient age was 79.2 ± 6.2 years and 10/12 (83.3%) were male. A high rate of comorbidities was noted in the cohort. Transcaval access into the aortic sac was achieved in all patients, while selective cannulation of outflow vessels was accomplished in 2/12 (16%) target vessels. Of these, both cases had vessels embolized using detachable coils and liquid embolic agents. Nonselective embolization was performed using liquid embolic and thrombotic agents in the other 10/12 cases. There was one perioperative complication of minor bleeding (1/12, 8.3%). Two patients were observed in intensive care unit for back pain. A persistent endoleak was identified on postoperative imaging performed at 30 days in 4/12 (33.3%) patients. Sac enlargement > 5 mm following TCE was observed in 3/12 (25%) patients. Three patients underwent open conversion with endovascular aneurysm repair explant. One patient was explanted at 1 month after failure to embolize the endoleak flow channel using TCE. A second was explanted for persistent endoleak found to be a Type IIIb with aortic diameter growth > 5 mm at 15-month follow-up. The third explant was performed for aortic sac infection at 4 months postprocedure without endoleak., Conclusions: TCE is an adjunctive technique to treat endoleaks in patients who have either failed transarterial or translumbar access. An electrified 0.014″ chronic total occlusion wire technique for transcaval access to the aortic sac for endoleak embolization can be successful in all cases without significant acute morbidity or mortality. The transcaval approach is still limited by ability to steer catheters and microcatheters into the outflow vessels with a resultant persistent endoleak and eventual need for explant., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: The natural history of isolated common iliac artery aneurysms (CIAAs) has not been well-studied. The optimal size threshold for elective repair of isolated CIAAs is also not well-defined. We sought to determine the natural history and growth rates of isolated CIAAs to justify a surveillance protocol and size for elective repair., Methods: Isolated CIAAs (>2 cm) identified from January 1, 2008, through February 29, 2020, at a single center were reviewed. Patient demographics, comorbidities, and details of CIAA operative repairs were retrospectively collected. All available duplex ultrasound and computed tomography scans were reviewed from time of CIAA identification through June 2020., Results: There were 244 isolated CIAAs found in 167 patients. The cohort was 94% male with an average age of 68.1 ± 8.8 years at the time of CIAA detection. CIAAs were identified with ultrasound examination 69% of the time with a mean CIAA diameter of 2.3 cm. Operative repair of a CIAA was performed in 11.4% of the cohort at an average diameter of 3.30 ± 1.02 cm. The majority of these repairs were performed via an endovascular approach (73.7%; n = 14). There were no symptomatic or ruptured isolated CIAAs. Concurrent aortic growth that led to an abdominal aortic aneurysm with diameter of at least 3 cm occurred in 10.6% (n = 26) of isolated CIAAs. The average length of time from CIAA diagnosis to repair was 65.7 ± 47.1 months. The overall CIAA growth rate was 0.4 mm/y. A subgroup analysis based on CIAA size demonstrated a growth rate of 0.2 mm/y fore CIAAs 2.00 to 2.49 cm, 0.3 mm/y for CIAAs 2.50 to 2.99cm, and 1.3 mm/y for CIAAs 3.0 cm or larger. There were two CIAAs greater than 3.0 cm with extreme growth, which significantly impacted the CIAA growth rate on sensitivity analysis. After excluding those two CIAAs from the model, the overall CIAA growth rate was 0.3 mm/y. The subgroup analysis then demonstrated a growth rate of 0.2 mm/y for CIAAs 2.00 to 2.49cm, 0.3 mm/y for CIAAs 2.50 to 2.99cm, and 0.5 mm/y for CIAAs 3 cm or larger., Conclusions: Isolated CIAAs are typically slow growing aneurysms that expectedly grow faster as they enlarge. Given the rare occurrence of rapid isolated CIAA growth, we recommend surveillance at 3 years for 2.00 to 2.49 cm isolated CIAAs, 2 years for 2.50 to 2.99 cm isolated CIAAs, and yearly for isolated CIAAs greater than 3.0 cm. The lack of symptomatic or ruptured isolated CIAAs in this study supports delaying elective repair until an isolated CIAA diameter reaches at least 3.5 cm. These recommendations should be considered for isolated CIAA practice guidelines., (Copyright © 2022 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Small abdominal aortic aneurysms (AAA) surveillance intervals remain controversial and difficult to standardize. Current Society for Vascular Surgery guidelines lack quality evidence. The objective of this study is to examine patients followed in a high volume non-invasive vascular laboratory, determine if the current guidelines are fitting in clinical practice, and attempt to further identify risk factors for accelerated aneurysm growth., Methods: A retrospective analysis of patients who underwent at least two ultrasounds for AAA in the vascular laboratory during 2008 -2018 with baseline diameter less than 5.0 cm was conducted. Patient demographics were collected. Groups were then created for comparison using the size criteria according to SVS guidelines. In addition, we compared overall growth rates specifically evaluating rapid growth (rate of at least 1.0 cm/year and size change of at least 0.5 cm from previous imaging), expected growth (any growth below 1.0 cm/year and of at least 0.5 cm from baseline) and no growth., Results: A total of 1581 patients (1232 male and 349 female) were identified with a total of 5945 ultrasound studies. The median age was 73 years and mean follow-up was 27.8 months. Baseline AAA size was 3.0 -3.9 cm in 986 patients and 4.0 -4.9 cm in 595 patients. The average maximum growth rate was 0.18 cm/year for AAAs 3.0 -3.9 cm and 0.36 cm/year for AAAs 4.0 -4.9 cm (P <0.001). Patients with AAA 4.0 -4.9 cm at baseline were more likely to be white, male, hypertensive and have chronic kidney disease (P <0.05). 1078 patients (68.2%) demonstrated no growth over the observed time period with 342 patients (21.6%) demonstrating expected growth and 161 (10.2%) rapid growth. Male gender and baseline AAA size of 4.0 -4.9 cm were more likely to demonstrate rapid growth (P = 0.002) and eventual repair (P <0.001). Metformin use was more common in the AAA group with no growth (P <0.05). Freedom from rapid growth and repair indication at 2 years was significantly lower in those patients with baseline aneurysms 3.0 -3.9 cm (P <0.001)., Conclusion: The overall low rate of events in small AAAs supports continued surveillance every 3 years for AAAs 3.0-3.9 cm and yearly for male patients with AAAs 4.0 -4.9 cm as recommended by the SVS Guidelines. Female gender may have less rapid growth than previously reported but likely merit more rigorous surveillance particularly as the AAAs approach 5.0 cm. Metformin use continues to demonstrate it may abrogate aneurysmal growth. Lastly, there is a subset of patients that exhibit more rapid growth of their small AAAs, and further study will be required to classify these patients., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: There is no consensus on the method of obtaining abdominal aortic aneurysm (AAA) maximum diameters based on computed tomographic angiography, and the reproducibility and accuracy of different methods have recently been debated due to advancements in imaging. This study compared the two most common methods based on orthogonal planes and centerline of flow to determine the discordances and accuracy amongst experiences readers., Methods: The computed tomographic angiography max diameters of 148 AAAs were measured by three experienced observers, including a vascular surgeon, a radiologist and an imaging cardiologist. Observers used two different methods with standardized protocols: multiplanar reformations based on orthogonal planes, and a software using 3D aortic reconstructions to create centerline flow lumen providing diameters based on cross sections perpendicular to this lumen. Agreements and reliability of measurement methods were assessed by intra-class correlation coefficient and Bland - Altman analysis. Discordances between measurements of the methods and the original reported measurement, as well as outside hospitals were compared., Results: The average age of the cohort was 75 years and aortic diameters ranged from 3.8 to 9.6 cm. For orthogonal readings, there were agreements within 3 mm between 86% and 92% of the time, while centerline - reading agreement was between 88% and 94%, which was not statistically significant. The intra-class correlation coefficient was high between method type and between readers. Within methods, agreement was between 0.96 and 0.97, while within - reader agreement measures was between 0.96 and 0.98. In comparison to the original and the outside hospital reports, 10% ≥ of the original and 20% ≥ of the outside hospital reported measurements were discordant between the readers., Conclusion: Maximal AAA measurements can have substantial variability leading to clinical significance and change in patient management and outcomes. Based on the results, orthogonal and centerline measurement methods have equally high agreements and concordance within 3 mm and low variations at a high volume center. However, when compared to the official read reports, there is high discordance rates that can significantly alter patient outcomes. A standardized method of measurement maximum diameter can reduce variations and discordances among different methods., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: Accurate documentation of patient care and acuity is essential to determine appropriate reimbursement as well as accuracy of key publicly reported quality metrics. We sought to investigate the impact of standardized note templates by inpatient advanced practice providers (APPs) on evaluation and management (E/M) charge capture, including outside of the global surgical package (GSP), and quality metrics including case mix index (CMI) and mortality index (MI). We hypothesized this clinical documentation initiative as well as improved coding of E/M services would result in increased reimbursement and quality metrics., Methods: A documentation and coding initiative on the heart and vascular service line was initiated in 2016 with focus on improving inpatient E/M capture by APPs outside the GSP. Comprehensive training sessions and standardized documentation templates were created and implemented in the electronic medical record. Subsequent hospital care E/M (current procedural terminology codes 99231, 99232, 99233) from the years 2015 to 2017 were audited and analyzed for charge capture rates, collections, work relative value units (wRVUs), and billing complexity. Data were compared over time by standardizing CMS values and reimbursement rates. In addition, overall CMI and MI were calculated each year., Results: One year following the documentation initiative, E/M charges on the vascular surgery service line increased by 78.5% with a corresponding increase in APP charges from 0.4% of billable E/M services to 70.4% when compared with pre-initiative data. The charge capture of E/M services among all inpatients rose from 21.4% to 37.9%. Additionally, reimbursement from CMS increased by 65% as total work relative value units generated from E/M services rose by 78.4% (797 to 1422). The MI decreased over the study period by 25.4%. Additionally, there was a corresponding 5.6% increase in the cohort CMI. Distribution of E/M encounter charges did not vary significantly. Meanwhile, the prevalence of 14 clinical comorbidities in our cohort as well as length of stay (P = .88) remained non-statistically different throughout the study period., Conclusions: Accurate clinical documentation of E/M care and ultimately inpatient acuity is critical in determining quality metrics that serve as important measures of overall hospital quality for CMS value-based payments and rankings. A system-based documentation initiative and expanded role of inpatient APPs on vascular surgery teams significantly improved charge capture and reimbursement outside the GSP as well as CMI and MI in a consistently complex patient population., (Published by Elsevier Inc.)

Objective/background: Spinal drain (SD) placement is an adjunct used in open and endovascular aortic surgery to mitigate the risk of spinal cord injury. SD placement can lead to subdural hematoma and intracranial hemorrhage (SDH/ICH). Previous studies have highlighted a correlation between incidence of SDH/ICH and amount of cerebrospinal fluid (CSF) drained. We have two philosophies of SD management in our institution. One protocol allows fluid removal for pressure >10 cm H 2 O with no volume restriction. A second, similar protocol restricts CSF drainage to <25 mL/h. We examined SD complications and the influence of volume restriction., Methods: Patients were identified according to the Current Procedure Terminology codes for SD placement, thoracic endovascular aortic repair, fenestrated/branched endovascular aortic repair, endovascular abdominal aortic repair, and open thoracic or thoracoabdominal aortic repair between January 1, 2012, and December 31, 2015. Patients' demographics included age, gender, race, body mass index, and comorbidities such as hypertension, chronic obstructive pulmonary disease, stroke, transient ischemic attack, diabetes mellitus, bleeding disorder, and connective tissue disorders. Management protocol was classified as volume independent (VI) or volume dependent (VD) by physician order. Postoperative complications related to the SD were noted., Results: We identified 948 patients who had an SD placed during the study period; 473 were done before aortic surgeries. A total of 364 patients (77%) underwent endovascular aortic surgery. The mean age at the time of procedure was 67.2 years, and 66% of patients were male. Thirty-nine patients (8.3%) were noted to have connective tissue disorders. Bloody SD placement occurred in 14 patients (3.1%) requiring rescheduling of the operation. SDH/ICH occurred in 11 patients (2.3%), postoperative blood tinged SD output in 94 patients (19.9 %), and 22 patients (4.7 %) had a CSF leak after SD removal. The incidence of SDH/ICH was not affected by the management protocol (2.6% VI vs 2.0% VD, P = .66), whereas the incidence of postoperative blood tinged SD output was significantly higher in the VI group (25.1% VI vs 15.0% VD, P = .006). Perioperative low-dose aspirin (81 mg) and prophylactic subcutaneous heparin did not increase the incidence of SDH/ICH. Postoperative thrombocytopenia was found to be associated with higher incidence of SDH/ICH (median 86,000 vs 113,000, P = .002)., Conclusions: Severe complications of SD placement (SDH/ICH) occur in 2.3% of SD patients undergoing aortic surgery, and the risk is higher in the setting of postoperative thrombocytopenia. SD volume limitation, blood tinged drainage, antiplatelet medication, and low-dose heparin do not affect the risk of SDH/ICH. The risks of spinal drains for aortic surgery should be balanced against potential benefits., (Copyright © 2021 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Objective: Central venous stenosis is one of the most challenging complications in patients requiring hemodialysis. Venous thoracic outlet syndrome is an underappreciated cause of central venous stenosis in patients requiring dialysis that can result in failed percutaneous intervention and loss of a functioning dialysis access. Limited data exist about the safety and outcomes of first rib resection in patients requiring hemodialysis, and the results have been confounded by the various surgical approaches used. The purpose of the present study was to evaluate the safety, operative outcomes, and patency of the existing dialysis access after transaxillary thoracic outlet decompression., Methods: A retrospective medical record review was performed from January 2008 to December 2019 of patients who had undergone thoracic outlet decompression for subclavian vein stenosis with ipsilateral upper extremity hemodialysis access. The baseline characteristics and comorbidities were reviewed. The operative and postoperative course were evaluated. The survival and patency rates were analyzed using the life-table method and Kaplan-Meier curve., Results: A total of 18 extremities in 18 patients were identified. Their mean age was 59 ± 11 years, and 89% were men. A total of 13 fistulas and 5 grafts were included. All patients had undergone repair via a transaxillary approach. First rib resection, anterior scalenectomy, and circumferential venolysis were performed in all 18 patients. The mean operative time was 99 ± 19 minutes, with an estimated blood loss of 78 ± 66 mL. The median length of stay was 2 days. No patient had died at 30 days. The survival rate at 1 year was 83%. The primary, primary-assisted, and secondary patency at 1 year were 42%, 69%, and 93%, respectively., Conclusions: Thoracic outlet decompression via the transaxillary approach is a technically feasible and safe operation in patients with ipsilateral upper extremity hemodialysis access. Patients with threatened dialysis access due to subclavian vein stenosis should be carefully evaluated for possible extrinsic compression at the costoclavicular junction. These patients might benefit from transaxillary first rib resection, scalenectomy, and venolysis., (Copyright © 2021 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Objective: Carotid endarterectomy (CEA) is a proven intervention for stroke risk reduction in symptomatic and asymptomatic patients. High-risk patients are often offered carotid stenting to minimize the risk and optimize the outcomes. As a referral center for high-risk patients, we evaluated and analyzed our experience with high-risk CEA patients., Methods: We retrospectively reviewed consecutive patients who had undergone CEA at a tertiary referral center. The demographics, indications for surgery, physiologic and anatomic risk factors, intraoperative surgical management, perioperative complications, morbidity, and mortality were analyzed. The high-risk physiologic factors identified included an ejection fraction <30%, positive preoperative stress test results, and compromised pulmonary function test results. The high-risk patients included those requiring home oxygen, those with a partial pressure of oxygen of <60 mm Hg, and patients with a forced expiratory volume in 1 second of <30%. The high-risk anatomic factors identified included previous head and/or neck radiation, a history of ipsilateral neck surgery, contralateral nerve palsy, redo CEA, previous ipsilateral stenting, contralateral occlusion, contralateral CEA, nasotracheal intubation, and digastric muscle division. After propensity score matching, patients with and without high-risk physiologic and anatomic factors were compared. The primary outcomes were a composite of stroke, myocardial infarction, and 30-day mortality. The secondary outcomes were cranial injury and surgical site infection., Results: During a 10-year period, 1347 patients had undergone CEA at the Cleveland Clinic main campus. Of the 1347 patients, 1152 met the criteria for analysis. Propensity score matching found adequate matches for 424 high-risk patients, with 173 patients having at least one physiologic high-risk factor and 293 at least one anatomic high-risk factor. No significant differences were found in the primary composite outcome or any of its components. Overall, the stroke rate for the standard-risk and high-risk patients was 1.9% and 1.4%, respectively. The high-risk patients were significantly more likely to have experienced a cranial nerve injury, although most were temporary. When patients with one or multiple risk factors were analyzed, no significant difference was found in the primary composite outcome or any of its components. Patients with two or more risk factors were significantly more likely to have experienced a cranial nerve injury, with most being temporary., Conclusions: In our large series, CEA remained a viable and safe surgical solution for patients with high-risk anatomic and physiologic risk factors, with acceptable stroke, myocardial infarction, and 30-day mortality rates., (Copyright © 2020 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Objective: Iliac conduits (ICs) are used for challenging iliac access during endovascular aortic aneurysm repair (EVAR) with contradictory reports of safety and increased surgical complications, morbidity, and mortality in national database reviews. The objective of this study was to examine outcomes related to IC placement before or concomitant with EVAR at a high-volume single center., Methods: A retrospective analysis of patients who underwent IC placement for endovascular aortic repair from 2006 to 2016 was conducted. Planned and unplanned, as well as staged and concomitant IC for EVAR, thoracic EVAR, and fenestrated/branched EVAR were included. Categorical factors were described using frequencies and percentages. Continuous measures were summarized in comparative tables. Comparisons between the planned and unplanned groups, concomitant and staged groups, and between those with and without a postoperative event were performed using Pearson χ 2 tests, two-sample t-tests, and Wilcoxon rank-sum tests., Results: A total of 137 patients underwent IC placement, of which 9 were bilateral procedures, for a total of 144 IC placements. IC placement was necessary in 14 EVARs (9.7%), 38 thoracic EVARs (26.4%), and 92 fenestrated/branched EVARs (63.9%). The 30-day related mortality was 2.1% (n = 3). Perioperative morbidities included return to the operating room in five patients (5.6%) for bleeding (n = 4) and graft thrombosis (n = 1), 4 myocardial infarctions (2.8%), 5 episodes of respiratory failure (3.5%), 12 wound complications (8.3%), and 7 renal injuries (4.9%), of which 3 had progression to dialysis (2.1%). Other complications included return to the operating room for endoleak reintervention (n = 3) and late graft infection (n = 1 [0.7%]). There were 112 ICs (77.8%) planned and 65 (45.1%) were staged. Staged ICs were less likely to have postoperative complications (P < .001), respiratory failure (P < .05), infectious complications (P < .05), and postoperative cerebrovascular accidents (P < .05). ICs were done to accommodate 20F to 24F sheath sizes in 131 instances (91.0%). Factors associated with unplanned IC placement were iliac rupture and an inability to advance the endograft in arteries deemed size-appropriate preoperatively (P < .001). Unplanned ICs were associated with higher estimated blood loss (P < .001), operating room transfusion volume (P < .001), and overall complication rates (P < .05). Women (P < .05), preoperative chronic kidney disease (P < .05), and concomitant IC placement (P < .001) were associated with higher overall complication rates. Operative time, estimated blood loss, and operating room transfusion volume were associated with increased rate of complications in comparison between all subgroups (P < .05)., Conclusions: ICs are a safe and viable option for high-risk patients with challenging iliac artery access for EVVAR. ICs are best performed in a planned fashion or in a staged manner, when feasible., (Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

With the increasing incidence of end-stage renal disease, hemodialysis vascular access presents an ongoing struggle, and a multidisciplinary approach must be considered to provide long-term durable access for patients on chronic hemodialysis. Surgeons must be very thoughtful in planning the steps of access for these patients and consider fistula first and catheter last, without forgetting that prosthetic grafts may be a legitimate first option for patients. This article provides a review of surgical management of dialysis access, including primary access options and follow-up of this difficult patient population.

The S. cerevisiae genome encodes two M16A enzymes: Axl1p and Ste23p. Of the two, Ste23p shares significantly higher sequence identity with M16A enzymes from other species, including mammalian insulin-degrading enzymes (IDEs). In this study, recombinant Ste23p and R. norvegicus IDE (RnIDE) were isolated from E. coli, and their enzymatic properties compared. Ste23p was found to cleave established RnIDE substrates, including the amyloid-beta peptide (Abeta1-40) and insulin B-chain. A novel internally quenched fluorogenic substrate (Abz-SEKKDNYIIKGV-nitroY-OH) based on the polypeptide sequence of the yeast P2 a-factor mating propheromone was determined to be a suitable substrate for both Ste23p and RnIDE, and was used to conduct comparative enzymological studies. Both enzymes were most active at 37 degrees C, in alkaline buffers and in high salt environments. In addition, the proteolytic activities of both enzymes towards the fluorogenic substrate were inhibited by metal chelators, thiol modifiers, inhibitors of cysteine protease activity and insulin. Characteristics of STE23 expression were also evaluated. Our analysis indicates that the 5' terminus of the STE23 gene has been mischaracterized, with the physiologically relevant initiator corresponding to residue M53 of the publicly annotated protein sequence. Finally, we demonstrate that, unlike haploid-specific Axl1p, Ste23p is expressed in both haploid and diploid cell types. Our study presents the first comprehensive biochemical analysis of a yeast M16A enzyme, and provides evidence that S. cerevisiae Ste23p has enzymatic properties that are highly consistent with mammalian IDEs and other M16A enzymes., (Copyright (c) 2009 John Wiley & Sons, Ltd.)