Predictors of perioperative morbidity and mortality in open abdominal aortic aneurysm repair

Effect of Hydralazine on Angiotensin II-Induced Abdominal Aortic Aneurysm in Apolipoprotein E-Deficient Mice

The rupture of an abdominal aortic aneurysm (AAA) causes about 200,000 deaths worldwide each year. However, there are currently no effective drug therapies to prevent AAA formation or, when present, to decrease progression and rupture, highlighting an urgent need for more research in this field. Increased vascular inflammation and enhanced apoptosis of vascular smooth muscle cells (VSMCs) are implicated in AAA formation. Here, we investigated whether hydralazine, which has anti-inflammatory and anti-apoptotic properties, inhibited AAA formation and pathological hallmarks. In cultured VSMCs, hydralazine (100 μM) inhibited the increase in inflammatory gene expression and apoptosis induced by acrolein and hydrogen peroxide, two oxidants that may play a role in AAA pathogenesis. The anti-apoptotic effect of hydralazine was associated with a decrease in caspase 8 gene expression. In a mouse model of AAA induced by subcutaneous angiotensin II infusion (1 µg/kg body weight/min) for 28 days in apolipoprotein E-deficient mice, hydralazine treatment (24 mg/kg/day) significantly decreased AAA incidence from 80% to 20% and suprarenal aortic diameter by 32% from 2.26 mm to 1.53 mm. Hydralazine treatment also significantly increased the survival rate from 60% to 100%. In conclusion, hydralazine inhibited AAA formation and rupture in a mouse model, which was associated with its anti-inflammatory and anti-apoptotic properties.

Analysis of Early Death after Elective Open Abdominal Aortic Aneurysm Repair

BACKGROUND

Mortality after open abdominal aortic aneurysm repair is a quality measure and early death may represent a technical complication or poor patient selection. Our objective was to analyze patients who died in the hospital within postoperative day (POD) 0-2 after elective abdominal aortic aneurysm repair.

METHODS

The Vascular Quality Initiative was queried from 2003-2019 for elective open abdominal aortic aneurysm repairs. Operations were categorized as in-hospital death on POD 0-2 (POD 0-2 Death), in-hospital death beyond POD 2 (POD ≥3 Death), and those alive at discharge. Univariable and multivariable analyses were performed.

RESULTS

There were 7,592 elective open abdominal aortic aneurysm repairs with 61 (0.8%) POD 0-2 Death, 156 (2.1%) POD ≥3 Death, and 7,375 (97.1%) alive at discharge. Overall, median age was 70 years and 73.6% were male. Iliac aneurysm repair and surgical approach (anterior/retroperitoneal) were similar among groups. POD 0-2 Death, compared to POD ≥3 Death and those alive at discharge, had the longest renal/visceral ischemia time, more commonly had proximal clamp placement above both renal arteries, an aortic distal anastomosis, longest operative time, and largest estimated blood loss (all P < 0.05). Postoperative vasopressor usage, myocardial infarction, stroke, and return to the operating room were most frequent in POD 0-2 Death and extubation in the operating room was least frequent (all P < 0.001). Postoperative bowel ischemia and renal failure occurred most commonly among POD ≥3 Death (all P < 0.001).On multivariable analysis, POD 0-2 Death was associated with congestive heart failure, prior peripheral vascular intervention, female sex, preoperative aspirin use, lower center volume quartile, renal/visceral ischemia time, estimated blood loss, and older age (all P < 0.05).

CONCLUSIONS

POD 0-2 Death was associated with comorbidities, center volume, renal/visceral ischemia time, and estimated blood loss. Referral to high-volume aortic centers could improve outcomes.

Predictors of 30-Day Postoperative Outcome after Elective Endovascular Abdominal Aortic Aneurysm Repair: A Tertiary Referral Center Experience

BACKGROUND

We evaluated the 30-day postoperative outcome after elective endovascular aneurysm repair (EVAR) and the possible predictors for the 30-day postoperative outcome.

MATERIALS

Demographics, medical history, laboratory values, intensive care unit (ICU) admission and 30-day complications classified as major (major adverse cardiovascular events (MACEs), acute kidney injury (AKI) and death of any cause) and minor (postimplantation syndrome (PIS), postoperative delirium (POD), urinary tract infection (UTI) and technical graft failure) were documented (March 2016 to February 2019).

RESULTS

We included 322 patients. The majority were managed under general anesthesia (83%) with femoral cutdown (98.1%). Overall, 121 (37.5%) complications, mostly minor (n = 103, 31.9%), were recorded. In total, 11 patients (3.4%) developed MACEs, 5 (1.6%) experienced AKI and 2 (0.6%) died in the ICU. Moreover, 77 patients (23.9%) suffered from PIS, 11 from POD, 11 from UTI and 4 from technical graft failure. The multivariate logistic regression analysis revealed that aneurysm diameter (p = 0.01) and past smoking (p = 0.003) were predictors for complications. PAD was an independent predictor of MACEs (p = 0.003), preoperative neutrophil to lymphocyte ratio (NLR) of AKI (p = 0.003) and past smoking of PIS (p = 0.008), respectively.

CONCLUSIONS

Our study showed that the 30-day morbidity after EVAR exceeded 35%. However, the majority of complications were minor, and the associated mortality was low. Aneurysm diameter and past smoking were independent predictors for postoperative outcome.

Aortobifemoral reconstruction in open abdominal aortic aneurysm repair is associated with increased morbidity and mortality

OBJECTIVE

Much attention has been given to the influence of anatomic and technical factors, such as maximum abdominal aortic aneurysm diameter and proximal clamp position, in open abdominal aortic aneurysm repair (OSR). However, no studies have rigorously examined the correlation between site of distal anastomosis and OSR outcomes despite conventional wisdom that more proximal sites of anastomosis are preferrable when technically feasible. This study aimed to test the association between sites of distal anastomosis and clinical outcomes for patients undergoing primary elective OSR.

METHODS

Our study included 5683 patients undergoing primary elective OSR at 233 centers from 2014 to 2020. Using a variety of statistical methods to account for potential confounders, including multivariable logistic regression and Cox proportional hazards modeling, as well as subgroup analysis, we examined the association between site of distal anastomosis and clinical outcomes in elective OSR. Primary outcomes were major in-hospital complication rate, 30-day mortality, and long-term survival.

RESULTS

Patients undergoing elective aortobifemoral reconstruction (n = 672) exhibited significantly increased rates of smoking, chronic obstructive pulmonary disease, and peripheral artery disease in comparison to patients undergoing elective OSR with distal anastomosis to the aorta (n = 2298), common iliac artery (n = 2163), or external iliac artery (n = 550). Patients undergoing aorto-aortic tube grafting were significantly less likely to exhibit iliac aneurysmal disease and significantly more likely to be undergoing elective OSR with a suprarenal or supraceliac proximal clamp position. Using multivariable logistic regression and Cox proportional hazards analysis to control for important confounders, such as age, smoking status, and medical history, we found that distal anastomosis to the common femoral artery was associated with increased odds of major in-hospital complications (adjusted odds ratio, 1.79; 95% confidence interval, 1.46-2.18; P < .001) and reduced long-term survival (adjusted hazard ratio, 1.44; 95% confidence interval, 1.09-1.89; P = .010). We observed no significant differences in 30-day mortality across sites of distal anastomosis in our study population.

CONCLUSIONS

It is generally accepted that more proximal sites of distal anastomosis should be selected in OSR when technically feasible. Our findings support this hypothesis by demonstrating that distal anastomosis to the common femoral artery is associated with increased perioperative morbidity and reduced long-term survival. Careful diligence regarding optimization of preoperative health status, perioperative care, and long-term follow-up should be applied to mitigate major complications in this patient population.

Influence of Operative Time in the Results of Elective Endovascular Repair of Abdominal Aortic Aneurysms

BACKGROUND

A prolonged operative time (OT) is a well-recognized risk factor of postoperative complications after many open surgical procedures, although little is known about its impact in less-invasive endovascular procedures. We aimed to define the characteristics related to a prolonged OT in the endovascular treatment of aorto-iliac aneurysms (EVAR) and to evaluate the influence of OT on postoperative outcomes.

METHODS

Retrospective analysis of 284 consecutive patients (mean age 75 years, 95% male) who underwent an elective EVAR between 2000 and 2019. Operative characteristics related to OT and the impact of OT in postoperative results was studied using multiple lineal and logistic regression analyses, respectively.

RESULTS

The mean surgical time was 200 min. OT was associated (regression model) with the implantation of straight endografts (-38 min, P = 0.007), femoral artery surgery (+80 min, P < 0.001), hypogastric preservation procedures (+70 min, P < 0.001), associated peripheral arterial disease (+22 min, P = 0.013), general anesthesia (+34 min, P < 0.001), and aneurysm diameter (+9 min/cm, P = 0.002). During the postoperative period (<30 days or at discharge), 21% presented a complication and 2.8% died. OT was independently associated with a higher incidence of postoperative complications (odds ratio [OR] for each additional 30' of surgery = 1.34, P < 0.001), such as immediate (OR = 1.48, P = 0.003) and 6-month mortality (OR = 1.28, P = 0.025).

CONCLUSIONS

A prolonged OT is an independent risk factor for complications and mortality after EVAR. Surgeons must take this factor into consideration when defining the best therapeutic strategy for abdominal aortic aneurysms.

Open Abdominal Aortic Aneurysm Surgery and Renal Dysfunction; Association of Demographic and Clinical Variables with Proximal Clamp Location

BACKGROUND

While cross-clamp site is a known risk factor for postoperative acute and chronic renal dysfunction following open abdominal aortic aneurysm surgery (AAA), the additive impact of patient demographic and clinical factors is lacking. In this study, we investigated the impact of body mass index (BMI), surgical duration and aneurysm diameter on the association between proximal cross-clamp location and postoperative renal dysfunction.

METHODS

In this study, we conducted a retrospective analysis of 4,197 patients undergoing open AAA surgery between 2011 and 2018 using data housed in the American College of Surgeons National Safety Quality Improvement Program (ACS-NSQIP) database. The primary outcome was renal dysfunction, which was defined as patients requiring dialysis within 30 days or patients with ≥2 mg/dL rise in creatinine from baseline. We assessed the incidence of renal dysfunction with regard to clamp location and subsequently used multivariable logistic regression to assess clinical and demographic factors associated with renal dysfunction. We used a regression model to plot the association of BMI, surgical duration, and aneurysm diameter with an adjusted probability of postoperative acute and chronic renal dysfunction for individual cross-clamp locations.

RESULTS

Of the 4,197 patients analyzed, 405 patients (9.6%) developed renal dysfunction within 30 days with 287 patients requiring dialysis. Patients with supraceliac clamp location had the highest incidence of renal dysfunction (20.4%). Our data showed a significant association of renal dysfunction with higher BMI patients [OR 1.04 (1.02, 1.07), P = 0.001], longer operative times [OR1.01 (1.01, 1.02), P < 0.001], clamp location between the superior mesenteric artery (SMA) and renal artery [OR 1.80 (1.17, 2.78), P = 0.007] and supraceliac clamp location [OR 2.47 (1.62, 3.76), P < 0.001].

CONCLUSIONS

The incidence of renal dysfunction increases with suprarenal clamps. Patients with higher BMI, longer operative times, and increasing aneurysm diameter, and a suprarenal clamp have a significantly increased risk of renal dysfunction compared to those who also had a suprarenal clamp but lower BMI, shorter operative times and smaller aneurysm diameter.

Military Surgical Team Performance: The Impact of Familiarity, Team Size, and Nurse Anesthesia Students

PURPOSE

To examine the key factors impacting surgical team performance in a military medical center.

DESIGN

A retrospective, exploratory, cross-sectional design.

METHODS

We reviewed 751 orthopedic surgical cases to determine the association of surgical team familiarity, surgical complexity, team size, and the presence of student registered nurse anesthetists (SRNAs) with the surgical performance measures of total operative time, turnover time, and on-time surgical start.

FINDINGS

We found increases in surgical team familiarity significantly reduced turnover time by 7.84% (1-0.9216 = 0.0784; P = .0260) after controlling for surgical complexity and the presence of an SRNA on the team. Familiarity did not significantly impact total operative time or the odds of a first case on-time start. With a significant interaction of surgical complexity and team size on total operative time, the surgical complexity marginal effect (at the mean of team size) showed that a one-point increase prolonged total operative time by 6.89% (P < .0001), after controlling for team familiarity and an SRNA. The team size marginal effect (at the mean of surgical complexity) showed that adding one member to the surgical team prolonged total operative time by 6.45% (P < .0001), after controlling for team familiarity and an SRNA. Higher surgical complexity not only increased turnover time by 1.46% (P = .0265) while holding surgical complexity and an SRNA presence constant, but also reduced the likelihood of an on-time surgical start by 0.9359 (P = .0060). Larger teams decreased the odds of an on-time start by 0.7750 (P = .0363). We found that SRNAs potentially offer efficiency benefits, as their presence on a surgical team was associated with a 0.82% (1-0.9185 = 0.0815; P = .0007) decrease in total operative time, and a 21.01% (1-0.7899=0.2101; P = .0002) reduction in expected turnover time, after adjusting for confounding variables.

CONCLUSIONS

Surgical efficiency is a modifiable function of surgical teams. Although we suggest additional research, surgical leaders can potentially improve team performance by improving familiarity and forming small and cohesive surgical teams. As OR inefficiencies degrade the financial vitality of healthcare systems, surgical leaders should engage in a multifaceted program to improve efficiency by building familiarity and optimizing team size.

Mouse models for abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) rupture is estimated to cause 200,000 deaths each year. Currently, the only treatment for AAA is surgical repair; however, this is only indicated for large asymptomatic, symptomatic or ruptured aneurysms, is not always durable, and is associated with a risk of serious perioperative complications. As a result, patients with small asymptomatic aneurysms or who are otherwise unfit for surgery are treated conservatively, but up to 70% of small aneurysms continue to grow, increasing the risk of rupture. There is thus an urgent need to develop drug therapies effective at slowing AAA growth. This review describes the commonly used mouse models for AAA. Recent research in these models highlights key roles for pathways involved in inflammation and cell turnover in AAA pathogenesis. There is also evidence for long non-coding RNAs and thrombosis in aneurysm pathology. Further well-designed research in clinically relevant models is expected to be translated into effective AAA drugs.

Influence of Operative Time in the Results of Infrainguinal Bypass for Chronic Limb Threatening Ischemia

BACKGROUND

An increased operative time (OT) has been associated with a higher rate of adverse outcomes after several surgical procedures although scarce evidence exists for infrainguinal bypass surgery (IBS) and its impact beyond the postoperative period. The aim of this study was to define surgical characteristics related to a prolonged OT in IBS for chronic limb threatening ischemia and its influence on postoperative and 1-year outcomes.

MATERIALS AND METHODS

Retrospective study of 249 consecutive patients (mean age 72.4 years, 73.1% male) undergoing IBS for CLI between 2008 and 2018. The characteristics related to the duration of surgery and its impact on outcome were assessed with a multiple linear regression and a multivariate logistic regression, respectively.

RESULTS

Interventions associated with a prolonged OT included the bypass to a below-the-knee artery (additional 36 min, p = 0.002), the need for an alternative vein or a hybrid PTFE-vein graft (additional 37 min, p = 0.02) and inflow associated procedures (additional 47 min, p < 0.001). OT was associated with a higher rate of postoperative complications (OR for each additional 30 min 1.123, 95% CI 1.021-1.234) and need for a sociosanitary facility at discharge (OR 1.143, 95% CI 1.033-1.265). At 1-year of follow-up, OT was related to a higher major amputation rate (OR 1.201, 95% CI 1.036-1.393) and non-significantly to mortality (OR 1.125, 95% CI 0.999-1.268).

CONCLUSIONS

A prolonged OT is a risk factor for adverse outcomes after IBS that extends beyond the immediate postoperative period. Further research is needed to evaluate how an expected high OT might influence decision-making.

Numerical study on the effect of stent shape on suture forces in stent-grafts

Second-generation stent-grafts (SGs) have addressed many of the mechanical problems reported for first-generation endoprostheses, such as graft tear and stent rupture; however, suture wear and detachment due to pulsatile fatigue remains an issue. Numerical studies on the mechanical behavior of these endoprostheses usually model the attachment between stents and graft as a continuous ''tie'' constraint, which does not provide information on the mechanical loads acting on individual sutures. This paper presents a suitable approach for Finite Element (FE) simulations of SGs which allows for a qualitative evaluation of the loads acting on sutures. Attachment between stents and graft is modeled as rigid beams at discrete locations of the endoprostheses, and the reaction forces on the beams are analyzed. This modeling strategy is employed for four different SG models (two Z-stented commercial models and two circular-stented models) subjected to a severe 180° U-bend, followed by intraluminal pressurization. Results show that, for all models, the majority of sutures is experiencing fluctuating forces within a cardiac cycle (between 80 and 120 mmHg), which points to pulsatile fatigue as potential failure mode. In addition, the highest loads are concentrated in kinks and, for Z-stented models, at the apexes of stents. Moreover, suture loads for circular-stented models are lower than for Z-stented models, indicating better resistance to suture detachment. All these observations are in line with experimental results published in the literature, and, therefore, the procedure herein proposed may serve as a valuable tool in the development of new SG models with better suture resistance to pulsatile wear and fatigue.

The effect of Endovascular Aneurysm Repair on Renal Function in Patients Treated for Abdominal Aortic Aneurysm

Aim:

The effect of endovascular aneurysm repair in patients treated for abdominal aortic aneurysm has not been clearly defined. The objective of the present article was to provide a contemporary literature review and perform an analysis to determine the effect of EVAR on renal function in the early post-operative period and during follow-up.

Methods:

A systematic review of the literature was undertaken to identify all studies reporting the effect of EVAR on renal function. Outcome data were pooled and combined overall effect sizes were calculated using fixed or random-effects models.

Results:

Thirty-two studies reporting on 24846 patients were included. Acute renal failure after EVAR occurred with an estimated frequency of 9% (95%CI: 5-16%; I2=97%). Median follow-up period was 19.5 months (range 1-60 months). The estimated frequency of chronic renal failure during follow-up was 7% (95%CI: 3-17%; I2=98%). Hemodialysis was required in 2% (1-3%; I2=97%) of the cases.

Conclusion:

High-level evidence demonstrating the effect of EVAR on the incidence of acute and chronic renal failure is lacking. Based on the current available data, nearly 10% of patients undergoing EVAR for AAA have an increased risk for renal dysfunction after the procedure. Whether this deterioration may lead to a worse outcome has not been adequately proved.