The Contemporary Impact of Body Mass Index on Open Aortic Aneurysm Repair

INTRODUCTION

The Centers for Disease Control and Prevention (CDC) has deemed obesity a national epidemic and contributor to other leading causes of death including heart disease, stroke, and diabetes. Accordingly, the role of body mass index (BMI) and its impact on surgical outcomes has been a focus of persistent investigation. The purpose of this study was to quantify the effect of BMI on open abdominal aortic aneurysm repair (oAAA) outcomes in contemporary practice.

METHODS

All elective oAAAs in the VQI (2010-2021) were identified. End-points included 30-day death, in-hospital complications and 1-year mortality. Patients were stratified into four BMI cohorts (BMI<18.5, 18.5≤BMI<25, 25≤BMI<30, BMI≥30). Spline interpolation was used to explore a potential non-linear association between BMI and perioperative mortality. Mixed-effects Cox regression was used to assess the association between BMI and 1-year survival.

RESULTS

9,479 patients underwent oAAA over the study interval (median age-70, 74%-male, BMI 27±6). Lower BMI patients(<18.5) compared to higher BMI(>30) patients were more likely to be women (53% vs. 32%;p<.0001), current smokers(65% vs. 50%;p<.0001), and have COPD(58% vs. 37%;p<.0001). In contrast, an increased BMI was associated with a greater prevalence of diabetes and CAD (DM-26% vs. 6%;p<.0001; CAD-27% vs. 20%;p=.01). There was no difference in cross-clamp position or visceral/renal bypass between groups, though low BMI patients necessitated more frequent infrainguinal bypass(5% vs. 2%;p=.0002). 30-day mortality and in-hospital complications were greater among low BMI patients(30-day mortality:12% vs. 4%;p<.0001;complications-47% vs. 37%;p<.0001). Interestingly, low BMI conferred a nearly 2-fold increase in observed pulmonary complications(18% vs. 11%;p<.0001). Surgical site infections were twice as common among the lowest and highest BMI groups(4% vs. 2%;p<.0001). 1-year mortality was greatest among low BMI patients(23% vs. 9%;p<.0001). Adjusted spline-fit analysis demonstrated increased mortality among patients with BMI<21 or >34(BMI<18.5-HR 2.1, 95%CI 1.6-2.8;p<.0001; BMI>34-HR 1.3, 95%CI 1.1-1.6;p=.009).

CONCLUSION

Both low (<18.5) and high (>34) BMI were associated with increased oAAA mortality in current practice. Despite the perception that obesity confers substantial surgical risk during oAAA, diminished BMI was associated with a 3-fold increase in 30-day and 1-year mortality. It appears that BMI extremes are distinct proxies for differential clinical phenotypes and should inform risk stratification for oAAA repair.

The Utility of the Bilateral Temporal Artery Biopsy for Diagnosis of Giant Cell Arteritis

OBJECTIVE

A surgical temporal artery biopsy (TAB) is the gold standard for diagnosis of giant cell arteritis (GCA). The necessity of performing a bilateral biopsy remains under debate. The primary objective of this study was to assess the rate of discordance between pathology results in patients who underwent bilateral temporal artery biopsy for suspected GCA.

METHODS

We performed a retrospective review of patients who underwent bilateral temporal artery biopsy for diagnosis of GCA between 2011 and 2020. The primary endpoint was the rate of discordance between specimens for patients with pathology positive GCA. Secondary endpoints included assessments of the sensitivity of pre-operative temporal artery duplex and the effects of specimen length and specialty of referring provider on the diagnostic yield of the biopsy.

RESULTS

During the study period, 310 patients underwent bilateral temporal artery biopsy for diagnosis of giant cell arteritis. These patients were primarily female (73.9%), elderly (mean age 70.8 years), and Caucasian (95.8%). Pre-operative symptoms for patients were typically bilateral (59%) and included headache (81%), vision changes (45.2%), and temporal tenderness (32.6%). Most patients (85.2%) were on pre-operative steroid therapy at the time of surgical biopsy with a mean pre-operative duration of steroid therapy of 15.1 days. Overall, 91 patients (29.4%) had a positive pathologic diagnosis after bilateral temporal artery biopsy. Of these patients, 11 had a positive pathology result in only a single specimen, resulting in a discordance rate of 12.1%. Pre-operative temporal artery duplex demonstrated low sensitivity (27.3%) for identifying patients with pathologic positive disease. There were no significant differences between the pathology positive and negative patients in terms of mean surgical specimen length (1.67 vs 1.64 cm; p = 0.67) or specialty of referring provider (p = 0.73).

CONCLUSIONS

At our institution, we observed a 12.1% discordance rate between pathology results in patients who underwent bilateral temporal artery biopsy for diagnosis of GCA. A pre-operative temporal artery duplex provided little value in identifying patients with biopsy-proven GCA.

Venous status ulcers due to congenital agenesis of the inferior vena cava in a 16-year-old male

We report a case of agenesis of the infrarenal inferior vena cava in a 16-year-old male presenting with venous stasis dermatitis and ulceration in the gaiter region bilaterally. Duplex imaging was performed revealing absence of infrarenal inferior vena cava and iliofemoral venous system. Magnetic resonance venography then confirmed the above findings along with revealing extensive lumbar and pelvic collateralization. This patient's condition has been successfully managed conservatively with compression therapy and wound care. This case is a rare example of a congenital malformation of the inferior vena cava and represents the only reported case with presenting symptoms of venous stasis ulceration in a pediatric patient.

Two case presentations and surgical management of Bow Hunter's syndrome associated with bony abnormalities of the C7 vertebra

Bow Hunter's syndrome is a condition in which patients experience vertebrobasilar symptoms on head turn. It may be a consequence of intrinsic factors such as atherosclerosis, or it may be secondary to mechanical compression. Most commonly, this occurs at the level of C2 or above. We present two rare cases of Bow Hunter's syndrome secondary to mechanical compression at the level of C7. Discussed are the anatomic conditions leading to this syndrome in these two patients, the methodology for confirming the diagnosis, and the successful management by partial resection of the transverse processes compressing the vertebral arteries.

Clinical course of asymptomatic patients with carotid duplex scan end diastolic velocities of 100 to 124 centimeters per second

OBJECTIVE

With the decline of diagnostic angiography, clinicians increasingly rely upon duplex scan criteria to select appropriate asymptomatic candidates for carotid intervention. Some recent trials have enrolled patients for intervention based upon end diastolic velocities (EDVs) as low as 100 cm/second, and peak systolic velocities (PSVs) as low as 230 cm/second. In as much as we have used more selective duplex scan criteria, we reviewed the course of asymptomatic patients who had EDVs from 100 to 124 cm/second.

METHODS

Of the patients evaluated in our Intersocietal Commission for the Accreditation of Vascular Laboratories (ICAVL) accredited laboratory from 2002 to 2007, 144 patients had an EDV 100 to 124 cm/second. Of these, 47 patients underwent initial carotid intervention for concomitant symptoms (10), contralateral occlusion (3), or other imaging findings felt to warrant intervention. The remaining 97 asymptomatic patients were followed. One patient had both arteries fall within this EDV range. The mean follow-up for the 98 arteries was 29.1 months (range, 2-116 months).

RESULTS

Five patients (5.2%) developed ipsilateral symptoms consisting of one stroke and four transient ischemic attacks (TIAs), at a mean time of 35.3 months (range, 12-58 months). Twenty-six patients (26.8%), including 3 who also developed ipsilateral symptoms, progressed to having an EDV of ≥ 125 cm/second at a mean time of 24 months (range, 2-58). Two of these (2.1%) progressed directly to occlusion without symptoms and with no documented interim worsening of stenosis.

CONCLUSION

For asymptomatic individuals with an initial EDV of 100 to 124 cm/second, the risk of ipsilateral stroke is small and, therefore, medical management is appropriate in most cases. However, the risk of progression to a more severe degree of stenosis, often warranting carotid intervention, is clinically meaningful. Yearly duplex scan follow-up is necessary to assess disease progression in this patient cohort.

Characterization of lymphoid DC during the resolution of Listeria monocytogenes infection (43.38)

Introduction: Dendritic cells are critical to innate immune responses based on their ability to secrete inflammatory cytokines and prime naïve T-cells. The role of DC during later stages of infection is not known.

Methods: Lymphoid DC (CD11c+CD8+NK1.1−B220−) were analyzed by flow cytometry and isolated by fluorescence activated cell sorting from the spleens of C57BL/6 mice infected with 5000 CFU of LM strain 10403s by tail vein injection. Mixed leukocyte reaction (MLR) was performed with 1x105 allogeneic T cells and 3x104 lymphoid DC.

Results: Following 24 hours of infection lymphoid DC accounted for 11% of conventional DC (CD11c+B220−NK1.1−) and had high expression of MHC II, CD40 and CD86. After 7 days of infection lymphoid DC increased to 47% of conventional DC and had less MHC II, CD40 and CD86 expression than uninfected controls. Lymphoid DC also lost their ability to stimulate allogeneic T cells in the MLR (6634±466 CPM for 12 hours of infection vs 320±80 for 7 days of infection).

Conclusion: Dynamic changes occur in the lymphoid DC compartment during the resolution phase of LM infection.

This work was supported by grant DK068346.

Liver plasmacytoid dendritic cells stimulate antigen specific T cells in vivo (36.16)

Introduction: Liver plasmacytoid dendritic cells (pDC) are considered to be weak stimulators of in vitro T cell responses. We sought to determine their ability to prime an antigen specific T cell response in vivo.

Methods: C57BL/6 murine spleen and liver pDC (CD11c+B220+NK1.1−CD19−CD11b−) were expanded in vivo with the use of an adenovirus encoding murine Flt3L cDNA and isolated by fluorescence activated cell sorting. CD45.2+ CFSE-labeled OT-I T cells were injected in the lateral tail vein of congenic recipient CD45.1 mice, pDC loaded with OVA257–264 (1μg/ml) or TRP-2181–188 (1μg/ml) were subsequently injected into the footpad. Three days later popliteal nodal lymphocytes were analyzed by flow cytometry for dissolution of CFSE fluorescence among CD3+CD8+CD45.2+cells.

Results: Flt3L expanded OVA257–264 loaded liver pDC and spleen pDC caused 70% and 79% respectively of the transferred T cells to divide. TRP-2181–188 loaded pDC induced no T cell division.

Conclusion: Liver pDC can initiate antigen specific T cell responses in vivo.

This work was supported by grant DK068346.

Listeria induces NKDC to produce IFN-gamma via IL-12, IL-18 and TLR9 ligation (44.24)

Introduction: Natural killer dendritic cells (NKDC, NK1.1+CD11c+) are innate effector cells that secrete IFN-γ when stimulated. Initial control of Listeria monocytogenes (LM) infection depends on IFN-γ. The mechanism of IFN-γ secretion by NKDC in response to LM is unknown.

Methods: NKDC and NK (NK1.1+CD3−) cells were isolated by fluorescence activated cell sorting from the spleens of C57BL/6 mice and cultured with LM strain 10403s at a multiplicity of infection of 1 for 3 days. IL-18 (20ng/ml), IL-12 blocking antibody (10μg/ml), or an inhibitory CpG (iCpG) sequence (50μg/ml) was added. Supernatant IFN-γ was analyzed by cytometric bead array.

Results: LM infection or IL-18 alone did not induce significant IFN-γ production by NK cells or NKDC, however the combination of IL-18 and LM induced substantial amounts of IFN-γ from NKDC (19.3±2.7 ng/ml), and to a lesser extent, NK cells (2.0±0.6 ng/ml). Addition of anti-IL-12 antibody abrogated the IL-18/LM induced IFN-γ production of both NK cells and NKDC (&lt;0.4 ng/ml). The addition of iCpG led to an 85% reduction of IL-18/LM induced IFN-γ production by NKDC and a 20% reduction by NK cells.

Conclusion: IL-18, IL-12, and TLR9 ligation regulate NKDC IFN-γ production in response to LM.

This work was supported by grant DK068346.