Access Site Complications Are Uncommon with Vascular Closure Devices or Manual Compression after Lower Extremity Revascularization

OBJECTIVE

Vascular closure devices (VCD) and manual compression (MC) are used to achieve hemostasis following peripheral vascular interventions (PVI). We sought to compare perioperative outcomes between MC and four VCDs following PVI in a multicenter setting.

METHODS

The Vascular Quality Initiative was queried for all lower extremity (LE) PVIs with common femoral artery access performed from 2010-2020. VCDs included were MynxGrip® (Cordis, Santa Clara, CA, USA), StarClose SE™ (Abbott, Redwood City, CA, USA), Angio-Seal® (Terumo, Somerset, NJ, USA), and Perclose ProGlide™ (Abbott, Redwood City, CA, USA). In a blinded fashion, these four VCDs (A, B, C, D) were compared to MC for baseline characteristics, procedural details, and outcomes (access site hematoma and stenosis/occlusion). Sheath size >8 Fr were excluded. Propensity score matching (1:1) was performed. Univariable and multivariable analyses were completed for unmatched and matched data.

RESULTS

There were 84,172 LE PVIs identified: 32,013 (38%) used MC and 52,159 (62%) used VCDs (A-12,675;B-6,224;C-19,872;D-13,388). Overall, average age was 68.7 years and 60.4% were male; indications for intervention were most commonly claudication (43.8%) and tissue loss (40.1%). When compared to MC, VCDs were utilized more often in patients with obesity, diabetes, and end stage renal disease (all P<.001). VCDs were used less often in patients with hypertension, chronic obstructive pulmonary disease, coronary artery disease, prior percutaneous coronary and extremity interventions, and major amputation (all P<.001). VCD use was more common, compared to MC, during femoral-popliteal (73% vs. 63.8%) and tibial interventions (33.8% vs. 22.3%), but less common with iliac interventions (20.6% vs. 34.7%) (all P<.001). Protamine was used less often after VCDs (19.1% vs. 25.6%, P<.001). Overall, there were 2,003 (2.4%) hematomas of which 278 (13.9%) required thrombin/surgical intervention. When compared to MC, any VCD use had fewer hematomas (1.7% vs. 3.6%, P<.001) and hematomas requiring intervention (.2% vs. .5%, P<.001). When divided by hemostatic technique, any hematoma were MC-3.6%; A-1.4%; B-1.2%; C-2.3%; D-1.1%, P<.001. Hematomas requiring intervention were MC-.5%; A-.2%; B-.2%; C-.3%; D-.1%, P<.001. Access site stenosis/occlusion was similar between MC and any VCDs (.2% vs. .2%, P=.12). Multivariable analysis demonstrated that any VCDs and individual VCDs, vs. MC, were independently associated with fewer hematomas. Access site stenosis/occlusion was similar between any VCDs and MC. Matched analysis revealed similar findings.

CONCLUSIONS

Although overall rates of hematomas requiring intervention were low regardless of hemostatic technique, VCD use, irrespective of type, compared favorably to MC with significantly fewer access site complications after PVI.

Outcomes of Axillofemoral Bypass for Intermittent Claudication

OBJECTIVE

While endovascular therapy is often first-line treatment for medically refractory intermittent claudication (IC) caused by aorto-femoral disease, suprainguinal bypass is commonly performed. Although this is often aorto-femoral bypass (AoFB), axillo-femoral bypass (AxFB) is still sometimes performed despite limited data evaluating its utility in the management of IC. Our goal was to assess the safety and durability of AxFB performed for IC.

METHODS

The Vascular Quality Initiative (2009-2019) was queried for suprainguinal bypass performed for IC. Univariable and multivariable analyses were used to compare perioperative and one-year outcomes between AxFB and a comparison cohort of AoFB.

RESULTS

We identified 3,261 suprainguinal bypasses performed for IC: 436 AxFB and 2,825 AoFB. Overall, mean age was 61.4 ± 9.1 years, 58.8% of patients were male sex, and 59.7% currently smoked. Patients undergoing AxFB, compared with AoFB, were more often older, male, never-smokers, and ambulated with assistance (all P<.001). They more often had hypertension, diabetes, coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease, end-stage renal disease, previous outflow peripheral endovascular interventions, and previous inflow or outflow bypass. AxFB, compared with AoFB, were more often uni-femoral (all P<.05). Patients undergoing AxFB, compared with AoFB, had shorter postoperative length of stay (median 4 vs. 6 days) and fewer perioperative pulmonary (3% vs. 7.9%) and renal complications (5.5% vs. 9.9%), but more perioperative ipsilateral major amputations (.9% vs. 0.04%) (all P<.05). There were no significant differences in perioperative myocardial infarction (2.8% vs. 2.7%), stroke (.7% vs. 1.1%), and death (1.8% vs. 1.7%) rates, respectively. At one year, Kaplan-Meier analysis demonstrated that the AxFB, compared with AoFB cohort, exhibited higher rates of death (7.3% vs. 3.6%, P=.002); graft occlusion or death (14.3% vs. 7.2%, P=.001); ipsilateral major amputation or death (12.5% vs. 5.6%, P<.001); and reintervention, amputation, or death (19% vs. 8.6%, P<.001). On multivariable analysis, AxFB was independently associated with increased risk of one-year reintervention, amputation, or death (HR 1.6, 95% CI 1.03-2.4, P=.04).

CONCLUSIONS

This retrospective analysis suggests that long-term complications were more frequent in patients who underwent AxFB as compared to AoFB, although patients treated with AxFB were at higher risk with more comorbidities. Since AxFB is associated with significant perioperative morbidity, mortality, and long-term complications, serious consideration should be given prior to its use for IC.

Diverse biological processes coordinate the transcriptional response to nutritional changes in a Drosophila melanogaster multiparent population

Background

Environmental variation in the amount of resources available to populations challenge individuals to optimize the allocation of those resources to key fitness functions. This coordination of resource allocation relative to resource availability is commonly attributed to key nutrient sensing gene pathways in laboratory model organisms, chiefly the insulin/TOR signaling pathway. However, the genetic basis of diet-induced variation in gene expression is less clear.

Results

To describe the natural genetic variation underlying nutrient-dependent differences, we used an outbred panel derived from a multiparental population, the Drosophila Synthetic Population Resource. We analyzed RNA sequence data from multiple female tissue samples dissected from flies reared in three nutritional conditions: high sugar (HS), dietary restriction (DR), and control (C) diets. A large proportion of genes in the experiment (19.6% or 2471 genes) were significantly differentially expressed for the effect of diet, and 7.8% (978 genes) for the effect of the interaction between diet and tissue type (LRT, P_adj. < 0.05). Interestingly, we observed similar patterns of gene expression relative to the C diet, in the DR and HS treated flies, a response likely reflecting diet component ratios. Hierarchical clustering identified 21 robust gene modules showing intra-modularly similar patterns of expression across diets, all of which were highly significant for diet or diet-tissue interaction effects (FDR P_adj. < 0.05). Gene set enrichment analysis for different diet-tissue combinations revealed a diverse set of pathways and gene ontology (GO) terms (two-sample t-test, FDR < 0.05). GO analysis on individual co-expressed modules likewise showed a large number of terms encompassing many cellular and nuclear processes (Fisher exact test, P_adj. < 0.01). Although a handful of genes in the IIS/TOR pathway including Ilp5, Rheb, and Sirt2 showed significant elevation in expression, many key genes such as InR, chico, most insulin peptide genes, and the nutrient-sensing pathways were not observed.

Conclusions

Our results suggest that a more diverse network of pathways and gene networks mediate the diet response in our population. These results have important implications for future studies focusing on diet responses in natural populations.

Learning to collaborate: bringing together behavior and quantitative genomics

The genetic basis of complex trait like learning and memory have been well studied over the decades. Through those groundbreaking findings, we now have a better understanding about some of the genes and pathways that are involved in learning and/or memory. However, few of these findings identified the naturally segregating variants that are influencing learning and/or memory within populations. In this special issue honoring the legacy of Troy Zars, we review some of the traditional approaches that have been used to elucidate the genetic basis of learning and/or memory, specifically in fruit flies. We highlight some of his contributions to the field, and specifically describe his vision to bring together behavior and quantitative genomics with the aim of expanding our knowledge of the genetic basis of both learning and memory. Finally, we present some of our recent work in this area using a multiparental population (MPP) as a case study and describe the potential of this approach to advance our understanding of neurogenetics.

Multiple genetic loci affect place learning and memory performance in Drosophila melanogaster

Learning and memory are critical functions for all animals, giving individuals the ability to respond to changes in their environment. Within populations, individuals vary, however the mechanisms underlying this variation in performance are largely unknown. Thus, it remains to be determined what genetic factors cause an individual to have high learning ability and what factors determine how well an individual will remember what they have learned. To genetically dissect learning and memory performance, we used the Drosophila synthetic population resource (DSPR), a multiparent mapping resource in the model system Drosophila melanogaster, consisting of a large set of recombinant inbred lines (RILs) that naturally vary in these and other traits. Fruit flies can be trained in a "heat box" to learn to remain on one side of a chamber (place learning) and can remember this (place memory) over short timescales. Using this paradigm, we measured place learning and memory for ~49 000 individual flies from over 700 DSPR RILs. We identified 16 different loci across the genome that significantly affect place learning and/or memory performance, with 5 of these loci affecting both traits. To identify transcriptomic differences associated with performance, we performed RNA-Seq on pooled samples of seven high performing and seven low performing RILs for both learning and memory and identified hundreds of genes with differences in expression in the two sets. Integrating our transcriptomic results with the mapping results allowed us to identify nine promising candidate genes, advancing our understanding of the genetic basis underlying natural variation in learning and memory performance.

The evolutionary potential of diet-dependent effects on lifespan and fecundity in a multi-parental population of Drosophila melanogaster

The nutritional conditions experienced by a population have a major role in shaping trait evolution in many taxa. Constraints exerted by nutrient limitation or nutrient imbalance can influence the maximal value that fitness components such as reproduction and lifespan attains, and organisms may shift how resources are allocated to different structures and functions in response to changes in nutrition. Whether the phenotypic changes associated with changes in nutrition represent an adaptive response is largely unknown. Further, it is unclear whether the response of fitness components to diet even has the potential to evolve in most systems. In this study, we use an admixed multi-parental population of Drosophila melanogaster reared in three different diet conditions to estimate quantitative genetic parameters for lifespan and fecundity. We find significant genetic variation for both traits in our population and show that lifespan has moderate to high heritabilities within diets. Genetic correlations for lifespan between diets were significantly less than one, demonstrating a strong genotype by diet interaction. These findings demonstrate substantial standing genetic variation in our population that is comparable to natural populations and highlights the potential for adaptation to changing nutritional environments.

A model-based high throughput method for fecundity estimation in fruit fly studies

The ability to quantify fecundity is critically important to a wide range of experimental applications, particularly in widely-used model organisms such as Drosophila melanogaster. However, the standard method of manually counting eggs is time consuming and limits the feasibility of large-scale experiments. We develop a predictive model to automate the counting of eggs from images of eggs removed from the media surface and washed onto dark filter paper. Our method uses the simple relationship between the white area in an image and the number of eggs present to create a predictive model that performs well even at high egg densities where clumping can complicate the individual identification of eggs. A cross-validation approach demonstrates our method performs well, with a correlation between predicted and manually counted values of 0.88. We show how this method can be applied to a large data set where egg densities vary widely.

How to get the most bang for your buck: the evolution and physiology of nutrition-dependent resource allocation strategies

All organisms use resources to grow, survive and reproduce. The supply of these resources varies widely across landscapes and time, imposing ultimate constraints on the maximal trait values for allocation-related traits. In this review, we address three key questions fundamental to our understanding of the evolution of allocation strategies and their underlying mechanisms. First, we ask: how diverse are flexible resource allocation strategies among different organisms? We find there are many, varied, examples of flexible strategies that depend on nutrition. However, this diversity is often ignored in some of the best-known cases of resource allocation shifts, such as the commonly observed pattern of lifespan extension under nutrient limitation. A greater appreciation of the wide variety of flexible allocation strategies leads directly to our second major question: what conditions select for different plastic allocation strategies? Here, we highlight the need for additional models that explicitly consider the evolution of phenotypically plastic allocation strategies and empirical tests of the predictions of those models in natural populations. Finally, we consider the question: what are the underlying mechanisms determining resource allocation strategies? Although evolutionary biologists assume differential allocation of resources is a major factor limiting trait evolution, few proximate mechanisms are known that specifically support the model. We argue that an integrated framework can reconcile evolutionary models with proximate mechanisms that appear at first glance to be in conflict with these models. Overall, we encourage future studies to: (i) mimic ecological conditions in which those patterns evolve, and (ii) take advantage of the 'omic' opportunities to produce multi-level data and analytical models that effectively integrate across physiological and evolutionary theory.

The Role of the Model of End-Stage Liver Disease Score in Predicting Outcomes of Carotid Endarterectomy

Objectives:

The Model of End-Stage Liver Disease (MELD) score has been traditionally utilized to prioritize for liver transplantation; however, recent literature has shown its value in predicting surgical outcomes for patients with hepatic dysfunction. The benefit of carotid endarterectomy in asymptomatic patients is dependent on low perioperative morbidity. Our objective was to use MELD score to predict outcomes in asymptomatic patients undergoing carotid endarterectomy.

Methods:

Patients undergoing carotid endarterectomy were identified in the National Surgical Quality Improvement Program data sets from 2005 to 2012. The Model of End-Stage Liver Disease score was calculated using serum bilirubin, creatinine, and the international normalized ratio (INR). Patients were grouped into low (<9), moderate (9-14), and high (15+) MELD classifications. The effect of the MELD score on postoperative morbidity and mortality was assessed by multivariable logistic and gamma regressions and propensity matching.

Results:

There were 7966 patients with asymptomatic carotid endarterectomy identified. The majority 5556 (70%) had a low MELD score, 1952 (25%) had a moderate MELD score, and 458 (5%) had a high MELD score. High MELD score was independently predictive of postoperative death, increased length of stay, need for transfusion, pulmonary complications, and a statistical trend toward increased cardiac arrest/myocardial infarction. The Model of End-Stage Liver Disease score did not affect postoperative stroke, wound complications, or operative time.

Conclusion:

High MELD score places asymptomatic patients undergoing carotid endarterectomy at a higher risk of adverse outcomes in the 30 days following surgery. This provides further empirical evidence for risk stratification when considering treatment for these patients. Outcomes of medical management or carotid stenting should be investigated in high-risk patients.

Identifying Loci Contributing to Natural Variation in Xenobiotic Resistance in Drosophila

Natural populations exhibit a great deal of interindividual genetic variation in the response to toxins, exemplified by the variable clinical efficacy of pharmaceutical drugs in humans, and the evolution of pesticide resistant insects. Such variation can result from several phenomena, including variable metabolic detoxification of the xenobiotic, and differential sensitivity of the molecular target of the toxin. Our goal is to genetically dissect variation in the response to xenobiotics, and characterize naturally-segregating polymorphisms that modulate toxicity. Here, we use the Drosophila Synthetic Population Resource (DSPR), a multiparent advanced intercross panel of recombinant inbred lines, to identify QTL (Quantitative Trait Loci) underlying xenobiotic resistance, and employ caffeine as a model toxic compound. Phenotyping over 1,700 genotypes led to the identification of ten QTL, each explaining 4.5-14.4% of the broad-sense heritability for caffeine resistance. Four QTL harbor members of the cytochrome P450 family of detoxification enzymes, which represent strong a priori candidate genes. The case is especially strong for Cyp12d1, with multiple lines of evidence indicating the gene causally impacts caffeine resistance. Cyp12d1 is implicated by QTL mapped in both panels of DSPR RILs, is significantly upregulated in the presence of caffeine, and RNAi knockdown robustly decreases caffeine tolerance. Furthermore, copy number variation at Cyp12d1 is strongly associated with phenotype in the DSPR, with a trend in the same direction observed in the DGRP (Drosophila Genetic Reference Panel). No additional plausible causative polymorphisms were observed in a full genomewide association study in the DGRP, or in analyses restricted to QTL regions mapped in the DSPR. Just as in human populations, replicating modest-effect, naturally-segregating causative variants in an association study framework in flies will likely require very large sample sizes.

Dissecting complex traits using the Drosophila Synthetic Population Resource

For most complex traits we have a poor understanding of the positions, phenotypic effects, and population frequencies of the underlying genetic variants contributing to their variation. Recently, several groups have developed multi-parent advanced intercross mapping panels in different model organisms in an attempt to improve our ability to characterize causative genetic variants. These panels are powerful and are particularly well suited to the dissection of phenotypic variation generated by rare alleles and loci segregating multiple functional alleles. We describe studies using one such panel, the Drosophila Synthetic Population Resource (DSPR), and the implications for our understanding of the genetic basis of complex traits. In particular, we note that many loci of large effect appear to be multiallelic. If multiallelism is a general rule, analytical approaches designed to identify multiallelic variants should be a priority for both genome-wide association studies (GWASs) and multi-parental panels.