Median arcuate ligament syndrome: a cost analysis to determine the economic burden of a rarely diagnosed disease

Background

Chronic abdominal pain (CAP) is a medical condition resulting in enormous economic burden and healthcare utilization costs. One understudied source of CAP is the median arcuate ligament syndrome (MALS). MALS is often not diagnosed and treated for a variety of reasons, including the fact that MALS is highly comorbid with psychological symptoms and psychiatric disorders similar to CAP. To better inform future work on the study of MALS, we undertook a pilot study to estimate the economic impact and public health burden of this condition. We hypothesized that MALS imposes a significant public health burden.

Methods

Pediatric and adult patients enrolled in a prospective study undergoing multidisciplinary evaluation and treatment for MALS at a tertiary care facility were invited to participate in a brief self-report survey, the Direct and Indirect Medical Care Impact of MALS Form, to capture health care resources including procedures, surgeries, health care visits, and absenteeism (school and work). To estimate costs from the Direct and Indirect Medical Care Impact of MALS Form, the medical care usage data self-reported by patients were converted to dollar value utilizing FSC-93 billing data and corresponding current procedural terminology (CPT) codes for procedures and provider visits one year prior to surgery and then following surgery. Descriptive analyses were conducted to characterize the sample in terms of demographics and reported absences from school and work.

Results

One hundred and nineteen patients (mean age = 30.9 ± 13.0) completed the questionnaires, yielding a 57% response rate. 82.4% (n = 98) of the participants were female and 90.8% (n = 108) were non-Hispanic/Latine white. The mean and median surgical follow-up periods were 5.3 and 5.4 years, respectively. Overall, median cost of provider and ancillary healthcare provider visits for each patient was (US)$19,119 including the pre-operative and post-operative visits. The mean cost for providers alone was (US)$28,908. Wilcoxon signed-ranks tests indicated that the postoperative missed number of days of school were significantly lower than the pre-surgical number of missed school days (Z = -3.36, p = 0.001). Similarly, there were significantly less missed work-days following surgery than before for the entire sample (Z = -2.86, p = 0.004).

Conclusion

Median arcuate ligament syndrome imposes a large economic burden on patients and the healthcare system. The current findings, although reflective of a homogenous population, are adding to a growing body of literature suggesting that healthcare disparities play a role in the low rates of diagnosis and treatment of MALS.

Patient-Reported Experiences With Median Arcuate Ligament Syndrome: Resilience and Resources Required

Objective

Median arcuate ligament syndrome (MALS) is a vascular condition that is treated surgically. MALS is a diagnosis of exclusion and therefore often requires that pediatric patients undergo an exhaustive number of tests and potential experiences with misdiagnosis before receiving an accurate diagnosis and treatment. The purpose of the current mixed-methods study was to assess the pediatric patient- and parent-reported experience of (a) coping with and managing symptoms associated with MALS and (b) the diagnostic, treatment, and recovery process for pediatric MALS.

Methods

Nine postsurgical pediatric patients (M age = 20.11 ± 3.59; all <18 at time of surgery) and 6 parents participated in semistructured focus groups and completed self-report questionnaires about their experiences and current functioning.

Results

Four themes emerged: (a) the impact of MALS (physical and psychosocial), (b) uncertainties and feeling misunderstood, (c) extensive medical tests, and (d) mental health impacts, with an additional three themes related to specific querying (i.e., appreciation, recommendations, and interdisciplinary treatment team). With the exception of variable long-term physical impacts, patients and their parents reported fairly consistent experiences, and the content of these themes was consistent with self-reported quantitative data.

Conclusions

The current study highlights the resilience and resources seemingly required for effective diagnosis and intervention for pediatric MALS. The need for increased knowledge about MALS, the inclusion of an interdisciplinary treatment team, and long-term follow-up for pediatric patients with MALS are implicated.

Targeting Coping to Improve Surgical Outcomes in Pediatric Patients With Median Arcuate Ligament Syndrome: Feasibility Study

Background: Median arcuate ligament syndrome (MALS) is a vascular compression syndrome leading to postprandial epigastric pain, nausea, and weight loss; it can be treated surgically. While most patients report improved quality of life following surgical intervention, 30% continue to experience chronic abdominal pain. Pre-surgical diagnoses of depression and/or anxiety have been found to significantly predict post-surgical: quality of life, highest experience of pain, anxiety, and parent- and self-reported coping strategies. As such, increasing the coping strategies of pediatric patients with MALS may impact their post-surgical outcomes. The purpose of the current study was to: (1) implement a pre-operative cognitive behavioral therapy protocol with a focus on psychoeducation and coping strategies; and (2) determine feasibility of a pre-surgical intervention for this population. Method: Children (<18 years of age) with a diagnosis of MALS who were eligible for surgical intervention were invited to participate in a 7-week in-person or video-based pre-surgical cognitive behavioral therapy intervention. Psychiatric comorbidities were assessed at baseline and post-surgery; patient-reported distress, pain interference and intensity, health-related quality of life, and health status were assessed at four time points (baseline, week 4, week 7, and post-surgery). Descriptive analyses were used to characterize the sample, assess feasibility outcomes (i.e., attrition rates), and explore symptom-based outcomes across time. Results: Twelve pediatric patients (M age = 15.2 ± 1.7; 91.7% female) and their parents (91.7% mothers) participated. Feasibility metrics based on protocol completion were exceeded for engagement at the stages of consent (68.4% vs. goal of ≥50%), treatment initiation (92.3% vs. 85%), and treatment completion (84.6% vs. 75%). Out of the 12 participants, nine (75%) met criteria for at least one comorbid psychiatric diagnosis at baseline and nine (75%) elected to undergo MALS surgery after completing the intervention. Conclusion: The intervention implementation was feasible, despite chronic pain symptoms experienced by the sample, a high prevalence of psychiatric diagnoses, and an international pandemic, suggesting that it would be beneficial to further evaluate the efficacy of the intervention. Future research should include stakeholder input in the design, deployment, and evaluation of a pilot efficacy trial of pre-surgical cognitive behavioral therapy for pediatric patients with MALS.

The impact of psychiatric comorbidities on patient-reported surgical outcomes in adults treated for the median arcuate ligament syndrome

OBJECTIVE

Median arcuate ligament syndrome (MALS) is an often overlooked, surgically correctable condition that mimics functional chronic abdominal pain. Patient-reported surgical outcomes are unpredictable in MALS. The objective of this study was to define the psychiatric comorbidities in a cohort of adults undergoing surgery for MALS and to determine whether these comorbidities are predictive of patient-reported quality of life (QOL) outcomes.

METHODS

A prospective observational trial was conducted between April 1, 2010, and December 31, 2015, at a single tertiary care hospital. Adults with a diagnosis of chronic abdominal pain in the setting of celiac artery compression were enrolled in a prospective Institutional Review Board-approved observational trial. Patients completed psychological assessments before surgery for MALS and at 6 months after surgery. The primary outcome was patient-reported health-related QOL (young adult version of the Pediatric Quality of Life Inventory).

RESULTS

A total of 51 patients (80% female; n = 41) with a mean age of 30.5 (±12.4) years were enrolled. Surgery significantly improved celiac artery hemodynamics in the entire cohort (P < .0001) as well as overall QOL (67.8 ± 14.6 [before surgery] vs 80.3 ± 13.7 [after surgery]; P < .001). Psychiatric diagnoses were common in this cohort, with 14 of 51 (28%) patients meeting criteria for a psychiatric diagnosis. There were no differences in the number of patients with psychiatric diagnoses between presurgical and postsurgical evaluations (14 [28%] vs 13 [26%]; P = .8). Exploratory analyses suggest that having a psychiatric diagnosis at the presurgical evaluation may predict significantly lower postsurgical QOL (R² = 0.009; P = .01).

CONCLUSIONS

Surgery improves patient-reported QOL in adults treated for MALS. Psychiatric diagnoses are common in adults with MALS and predict worse patient-reported QOL outcomes.

Metachronous Giant Brachial Artery Pseudoaneurysms: A Case Report and Review of the Literature

Brachial artery pseudoaneurysms secondary to intravenous drug abuse represent a limb-threatening problem to patients and a technical challenge to the vascular surgeon. Here information is reported about a patient with metachronous bilateral giant brachial artery pseudoaneurysms secondary to intravenous drug use that were successfully treated with excision of the aneurysm and ligation of the brachial artery. Furthermore, a review of the current literature on the treatment of brachial artery aneurysm is presented.

Relationship Between Preoperative Duplex Vein Mapping and Intraoperative Longitudinal Impedance in Infrainguinal Vein Grafts

The importance of favorable vein size, resistance, and impedance for the sustained success of infrainguinal vein grafting procedures has repeatedly been demonstrated. Estimating these properties preoperatively, however, has been problematic. Ultrasonic vein mapping is a reliable technique for measuring vein diameters at venous pressures, but it is unknown whether these data accurately assess the resistive potential of the conduit in the arterial circulation. The purpose of this study was to compare vein diameter measured preoperatively with vein graft longitudinal impedance measured intraoperatively.

Patients who had undergone both preoperative vein mapping and intraoperative impedance studies at the time of infrainguinal bypass were included (December 1995-April 1999). Vein mapping was performed using B-mode ultrasound with a 10 MHz probe. The dimensions of the specific vein segment used for reconstruction were tabulated and its mean diameter (D̄) was calculated. At the time of operation, following reconstruction, transgraft blood pressure gradient (δP) and blood flow (Q) waveforms were recorded by using digital data acquisition. Longitudinal impedance (ZL) was calculated as δP/Q at each harmonic following Fourier transformation and the area under the curve from 0 to 4 Hz designated as ∫ZL.

Twenty-three bypasses in 22 patients were studied (D̄ = 3.5 ±0.2 mm, range 1.6-5.5 mm; ∫ZL= 37 ±4 x 103 dyne cm-5, range 13-95 X 103 dyne cm-5). D̄ significantly correlated with ∫ZL (slope = -0.454, p < 0.05), albeit with a fairly low correlation coefficient ( r2 = 0.23). D̄ > 3.6 mm was predictive of graft patency at 12 months (D̄ > 3.6 mm 100% vs D̄ < 3.6 mm 57 ±20%; p = 0.02).

Larger veins identified by preoperative mapping have, in general, more favorable intraoperative resistive characteristics as defined by a lower JZL. However, some veins thought to have small diameters (< 3.6 mm) may still demonstrate sufficiently low ∫ZL when grafted to remain patent.

Pediatric Chronic Abdominal Pain and Median Arcuate Ligament Syndrome: A Review and Psychosocial Comparison

Chronic abdominal pain (CAP) occurs in children and adolescents with a reported prevalence of 4% to 41% with significant direct and indirect costs to the child, family, and society. Median arcuate ligament syndrome (MALS) is a vascular compression syndrome of the celiac artery that may cause symptoms of epigastric pain and weight loss and is a frequently overlooked cause of CAP in the pediatric population. We have observed that the psychosocial presentation of patients with MALS is notable for various psychiatric comorbidities. In this article, we review MALS as well as our study results of the psychosocial profile of 30 MALS patients. Our data suggest that children and adolescents with MALS have similar psychosocial profiles to children with other gastrointestinal disorders resulting in CAP. The overlap of physical and psychosocial symptoms of patients who have MALS with other CAP disorders leads us to recommend that patients with CAP should be evaluated for MALS. [Pediatr Ann. 2016;45(7):e257-e264.].

Changes in D-dimer and inflammatory biomarkers before ischemic events in patients with peripheral artery disease: The BRAVO Study

Whether circulating biomarker levels increase shortly before an ischemic heart disease (IHD) event is unknown. We studied whether levels of D-dimer, C-reactive protein (CRP), and serum amyloid A (SAA) are higher within 2 months of an IHD event compared to time periods more than 2 months before the IHD event. We assembled 595 participants with peripheral artery disease (PAD) and followed them for up to 3 years. Blood samples were obtained every 2 months. The primary outcome was IHD events: myocardial infarctions, unstable angina, or IHD death. We used a nested case-control design. Fifty participants (cases) had events and were each matched by age, sex, duration in the study, and number of blood draws to two controls without events. Among cases, the mean D-dimer value of 1.105 obtained within 2 months of the event was higher than values obtained 10 months (0.68 mg/L, p<0.001), 12 months (0.71 mg/L, p=0.001), 16 months (0.65 mg/L, p=0.008), 20 months (p=0.032), 22 months (p=0.033), 26 months (p=0.038), and 32 months (p=0.04) before the event. Compared to controls, median D-dimer levels in cases were higher 4 months (p=0.017), 6 months (p=0.005), and 8 months (p=0.028) before the event. Values of CRP and SAA obtained within two months of an IHD event not consistently higher than values obtained during the prior months. In PAD participants with an IHD event, D-dimer was higher within 2 months of the event, compared to most values obtained 10 to 32 months previously. D-dimer was also higher in cases as compared to controls during most visits within 8 months of the IHD event.

Evidence for the Use of Multiple Mechanisms by Herpes Simplex Virus-1 R7020 to Inhibit Intimal Hyperplasia

Intimal hyperplasia (IH) is the primary cause of vein bypass graft failure. The smooth muscle cell (SMC) is a key element of IH as it phenotypically switches from a contractile to a synthetic state which can become pathological. R7020, which is an engineered strain of Herpes Simplex Virus-1, inhibits IH in animal models. Although it has many characteristics which make it a strong candidate for use as a prophylactic agent how it inhibits IH is not well understood. The objective of this study was to identify modes of action used by R7020 to function in blood vessels that may also contribute to its inhibition of IH. The cytopathic effect of R7020 on SMCs was determined in vitro and in a rabbit IH model. In vitro assays with R7020 infected SMCs were used to quantify the effect of dose on the release kinetics of the virus as well as the effects of R7020 on cell viability and the adhesion of peripheral blood mononuclear cells (PBMCs) to SMCs in the absence and presence of tumor necrosis factor alpha (TNF-α). The observed cytopathic effect, which included R7020 positive filopodia that extend from cell to cell and the formation of syncytia, suggests that R7020 remains cell associated after egress and spreads cell to cell instead of by diffusion through the extracellular fluid. This would allow the virus to rapidly infect vascular cells while evading the immune system. The directionality of the filopodia in vivo suggests that the virus preferentially travels from the media towards the intima targeting SMCs that would lead to IH. The formation of syncytia would inhibit SMC proliferation as incorporated cells are not able to multiply. It was also observed that R7020 induced the fusion of PBMCs with syncytia suggesting the virus may limit the effect of macrophages on IH. Furthermore, R7020 inhibited the proliferative effect of TNF-α, an inflammatory cytokine associated with increased IH. Thus, the results of this study suggest that R7020 inhibits IH through multiple mechanisms.

Abstract 291: Multiple Mechanisms for the Inhibition of Intimal Hyperplasia by Herpes Simplex Virus Strain R7020

Intimal hyperplasia (IH) is the primary cause of vein bypass graft failure. Smooth muscle cells (SMCs) are a key element of IH as they phenotypically switch from a contractile to a synthetic state which may lead to IH. R7020 is an engineered strain of Herpes Simplex Virus-1 which inhibits IH in animal models. Although it has many characteristics which make it a strong candidate for use as a prophylaxis agent how it inhibits IH is not well understood. IH is multifaceted and R7020 infects a wide range of cell types regulating their cellular functions and pathways. Therefore we hypothesized that R7020 inhibits IH by altering multiple cellular functions and cell types. The objective of this study was to identify mechanisms used by R7020 to function in blood vessels that may contribute to its inhibition of IH. In this study the cytopathic effect of R7020 on SMCs was determined in vitro and in a rabbit IH model. The effects of R7020 on SMC viability and the adhesion of peripheral blood mononuclear cells (PBMCs) to SMCs were quantified in the absence and presence of TNF-α. Microarray analysis was used to identify genes whose expression was altered by R7020 in vivo. The cytopathic effects which include filopodia positive for R7020 tegument proteins extending from cell to cell and the formation of syncytia suggest that R7020 remains cell associated after egress and spreads cell to cell instead of by diffusion through the extracellular fluid. The directionality of the filopodia in vivo suggests that the virus preferentially travels from the media towards the intima targeting the SMCs that would lead to IH. The formation of syncytia would also inhibit SMC proliferation as cells that form syncytia do not proliferate. In addition, R7020 induced the fusion of PBMCs with syncytia which may limit the effect of macrophages on IH. Furthermore, R7020 inhibited the proliferative effect of TNF-α, an inflammatory cytokine associated with increased IH. Microarray analysis detected a significant change in the expression of 58 genes in R7020 infected arteries relative to non-infected at 24 h. The encoded proteins are associated with the immune system, cell death, proliferation/motility and vascular tone. Thus this study identifies multiple mechanisms which R7020 may be using to inhibit IH.

Median arcuate ligament syndrome in the pediatric population

OBJECTIVES

Median arcuate ligament syndrome (MALS) is a vascular compression syndrome with symptoms that overlap chronic functional abdominal pain (CFAP). We report our experience treating MALS in a pediatric cohort previously diagnosed with CFAP.

PATIENTS AND METHODS

We prospectively evaluated 46 pediatric (<21years of age) patients diagnosed with MALS at a tertiary care referral center from 2008 to 2012. All patients had previously been diagnosed with CFAP. Patients were evaluated for celiac artery compression by duplex ultrasound and diagnosis was confirmed by computed tomography. Quality of life (QOL) was determined by pre- and postsurgical administration of PedsQL™ questionnaire. The patients underwent laparoscopic release of the median arcuate ligament overlying the celiac artery which included surgical neurolysis. We examined the hemodynamic changes in parameters of the celiac artery and perioperative QOL outcomes to determine correlation.

RESULTS

All patients had studies suggestive of MALS on duplex and computed tomography; 91% (n=42) positive for MALS were females. All patients underwent a technically satisfactory laparoscopic surgical release resulting in a significant improvement in blood flow through the celiac artery. There were no deaths and a total of 9 complications, 8 requiring a secondary procedure; 33 patients were administered QOL surveys. 18 patients completed the survey with 15 (83%) patients reporting overall improvement in the QOL. Overall, 31/46 patients (67%) reported improvement of symptoms since the time of surgery.

CONCLUSIONS

MALS was found to be more common in pediatric females than males. Laparoscopic release of the celiac artery can be performed safely in the pediatric population. Surgical release of the artery and resultant neurolysis resulted in significant improvement in the blood flow, symptoms, and overall QOL in this cohort. The overall improvement in QOL outcome measures after surgery leads us to conclude that MALS might be earlier diagnosed and possibly treated in patients with CFAP. We recommend a multidisciplinary team approach to care for these complex patients.

Contemporary outcomes in vascular patients who require preoperative coronary stent

BACKGROUND

The documented risks of preoperative coronary revascularization prior to vascular surgery have led to a marked reduction in the role of percutaneous coronary intervention (PCI) during preoperative risk stratification. However, many patients with peripheral arterial disease are first identified immediately after a PCI for an acute coronary syndrome. We sought to determine the risks associated with these patients who then go on to have a peripheral arterial intervention (open operation or endovascular procedure). We hypothesized that there was no difference in outcomes in patients whose medical condition required PCI with coronary stent placement prior to a vascular operation compared with a control cohort of nonstented patients who underwent a vascular operation alone. We report the vascular operative outcomes in a contemporary cohort of vascular patients who had PCI with coronary stent placement for an acute event.

METHODS

We performed a retrospective cohort analysis, utilizing administrative data, of 3,678 vascular patients from 2005 to 2010 at a tertiary care hospital. Two groups were defined: patients with preoperative PCI and coronary stent placement within 1 year prior to vascular operation (N = 101, mean age 66 ± 1.22 years, 51.5% men); and patients with no PCI prior to vascular operation (N = 3,577, mean age 60 ± 0.27 years, 46.37% men). Cardiovascular risk factors and complications derived from ICD-9 codes were used to parse data after open peripheral vascular surgery, endovascular repair, or amputation. Primary outcomes were death, nonfatal myocardial infarction, major adverse cardiac event (MACE, defined as death, myocardial infarction, or subsequent coronary revascularization) or bleeding.

RESULTS

Univariate analysis showed significant differences in both demographic and outcome analysis in patients with and without prior coronary stent. Patients with a recent PCI followed by a vascular procedure were more likely to undergo an endovascular procedure (75.3% vs. 64.5%, odds ratio = 1.67, P = 0.028). These patients also had 11 of 20 cardiovascular risk factors, significantly higher than in those without a prior PCI. Multivariate subgroup analysis indicated that patients with a prior coronary stent were more likely to have an episode of congestive heart failure (CHF) after 1 year of surgery (16.8%, P = 0.045). In addition, an acute cardiac ischemic event was more likely within 1 year (2.0%, P = 0.036) and beyond 1 year (4.0%, P = 0.022) of surgery. Importantly, there was no significant increase in death, myocardial infarction, MACE, or bleeding in patients with a preoperative coronary stent.

CONCLUSIONS

Patients who underwent PCI with coronary stent and then went on to require a vascular procedure had significantly more cardiovascular (CV) risk factors and were more likely to have an endovascular procedure than those patients without preoperative PCI. When controlling for CV risk factors and procedure type, there was no significant difference in death, MI, MACE, or bleeding complications between the groups.

Abstract 196: Effects of an Engineered Herpes Simplex Virus (HSV-1) on Vascular Cell Adhesion

Introduction

The genetically engineered HSV R7020 is known to block vascular smooth muscle cell (SMC) proliferation while allowing for re-endothelialization after balloon angioplasty. This HSV-1 anti-proliferative effect requires MEK activation. However, it is unknown what effect R7020 has on vascular inflammation and monocyte adhesion. We hypothesized that exposure of SMCs to HSV R7020 would not affect vascular adhesion molecules.

Methods

Human aortic SMCs were exposed to R7020 for 10 minutes in the absence and presence of TNF-α (10 ng/ml). After washing cells were cultured for 24 hours in the absence and presence of TNF-α. Vascular cell adhesion molecule 1 (VCAM-1) and intracellular adhesion molecue-1 (ICAM-1) levels were determined using immunocytochemistry and image J. The adhesion of calcein AM labeled PBMCs to these cells were also analyzed at 24 hours. VCAM-1 and ICAM-1 levels were measured in the carotids of New Zealand White Rabbits that underwent balloon injury and exposed to R7020 (n=4) or saline (n=4) for 10 minutes using microarray analysis.

Results

There was no significant difference in ICAM-1 levels in the R7020 treated and control SMCs (219±11 vs 223±1; p=0.758); there was an 8 fold increase in ICAM-1 in the TNF-α treated SMCs (219±11 vs 1587±68; p=1.2x10 -13 ). Results were similar for VCAM-1. R7020 caused an increase in the adhesion strength of SMCs to collagen coated glass slides at 24 hours. Microscopic experiments (n=3) showed PBMCs adhered similarly to SMCs treated with TNF-α in the absence and presence of the virus (4 times that of control cells as measured by PBMC adhesion assay). Interestingly, after adhesion, Calcein AM was frequently observed in virus infected SMCs in the presence and absence of TNF-α. In cells not exposed to R7020, this rarely occurred. Microarray analysis demonstrated a 2.3 fold reduction in VCAM-1 expression in the R7020 treated rabbits (p=2.8x10 -14 ) and no significant difference in expression in ICAM gene expression (p=0.3).

Conclusions

In contrast to TNF-α, R7020 does not increase ICAM-1 or VCAM-1. Both treatments domonstrate PBMC SMC adhesion with no additive or synergistic effect. However, R7020 results in intracellular transfer from PBMCs to SMCs suggesting the virus changes PBMC-SMC interplay.

Abstract 566: The Transcriptome of the Human Carotid Atherosclerotic Plaque

Ischemic stroke is a complex disease process with carotid atherosclerosis as the major etiologic source. To better understand the biology of a vulnerable plaque we carried out whole transcriptome shotgun sequencing of human carotid plaques.

Methods

5 carotid atherosclerotic plaques were obtained at the time of operation (2 symptomatic, 2 asymptomatic, and 1 control). RNA was isolated and 5 cDNA libraries were constructed and sequenced with single-reads100nt in length using one line of flow cell of HySeq 2000 (Illumina Inc). Standard bioinformatic techniques were used to ensure quality screening of raw reads. Ingenuity Systems IPA software was used to determine canonical biological pathways overrepresented in plaques. We compared our data to the data of Illumina Human Body Map processed by a similar analytical pipeline. Linkage analysis was performed.

Results

Among detected pathways were “Atherosclerosis Signaling” and pathways involved in inflammation and cell differentiation. We analyzed gene expression data by creating a distance matrix based on Jaccard similarity measure (Fig 1). When gene expression values were used to create a matrix of Euclidian distances between known transcriptomes, four specimens including the control clustered with heart and muscle. The transcriptome from the stroke patient was more similar to lung, liver and heart.

Conclusion

Whole transcriptome analysis of carotid plaques is feasible and ontologically accurate. We demonstrate linkage differences between symptomatic and asymptomatic plaques and biological pathways involved in vascular lesion formation. Further analysis may provide insight into the vulnerable plaque pathobiology.

Modulating vascular intimal hyperplasia using HSV-1 mutant requires activated MEK

Outcomes of cardiovascular procedures, such as angioplasty and stent or bypass grafting are limited by failure, predominantly caused by pathological smooth muscle cell (SMC) proliferation, known as intimal hyperplasia. Local delivery of a genetically engineered herpes simplex virus (HSV) is known to block vascular SMC proliferation while allowing for re-endothelialization. However, the mechanism this mutant virus uses to prevent SMC hyperplasia is unknown. The Ras signaling cascade is activated in SMCs undergoing hyperplasia leading to phosphorylation of the mitogen-activated protein kinase (MAPK). In this study we tested the hypothesis that MAPK kinase (MEK) activity is the molecular basis by which SMCs are susceptible to mutant HSV. We show that genetically engineered herpes simplex-1 viruses (HSV-1) can target proliferating SMCs. We demonstrate that the molecular basis of this HSV-1 anti-proliferative effect is MEK activation in SMCs. We demonstrate efficacy and practicality of the MEK-dependent HSV-1 for the treatment of intimal hyperplasia in a clinically relevant in vivo model. Important to this strategy is the ability to modulate the effects by controlling viral dose. These results propel genetically engineered HSV-1 therapy towards clinical evaluation in treatment of intimal hyperplasia.

Evaluation and treatment of suspected type II endoleaks in patients with enlarging abdominal aortic aneurysms

PURPOSE

To evaluate angiographic diagnosis and embolotherapy of patients with enlarging abdominal aortic aneurysms and computed tomographic (CT) diagnosis of type II endoleak.

MATERIALS AND METHODS

A retrospective review was performed of all patients referred to a single vascular and interventional radiology section from January 1, 2003, to June 1, 2011, with a diagnosis of enlarging aneurysm and type II endoleak. Twenty-five patients underwent 40 procedures between 12 and 82 months after endograft insertion (mean, 48 mo) for diagnosis and/or treatment of endoleaks.

RESULTS

Type II endoleaks were treated with cyanoacrylate, coils, and ethylene vinyl alcohol copolymer in 16 patients. Technical success rate was 88% (14 of 16 patients) and clinical success rate was 100% (16 of 16 patients). Aneurysm growth was arrested in all cases over a mean follow-up of 27.5 months (range, 6-88 mo). Endoleaks in nine patients were misclassified on CT; two had type I endoleaks and seven had type III endoleaks. Four of the nine patients (two type I endoleaks and two type III endoleaks) were correctly classified after initial angiography. The other five type III endoleaks were correctly classified on CT after coil embolization of the inferior mesenteric artery. Direct embolization was performed via sac puncture with ethylene vinyl alcohol copolymer in two of the latter five patients and eliminated endoleaks in both.

CONCLUSIONS

Aneurysm growth caused by type II endoleaks was arrested by embolization. CT misclassification occurred relatively commonly; type III endoleaks purported to be type II endoleaks were found in 28% of patients (seven of 25).

Eureka!!! Sewing to Moonbeams

A thermoreversible nanopolymer enables a new method of creating sutureless vascular-vascular connections without trauma to the tissue.

Healing Achilles’ Heel

Self-assembling filamentous peptide nanofibers promote therapeutic angiogenesis.

Setting Sights on a Silent Killer

Improved optical imaging technology moves 3D histology and electron microscopy in vivo.

Home Is Where the Heart Is

Scientists discover a resident progenitor cell population that can terminally differentiate into cardiac muscle cells after heart attack.

Construction–Deconstruction–Reconstruction

Tissue-engineered allogeneic blood vessels have potential in cardiac bypass surgery.

Balloons with Brains

Semiconductor devices and sensors integrated into biocompatible materials transform balloon catheters into a next-generation surgical tool.

PEG Gets to the Heart of the Matter

Polyethylene glycol improves cardiac function by inhibiting the apoptotic pathway induced by ischemia-reperfusion injury.

These Peptides Have Got a Lot of Nerve

Short, fluorescently labeled peptides could allow for better visualization of peripheral nerves during surgery.

Concomitant proliferation and caspase-3 mediated apoptosis in response to low shear stress and balloon injury

BACKGROUND

Arterial remodeling occurs as a response to hemodynamic change and direct vessel wall injury through the process of neointimal hyperplasia (NH). A concomitant response of vascular smooth muscle cell (VSMC) proliferation and apoptosis exists. The purpose of this study is to assess the cellular response of vessels following exposure to low shear stress (tau) and balloon injury in order to further elucidate the mechanisms underlying vascular injury. Our hypothesis is that the combination of low tau and balloon injury results in NH approximating that seen in clinical arterial restenosis, and that quantitative analysis of VSMC proliferation and apoptosis correlates with the associated increase in arterial remodeling.

METHODS AND RESULTS

New Zealand White rabbits underwent surgery on the carotid artery creating low tau (n =11), balloon injury (n = 11), combined low tau and balloon injury (n =11), and sham (n = 13) groups. Experiments were terminated at 1, 3, and 28 d. Day 1 and 3 arteries were analyzed with immunohistochemistry for apoptotic markers, terminal transferase dUTP nick end labeling (TUNEL), and activated caspase-3, and a cellular proliferation marker, accumulated proliferating cell nuclear antigen (PCNA), as well as immunoblot analysis for activated caspase-3 and PCNA at day 3. There was significantly greater apoptosis in the combined group as compared with the other groups assessed by quantitative TUNEL and activated caspase-3 levels at both days 1 and 3. Similarly, an increase in cellular proliferation assessed by PCNA expression, was significantly greater in the combined group as compared with the other groups. At 28 d there was no difference in NH observed in the low tau (26 +/- 3 microm) and balloon injury (51 +/- 17 microm) groups. However, significantly more NH was observed in the combined group (151 +/- 35 microm) as compared with the other groups.

CONCLUSIONS

An increase in VSMC apoptosis via a caspase-3 dependent pathway is up-regulated by 24 h in the face of combined low shear stress and balloon-induced vessel wall injury. Paradoxically, this increase in VSMC apoptosis is associated with a significant increase in neointimal thickening at 28 d. The concomitant increase of both apoptosis and proliferation are indicative of a robust arterial remodeling response.

Use of internal endoconduits as an adjunct to endovascular aneurysm repair in the setting of challenging aortoiliac anatomy

The combination of Trans-Atlantic Intersociety Consensus (TASC) D aortoiliac occlusive disease as well as a symptomatic abdominal aortic aneurysm (AAA) is not a common occurrence. Extensive calcified atherosclerotic disease, occlusions, and small iliofemoral segmental arteries make transfemoral access difficult, if not impossible, for endovascular aneurysm repair (EVAR) in these patients. We present a case in which "controlled rupture" of the external iliac artery with a covered stent allowed transfemoral delivery of an aortouni-iliac stent graft with a completion femoral-to-femoral bypass. The patient is a 60-year-old male with a 5.3 cm symptomatic infrarenal AAA and a history of one block right leg claudication. Preoperative computed tomography angiography revealed the patient to have occlusion of the right common iliac artery, extensive calcified stenoses of his aortoiliac segments, and a prohibitively small left external iliac artery, which measured 4.5 mm at its narrowest diameter. The patient, despite discussions concerning the suitability of his iliac arteries as conduits for the delivery of the stent graft, insisted on an endovascular approach to lessen his chances of postoperative sexual dysfunction as well as minimize his length of stay. Access was obtained through bilateral femoral artery cutdowns, and attempts at dilating the left external iliac artery using 16-French dilators were performed without success. An 8 mm x 5 cm covered self-expanding stent was deployed in the diseased 4.5 mm left external iliac artery, followed by angioplasty performed with an 8 mm noncompliant balloon to disrupt the vessel. This endoconduit now allowed accommodation of our 18-French introducer for the aortouni-iliac stent graft. The operation was completed with a femoral-femoral bypass. Flow to both hypogastric arteries was preserved. We believe use of such techniques will ultimately expand the number of patients eligible for EVAR and avoid devastating access-related complications.

Is atherectomy the best first-line therapy for limb salvage in patients with critical limb ischemia?

OBJECTIVE

To determine the efficacy of atherectomy for limb salvage compared with open bypass in patients with critical limb ischemia.

METHODS

Ninety-nine consecutive bypass and atherectomy procedures performed for critical limb ischemia between January 2003 and October 2006 were reviewed.

RESULTS

A total of 99 cases involving TASC C (n = 43, 44%) and D (n = 56, 56%) lesions were treated with surgical bypass in 59 patients and atherectomy in 33 patients. Bypass and atherectomy achieved similar 1-year primary patency (64% vs 63%; P = .2). However, the 1-year limb salvage rate was greater in the bypass group (87% vs 69%; P = .004). In the tissue loss subgroup, there was a greater limb salvage rate for bypass patients versus atherectomy (79% vs 60%; P = .04).

CONCLUSIONS

Patients with critical limb ischemia may do better with open bypass compared with atherectomy as first-line therapy for limb salvage.

Attenuated herpes simplex virus 1 blocks arterial apoptosis and intimal hyperplasia induced by balloon angioplasty and reduced blood flow

Injury caused by distention of the arterial wall by balloon angioplasty can result in apoptosis and vascular smooth muscle cell proliferation. Here, we report that a brief exposure of the arterial lumen to a genetically engineered, attenuated herpes simplex virus 1 blocks activation of caspase 3-dependent apoptosis and MAPK-dependent cell proliferation induced by carotid artery balloon angioplasty and ligation to reduce blood flow. The procedure enables the restoration of the endothelial cell layer lining the lumen and prevents neointimal hyperplasia and restenosis. These findings have a broad application in prevention of balloon angioplasty-induced restenosis.

Differential effects of carotid artery stenting versus carotid endarterectomy on external carotid artery patency

PURPOSE

To determine the effect of stent coverage of the external carotid artery (ECA) after carotid artery stenting (CAS) compared to eversion endarterectomy of the ECA after carotid endarterectomy (CEA).

METHODS

The records of 101 CAS and 165 CEA procedures performed over 2 years were reviewed. Duplex velocities and history and physical examinations were taken prior to the procedure, at 1 month, and at 6-month intervals subsequently. CAS was performed by extending the stent across the internal carotid artery (ICA) lesion into the common carotid artery (CCA) thereby covering the ECA. CEA was performed with eversion endarterectomy of the ECA.

RESULTS

The mean peak systolic velocities (PSV) in the ICA pre-CAS and pre-CEA were 361 and 352 cm/s, respectively. In terms of CAS, there was a significant increase in ECA velocities versus baseline at 12 (p = 0.009), 18 (p = 0.00001), and 24 (p = 0.005) months. In the CEA group, there was a significant decrease in ECA velocities versus baseline at 1 (p = 0.01) and 6 (p = 0.004) months. There were 2 occluded ECAs in follow-up in the CAS group and none in the CEA group. No significant differences were noted when comparing preprocedural ICA or ECA velocities. However, at the 1-, 6-, and 12-month intervals, the ECA velocities in the CAS group were significantly higher than in the CEA group (p = 0.03, p = 0.001, and p = 0.0004, respectively). There were no neurological symptoms in any patients during the study period.

CONCLUSION

Although progressive stenosis of the ECA is noted during CAS, the ECA usually does not occlude. Furthermore, there are no associated neurological symptoms. Thus, apprehension for progressive ECA occlusion should not be a contraindication to CAS. In addition, concern for ECA coverage should not deter stent extension from the ICA to the CCA during CAS.

Risk factors for restenosis after carotid artery angioplasty and stenting

OBJECTIVES

With carotid artery stenting (CAS) becoming an ever-increasing procedure, we sought to determine risk factors for in-stent restenosis after CAS.

METHODS

Consecutive patients undergoing CAS between January 2002 and October 2004 at a tertiary care hospital were retrospectively reviewed. Patient, filter, and stent selection were left to the discretion of the attending surgeon. High-risk patients were defined by significant comorbidities or a hostile neck (prior surgery or radiation, or both), and risk factor analysis was performed. In-stent restenosis was defined as >60%, and selective angiography was performed on patients with an in-stent restenosis >80% by duplex ultrasound imaging.

RESULTS

Reviewed were 101 patients (55 men, 46 women) who underwent 109 CAS procedures. Comorbidities were typical for patients with atherosclerosis. In addition, 38% (n = 41) of procedures were performed in patients who had prior neck surgery, of which 29% (n = 32) had previous ipsilateral carotid endarterectomy. Seventeen patients (16%) had a history of neck cancer, and all had prior neck radiation. Median follow-up was 5 months (range, 0 to 30 months). Neurologic complications included three transient ischemic attacks (2.8%) and one nondisabling stroke (0.9%). There were two myocardial infarctions (1.9%) and no periprocedural deaths (30 days), for a combined stroke, myocardial infarction, and death rate of 2.9%. Asymptomatic in-stent restenosis developed in 12 carotids (11%), five of which required endovascular intervention, with a mean of 6 months to restenosis. Univariate Cox proportional hazard regression models were used to determine risk factors for the development of restenosis. Prior stroke, transient ischemic attack, amaurosis fugax, and prior neck cancer were all significant risk factors. When these significant risk factors from univariate analysis were put into multivariate analysis, however, the only marginally significant risk factor was prior neck cancer (P = .06). Kaplan-Meier analysis revealed a cumulative freedom from in-stent restenosis at 24 months of 88% +/- 6% in patients without neck cancer compared with 27% +/- 17% (P = .02) in patients with neck cancer.

CONCLUSIONS

CAS has been shown to be safe and effective in high-risk patients, with minimal adverse events.

Ruptured popliteal artery aneurysm: a case report

A high index of suspicion for popliteal aneurysms must be present when evaluating a popliteal mass. Though typically pulsatile, in the presence of chronic thrombosis, the absence of a pulse may make the diagnosis even more difficult. A case is presented that illustrates this point, where an 83-year-old man presents following the biopsy of what turned out to be a very large popliteal aneurysm. In the presence of chronic thrombosis and adequate collateral flow, decompression and ligation of any feeding vessels is typically sufficient. These patients must be followed lifelong for the development of other associated aneurysms.

Emergency Endovascular Deployment of Stent Graft in the Ascending Aorta for Contained Rupture of Innominate Artery Pseudoaneurysm in a Pediatric Patient

Endovascular approaches to treat aortic diseases have become an important alternative to open surgical intervention in aortic pathologies. We report a case of an emergency placement of a stent graft in a 16-year-old boy with a contained rupture of an innominate artery pseudoaneurysm. This patient had been previously treated for a mediastinal T-cell lymphoma and underwent mediastinal chemoradiation. He developed tracheal stenosis, requiring multiple tracheal reconstructive surgical procedures, and subsequently emergency ligation of a tracheal-innominate fistula. A pseudoaneurysm of the previously ligated innominate artery developed. Despite coil embolization, it continued to enlarge, requiring emergency endovascular intervention. A pseudoaneurysm of the previously ligated innominate artery subsequently developed, and despite coil embolization, it continued to enlarge, which required emergency endovascular intervention.

Modulation of vascular remodeling induced by a brief intraluminal exposure to the recombinant R7020 strain of Herpes simplex-1

OBJECTIVE

Vascular remodeling in response to injury or low shear stress (or both) is characterized by neointimal hyperplasia and luminal contraction. When profound, the response leads to restenosis after percutaneous endovascular intervention as well as to de novo stenosis in vein grafts. It has recently been reported that exposure of vein patches to neurovirulence-attenuated Herpes simplex virus-1 (HSV-1) decreases neointimal hyperplasia and increases luminal area. This experiment tested the hypothesis that R7020, a more highly attenuated mutant of HSV-1, would modulate the vascular remodeling response of experimental vein grafts chronically exposed to low shear stress.

METHODS

The external jugular veins of 31 New Zealand white rabbits were clamped and intraluminally exposed to vehicle (phospate-buffered saline solution, n = 11), R7020 2.5 x 10(8) plaque forming units [PFU]/mL (n = 8), or R7020 2.5 x 10(9) PFU/mL (n = 12) for 10 or 30 minutes at an average pressure of 80 mm Hg. After exposure, an end-to-side distal external jugular-to-common carotid artery anastomosis was created, resulting in a widely patent arteriovenous fistula. The external jugular was suture-ligated just proximal to the thoracic inlet, distal to a small 10- to 50-microm venous tributary, creating a reversed vein "graft" segment immediately and abruptly exposed to arterial pressure (48 +/- 3 mm Hg) and low shear stress (0.12 +/- .02 dyne/cm(2)). In the 29 animals (N = 31) that survived to harvest, 26 grafts were found to be patent and were analyzed further. Nine grafts were harvested within the first week after operation, snap frozen in liquid nitrogen, and assayed for the presence of the Herpes viral immediate-response protein ICP0 by Western blot analysis. The 17 remaining grafts were perfusion-fixed, excised, stained, and analyzed morphometrically by digital planimetry.

RESULTS

In patent grafts, the hemodynamic environment of low shear stress was maintained (shear stress at harvest, 0.26 +/- .06 dyne/cm(2)). Western blot analysis revealed the presence of ICP0 in R7020-exposed vein grafts after 2, 3, 7, and 14 days; ICP0 was not detected in unexposed vein grafts or adjacent carotid arteries. After 4 weeks, vein grafts exposed to R7020 exhibited a statistically significantly increased ratio of luminal radius to wall thickness, indicating altered remodeling (vehicle, 6.7 +/- 1.3; R7020 2.5 x 10(8), 9.1 +/- 1.3; R7020 2.5 x 10(9) ratio, 11.3 +/- 1.4; P < .05 for high dose compared with vehicle).

CONCLUSION

A brief exposure of the neurovirulence-attenuated HSV-1 strain R7020 results in an increased ratio of luminal radius to wall thickness in experimental vein grafts chronically exposed to low shear stress.

Thoracoscopic Thymectomy in Children with Myasthenia Gravis

Although conservative medical management is the mainstay in the treatment of myasthenia gravis (MG), severest forms of the disease often require surgical thymectomy. Thoracoscopic thymectomy (TT) represents a minimally invasive alternative to traditional thymectomy via sternotomy. We present our preliminary experience with TT as definitive treatment for severe forms of MG. The charts of 5 children (4 girls and 1 boy; age range, 11-17 years) who underwent TT for MG were retrospectively reviewed. TT was typically performed via left thoracoscopy using 4- or 5-mm ports with 1 of the ports enlarged at the end of the procedure for specimen retrieval. Thymic veins were identified and ligated with surgical clips in all cases. Surgical parameters assessed were the following: operating time, intra- and postoperative complications, length of postoperative stay, and resolution of symptoms. Follow-up ranged from 6 months to 2 years. All 5 TTs were successfully completed. In 1 case, right-sided thoracoscopy was added to ensure complete gland excision. Surgical pathology in all cases demonstrated complete excision. Mean operating time was 121 minutes (range 88 minutes to 188 minutes). There were no intra- or postoperative complications. Length of postoperative stay averaged 1.6 days (range, 1 to 3 days). Four of 5 (80%) had clear resolution of symptoms with 1 showing minimal resolution at 6 months. Thoracoscopic thymectomy is a safe and potentially attractive alternative to traditional thymectomy via median sternotomy in severe forms of myasthenia gravis. Complete thymectomy, the goal of traditional surgical treatment for myasthenia gravis, can effectively by achieved via this minimally invasive technique.

Thoracoscopic thymectomy in children with myasthenia gravis

Although conservative medical management is the mainstay in the treatment of myasthenia gravis (MG), severest forms of the disease often require surgical thymectomy. Thoracoscopic thymectomy (TT) represents a minimally invasive alternative to traditional thymectomy via sternotomy. We present our preliminary experience with TT as definitive treatment for severe forms of MG. The charts of 5 children (4 girls and 1 boy; age range, 11-17 years) who underwent TT for MG were retrospectively reviewed. TT was typically performed via left thoracoscopy using 4- or 5-mm ports with 1 of the ports enlarged at the end of the procedure for specimen retrieval. Thymic veins were identified and ligated with surgical clips in all cases. Surgical parameters assessed were the following: operating time, intra- and postoperative complications, length of postoperative stay, and resolution of symptoms. Follow-up ranged from 6 months to 2 years. All 5 TTs were successfully completed. In 1 case, right-sided thoracoscopy was added to ensure complete gland excision. Surgical pathology in all cases demonstrated complete excision. Mean operating time was 121 minutes (range 88 minutes to 188 minutes). There were no intra- or postoperative complications. Length of postoperative stay averaged 1.6 days (range, 1 to 3 days). Four of 5 (80%) had clear resolution of symptoms with 1 showing minimal resolution at 6 months. Thoracoscopic thymectomy is a safe and potentially attractive alternative to traditional thymectomy via median sternotomy in severe forms of myasthenia gravis. Complete thymectomy, the goal of traditional surgical treatment for myasthenia gravis, can effectively by achieved via this minimally invasive technique.

Redo infrainguinal bypass: factors predicting patency and limb salvage

The increased complexity of redo infrainguinal bypass procedures can result in prolonged operative time and increased morbidity. This review was undertaken to compare outcomes from primary and redo bypass procedures and to identify factors predictive of graft failure and limb loss after redo bypass. All infrainguinal bypasses ( n = 468) from 1995 to 1999 were reviewed. A total of 367 primary bypasses in 317 patients were compared to 101 redo grafts in 84 patients with previously failed bypasses. Risk factors and types of procedures were compared using Student's t-test and the chi(2) test. Patency and limb salvage were compared using life-table analysis. Patients requiring redo bypasses were less likely to have diabetes and end-stage renal disease. Two-year patency (66 +/- 4% primary vs. 55 +/- 7% redo, p = 0.13) and limb salvage (75 +/- 3% primary vs. 72 +/- 6% secondary, p = 0.43) were comparable between primary and redo bypass groups. Female gender was predictive of redo graft failure (2-year patency 73 +/- 8% male vs. 39 +/- 9% female, p = 0.01). Clinical indications that predicted failure of a redo bypass included thrombosis of an autologous graft (1-year patency 71 +/- 7% previous prosthetic vs. 49 +/- 10% previous autologous, p = 0.004), thrombosis of an infrageniculate bypass (2-year patency 65 +/- 10% suprageniculate vs. 46 +/- 9% infrageniculate, p = 0.044), and a limb salvage indication for the primary operation (2-year patency 86 +/- 9% claudication vs. 44 +/- 8% limb salvage, p = 0.008). When a primary bypass fails despite the use of optimal conduit (autologous vein) and an infrageniculate target vessel, the redo bypass has a higher risk of failure, particularly in female patients. Nonetheless, patency and limb salvage rates justify an attempt at revascularization after failed primary bypass.

Sustained inhibition of experimental neointimal hyperplasia with a genetically modified herpes simplex virus

OBJECTIVE

Reported herein is a potential strategy for sustained smooth muscle cell (SMC) inhibition with a virulence-attenuated herpes simplex virus (HSV). Experiments were conducted in vitro to demonstrate selective SMC cytotoxicity and in vivo to demonstrate reduced neointimal hyperplasia (NIH) in a clinically relevant animal model.

METHODS

In vitro: Cultured human umbilical artery smooth muscle cells (UASMC) and venous endothelial cells (HUVEC) were exposed to varying multiplicities of infection (MOI) of a gamma(1)34.5-deleted HSV-1 virus (R849). Cell survival was assessed at 48 and 72 hours with a colorimetric MTT viability assay. In vivo: New Zealand White rabbit external jugular veins (n = 21) were exposed to R849 (2.5 x 10(6) pfu/mL) or culture medium at 110 to 120 mm Hg for 10 minutes, then fashioned as vein patches on carotid arteries. Carotid arteries were ligated distally to decrease blood flow and stimulate a hyperplastic response (ultra-low shear stress model). After 2, 4, 12, and 24 weeks, patched segments were perfusion-fixed with glutaraldehyde and morphometrically examined for NIH formation.

RESULTS

In vitro: At 48 hours, R849 exhibited preferential cytotoxicity to UASMC compared with HUVEC, with 11% +/- 10% of UASMCs and 49% +/- 8% of HUVECs surviving after infection with MOI = 25 (P <.05). Higher MOI resulted in poor survival of both cell lines. In vivo: Blood flow was similarly reduced in all animals both at surgery (0.9 +/- 0.1 mL/min vs 1.6 +/- 0.3 mL/min) and at harvest (2.7 +/- 0.4 mL/min vs 2.5 +/- 0.5 mL/min). R849-infected patches exhibited markedly less NIH than control patches did at 2 weeks (162 +/- 14 microm vs 49 +/- 6 microm; P <.05), 4 weeks (190 +/- 27 microm vs 67 +/- 8 microm; P <.05), and 12 weeks (233 +/- 18 microm vs 113 +/- 2 microm; P <.05).

CONCLUSION

The virulence-attenuated HSV strain R849 demonstrates selective cytotoxicity for SMC and is capable of sustained inhibition of NIH in an experimental model of vein graft failure.

Long-term outcome of infrainguinal bypass grafting in patients with serologically proven hypercoagulability

OBJECTIVE

The purpose of this study was to test the hypothesis that the long-term outcome of infrainguinal bypass grafting in patients with congenital or acquired hypercoagulability is inferior to the results in patients without documented clotting disorders.

METHODS

The study was a retrospective analysis of consecutive patients from January 1994 to January 2001.

RESULTS

Five hundred eighty-two infrainguinal bypass grafts were created in 456 patients. Indication for surgery was limb-threatening ischemia in 84%; prosthetic conduits were implanted in 38%. Seventy-four grafts were created in 57 patients with one or more serologically proven hypercoagulable states, including heparin-induced platelet aggregation (n = 37), anticardiolipin antibodies (n = 11), lupus anticoagulant (n = 8), protein C or S deficiency (n = 7), antithrombin III deficiency (n = 3), and factor V Leiden mutation (n = 1). Patients with hypercoagulability were younger (63 +/- 2 years versus 69 +/- 1 years; P =.007), more likely to have undergone prior revascularization attempts (38% versus 21%; P =.003), and more likely to have chronic anticoagulation therapy after surgery (46% versus 25%; P =.001). After 5 years (median follow-up, 19 months), patients with hypercoagulability had poorer primary patency (28% +/- 7% versus 35% +/- 5%; P =.004), primary assisted patency (37% +/- 7% versus 45% +/- 6%; P =.0001), secondary patency (41% +/- 7% versus 53% +/- 6%; P =.0001), limb salvage (55% +/- 8% versus 67% +/- 6%; P =.009), and survival (61% +/- 8% versus 74% +/- 4%; P =.02) rates. Multivariate analysis identified only prosthetic conduit choice (P =.0001), hypercoagulability (P =.0003), and limb salvage indication (P =.01) as independent predictors of graft failure.

CONCLUSION

Patients with serologically proven hypercoagulability have inferior long-term patency, limb salvage, and survival rates after infrainguinal bypass. The high prevalence rate (13%) of diverse hypercoagulable states in this patient population supports serologic screening, especially in referral practices.

Diurnal heart rate reactivity: a predictor of severity of experimental coronary and carotid atherosclerosis

BACKGROUND

Elevated awake resting heart rate (HR) has been shown to be a major risk factor for cardiovascular disease. Since coronary ischaemic events appear to peak during transition from sleep to awake HR, we sought to determine whether the degree of diurnal HR fluctuation (dHRV) is an independent predictor of coronary and peripheral atherogenesis. In this study, we varied both baseline HR and dHRV using sino-atrial node ablation (SNA) in a primate model of diet-induced atherogenesis and determined the degree of plaque formation relative to both HR parameters.

METHODS

HR was recorded continuously for 6 months by an implantable intraaortic sensor/transmitter in 17 active unrestricted male cynomolgus monkeys. In nine monkeys, SNA was employed to create a wide spectrum of dHRV, and the power amplitude of dHRV was determined for the daily HRV cycle with power spectral analysis. After a 6-month diet induction period, percent coronary and carotid stenosis, intimal thickness and area were quantitated in each animal.

RESULTS

Total serum cholesterol and mean HR were no different between high ( n= 10) and low ( n= 7) dHRV groups (866 mg% vs. 740 mg%, P> 0.2 and 130 +/- 22 and 115 +/- 13, P> 0.1, respectively). Percent carotid stenosis was markedly greater in both high HR and dHRV animals ([HR], 54 +/- 19 vs. 35 +/- 10, P< 0.04) and ([dHRV], 54 +/- 17 vs. 32 +/- 10, P< 0.01). Significant increases in all measures of coronary atherogenesis were found in high dHRV animals when compared with those with low dHRV (percent stenosis: 48% +/- 22 vs. 23% +/- 16, P< 0.02), (lesion area: 1.2 +/- 0.8 vs. 0.3 +/- 0.3, P< 0.02), and (intimal thickness: 0.3 +/- 0.1 vs. 0.1 +/- 0.1, P< 0.01), respectively. While there was a trend towards greater coronary atherogenesis in animals with high HR, this did not reach statistical significance.

CONCLUSION

Elevated HR and dHRV are both associated with enhanced experimental atherosclerotic plaque formation. However, a greater degree of carotid and coronary atherogenesis is observed in animals with high dHRV. These findings suggest that elevated dHRV is a stronger predictor for susceptibility to atherogenesis than elevated HR alone. Such a relationship may be attributed to the potential role of dHRV in modulating the frequency of adverse near wall haemodynamic forces, which have been shown to induce atherosclerotic plaques. Lowering of dHRV in humans by exercise or pharmacological agents may have a beneficial role in retarding atherosclerotic plaque induction, progression and complication.

Longitudinal impedance is independent of outflow resistance

BACKGROUND

Many investigators have measured outflow resistance (R) following peripheral bypass procedures, but correlations with graft patency have been weak. This is because the primary determinants of graft patency are the size and quality of the conduit, not its outflow bed. Efforts at separating conduit resistance from outflow resistance have been unsuccessful. Recently, the concept of longitudinal impedance ( integral Z(L)) has been suggested as a measure of conduit resistance independent of outflow resistance. The purpose of this in vitro experiment was to test the hypothesis that integral Z(L) is independent of R within physiologically relevant ranges.

METHODS

Rigid polyethylene tubing of known internal diameter and length (4.3 mm, 375 cm) was perfused with a glycerin/saline mixture mimicking the viscosity of blood (4.1 cp), utilizing a variable pulsatile pump and Windkessel, with outflow into multiply branched tubes of decreasing diameter simulating the hemodynamic conditions of arterial bypass. Flow and pressure were measured using ultrasonic transit time and catheter transduction, respectively, and waveforms digitized at 200 Hz. Flow was varied while maintaining "systemic" pressure and resistance. After Fourier transformation, integral Z(L) was calculated as deltaP/Q at each harmonic and integrated over 4 Hz.

RESULTS

integral Z(L) calculations were remarkably reproducible within the same day with a coefficient of variation (CV) = 4.0% (at 100 dyne. s/cm(5); n = 4) or over 4 successive days (CV = 4.3%). Furthermore, integral Z(L) was largely independent of R over the physiologic range tested, with integral Z(L) remaining relatively constant as R was increased sixfold.

CONCLUSION

integral Z(L) is a consistent and reproducible measure of conduit resistance independent of R over a wide physiologic range. It may be useful for measuring the adequacy of bypass graft conduits.