Accuracy and utility of three-dimensional contrast-enhanced magnetic resonance angiography in planning carotid stenting

BackgroundContrast-enhanced magnetic resonance angiography (CE-MRA) is a proven diagnostic tool for the evaluation of carotid stenosis; however, its utility in planning carotid artery stenting (CAS) has not been addressed. This study assessed the accuracy of three-dimensional CE-MRA as a noninvasive screening tool, compared with digital subtraction angiography (DSA), for evaluating carotid and arch morphology before CAS.MethodsIn a series of 96 CAS procedures during a 2-year period, CE-MRAs and DSAs with complete visualization from the aortic arch to the intracranial circulation were obtained before CAS in 60 patients. Four additional patients, initially considered potential candidates for CAS, were also evaluated with CE-MRA and DSA. The two-by-two table method, receiver operating characteristic curve, and Bland-Altman analyses were used to characterize the ability of CE-MRA to discriminate carotid and arch anatomy, suitability for CAS, and degree of carotid stenosis.ResultsThe sensitivity and specificity of CE-MRA were, respectively, 100% and 100% to determine CAS suitability, 87% and 100% to define aortic arch type, 93% and 100% to determine severe carotid tortuosity, and 75% and 98% to detect ulcerated plaques. CE-MRA had 87% sensitivity and 100% specificity for the detection of carotid stenosis ≥80%. The accuracy of CE MRA to determine optimal imaging angles and stent and embolic protection device sizes was >90%. The operative technique for CAS was altered because of the findings of preoperative CE-MRA in 22 procedures (38%). The most frequent change in the operative plan was the use of the telescoping technique in 11 cases (18%). CAS was aborted in four patients (5%) due to unfavorable anatomy identified on CE-MRA, including prohibitive internal carotid artery tortuosity (n = 1), long string sign of the internal carotid artery (n = 2), and concomitant intracranial disease (n = 1). Among patients considered suitable for CAS by CE-MRA, technical success was 100%, and the 30-day stroke/death rate was 1.6%.ConclusionsContrast-enhanced magnetic resonance angiography of the arch and carotid arteries is accurate in determining suitability for CAS and may alter the operative technique. Certain anatomic contraindications for CAS may be detected without DSA. Although CE-MRA is less accurate to estimate the degree of stenosis, it can accurately predict imaging angles, and stent and embolic protection device size, which may facilitate safe and expeditious CAS

Defining the type of surgeon volume that influences the outcomes for open abdominal aortic aneurysm repair

ObjectivePrior studies have reported improved clinical outcomes with higher surgeon volume, which is assumed to be a product of the surgeon's experience with the index operation. We hypothesized that composite surgeon volume is an important determinant of outcome. We tested this hypothesis by comparing the impact of operation-specific surgeon volume versus composite surgeon volume on surgical outcomes, using open abdominal aortic aneurysm (AAA) repair as the index operation.MethodsThe Nationwide Inpatient Sample was analyzed to identify patients undergoing open AAA repairs for 2000 to 2008. Surgeons were stratified into deciles based on annual volume of open AAA repairs (“operation-specific volume”) and overall volume of open vascular operations (“composite volume”). Composite volume was defined by the sum of several open vascular operations: carotid endarterectomy, aortobifemoral bypass, femoral-popliteal bypass, and femoral-tibial bypass. Multiple logistic regression analyses were used to examine the relationship between surgeon volume and in-hospital mortality for open AAA repair, adjusting for both patient and hospital characteristics.ResultsBetween 2000 and 2008, an estimated 111,533 (95% confidence interval [CI], 102,296-121,232) elective open AAA repairs were performed nationwide by 6,857 surgeons. The crude in-hospital mortality rate over the study period was 6.1% (95% CI, 5.6%-6.5%). The mean number of open AAA repairs performed annually was 2.4 operations per surgeon. The mean composite volume was 5.3 operations annually. As expected, in-hospital mortality for open AAA repair decreased with increasing volume of open AAA repairs performed by a surgeon. Mortality rates for the lowest and highest deciles of surgeon volume were 10.2% and 4.5%, respectively (P < .0001). A similar pattern was observed for composite surgeon volume, as the mortality rates for the lowest and highest deciles of composite volume were 9.8% and 4.8%, respectively (P < .0001). After adjusting for patient and hospital characteristics, increasing composite surgeon volume remained a significant predictor of lower in-hospital mortality for open AAA repair (odds ratio, 0.994; 95% CI, .992-.996; P < .0001), whereas increasing volume of AAA repairs per surgeon did not predict in-hospital deaths.ConclusionsThe current study suggests that composite surgeon volume—not operation-specific volume—is a key determinant of in-hospital mortality for open AAA repair. This finding needs to be considered for future credentialing of surgeons

Cancer and thrombosis: Managing the risks and approaches to thromboprophylaxis

Patients with cancer are at increased risk of venous thromboembolism (VTE) compared with patients without cancer. This results from both the prothrombotic effects of the cancer itself and iatrogenic factors, such as chemotherapy, radiotherapy, indwelling central venous devices and surgery, that further increase the risk of VTE. Although cancer-associated thrombosis remains an important cause of morbidity and mortality, it is often underdiagnosed and undertreated. However, evidence is accumulating to support the use of low-molecular-weight heparins (LMWHs) in the secondary prevention of VTE in patients with cancer. Not only have LMWHs been shown to be at least as effective as coumarin derivatives in this setting, but they have a lower incidence of complications, including bleeding, and are not associated with the practical problems of warfarin therapy. Furthermore, a growing number of studies indicate that LMWHs may improve survival among patients with cancer due to a possible antitumor effect. Current evidence suggests that LMWHs should increasingly be considered for the long-term management of VTE in patients with cancer

Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis

Background. Without strong evidence of benefit, the use of carotid endarterectomy for prophylaxis against stroke rose dramatically until the mid-1980s, then declined. Our investigation sought to determine whether carotid endarterectomy reduces the risk of stroke among patients with a recent adverse cerebrovascular event and ipsilateral carotid stenosis. Method. We conducted a randomized trial at 50 clinical centers throughout the United States and Canada, in patients in two predetermined strata based on the severity of carotid stenosis—30 to 69 percent and 70 to 99 percent. We report here the results in the 659 patients in the latter stratum, who had had a hemispheric or retinal transient ischemic attack or a nondisabling stroke within the 120 days before entry and had stenosis of 70 to 99 percent in the symptomatic carotid artery. All patients received optimal medical care, including antiplatelet therapy. Those assigned to surgical treatment underwent carotid endarterectomy performed by neurosurgeons or vascular surgeons. All patients were examined by neurologists 1, 3, 6, 9, and 12 months after entry and then every 4 months. End points were assessed by blinded, independent case review. No patient was lost to follow-up. Results. Life-table estimates of the cumulative risk of any ipsilateral stroke at two years were 26 percent in the 331 medical patients and 9 percent in the 328 surgical patients—an absolute risk reduction (±SE) of 17±3.5 percent (P\u3c0.001). For a major or fatal ipsilateral stroke, the corresponding estimates were 13.1 percent and 2.5 percent — an absolute risk reduction of 10.6±2.6 percent (P\u3c0.001 ). Conclusion. Carotid endarterectomy was still found to be beneficial when all strokes and deaths were included in the analysis (P\u3c0.001). Carotid endarterectomy is highly beneficial to patients with recent hemispheric and retinal transient ischemic attacks or nondisabling strokes and ipsilateral high-grade stenosis (70 to 99 percent) of the internal carotid artery. (N Engl J Med 1991; 325:445–53.). © 1991, Massachusetts Medical Society. All rights reserved

The relationship of the factor V Leiden mutation or the deletion-deletion polymorphism of the angiotensin converting enzyme to postoperative thromboembolic events following total joint arthroplasty

BACKGROUND: Although all patients undergoing total joint arthroplasty are subjected to similar risk factors that predispose to thromboembolism, only a subset of patients develop this complication. The objective of this study was to determine whether a specific genetic profile is associated with a higher risk of developing a postoperative thromboembolic complication. Specifically, we examined if the Factor V Leiden (FVL) mutation or the deletion polymorphism of the angiotensin-converting enzyme (ACE) gene increased a patient's risk for postoperative thromboembolic events. The FVL mutation has been associated with an increased risk of idiopathic thromboembolism and the deletion polymorphism of the ACE gene has been associated with increased vascular tone, attenuated fibrinolysis and increased platelet aggregation. METHODS: The presence of these genetic profiles was determined for 38 patients who had a postoperative symptomatic pulmonary embolus or proximal deep venous thrombosis and 241 control patients without thrombosis using molecular biological techniques. RESULTS: The Factor V Leiden mutation was present in none of the 38 experimental patients and in 3% or 8 of the 241 controls (p = 0.26). Similarly there was no difference detected in the distribution of polymorphisms for the ACE gene with the deletion-deletion genotype present in 36% or 13 of the 38 experimental patients and in 31% or 74 of the 241 controls (p = 0.32). CONCLUSIONS: Our results suggest that neither of these potentially hypercoaguable states are associated with an increased risk of symptomatic thromboembolic events following total hip or knee arthroplasty in patients receiving pharmacological thromboprophylaxis

Endothelial Linings in Prosthetic Vascular Grafts

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73894/1/j.1749-6632.1987.tb33036.x.pd

Polycomb recruitment attenuates retinoic acid-induced transcription of the bivalent NR2F1 gene

Polycomb proteins play key roles in mediating epigenetic modifications that occur during cell differentiation. The Polycomb repressive complex 2 (PRC2) mediates the tri-methylation of histone H3 lysine 27 (H3K27me3). In this study, we identify a distinguishing feature of two classes of PRC2 target genes, represented by the Nr2F1 (Coup-TF1) and the Hoxa5 gene, respectively. Both genes are transcriptionally activated by all-trans retinoic acid (RA) and display increased levels of the permissive H3K9/K14ac and tri-methylated histone H3 lysine 4 epigenetic marks in response to RA. However, while in response to RA the PRC2 and H3K27me3 marks are greatly decreased at the Hoxa5 promoter, these marks are initially increased at the Nr2F1 promoter. Functional depletion of the essential PRC2 protein Suz12 by short hairpin RNA (shRNA) technology enhanced the RA-associated transcription of Nr2F1, Nr2F2, Meis1, Sox9 and BMP2, but had no effect on the Hoxa5, Hoxa1, Cyp26a1, Cyp26b1 and RARβ2 transcript levels in wild-type embryonic stem cells. We propose that PRC2 recruitment attenuates the RA-associated transcriptional activation of a subset of genes. Such a mechanism would permit the fine-tuning of transcriptional networks during differentiation

Renaissance concept of impetus

The concept of impetus denoted the transmission of a power from the mover to the object moved. Many authors resorted to this concept to explain why a projectile keeps on moving when no longer in contact with its initial mover. But its application went further, as impetus was also appealed to in attempts to explain the acceleration of falling bodies or the motion of the heavens. It was widely applied in Renaissance natural philosophy, but it also raised a number of ontological questions concerning its precise nature