Objective-Reactive hyperemia is the compensatory increase in blood flow that occurs after a period of tissue ischemia, and this response is blunted in patients with cardiovascular risk factors. Key Words: endothelium Ⅲ cardiovascular risk Ⅲ surrogate markers Ⅲ reactive hyperemia Ⅲ flow-mediated dilation R eactive hyperemia is a complex response that occurs after a period of tissue ischemia and primarily depends on local production of adenosine and other non-endothelium-dependent vasodilators that dilate tissue microvessels. 1 Studies in humans have shown that endothelium-derived nitric oxide also contributes to reactive hyperemia. 2,3 Peak brachial artery hyperemic flow velocity after 5-minute cuff occlusion of the arm relates inversely to traditional cardiovascular disease risk factors 4 and to markers of inflammation 5 in the Framingham Heart Study. Smaller scale mechanistic studies suggest that the nitric oxide-dependent component of reactive hyperemia may be particularly affected by risk factors. 3 The relation of reactive hyperemia to the incidence of cardiovascular disease events in atherosclerosis has not been previously studied.

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Purpose Symptomatic atherosclerotic disease of the popliteal artery presents challenges for endovascular therapy. We evaluated the technical success, complications and midterm outcomes of atherectomy and angioplasty involving the popliteal segment. Methods We conducted a retrospective review of outcomes of popliteal artery intervention using atherectomy or angioplasty performed between 2003 and 2008. Results A total of 56 patients (36% women, age 72.8±12.2 years, 77% critical limb ischemia) underwent popliteal atherectomy (n=18) or angioplasty (n=38). These patients had similar clinical characteristics, TASC/TASC II classification, mean lesion length, and run-off scores. We observed a trend toward higher rates of technical success defined as <30% residual stenosis after atherectomy compared to angioplasty (94% vs. 71%, p=0.08). While angioplasty was associated with a higher frequency of arterial dissection (23% vs. 0%, p=0.003), atherectomy was associated with a higher rate of thromboembolic events (22% vs 0%, p=0.01). Adjunctive stenting was used more frequently following angioplasty compared to atherectomy (45% vs. 6%, p=0.005). Thrombolysis was used to treat embolization in 4 patients in the atherectomy group. The improvement in the ankle-brachial index was similar between the two treatment groups. Primary patency of the popliteal artery at 3, 6, and 12 months was 94%, 88%, and 75% in the atherectomy group and 89%, 82%, and 73% in the angioplasty group (p=NS). There were no significant differences in limb salvage and freedom from reintervention at 1 year between the atherectomy and angioplasty groups. Conclusions Our experience with popliteal artery endovascular therapy indicates a distinct pattern of procedural complications with atherectomy compared to angioplasty but similar midterm patency, limb salvage and freedom from intervention.

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Background: Postoperative gastrointestinal leak and venous thromboembolism (VTE) are devastating complications of bariatric surgery. The performance of currently available predictive models for these complications remains wanting, while machine learning has shown promise to improve on traditional modeling approaches. The purpose of this study was to compare the ability of two machine learning strategies, artificial neural networks (ANNs) and gradient boosting machines (XGBs), to conventional models using logistic regression (LR) in predicting leak and VTE after bariatric surgery. Methods: ANN, XGB, and LR prediction models for leak and VTE among adults undergoing initial elective weight loss surgery were trained and validated using preoperative data from the 2015-2017 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database. Data was randomly split into training, validation, and testing populations. Model performance was measured by the area under the receiver-operating characteristic curve (AUC) on the testing data for each model. Results:The study cohort contained 436,807 patients. The incidences of leak and VTE were 0.70% and 0.46%. ANN (AUC 0.75, 95% CI, 0.73 -0.78) was the best-performing model for predicting leak, followed by XGB (AUC 0.70, 95% CI, 0.68 -0.72) and then LR (AUC 0.63, 95% CI, 0.61 -0.65, p < 0.001 for all comparisons). In detecting VTE, ANN, XGB, and LR achieved similar AUCs of 0.65 (95% CI, 0.63-0.68), 0.67 (95% CI, 0.64-0.70), and 0.64 (95% CI, 0.61-0.66) respectively; the performance difference between XGB and LR was statistically significant (p = 0.001).Conclusions: ANN and XGB outperformed traditional LR in predicting leak. These resultssuggest that ML has the potential to improve risk stratification for bariatric surgery, especially as techniques to extract more granular data from medical records improve. Further studies investigating the merits of machine learning to improve patient selection and risk management in bariatric surgery are warranted.

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The development of an objective, noninvasive method to assess the hemodynamic effects of venous surgery has long been awaited. Previous methods used to evaluate the results of surgery for varicose veins and venous stasis ulceration have been limited in their quantitative assessment. Now, by use of air plethysmography (APG), we can accurately quantify the effectiveness of corrective venous surgery. Twenty-five extremities that had evidence of venous insufficiency were examined with use of APG before and after venous surgical procedures. Surgery was directed at specific sites of venous incompetence as defined by physical examination and high-resolution duplex imaging. Twenty-one extremities underwent ligation and stripping of the greater saphenous vein. In these patients, APG showed an improvement in venous reflux as demonstrated by a decrease in the venous filling index from 6.6 +/- 0.7 ml/sec to 1.8 +/- 0.3 ml/sec (p = 0.0001) and venous volume from 177.1 +/- 14.5 ml to 139.2 +/- 8.9 ml (p = 0.0008). In addition, these patients showed a mild improvement in calf muscle pump function as noted by an improvement in ejection fraction from 45.8 +/- 2.0% to 50.8% +/- 2.5% (p = 0.07). The residual volume fraction decreased from 45.0% +/- 3.4% to 42.0% +/- 3.7%, a difference that was not statistically significant (p = 0.4). Four extremities with grade III chronic venous insufficiency underwent popliteal vein valve transplantation with use of an autogenous axillary vein valve.(ABSTRACT TRUNCATED AT 250 WORDS)

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