Saphenous vein harvesting techniques for coronary artery bypass grafting: a systematic review and meta-analysis.

The great saphenous vein (GSV) graft remains a frequently used conduit for coronary artery bypass graft (CABG) surgery. The optimal technique for GSV harvesting has been the subject of on-going controversy. We therefore sought to conduct a systematic review and meta-analysis of all available GSV harvesting techniques in CABG. A systematic search of 12 electronic databases was performed to identify all randomized controlled trials (RCTs) of any GSV harvesting technique, including conventional vein harvesting (CVH), no-touch, standard bridging technique (SBT) and endoscopic vein harvesting (EVH) techniques. We investigated safety and long-term efficacy outcomes. All outcomes were analyzed using the frequentist network meta-analysis. A total of 6480 patients from 34 RCTs were included. For safety outcomes, EVH reduced 91% and 77% risk of wound infection compared to no-touch and CVH, respectively. EVH and SBT also significantly reduced the risk of sensibility disorder and postoperative pain. The techniques were not significantly different regarding long-term efficacy outcomes, including mortality, myocardial infarction and graft patency. For GSV harvesting for CABG, EVH techniques are the most favorable, but in case of using an open technique, no-touch is more recommended than CVH. More effective and safer procedures should be investigated for GSV harvesting in CABG.

Glabridin Relaxes Vascular Smooth Muscles by Activating BKCa Channels and Inhibiting Phosphodiesterase in Human Saphenous Vein.

The aim of the current study was to investigate the pharmacological activity of glabridin on the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed during bypass surgery, and 4-mm lengths of the vessels were placed in Krebs solution at +4°C and hung in an isolated organ bath to assess their contraction/relaxation responses. The contraction/relaxation responses were recorded to observe if the cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) pathway mediates the relaxant effect of glabridin after treatment with blockers like ODQ (a guanylate cyclase inhibitor), KT5823 (a PKG inhibitor), isobutylmethylxanthine [IBMX, a phosphodiesterase (PDE) inhibitor], and cantharidin [Cant, a myosin light-chain phosphatase (MLCP) inhibitor]. Moreover, nitric oxide (NO), cGMP, and PKG levels in SV tissues were determined by ELISA after incubation with glabridin, N(ω)-nitro-L-arginine methyl ester (L-Name, a NO synthetase inhibitor), phenylephrine (PE), ODQ, IBMX, and KT5823. The results showed that glabridin relaxed the vascular smooth muscle of human SV pretreated with PE in a dose-dependent manner, which was independent of the endothelium. The vasorelaxant effect of glabridin was only inhibited by iberiotoxin (IbTX), Cant, and KT5823. Glabridin increased cGMP and PKG levels in SV homogenates, whereas it did not alter the NO level. The enhancing effects of cGMP and PKG levels by glabridin were abolished by ODQ and KT5823. In conclusion, glabridin has a vasorelaxant effect, which is associated with the activation of BKCa channels and inhibition of PDE.

What is the impact of preserving the endothelium on saphenous vein graft performance? Comments on the 'NO' touch harvesting technique.

Saphenous veins used for coronary artery bypass surgery are subjected to considerable vascular trauma when harvested by conventional methods. This vascular damage is responsible, at least in part, for the inferior patency of the saphenous vein when compared with the internal thoracic artery. The performance of saphenous vein grafts is improved when this conduit is harvested atraumatically using the no-touch technique. There is growing evidence that the success of the no-touch technique is due to the preservation of a number of vascular structures including the endothelium, vasa vasorum and perivascular fat. There is conflicting evidence regarding the degree of endothelial damage to the endothelium of conventional versus no-touch saphenous vein grafts. In general, it has been shown that this single layer of cells lining the lumen exhibits considerable damage associated with a combination of vascular trauma and high pressure intraluminal distension. Increased platelet aggregation and thrombus formation at the exposed subendothelial membrane is due to a local reduction of endothelium-derived factors including nitric oxide. In addition, damage to the vasa vasorum of conventionally-harvested veins will reduce transmural blood flow, a condition shown to promote neointimal hyperplasia and atheroma formation. By stripping off the perivascular fat during conventional harvesting, mechanical support of the graft is reduced and the source of adipocyte-derived factors potentially beneficial for graft patency removed. While most agree that endothelial damage to the saphenous vein affects graft patency, the contribution of other tissue-derived factors affected by vascular damage at harvesting need to be considered.

Evaluation of the Stress-Growth Hypothesis in Saphenous Vein Perfusion Culture.

The great saphenous vein (GSV) has served as a coronary artery bypass graft (CABG) conduit for over 50 years. Despite prevalent use, first-year failure rates remain high compared to arterial autograft options. Amongst other factors, vein graft failure can be attributed to material and mechanical mismatching that lead to apoptosis, inflammation, and intimal-medial hyperplasia. Through the implementation of the continuum mechanical-based theory of "stress-mediated growth and remodeling," we hypothesize that the mechanical properties of porcine GSV grafts can be favorably tuned for CABG applications prior to implantation using a prolonged but gradual transition from venous to arterial loading conditions in an inflammatory and thrombogenic deficient environment. To test this hypothesis, we used a hemodynamic-mimetic perfusion bioreactor to guide remodeling through stepwise incremental changes in pressure and flow over the course of 21-day cultures. Biaxial mechanical testing of vessels pre- and post-remodeling was performed, with results fit to structurally-motivated constitutive models using non-parametric bootstrapping. The theory of "small-on-large" was used to describe appropriate stiffness moduli, while histology and viability assays confirmed microstructural adaptations and vessel viability. Results suggest that stepwise transition from venous-to-arterial conditions results in a partial restoration of circumferential stretch and circumferential, but not axial, stress through vessel dilation and wall thickening in a primarily outward remodeling process. These remodeled tissues also exhibited decreased mechanical isotropy and circumferential, but not axial, stiffening. In contrast, only increases in axial stiffness were observed using culture under venous perfusion conditions and those tissues experienced moderate intimal resorption.

Evaluation of the effects of medial saphenous venous pressures as an indirect method of measurement of intra-abdominal pressures in the horse.

OBJECTIVE: To evaluate the effect of changes in intra-abdominal pressure (IAP) on medial saphenous venous pressure (MSVP) and hemodynamics in normal horses. DESIGN: Experimental, in-vivo study. SETTING: University Teaching Hospital. ANIMALS: Convenience sample of 7 mixed breed horses; 5 geldings, and 2 mares. INTERVENTIONS: Pneumoperitoneum was induced in horses under standing sedation with carbon dioxide gas using a laparoscopic insufflator for a total of 60 minutes to simulate clinical elevation in IAP. Pressure was increased stepwise to 20 mm Hg over 30 minutes, and maintained at that pressure for 30 minutes to evaluate the effect of sustained intra-abdominal hypertension. The MSVP and vital parameters were recorded, along with direct arterial blood pressure from the transverse facial artery. MEASUREMENTS AND MAIN RESULTS: As IAP increased, MSVP increased in a stepwise manner, in concert with changes in IAP. The consistency in measurement between MSVP and IAP was high (intraclass correlation coefficient = 0.92; P < 0.001) and repeated measures correlation was excellent (r = 0.98; P < 0.001). Heart rate was unchanged over the course of the experiment (P = 0.09), however, respiratory rate increased with increasing IAP (P < 0.001). Arterial blood pressure also increased with insufflation (P < 0.001), with a significant difference at an IAP of 15 mm Hg (P = 0.04). CONCLUSIONS: This report provides preliminary data demonstrating a strong correlation between equine MSVP and changes in IAP, similar to that observed in other species. Further investigations are needed to evaluate this relationship, and to confirm these results in clinical patients.

Mechanism of thromboxane receptor-induced vasoconstriction in human saphenous vein.

Saphenous vein (SV) is one of the most widely used graft material in patients undergoing coronary artery bypass graft surgery (CABG). Thromboxane A2 (TXA2) is implicated in graft failure by inducing vasoconstriction and platelet aggregation. The aim of this study is to investigate the mechanism involved in TXA2-induced vasoconstriction in human SV. The role of different inhibitors and blockers on U46619 (TXA2-mimetic)-induced vasoconstriction is investigated by using an isolated organ bath system. Relaxation responses to several mediators are evaluated in SV pre-contracted with U46619 and compared with those pre-contracted with phenylephrine. Our results demonstrate that U46619-induced contraction is completely blocked by myosin light chain kinase inhibitor ML-9 or TP receptor antagonist BAY u3405. Furthermore, U46619-induced contraction is partially inhibited by phospholipase C inhibitor U73122, protein kinase C inhibitor calphostin C, Rho-kinase inhibitor Y-27632, L-type calcium channel blocker nifedipine, store-operated channel inhibitor SKF96365 or removal of extracellular calcium. Relaxation responses to NO donor (sodium nitroprusside), guanylate cyclase (GC) stimulator (riociguat), phosphodiesterase (PDE) inhibitors (sildenafil, IBMX), adenylate cyclase (AC) activator (forskolin) and acetylcholine (ACh) are markedly reduced when U46619 is used as a pre-contraction agent. Our results demonstrate that influx of extracellular Ca2+ (through L-type calcium channels and store-operated calcium channels) and intracellular Ca2+ release together with Ca2+ sensitization (through Rho-kinase activation) are necessary components for TXA2-induced vasoconstriction in SV. Moreover, more pronounced decrease in vasorelaxation induced by several mediators (SNP, riociguat, sildenafil, IBMX, forskolin, and ACh) in the presence of U46619 when compared with phenylephrine suggests that there is a crosstalk between the TP receptor signaling pathway and PDE, AC, GC enzymes. We believe that the investigation of mechanism of the TXA2-induced vasoconstriction in SV will provide additional information for the prevention of SV graft failure.

The role of the adenosine triphosphate-sensitive potassium channels in pinacidil-induced vasodilatation of the human saphenous vein in patients with and without type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) increases cardiovascular complications. Diabetic vascular dysfunction is associated with the reduced activity of the different smooth muscle potassium (K+) channels. Thus, the objective of our study was to investigate the role of the adenosine triphosphate (ATP)-sensitive K+ (KATP) channels in the relaxant effect of potassium channel opener, pinacidil on the human saphenous vein (HSV) obtained from the patients with and without T2DM. The rings of HSV without the endothelium, obtained from the patients who had undergone coronary bypass surgery, were mounted in an organ bath system and isometric tension was recorded. The relaxation of HSV, precontracted with phenylephrine, was produced by pinacidil. The expression of KATP subunits (Kir6.1, Kir6.2 and SUR2B) was detected by immunohistochemistry and Western blot. Pinacidil produces comparable effects on HSV in patients with and without T2DM. The suppression of pinacidil effect and its maximal relaxation by glibenclamide, selective blocker of KATP channels, was more pronounced on HSV in patients without T2DM. All three types of KATP subunits are expressed on the smooth muscle cells of HSV. While there are no differences in the expression of Kir6.1 and Kir6.2, the expression of SUR2B is lower in HSV in patients with T2DM. Pinacidil produced comparable KATP-dependent and -independent relaxation of the HSV in patients with/without T2DM. According to the effect of glibenclamide and the applied molecular analysis, presented findings demonstrated that diabetes mellitus was associated with the reduced expression of SUR2B subunit in the vascular smooth muscle of HSV.

Minimally invasive multivessel coronary bypass surgery: Angiographic patency data.

OBJECTIVE: Minimally invasive multivessel coronary artery bypass grafting (MIM CABG) has demonstrated its safety, effectiveness and high rate of reproducibility. However, minithoracotomy CABG is still rarely performed. In this study, we retrospectively analyze the CT-angiographic graft patency rates for the patients subjected to this operation. METHODS: A total of 245 patients were subjected to MIM CABG by a left minithoracotomy approach between 2014 and 2018. The left internal thoracic artery (LITA) harvesting, proximal, and distal anastomoses were performed under direct vision. The patients then underwent 128-slice computed tomography coronary angiography (CTA). The angiographic results were obtained for 127 (51.8%) patients (the follow-up period of 31.1 ± 7.8 months, from 15 to 45 months). Of the total patients, 204 (83.2%) were followed clinically during the time period from 12 to 56 months. RESULTS: Complete revascularization was performed for all the patients. The mean number of grafts was 2.6 ± 0.5. The perioperative mortality was 0.4% (1 patient). There were two conversions to sternotomy (0.8%), four reopenings for bleeding (1.6%), three myocardial infarctions (1.2%), and one stroke (0.4%). Twenty-two patients (9.0%) received transfusions. The long-term mortality was 4.4% (nine patients). Three patients (1.5%) suffered from a stroke during the follow-up period. For five patients (2.4%), repeat revascularization was necessary. For the examined patients, the overall graft patency rate was 89.8%, the LITA graft patency rate was 98.4%, the radial artery patency was 100%, and the saphenous vein graft patency was 84.0%. CONCLUSIONS: MIM CABG allows complete surgical revascularization with excellent clinical outcomes and promising angiographic graft patency rates.

Measurement of ambulatory venous pressure and column interruption duration in normal volunteers.

BACKGROUND: Ambulatory venous pressure (AMVP) measurement is considered the gold standard in evaluating calf pump function in chronic venous disease. The AMVP protocol was standardized in the 1970s with pressure monitoring through the dorsal foot vein. This technique was based on the belief that it represents calf venous pressure dynamics owing to rapid equilibration in the superficial and deep systems. This notion is subject to some doubt not only on theoretical grounds, but also owing to a lack of clinical correlation in a segment of the population with chronic venous disease. Our aims were to (1) examine if AMVP measured simultaneously through the dorsal foot vein (DFV) and the great saphenous vein (GSV) would be similar and (2) attempt to devise a noninvasive substitute via duplex measurement for the AMVP test. METHODS: The study was conducted in 76 limbs in 38 normal volunteers. Simultaneous AMVP measurements in DFV and GSV were made in 28 of these normal limbs. Column interruption duration (CID) after calf pump ejection was measured by monitoring duplex resumption of flow in the tibial veins and GSV after calf ejection. The return of AMVP back to baseline implies column restoration. The venous refill time therefore represents the CID via the pressure method. The pressure and duplex methods of CID were compared in the GSV. RESULTS: Key AMVP parameters (percent drop and venous refill time) significantly differed in DFV and GSV, showing a lack of pressure equilibration. CID measured by duplex in GSV was not significantly different from pressure-derived CID in the same vein. CONCLUSIONS: AMVP measured through the DFV does not reflect calf pump generated pressure events in GSV. A duplex method of measuring CID in GSV and posterior tibial vein is described. Duplex-derived CID is not significantly different from pressure-derived CID in the GSV.

Effects of two isometheptene enantiomers in isolated human blood vessels and rat middle meningeal artery - potential antimigraine efficacy.

BACKGROUND: Racemic isometheptene [(RS)-isometheptene] is an antimigraine drug that due to its cardiovascular side-effects was separated into its enantiomers, (R)- and (S)-isometheptene. This study set out to characterize the contribution of each enantiomer to its vasoactive profile. Moreover, rat neurogenic dural vasodilatation was used to explore their antimigraine mechanism of action. METHODS: Human blood vessel segments (middle meningeal artery, proximal and distal coronary arteries, and saphenous vein) were mounted in organ baths and concentration response curves to isometheptene were constructed. Calcitonin gene-related peptide (CGRP)-induced neurogenic dural vasodilation was elicited in the presence of the enantiomers using a rat closed cranial window model. RESULTS: The isometheptene enantiomers did not induce any significant contraction in human blood vessels, except in the middle meningeal artery, when they were administered at the highest concentration (100 µM). Interestingly in rats, (S)-isometheptene induced more pronounced vasopressor responses than (R)-isometheptene. However, none of these compounds affected the CGRP-induced vasodilator responses. CONCLUSION: The isometheptene enantiomers displayed a relatively safe peripheral vascular profile, as they failed to constrict the human coronary artery. These compounds do not appear to modulate neurogenic dural CGRP release, therefore, their antimigraine site of action remains to be determined.

Changes in trunk veins of the lower limbs in women with premenstrual leg heaviness and swelling.

BACKGROUND: The aim of this study was to investigate vein changes during the menstrual cycle in parous women with premenstrual leg heaviness. METHODS: А total of 39 women with heavy legs before menstruation were examined. Great saphenous vein (GSV) in the groin, femoral vein (FV) and popliteal vein (PV) were examined with ultrasound scanning before 10 a.m. and after 6 p.m. on days 1 to 4 (menstrual phase) and 25 to 28 (secretory phase). To characterize biophysical features of veins we used: 1) interphase gradient of the diameter (IGd), i.e. the difference in vein diameters during the secretory and menstrual phases; 2) orthostatic gradient of the diameter (OGd), i.e. the difference in vein diameters measured in the evening and in the morning. RESULTS: Diameter changings for GSV, FV and PV were similar. GSV diameter increased from the morning during the menstrual phase to the evening during the secretory phase on average by 26.2%. OGd was 0.73 mm (95% CI: 0.59-0.87) during the menstrual phase and 0.62 mm (95% CI: 0.54-0.71) during the secretory phase. IGd was 0.73 mm (95% CI: 0.61-0.86) already in the morning. During the secretory phase 43.6% patients had the GSV reflux. During the whole menstrual cycle GSV diameter in the reflux zone increased on average by 40.6%. IGd of GSV in this zone reached 1.25 mm (95% CI: 1.02-1.48) in the morning and 1.30 mm (95% CI: 1.25-1.35) in the evening. CONCLUSIONS: Women with premenstrual leg heaviness have a minimal vein diameter in the morning during the secretory phase. The maximal diameter is revealed in the evening during the secretory phase. Clinically manifested expansion of veins, including GSV refluxes, is found during the secretory phase due to increased expansibility of veins. However, because of increased creeping ability one observes expansion of veins during the whole menstrual cycle in these women.

Factors related to the size of venous leg ulcers: A cross-sectional study.

Venous leg ulcers (VLUs) are an important health problem, and the size of ulcers often affects patient care, healing time, and quality of life. However, the risk factors associated with ulcer size have been rarely reported. The aim of this study was to establish the risk factors for the size of venous ulceration by analyzing the patient demographics and the results of duplex ultrasonography.This study was an in-patient population-based cross-sectional study conducted at a single center during the period from 2013 to 2017. Men and women aged >18 years, who consecutively presented to our hospital with VLU, were included. According to the size of the ulcer, patients were divided into two groups, those with ulcers≤2 cm and those with ulcers >2 cm. Demographic, anthropometric, and clinical data were collected. For the analysis, univariate and multivariate logistic regressions were used.A total of 232 patients with VLUs were admitted to our hospital from 2013 to 2017, including 117 patients (50.4%) with ulcer diameters ≤2 cm and 115 patients (49.6%) with ulcer diameters >2 cm. According to the results of the multivariate analysis, the ulcer duration (P = .001), the diameter of perforating veins (PVs) around the ulcers (P = .025), the reflux time of common femoral veins (CFVs) (P = .013), the reflux time of great saphenous veins (GSVs) (P = .021), and the reflux time of PVs around the ulcers (P = .001) were independent risk factors for VLUs.These findings provide evidence that the size of VLU was significantly related to the ulcer duration, the diameter of PV around the ulcers, the CFV reflux time, the GSV reflux time, and the PV reflux time.

Intraoperative flow profiles of arterial and venous bypass grafts to the left coronary territory.

OBJECTIVES: The different mechanical and vasodilatory properties of arteries and veins may influence their flow profiles when used for coronary artery bypass grafting (CABG). This may be of significance when assessing the cut-off values for adequate flow. However, conduit-related flow differences are less examined. METHODS: In a study of 268 patients, transit time flowmetry parameters of 336 arterial and 170 venous conduits all grafted to the left coronary territory were compared. With transit time flowmetry, the mean graft flow (MGF), pulsatility index, percentage of diastolic filling and percentage of backwards flow were measured. Conduit-related differences were further compared according to on- or off-pump CABG (ONCABG versus OPCABG) surgery. RESULTS: Overall MGF and pulsatility index were comparable between arterial and venous grafts, but in arterial grafts, MGF was higher during ONCABG than during OPCABG (49.1 ± 35.3 ml/min vs 38.8 ± 26.6 ml/min; P = 0.003). Percentage of diastolic filling was higher in arterial grafts than in venous grafts (overall 71.0 ± 7.9% vs 63.7 ± 11.1%; ONCABG 69.9 ± 7.1% vs 63.9 ± 10.4%; OPCABG 71.9 ± 8.3% vs 63.4 ± 12.2%; all P < 0.001). Furthermore, percentage of backwards flow was higher in arterial grafts than in venous grafts in the overall (2.3 ± 3.2% vs 1.7 ± 3.2%, P = 0.002) and in the ONCABG (2.3 ± 3.2% vs 1.3 ± 2.5%, P < 0.001) cohorts. In venous grafts, percentage of backwards flow was lower during ONCABG versus OPCABG (1.3 ± 2.5% vs 2.6 ± 3.9%, P = 0.016). CONCLUSIONS: No statistically significant difference was observed for MGF and pulsatility index between arterial and venous conduits. However, arterial grafts have significantly higher diastolic filling and backwards flow than venous grafts. Furthermore, arterial grafts have a significantly higher MGF in ONCABG versus OPCABG.

Posterior tibial perforators relationship with superficial nerves and veins: A cadaver study.

BACKGROUND: Most authors have evaluated the location of lower leg arterial perforators, but little is still known about the relationship between the arterial network and great saphenous vein (GSV) and saphenous nerve (SN). The aim of this study is to evaluate the relationship between the arterial network of the posterior tibial artery perforators, the cutaneous nerves, and the superficial venous system in the lower one third of the leg. METHODS: Eighteen lower limbs from cadavers were used for this study. The arterial and venous compartment were selectively injected with a mixture of barium sulfate and epoxy. The specimen were CT scanned and the superficial veins, nerves, and the arterial perforators were dissected. RESULTS: A large perforator of the posterior tibial artery was found at a mean distance of 6.23 cm ± 0.88, with a 95% CI: 5.79-6.67, from the medial malleolus. The average diameter was 0.9 mm ± 0.17, with a 95% CI: 0.81-0.99. In 67% the connection of the venae comitantes to the superficial venous system was established with the GSV, in the other cases, with Leonardo's vein. Both dissection and imaging studies showed perineural interperforator connections along the branches of SN in all the specimens examined. CONCLUSIONS: The distribution pattern of posterior tibial artery perforators followed the superficial nerves in this region. There is an interperforator anastomotic network along the SN. The various patterns of the venous drainage system, in relationship to the distribution of the branches of posterior tibial artery perforators, have been clarified.

The haemodynamic causes of skin changes in limbs with primary varicose veins.

OBJECTIVES: To investigate the haemodynamic causes of skin changes in limbs with primary varicose veins, which were assessed with air plethysmography. METHODS: Five hundred seventeen consecutive patients with axial reflux in the great saphenous vein (varicose vein group) and 248 normal subjects (normal group) were investigated. Varicose vein group patients were divided into two groups according to whether they did (C4-6) or did not (C2-3) have skin changes. Several parameters obtained using air plethysmography were compared among the normal group, C2-3 and C4-6 patients. RESULTS: Although there was no significant difference in the regurgitation index to quantify venous reflux in C2-3 and C4-6 patients, the maximum arterial inflow rate increased (normal group < C2-3 < C4-6), even in limbs with a small amount of venous reflux. CONCLUSIONS: This study suggests that it is not essential to increase the venous reflux rate in skin change development; rather, it is based on various pathophysiological conditions that increase the arterial inflow rate.

Noninvasive vascular occlusion with HIFU for venous insufficiency treatment: preclinical feasibility experience in rabbits.

Venous insufficiency is a common disease arising when veins of the lower limb become incompetent. A conventional surgical strategy consists in stripping the incompetent veins. However, this treatment option is invasive and carries complication risks. In the present study, we propose noninvasive high-intensity focused ultrasound (HIFU) to treat lower limbs venous insufficiency, in particular incompetent perforating veins (mean diameter between 2-6 mm). Sonication parameters were designed by numerical simulations using the k-Wave toolbox to ensure continuous coagulation of a vein with a diameter superior or equal to 2 mm. The selected ultrasound exposures were 4 s pulses in continuous wave mode. Two types of sonication were studied: (1) fixed pulses and (2) moving pulses at constant speed (0.75 mm s-1) across the vein. The potential of these exposures to thermally occlude veins were investigated in vivo on rabbit saphenous veins. The impact of vein compression during ultrasonic exposure was also investigated. Fifteen rabbits were used in these trials. A total of 27 saphenous veins (mean diameter 2.0 ± 0.6 mm) were sonicated with a transducer operated at 3 MHz. After a mean 15 d follow-up, rabbits were euthanized and venous samples were extracted and sent for histologic assessment. Only samples with the vein within the HIFU lesion were considered for analysis. Simulated thermal damage distribution demonstrated that fixed pulses and moving pulses respectively placed every 1.5 and 0.5 mm along the vein and delivered at an acoustic power of 85 W and for 4 s were able to induce continuous thermal damages along the vein segments. Experimentally, both treatment parameters (1) and (2) have proven effective to occlude veins with a success rate of 82%. Occlusion was always observed when compression was applied. Our results demonstrate that HIFU can durably and non-invasively occlude veins of diameters comparable to human veins.

Proximal first: a beneficial strategy for no-touch saphenous vein graft.

In the mid-1990s, a novel saphenous vein harvesting technique, in which the vein is harvested with its surrounding tissue without manual distention, was introduced. This no-touch technique provides an excellent long-term patency; however, graft twisting and kinking should be given attention. To fully bring out the benefit of the no-touch method while reducing the risk of twisting and kinking, we have modified the anastomosis strategy. Our simple modified strategy involved a proximal anastomosis prior to the distal anastomosis. This strategy was successfully used in 16 patients.

Three Year Patency and Recurrence Rates of Revision Using Distal Inflow with a Venous Interposition Graft for High Flow Brachial Artery Based Arteriovenous Fistula.

OBJECTIVES: Upper arm arteriovenous fistulas (AVF) occasionally develop high flow. Revision using distal inflow (RUDI) effectively reduces flow of high flow accesses (HFA) in the short-term and is also popularised for treatment of haemodialysis access induced distal ischaemia (HAIDI). The long-term efficacy is unknown. The study's aim was to report on 3 year RUDI patency and recurrence rates for HFA with and without HAIDI. MATERIAL AND METHODS: This was a retrospective cohort study of patients with a HFA with or without HAIDI undergoing RUDI using greater saphenous vein (GSV) interposition between March 2011 and October 2017 at three facilities. AVFs were termed HFA if flow volumes exceeded 2 L/min on two consecutive measurements using dilution techniques. HAIDI was diagnosed as recommended. Following RUDI, follow up was not different from standard care in AVF patients. Data on post-operative flows and re-interventions were extracted from electronic patient files. Loss to follow up was avoided. Rates of patency and HFA recurrence were analysed. RESULTS: During the observation period, 21 patients were studied (7 females, 54 years ± 3). Fourteen had uncomplicated HFA whereas seven had additional HAIDI. Immediately post-operatively, flows decreased threefold (3120 mL/min ± 171 vs. 1170 mL/min ± 87, p < .001). Overall 3 year primary patency was 48% ± 12 (HFA, 55% ± 15 vs. HAIDI/HFA, 29% ± 17, p = .042). Secondary patency was identical in both groups (overall, 84% ± 9). Interventions were percutaneous transluminal angioplasty (n = 12, 9 patients), thrombectomy (n = 7, 3 patients), and revision with new interposition grafts (n = 3). After 3 years, 51% ± 12 were free of high flow (HFA, 32% ± 13 vs. HAIDI/HFA, 100%, p = .018). High immediate post-operative access flow predicted recurrence (OR 1.004 [1.000-1.007], p = .044). Patients with recurrence were 12 years younger than those without (p = .055). CONCLUSION: RUDI with GSV interposition for HFA offers acceptable patency rates after 3 years although re-interventions are often required. High immediate post-operative flows and young age are associated with recurrent high flow.

The anatomy and physiology of the terminal thoracic duct and ostial valve in health and disease: potential implications for intervention.

The thoracic duct (TD) transports lymph drained from the body to the venous system in the neck via the lymphovenous junction. There has been increased interest in the TD lymph (including gut lymph) because of its putative role in the promotion of systemic inflammation and organ dysfunction during acute and critical illness. Minimally invasive TD cannulation has recently been described as a potential method to access TD lymph for investigation. However, marked anatomical variability exists in the terminal segment and the physiology regarding the ostial valve and terminal TD is poorly understood. A systematic review was conducted using three databases from 1909 until May 2017. Human and animal studies were included and data from surgical, radiological and cadaveric studies were retrieved. Sixty-three articles from the last 108 years were included in the analysis. The terminal TD exists as a single duct in its terminal course in 72% of cases and 13% have multiple terminations: double (8.5%), triple (1.8%) and quadruple (2.2%). The ostial valve functions to regulate flow in relation to the respiratory cycle. The patency of this valve found at the lymphovenous junction opening, is determined by venous wall tension. During inspiration, central venous pressure (CVP) falls and the valve cusps collapse to allow antegrade flow of lymph into the vein. During early expiration when CVP and venous wall tension rises, the ostial valve leaflets cover the opening of the lymphovenous junction preventing antegrade lymph flow. During chronic disease states associated with an elevated mean CVP (e.g. in heart failure or cirrhosis), there is a limitation of flow across the lymphovenous junction. Although lymph production is increased in both heart failure and cirrhosis, TD lymph outflow across the lymphovenous junction is unable to compensate for this increase. In conclusion the terminal TD shows marked anatomical variability and TD lymph flow is controlled at the ostial valve, which responds to changes in CVP. This information is relevant to techniques for cannulating the TD, with the aid of minimally invasive methods and high resolution ultrasonography, to enable longitudinal physiology and lymph composition studies in awake patients with both acute and chronic disease.

MicroRNA-21 drives the switch to a synthetic phenotype in human saphenous vein smooth muscle cells.

Cardiovascular disease is a leading cause of morbidity and mortality. Smooth muscle cells (SMC) comprising the vascular wall can switch phenotypes from contractile to synthetic, which can promote the development of aberrant remodelling and intimal hyperplasia (IH). MicroRNA-21 (miR-21) is a short, non-coding RNA that has been implicated in cardiovascular diseases including proliferative vascular disease and ischaemic heart disease. However, its involvement in the complex development of atherosclerosis has yet to be ascertained. Smooth muscle cells (SMC) were isolated from human saphenous veins (SV). miR-21 was over-expressed and the impact of this on morphology, proliferation, gene and protein expression related to synthetic SMC phenotypes monitored. Over-expression of miR-21 increased the spread cell area and proliferative capacity of SV-SMC and expression of MMP-1, whilst reducing RECK protein, indicating a switch to the synthetic phenotype. Furthermore, platelet-derived growth factor BB (PDGF-BB; a growth factor implicated in vasculoproliferative conditions) was able to induce miR-21 expression via the PI3K and ERK signalling pathways. This study has revealed a mechanism whereby PDGF-BB induces expression of miR-21 in SV-SMC, subsequently driving conversion to a synthetic SMC phenotype, propagating the development of IH. Thus, these signaling pathways may be attractive therapeutic targets to minimise progression of the disease. © 2018 IUBMB Life, 70(7):649-657, 2018.